Then I'd be getting spead port heads/headers. Transzilla has one the biggest transmisions

 

Nice running car, dude. I also run MT ET Street Radials and they do hook very well on C3s. The better the track prep, the better the hook, but don't treat them like bias ply slicks; use as much air pressure as you can get away with.

Start with around 24 lbs. and work your way down to around 20 lbs. They are made to perform best at these pressures.....remember, these are not wrinkle wall slicks. The compound is actually stickier than ET Street bias slicks. And, using a stiff rather than soft rear spring helps more.....less rear squat, let the tire do its job.

Also burnout procedure - no need to bury the crowd in white smoke.....initially give one "good" burnout to heat and clean, then on consequent runs only a quick one is needed. I use a heated 22 lbs. on mine and 60' @ 1.50 with good track prep and 1.60 in fair conditions.

 

I poked around under the car looking at the linkage. I didn't see anything out of wack. All the bushings and linkage seemed fine. I was investigating the Z bar, and noticed the pivot ball in the block was pretty loose. Afer tightening things up it seems much more stable. I also adjusted the clutch while I was at it. Oh yeah, it sure smells like clutch disc under the car.

Another good find was I noticed the #7 spark plug boot wasn't clipped on it was barely hanging on by the boot on the tip of the spark plug. Crazy and embarrassing how well it runs on 7 cylinders.:o

Gkull, I doubt at this point in the game I'll change out the heads, but I appreciate your input. I considered raised port heads, but not spread ports. I guess I didn't want to increase the challenge hunting down headers.

There are a lot of killer cars in this post. I hope with everyones help I can get this thing dialed in. I see Rock Falls Raceway (Wisconsin) has a fun run day this saturday, and a muscle car shootout this sunday. I'm asking around for a trailer. If my clutch holds tomorrow, and I can get a trailer, I'll head out for a few passes. I'll keep everyone posted.

 

Does MT make 2 different style street slicks because my thread looks different than the picture in the first post? Mine doesnt have the curved lines near the outside edges and only has 2 lines in the middle and a dashed line near the outside edge.. Just wondering which one is a better compound for the street.

 

I noticed that they have a few different versions too. I went with the advice of the race shop I deal with, he knows I like to drive the car, not only race it. The tires needed to be DOT, and sticky. I'm happy with his advice. I like the idea that it looks a little bit like a "tire".

From what I can interpet on the Mickey Thompson Webpage, I'd say between the ET Street, and the ET Street Radial, the ET Street Radial has a softer compound and would give better bite.
http://www.mickeythompsontires.com/tech.php?bulletin=s1

 

That figures, I have the ET Street's...

 

I would say the compounds are about equal. My et streets hook harded, but they have more sidewall and do not have the radial structure perform better in street driving though.

Btw Blwn73 I would be interested to see what your car does on a chassis dyno just to see a good look at what drivetrain loss might actually be.

 

There was a chassis dyno about 7 miles from my house. I drove over as soon as I took the car out for the summer. I pulled in all the signs were in the doors, billboard outside, but they were out of business. Had I known, I would have dyno'd in the fall.

My exact thoughts. I was very interested in finding out the drivetrain loss since I had the flywheel hp numbers. I know the speed shop TNT Performance made mention of another chassis dyno in the area. I'll have to ask. I don't necessarily need the tune, but it would be nice to do a few pulls, and maybe hit the NOS at low boost and get some numbers.

I'm skipping the gym tonight so I can make a few launches, and or 1/8 mile passes after work. It's about 67 degrees and sunny outside. I'm concerned about the clutch more then any hard parts. We'll see.

 

Nice! I plan on doing the same two dyno deal when I get my 71 running again. I want to know as close as I can the drivetrain loss.

 

Having used both the ET Streets (bias, wrinkle wall), and the ET Street Radial, I have found the Radials to have a much superior bite. The Radials compound is definitely stickier, you get a much smoother ride down the track, less rolling resistance, and none of the usual "ballooning" at the top end.

 

The evening runs are done. Three different launch rpms. I finished one full 1/4 pass, and one 1/8 pass. Transmission is shifting pretty good, and the clutch is grabbing pretty good.

Tire pressure is set at 33 psi. The first test launch at 3000 rpms produced a lot of wheel spin I looked at but didn't even record any time. Launches at or above 2500 still blow the tires out from under the car off the line. A 2000 rpm launch worked pretty good.

1/8th mile pass 2000 rpm launch (pretty good hook and straight)
Distance, ET, MPH, G's
1/4, 12.41, 98.3, 0
1/8, 8.18, 96.3, .39
330', 5.58, 75.1, .52
60', 2.37, 35.2, .74
30', 1.63, 23.9, .66
15' 1.19, 17.5, .67
0-60 mph 3.96 at 173'
0-30 mph 2.04 at 45'
Peak G's .823 at 44.7mph at 93'

1/4 pass 2500rpm launch (Sideways out of the hole)
Distance, ET, MPH, G's
1/4, 12.62, 121.3, .25
1/8, 8.53, 96.5, .37
330', 5.92, 74.5, .49
60', 2.63, 32.9, .74
30', 1.83, 21.4, .55
15' 1.34, 15.8, .54
0-60 mph 4.41 at 183'
0-30 mph 2.45 at 52'
Peak G's .801 at 36.5mph at 71'

I can really see where the wheel spin effects the ET's. I'll probably need more power or a gear change to really get my 60' times down.

