I have a 1996 LT4 Corvette with a stock 350ci small block. I want to add horsepower and torque. I would like to get advice on the right way to do this. I do not want a drag or track car, I just want to give it a bit more power from the block. I drive the car I don't use it as a track or drag car. I understand getting new heads and a different camshaft is what a lot of people do, but with more power comes replacing other parts to sustain the power increase. I want to do this the smart way but i need some help. Also before I even start with adding power from the block I want to get the block, heads, valves, pistons, cylinders, etc checked out. I want to make sure nothing is worn or broken. I was looking into having the entire engine inspected, cleaned, and resurfaced if it needs to be resurfaced. I know it's a lot at once. Can you give me an estimated quote? I know it all depends on parts and what not. I just want to know a ballpark price i am looking to spend. Again I drive the car and want more power the SMART way. That's where you guys come in.

 

How much mileage do you have on your motor?

Since you already have a LT4, I would just do the following for a great street car set up.

-1 3/4" Headers
-Cam, GM Hot Cam or CC 503 cam
-Gears, 3.73 or 4.10
-Tune

 

it has 73,818mi on her.

I figured it would be good to get the engine cleaned and inspected/resurfaced... you think that's a good idea

 

can you explain to me what the 3.73 or 4.10 gear is?

 

Hi,

How much more power do you want? Do you want the car to be "more fun" to drive on the street or do you want to go "Z06 hunting"? How much work do you want to do? How much money do you want to spend? All questions that you should answer to help you make a decision.

73k miles is not too many miles to still have a reliable base to do some performance increases to. How long have you owned the car? In other words, did you put most or all of the 73k miles on it and know how it was driven and maintained? If "Yes", you can be more comfortable in doing modest hp increases without tearing the motor apart. If "No", and you have no idea about the car's history, then a 'pull and rebuild' may be in order if you want more than a modest increase in performance. Now, nothing says you HAVE to rebuild the engine, but a clean slate is the best way to go in this case. You will know what you have!

On the other hand, my 96 LT4 only had a 'tuning session' on a chassis dyno done and is a ball to drive on the street. Picked up about 30hp and 35lb/ft just from timing and fuel management changes to the stock computer. Enough to feel the results! To me, a 30hp to 50hp increase would make the car a bunch of fun to drive, be enough to make you feel you have gotten something for your money, and would not over-tax your current engine.

BTW, 3.73 or 4.10 gear is the rear end ratio. Generally, the lower number gives better acceleration than the stock (3.45) ratio at the expense of gas mileage and higher rpm while cruising.

At the risk of dragging out an old cliche, "Speed cost money. How fast do you want to go?"

Good luck and have fun.

walt z.

 

walt the car has been through 4 previous owners.. the most recent owner i know personally and has had it for 2yrs now.. i just bought it from him. The car is in great shape.. runs smooth and powerful. So i would like to know what i have and get it inspected. So i'm more confident in the build ya know.. I don't think i want to go Z06 Hunting lol just a fun street car with more power is good for me.

How much would i be looking at for a pull of the engine and inspection/cleaning? Now how much i'm willing to spend... idk cuz idk how much i'm would be looking at spending for what i want..


But just a tune of the vehicle will gain power and tq with no mods? That's really nice.

Also with a job like this i wouldn't trust any ordinary mechanic shop.

 

Hi,

Since it looks like you'll be having someone else doing the work, you probably need to be asking about recommended Corvette shops in your area. I'm in Texas, so I can't help you there and I (and my friends) have usually done my own work, so I also can't give you a money amount.

But asking here is sure to get you some responses.

The factory 'tunes' the cars with mileage, emissions, 87 or 91 octane fuel usage in mind. An experienced tuner and a chassis dyno can change the tune to take advantage of 93 octane (Premium) fuel and any other changes you have done (headers, etc), so more timing quicker, and a better fuel curve will unlock a certain amount of power. Btw, my car still passes state inspection with no problem although my convertor is probably working harder!!
Whether or not you want to still be able to stay 'legal' will also determine the amount of work you can do.

