Researching an 84 C4 LS1 powered road racer build

[subtlez28]

I just scored an LS1 powered 84 C4 on Ebay this week.
http://cgi.ebay.com/ebaymotors/ws/eB...m=180255460141

I wasn't really in the market (I was going to build my Buick into an L92/T56 powered road racer), but couldn't resist it! I've wanted an LS1 powered C4 since reading mojave's page:
http://www.mowhineracing.com/index.html

Anyway, I think I got alot of parts for the $. I'm a little bummed that it appears I will be paying another $1000 to have it shipped up here.

And don't worry, that auto trans will come out ASAP, and it will get a liberty face-plated T56 (already in my garage).

I'm in the researching stage of making this a competent road track car (but still street legal, and likely in a street tire class).

Any insight would be appreciated.

Any links to other places to get info also appreciated.

I already know the brakes on early C4s are smaller, direct info on C5 conversion would be helpful. I already have a full C5 set up that was going onto my Buick project.

I've taken my Z28 as far as I'm willing to go. I want to use this car as an excuse to rip out dead weight like a/c and similar unneeded items. I read on here that some LS1 C4 swaps are in the 2700 lb range. If thats true this should be a much quicker road course car than my Z28 (which is already doing well in my local street tire class).

Thanks in advance!

[dailydriver]

I always thought/heard that face plating was only for drag racing??
(i.e.; that you could not downshift it quickly enough to be useful in road racing, or even on the street?)

[subtlez28]

I was actually wondering about the downshifting thing after my race yesterday. Its very hard to heel-toe the 02 Z28, hopefully the Vette pedals work better, cause I imagine hoe-toeing will be needed.

You may be right.

[EchoMirage]

Originally Posted by subtlez28

I was actually wondering about the downshifting thing after my race yesterday. Its very hard to heel-toe the 02 Z28, hopefully the Vette pedals work better, cause I imagine hoe-toeing will be needed.

You may be right.

what method of downshifting are you using. there were several threads about this a year ago or so. you dont 'heel-toe'. at least not in our cars. what you do is keep your left half of your right foot on the brake, while rolling the right half (like your pinky toe) over to blip the gas. i do this on the street and track, and works perfectly.

[subtlez28]

I think if I put on a wider cover on the gas pedal (or piece of plexi-glass, as I've seen others do) I could do like you say. But, as is, pedal placement makes it pretty difficult.

For now I'm just clutching while I brake, grabbing the appropriate gear, and timing the release so it doesn't upset the car at an inopportune time. I realize this is not the best method. I intend to work on the method you mention.

[EchoMirage]

i found it out myself. works fine. i did also get a set of new screw in pedals. replaces the rubber covers on the clutch and brake, and has a bigger metal piece you screw into the gas. also has an added kickout-like piece on the gas pedal, making throttle blips even easier. i have the link to a comparable set of pedals if youre intersted.

[Mojave]

Sadly, 84 is the step child of brakes. The best way to do a C5 swap is to find a pair of 85-87 (88-96 won't fit) spindles and then get C5 swap brackets. After that, it's the same as a C5 swap on an f-body. The 84 spindles have smaller holes and it's questionable to drill them out for the bigger bolts.

http://forums.corvetteforum.com/show...=c5+brake+swap

I'm jealous of your LS1. My car completely full of gas weighs 2900 lbs, and that was with the iron block LT4. With 5 gallons of gas, it weighs 2800 lbs. Dropping another 75 lbs off of the nose will get it into the 2700 lbs range, and I still have a lot of weight left to go.

As far as the trans swap, the hardest part will be the c-beam mount. AFAIK, there isn't a good, bolt in T-56 c-beam mount bracket. There was one for sale, but the quality was questionable. The people who have done this swap made their own. Also, the T-56 is a bit longer than a ZF6, so you will have to do something with the c-beam and the driveshaft. If you do end up making one, I really believe there is a market for selling them on Corvette Forum, as that is the last part for a complete, bolt in LS1 swap into a C4 with a T-56.

