STREETDEMON

Well I finally got a free night during Test n' Tune at HPT. Loaded up the car and tried to get a handle on the new setup.

It was comical to say the least! First off, track prep was non existent according to the regulars. No one was running well, and even the guys on bias ply slicks weren't hooking.

That was apparent to me after my first run of the night which resulted in a 2.7 60' time...this was on street tires, so I was shooting for a 2.2.

I was able to pull out trap speeds from 111-113mph consistently all night. The only way I could get it out of the hole was to leave @ 3k rpm and ride the clutch hard...this would get me a 2.4 60'. Then any kind of powershift or anything full throttle in 2nd gear would kick the rear end out. Basically the car would spin for 2/3's to 3/4's of the track and then pick up hard in 4th. My Jeg's brand cutout was having issues with randomly closing....so time for it to go bye-bye, one more excuse for the 4" exhaust this winter. I really need to get a cold air box built around my cone filter too, IAT's were soaring throughout the night....on one run the ecu pulled all the timing and dumped me on the car's nose coming out of the hole...that was embarrassing!

With some decent tires and track prep I think the car will trap 116-117mph easy. Race weight was 3660 with me in it. I picked up 45lbs with the 8.8 swap(probably more initially, but with the tubular LCA's and Jegster Torque Arm I lost some of the gained weight in the swap).

It was a fun night to run the car, but disappointing for the street tires and track prep. Drag radials are in the budget for next Spring, just didn't have the cash/time to get it done before the tnt this outting.

AlkyIROC

Maybe, maybe not. ET depends on traction. MPH is HP. Spin off the line or hard hook and the car should run roughly the same MPH. With better traction, you'll get much better ET but you probably won't gain more than 2 MPH more, if that.

With my 32x16 slicks, I've hooked up much better on a slippery track than cars with street tires have done. Good tires no matter what the conditions are a necessity. New slicks are much better over used old slicks. Just because they have rubber still on them doesn't mean they'll hook up.

I feel drag radials are a waste of money unless you need them in a drag radial racing class. They're not designed for normal street use. They have a very short mileage life if driven on the street and they cost a lot more than a bias slick. Driving on the street runs the tires through heat and cool cycles which dries out the rubber. Once you get to the track after a lot of street driving, they won't perform as well as a set run only on the track.

Buy a second set of rims and some slicks. Take them to the track and put them on. Put your street tires back on to drive home.

112 MPH should have been good for a very low 12 second pass if the car hooks up and you get a full clean pass. If you think it will hit 117 MPH, you're going to need a roll bar since that should put you close to 11.50 or maybe slightly under.

RWB____s

what track did you make your runs at?

STREETDEMON

alkyiroc, thank you for your insight. yes i do believe there is more mph in there as i was spinning most of the track. spinning does hurt your et, no disagreement there, but it also doesn't let you put all of your hp down. and when you spin for 2/3-3/4 of the track that's well worth some mph in my opinion. as far as the drag radials, i can't justify a separate set of wheels and tires just to go racing once or twice a year. the car maybe sees 1k-1500 miles per year. if that. so a set of 255/50R16 toyo proxes tq drag radials will suit my needs just fine.

i was racing at Heartland Park in Topeka, KS. it's a little over an hour away, otherwise i would probably go to the track more.

mw66nova

iTrader: (13)

radial+clutch=broken parts.

put a biasply on it with a dedicated wheel, your drivetrain will thank me if you need tire/wheel recommendations, i have a few in mind depending on gearing.

with a 2.4 60, i don't doubt that you're losing MPH too, but i don't see 5-7 mph gain.

STREETDEMON

wrench, run, break, repeat....isn't that how it works?

still not sure a second set of running gear is in the cards....what's your thoughts for my 4.10 gear?

mw66nova

iTrader: (13)

i'd put some M/T 3053S's on it, which is a 26x10.0 stiffwall tire. put this on a 15x10 wheel and get ready for some awesome. i went 1.41 on this tire in my car

AlkyIROC

An hours drive may not seem like much until you break something and a tow truck takes you home. That's a real downside of taking a street car to the track. You always risk breaking something and when you're a long way from home, it gets even more expensive.

When we had a track within the city limits, I went to many Friday night events just to get some T&T track time. Saw lots of diffs blow up. Best was a fourth gen that stripped all the teeth off the 7-5/8" ring gear. I also saw a chevy pickup spit the pinion of a 9" out the side of the diff. Pilot bearing support breaks and there's nothing to keep it from blowing up. I've seen numerous other breakdowns during street legal night, transmissions, u-joints etc but when the track is in the city limits, getting a broken car home is much easier than one that's broke far out of town.

You're going to take your chances and if that's the closest track you have you make do with what you got. Keep spinning off the line and hope you can keep wheel spin to a minimal or hope for great traction and risk breaking something. Even with my car, every time I go down the track, I expect to break something. If I can drive the car off the trailer and into the garage under it's own power at the end of the day and not needing something fixed, it was a good day of racing.

