I will go ahead and ask another age old question. I know this has been discussed before, but I'd like to know opinions. I've looked over the market for heads, and came to a half decided conclusion. I am building a 408 with 90/90 intake and around a 10.6 compression. The heads that I first looked over were AFR's and TEA. TEA's price is way on up there for a set of heads, which I'm sure they are quality. But, I looked into the AFR Mongoose 225 Strip heads and really like the flow charts on these. If these would be great, what size cc chambers 62, 65, or 72? Is this over kill for a 408 on the street? I am aiming for at least 500RWHP, but really want 550RWHP as my main goal or more if it can achieve. Please give me any input of possible heads that flow as well as these...

 

L92s from my opinion

 

Just another thought... If L92s which intake 90/90 or L76?

 

If you go L92, you have to use L76. FWIW you can get the complete L92/L76 topend for less than the AFR/ET/TFS heads.

 

if you dont really want to spend the money then go with the l92, l76 stuff. but i cant complain about the afr 225's i got 567/528 on motor.. but higher comprassion which by the way i would recomment you go with closer to 12:1.

 

If you want the best performance then it'll cost you $$$. If you want the best bang for the buck then it'll cost you RWHP. That said I went for the best performance for my 408 project.

ETP LS7 heads for a 4.0 bore and a LS7 intake. This will out flow a fast 90/90 and for $3200 the heads had better be the best damn heads out there

 

you could hit your hp goal with the L92/L76 setup it just depends on how big of a cam you wanna run. from what i understand these heads and the right cam can be very streetable, but for BIG power you gotto shell out the big bucks.

heres a recent thread where someone dynoed a 403 with a decent sized cam and he made 551whp and over 520 ft-lbs....granted it was on a corvette (less drivetrain loss) and im assuming its a 6 speed. but you can see from that that they make great power across the board and for *untouched* cast heads those are awesome numbers for a great price.

https://ls1tech.com/forums/generation-iv-internal-engine/652763-my-403-ls2-l92-l76-finally-running-video.html

 

sweet....so your runnin the LS7 heads on you 408? i found flow #'s for the L92's, but how much differant are the LS7's?

 

The motor is being built at New Era Performance. I won't actually have it installed and running in my car until the spring.

But here is a link to ETP's website. Just click on products/performance and then click the LS7 4" to get flow numbers. After talking with Cary @ ETP he assured me that a 408 will make noticeably more power with the LS7 heads/LS7 intake then a setup with say ETP 240 heads/fast 90-90.

http://www.etheads.com/mainpage.htm

 

ET 245`s on mine. They flow there ***-OFF!

 

wow....looks pretty dang good....might change my l92 setup for the ls7 set-up.

 

I'm still trying to decide between ET/TSP/L92's myself. I'm still waiting to see some numbers from the CNC'd L92 's and have yet to see any numbers from TSP/ET with a big cam. So far everyone is doing their strokers with nice heads and conservative cams. I don't plan on going conservative on my buildup