Good luck.

walt

 

My set up is hot cam, headers, honker intake, porting of heads/intake by Lloyd, along with a few other little things here and there. I get over 370hp/350torque at the rear wheels. Hot cam lets you get decent highway mileage for DD. I forgot to tell you about the bottom end; it is stock with 135K miles on it. Be sure to get the upgrade timing chain from GM if you change your camshaft.

 

Well, imho, it would be pointless to tear it down to the point of being able to inspect all the internals. If you're going to pull it apart that far, there's no sense in putting nearly 20-year old parts back in it, even if they do "pass inspection."

If it were me, if I pulled it apart, a new crank, rods, piston, rings, cam, etc. would all be getting put on. And I'd probably go with a mild stroke like a 383, possibly new heads and of course headers.

If you don't go too overboard with the specs, you can still make quite a bit more power, but still have good "street manners"... when they're needed

 

Another option is to just get the ZZ4 short block (the LT4 is a ZZ4 bottom end) and have your heads reworked as I said by Lloyd Elliot. Put it all together with the cam of your choice but don't go overboard and get too big of a cam if you want low end torque and decent mileage. Do not machine your flywheel if you can help it. Just 'dust' it off and reuse. Good luck finding a knowledgeable tuner. They are hard to find for that particular OBD2 as it was only used for a couple of years and most tuners don't touch C4's because so many are not in very good condition.

 

one thing to watch for is some unscrupulous mechanics see dollar signs when a vette come into there shop. What I would do is get a compression guage and do a compression test on your motor yourself. that will give you a fair idea what the condition of the rings and valves are. If you have good even compression in every cylinder with that amount of miles and being its an lt4 id leave the bottom end alone. You will also have a chance to inspect the cylinders for big problems when you pull your heads. As to what to use to make power ill leave that to the guys here that know. My knowledge is more pre lt1 era small blocks. But one thing to make sure of. Don't go and buy a bunch of different parts because you got a deal on them. Make sure what you use for heads, cam, headers, intake, injectors ect are proven to work well together. My advice is you look at a few of the recommended shops that sell packages. Your probably looking at around 2500-3000 bucks for your heads to be done, cam, headers and intake. That doesn't include tear down and instillation if your not doing it yourself and like any other take it to the mechanic deal you can about bet on labor coming close to match the price of parts. You will also need a tune if you are doing anything but adding headers and a exhaust. Even with just header a tune is a good idea. I think the first thing id do before touching anything is buy a compression guage and start looking for a nearby shop that can tune your car.

 

Then stroke the motor dont get talked into throwing a big cam or overported heads at it youll be real real happy in the long run

sounds like youre driving habits are more conservative imo this would be my choice.

 

The engine survives on clearances and they make bearings to maintain clearances. Even if a crank needs to be cut down, it is just fine for street use but based on the fact that there's nothing wrong with the engine right now, he probably won't have to do anything to it.

The sense in it would be the cost involved with replacing all of those components versus going with his original plan.

 

I agree that if the engine runs fine and only has the mileage that's indicated, there probably is nothing wrong...and I wouldn't be tearing it apart just to inspect it. Compression test, leak-down test, and look in the oil for evidence of problems, and if all is good, leave it alone.

But, he said he wants to have it pulled apart and inspected. If he were doing the work himself, I would say go for it, but since he said he's wanting to have a shop do it, a lot of the cost will be in labor. Why pay all that labor just to put back old parts, even if they spec out okay? If you're paying all that anyway, it's not too much more to make it a mild stroker.

 

That's great to know! I've blown up my LT1 and wanted a factory option to replace it.

 

I hear what your saying.. don't have to budget to basically build a new engine.

 

well that's not good.. i'm moving to Colorado this year.. i'll have to look around for a tuner. As for flywheels i've seen a lot of people putting in aluminum flywheels

 

thanks Lloyd, great advice