I had a friend/mentor that raced through the 70-80's. He confirmed all of the things you state about quench. I built a 450 cubic inch Pontiac with 12:1 CR for the street, using his advice. dual plane, 750 cfm Holley, 72 cc Edelbrock heads, portmatched intake. It made about 580 lb/ft on 93 octane. 4400# Catalina ran a 12.76 at 108 mph. He taught me about suspension, too. He has since passed to cancer, but I will never forget the lessons. I found David Vizard teaching the same theories.
Great to hear you talk about quench. Being in Australia and being primarily a Cleveland builder back in the 80's and 90's, I almost always used the 302, small port, closed chamber heads. Cheap, and plentiful to get at the time. I'd run pistons up to 0.010 above the deck. The cylinder heads were always clean in the quench areas, and the pistons would erode the machining marks off the tops of the pistons across the life of the motor. I did this because I was trying to achieve exactly what you described. Being country based, information wasn't as readily accessible back then as is is today, so a lot of what I did was simply based on best guess, and break it engineering. But even though I haven't built a customer engine for over 20 years now, I still get people asking me to build for them. Thank you for sharing your knowledge. It confirms for me what I thought I was doing was right, but also tells me where I wasn't. Great stuff Ben. Regards Greg
Thanks for confirming what I have said many times over and you are testament to this technique of building a better engine and it does not take a rocket scientists but good technique will do it everytime! This is the reason I tell people when they bring me the engine not to tear it down but have us together take it apart because it has a story to tell... You sir know your stuff as well and thanks again!
Invaluable knowledge, OGs like you and I walk aound with this stuff in our heads. We can hear if the combo Is right or wrong. You can't order this type of magic from Summit, And you can't fix a bad combo with a laptop and FuelTech. Keep it coming
Dave, you are correct and yes experience proceeds to wisdom and knowledge. Unfortunately some people have very hard heads and no matter how you explain things they just never listen! lol
Ben, I predict within the next two years your channel will be so much bigger than you can imagine. I have followed your racing career since your white ‘67 coupe in the late ‘80s lol. Best RU-vid wishes my friend, and thanks for sharing so much knowledge. #MustangTown #MuscleCarTimeMachine
Thanks Robert! I try to answer but there is so much going my way and I have to make time to respond. It is worth it from my side to engage my viewers in exchanging ideas and comments.
This video is very good, and true. Modern fuel doesn't burn the same as old fuel from the muscle car era. You can run high compression on pump gas with modern cylinder heads, you just have to get your A/F ratio right and then your timing. Old specs for A/F and timing apply to old tech. It's all in the tune. Make it proper.
BBC heads really suffer with their design... They're severely "undervalved" because of it and require some real trickery to get good numbers, from my experience. One thing I saw my friend do on a few different castings, was sink the exhaust valve (50 thou or more) so the incoming intake charge flows over top of the exhaust valve face (instead of finding it's way right out through the short side, where then it REALLY can't breathe) in the low lift/over lap phase. That was pretty much how my buddy, Nick, said it... I just tried to put it more simply... He ported heads for living, and always had some wild looking stuff over there. Anyways! Thanks a million for the wisdom, Ben!
Another great video from the best teacher anywhere!! I've built many race engines with 11 to 1 to 11.5 to 1 with closed chamber iron heads or open chamber milled. 36 degrees total on 91 pump gas. I always picked a cam profile with 106 lobe and a minimum of 230 degrees duration at .050. Overlap and Quench is your friend!
Hi Ben, one other aspect to consider that many don't when building their street engine is elevation. If a person lives in Denver (5,000 ft + elevation) and does the majority of his driving locally (like most do),he will be able to get away with a much higher static compression ratio than a person living in L.A. or San Diego (500 ft elevation). His engine will be much more responsive at 12.5-1 versus 9.5-1. And will run virtually zero risk of detonation because of the reduced atmospheric conditions. Keep the good info coming. 🍻
You are right about that elevation relationship with compression! Many miss this scenario and builds a 9.1 compression living at high altitude and wondering why his car is a dog! lol
Thank you sir for the recommendation appreciate it very much. I checked your channel as well and you gave a lot of thoughtful comments and sound advice to all from the novice to the true enthusiasts!
