So I'm planning on doing some modification on my corvette. I've got the l98 with an auto transmission. I have a rough idea of what I want to do, but I am completely and totally open to comments and constructive criticism here. Primarily I'm looking to boost my hp and torque numbers. I care less about top speed and more about acceleration. I want a car that will be fun to drive every day, yet easily pass some d-bag on the highway, or maybe take to a strip now and then.

My plan was to start with some long tube headers, then go for either a Corsa or SLP exhaust system. I know this will make my car sound great, but I won't be able to do this for a while, I work mostly in the summer and its still a lot of money for my budget. I'm also considering getting an SLP claw, but I don't know how well it will fit on my car (it's made for an lt1). Lastly I'm going for 3.73 gears. Now, question time

1) is it possible to put the headers on with the stock exhaust before swapping for a new system? I don't know if the installation involved welds or anything. If possible, I'd like to install them myself, but I don't know how that process works.

2) Corsa or SLP? (or other)

3) Is there anything I should know about installing the ring and pinion? Also, where to buy, should I be looking for a specific brand?

4) Are there any other modifications that you would suggest? Like I said I want higher hp and torque numbers, but I don't want to do anything huge like installing a supercharger or something. Keep in mind I have a tight-ish budget.

5) after I install these parts, do I need to do anything else, or will everything work like it should right away? I know I'm not adding hundreds of horsepower, but will the transmission be able to handle the extra power alright?

If you have any general input of any kind, please let me know. I want opinions.

Be gentle, I'm a noob. I've been starting a lot of threads lately because I'm trying to figure out what's best for my car, so I want to get everything straightened out now, so I don't have to worry about these questions later.

Thanks in advance to anyone who helps out

 

"Alex"

you performance questions have been asked hundreds of times. The basic performance threads are already in here. Keep searching you are on the right track

Click right there where it says "search"

 

I did search. I found almost the exact same thread for a C5 corvette, but I have no idea what does and doesn't apply to my car.

 

I recommend to learn about Corvette first before you start with performance or modifications. You are your Vette owner and if you dont know what applies to your car you must learn your Vette specs and how to do an advanced search.

Good luck

 

I've spent a while going through search results before posting this, and I took a few things out because I found the answer. I did use advanced search as well. I also just spent an extra 15 minutes or so going through searches on nothing more than "long tube headers" without finding much more than people mentioning them, as well as build threads.

I didn't write this all up because I'm lazy, I wrote it up because I can't find the answers.

 

Click advance search and limit your terms to this forum. You can even click on two forums (with the cntl-key). Don't include anything else.

Look for "horsepower", "headers", "mufflers", or "exhaust" in title topics. (Yes, do your search thru titles-only first.

You'll be reading for hours and hours and hours.

 

my opinion. I wouldn't waste my money modding out a L98 TPI. The TPI intake is **** period. until you change the intake your wasting your money on useless mods. the C4 corvette with a L98 with a TPI motor is slow no matter what you do to it.

 

I'll make it easy for you.

1. Yes it's possible but the single main cat and Y Pipe exhaust system on the L98 is real HP killer. Best bet is to buy the exhaust for a 92-96 LTX and fit it. Pretty minimal to switch the car over.

2. If your going buy an after market cat back Corsa is the way to go.

3. More to know about setting up gears than I can type in the time I have allotted right now.... Suffice to say it's not for a novice. Randys Ring and Pinion or DTS has all the parts you'll need.

4. Long tube headers, Corsa Exhaust is going be $1500ish... Parts for the gear swap is going to be 600ish.... how much more do you have to spend?
Will

 

I understand how to do an advance search, and I'm in the process. But the point of a lot of this thread was less fact based, I was looking for opinions. I don't need to know anything else about the exhaust, for example, I just want to know what people think sounds best on the car.

 

Yeah, I've heard that they aren't great from more than one person, but I haven't given it much thought (or any research). what intake would you recommend here?

Appreciated


Well I don't want to spend that much more. I'd say after the 2100 that would cost, I wouldn't really be willing to spend more than 900 extra. I dont want to put more money in this car than it's worth

 

Then fix what needs to be fixed. Fix UP what'll make the car look better...like paint, interior, engine appearance, weatherstripping, etc...

Anything, and I mean anything you spend on modifications will translate directly into loss. People are afraid of sellers who've modded their cars. Ask your dad.

Save for a newer, better car if you only want more power. You'll always be able to get more money back with that approach. Only fix up (mod) an existing car if you're willing to make it better than the money you spent on it....for your own personal edification. And, keep if for a long time.

