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Just got my head suggestion form back from AFR. Opinions?
Hello all, I have a 2003 base Corvette convertible with the LS1 and 6-speed manual. I did the basic bolt-ons (long tubes, catless x pipe, ram air intake, and a good tune) and now I'm plotting to do a cam and new heads.
I plan on getting the BTR LS1/LS2 Stage 3 N/A camshaft because it's a good power increase but still has decent drivability. When it comes to cylinder heads, I had almost no idea of what to look for. I want good power, but I don't want to have to do a ton of other mods to make it reliable and run well.
It sounds like AFR has a really good reputation, so I filled out their cylinder head recommendation form and they recommended these:
Does this sound like a good way to go? As I said, I'm very new to this, but it threw me off to see an LS3 cylinder head recommended for my LS1 and all the LS1 cylinder heads they sell say 15 degrees and this is 12 degrees.
Also, as this is my first post, here's a picture of my car
Did you specify they would be going on a 3.89" bore LS1? Because those heads they suggested only work on 4" or larger bore (6.0 or 6.2). I would think an AFR 215 would be adequate for what you want to do, only thing is with AFR heads they tell you to run roller rockers which is another added expense..just something to think about.
Yeah, the questionnaire you fill out is very specific and it asked what engine, bore, etc.. I reiterated that it is a stock 5.7L LS1 in the comments box. That's why this recommendation confused me. Glad I didn't just click order and start tearing things apart!
Wouldn’t use those recommended heads on a 5.7. I’d go with the 205’s-215’s max depending on usage. Street car would definitely get the 205’s
Also wouldn’t be a bad idea to set the quench just takes a couple tools,math and gasket thickness choice. You’re gonna need to measure pushrods also. A custom spec’d cam to match the head choice also wouldn’t be a bad idea.
Have you considered having a set of factory heads ported?
There's some pretty good results using stock heads or even better with the smaller chamber 862/706 heads from places like Texas speed, and you wont have to run fancy useless expensive rockers.
Not sure why they'd recommend LS3 heads. Did you tell them you wanted to upgrade your intake manifold too? Your current LS1/LS6 manifold is cathedral ports and the LS3 takes rectangle ports...opening up additional issues. As others have mentioned, the LS1 215 or 230 heads would work great for your intended mods.
Or better yet, reach out to @Tony @ Mamo Motorsports for his suggestion. I believe he starts with AFR cores and upgrades them to his specs. He can spec a cam that will work for you too...
Yeah, the questionnaire you fill out is very specific and it asked what engine, bore, etc.. I reiterated that it is a stock 5.7L LS1 in the comments box. That's why this recommendation confused me. Glad I didn't just click order and start tearing things apart!
They made a mistake....you cant even physically run an LS3 big valve head on a small bore engine and it would be a complete turd even if you could.
I was the head of R&D and Product Design there for 15 years.....I went on my own the end of 2014 and I run Mamo Motorsports full time now. I can help you with a complete very optimized package that will have all the parts working in harmony with one another (that's the key to getting great results). I can help you with the correct AFR heads or a Mamo Motorsports head that flows even more and comes with lightweight hollow stem intake valves and other perks. Just a matter of us meeting your budget and your power goals.
Probably the best thing about my involvement is you not having to question anything....I have been doing this for over three decades and Im very good at what I do
You can PM me of course but I prefer you shoot me an email or pick up the phone.
Beautiful car btw....its deserves a really awesome powerplant!
As Tony knows from his C5 days, 205cc intake runners with the right compliments can make for an LS1 powered car that runs low 11 seconds@124mph 1/4 miles...
Tony has proven repeatedly- A big cam will gain X amount of power, big heads X amount of power, BUT a COORDINATED SET of SMALLER heads and cam will do more than either in the previous statement, giving you a far more tractable build with more power ACROSS the band
It's about velocity. Maybe an exaggeration, but that velocity acts as a form of supercharging, via the air's inertia "ramming" itself thru the smaller ports rather than a larger slower charge relying more on atmospheric pressure to get it thru the larger port.
Tony definitely knows his stuff and won't steer you in the wrong direction just to make a sale. I used him for my 402 build while everyone was telling me to use LS3 heads, go with small bore LS7 heads etc. and while I did question some things I went along with the plan and it payed off big time. 660+hp at 6650 is a great number but over 500ft lbs of torque from 3000-redline.. definitely takes a good understanding of needs and goals.
My C5 is living proof. With the 205’s, 226/230 114 cam Fast 102 90mm TB etc it ran 10.99@123.4 in good air. A4 car which costs a bit of mph.
All those same parts in/on my 6.2 short block goes high 10.70’s at 126+ in normal air.
Folks told me the 6.2 would run the same as the 5.7, heads were too small. 😊
Good airflow with small runners flat works.
Living proof that some "folks" need a bit of an education!! Frankly, I have never seen a larger engine running the same equipment as a smaller engine engine still run the same as the smaller engine!! Everything being the same, it would be virtually impossible when you throw physics into this equation! Almost like saying 3lbs is lighter than 2lbs!!
It's about velocity. Maybe an exaggeration, but that velocity acts as a form of supercharging, via the air's inertia "ramming" itself thru the smaller ports rather than a larger slower charge relying more on atmospheric pressure to get it thru the larger port.
I'll give the OP a perfect example, Gary. Back in '05, very few aftermarket heads were out then, because the ported cathedrals were so good. AFR just came out with their 225s. I put them on my Darton 427, with an LS2 90mm TB, and FAST intake. Sure, they were a bit small for a 427, but they were the only game in town. Talk about velocity and midrange torque......I now have an LS7, with LS7 heads. The 225 headed motor felt half again as fast as my current LS7, got 5mpg more (at least), and traction with 315/30/18 Michelin PS2s was nearly impossible. When the A4 C5 hit 2nd gear@about 70-75mph, the car went sideways, almost every time. Heres a funny stat; my 1/8 mile time/speed was almost identical to my stock LS1. But it picked up 35mph in the last 1/8 mile!!!
I'll give the OP a perfect example, Gary. Back in '05, very few aftermarket heads were out then, because the ported cathedrals were so good. AFR just came out with their 225s. I put them on my Darton 427, with an LS2 90mm TB, and FAST intake. Sure, they were a bit small for a 427, but they were the only game in town. Talk about velocity and midrange torque......I now have an LS7, with LS7 heads. The 225 headed motor felt half again as fast as my current LS7, got 5mpg more (at least), and traction with 315/30/18 Michelin PS2s was nearly impossible. When the A4 C5 hit 2nd gear@about 70-75mph, the car went sideways, almost every time. Heres a funny stat; my 1/8 mile time/speed was almost identical to my stock LS1. But it picked up 35mph in the last 1/8 mile!!!
Man, that is off the hook! Proof of what flow velocity does. Flow is good, but moving it fast is way better!
01-27-2023, 06:12 PM
Just got my head suggestion form back from AFR. Opinions? 
