Flowing Promaxx Ls3 large bore, small bore, and 245cc cathedral port heads. Edit: When I said small bore I meant 3.898bore which is 5.7. It is not for the 5.3l. Also I know 4.8 and 5.3 are same bore. Sorry for the confusion.
Hey Eric, Tim here, i'm NOT an LS guy, but WOW, some serious flow, and i really enjoyed ur comparison explanation between the 3..........great vid, just super cool!!!.....TY sir, peace to you!!
@@mikegillam1000 They bump the valve seats with a stone, and check/hone the guides, they send out their CNC work... I am in the industry, I know who does, what, and who buys from who... ProMaxx buys BBC/ LS heads from the same company as FloTek, except on the BBC FloTek puts the 2.300 valve in standard, ProMaxx charges extra for it.
That small bore LS3 style head WITH a factory LS3 intake would be an absolute RIPPER in an average street car build. Good stuff, thanks for taking the time to flow them all Eric.
Kinda looks like they sent you some ringer's. Full Port job with a little sand blasting to hide it the guides fully profiled. Still looks to be a real nice head.
One more thing in the small bore LS3's favor vs the cathedral is that LS3 intakes are relatively cheap and work really well - to get comparable performance out of a cathedral port intake you need to step up to something like a FAST. If you're running a high ram or something it's a moot point but for those of us with hood clearance issues it's something to consider.
I’m really enjoying seeing your perspective of Promaxx change over the past couple of years. I remember when you said you were gonna be sick when the Maxx 200 SBC head did so much better than the Brodix IK it was based on
Thanx Eric, learned so much from you. Just to be clear I'm a BBC. Guy. If I didn't know better after listening to this I'd swear I was listening to a LS fanboy. LOL. Thanx for all you do, I know, I know your not a super man!!
What i like is that you can order them in a 59 or 63cc . And when i soften the chambers im not losing a lot of compression and having to put a huge dome in to get it to 12 -1
Kinda crazy, a small block with bigger intake runners than it’s big block brothers. Man I can’t wait to get me some Promaxx heads for my sbf! You sold me on them. I remember when they came out, they were so cheap. Lees money than a cast iron vortex head and flowed better. I was thinking about getting them on my old Chevy short wide back in the day, but ended up selling the truck.
I have a 6.0 408 ls build that I’m looking to put a kong2650 supercharger on top of…go with the 240 or 260 heads? And why? Ps love your content and thanks for the info!
Hey Eric , love your cool videos , thank you so much for taking the time and explaining all the cool tips and tricks about your experience with LS Heads , i am at the point where i am going to build a LS 6.2 , what do you think about Frankenstein Heads ? thanks
Should be impressive with something along the lines of the Holley High Ram…provided the runners don’t have too much cross section. Would be interesting to juggle rocker ratios, for lift / valve curtain area, while maintaining velocity for the throat diameter.
The Promaxx stuff has come a long way, and their nice for guy on a budget wanting power. I don't run Sb-LS stuff, I'm a conventional-style Sbc Bbc guy, but my buddy's son has an LS 6.0 f3-112 procharger, and we used the Brodix BR 1 13 13.5° 245cc 2.10 int 1.6 exh cathedral port heads on it, and I'm a big fan of them and the combo.
Check again. they offer gen 1 traditional sbc heads that flow massive numbers!! He tested the 215 pro maxx head on the dyno, it made more than the afr heads. And promaxx offers even bigger heads. Here is the test. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-JhVa1LbUo3A.htmlsi=QzaiIEUrky8Gpm-X
@@DavidB7474 I know what heads and video you're talking about. I'm not saying their bad stuff. I been watching Eric for at least a few yrs. He does good stuff, I know a couple guys who run his stuff. For some that Promaxx stuff may be considered a good head, but I'm not a fan of AFR or Promaxx. I stick with Brodix castings and Profiler castings. I like the family owned and 100% American made stuff.
@@jasonstormoen I’m kind of upset dart stopped making cast iron heads. Work still offers the big 230 cc sbc heads. Some old stock of darts are still out there. Sad. You think companies will make stuff forever, but it’s not the case. When you find a company that makes quality it’s really difficult to change brands. Some of us are willing to pay for quality and the name, so I understand.
@@DavidB7474 Yeah, It does suck when a company has a good run on something, and they up and stop it. My thing, I may pay a little more for say a Brodix casting with say PSI or PAC springs and Manley Severe Duty valves, but I feel the stuff last long like T&D and Jesel shaft rockers.. Dart has went down a lot, it seems. Back in 99 I had a set of worked over Dart 23° 220's 2.12 int 1.6 exh, but when I sold them curtis turned me to Brodix and I just never looked back. I remember when the theory was Aluminum heads are for racing and not street use. Now Aluminum heads and blocks were doing drag and drive stuff no issue.
