I have an LS1 1998 C5 with 195K miles and I'm thinking about swapping the engine in about 6 months or so. Being a n00b at engine work (OK car performance in general), I've been doing lots of research and set the following goals:

1) Would like to reuse a lot of the performance parts I've already invested in which include:
- LG street headers
- FAST 92mm intake
- Nick Williams 90mm TB

2) I would like to end up somewhere in the 500RWHP range

3) Street legal (haven't been to the track in a long time)

4) I want to swap the engine myself for the sense of accomplishing something.

5) Has to be able to pass TX state emissions.

Based on research, I am leaning torwards an LS6 stroker with forged components and a supercharger. A&A seems like a great fit in terms of what they have to offer.

My questions are:
1) Am I headed in the right direction to acheive my goals?
2) I have a stock automatic transmission, up to what HP is it rated?
2a) Will I have to replace the transmission or can it be built up to take this much power?
3) Can the 98 C5 computer be tuned to control a stroker?
4) Will the stock rear end take this much HP and if not, what are my options?
5) Are my mods listed above appropriate for this type of motor build?


Thanks for any help you all can offer.

Mowpow

 

You don't need another motor or a stroker or anything like that. Just having a supercharger will get you in the 500+ rwhp range all day long. I'm at 512rwhp @ 8.8psi with meth with 124k miles on the original LS1 longblock(and clutch!).

 

This is defintly the truth but with nearly 200K on the engine I personally opt for the rebuild.

Now with the goals you are setting I dont think you need more then a forged rods and piston setup as the stock crank will take 700rwhp all day long. There is really no need for a stroker with those goals, you can make over 600 rwhp on stock displacement with no problems. There are multiple manufacturers that can provide you with oversized pistons and personally I wouldnt hone the cylinders to anything over 3.905. Wiesco and Callies would be my first choice for good parts at a reasonable price.

To answer some of your questions.

Yes you are headed in the right direction, a supercharged LS1 in ANY form will make 500hp without effort.

Your stock tranny will NOT survive at that power level but it can be built to support way more. I would contact RPM transmissions.

The stock rear will most likely be fine as long as your not at the drag strip on really sticky tires. If so i would consider upgrading or your on borrowed time. RPM transmission can help you with this upgrade as well.

The mods you currently have would compliment a supercharged engine just fine.

Good Luck!

 

Sell it and buy one that it's already done. You'll save a lot of money.

 

the 500rwhp is easy on just about any combo of the ls1
the A4 will not live at 500 very long
the rear end will stand up if you do not abuse it or run stickies
you current mods work well with a centri or turbo
the stock PCM 98 pcm is somewhat of an issue but can be programed to deal with it
Texas emmisions what the heck is that

as to the engine I was in the same boat with a 80k mile short block and decided to install the blower in it and see how long it lasted that was 35k miles ago and still no problems with the short. The 200k mile short block is not worth much and the replacment engine does not require a core (in most cases). I also do not recomend rebuilding the 98 block (issues with thinner cylinder walls)

I would have a leak down test done and a compression test and if the engine came back as ok I would just have the sc installed and tuned (good tuner do not cheap out and make sure that the tuner is good) and run it, if and when you have a problem with the short i would go to a ls3 416 which will put down 500rwhp without the blower (just start saving up $ for it) IMO the stock short could make it to 250k without issue and you will not save much money by swapping the engine at this time

 

 

Gonna have to disagree with you here.

Buying a set of forged rods and pistons, having the machine shop hone the cylinder walls to 3.903 or .905 and balancing/assembling the bottom end will be under 2K total including machine work. Buy a set of TSP or Patriot heads and call it a day. Lifters, timing set, oil pump.... all said and done for $3500 or less.

Machine work is very reasonable, atleast around here and its QUALITY work.

Last bill I saw was for a friend of mine, This was for a factory new LQ9 Block.

Block washed
decked
rotating assembly balanced
Crank milled for a KEY, not a pin
All bearing clearances set
Crank installed with studs and main girdle
$600

And if you do all your assembly yourself, like alot of us do. The price goes DOWN.

 

Given the cars high mileage and other cost associated with building a 500 + RWHP vette, I still think it's cheaper to buy than build.

Motor parts around $4K if nothing is wrong with anything. Add a transmission, TQ converter and upgraded differential and you're looking at $3K - $5K. Now go buy a blower $5K. Add a tune $650.

That adds up to $12K - $15K you doing most of the work.

Sell the current car for $10K and buy one already done for the other $15K you're going spend.

That's how I see it, unless you're a gluton for punishment.

It doesn't take long to spend $45K building up one of these vettes.

 

1) 383 will easily get you to 500RWHP with boost. A friend had a hefty 383 built and N/A he was pushing 504 at the tires.
2) Not 100% sure but NOT 500rwhp
2a) I am sure it can be built up but RPM probably has the best 'drop in' A4 out there.
3) Yes, although the tuner may suggest a swap (at least my tuner did with my friends '98 TA).
4) As long as you are not doing any big launches at the track you should be fine, my stock rear is holding 566/594 currently (rwhp).
5) Your mods definitely won't hurt the cars performance

Good luck!!!

