I have a 1996 Trans am m6 lt1 (89,xxx miles) and I'm wanting to build the engine. I'm a complete newbie to cars mechanically speaking ( only know the very basics of cars mechanically) , but that can be changed, right? I bought this trans am on the 18th of July this year, and have yet to really "test it" but Im almost certain it already has mods. It does have some killer exhaust, and I think 4:11 gears with close ratios. I'm not sure if the stock ones do this, but the rear end does whine a little and the car shakes a little at idle.It also does "rack off" And is believed to formerly run nitrous. At idle, its solid at 1k rpms.I'm not sure about clutches, but its pretty forgiving and not hardcore.As for the opti, I think it's fine, but obviously not sure whether its been recently replaced. The engine is very responsive and operates finely at 4k. Transmission shifts extremely smooth.

Enough about the mysteries of the car. Im not looking for a crazy amount of horsepower ratings (maybe 450)(Id like a torquy setup if possible) , but I am indeed looking for a very street friendly and reliable build (maybe even daily do able) . Budget isnt really important, but Id like to not break the bank.Id even welcome an entirely new engine swap (gets rid of the opti too ) I know this may be stupid to say, but I also want it to sound awesome too (like it does now).Im most likely not going to take it to the drag strip very often. I would like for it to be able to take forced induction (turbo(s)) if I decide to do so (if possible).


If you need more info, ask away.

 

Congrats on your first f body and welcome to the forum. There is a TON of information on this forum as well as others like ltxtech.com and ls1lt1.com. You will need thick skin for this one I will warn you now, but there are some very knowledgeable people on here that can help you reach your goals.

First thing is first, understand that forums offer an unbiased opinion on parts, since nobody here profits from your decisions and purchases. Vendors, like comp cams, summit, jegs, etc all profit on how you spend your money so before you open your wallet on any parts, do a search or ask questions. The LTx platform is very unknown to a lot of shops, it is completely different than an LSx or a small block Chevy. Nothing but the lifters interchanges with an LS, and although the rotating assemblies are the same as any 1 piece rear main seal sbc, the reverse flow cooling system allows higher compression on pump gas than an sbc, so a traditional small block guy might tell you 10:1 is as high as you can go on 93 octane, but you can do 12:1 no problem in an LTx. Again, before opening your wallet, run it by the forums.

For figuring out where you are now for mods and power, take it to a track. Your trap speed tells your horsepower. If you trap 100-103, you are stock. If at 80mph you are at 2000rpm, you have stock 3.42 gears.

For adding power, start with the basics. Long tube headers, cold air intake, short throw shifter, skip shift eliminator, and a mail order tune. If you want 400+rwhp, you need heads and cam. Ported stock heads can get you there, Advanced Inductions or Lloyd Elliot are 2 very good porters that are well documented and widely used. An off the shelf cam and as cast aftermarket heads like Trickflows will not make as much power as ported stock heads.

The limits of the f body stock are the self aligning rockers and valve springs start to get dodgy around 6300rpm. This is fixed with non self aligning 1.6 ratio full roller rockers like comp pro mags, scorpions, crane golds, crowers, etc, some 7/16 ARP rocker studs, hardened pushrods, guide plates, and better valve springs.

The stock rod bolts stretch and fail around 6500rpm. This is fixed with resizing the stock rods for ARP rod bolts, but requires tearing down the bottom end.

The 7.625" 10 bolt rear end will fail at stock power levels and sticky tires if you dump the clutch. This is fixed by either upgrading to a ford 9", GM 12 bolt or strange S60 but costs $1500-3000. Or you can be easy on your launches at the track. The rear end is pretty much made of glass and you have to be easy on it until you replace it. A girdle, gears, welding the tubes, etc is just a bandaid, it won't hold up to 400+rwhp and sticky tires at all.

I recommend spending a lot of time reading other people's build threads, and finding one you like, and the copying it. Don't just order random parts from a catalog or you will be very disappointed.

Terms to avoid: if you hear someone recommend any of the following, politely disregard it completely.

Edelbrock - while edelbrock makes great parts for sbcs and bbcs, they have NOTHING good for the LTx. Absolute wastes or money.

Hypertech - overpriced garbage tuners that are "one size fits all" and is worthless for anything but adjusting your speedo after getting new gears. Get a mail order custom tune from pcmless, madz28, trifecta, moehorepower, Ed wright, etc, for $200, or a full dyno tune for $400-600.

Eagle CAST crank - eagle and scat are Chinese brands, and while their forged cranks are good, their cast cranks fail much faster than a stock gm crank. Absolutely do not install a Chinese cast crank or it will break and destroy your whole motor.

LS anything - as said before, NOTHING interchanges, not the heads, not the intake, not the rockers, nothing but the lifters.

10:1 compression ratio - stock is 10.4:1, the lt4 was 10.8:1 stock. You can do 12:1 on 93 with the LTx.

 

Thanks for all of the information.

 

Dont forget about the thick skin thing on here.

It would also help to create a signature with all of your mods to help people know what you have done and need to do.

There are no close ratio 4.11s, you mean close ratio gearbox, that doesnt apply to rear ends.

You can either build a motor for forced induction, or you can build a motor for naturally aspirated operation. Forced induction requires lower compression. You cant build a 12:1 NA motor and then strap a turbo to it and expect it to be hunky dory. You can build a 9:1 compression turbo motor and run it NA, but it wont run fast until you give it boost.

I dont know what you mean by "rack off".

Rear end whining probably means your rear end is about to blow. Like I said, the 10 bolt is made of glass.

Shaking at idle could mean it needs a tune up. Have you taken it to 6000rpm yet? Do it and see if there are any studders. Dont do it without load, do it while accelerating. Do not rev the motor to 6000 in neutral.

Take it to the track. Enjoy the car. Figure out where you are now with mods, then start building. Does it have headers on it now? Does the muffler say a brand on it?

Post some pictures of the engine bay and the whole car!

 

If you just want around 450 hp a head and cam swap with Bolton's would be a cheaper/better way to get there than to run boost on a stock engine. If you want boost and want it to be reliable be ready to spend some $ ive got almost 5k in my engine alone. And i still need injectors ported intake and a throttle body. The price of boost goes way past the initial cost of the turbo or supercharger just some food for thought.

 

I was talking 450 on engine alone, but yeah, thanks.

 

Yeah, I meant a close ratio gearbox, sorry for the mixup.

I cant explain "racking off", but exhaust has a certain sound at that rpm range, It might just be called popping, but not sure. It doesn't sound like there is something wrong or anything.

No, I haven't taken it that far yet. I've only driven it 5 times so far.Ill be sure to do that.

I'm almost certain it has headers on it.The exhaust tips say "slp" on them, but not sure about the rest of the exhaust system.

I will take pictures eventually.

 

You don't have a "close ratio gearbox", you have the same t56 as the rest of us. Pics will tell a lot of the engine bay.

 

I tried to post pictures. Its been like a week since I tried to post them.

 

Actually it is a *close ratio* box but we don't think of it that way because the wide ratio box was 93 only and is less desirable due to it being weaker.

 

Close ratio stock. No closer than everyone else on here. Not considered a mod, or worth highlighting.