CorvetteC5Norway

Last fall I bought a mint 98 vert 6m with approx 40' miles. The first winter I upgraded the suspension with Z06/Z51 parts (springs, sways and shocks)
I have to say I am really happy with the car, and have tracked it a couple of times during the summer. It is now really a contender on the track, no problem keeping up with the Porsches thru the turns. The engine seems in perfect condition, no oil usage or any hickups.

This winter I thought of getting the engine fine tuned. I have changed all the oils, but I guess due to the cars age there is more that should be upgraded. I'm thinking of spark plugs, fuel filter etc.

I also want to get the most out of the standard engine, so I'm thinking of the so-called bolt-on's and a tune. I have today a Magnaflow axle back and a cheap dual cone intake. I know that the gamechanger is long tubes, but it's a vert som I think it will be to much sound.

So the question is; what should I get changed / serviced and what bolt on's (except LT) should I go for? My goal would be 400 crank hp if possible.

All thoughts are appreciated!

Blow Torch

If you leave the cats, I don't think the headers will be too loud, but be a GREAT power producer. It will be difficult to get to 400 with bolt-ons without LTs. The magnaflows are deep but not very loud.
Good bang for buck bolt-ons would be LTs, vararam (the cone wont do much) but at speed the vararam WILL) a 01 higher (Z06) intake and a tune. That should get you in the 335-340rwhp range, which is close to 400whp

If that's 40,000+ miles, then combined with the age, go ahead and change all of the fluids, (except antifreeze) fuel filter, plugs and wires. (cheap insurance)

CorvetteC5Norway

Thanks for the feedback. When you say z06 intake, is that the part between the airbridge and the intake manifold?
And what about the intakemanifold; I see that many people change to a FAST manifold. Will that add power that justifies the price?

Another thing; I guess the harmonic balancer is soon due. It has an ever so slight woble. It has not gotten worce on the 5000 miles I have driven this year, but still. When changing it, isn't it quite easy to change to another cam? Again, does it give power to justify price?

Thanks again for feedback.

Emerica88

Nothing will be worth it if you don't do headers

grantv

What I consider bolt-ons is bolt-ons; headers, manifolds, etc. If you're looking for 400HP you can get close with headers and intake (don't think a Fast manifold is worth it). Not quite though I'd think (380-390?).
Without headers you'll have to get a cam, and a set of 243 (LS6, Z06) heads would be great.
Headers won't make the car much louder, and are a great path to make power; 400HP is an easy goal, but harder without that performance staple.

Blow Torch

I'm referring to the intake manifold. (sits between the heads) I don't feel the FAST justifies the price on a basically stock engine. Need H/C to use the increased flow.
If you have to pull the balancer, then yes, stick a cam in. (along with an underdrive pulley) Depending on the size, you can get a GREAT increase in power with a cam swap. You will have most of the hard work done (steering rack removal) but I don't consider that a bolt on as per your original question.

vettenuts

Unless you can find a used FAST 78. Otherwise, LS6 intake can be found used. I don't think the Magnaflows are very loud to start with, so the headers may not be objectionable. I have them on my vert and each modification made it louder, but it was the cam and heads that made the biggest difference in sound. Since you don't want to do cam and heads, don't think the sound is an issue. I run mine with the Z06 titanium cat back exhaust.

CorvetteC5Norway

One of the reasons I want to keep the noice down is that I do the occasional trackday, and they have pretty strict noice regulations...

So maybe a cam, varam and a Z06 intake could give me a nice bump in power(not so far from 400)?

About the tune; do I need to find a garage that live-tune it on the dyno, or is it possible to have someone make the tune based on what modifications is done to the engine?

CorvetteC5Norway

ok, maybe I need to go the longtube way...

a quick glance at ebay tells me that it's two sizes; 1 3/4" and 1 7/8"

What should I go for and why?

I guess if I go that way, I should do the whole "plumbing" right up to the axle back included the x-pipe and cat. Or is it ok to just do the actual headers?

And finally brands. I've read here that LG and Kooks is the way to go. Is there other good brands? Dynatech? BBK?

Andrew

If noise is a concern, I can tell you that a set of LT's with cats and a Z06 titanium axle back is not that noisy and sounds great. Plus you will have LT's. Not that much more noise than a stock Z06. Unless you are getting a much larger CAM and / or going FI, you will not notice much difference between a 1 3/4 and 1 7/8 primary header system. As for vendors, the one's you mentioned are good. I chose the latest generation of XSPower. Other than a few fitment issues, a good set.