 

Great ideas being shared here, I really appreciate all the help.

I have thought about selling the 98 and getting something already built to hit 500rwhp.

I bought this 98 pretty cheap ($7500) knowing that it would be my project car and something to build up so I could learn and have something to be proud of. Given this situation, I am definitely going to keep the 98 as I've done a lot of geeky electronic stuff already (custom alarm, PA system, some LED interior work, etc) and I'm already kind of attached to her hehe.

Given I was not the owner during the first 194,000 miles, my first thought was to replace the motor. However, I never thought of just slapping on an SC, tuning it (or replacing the PCM), and replacing the transmission with a built up one. If it blows, oh well, I'll replace the motor as planned. The one thing that does kinda scare me about this approach is whether the motor failing would damage the SC. It would really suck if I blew the motor and jacked up the SC at the same time. Could this happen? Also, what would be a safe amount of boost to run with non-forged components?

Thanks again for all the help.
Mowpow

 

Your odds of hurting the supercharger when the engine lets go is VERY VERY VERY slim. Odds are your just going to crack a piston.

 

being that it is a 98 (thinner cylinder walls) I would be looking for a diffrent block to rebuild anyway (for a FI application).

 

I'm running 11 - 12 psi on a stock bottom end but a safer number would be 9 psi with a centri you will be into 500rwhp easy as long as the bottom end does not have serious issues already (just check it out with a leakdown test) you do have good oil psi right?

IMO no reall downside to this approach just take your time and get it done corectly and if you are doing it yourself when it comes time to rebuild you will have had pratice.

 

I've got a 98 as well, and have had it since it was new. I too am kinda attatched to mine.

Good luck with the project, sounds like you have a pretty good idea what you are doing!! I still run my car off the stock PCM, and make a bunch more power then you're looking for, so you should be fine there.


JB

 

I also have a 1998 with a LS1 347 Forged (Most parts listed in sig) with a ProCharger an A4 and a 3.42 rear making: 701 RWHP and 582 RWTQ @ 14.4 PSI of Boost! - effortlessly, soon to be in the 9's ()and still getting 28 MPG on the highway!

It can be easily controlled by the '98 PCM, the best thing to do is go 2 BAR SD tune if you go FI - MAF can be re-installed when it is time for smog

Mine passes California smog, blows clean due to proper tuning for SMOG TIME (I have two tunes one for smog time, this help, that is having HP Tuners inorder to make the adjustment)

Thanks,Matt

 

Nice numbers, looks like you've done some nice work with the LS1 (read over your sig)! Did you have your A4 rebuilt or did you swap it out? The A4 in my 98 was recently replaced so it's pretty new (probably 20K miles on it). Thinking about getting it rebuilt but I definitely don't want to ship it!

 

Yeah! I finally had to get the A4 rebuilt after 90,000 miles! Level V build - works great too!

Just get a tuner who knows how to tune the A4's and you will be plenty pleased with the way it works

Thanks,Matt

 

matt are you still running the 98 block casting?

 

Yes! I am.

My engine builder and I went over every detail and goal and it is built to make what I have and more -

NO expense was spared, block is in perfect condition, and as we know how important heads are I spared no expense on them either, this motor makes this power effortlessly, from the Heads to the cam to the rods and crank etc.

Usually people say "NOT" to build the '97-'98's but that is if you are gonna punch one out to the max and stroke it, then a later block is better or actually the LS6's (as well as the '04 LS1 which has the same block # as the LS6) metal is far superior and that would be the one to build out of them all

That's why mine is a 347 from the stock 346 CID, we did not go crazy on opening up the walls/sleeves and kept it well within acceptable limits of the '98 LS1 block

Thanks,Matt

 

I also want all to remember if you have a tuner that "KNOWS" what he is doing on a A4 it can withstand 600+ RWHP for a long time!

My tranny lasted 90,000 miles w/out a tranny cooler and if I had one in place at the time it would still be going

Best bet is to:
1. Find tuner who knows what they are doing on a A4
2. Get a "Quality" transmission cooler
3. Fully flush the system and change filter twice
4. Get a Stall Converter 2800-3200 (YANK Converter, IMHO )
5. A complete set of new solenoids for under the pan (Very cheap, less than $100)

As far as ones saying the rear wont hold up, REMEMBER it's an A4, they are way easier on the rears than manuals when they launch, mine comes out of the hole very smooth and really starts to pour on the power!

Now as far as MOWPOW is concerned his best interest is going to be to install a new one from RPM Transmissions - Level V @ least (Mine now is at the Level V),

This is a must since yours has so many more miles than normal on it, you wont regret it - Don't have just "ANY" transmission shop do a rebuild, if that is what you decide, make sure they have much experience with the Vette's transmission

Thanks,Matt