It's interesting to hear this all explained in this way. My mentor Clif Winters Kolostow who worked for Ed Miller Racing Enterprises back in the late 60's early 70's taught me how to build my little 340 Dodge to make a very mild package that made substantially more power than most factory big blocks. The foundation was a 340 block that was decked about .010", then we milled .060" off the cylinder head deck, presumably to bring the combustion chamber down to the 63.3cc factory spec, or so I thought, lol. I actually ended up with combustion chamber volumes in the 58-59cc range. We also used the .018" steel shim head gasket and the factory 1968-1970 10.5 to 1 flat top pistons with four valve reliefs. That little 340 was a monster that loved to eat big block cars. In 1979, when I built this engine, I did not know how to check the actual compression. The car ran fine with 37° total on 93 octane pump premium. It was in a 3300lb Dart Swinger with a 4 speed and 3.91 gears. I put about 30,000 miles on that 340 before I pulled it out. When I took the heads off I noticed that the top of the piston and the cylinder head were nearly clean in the area where they nearly contacted each other. In fact some areas were absolutely clean. You see by milling the heads .060" I had turned an open chamber head into a closed chamber head . The flat area of the combustion chamber was reduced to the point that the "high" points of the rough casting surface were milled off, indicating if I had gone another couple thousandths the rough casting would have been milled smooth. All these years later I did the math and discovered that way back when, I had been running over 13.2 to 1 compression in that little "Stock" looking 340! It never rattled even with that much total timing. I did a little more math and conservatively, that 340 was easily making 1 horsepower per cubic inch. There were quite a few other "Little" tricks done to it, but the real key was that "Quench" area that I didn't realize I had created with that much milling. I never even heard of quench area at that time. So this video reveals a lot to me. Thank you for uploading this!
Exact same thing happened with my first engine rebuild when I had pistons from a Honda engine swapped into Suzuki for higher comp but unexpectedly came out to be 0.6mm out of deck / overdeck , compressed gasket thickness being 1mm. The pistons came out to be taller than mentioned on spec sheet and made 13:1 instead of 11:1. At that time I had to make a call whether to mill the pistons on deck or let them be as is . I took the leap of faith thinking as long as I keep the revs under 6.5k rpm , the rod stretch won’t exceed 0.4mm. And went ahead with the 0.6mm overdeck pistons with a functional quench of 0.4mm . The engine ran of 97 Ron without any knock on stock ecu map which was meant for stock 9:1cr spec motor. With loads of torque and 25% improvement in fuel efficiency.
In cold weather conditions that 13:1 motor would even run on 91 ron pump gas for daily use and out of station trips, all on stock ecu fuel and iginition map meant for 9:1 cr. This Suzuki engine was a 1.6L SOHC G16b , running taller Honda d16 pistons , making 290psi cranking compression on STOCK CAM, but ported head.
Thank you Ben! I just had a 363 SBF built and was worried because my engine builder insisted that 11:1 CR was just fine for 93 octane on the street. (Sniper Stealth EFI on an Edelbrock RPM Airgap) The engine is going into my '85 Foxbody with a Magnum 6 speed. The Mahle flat top pistons sat .002 in the hole with a .041 MLS head gasket = .043 quench with AFR 195 Renegade heads. I feel so much better now about running 11:1 CR on pump gas!
Thank you sir and it seems like you got it right on this build and more power to you! The quench is good but you can gain more it you kept it a little bit more tighter and it will respond big time!
U better be running a cam in the mid 240's or more if you're planning on 11:1. Maximum compression is totally based off duration and overlap.... nothing else, except maybe a high octane fuel like e85.😅
Salamat and thanks for your support on my channel! I just wish I can break in the social media there in motorcycles and cars! Many know me here but not there!
ive been reading your articles on facebook. and im applying it on small engine.. and now on youtube w/ all the illustrations it is really much easier to understand. it realy helped me a lot.. thank you sir
Great info! I built a supercharged 377 Chevy. 9.23:1 on pump gas. Not huge cubic inch. But keeping quench tight. 400 block 4.155 bore 3.48 stroke. .035 quench with a semi flat/dished piston to get the 9.23CR. Cometic mls gaskets Everything I read says 7.5-8 to 1 with a weiand blower. Granted I have only ran about 6.5psi but so far so good.
Very interesting and quite good timing. They engine builder who Does my valve job suggested I should go with atleast 11:1 on my 3.4 v6 build for my Fiero. After seeing this I might just have to follow his advice, and yours to buy other pistons to replace the bowled ones I bought 😅
Tolerance to detonation is increased as well when you install a somewhat hotter street cam from stock so that will give you a little bit more power and response! Gas mileage too.
You just know when you are listening too a pro. Nothing to rehearsed if at all, all the numbers straight of the top of his head and they always run out of time. Mate you could have talked for an hour and I would have listened to every word. Just stumbled across this just now and subbed!
Sir I appreciate your videos . I glad I ran onto your web sight . I alway was told 200 ccp on a street engine. I run a bit more on my Harley but you have to be careful on not heat soaking or lugging . At any rate I was told a long time ago I could run a half point more compression with aluminum heads . I don't remember what I was told but way back when the aluminum heads they poured something through them to help with the heat loss .. most will say no way but I ran 12.5 in a 302 chev engine I built in I think 80 and I ran a 600 isky roller sold..that a a decent set of cast iron angle plug heads off a g gas car .. seems like I ran super unleaded and regular gas mix . I kept the engine at 160 also . I never as far as I know had problems . The engine had a 0 deck . I had help building the engine from a dirt track shop in Dallas and a fellow from my home town..since I found your channel I tried to watch all of them a great teaching opportunity. Thanks again
Thanks Jim. I feel 160* is too cold and you will have premature cylinder bore wear. If you can move that higher to 180*f the engine should run better and longer. Cast iron heads are not a laughing matter as you found out and at 12:5 it is at an advantage and you probably know that and I am not telling you anything you do not already know. Obtw thanks for supporting my channel.
