LT1 tips/tricks

[Z06killinSBF]

Not sure if this is where it goes or not but oh well.

I'm not a big Chevy guy but my dad has his friends 96 Z28 for a few months to do some general repair/upgrades. I am going to be helping him fix it up and we were looking at making it run a bit harder. Currently it has a fresh rebuilt Powerdyne 6lp blower, Crane RR's, BBK shorty headers, Stainless works catted Y-pipe, Flowmaster 3" cat-back. The tune is stock and so is the rest of the motor. I was thinking maybe throttle body, mass air and a tune. Who is a good tuner in DFW? Any ideas or suggestions on things to consider? It also has LT4 knock sensors in it.

[Z06killinSBF]

Ohh and pics of car for giggles....

https://static1.pt-content.com/images/noimg.gif
https://static1.pt-content.com/images/noimg.gif

[GeoffP]

Seeing as I seem to be one of a very few who run LT1's, I think I have a little input for you. I'm thinking a new MAF probably won't help enough to offset the expense depending on how much boost the Powerdyne is setup to produce. The stock MAF flows pretty well. You can always remove the flow director and port the MAF if you feel like it's not flowing enough. Some things I have seen done to compliment SC'd engines are to install at least a 52mm TB (58 may be overkill if the car has a stock cam). Check the rockers - going to 1.6 rockers (or even 1.7) is a good upgrade that yeilds a few ponies. LT4 valve springs, locks, and retainers is also a good upgrade. They're lightweight and are good to at least .525 lift (LT4 Hot cam lift spec).

This is something to consider since the car has a Powerdyne SC installed. I knew someone back in the mid-90's that had a Powerdyne SC on his car. He had problems with it not producing the advertised boost when it was setup to go 6 psi plus. (It was fine at around 4psi.) If I remember correctly, the problem was narrowed down to the belt slipping. I don't remember what all they tried to get it to stop, but I do remember he ended up switching to a Vortech unit shortly after because they couldn't get it to stop slipping. I'd be wary of increasing the boost beyond 4-6 psi, especially if the engine has many miles on it.

In my opinion, the LT1 is a great engine that has decent return for any investments you make to increase the power. As with any engine, to really get any serious power out of it, you've got to change the cam and heads.

I hope this helps some. I thought I'd throw in my .02 cents...

[Z06killinSBF]

Do you know how close a Vortech head unit is to fitting the Powerdyne bracket? I've heard about the belt issue and we've seen it too. This used to be my dad's car which he bought new and we did most of the mods to. Right now it is just a weekend car that RARELY gets driven. So far I've been looking at 52mm TB, 30ish pound injectors and a tune. The motor could use a rebuild (would be a built 383 if it came to that) but we weren't wanting to go that far.

[NoMoneyZ]

I would ditch the shorties and run long tubes with an off road Y. Swap that flowmaster out if its an 80 series muffler. Definitely get a dyno tune, if you can't afford it get a mail order one at least. On my stock car, an email tune, LT's, O/R y, and magnaflow netted me 30ish+ hp. Probably benefit your s/c car pretty well also.
I'd grab a 52mm t/b like stated above. Don't worry about the MAF.
Also, what kind of trans are you running? If its an auto I would recommend a high stall t/c and the most efficient cooler you can find, and gears depending on what ones are in it.

[GeoffP]

I agree with NoMoneyZ. LT headers will make a good difference on an SC engine (I'd forgotten about that). Get headers with 1-3/4" primaries to help it breath better with the SC. I highly suggest dumping the Flowmaster muffler too, regardless of what series it is. Even a cheap-o DynoMax 3" in/out muffler will flow better than the Flowmaster.

As far as a Vortech unit getting close to fitting in the Powerdyne bracket - it's just not going to happen. The guy I knew swapped the WHOLE thing out to a Vortech system with the aftercooler. It made a HUGE difference in his car.

Back in the day, Vigilante converters were the trick with LT1's. Just watch out for the issue that 4L60E's have with higher stall converters. The converter flash will cause the RPM's to jump way up between gears. It freaks the PCM out. There's a trick you can do to the tune to fix it, but I don't know what it is off the top of my head.

[Z06killinSBF]

It has the 6 speed thats been gone through and has a Centerforce Twin disk and light weight fly wheel.

If it was my car the exhaust would be off it and swapped like above but it's not. We are looking for simple stuff that isnt hard to do. The guy isnt really into racing it, just wants a little more umph, ya know.

[NoMoneyZ]

If he's not into racing and just wants a seat of the pants feeling, tell him to do 4.10 gears.

[GeoffP]

Definitely 4.10's go well with a T-56 (my 68 is a blast to drive!). I just reread your original post. I think with the combo it currently has I would suggest a gear change and a tune. If the SC is setup for 6psi, definitely look into anything you can do to keep the belt from slipping. I bet you're missing out on 10-25 HP due to a slipping SC belt. If it's setup for 4-4.5 psi, don't worry about the belt. It probably isn't slipping at 4 psi.

I've got to step up on my soap box for a minute. The LT1 gets such a bad wrap these days when it's actually a great engine that responds well to both conventional HP adders as well as modern HP adders. IMHO, a well built, well tuned LT1 runs very strong and is very reliable.

Again, just my .02 cents...