FostersPerformance

Hi and thanks...
Im not gonna start a huge discussion here, just a basic question.

Im fully building an engine for my 88. Around 450hp mark, give or take. I have a choice of building a NA, FI 383, or a blown 350 EFI. I have my l98 heads, and when you look at the GM 383 engine, it almost seems the same 'small' head as the l98.

So my question is, will the l98 heads, professionally built, support a NA 383?

I dont want to buy heads if i dont need to, but i also dont wana dump alot of money into the stock ones if they wont support it.

Like i said, didnt want this to turn into a huge head discussion, just was curios.

Thanks all!!!

0RPP_Corvette

You shouldn't have any problem improving the stock heads for the 383 setup. You will be limited by the stock intake at higher rpm.

FostersPerformance

No stock anything lol...Only the stock block casting (highly modified) and the stock heads (just the castings, nothing else). They were the only 2 things ive kept from the l98.
Alot of guys running these heads with different intakes? Like i said, i just worried about the small valves, and intake runners if it will support 425-450hp.
And with a blower i worried about the small cc's of the head giving me too much compression. Actually, i worried about that with the 383 as well, but figured id deal with that if i decided to run these heads.

Thanks again

84wannabezo6

You can fit 2.00 intake and 1.56 exhaust in there but I was surprised at the difference beteen the stock valves and the manley street flo with undercut stems that I ended up using. The stock valves had a ridge on back of the valve instead of a nice angle. I dont have a flow bench but you can tell there is a big difference.Look at John Lingenfelters book on small block mods He liked those heads.

Mike 92LX

Stock L98 heads can be made to support 383s easy on motor and pump gas. TPIS,LPE etc used to do it all the time. With a good porter, matched cam and intake you should be okay. Keep will be the intake(runner length) and cam duration-have to make sure they compliment each other.

Now is the time to decide if you are going to run forced induction or not...

GREGGPENN

Thicker decks, better oiling, and heavier castings are the main selling points of a head (like AFR) over stock-improved heads. With the cost of FI compared to the price-increase of ported vs. AFR, I don't understand why you'd even consider using the stock heads.

I'm thinking it's only about 10% of your blower cost -- added on top of ported 113 (stock) head price -- to get into a head specifically designed to hold up to the demands of FI.

Even on a stock build, I don't think there's a ported (even CNC-d TPIS porting) that can equal the 195's.

My opinion is the 113's are great, can be ported well, but can be beat (and should be beat) for anyone serious about building.

You sound serious. (except that you didn't say FI and 650hp in the same sentence! )

FostersPerformance

Believe me, keeping it around 450hp is almost like im compromising lol.....I build big block marine engines all in the 'mild' 600hp range. But i know anything over that is a waste on the street.... Met a guy last year with a brand new ford gt 500 modified to 760hp. The guy couldnt grab traction to save his life. He actually regretted it, saying it was a waste...

Yeah, i might go with the AFRs, and build the l98 heads for another engine. Got a PM from a AFR rep, gonna consider it..

Thanks everyone for the advice!

cv67

For the money you can beat the AFR head
What is going to cost to completely go through your L98s with big valves guides seats etc etc I bet you spend as much or more on old castings that dont compare.

450hp with stock valves on a tpi never happen period no matter how much porting.

383vett

If you are going to keep it at 450hp, why bother with FI? You can easily build a 383 with those horses without going through the expense of forced induction. A good induction system, cam and heads will get you there in a blink.

FostersPerformance

When i said FI, i was meaning Fuel Injected..Sorry for the confusion...Planning to build a fuel injected 383. I ditched the TPI long ago. Still for sale actually..

383vett

Got it!

65Z01

If you do go with the 113 heads I suggest installingnew seats with 2.02"/1.60" performance valves, 5-angle valve job, etc.

Both TPIS & David Vizzard have flow numbers on stock & worked 113 heads so you can see if your 450hp target is possible.

FostersPerformance

Glad I waited..Just got a set of GM performance fast burn aluminum heads for free!!!! SCORE!!!!! Even came with steel comp cams roller rockers 1.6R...Came off a boat with a cracked block...So I guess the L98's will be sitting a while. Thanks everyone!