Great video Mr. Alameda-love this topic! Your comment on CR vs load (vehicle weight) was thought provoking. I understand an engine works harder under load, however, I can't visualize how the combustion process is affected by load. What's got me stumped is, if an engine runs fine (no detonation) under light load, why would it change with load. Cylinder filling is what it is-at any giving RPM, at wide open throttle, and should not change based on load. What causes detonation-Is it CR, or is it the total psi within the cylinder? What say you? I'm in agreement with you on maximizing squish/quench to create turbulence/mixture motion within a cylinder. However, many moons ago, I believe it was a Circle Track article, where the engine builder had an opposing point of view. The engine builder's theory was to slow the motion in the chamber prior to ignition, to avoid extinguishing the flame front-was this the early stages of chamber softening? Thank you, Tony
Ts, what you will find and realize is the load vs. non load conditions within the combustion chambers! Under free revving the engine does not meet rpm resistance or slowing down of the rpms. When under load the rpm rise is stunted/delayed significantly while the FLAME FRONT SPEED DOES NOT SLOW DOWN. This situation of slower piston speed towards and after TDC will affect the "unburned" sections of the combustion chambers! Mainly around the intake valve relief @ the piston closest to the cylinder wall. ON THIS AREA IT SEE'S A RAPID RISE IN TEMPERATURES AND PRESSURES elevated to a point that auto- ignition emanates from this area. A secondary auto ignition is also present at the exhaust valve relief at the piston closest to the cylinder wall as well. Lean conditions at the intake valve pocket is exacerbated by the slower piston speed and the expansion of the ignited gases is still progressing at the same rate! Here the dangerous situation rears its ugly head and continues on towards pre-ignition! Like wise, the RICH CONDITIONS @ THE EXHAUST RELIEF results in a slower than normal ignition flame speed at this area because the richer mixture progression is slower BUT DOES NOT EXEMPT THIS AREA FROM THE SAME PRESSURE AND TEMPERATURE SPIKES SIMILAR TO THE INTAKE SIDE! Therefore a loaded engine's RPM RISE IS SLOWER. AN UNLOADED ENGINE RPMS IS FASTER! BOTH PRESENTS TWO DIFFERENT SCENARIOS AS PISTON SPEEDS SLOWS WHILE THE IGNITION FLAME SPEED STAYS THE SAME. Remember: Lean areas burn "slower" because the fuel molecules are farther apart. Rich areas also burn slower/cooler because rich mixtures are lazy and burns at a lower rate! In short if loaded or unloaded does not make a difference on chamber performance and conditions? Then why do we dyno an engine and tune ignition and air fuel ratios under load??? If load is unconsequential then we will just free rev the engine and set our tuning tables! But that would not work anywhere. The scenario above points to increase probability of detonation first from the intake side then the exhaust side if the conditions get progressively worse. The same loading conditions exist in 1st gear and the probability of detonation gets progressively worse the more you get to 2nd, 3rd and final 4th gear! The difference here is the slower rpm rise as you go thru the gears because the engine sees ever increasing "load" as you lose gear reduction thereby making the rpm rise much slower and here is where the problem starts! Big difference. I hope it is clear with you and thanks because it is an excellent and worthwhile question to answer. Lastly, an engine with no load does not build "boost" and the only way you can achieve it is to hold reverse and low gear/some 2nd gear on a transbrake! This will excite the combustion pressure to a higher level and the turbo will get a blast of exhaust pressures absent from a no load/light load situation. Proof that the combustion conditions are indeed different between load (added-weight) and no load/light load. Ben.
My builder is currently working on my original 69 corvette 427 390hp .070 over with 4.25 stroker kit making it a 498 ci. Flat top pistons are .020 down and plan to use .040 mls head gasket making quench .060. Due to matching numbers block we cannot mill for a zero deck to tighten quench. Builder doing 9.75 compression due to using factory BB iron heads and modern 93 pump gas. Factory heads have been ported 2.19 1.72 valves, titanium retainers. Comp solid roller cam 11-770-8 .639 .646 lift, 236 242 duration, 110 LSA. Tremec TKX 5-speed with 3:55 rear. Corvette will only see the street. I wanted a high torque street motor but wanted as much out of it as possible and look totally stock on the outside. Using original Rochester, intake and exhaust manifolds. Engine will be dyno’d before being put back in the Vette. Not sure under the circumstances what more could be done or changed? Thanks for your video!!
