Hey hows it going? I have an '89 GTA with the L98 engine currently bieng rebuilt and with the current mods: Crane cams cam (not sure of duration), 1.6 roller rockers, hedman shorties with 2.5" collectors which flow into an y-pipe with single cat and out a flowmaster 80 series crosssflow muffler, MAF sensor with screens removed, ecm chip which I didn't know it had until I came across it a while back don't know anything about it! and a port and polish job which I didn't know it had either and was discovered by my local machine shop ! Now that my engine will be running like a champ soon, I want to mod it some more and shoot for atleast 400+ rwhp. Near future mods include a 3" true-dual chambered exhaust with hi-flow cats (if possible), TPiS mini-ram manifold, underdrive pulleys, MSD dizzy, and some other goodies I can't think of right now lol! At the moment, I'm looking to upgrade 2 major components: 1) Headers shorty or LT's with ones that have 3" collectors; not sure what primary tube size to look for yet any suggestions and 2) Heads that will outflow my stock L98 ones. While I'm at it, I found set of 062 vortec heads for sale here at a local speed shop which are cut for .600 retainer clearance and viton seals milled .010; they have 64cc combustion chambers and flow about 239 @ .450 lift with intake port stock. Would this be a good combination for my engine? Will the headers bolt right up to the heads? Any info, advice or recommendation on a particular setup or on this head/header combination is welcome and appreciated! Thanks guys! Later!

edelbrock performer or etec heads or vortect head i'd say

Seeing as you have an automatic 700R-4 I would say stick with the shortie exhaust headers..... I put long tubes on mine and there just isn't alot of room between the frame and the tranny pan, then you have to pipe the exhaust under the tranny crossmember or fabricate a new one ( which I've been thinking about.) Check out the pics I've posted in the exhaust section (I've given others the same advice) It's different if you have a standard tranny, theere's way more room!!!!

Secondly, I've always read that AFR (Airflow Research) heads out performed everything else.
I think I'm gonna sell my SR Tourquers and get AFR's instead.......

Do a search on vortec heads. The intakes are different and have to match the heads.

400 rwhp is a bunch. 70's corvette 427 BB 435 HP gross, 348 net (as installed in car), and 278 RWHP (minus tran and rear end loses).

350 tpi na does not = 400 rwhp. need to have adders sc, turbo, and or spray

comlpletely wrong, you need to start reading some magazines, there are plenty of 350 tpi motors putting out over 400rwhp bro. Lol do a lil research and you'll see

I don't believe everything a Magazine says though.
There's often Real World #'s and then there's Magazine World #'s....... hehehe L98's can achieve big numbers, but they're usually big cubes and alternative intakes
400+ rear wheel horsepower is alot....... means 500+ at the crank???
and when you say rebuild what does that mean...... 355"??? compression ratio??? Crank, Rods???? Forged???
There's a recipe (or many for that matter) for reliable power

-Search "dyno #'s"

more like 475 at the flywheel but it would also depend on what dyno the vehicle is being tested on. And I've actually owned a 12 second daily driver iroc with a tpi 355, you just have to get the parts combination right. almost anything is possible with todays roller cams and high-flow heads

From the dyno testing we have done the AFR Eliminators are looking real good out of the box. I have heard the Dart Platinum series is supposed to be pretty good to.

From the testing we have seen the Edelbrock E-Tec heads have not flowed or performed like they should have out of the box. On the flow bench they were short of the advertised flow numbers. The AFR's were on the money if not better.

The Etecs will respond quite well to porting if you want to spend the extra money.

For future mods and 400whp on a 350, go AFR 195's with a big hydraulic roller cam and miniram easily. MAY beable to do 400whp with a HSR and similar cam, but i'll confirm that being possible when my HSR 383 is done. I'm shooting for 400whp as well.

GO with longtube headers, 3inch collectors. Miniram or LT1 converted intake with a Custom BRE cam like the LE3. you'll get 400whp. Gotta have 11 to 1 compression or close to it

"ecm chip which I didn't know it had until I came across it a while back don't know anything about it!"

The tuning learning curve.

yeah just listen to the guys oh and btw my engine builder said that the motor that was in my 12 iroc was had compression right around 10.1:1 and no emission bullshit

Just a minor detail, the car came with those mods when I bought it last year . As for the chip, The stock one was just sitting in the console which got me wondering if it was replaced with a performance one or just a "backup" chip. I decided to take a look at the ecm one afternoon, and discovered that it did in fact come with a performance "superchips" (or I think its called that) chip.

Yeah I've heard good things about those AFR heads also; I bet they even outflow the vortecs huh? About the headers, I'm not going against your advice but my personal choice was the shorties because of ground clearance and with the chambered exhaust system it will probably be an issue with LT's right?

Na its just the regular 350 block, I'm not an engine afficionado so I have no clue about the compression ratio. I do know that it is getting all forged internals! Hey I appreciate the info guys and thanks for not flaming although if you have to.. you have to lol! L8R!

vortecs are OK heads... alot of ppl make them out to be the best but they are far from it. they got a good chamber design, decent runners but with ok flow numbers. AFR's are far superior, from runner design to flow numbers to the valve train

If you can afford them, they are great heads for the high hp builds, and 400whp is a pretty stout build

exactly as he put it

Pandin knows his stuff, and I agree with him, I dont see alot
of 400rwhp L98's or TPI motors regardless of designation.
Reading magazines is your defense?

