Predicting Engine HP . . . without a dyno 

... and without a face diaper!

the rate for that was better than the rate for the V :)

Yeah right !

@@Hitman-ds1ei Actually Steve Brule had some high compliments about how intelligent Steve Dulcich was when I was talking to him at a dyno test we did in February of this year.

What's up @Steve Dulcich

@ steve dulcich only thing you invented is NOTTA. You want to learn about MOPARs I suggest you talk to Forrest Pitcock, he was developing engines for Chrysler starting in 1955 and was at the ground floor of the Wedge and Hemi back in the 50's to mid 60s. He's in Woodbury Tennessee, contact him Dulcich, you need to learn some and bring David Freiburger with you. You 2 clowns are the Beavis and Butthead of engines.

@@MasterWitchDoctor There's a Mopar wizard in woodbury??? I need to talk to him

It’s just a benchmark. He’s saying if you’re making more than 1.25 felt/ci, then your engine is pretty efficient / powerful by today’s standards. He explains it at 5:00

You are correct. Again, it's jsut a starting number. Every engine will be different - but if you tst hundreds of 10:1 compression street engiens - (not competition engines that achieve far more lb-ft/ci) you will see that many street engien shover around this 1.25 number. It's just an estimate - and the goal would be to bring it higher andmake moreI've built street engiens that make 1.4 lb-ft/ci and others that make less than 1.20. This is no hard and fast rule - it's jsut aa starting point. But use lb-ft/ci as a way to evaluate good engines from poor ones! That's the point of this video that I did not make clear.

What are your cam specs? It takes decent about of work to get 500 hp out of a 396

David, There are multiple variables involved with all of this. Your heads are circa 1960's so the chamber is not as efficient and while the oval port heads are decent, they are not world class, so yes 1.25 lb-ft per cubic inch might be a bit high. Plus, details like are you using a Performer RPM intake or something a little better, header size, cam timing, and about a dozen other tings will affect this. Perhaps a 1.2 lb-ft per C.I. might be a better number - that would produce 480 lb-ft torque. Remember, these are flywheel power numbers. If you have a mild cam, then it may not peak at 6,000 rpm. I recently built a 540 with a mild hydraulic roller that peaked at barely 5,300 rpm. That makes huge difference when calculating the peak hp number. In yoru case, 480 x 0.90 =432 lb-ft at peak hp x 5500 = 452 hp. That would be a much closer number to what you might achieve. Again, these are estimates. Hope this helps.

Jeff and Muscle Bone, Thanks for the replies. I knew the heads were going to be the weakest link in this equation, even with the additional work done to them. Those mods were done in the late 70’s and I didn’t have many other options I could afford. I am seriously considering one of the new aluminum heads you talked about in the previous big block combo episode. And possibly a hydraulic roller cam as well. The cam I have now is a hydraulic flat tappet, .542 and .554 lift, 227 and 233 duration at .050. With a 106 center and 110 lobe separation. The intake is a Wieand stealth and the headers are 2” hookers.

@@davidpoland7862 Your combination sounds pretty good - the lift for the amount of duration is also good - I just finished a story for EngineLabs that should be out soon that outlines a new line of Low Shock Technology camshafts that promise a little more power with improved durability but it might be a year or more before Comp makes these available. There are custom lobes available now - you would have to spec a custom cam. That's not difficult and may be something to consider. But really, better heads will deliver far more performance for the effort required. A good AFR oval port woudl be really good - but be forewarned that they raise the exhaust port - as most cylinder head companies do for Rat motors - this will make your headers more difficult to fit.

@@jeffsmith2003 thanks again for the reply. Since the motor is fresh and the cam is new, I'm probably leaning towards heads as the main upgrade. I have looked in to the AFR's and did notice the raised exhaust ports. I'm thinking the Edlebrock heads may fit the bill best. If I recall they don't have raised exhaust ports and have a small chambers, (100 cc's)? Which is very close to the chambers on the iron chevy heads I'm running now. This puts the compression at about 10.25 which is where I wanted to be, and less than the 11.0 of the stock L-78 pistons. Also I did see reference to the low shock cams somewhere, that I think you mentioned. It may have been in a recent response to a question for On All Cylinders, not sure. But I will look for the story at EngineLabs.

Use 1.32

This is based on roughly 10:1 compression so if we increase the compression to 11:1, in theory that should be worth around 4 percent power. Working the math backwards, that would make it roughly 1.3 lb-ft of torque per cubic inch and 12:1 would be roughly 1.35 lb-ft per cubic inch. It's important to note that airflow makes a big difference in power as well so you could have the same compression ratio but with more airflow and the power would also improve. This is a very generic formula that makes a ton of assumptions - but despite that - it still seems to work especially for street engines.

@@jeffsmith2003 thanks, I feel optimistic hoping for 450, the formula suggests around 550. I couldn’t be that lucky 😅

It's a good starting point. With more compression and/or beter heads that number can go up - or down! But it's a good place to start.

If you ise this eqito get your power figure then you can use another equation to predict boosted power.