 

I'm currently fixing everything that needs to be fixed. Everything that this thread talks about is happening only after I know the car is in good, healthy condition.

Once I said what you quoted, I kind of realized my fault in saying that. Like you said, I'll lose more money with mods period. What I really meant is that I don't want to put 4 grand into a car that I paid 4500 for. As far as mods go, I don't want to get very close to that number at all. Im planning on keeping this corvette a long time though, so after 3 years or so I'll most likely be open to spending more. Someday I'll buy a C5 or C6 but I'm getting ready to go to college next year, so saving up for a new car won't be the most possible thing in the world.

 

i get impatient with the search probably not good enough with it and dont have hours to spend to stumble across something. Dont worry about it.

65Z01 and Vader86 have a list of free mods that can help you can do on the cheap


If I were you in your case id leave the car bone stock drive it then move on when youre making more money.

But you wont. lol
SO.....

As said the intake and exhaust will help without digging in the engine.

You start modding a car start forgetting about having more in it than its worth. Its now a hot rod and you do it cause you enjoy it period. Youll NEVER get your mod money back most times.

You could do your own exhaust if you arent picky. Corvette systems are obscenely overpriced. Intake...look for a used LT1 intake thats been converted already can usually get one for under $500. A set of 1.6 roller tip rockers (dont need full roller) and some springs are a cheap upgrade.

I wouldnt put anything deeper than a 3.45 gear in youll go throught the powerband too quick. These are dead by 4000rpm unless you change intakes.

You can get a s-10 converter which will bump up the stall speed and fun factor some for cheap.

Just cut the air lid and leave the paper filter in it, throttle bodies special coils etc gain you nothing. TPIs are harder to get power out of as far as hp/$ but there are mods that DO work. You gotta commit to spending some money and turning a blind eye to it to go faster. THese are toys they dont have to make $ sense, long as you enjoy it thats all that matters.

 

of course not! leaving it stock would take away half the fun of this car, in my opinion. Sure its good now, its fast, lots of torque, etc, but it could be better. I want people to look at my car generally unimpressed, then pop the hood and wow them. That among other reasons.

For exhaust, I might just settle with stock pipes, a cat delete and a set of mufflers. It would be a lot cheaper and I'm sure I'm not missing out on all that much power by doing that.

Where do you find converted lt1 intakes? I google searched it and did a search on the for sale forum here, and didn't find one. Also how would this compare to en Edelbrock or USM intake?

I'll look into 3.45, but so far all I could find are 3.73, so I thought that was just the standard for this corvette.


Yeah I guess trying to be sensitive to money while doing this won't work, but I just don't want to spend a whole ton of money on this car. I'm hoping to install everything myself to save some money too, so that should help.

 

One thing you didn't mention is the current overall condition of the engine and drivetrain. How many miles are on the car? Does it use oil? What condition is the suspension in and how good are the brakes? What shape are the tires in?

Having extra HP and torque won't help if the car has weak shocks or the brakes are shot. One thing you have to understand is that the car in stock form is capable of speeds over 140 and with good suspension components it will handle very well.

You need to take those things into consideration before you dump hundreds into the engine. And if you increase HP and TQ, an old worn-out trans is going to object. So will piston rings, main and rod bearings if they are original and high mileage. Same with the differential and u-joints (any or all of the 6 of them ). It can cost as much to fix broken things as it will to do some add-on components to the engine.

The "wow" factor in an L98 in terms of appearance is not really easy to do unless you go with power adders like a supercharger or turbo. Headers are visible, but internal machine work or a cam is not. A clean engine compartment and some fresh paint will make the engine compartment look much better.

Headers will provide something like 15-30 HP depending on the entire exhaust system design but expect to pay $450 for Heddman Elites. While these headers can be installed at home, it's much easier if you have access to a hoist. The passenger side header has to install from underneath and the starter has to be removed. Then you have to connect the headers to the exhaust.

Do you have to have the car smog tested? If not, you can have true duals installed, but be aware that most shops will not remove cats if they are on the car. IF they get caught, it can be a 5-figure fine to them. A muffler shop would be the best bet for connecting the headers unless you are a decent welder and have access to pre-bent exhaust pipe.

A different gearset will provide the best bang for the buck. But auto trans cars got a Dana D36 diff while the manual cars got a Dana D44. The D44 is stronger and you can get a wide variety of ratios. Consider looking for a D44 and something like a 3.45 gearset.