Looks like it already has VB&P springs and bars plus Konis, which is a nice upgrade. That is a great place to start on the suspension setup.

C4 pedals are noticeably closer together than f-body pedals. I heal-toe with no issues with stock pedals and sneakers.

[subtlez28]

Thanks mojave. Bummer about having to swap spindles.... I already have the other C5 stuff, and I busted my budget just buying the car (this was my Buick project $).

How different are the C5 control arms and spindles from the C4 stuff?
I have a line on a set of C5 control arms and uprights. I suppose it is too much to hope for...

[subtlez28]

Oh, also it has a 98 LS1 and harness. I remember reading the 98 is less desirable... and I read a post on (of yours mojave) CF that 98s have oiling issues also.

I'm sure this info is available elsewhere, but I'm searching and reading like crazy, so a short, simple answer or link would be very helpful. What's wrong w the old 98, and how do I fix it (it has the f-body pan-please tell me this is a vette related issue)?

So I have the step-child brakes, w step-child wheel offset, and the step-child year LS1...
Still though, I have and LS1 and a Vette...I'm still happy!

[Mojave]

Originally Posted by subtlez28

Thanks mojave. Bummer about having to swap spindles.... I already have the other C5 stuff, and I busted my budget just buying the car (this was my Buick project $).

How different are the C5 control arms and spindles from the C4 stuff?
I have a line on a set of C5 control arms and uprights. I suppose it is too much to hope for...

The C5 controls arms are totally different. They don't even attach in the same way.

Originally Posted by subtlez28

Oh, also it has a 98 LS1 and harness. I remember reading the 98 is less desirable... and I read a post on (of yours mojave) CF that 98s have oiling issues also.

I'm sure this info is available elsewhere, but I'm searching and reading like crazy, so a short, simple answer or link would be very helpful. What's wrong w the old 98, and how do I fix it (it has the f-body pan-please tell me this is a vette related issue)?

So I have the step-child brakes, w step-child wheel offset, and the step-child year LS1...
Still though, I have and LS1 and a Vette...I'm still happy!

The 97-98 use a different harness and PCM than the 99 up. If you're getting it tuned, 97-98 take different software. Also, they use the perimeter bolt valve covers instead of the center bolt ones. Neither are deal breakers, but just more hassles if you're messing with it.

All the early LS1's had issues with oil going up the right side of the block in long left handers causing oil starvation. I want to say GM fixed it on the LS6's (or maybe it was all 02's and up, I can't remember). I'd try one of these:

http://improvedracing.com/

The guy who makes these showed up on Frrax. He claims they work pretty well on his LS1 FD RX7. This should greatly help the problem. An Accusump is also a wise investment.

[subtlez28]

Thanks for that link Mojave! I definitely see one (or two or three) of those in my future!

I was considering a canton pan, but really like the cast stock pan better.

I searched on the 98 issues. Thanks for the short version. I don't mind the computer issues, or valve covers, but I read the oil passages in the block are smaller, and the heads don't flow as well. Thats a bummer!

The good news on the long sweeping left handers is, all three tracks I race at run clockwise. So, its mostly sweeping right handers. Guess I need to stay away from oval tracks!

[gnx7]

That sounds like a fun project. I would use an aluminum flywheel if you want it to rev fast. They are worth the extra cost.

Also overfill the oil pan by 1 quart.... helps to keep the motor alive when racing. It will not cause any harm and I do it on mine.

I think even with the C5 brakes you will need to upgrade them if you push the car hard enuf. Get some good race pads for sure and swap them in when going to the track!

In addition you should install ARP or Katech rod bolts. '99 and older motors had inferior bolts and could let go when pushed hard. I replaced them in my '99 shortblock and then drove the car hard for 20K miles with a 7100rpm redline that was touched every day. It had about 10 hrs worth of road race time on it without any issues. Overfill by 1 quart for sure.

Good luck!

-Mark

[subtlez28]

Car is in the garage.
I'll add pics soon.
Any more input?