Could you tighten up the quench a little bit more? I feel everything looks good and would like it a little closer even -010 would work. Perhaps a cometic thinner gasket would work.
@@benalamedaracing2765Using a compression calc and a .040 MLS head gasket final compression will be 9.7522 to 1. Today I tried asking for a thinner gasket but he doesn’t want to increase compression with todays 93 gas using my original iron 290 heads. The heads have 99 cc’s 🤷🏻♂️
Get a mls .030 like Ben just explained, it’s not going to put you over 11.5:1 and the gains will be more than worth it. I run .027 mls gaskets with pistons.005 in the hole with no problems. Iron headed bbc. You could drop down to a .015 and still be at .035 quench and plenty safe. I too dealt with a machine shop that said 9:5.1 max for 93octane and iron heads.. Some shops just don’t understand quench. Going tight is key but .032 is as tight as I’ve gone myself.
@@phildo39645thanks for your reply. I was never able to convince builder to tighten up the quench. He kept saying if I used a .030 mls compression would be 9.9:1 and I’d ping with iron heads and today’s gas. The engine dyno’d 540hp 628tq using factory aluminum intake and Rochester carb.
I run 12 to 1 in my 6.4 hemi 2500 ram with a stock cam. I run tight quench, milled heads srt8 pistons, zero deck block... no knocking showing on the knock sensors. You can get away with it in a heavy vehicle also and it really helps mpg but I bet my NOX is pretty high...
Many years past Diamond Pistons provided a video on pouring their mold material into a combustion chamber which they would then use to build your pistons.. this was done on an engine stand with head mounted, mold goop then poured in from bottom of cylinder
It makes sense doesn't it whenever I go inside an empty room the sound travels and bounces on the walls like an echo chamber! Or perhaps an open chamber.
I have a good way to extract power from the dish piston no quench motors, with a cam and intake, use a Edelbrock Performer or an old SP-2P intake, not an RPM or anything, it has to have the tall narrow opening at the exit into the head. Then use a 108 LSA moderate lift cam, the scavenging of the cam and the high velocity of the intake creates a swirl/turbulence in the chamber of epic proportions, the engine acts like a 2 stroke at high RPM almost. This is for the guys who don't want to pull the motor and change pistons.
Jeff, sounds like it might work? Usually when you have high velocity ports combined with swirl/tumble, there is a big possibility you will centrifuge your fuel and separate from the airflow. There is an ideal port air speed street or racing and this is what we have to achieve in order for everything to work together and combust properly. Even high ram velocity into the chambers will lead to lean conditions like I explained on the piston intake valve relief breaking off or melting...
Rarely do i hear builders recommend any more than 11-11.5:1 compression for pump gas... I built my 438W 14 years ago with 12.42:1 comp. and 218# cyl. press. w/ 240 Hi-Ports, Zero detonation, 93 octane (ethanol free) with 30° total timing, idles at 850 rpm, makes an honest 740 horse at 6900rpm and 618 ft lbs tq. single carb, budget pump gas build, daily driver runs 190° in FL summer heat. The cam timing is critical with this amount of compression and a custom Comp. cam to my specifications, built in advance... provides its streetability. 3270# C4 5200 stall street car all motor 9.52 @141.80
You got it big time and that is moving no doubt! People and many of them do not realized the 351W configuration is plenty stout and even the factory block is light compared to other blocks with big mains.
Ben, I just found your videos haaa at 73 I have tried to tell people the same thing as you since the 60’s and they just didn’t get it. So I just stopped my life being too short. So glad your still trying nice job good luck! M
Had a 351 flat-top pistons with 289 HP heads (46 cc chambers) in a 67 Cougar, Nash 5-spd and 3.4 gears. Effectively 12.5:1 compression. No knocks on premium pump gas
This makes sense. years ago I had a decked 283 with flat tops, closed camber camel hump heads, and a cam in a 3500# car. It ran great on 87 octane. Pretty quick, high 12 second car, good power, never detonated. I now daily a 4800# square body suburban, with a stock, low compression, open chamber 882 smog headed 350. Its a turd, and it detonates on 87..
Another thing to add, try to get forged pistons made from 2618 alloy, and not 4032. 4032 alloy may fragment from the effects of detonation and if this happens, it can be very destructive of the engine. The forged 2618 alloy piston is much more resistant to the effects of detonation and heat.
Also, as a form of 'insurance'... although we have 93 octane here in Texas, I am lucky enough to have stations nearby that sell E85. I usually get a few Jerry cans full of E85 and add a couple of gallons to my tank before topping it off w/ 93 octane. E85 is 108 octane... and it also cools the burn of the fuel. With just a couple of gallons, you don't need to retune anything or get E85-specific equipment. Definitely see a difference, especially during these 105+ degree Texas summers.
