I have just bought my first vette. 1992 red coupe, 118000 mi, and it came with all the normal quirks (nothing that a test light and a shop manual cant fix though). My question for all of you experinced fellows out there is where should I start the process of getting my baby back to her more youthful self. Thanks to a semi truck full of gravel she's getting a new windshield and paint job (not the way I would have intended for her to get it, but atleast now its free). I dont want to do any major modifications, just enough to get her up to the 350-400 hp range. I purchased a Flowmaster cat-back exhust system, used optispark, water pump, and both shop manuals. I havent intalled anything yet. I also have plans for a K&N cold air intake, a port and polish of both the intake and heads, and whatever else will help get this old girl back up to speed. Any suggestions anyone has on where to start or where to get parts and machine work in Ca. would be great. Im not new to working on cars, just new to the Corvette LT1 motor. I have extensive knowledge of eletronics as I am an Avation Eletronics Technician, Im just not up to speed on all of the componets in the Corvette. The amount of them has overwhelmed me as I started reading through the manuals. Im just looking for a good starting point.

 

Used Opti-Spark? I hope it's not too used.

Things to add to your list:

Flush cooling system
Replace thermostat (160-degree works well)
Replace surge tank cap
Replace plugs and wires
Examine vacuum lines
Flush the transmission and cooler (Auto?)
Clean out from behind the radiator and condensor
O2 sensors may be close to death (?)

BTW, Welcome to the forum!

Blake

 

It would be nice if we could add an easy 50-100hp with minor bolt-ons....but we can't.
The advertising claims of 20-30hp increases with the purchase and installation of airfilters/airfoils/catbacks/thermostats/pulley sets/plug wires/etc/etc can be ignored.
For the power increases you are looking for, you WILL be spending significant money and doing some major wrenching/tuning on your engine.
The cheapest route for you would be nitrous, but that will still require paying someone who knows what they are doing to set it up (if not to install it in the first place).

There is no free lunch and no easy horsepower.
Let us know how it goes!

Larry
code5coupe

 

It is an automatic, sorry should have mentioned that. And im not scared of the wrenching and grease or the money Im gonna spend getting another 100 horse out of the motor.

 

Rocco is right. Especially in California There may be some CARB-approved shortes with hi-flow cats you can use there. The ported heads and intake will really help. Couple them with a hotcam, 1.6 roller rockers and a custom chip, and you might get the hp you are looking for. Oh, and don't forget the airfoil and parkbench spoiler (ha-ha).

 

You say you don't want to do any "major" modifications but if you are going to port and polish your heads, do it at a reputable shop experienced with LT1 heads. Also, install a HOT cam kit. They are reasonably priced.

With long tube headers and that Flowmaster you will easily get 350+ RWHP. If you have to use shorty headers you might still get there with good tuning.

 

When I say I dont want any major mods, I mean I dont want to redo the bottom end or stroke the motor. Pulling the intake and the heads are easier mods or at least from what I remember. I stroked and did everything a few years back on '79 Camero. I have looked and I cant find any long tube headers. Any suggestions? Also does anyone have any suggestions for a good machine shop for the LT1 in Central Valley Ca. or even in Ca. at all?

 

I may be of the minority here, but pushing 400 hp out of an LT1 with 118000 miles without doing any bottom end work seems a little counterproductive to me. If it's worth doing, it's worth doing right. Particularly if you are entertaining the nitrous suggestion and particularly if you plan on keeping and driving the car for some time.

Doesn't TPIS offer long tube headers for the LT1?

Congratulations though and have fun with it!

 

Good point! I missed that little detail.....

You might get the kind of power you are looking for out of your 118K mile engine...for a while.
If you want to get significantly more power out of your engine, you must start with a solid foundation. That means a bottom end that is stout; at least a fresh stock setup.
Aidoneus is right; you are, unfortunately, looking at those very major operations you wanted to avoid.

