claus290373

Hello
I have a 350tpi (l98)with hooker 2055 and cat delete everything Else stock. I want some more power and have a offer on some vortec heads. But will it work with my engine/ tpi ??
Know i have to buy a new intake

Thanks Claus

MoJoe

iTrader: (5)

Yes. With the same 64cc-ish chamber, your compression should remain the same. You know about the intake.
The stock cam will not exceed the head's .480" valve lift limit. There are many threads documenting how to increase the valve lift limit with springs, retainers, keepers.

2005Impalla

I would not bother with it. I would replace something else. The cost of getting the heads and new lower intake is not worth the power you might get. You have good heads. I would swap the whole intake for a stealth ram intake, do a cam swap and have it retuned. Would cost about the same and yield more power. Also your swapping iron heads for aluminum. Your going to gain about 40 pounds on the front end. Your stock intake is the largest restriction on your car and if you doo swap to the vortecs and get a new lower also get larger runners or there going to be the bottle neck.

MoJoe

iTrader: (5)

Camaro/Firebird L98s came with iron heads. Your statement to the contrary may* be true with a Corvette engine.
*I am not up on my Corvette engines to argue this point.

As to your other point, the Vortec heads ARE an improvement over stock. The Vortec compatible intake the OP buys could be a stealth ram.
Weiand Stealth Ram intake for vortec heads. Add fuel rails and a FPR (fuel pressure regulator). That would cost about the same, or maybe a little more than a Vortec TPI base, and would provide higher RPM capability than TPI. The factory TPI cam would need to be upgraded to take advantage.

2005Impalla

my bad I thought all the L98s were aluminum heads.

Night rider327

iTrader: (13)

Yep only covette got the alum L98 heads. F-body L98 heads are iron.

The iron L98's ain't bad, but ain't good. They are the best of the bad 1980's and 90's production gen 1 heads..

But the vortec heads are the best production gen 1 heads of all time. They will gain you a good 40 HP over your stock L98 heads.

The only prob will be the vortec style intake that's needed, but the fix for that has been posted by MoJoe

2005Impalla

We will see how well these vortecs are. I am building a vortec 350 as we speak Wish it was TPI though.

2005Impalla

Are the L98 iron heads still 1.94/1.5 with small chambers? Do they have the 87 and up iron head bolt pattern or do they have the 86 and older bolt pattern like the L98 aluminum heads?

InfernalVortex

iTrader: (4)

Iron L98 heads are fine. They're not amazing by any means, but they're the best after Vortecs in my opinion. They're definitely not the bottleneck of the L98.

Fast355

iTrader: (2)

After the exhaust manifolds and exhaust system they are the next bottle neck of the L98. The only difference between the GM 300 HP 350 HO and the GM 330 HP 350 HO was the swap out of the "217" casting heads for the "062". The 217 casting is identical to the 083, just a revised number used on marine/crate engines. In 1999ish Hotrod magazine removed a set of 882 smog heads off a 1976 Impala 350 and put a pair of 083s on the engine. With the mild cam, Q-Jet and headers the 882s made about 275 HP. With the 083s they made 299 HP. With a Comp XE268 they gained 20 HP to 320 HP. They then junked the 083 heads for Vortecs and the matching Edelbrock Performer intake. After a little tweaking they made 375 HP and an equally impressive 400 lb/ft of torque. Vortec heads really are that much better than the 083 heads. IMO even the 193 TBI swirl ports are better than the 083s, stock for stock. The Ramjet 350 has a milder cam than L98 and yet makes more HP.

I recently put a set of these Vortec heads on a Vortec 350 that had cracked heads. The engine is stock other than catback dual exhaust, these heads and 1.7:1 roller rockers. No complaints here, runs great. Will know more about the long term durability of these heads as time passes.

http://www.jegs.com/i/ProMaxx-Perfor.../2151/10002/-1

midias

I got a set of those back when they were called patriot heads. No complaints here they seem to run great.

Fast355

iTrader: (2)

No complaints here either, atleast not yet. For a 5K lbs SUV running on the stock computer tuning using the hideous stock intake/injector design it moves quite well.

InfernalVortex

iTrader: (4)

Ive seen way too many 083 headed 350s put down decent power with a better cam and intake. Im with you on Vortecs being way better, though. The TPI is more specifically what I was referring to as the bottleneck. Im not a very big fan of it. You just cant cam an L98 with 083 heads and bolt ons to its streetable potential with the TPI on it. You throw a carb or a stealth ram on there and there's a lot more available.

I know you're a fan of the swirlport heads and I know you have good reasons for it, you're a sharp guy with a lot of experience. But after seeing the flow number charts I just dont share your enthusiasm for them. The exhaust ports may be good, but the intake ports aren't. I'd argue that the swirl they produce must make up the difference, but I haven't seen any put down good numbers at the track either.

Either way... I just have an issue telling the guy to buy a Vortec base and vortec heads (That's quite a bit of money) and putting a stock TPI on top of it... that's just going to kill potential, but maybe I just have an irrational hatred for TPI. You'd be better off buying aftermarket aluminum heads, but even then with the TPI on top and factory cam... you're not going to be making a whole lot of power.

Night rider327

iTrader: (13)

The 083 casting iron F-body L98 heads have 64cc chambers, 1.94"/1.50" valves. My info shows 194 cfm intake flow and 118 cfm exhaust.

The Corvette L98's are still 1.94"/1.50" valves, but 58cc chambers and my info shows 199 cfm intake / 159 cfm exhaust

ray jr

iTrader: (2)

anyone know how the promaxx 2151 heads flow ?

midias

According to promaxx / patriot they flow decent 240cfm at 500 lift and 185cc intake

ray jr

iTrader: (2)

thanks midias .. any complaints with the heads ?

midias

They have been good heads, I bought them when they were the patriot name. I had a valve spring dampner break. It was my only issue. Promaxx was very good and replaced it asap at their costs. Search under my name for patriot 2151 for some threads I made. They made a ton more power over my 882 heads. I would buy them again.

When I get off my phone I will look for the threads with pictures and install notes.

claus290373

Ok want the stealth ram intake, but dont think there is any place here in Denmark that can do a retune 😂
I only use the car 6 month( sommer) and was thinking to swap the tpi to carb. I dont care about mpg and it will be easy to tune at my Local shop.

midias

I would learn to tune it your self and find a dyno shop. But it can be done.

As for the links I promised here.

https://www.thirdgen.org/forums/tech...eads-pics.html

https://www.thirdgen.org/forums/tech...ted-heads.html

claus290373

Ok could use the Winther here to learn how to tune but where do i start ? Any good books or websites thats good?

midias

The DIY prom section of the board has lots of info. This link is a great place to start
https://www.thirdgen.org/forums/diy-...uide-book.html