I've got a 1971 383 with 906 heads and got about 9-1ratio. The cam is a factory Chrysler cheater cam which has a little over 300 duration I believe but stock lift of .450. since I have zero deck height pistons, I'm going to run a set of 1966 383 closed chamber heads. -9.5cc compared to the open chambers. .020 head gasket. I think closed chamber with flat top pistons pings less than open a chamber with a raised dome on the same octane of fuel. Chrysler called those heads "fast burn" and that's why they are expelling a lot of unburdened hydrocarbons. For a clean burn exhaust you can't go much above 8.5 compression. Open chamber heads are nothing but smog heads for their slower burn. No quenching here and no performance, but cleaner and less hydrocarbons for the catalytic converter to reburn.
Excellent content!! It sometimes becomes difficult to run a flat top with a large 500+ ci stroker, because if you do you'll have like 15:1 compression!
I think you have it backwards. With a bigger bore, such as in a 540 BBC, you need less of a dome to achieve the same compression. With a 454, you need a bigger dome to get a good compression ratio.
@@ekitchingany time you increase the cylinder volume you increase the CR if the closed volume stay the same. 540 has 1/4 more bore and 1/4” more stroke than a 454 also.
Very good video and reaches most of the street audience like you said. Like your perspective on compression ratio too - tske all thats there for pump gas. On point wotg tq vs RPM too. Subscribed. I have a 430W just built and dyno'd on my channel. Definitely a fan of the 8.2/9.5 deck Windsors.
i prefer the Windsor 9.5" deck over a chevy 350 deck, but its still not enough. i need 10 or 11 inch deck hieght at least with a 4" bore, even more with a 4.185" bore. That is why i am build my ford and chevy small block head using engines with custom DIY engine block with molecular iron. One day i hope to build a nano-molecular auto orbital quantum particle arranger and 'multi-D print' the son a bitch the way its supposed to be done. Then form for myself and others brand new bodies to live in for that matter.
I truly enjoy your theory application/ explanation videos. Guess it's my engineering mindset. Everyone loves horsepower, but don't understand the science involved. How does reverse dome pistons for boosted applications react? How do you increase/control combustion efficiency?
F&F, excellent question and makes me think this is why I love being asked about these scenarios! Reverse dome pistons for boosted applications is not a net negative and I will explain why. 1. Boost as part of the intake function in itself creates its own mixing by the mere presence of dense atmospheres inside the port! Boost does not happen if there are no rpms in the scenario given and with rpms comes the rapid stop n go of the charge column making it a very effective mixture motion assisting! 2. Boost comes with heat. Heat tends to excite the molecules and keep them from sticking to the port walls! These is the reason we have heated intake manifolds to keep the fuel from sticking to the cold port or manifold walls! A reason for the choke on ancient carburetors and the close loop function in modern EFI's. Purpose is to richen the mixture to compensate for fuel wetting and lean conditions inside the combustion chambers when it is cold! 3. Therefore with boost creating heat making the fuel particles more engage and active in the mixing process, and rpms obvious shaking and mixing prowess, the combustion chamber/reverse dome negatives are negated to a lesser role and we have a net horsepower increase!
@@benalamedaracing2765 Thank you for the lesson. Now it makes sense as to why at throttle response at idle (w/ reverse dome pistons) will not be as crisp as a NA motor. Of course important off the line. That's an interesting point in regards to heat and its' relation to making horsepower. Knowing the thermal efficient crossover point when heat is maximized for horsepower, versus causing detonations from heat of excessive compressed air (boost). I'm truly enjoy this! Thank you for broadcasting in a video platform. It's a bit easier for me to digest (understand) versus reading lol. Happy Holidays my friend!
Dead stock LS2 are 10.9:1 Suprized people haven't noticed. With modern heads and efi its so easy, especially when a big cam profile is added even 12:1 isnt too hard.
One thing with the LS is they come with good compression and great cylinder heads (fr. the factory) not too big and not small for the streets and high performance.
Good video Ben! I never really understood how piston shape affects the quench, you described it very well. I learned years ago from Tom Nelson of Nelson Racing Engines, to zero deck the block and use the head gasket to adjust the quench. Of course with a stock type steel head gasket this wouldn't work, you would have to put the piston further down in the hole.
With most engine if you are zero deck a .045 head gasket thickness or even tighter would work really good on a small block. What kind of engine do you have?
I had a smogger 454 with 8.5 to 1 compression. Oval port heads with a rectangular port intake and a mild cam. It did mid 13's and would probably have run on hobo piss. I don't trust the consistency of gas stations, keep the compression reasonable and you will have a more enjoyable ride, and a heavier wallet.
@@benalamedaracing2765 Nope. We had the intake and threw it on to see what would happen. It was fun in town and actually got decent highway mileage. I have a theory that fuel puddled at the step at normal rpm's and got sucked in when there was enough air flow acting like an accelerator pump. It was the perfect street set up as far as I'm concerned.