I'm thinking I'll drop a 5-10 psi on the tire pressure and see if I can launch above 2500 rpms.

I do like the trap speed of 121.3mph, that is promising.

Oh oh, now I'm thinking NOS in 2nd, or swapping my pulleys around on the blower for a little extra get up and go.

Yep, this is fun.

I'll find out tomorrow if I can borrow a coworkers trailer and head to the track this weekend.

 

LS1/6 guys don't run 2+ headers so why do you feel you need to on oldschool motors...new motors have better head flow etc. and pro tuners don't use big headers so I say that is a false assumption but that is my 2cents only. only BB racers motors need 2-1/8 and do perfectly fine on street with 2"

 

LT1driver: As far as header size is concerned, I look at it like this, at full boost I'm displacing around 600ci. Throw some NOS on top of it, and it would seem that what ever a street strip 540ci motor needs will be a good starting point. As I recall, the entry size for the primary pipes are 1 7/8" on ls1 camaro's and vettes. I'll most likely go with 2" since it's a vehicle that will see only occasional strip visits. Blown motors don't lose any noticable low end with the big primaries, and pull hard at the top end. My 2 cents thanks for your opinion.

 

I agree.... On a 680hp motor I would have 2" headers on it.....also the biggest/best flowing exhaust from the headers back you can afford...


As for your runs..... You need to run no more then 25 psi in those tires when normal driving, then for playing around you need em around 18 psi.....33 psi is WAY too much and likely killing the contact patch and keeping the tire too stiff. Also, you will need to do a burn out prior to a run. Lastly, try to find a good road with some fresh, white concrete...., or maybe something knurled like a feeder road to a local freeway.....And even with all this, that thing is still gonna spin like crazy... Only chance you are gonna have is to get it on a well prepped strip....and pray the rear end holds together...


And for chrissakes, take some freakin in car video and post it up here damn it.

 

there is a chassis dyno in elk river on highway10 its called hi-tech motor sports or something like that

 

Based off your MPH, with traction, it looks like your already in the low 11's

 

ajrothm: What size primaries would you say for 725hp+? I only stopped at 686hp because I didn't have any more pulleys available to dial it in higher. I should try to scan and post a few dyno sheets. The power dropped on the top end at 6psi, like it needed bigger headers, or cam phase tuning.

It sounds like I'm on the right track in terms of dropping the tire pressure. MT's site said to start at 75%-100% of max inflated value (44psi) hense the 33psi starting point. I'll drop them down to 25psi for the next testing session. Eventually I'll do a test at 16psi or so, but first I'd like to know what it runs set up how I get in and drive it everyday.

There are a couple freeway areas that have concrete that I would consider knurled. It's a sunday morning area or late evening spot because of traffic. Traffic is always an issue. Gotta keep it safe for me, and others.

I tried to tape a string to my blackberry and video the run. the angle was all wrong. I'll try to work something out and get a video. My wife won't ride in the car. so she won't shoot a video.

mvette76: Thanks, I googled chassis dyno and found that one last night. I may talk to them about re-ringing my motor, engine dynoing, and then I'd throw it on their chassis dyno. Thanks for the info. It's only $75 for two pulls without tuning. Maybe I'll take a day off and schedule a session. Cool.

Fishndude: I like the sounds of that! My current goal was to see a high 11, so I'm getting close. Thanks for the encouragement.

The weather looks questionable until the end of the week, so it'll be bit before I can do anymore tests.

 

Combined with header size you really need to look at primary length, collector size and also where the exhaust ends. The exhaust pulse can force a car to lose a decent amount of torque over the midrange if you do not have the proper exhaust setup. I have seen it on the dyno with my Z06. I was losing around 50 ft-lbs of rwtq on the car due to where the exhaust system was ending and how it was impacting the exhaust pulse.

 

sigforty: I agree, I plan on discussing the primary length size, and collector size with Headers by Ed, and Stahl as I move forward. I may buy them direct from Stahl, or have Headers by Ed build be a custom set. The cost is about the same. My skill at that level of detailed welding, well, not so good. l had a 460 ford in a pig torino many moons ago that couldn't bark the tires. I installed a set of hooker super comps, and smoked the tires sideways down the street. My 500hp 144 blower motor picked up 15hp and 10trq across the whole powerband going from 1 5/8 to 1 3/4 headers. Of course the primary length was different also. Good comment and a good reworld example of proof. Nice.

My current setup has 1 3/4" super comps, with a 3" exhaust to 40 series flowmasters. I'm thinking I may keep the 3" exhaust and run some electric cutouts.

How did you figure out the optimum exhaust for your Z06?

 

73Blwn, I would probably stick with 2" primaries and 3" collectors. If anything for fitment and have some kind of plug access. You don't want to hurt the off boost response...especially considering it's already a low compression motor that is probably a little soft until 3000 when you get some significant boost coming in. Also VERY important is the exhaust system. You need atleast 3", preferbly mandrel bent with as few bends as possible...and for gawdsakes get rid of those chokemasters. Get some Dynomax ultraflows, Pypes Racepros or Aerochambers. You are probably losing 20hp in the chokemasters alone at your HP level.

Good luck at the track. I look forward to seeing the numbers....I imagine you will trap 125mph plus....probably more like 128-129mph if it hooks in 1st and you nail the shifts.