I'm buying an 86 iroc tomorrow that is an original 305TPI car that had a 350 short block put in it last year. Otherwise its completely stock. I've got an uncle that has a set of L98 cast heads that have been ported/polished with Comp 1.6 roller rockers. I want to get the LT4 Hot cam also. With the heads/cam and supporting mods I should be able to get 400hp right, or am I dreaming? I have no idea about the 350 short block that was put in it. It was a ladies car so its probably just a GM crate with nothing special in it. Thanks

Phyte

 

that will never hit 400hp. unless you're using a power adder that you didnt mention or somthing...

 

I read part of the tech article on this site about fully ported/polished L98 heads and they got 420 hp if I remember correctly. I'm not talking about rwhp(sorry). More like 340-350 rwhp is what I'm looking for, then the ATI will be put on the list.

Phyte

 

what article was that!?

heh, perhaps if you swapped in a huge cam, and had the springs to match it... then yea, 400crank HP is possable.... but otherwise, i dont see thoes heads (even ported) and a GM hotcam making anywhere near that.

 

Here's a thread talking about it with flow numbers:

https://www.thirdgen.org/techbb2/sho...ight=L98+heads

L98 cast heads 083
numbers are:
Lift Intake Exhaust
.1 63.8 41.4
.2 120.6 88.2
.3 178.9 124.1
.4 215.2 154.3
.5 240.1 171.8
.6 241 180

I didn't bookmark the article and search isn't being friendly right now. Its a 4 part article here in the forums that somone did. The numbers above are from that article

Phyte

 

Here's the article.

https://www.thirdgen.org/techbb2/sho...n+head+project

Phyte

 

just because the head can support 400hp doesnt mean you will make it.


first off, a TPI will choke off the air before you can make that much power. so another intake is in order...

second, you would need a bigger cam...

and last, headers and exhaust to let that air out...

oh.. and you would have to figure out what your compression would be too...

 

Dream'n. To make alot of power you need the full package. The heads, cam, and valvetrain will be nice. But like MrDude_1 said, you still need to think about the rest of the combo.

 

those ported l98s flow pretty damn good.

here is what they flow stock
.1 56/49
.2 120/96
.3 160/123
.4 186/140
.5 196/155
.6 196/155

yeah, ummmm if you do have 260cfm intake flow, with headers intake good cam (not a GM "hot" cam), it would be quite easy to make 400hp.


adam

 

Check out this post for some flow ratings. I'll sum it up for ya:

Stock TPI flows about 200cfm
Moddified TPI flows about 230cfm
Super Ram flows about 245-250cfm
Stealth Ram flows 275plus (300cfm with port work)
Mini Ram flows about 280cfm

 

I would measure your piston downbore (if they are flat tops) and cc the chambers on those cylinder heads to figure out what compression that you have and go from there. The LT4 hot cam is not a very radical cam, I would go for something a bit more extreme.

 

Those are the al. heads aren't they? I didn't think the iron flowed that well.

Or are the 083's the al. heads?

 

those are the aluminums, however if i remember correctly the irons have similar or (BETTER?!) flow.


adam