That's awesome my class i wish they would allow LS in circle track but i think there is another wingless sprint car class that is more open on engine rule like no 2 barrol you can run fuel injection. But it would be cool to try out the small bore LS Cathedral on a 6.0 because the cubic inch rule is 360 plus 2 percent which is 367 and the 6.0 is 364. So if i do go ls i will definitely go with those heads if i have the money and have you port them. But now my current engine rule since there is multiple Wingless class mine being spec amd have to run a 2 barrol our rule only allow any iron head iron block engine. So basically we just run sbc but at the end of this season i will get in contact with you again and hopefully to finally send you some stuff sorry it's been taking way to long but just trying to come up with some money.
I mean Over the years a larger port flows more and can achieve more hp but we don't race top end on dirt or anything like that so. A runner sized to provide low end response was always like you pointed out peak hp is nothing peak torque early and throttle response means alot more. Completely agree eric
would love to try these on my lsa zl1 but im afraid of the 63cc chamber being too small. stock is 69cc the compression might to to high or the valves could hit.
Hey brother, what do you think about the stock intake hollow stem valves on the 821 heads. I bought a pair of low mileage bare used heads for $300. I'm not building a race engine. Burnouts and ice cream. Ls3/6L80 swap in a 03'Crown Vic Police Interceptor. A toy for my wife and myself. Just a cam. Maybe 400-450 wheel. Btr .660 double valve springs. I've heard they like to snap off the tulip and destroy the engine. I can't spe d alot of money but I don't want garbage either. I seen you taking about the hollow stems. It will see some red lining sometimes. I'm not trying to join Street Outlaws is what I'm saying lol.
Your recommendation is sounding great for my applications but I didn't quite hear the model in which you was referring to. You were pointing to cylinder head in the middle speaking very highly of it could you please tell me the model. I wanna put them on a 6 .0,(Lq9) Create motor with sloppy stage 2 Elgin cam and a fast intake.
I really like promaxx heads, I’ve used a couple different sets. They do really good work. My only complaint is they don’t put helicoils or anything in the bolt holes. You’re just threading into aluminum.
I always if permitted, (rules) run my lifts about .050 above max flow lift simply because the valve stays at or above max flow for a longer amount of time or crankshaft degrees.
@@ChrisMcCutcheon-wj2pp you’re trying to compare a 257-260cc intake port to 240cc intake port on an aftermarket head. A stock ls3 head (821) head flows 310 cfm @ .500 why would an Escalade motor have more cfm? Especially since it doesn’t make peak hp like a ls3 ? 425 vs 401 Ported 823 heads are good for big cubes but not in stock form. And an average lt1 (direct injection) head is about 300 cfm @ .600 They dont need to flow as much stock because they achieved more hp through higher compression but since its direct injection it’s not as dangerous as it used to be. Idk if you have done the research. But either way its interesting how these heads achieve better cfm with a smaller port. Its pretty cool. Im gonna throw them on my 383ci ls1 gto
Two options. One is sold exactly as they come from promaxx except I flow one cylinder. Option two costs more which is me checking out the heads and flowing one cylinder
In your opinion, are those small bore 240 or 245 heads too much cylinder head for a 313cu/5.1L ? (3.905" Bore x 3.268" Stroke) .... essentially taking an iron block out to LS1/6 overbore with a 4.8L Crankshaft. The build would be for a lightweight 5speed cruiser (single cab Colorado truck). Thinking roughly .650 lift & 225 Duration close LSA camshaft, 7000 RPM max.
I wonder, if you opened the small bore head to the 6 liter bore size and unshroud it more, what would happen . Eric will you measure the chamber and tell me how wide it is. You have convinced me. Depending on the price
@@WeingartnerRacing nice! I was trying to talk my brother into the promaxx small bore ls3 for his 408 but he went with the Texas speed brawler ls3 heads because they were like 300 bucks cheaper but I feel his combo would benefit from the smaller runners on the promaxx. 408 isn’t going to need all of that ported ls3 head
If you have cathedral port with a head this good why change to ls3 or rec port but if you do that’s a win to as that small bore parties 60-80 rear wheel could be done with these
@WeingartnerRacing thanks for the response. Ill keep that in mind in the future. Unfortunately, i took a dremel to it the other day. It was small but it was 1/16- 1/8" deep. I feathered it out with plans of brazing it or welding it. I was worried carbon would build up in it and melt a hole through it.
@@WeingartnerRacing would you like to see a set? I'm planning to remove mine for winter check soon.maybe do fresh up and evaluate if you have any interest.
Has anyone used the Promax heads with promax supplied valves, are they good quality?, do you think they would hold up to 600+ hp all motor engine, love the videos watch them all the time 👍
Think the ls3 heads are big wait until a lt1 head gets in your shop...they flow 320cfm and are 297cc. The ports are HUGE. Edit..they have the same head bolt pattern but flipped and splayed valves. I dont know if they work with a ls bore plate
How many times do we have to tell you? 4.8 uses 5.3 pistons!!!! There is no reason to use compression ratio to spool your turbo unless you run a class that is turbo limited. In classes with a 76mm limit, I've heard those guys run upwards of 15:1 compression ratios.. Obviously you want to run more than traditional boosted SBC compression but 10:1 or so would be fine..
How much $$$ are the cathedral heads that will fit a 4.030" bore 6.0L LY6 iron blocked 390ci? Is there a CNC program for them yet to port them? Or a link to the manufacturer?
