The Stovebolt Site Forums The Shop Area The HiPo Shop Patriot/Promaxx aluminum heads

I just can't leave well enough alone. I'm regretting getting the 260 hp crate engine from Jegs last year. I guess I've been looking at too many episodes of Street Outlaws, but I want more power. I came across the link below and using the same engine they bumped the power up considerably with heads and a cam swap.

http://www.hotrod.com/how-to/engine/...head-shootout/

I came across a set of the Patriot (now Promaxx) aluminum heads mentioned in the write up for $500. Although they scored very well in the article I'm finding mixed reviews other places. Anybody using them? I've been on the phone with the Jegs techs and with a Comp cam, heads and the hi- flo Edelbrock tpi setup I'm using they say I can have a major increase in hp.

I'm just naturally suspicious of anyone who wants to help me out by selling me something. Could his/her objectivity be just the tiniest bit suspect? After doing a considerable amount of dyno testing on high performance small block Chevy round track engines, I've found that aluminum heads actually rob a lot of the combustion heat to the cooling system, instead of putting that energy to the pistons to help drive the car. They're great for extended full-throttle high RPM operation, like on a high-banked round track where the engine stays wide open and wound tight for extended periods of time, or maybe on a boat engine that spends hours at full throttle. For a street engine- - - -I'm a little crippled since I dropped a Honda Gold Wing on my left leg, but I think I could still outrun you if you tried to GIVE me a set of aluminum heads!
Jerry

Hotrod Lincoln is right, I worked for a race shop in N.Georgia for over 15 years that built some of the most awesome inline Chevy 6 cylinder drag engines ever. We also built most of the engines for the areas Southern All Stars dirt racers as well as many other series. And one thing I learned is that even with some class restrictions in those dirt classes limiting you to cast iron heads, the GM Vortech and Bowtie cast iron heads still easily would achieve 500+ HP without porting or a lot of expense.

I too have spent way too much time with a noisy, smelly, messy, love to burn you dyno and have noted this. On billet aluminum heads and blocks that have no cooling jackets equal power can be obtained in relation to iron counter parts. We make our own for the pull truck and tractor so we can control each step of the process and make changes if it offers improvement in power or durability. On heads with coolant passages the more timing and compression that can be used with the aluminum without detonation makes the power output on par with the iron heads. BUT, as Jerry said, the very reason more timing and compression can be used is because the heat (power) is being carried away so it's a wash. When it comes to durability on high mileage street driven machines using the old generation 1 heads and blocks then iron wins hands down. Now when one gets to the LS series GM and the Modular Fords then it's a whole different story. All the sensors, monitors, control modules, and computers can keep the combustion process precisely correct no matter whether it's iron or aluminum and do so for several hundred thousand miles. I'm one tick from 80 years old so I'll GLADLY hand off this rats nest of circuit boards and wires to the next generation of rodders.

I used to build some sneaky-Pete cheater engines for the claimer-class cars. Since the 64CC camel-hump heads were illegal for that class, we would take the 76 CC low compression heads and do a .100" angle mill from the spark plug side of the head where the majority of the combustion chamber volume was located. The result was a 60 CC head with a 76 CC casting number. A set of 1.6" exhaust valves and some pocket porting resulted in an engine that would outrun one with the camel-hump heads, and the tech inspectors had to do a full teardown to catch us. Like Smokey Yunick used to say, "It's only cheatin' if you get caught!"
Jerry

There are much better heads out there than the Patriot heads. Nothing at all wrong with aluminum heads. There are advatages to them, weight loss, easily repairable, much MUCH better port designs over anything GM ever made. The whole iron keeping the heat in is true, but this is why you run slightly higher compression with aluminum heads. Take a look at the Blue Print heads, Jegs brand heads if you are looking for a budget aluminum head. Don't shy away from a set of used name brand heads, like Dart, etc..

Ford tried mixing cast iron blocks and aluminum heads in 1937- - - -didn't work then, and the concept hasn't improved in the decades since. Some folks just haven't got the memo yet!
Jerry

I'm hoping you just like to hear yourself talk, lol. When's the last time a Corvette left the factory with iron heads? Technology has left someone behind. Maybe someone's a grumpy old fella? Aluminum heads come on almost everything these days. Please explain how and why aluminum heads and an iron block won't work? This should be great, lol.

Be careful what you ask for, pal!
Jerry

I've seen this argument spin around & around here & on other forums. Granted, I think that sometimes (IMHO) there is too much grumpy old man stuff on this sub-forum᠁on the other hand (and I'm 66) there is some good advice on this thread. Aluminum heads on pre-LS sbc motors? GM it started to happen in the 80's, first with race-purposed motors and then in production with the 86 Vette. I think most will agree that this approach didn't achieve real success until the first LS engines. Both Hotrod Lincoln & coilover have some good advice on some cautions regarding the use of aluminum heads on 1st gen (or iron Vortec) SBCs. Reliability with aluminum castings was finally addressed with the LS series in a computer designed & managed system as coilover described - something that was not done with 60s-80s motors. If you want reliability with power, you can get 400hp or more building up a crate with iron heads. You can read a lot about the history & get good advice on building up SBCs on the superchevy.com website. I generally followed some of their builds of crates to develop mine᠁

᠁I went to 325-335hp with a crate by massaging the heads & changing out the cam & valve train (plus headers & some other things). With a more aggressive cam and more head work or working up some Dart cast iron heads, I probably could have easily approached 400hp, but I've owned/driven enough vintage GMs with 300-375hp sbcs & it's enough for me. I get good gas mileage (on regular) & terrific acceleration. This is thanks to a motor that peaks without having to rev the [censored] out of it - that's because it's matched to a tranny & rear end made for this type of work. Things like power curves & gearing matter a LOT - but many ignore that.

᠁then again, I've found that bigger numbers or claims of being the fastest gets the most interest/attention᠁Have you gone 100mph in your modded AD? ᠁not for the faint of heart or something I recommend᠁My .02 worth.

Good advice- - - -and I'm not interested in, nor intimidated by insults by a newbie with 9 posts whose parents were probably filling their diapers when I built my first round track engine.

I routinely get 600+ HP on the dyno, (not some computer pipe dream) with cast iron heads. Anyone who understands the problems with sealing gasket surfaces between cast iron and aluminum due to different expansion rates will understand my opposition to aluminum heads on the street. On a round track race engine that gets run less than 1,000 miles between rebuilds, or a drag engine that only has to make it 1320 feet before it explodes, it's a different situation.
Jerry

Jerry is completely correct!! Iron heads are the ONLY way to go for increasing the HP on the street!! Unless you are planning only to drive this vehicle at full throttle for 1/8th or 1/4 mile runs, I'd go with fully prepared iron heads. Give INDY head service a try. Great tech staff and customer service...prices are most reasonable.

Tim