It's possible, just not common. Maybe your engine builder needs
to build me an engine

The super chip that was in one of the cars I bought seemed to run rich and have a little more SA. I had better luck with the stock chip.

Tuning your own chip for your own car will be a learning experiance but the results can be very rewarding.

The farther from stock you get the more important tuning becomes.

well i never got my motor dynoed but i know I consitently ran 12's with it.
TPI 355

hp=(weight/((et/5.825)^3)) 3500#/ ((12/5.825)^3) 3500#/((2.06)^3)

3500#/ (2.06*2.06*2.06) 3500#/8.75 = 400 hp thats at 12 sec flat

3500#/((12.5/5.825)^3) 3500#/9.9 = 350 hp thats at 12.5 sec

I support the AFR Elimenators are the best heads on the market for our L98 engines. Other heads that are a bit less pricey (maybe) are the 195cc heads from Patriot Performance, the other are the Trick Flow heads.

To support the heads, I would go with the HSR and a 52mm TB. The 52mm TBs with an airfoil flow about 900 CFM, plenty to make over 600 Hp.

Word of caution: I think that if you go with "vortech" heads, you MUST have an intake which is also vortech style. Can someone else confirm this for Phoenix. Be sure not to buy non-matching parts.

Also, for 400 RWHp, you must get a suitable cam. A 224/230 duration might be enough cam. Just dont over cam the engine displacement, it will be more difficult to tune. And do not go below 112 degrees on the LSA, 114 is most ECM friendly.

I appreciate that BRO!! Guess I didnt have 400 at the wheels

What's your budget?

Because this isn't a "slap on some heads" achievable thing, no matter what the 15 year old 305 TPI street racers on this site try to tell you.

You're going to need a bit of cam, a good set of heads (not vortecs), compression, major upgrade from the TPI. Forced induction would make this a lot easier. Either way, you're talking some serious cash to get it done, the RIGHT and RELIABLE way. Judging by what I read in your opening post, you have no idea (no offense )

Exactly.

I'm running a 12.8 on a motor that made 430 at the flywheel (dyno numbers in a magazine). My motor is sufficiently less powerful than theirs because I'm missing some crucial things like good headers (they had longtubes I have shortys), better carb, and roller rockers. I'd guess I'm around 320 at the wheels or 330. I don't know.

FYI I'm 21 almost 22, but yeah I ran a 12.56 at the time. And the guy asked what are the best heads, he didnt say what can get him to that power level

i could build you a 400whp combo. Just follow the miniram, LE3 cam, 11 to 1 compression, AFR 195 heads route. it will do what you want it to do.

I'm doing 383, 11 to 1, AFR heads, custom grind like a cc306 on steroids, HSR. hoping for atleast 400whp and mid 11 second slips

I agree with Orr89RocZ. If you are serious I would give Lloyd Elliot a call. He has some packages for the LT1 cars that can put out the 400rwhp that you want. Maybe just give you some free advice.

The difference will be that you will use a good Gen 1 SBC head such as the AFR Eliminator line instead of a LT-1 head. If he does the work for you, you will also want to send him the Mini-Ram for intake port modification to match the heads. You will also need to buy the supporting modifications for the motor such as the cold air intake system and exhaust system he recommends.

As to 400rwhp with a true TPI style intake system. I would love to see who did it and what parts they used.

My joke about age had nothing to do with you.

He needs a package, a build, not just a set of heads. Throwing random **** on a motor doesn't get you very far. Planning your build with all the correct parts, heads, cam etc and making sure they fit in your budget is how to get it done. He wants 400 hp. We could recommend a set of race heads that cost a few grand that would definitely get him there, or we could recommend a suitable cost effective setup to reach the goal. Right?

He was talking 350 cid vortec heads tpi and 400 rwhp read what his question asked.

I do not doubt that the 400 rwph can be done. but the op said he had a deal on a set of vortecs.

Best heads, cost or perfomance?????

no offense taken I just want to be clear that Im not some middle schooler that likes 3rd gens talkin out the side of his mouth and that I do have some experience with these cars. You do make good sense though, all of us pretty much agree on the same thing it seems like

Yeah they are pricey but if thats what I'm going to need to reach those hp numbers then I should start saving up for them !

My budget is about $1000 bi-weekly so I should have these bad boys soon right after my I get my polyeurethane bushing and front end upgrade ! Lol none taken, I had documentation on the cam which showed its duration but I lost it!

Yeah the Eliminators seem like the best decision for the hp's that I am going for. How good would a mini-ram perform with the heads? If thats the case with the vortecs then I probably can't use that type of intake since it has an integrated manifold huh? Thanks for the cam info...I know what to look for now ! Thanks alot for leading me in the right direction guys! Take it easy! later!

your gonna need to turn some rpm to hit those numbers, atleast 6000 rpms. a 224/230 cam could make it close, but its hard to say. Miniram is a good manifold for those rpm ranges. It will match well to the AFR's. HSR also should support those numbers

And yes a vortec head will need a vortec intake. Miniram i dont think is made for vortecs, but i know holley stealth ram is. I do believe it will support your hp goals too.

Thanks Orr89Rocz!