BMW and Mercedes have engines 11.5:1 from the factory. For coyote gen 2 is 11:1 and gen 3 is 12:1. All will run 93 octane and reduce octane with decreased timing advance. Each pt of compression is about 4% torque increase across the curve. So its certainly worth being concerned with.
I was running 10.5:1 back in 1992 using IRON Ported Windsor jr heads, we polished the chambers and i ran 93 octane with a "normal" 5.0 stang base type timing. No ping problems, just power. With aluminum head I would have run 11.5:1 back then. What inspired me was David Vizard "How to build horsepower" book.
Great presentation. My 12.5/1 boss 302 after sitting all winter just blew two spark plugs out of the heads. Just the porcelain came out not the steel part.
This video and presentation is extremely informative and helpful.... Ive been chewing tums for indigestion caused by me worrying about the Ford 300 inline six im building on a budget. I knew at 8.0.1 compression it wasnt going to make anything resembling power....itd be a lazy pig. So im having the block bored .050 over to accept a 360FE piston so i can have a true flat top piston and get a higher compression height, and we are decking the block and milling the head. Havent found any real info on it other than "people used to do this back in the day" , but i was hoping for something close to 10.1, and the camshaft is a custom grind 206/212 @.050 447/460 lift with stock 1.6 ratio rocker arms. Stayed mild on the cam since this engine will be limited by its rotating assembly to under 5000rpm. But now im being warned about a high dynamic compression ratio thatd make it too high for pump gas in the 4400 pound van the engine is going in. Any thoughts?
Yes it seems the cam is way too small! You have a lot of weight you are moving and adding duration even in the 214-218 range should not do any damaged.
Your taking about static compression. The Dynamic Compression is what counts. Dynamic has to do with valve timing events. If they are running 93 octane your dynamic will/should not be beyond 8.5:1 compression.
I explained that in detail on Part II of this video. A more simple technique is the cranking pressure not exceeding 200# and advancing or retarding the camshaft will increase or lower this number so further running pump gas without detonation. All explained in it.
@@benalamedaracing2765 Oh! Okay. I paid not see that vid. My apologies. Yes, cranking pressure would be a solid indicator also as you mentioned. Do you explain the tolerances needed for proper quench? How do you calculate the stretch of the rods so the piston doesn’t make contact with the head?
a few years back I acquired a 1990 Suburban with a 350. It would not pull a 5% grade on the interstate without down shifting and losing 20mph. SO, I pulled the engine. The engine wasn't factory colors so I assumed it had received a long black at some point. Compressions were factory fresh so I decided to leave the bottom end stock. SBC aluminum heads raise dcompression to 10.5 to 1. I aded a cam that was just shy of an idle gallop. A high rise intake, headers and an Edlebrock 1400 series carb. It dyno=d at 400hp and 390ft/lbs and ran everywhere on 87 octane without detonation
This is only relevant for two valve heads where the intake charge creates a centrifuge spinning fuel outwards, but pretty much every engine for the last 30 years has been four valve which creates a tumble so a flat or dished piston is preferred. The most efficient pistons for a modern engine are flat or dished with a perimeter quench area.
I agree with your last statement but your introduction is really off base, "only?" and let me explain to you why. Check frames 55:20 of this video and it will explain "tumble" motion and how the fuel molecules has to almost travel a full 360* turn to return some fuel to the 4V's intake short side! I have worked from 1250rwhp turbo six street engines to Mercedes Benz 24hrs of Daytona & 12hrs of Sebring endurance engines (pls check my 2JZ build on FB Ben Alameda Racing) which I go thru the details of cylinder heads and block design. Almost ALL 4v's do not have a short side to influence some kind of radius entry to the short sides enabling fuel to go to this lean areas! Almost ALL depends on tumble motions that slams the fuel to the opposite side of the cylinder walls under the exhaust valves. Piston movement shoves most of these fuel droplets to the exhaust pads/valves and hardly anything that somersaulted inside and on top of the pistons ended up on the intake valve/pads! These are the reality of endurance engines and it gets worse on drag application which entails much higher boost levels shoving the fuel stream to the extreme end of the cylinders (opposite the intake valves). Anyway, the saving grace is 4V's predominant mostly "small bore configuration" wherein the flame front can easily spread to the intake area due to the "centrally" located spark plugs compared to domestic 2V's having bore sizes way past 4 inch diameters, spark plug located on 1 side and below or mostly below the combustion chambers. Remember small bore engines have less chances of detonation compared to its bigger bore counterparts wherein the flame front, farther away from its ignition source increasing chances of secondaries by a wide margin due to temp./press. spikes before it is consumed by the expanding flame front.
My street engine in my Sonoma was dynoed on 89 pump and features 47cc chambers and custom Ross piston's for 10.7 to 1 which i'll be running on 91 pump. 399ci. 1st gen stroker.
Yes they do specially under boost or with alcohol fuel or methanol/nitro combined. Having primarily tumble with not much swirl or none at all NA then it is at a disadvantaged!
