90 IROC Conv

I've got a 1990 Convertible IROC, it is completely STOCK!! I've had it a lil over a year now just enjoying it and driving it and now I've come to realize that I want something faster. I don't necessarily want to go out and buy another car, I want to build this car, its got a 305TPI, A4, Flowmaster muffler, it came with the Group 3 purchase option with ALL the fixings, Power Windows, Power Locks, Power Mirrors, you know what I mean.

I do realize that these cars were extremely rare, that there were only around 1200 convertible IROC's built that year since it was only a half production year for the IROC's but with 120,000 miles on the odometer, I'm begining to wonder if a lil resto wouldn't hurt it , don't get me wrong there really is nothing wrong with the car, its been repainted and the top replaced recently, new trans., new radiator, alternator, water pump, TPS, new plugs and wires recently, oil and filter changed every 3000miles religiously, new brakes and rotors. Really the only thing I can think of that is wrong with it right now is that it is beginning to smoke quite a bit when I start the engine which tells me that the valve seals are leaking.

Really all I'm looking for is suggestions, I do want to stick with fuel injection but either way the 305 and A4 is coming out and I want to replace it with either a 350TPI, LT1, or LS1, any of the engines I choose are going to be built before I put them into my car. I'm not worried about money so don't even bring that up all I'm looking for is the best bang for my buck and I'm going to be doing a trans conversion also, if I do put a 350TPI I want to put in a BorgWarner World Class T-5 in it(I heard that the World Class was the best T-5 you could buy, if not please tell me which one is), or if I go LT1 or LS1 I want to put in a T-56. Please feel free to leave suggestions, I am leaning more towards an LS1 but I'm still not sure.

Thanks a lot for viewing and please leave me somthing.

Third Gens

Drkhrse89

You can mate up a T56 with a 350TPI it is pretty much a direct bolt in. There will be some modifications needed but nothing so bad that you cannot do yourself. I would say go for the LS1 if money is not an issue. Myself money is an issue so that is why I am building a 350rwhp motor for around $1500 and not just buying one. I have a friend that has put an LT1 in his 3rd gen and that thing runs like crazy. I also have a friend that has a 355 6 speed and is running in the 12's. The LS1 will be pretty tricky to get in there since not many people have done it yet so you will have to think of some original stuff but the LT1 has been done by quite a few so there should be plenty of info on it. Good luck I probably wasnt much help at all.

TheGreatJ

Even if you do go with a TPI setup I would really suggest runnin a T-56 behind it. It's really much stronger than even the WC T-5's, which aren't known to last long behind well-built 350's anyway.

If I were in your shoes, I would probably go buy a 350HO crate motor, drop a super- or mini-ram on it (so you don't have to rewire the whole damn car), strap a 6-speed to the back of it, and run 3.73's in the rear. That or buy a used block and build a 383.

Keep in mind that the vert's are a lot more flexible than the hardtop cars, so if you get something with pretty good power you'll HAVE to get subframe connectors to keep from twisting the unibody to peices.

90 IROC Conv

Ok, this raises another question, every place I go and look at SFC's always says in bold print "NOT FOR CONVERTIBLES" I've looked at Hotchkis, BMR, and a couple other places. Why is that they don't work on convertibles??

So if I'm going to build any of these motors, I should go with a T-56??

n2ceptor

If Year One can put a LS1 in a 1969 Camaro Convertible (PHR Oct 2002) you should be able to do it too. Plus it would look KICK @ss ..... And the car came with an auto..I would stay with it..That would be one less thing to worry about....JMO

I'll look and see if I can find a SFC site....I know the roll bars are diff....

93Z Will

87ROC

I beleive both the LT1 and LS1 have the advantage of cooler running heads due to reverse flow which allows higher copression ratios. And they come with a better fuel injection system. And both have better flowing heads. The LS1 has the biggest advantage on the heads. But if money is no object there are much more selections for the L98 as far as heads go in the aftermarket. And those heads can way outflow even the LS1s. With some highflowing heads and about 9.5 to 1 compression ratio and a decent roller cam say from comp cams and after market intake pieces for the TPI setup the L98 will be a real performer and be much easier to swap.

I also think the T56 will be the best bet even for the L98.

AutoRoc

Here's what I SHOULD do...haha

Save up a little pocket change and buy a brand new 422 LS1 engine from MTI...Something with fully ported LS6 or C5R heads(probably LS6)...a trick intake possibly plumbed for a direct port nitrous system in case i get bored with the new power....:metal That would be mated to a TH400 transmission that is build as tough as possible, right after that would be a Gear Vendors Overdrive unit, a new Denny's Driveshaft built for the abuse, a new 9" rear axle with a nice posi...

Sticky tires...cough

or just a stock LS1 with some stage 2 heads from GTP with a matching camshaft...that would rock in itself

aklim

What about Alston Racing at http://www.alstonracing.com