Originally Posted by Jrp1978

Go with afr heads and call Gabe Ray at Comp and he will spec the cam free! Afr v230 heads mine are p and p but they will push you well past 550 with a good cam and Intake setup!

Originally Posted by pharmd

Like I said before...this is something you might want to consider...

https://ls1tech.com/forums/dynamomet...-714hp-na.html

Originally Posted by 87silverbullet

That motor was 13:1 comprression and runs on e85. The OP might not want that much compression and might not have access to e85 (like me).

Now here is an engine that is on pump and has L92's. It also has a stock intake which is a disadvantage compared to the vic jr. Just imagine if this engine had a vic jr?

https://ls1tech.com/forums/dynamomet...o-results.html


https://ls1tech.com/forums/generatio...ml#post6694298

Now also imagine if this engine had the small bore LS7 heads from PRC or RHS on it, which weren't available when your link or my links were made. It would most likely be on the *** or equal to that 714 hp motor with an LS7 small bore and single plane intake

Originally Posted by pharmd

Yes I understand the OP may not want that level of compression and reliance on race fuel. However depending on its intended use and car its going in, this motor shows the power potential of these AI L92's. An 11.5:1 up to as much as 12:1 have been successfully run on 93 octane. This would only result in a small reduction in power over the numbers posted in that thread. In fact, again depending on his use, the argument could be made that by running a larger HR cam or jumping to SR, you could result in minimal power loss over this motor.

I would caution against picking a popular-trendy set of heads, like some mentioned in this thread. Their are so many variables that go into making power. I ran the brand new PI 11deg cathedral head 215cc on my stock sb ls1, those heads had huge fanfare, superior valve angle etc. It didn't make as much power, nor was as drivable around town as the AI 5.3 218cc head (using same compression same cam same intake same exhaust, same tuner same dyno same weather). I would encourage the op to collect research. Talk to those who you know by reputation, that are more about helping you find the right part vs selling you a popular high margin option.

Originally Posted by 87silverbullet

The numbers of that motor would be very peaky with a single plane intake which would require the OP to have a big stall and gear to race with and make it more track oriented unlike what the OP just posted. Yes you can run 12:1 on pump, but L92 heads have shown no increase in power in going to that much compression.

I wasn't suggesting that he needed to run that much compression, just that it "could" be done to bump power. A 1 pt increase in compression IIRC is about 4% gain in power. A simple calc of DCR would afford the OP to know how it would fair on pump fuel.

11-11.4 is where you want to be with them on pump. Also, depending on the OP's car, the vic jr might not be an option. So he would be restricted by an intake that has to fit the car. Any style ls intake has it limits so going to 12:1 or SR is null and void because the intake will hold it back from letting that characteristic shine to its full potential.

I didn't really read into what type of car this was going into...so I don't know what intakes he has access to. Regarless based on results I have seen, the type of increase in power from 4500- (both in HP and TQ) should offset any reduction in TQ below that number. The RPM drop between gear changes can be calculated based on trans and rear gearing to determine the ideal HP/TQ curve. But from what I have seen large increases in HP and even added TQ (even with a low profile elbow stuck on a single plane) can make this a formitable combination for a range of cars. I must apologize as I didn't read throughly his post about desired usage of the car, I just replied based on the fact he wanted to make the most power he could on a "drivable" combination, without breaking the bank with exotic parts.

Down the compression of that motor, put an LS style intake on it, and change the cam and watch that AI headed motor make the same power as the PRC headed motor.

As far as the heads I would put the PRC L92's up against the AI L92's any day.

I wouldn't. Head for head (243, 5.3L, L92) I wouldn't. I only speak from my personal experience in running a few different brands of heads compared with AI, factoring in the purchase expense. Im not knocking PRC or any other vendors heads, I just feel AI is a superior product (whether its porting factory or aftermarket castings.


They are both great heads and do really well. I've never mention any popular or trendy head. I have put up the PRC and RHS LS7 small bore which have yet to become trendy because they haven't been out long enough. One guy here has them on his 429 in a 5th gen camaro and is making great power.

The small bores have been around for nearly 2 years. With folks placing so much emphasis on flow #'s, this type of head has garnered alot of attention. Im sure they can make great power. Their aren't a plethora of results out there, at least that I have seen. That is why I restricted commentary to parts with a longer track record. Their are number of options available to him, in the end he will have to factor in plans for the car, with budget and power goals, and make a decision from those factors. I simply was giving him an example of the potential of this particular head on a similar sized motor, allowing him to extrapolate power potential based on factors relative to the specifics of his demands.

Originally Posted by arliejr08

I'm between the trick flow 235cc and the prc 265cc either way I'm gonna get new rockers so which would u run?

Originally Posted by 87silverbullet

If you run AFR's then you are going to want to get a FAST intake because there is no factory cathedral intake that is going to flow the air for a 418.

The good thing about AFR's is that you can run the stock valvetrain unlike Trickflows because of the different valve guides.