Back in high school I built a 10.5:1 327 with aluminum L98 heads for my '69 Nova. Everybody told me 10:1 was the limit for pump gas and that I'd have to use additives or reduce total timing. Luckily one of my auto shop teachers knew better. Thanks to the small chamber aluminum heads and flat top pistons with a tight quench the car ran just fine on 90 octane pump gas. Years later I built an 11:1 331 stroker using the same basic principals and Holley Systemax heads for my notchback. Again it ran fine on pump gas, including lots of passes at Englishtown, only detonating if you lugged it on a hill in 5th gear(which 5.0's did with stock compression). Would I build either of those engines with an "RV" cam and stick them in a full sized car or truck? No. Would I possibly go higher today if I had a reliable source of good E85? Absolutely.
Glad you got it right years ago and got the benefit of good power with the right compression on the streets! Thanks for your comment and appreciate the feedback big time!
Same concepts in heavier vehicles as well... I live at 5k elevation, and was told by all sources to not go past 9.5:1, or I'll blow up my engine... RV cam and 11.1:1 was the best running towing (25k gvw) engine I ran to that point. Understanding tuning is where people get into trouble. Give the engine what IT wants, not what you think it should have.
I see a lot of people build a big Windsor with 9:1 compression and not even making 400 rwhp. I always ask them why they are building blower motor and they say the same thing pump gas.
Too true Ben.. with the BS low compression open chamber heads of the 1970;s , 400 CID engines with 8:1 compression could barely make 200 horsepower. Pathetic.. It was a plan to create the fuel crisis
Gen 3 Coyote ( 2018 up in Mustang) runs 12 to 1 stock with Hyper pistons, usually check 220+ psi cranking...just fine on pump gas...however they have nice active knock sensors they will even ADD timing not just pull it ( DI and Port injection blended )
Good video for sure. Surprised the Cobra engine builders didn't know that about pump gas. I had JBA out of California build me an engine to go vintage racing in the early 90's, 351w about the same cam lift. J302 heads 11.5 to 1 and raced it with nothing but 93 octane pump gas. Ran perfectly fine. 30 to 40 minute races and practices. Engine is still in the car. I forgot total timing but probably around 34 degrees max.
@@benalamedaracing2765 They were the only company at that time using the new J302 head. The real brains for the engine build was Doug Baker. I don't know what happened to him. I talked to him personally a few times. He was pretty sharp when it came to building engines and figuring out what the customer wanted. I still wanted to drive the car on the street so we ended up with a crane cam originally ground for a Cleveland motor. Had 400 ft lbs. of flat torque curve. and still achieve 425 hp at around 6500. 1.7 rockers to get .580 to .590 lift. Speed pro pop up pistons, to do exactly what you described in the video. Great motor with longevity in mind. With the technology in head design that engine would probably be close to 500hp now, changing nothing else but head. J302 only flowed stock right around 210 cfm intake side.
I realized this when I looked at supersport street bikes. They have over 12.5 to 1 compression ratios and run on 91 octane gas. Modern 200 HP 1000 cc bikes are over 13 to 1 compression and weigh around 450 pounds. Not much load under normal operation.
Light weight with good gearing helps the engine big time! But most of all, a smaller bore diameter isn't as prone to detonation as a big bore engine combination.
I built 454 with .030 8.5 almost zero deck flat tops and open chamber oval ports. Comp XE284 hydraulic. PRW sportsman roller rockers. Single plane. 800 quick fuel. Advanced cam degree. Makes 520 torque @3200 and 460hp@6000. 78 camaro gutted 10" 3000 stall-4.11 rear. 11.90@110
What about compression for 87 octane? Nobody ever talks about that. My current build is a sbc 385 with about 9.5 compression with D dish pistons with .040 quinch, aluminum afr budget heads that I smoothed chambers and ports. Lunati 219/227 with .549/.565 lift 35.5° intake close going in a 3600lb car. Intended to be a fun fair weather daily driver with highway gears and a wide ratio overdrive 4 speed. Hopefully it'll be replacing the 35yo 4.3 that can no longer maintain the speed limit in a couple months. Just waiting on the block to get back from the shop now.