Say you have 10lbs boost devide 10 by 14.7 add 1 and multiply that by your power figure. 10devided by 14.7 is .680. Plus 1 is 1.680. If gou have a 350 hp engine multiply 350x1.68 = 588 hp. These are all just figures derived from equations based on assumptions but it will get you someplace to start. And they are fairly accurate if you make adjustments for compression and that sort of thing. This equation isn’t mine I seen it on a Richard Holdener video I think and I believe he used to be part of the west tech Dyno facility too. Hope this helps.

@@johnnyatkins9097 - Thank you for this revision to the formula. I calculated my 2.3L EcoBoost using the standard formula and came up with some anemic numbers compared to the "factory" numbers. Add to that most of the EcoBoost engines have the OAR system, (Octane Adjust Ratio), that according to some online sources MAY, (stress on MAY), net you approximately 10% more HP if you run 93 octane. That % may be high but this much I do know, I noticed more "pull" running 93 octane after a couple of tanks ran through it. Online sources, (there it is again, the power of the internet), indicate that the stock 2.3L EcoBoost produces about 17-18 PSI of boost. I always triangulate on such information to get a consensus based on multiple sources. FWIW, the formula revision you posted does put the HP approximately where it should be.

Roughly 10:1 compression

This would not apply to "stock" engines. This applies to good, high performance (re) built engines. I.e., typical "hot rod" parts: Good aluminum aftermarket cylinder heads, performance (especially roller & retro roller) cams, good aftermarket intake manifolds, good (big) well-tuned carburetors, and properly sized headers (read: not too small).

With this math and if I did it correctly. My stock 5.3 would be 382hp. It's rated at 325 from GM. I can kinda believe that 382 with the modifications l did during the rebuild. My tuner said it should be about 375ish hp. Very cool video. Thank u sir

No your much closer to 350

@@junkyardrats1084 car was sold a few months ago. But the compression was very low.

As mentioned in the video, this simplified HP estimator is just that - an estimate that assumes (there's that word again) several things like a really good camshaft that is likely a roller with more lift than a flat tappet. Plus as mentioned several other variables. I ran the numbers to get your 551 hp at 6,000 rpm. The Ford numbers of 450 lb-ft of torque and 375 hp is using a stock and very mild flat tappet cam with a stock intake and cast iron exhaust. If you put headers, a better intake, a nice hydraulic roller cam, and enough carburetor it would probably make 530 lb-ft of torque and somewhere around 550 hp. If you tested a bone stock 429 - it will probably make more than the factory numbers - the OE's often under-rated their engines in order to pass through car inssurance regulations back in the day. Plus, the Boss 429 was rated at 5,200 rpm peak hp - way short of what you plugged into it at 6,000 rpm - do the math - with 1.25 x 429 and then peak hp at 5,200 - it comes to 475 . So it should be obvious that rpmplays a big part in this estimate. We are working with 20 to 30 variables here and yet estimating power to come up with a single number as the result. These are just estimates - it's possible that the Boss 429 isn't capable of 1.25 lb-ft per cubic inch. But I think it probably is - again assuming everythign else. Also consider that this 1.25 lb-ft/ci is based on using modern combustion chambers - which is what establishes combustion efficiency. A Boss 429 chamber may not be that good. But then again - it might be capable of actuall more since its close to a hemi chamber.

Absolutely - if and only if you are really good at building a normally aspirated engine. I'm assuming that David is referring to a pump gas engine. It's a great goal to use as a goal. As an example, my Iron Maiden 6.0L multi-part engine project that ran in Car Craft magazine (RIP) ultimately made 501 lb-ft of torque. That's 1.37 lb-ft/ci with a 100,000-mile used shortblock and less compression than it could probably use. So assuming another 15 lb-ft from better compression and ring seal, that would be 1.41 lb-ft /ci. So yes, a 1.45 number is achieveable and I did mention that this 1.25 lb-ft/ci number was just a typical street engine standard. As street normally aspirated engine builders get better at their tradecraft, that number will continue to climb. Jon Kaase told me that he sees around 1.55:1 lb-ft/ci for engines that win or place very high at Engine Masters. If you look back at the winning engines from the last few years - they are right there - but these are not street engines. They are really closer to NHRA Competition Eliminator engines with rules applied to them. I thnk that 1.6 might be a number you'd see with a NASCAR engine - perhaps more. That's a gues since I don't have access to current NASCAR engine information.

@@jeffsmith2003 Thanks for the response. Remember you from back in the magazine days. Anyways, it might be good to kinda guide folks on how they can up their torque on their street cars. Just too much emphasis on Hp. Torque rules on the street. ("Torque wins races, horsepower sells cars." Carroll Shelby)

David Vizard is hack and a clown. I challenged him to beat my 419 horsepower NHRA Stock eliminator 305 (428 horsepower now) vs his NHRA Stock Eliminator 305 build and he declined my challenge.

It's an average ..good heads intake, headers, 9 to 1 compression say. Based upon thousands of engine dyno pulls

This would be flywheel horsepower

He said small block chevy. V8 v8 v8

@@hankclingingsmith8707 cylinders dont matter, engine build type is the only thing that matters, the FACTOR 1.25 must be changed DOWN for stock and UP for build $$$$$$