 

It's got 148,000 miles, rarely uses oil but I have smelled it before. Suspension is good, holds the car pretty stiff but its still comfortable. I'm fixing the brakes shortly, I currently am not able to lock the tires. Front tires have about 35% tread, back have more like 80%. According to the last seller the engine was bored over 30, but I don't really know how to prove or disprove that. Other than that all stock. Tranny is good as well

I'm hoping to spread some of these mods out so that I can handle those imposing issues more easily than all at once. I know my engine is in pretty solid shape, but it is old, and I'm not expecting flawless results (although it would be nice )

The only appearance modification I'm considering are wheels and tinted windows. I would either like some newer zr1 wheels or something that's pretty solid and black.

I was looking at Hedmans, they seem nice and everyone on this forum seems to be a supporter. I'm either going with those or wasting more money on American Racing headers (unlikely)

In Missouri, the law is that if it's older than 1996, smog testing is not required. That's why I thought taking them off would be no problem. I haven't talked to a muffler shop about it but I would think that if I legally don't need them it shouldn't be a problem. If not, I'll just do it myself.

Tell me more about this. I really know nothing about differentials other than the fact that they are a factor in gear ratios. Where to buy, what kind of money I'm looking at, any effects it will have on driving, etc.

 

I'm running 3:73's in my 93 with a tranny shift kit. The only power mod I've made. Still get 16.4 mpg if I drive lightly. I don't think you can get a bigger bang for the buck. It's like driving my old 396/375 hp chevelle
cept a lot closer to the ground $1400. from Corvette Central or like my junkyard dog, $400.00 and my rebuild.

 

What kind of power are you after, i.e. street, strip, atuo-cross, etc?

My prior 35th Anni turned out 300chp and ran low 13s at 105mph with simple bolt-ons and stock 2.59 gears. "Simple" here means no real engine mods, though the A4 did get a TransGo shift kit and a 2,000rpmTC The exhaust used OEM headers but was hi-flow from there back.

As you likely know the real "trick" to building more HP/Torque is to increase air flow and then match it with the right amount of fuel flow. This can be done with a modified TPI setup w/o much (if any) drop in low end torque.

 

The D44 is physically stronger so it will be a help as you increase the engine power output. With the Corvette, the easiest way to swap to a D44 is to buy the entire "batwing" from a manual trans car. The two units are identical in terms of bolting in, but the D44 is beefier. Also, the D44 in the 87 manual trans cars uses a 3.07 ratio while the D36 is something like a 2.59. The 3.07 will provide a noticeable difference in acceleration over what's in your car now but will still provide a cruising RPM on the freeway at something like 1500 to 1700 RPM.

One thing about the 84-87 cars is that they have an internal drum-style parking brake. The wheels have a 36mm offset (you need to know this when going to aftermarket wheels like the ZR-1 style) and the distance between the hub flanges is different than the '88 and later rear. If you go to the D44, use one from an 85-87 car. Makes the swap much easier! You will also have to change the speedo gear in the trans for the different ratio.

As far as the exhaust and the cats, it's against federal law to remove a working cat from a car. State law in terms of emissions testing is something different. The feds can (and have) come down hard on a shop that removes working cats. One way you might get around this is to remove all of the exhaust, install the headers, remove the license plates and tow the car to a shop. Tell them you're building a track car and it won't be street driven. That way you can get true duals installed. Get some good mufflers like Borla's, Corsa's, Magnaflows or even DynoMax race mufflers. (Flowmasters are, IMHO, teh suck!!) and that's done. I have done this on my 87 and I have the DynoMax mufflers and true duals.

A .030 overbore is hard to prove unless the heads are off and you can measure the bore. But .030 is only a 5 cubic inch increase so it makes the motor 355 cubic inches. You can gain some power thru port-matching of the runners, and as mentioned some 1.6 ratio roller rockers. The stock valve covers have some tabs on the inside that have to be ground off for clearance. Look at Harland-Sharp rockers from Summit Racing.

 

There are a couple things you should specify before anyone can really help you out. 1)What is your goal for the car? What do you want the car to do? Drag-strip/Autox/Road Course/ weekend street car/ Daily driver or any combination. The type of modification you do to get the power you want and what sacrifices you will make differ with each application. 2) What is your budget, an exact number that you dont want to go over. To some people "cheap" or "budget" means $1,000, to others it is $10,000. 3) How often do you plan on working on it aka reliability? You say you can do your own work, which really helps because labor is going to cost as much, if not more, than parts if you take it to the shop. After you figure these things out, pick some keywords and use the advance search function, all this info is there for any application, you just have to learn what to search for.