does anyone run these kinda heads with a 408? i have GTP S2+ 5.3L heads with 2.02/1.57 valves. if i upgrade to 2.08/1.6, can these heads be capable of feeding the 408? any info will be appreciated.

 

I've done it before, but 5.3's are not the best heads because of the smaller chamber size.

 

Futral Motorsports has used them on bigger motors. They used them for a 434ci Mild Solid Roller setup and it dyno'd 550rwhp/510rwtq. Just recently they used TEA 5.3L heads on a 396ci and managed to dyno 503rwhp thru a 12 bolt and 4.30's with a cam much smaller than the TRex used in Jason99TA. Dont ask me the cam specs. Call Futral. If I were you I would go with 6.0L heads. You should have no problem selling your GTP's.

 

Stg 2 TEA 5.3l made 503??

 

You will have to call TEA for the particulars on the heads..

https://ls1tech.com/forums/showthread.php?t=150926

 

sell these heads???? thats a sacralige(sp?).hehe. i really dont wanna go through that hassle. besides, these heads flowed like crazy with the 2.02/1.57. wont the smaller chamber help make power by build up the CR? GTP has my heads right now,i am still undecided what upgrades to get. maybe S3, just valve upgrade...its all up in the air.

 

What did Craig say? He knows his heads.

 

I also saw futral get over 500 rwhp with a set of 5.3's on a 396. I would still say go with the 6 ltr heads though.

 

No, do not do it. Some 5.3's have made decent #'s on big motors, but those heads were NOT designed to be opened up to a big bore. I would go with a 6L head at least, the 5.3's will start dropping off quick after .500 if opened up to big...

 

craig said " hey cat, i can make those heads flow 340+, but its gonna cost $$" he is cool,but i think i will look into the 6.0...maybe

 

damian, what would you consider the limits of the bore on the 5.3?

 

Just do it Captain Catdaddy!

 

you know whats up...Cat.

 

No one is saying you cant use the 5.3's. Look at it this way. Say Craig hooks you up and you dyno 500rwhp/500rwtq. If Craig did a set of 6.0L's you would dyno 520rwhp plus. I know things are not cheap, but why skimp on the power making things? Heads are VERY important.

 

TTT for me..

 

I am not yet up and running but I sent a set of 5.3 heads to LPE for my 408. They are on there way back to me now. I got 2.055I...1.6E valves with dual springs. They told me that valves bigger that 2.055 are too heavy and can break. I expect the valves to be more than big enough as a friend of mine has dynoed 500 rwhp in a c5 with 2.02...1.6 valves.

 

Ditto ,, Its possible that you might make good numbers with the 5.3's but you may as well go with the 6 ltrs to be sure.

 

I would use LS6 heads if possible. If that is not in your budget I would go to the 6.0 heads and get some compression out of them. LS1 and 5.3 heads are not the best setup for a 408 IMO. They will work though.

 

If you are using a flat top piston in your 408 your CR will be to high. With my TEA 5.3's that were milled to 60cc the CR would have been over 12 to 1.

 

Yeah I never thought of the cr issues. Besides the possible port stalling that has to be taken into consideration as well.