outlaw. I totally hear you and agree on 87 octane. How many want to spend extra $ on premium pump gas for a daily driver. I can understand a street/strip car, but not a daily. I for one would like to see more content on max performance from 87 octane, i think it's more realistic for thee average car guy. I do believe you have a very healthy combination to replace the worn out 4.3L with, it will be a fun ride for sure, plus hopefully decent on fuel. I would personally go with a good dual plane intake and a vacuum 750 carb. It should have really good low / mid range torque with this whole combo. 87 octane compatible for sure. I would do a compression test to see where you're at for cylinder psi. I have run many on 87 with between 170-180 psi with out an issue, I believe and have seen/ discovered that once you push it over 200 psi you'll need at least 91 or more. This has been my clued in indicator on what octane an engine can tolerate with out detonation. Of course with all else being equal, good radiator, high cfm fan, low temp thermostat, etc. The cam you have will bleed off cylinder pressure at low rpm, which will help with 87. But if I were to give pinpointed advice I would put most of my focus first on ignition timing, a dialed in distributor makes a world of difference for any engines performance, take the time to learn about and perform any adjustments needed to find out what the engine likes for timing, it knows what it wants to perform at its peak, you just have to find its sweet spot, every engine is different, time spent here will be well rewarded. second, on the air fuel ratio, aka, set float level, proper size jets, squirter's, etc, third, max cooling/ heat reduction. Once you get timing and AFR tuned in, you will have a Fantabulous 87 octane burner, for sure. Kudo's to you, my friend, I'm actually a bit jealous 🤫. Nice Combo.. 👍
@@brianwenzel8791 Thank you sir, Usually the only people who comment about an 87 build just comment like 12 year olds to say the least. Considering the cam is ground 6° advanced I could stand to retard it a little if I need to bleed off a little more pressure. Ordered a re-manufactured quadrajet. Turns out when I took it out of the box it's an 800cfm version. Winner winner chicken dinner lol. Talking to a guy now for a tuning kit for it for my set up. Intake is an old spread bore edelbrock performer.. 3701 i think? Cant remember the number, do know it's the egr version and that has been plugged off and I notched the center devider like the rpm air gap I use to have. Carb is a non computer version and numbers on it say it's an 85 model. I wanted the later version for the adjustable part throttle. That will be a big help on fuel mileage. Haven't owned a quadrajet in 20+ years, can't wait to hear that sound again. Distributor is a computer controlled freebe out of a late 80's truck. For some reason customer wanted a new one even though it had less than 3k miles on it so I kept it. The msd 6AL-2 controller just came in the mail today for it. I have everything but the pushrods, plug wires and starter. But yea back to 87. It never made sense to me that every performance build has to be 93 or higher. Thats $1.30 a gallon difference where I'm at for the life of the engine for an extra 20hp. The vast majority of 93 builds leave more than that on the table by overlooking simple free hp tricks. There's always someone faster and I'll never put a roll cage in the car so mid 7's in the 1/8th would be about my speed limit anyways.
I'm currently building a early 70's 351W short block that's been bored .060 over to a 363 with Keith Black flat top pistons and AFR 185cc heads with 58cc chambers and a Howards Cam Big Daddy Rattler hydraulic flat tappet camshaft. Should come out to a static compress ratio of around 11.1 or 11.2 and be pump gas drivable since the car it's going in is a 1971 small bumper Ford Maverick (grabber style but not a true grabber RPO code body), as this car only weighs around 2400 pounds.
That thing should fly with a lightweight maverick and most of all they hook very good compared to any mustang! I feel you will best move to a bigger cylinder heads from AFR perhaps a 195-200cc heads. Perhaps go to a hydraulic roller as well for more added power and torque.
@@benalamedaracing2765 yeah I might go hydraulic roller in the future. It was just a little out of budget for me right now plus even finding cams has been difficult lately! I was on a waiting list with Comp Cams for over 3 months before I cancelled my order with them and found the Howard's Cam I ended up going with. The springs in these AFR 185's are borderline on the seat and open pressures for a flat tappet, but I'm hoping it'll be okay since I'm removing the inner springs during break-in and will be using good break-in oil. Also, with the smaller heads, I'm at about 5,000 foot elevation where I live, so we have considerably less oxygen in the air, so my thinking with the slightly smaller head choice was maybe it'll help keep port velocities up which might work a little better than higher flow but slower velocity here at 5,000 feet. Maybe not, I dunno, but I figured it's worth a shot.
My theory is most detonation happens below 3000 rpm, I run automatics with a 3000 or more rpm stall converter, a cam with a lot of overlap, "0" decked block and 12:1 compression. Never had a problem.
This may be a dumb question but I’ll ask anyway. Does raising the octane with octane booster help to prevent detonation? I am new here and glad I found you. Very informative.
@@benalamedaracing2765 well there's a difference when we do hundreds of engines and most people only do a couple of them. Just in ignition, there is at least 5 variables that I can think of that influence how much compression can be run. In the 80's , I fine tuned a 4V Cleveland with 11 to 1 nominal compression ratio to get 19 mpg. But probably couldn't do it today, because of the gas available. Which is another variable.
The mod motors used the same pistons and cylinder heads for the 4.6 and 5.4l. I'm guess bean counters were involved in that decision. As a consequence of that and their long stroke, 5.4 pistons are something like .140" below the deck. Does anyone have an idea of how to utilize quench with those limitations in a street application?
Wow they come from the manufacturer with that much compression? I thought the mustangs and corvettes were high and that is pale in comparison to 13.1! Wow.