Larry
code5coupe

 

I have no intention of enteraining any thought of nitrous. To me using a bottle is cheating. If you want to be able to say you have 400 hp, than it should be the motor making the power, not some nitrous bottle. As far as the bottom end, it the car rus fine and from what Ive read these motors can handle the miles very well. I dont want to do that if I dont have too, and if I do Ill just sent the car to Ligenfelter for thier 1992 - 1996 Corvette LT1 & LT4 350 CID engine package, $ 9765.00. But I was hoipeing that I could do it for about half that myself. Maybe I crazy, but for 10k, I want more than 410/385. Anyone out there running a supercharger? IF so what are thier #'s?

 

If you are going to install a supercharger, you will have to rebuild your bottom end with forged components and lower your compression or you will blow your motor for sure. Or you will have to run your boost at really low levels which won't be worth the cost and effort of installing a supercharger.

I would just do a top end package. While you are in there you could change the rings on your pistons and maybe do a hone to freshen the bottom end up. But that will be even more money.

You should really spend your hard earned dollars on a head and cam package. Ligenfelter is really expensive but I am sure they do quality work. Why don't you check out:

www.eportworks.com

Lloyd Elliot will ship you a head/cam package that will make awesome power for a great price. LT1 Camaro guys love him.

Then contact Alvin at:

www.pcmforless.com

He will mail you a tune for your modifications. He is very familiar with Lloyd's packages. You will have to buy a piggyback adapter for your ECM to install the new chip. But they are reasonably priced and Alvin can help you out there.

Your biggest problem is getting long tube headers to pass California visual emmissions inspection. Exotic Muscle sell geat long tubes for our cars with all the emissions hook ups (O2 bungs etc..). But you won't pass a visual with them. You might have to settle with shorty headers (Hooker sells them I believe).

Just tell Lloyd and Alvin your are running shorties and see what they say. Once you get the heads, cam and chip mailed to you, find a good shop who can install them.

Trust me with a head/cam package and a good tune you will be making awesome power you can feel. I did the same thing to my 92 and I dynoed 371 HP to the wheels which is equivalent to about 430 HP at the flywheel.

BTW I went with Total Engine Airflow for my heads. You might want to check them out as well. Great LT1 heads at a good price. But if I had to do it all over again, I would go with Lloyd's heads and Alvin's tune. Just don't get to greedy for power and stick to Lloyd's Stage 1 or possibly his Stage 2 package. You want your car to be streetable, Stage 3 is more for drag racing.

 

Just because the car runs fine now with your existing engine doesn't mean it will continue to run fine once you boost the horsepower. As an easy example, it is definately possible you have a ridge now in the cylinders that isn't bothering anything as it forms where the pistons are currently stopping. Boosting the horsepower like you're talking about could start a piston slap. The percentage increase in horsepower you're talking about is going to add a lot of stress to the motor it's not currently seeing.

It also doesn't make sense to me to just hone the cylinders, at that point, in the grand scheme of things, you're not that far from doing the whole job. I just had my L98 bored out (and it was even within tolerances!) and it cost me about $500 to have it bored and decked. I'm going through the exact same thing you are with 93K on my motor and it purred like a kitten too, but I figure I'd rather build it right from the bottom up than pay for top end now and possibly pay for all the same work again later plus the bottom end, and as Murhpy's law would have it, you know something would fail at the most inconvenient time. My only regret is maybe I should have just stroked it to 383 while I had the block out, but frankly i'm a little terrified of my next credit card bill as it is.......

If you are planning to keep the car for a while, my advise again is to just bite the bullet and do the job right. What you think you will be satisfied with now in terms of power, will ultimately not be enough. It would be a great comfort if you decided to boost the power later knowing you already built the bottom end to withstand it. Just my $.02

 

OK guys, Ive done the reasearch aand taken all the comments into consideration. I have come to the conclusion that Im just gonna pull the motor and do the whole thing at once. I would rather invest more money now than invest more money later when it breaks. So we start from the bottom up, right? As, I stated before I dont want to stroke it, but what are the crank options? Do I go stock, or do I go aftermarket? What about pistions & rods?

 

That's a good question, I'd like to hear the answers too

Frankly, it didn't occur to me. I personally just had the crank checked and it was well within tolerances, so I just had it polished and reused my stock crank, but did I miss a good opportunity for more horsepower?

You're going to need new pistons if you bore the block. I don't have any suggestions for the LT1 though, I'm sure someone else will chime in.