Although I am in a Z, after installing Vararam and LT's, it tripped the CEL. I chose to get it dyno tuned, which I would recommend. It is better than going the mail order route, although there are some really good mail order vendors around. Just make sure that whoever tunes it knows what they are doing. It can mean the difference in several horses as well as keeping the motor together.

Is your goal 400 crank or 400 rwhp out of the otherwise stock LS1? Either way, probably will take more than LT's and an intake. If 400 rwhp is the goal, will take much more than LT's and intake.

Have fun with the build!

Bleachcola

Got a coupe with long tubes , no mufflers no cats

Sounds awesome , suprised how quiet it is while normal cruising

CorvetteC5Norway

The goal is 400 at crank, give or take. I've upgraded most of the suspension to z06/z51, so it could be fun to get the power up to and have wannabe z06 vert ☺

grantv

Then you have a few options as noted above.
If you're happy with less than 400; headers, intake and tune will get a nice bump.
If you want to hit the 405/Z06 mark; you'll have to go inside. Cam at least, with better heads better yet. Headers would still make this target easier.
Pick a cam vendor, tell them if you're doing heads and or headers, your goal, and there you go. Make sure you ask what else they recommend for the cam install (springs, seals, new chain, HB...?).

Andrew

Yep, agree 100%. Here is a link to a very cool post, illustrating the HP gains throughout many modifications. I often refer to it when thinking about modifications. Although this was done on a Z06, you can see the gains and should be fairly applicable to the LS1. If this is the same Toque, he is also a member here.

http://www.digitalcorvettes.com/foru...d.php?t=162317

My results were similar with LT's, Vararam and tune. You will see that a gain of 9.2 percent rwhp was gained. I know this is apples to oranges, but this should get your crank hp to somewhere around 375. Getting the other 25 hp would be a real challenge. After the LT's and Vararam, maybe adding a electric water pump and smaller pulleys could get you close. My bet is that you would still be lower than a stock Z06. Could be wrong.

What is more important is the torque increases throughout the power band. Without a new intake, this is really what you are needing. To get to the 405 crank hp number, you will need to push the rpm's up while holding the torque. As mentioned, to do this efficiently, you will also need better cam and heads. Also, the stock Z06 manifold starts to break up over 6200 rpm or so, meaning that the car stops making torque above this and starts falling soon after (see the results of the link above - my car did the same thing). Not sure what the LS1 manifold is like, but guessing that it starts breaking up somewhere under 6200. Then you will need a clutch, injectors and the parts start to increase and become expensive very quickly.

Before purchasing a air filter kit, take a look at the Vararam site. The Vararam does not add power on the dyno, but on the road, it will keep the power up on the motor due to sucking in much lower temperature than pulling air from under the hood. Your motor likes cooler air. The only other option would be to go with another brand and cut out a hole in the plastic casing, under the air box. Without doing this, you are still pulling air from under the hood, increasing your IAT. You will be amazed how the motor keeps pulling, due to pulling in cooler air.

grantv

I'm on my phone so harder to check, but I think Toque's site is www.toquez06.com Great site.
The 9% is pretty much right on for headers and a MO tune.

CorvetteC5Norway

Thanks guys, I'm starting to get the picture. I'm tempted to do LT's with x-pipe, varam and intake this "round". When you start opening the engine, well you are in a new ballpark....

Gordy M

Since you are going to track the car here a a few options to thinks about. For power gains, you can go the Z06 route and add a cam/intake from a 2002-4 Corvette. Then add the long tube headers and a true Cold Air intake. Once that is done, find a tuner who can tune it at the track and make several track runs as he is tuning it. Depending on the tracks you run would greatly influence the CAI you would get. If you hit 140+ mph ( I think that would be about 225KPM) get a thru the front License Plate opening or Calloway type CAI. I you run at tracks going less than 140 you can add VeraRam to the list. A dyno will give you good WOT tuning but does nothing to help below the cam or torque curves. live log/scan tuning can give you that data as well as removing the drive by wire lag. The Z06 intake adds little hp but is great for adding torque to your motor. I have run numerous track with most of the time the car is living in third and fourth gear and accelerating out of a corner you want torque more than hp. At the end of the straight you want the hp for higher speed. HTH

Roddy13

^^ This!

You'll need a cam to get up around 400whp.

If you just want bolt ons, I would go Vararam, ported TB, LS6 Intake and Long tubes with mid-pipe... if you want to keep it quiet sell your magnaflow axle back and put the stock axleback back on. All of this with a Tune you will see 335whp IMO.