I am purchasing a '98 C5 and need some advice. I have spent a good bit of time searching around the site and am trying to figure out the best modification path. What mods will yield 350rwhp and what will they cost (approx.)? What mods will get the car to the 400rwhp and what will they cost (approx.)? Any suggestions besides forced induction/nitrous to get above this HP level that will retain relialbility?

What are the vettes trap speeds/ ET's at those hp levels (1/4 mile)?

I want a car that is reliable as this is going to be my daily driver (my 300zxTT continues to give me issues and is very hard to work on).

Another way to answer would be to simply list your mods/HP/ET/Trap Speeds.

Thanks for your time guys.

-Aubrey
'93 300zxTT (Selling)
'98 C5 (Purchasing)

 

You can get to 330 rwhp or so without getting too carried away with your wallet. Add LT headers with hi-flow cats and x-pipe ($1,300) + LS6 intake manifold ($400) + air intake (Blackwing or Stinger for $200) + tuning ($500) = $2,400.

The first additional 20-30 rwhp is simple and relatively inexpensive. It's the next 30-60 that get *very* expensive.

My setup last year: ( Car is a Y2K FRC M6 )

Mods:LS6 intake manifold + Donaldson Blackwing + Magnaflow X-Pipe.

Dyno: (Mustang @ DSW) = 302.5

1/4 Mile: (With stock run flats and gentle shifting) 13.3 @ 110.5 MPH.

Current setup: Same mods as last season with the addition of Dynatech Headers.
Dyno: N/A
1/4 Mile: 12.8 @ 114 (same run-flats)

I felt 12.8 @ 114 with a mostly stock setup was doing pretty well, but, wasn't as fast as I wanted to go. This is the point where you really need to figure out what you want to do with the car, how much you are willing to spend, what if any stock or 'daily-driver' characteristics you are willing to sacrifice.

Three main go-fast options:
1) Heads + Cam (H/C)
2) Forced Induction (FI)
3) Bigger motor (383, 427, whatever) ( Stock = 346 CI ).

For me I didn't want to mess with a bigger motor or N20 and the H/C setups I have seen don't even come close to driving like a stock car so I was really only left with FI.

Twin Turbos or a Super Charger: That is the question ..

TT's = $12-15K by the time you get them installed, tuned, etc ...
SuperChargers = $6-10K. I didn't want to replace my hood ( MagnaCharger ) or drill my oil pan (Vortech) so I was left with the ATI ProCharger.

After much research I decided on the SIC ATI D1SC from ECS.

My advise is to figure out roughly how fast you want to go and what type of driving you plan on doing (road race or drag race or neither) before going down the mod path. Talk to some local Vette guys with H/C, stroker, and FI cars .. Go for rides, listen to their cars, etc, all of this will help you decide what is best for you.

Cheers and Good Luck,

Mark

 

(i'm glad they did not get rid of this little guy)

 

Mark,

Thankyou so much for the detailed reply. You asked me "how fast do you want to go" and i know what will make me content: Trap speeds of 114-116mph on pump gas... ET comes down to driver. I would really like to see trap speeds of 120mph but i dont know if that is possible while remaining reliability with the LS1 (Im sure its possible with the LS6).

I do have a few more questions for you:

1. What is the difference between your motor (Y2K) and mine ('98) in regards to how they respond to modifications?

2. How much power do you think you made with the addition of the long tubes?

3. How much power is typically needed for trap speeds of 114-116mph in the C5? How about 120mph?

4. How often do you drive your car since the addition of the charger? How reliable has it been?

5. What vendors sites do you recommend i visit for good customer service, good pricing, and honosty?

Thankyou so much for your reply!

-Aubrey

 

I didn't bother with a dyno after I added headers (about a month ago) as it was shortly after I added the headers that I decided to add a blower (which will require a full dyno tune).

1. There aren't any differences between a 98 and a Y2K as far as engine internals go that I am aware of.

2. Considering that I ran 110 MPH in the 1/4 at 302 rwhp (remember these are conservative dyno numbers) my guess is that I'm making around 330 rwhp with the addition of LT headers.

3. Figure 340-355 rwhp are needed to run 114-116. Figure 400-420 rwhp to run 120 MPH. The difference between a car than runs 114 and 120 MPH are night and day. Keep this in mind..

4. My car is still at the shop getting the blower installed. I should have it back by Monday.

5. This question is difficult to answer as CF has a number of *very* good supporting vendors. Your decision would probably be based primarily on location. I have ordered from ECS, Corvette Garage, LAPD, ThunderRacing, and a number of others and have yet to have a problem.

Mark

 

mdhmi outlined some good ones.

Is your C5 an auto or manual...?

For the A4's, one of the best and popular
routes is a gear change, the adding of
a TQ converter, and a good tune.

I'm running 3.42's, a Yank SY3500 and
probably one of the best mods you'll ever
do is to rid yourself of the run-flats.

Gears can go 3.73's, 3.90's, and 4.10's.
Each offer pros and cons depending on
highway miles to be travelled vs. track
time etc.

 

Mark, Thanks again for the reply. I live in Atlanta so if there is any particular place you guys recommend for parts/tuning please let me know. A hair over 400whp yeilds traps of 120mph!? Thats great. Is that common with most C5 owners?


PureRock105,
6 speed.

I do have two more questions:

At what hp level does the stock clutch start to slip?
How much power is the stock Differential good for?

Thanks again guys

-Aubrey

 

A stock 02-04 C5 coupe with 3.15s will run in the 13.20-13.30 range. Of course, depending on driver and altitude.

Add a good air intake, cooler t-stat, headers, high-flow cats and x-pipe. The mid-high 12's are possible. The 02-04s have the LS6 intake on the LS1 motor already.

A manual car/Z06 has the better advantage as they can launch the car at a higher RPM. Therefore getting better 60' times and 1/4 mile times.

I need to take my car to the track but with the header mod I am hoping for a 12.70-13.00.

 

Pettrix, Mark was saying that with those mods (LS6 intake, air intake, headers, x pipe, cat back, and tuning) that trap speeds of around 114mph are expected. With trap speeds that high you should definitely see low 12 to mid 12's. Are these not the trap speeds you think you will see? Do you live in higher elevation area?

 

The track is about 1600 feet. I guess only time will tell. Once I get the car to the track I am hoping for high 12's. If I can do better, great, but I would rather error on the conservative side.

 

Buy a well cared for, used LPE car