My closest track is now a 2-1/2 hour drive so a 5 hour round trip plus a day of racing makes for a very long day. At least my diesel pulling the trailer isn't going to get hurt going down the track and I have had my car put into the trailer by a tow truck a few times.

As for gearing, you need to know what the car will do on a full pass. Depending on gear ratio, tire height and shift rpm, when properly set up with those 3 factors, you should be crossing the finish line at or just above your highest shift point in high gear (not OD). Change any of those factors and it will change the results as you cross the finish line.

In the early days of racing my car, I had a 383 SBC. TH350, 26" tall tires and 3.27 gears. I was shifting at 7000 rpm and crossed the finish line around 5000 rpm. It was shifting into high gear somewhere around the 1000 foot mark. I went to a 28" tall tire and 4.10 gears and I was crossing the finish line closer to the shift point and it dropped my ET. Current setup is 32" tall tires and 4.86 gears and I'm shifting around 7400 rpm. I'd love to go to 5.13 gears but don't want to raise the shift point even though the engine can easily do it. Shift light needs to come on just as you cross or just before. If you're geared too deep, you'll run out of RPM before you cross the finish. If the gears are not deep enough, you're leaving extra power on the table.

Before deciding on a gear change, stuff the tallest tires you can under then fenders then adjust the gearing to match the tires. Your tire choice works out to a 26" tall tire which is stock height. Depending on your shift rpm, 3.73 gears will probably be the best choice. A taller tire along with a deeper gear won't change your speedo as much as you think and it will be a better choice for the track. Tall tire has a longer footprint meaning any single point on the tire will be in contact with the ground for a longer period of time. The deeper gear will give extra torque multiplication.

You have a manual transmission but with an automatic, even a stall change will change how the vehicle will perform during a run while tire height, gears and shift point stay the same. Launch RPM can make a difference also. Automatics can use a transbrake and a 2-step. The manual transmission with a high rpm clutch drop can cause a lot of destruction to OEM parts. Learning how to slip the clutch will help but will also decrease performance.

For best performance, you want to launch around your peak torque curve and shift at the high end of the HP curve. Without dyno numbers, you just need to experiment where those numbers are.

RWB____s

I can relate to what Alky is saying. I am going through the same deal with my 3rd gen. With a SB 355, my peak torque is at 5500 rpm my Peak HP is just past 7000. With a 28in tall Drag radial and 3.90 gears I trip the lights at only 5500 rpm. no where near peak hp. I am going to try a 26in tall slicks on 10 in rims and see how much difference it makes. I am also using a T400 trans and a tight nitrous convertor. I have not made a pass on the nitrous yet. I want to square the car away before stepping up to that.

skinny z

Isn't that the truth. I'm learning my old 10.5 x 26 ET Streets don't hook like they used too. While a 1.7 60' is no prize, it's a damn site better than the 1.85-1.95 they deliver now.
Hope Castrol Raceway is kinder to me next week. I plan to get out there and race before they close for the season.

STREETDEMON

alkyiroc, quite a write-up.

i always trailer to the races, no reason not to when i've got the pickup and trailer. my dad and i used to race in a vintage class at a local air strip where i grew up. we had a 1948 english ford anglia with a bbf/t10/9" combo(2200lbs). it ran 10's in the 130's. while i have been out of the game for a few years, running down the strip isn't completely new to me. just wanting to share my experience with my new setup. currently i'm more involved in dirt track oval racing, as i married into a family that runs 4 cars at our local track(including my wife).

my 4.10s should work out well, as i was crossing the line around 6500rpm. i have the dyno results from when it was tuned, so i was using that info to base my starting points for shifting. i had 4* of advance ground in to bring the rpm range down a bit, as this car spends most of its time on the street, and i like having plenty of grunt on the bottom end.

my z28 will never be a dedicated track rat, just a fun car to enjoy in different ways. hence the reason i can't really justify a 2nd set of wheels and tires.

looking back i wish i would have left the car an automatic, but it sure is fun to bang gears with the "man pedal".

mw66nova

iTrader: (13)

i would really like to take the time to stress the importance of the bias ply tire in this situation. a radial tire will shock the crap out of the driveline. in the event you run into spin/hop/chatter type situation, they will act like an impact gun on the input shaft and other moving bits in the t56. if you have a clutch with any sort of grab to it, the clutch will not slip in these situations and you end up in the same place i am.

getting some inexpensive wheel to throw a set of $400 slicks at is an insurance type investment man. not saying you won't break parts on the biasplys vs the radials, but they are much more forgiving in this situation. a radial has it's place...it ain't on a stick shift car.

STREETDEMON

i appreciate the prodding matt. i'm months away from the tire purchase. so i will definitely baste on it. i've got the same monster level 3 that you have, it doesn't give. wish i would have gone with a 2 for street purposes. my leg gets tired in stop and go traffic, . maybe i just need to some up with a set of steelies. what kind of money are they getting for bias front runners these days?

mw66nova

iTrader: (13)

assuming your 8.8 is stock width, this would probably go over well with your dirt track racing family:

http://www.summitracing.com/parts/ae...4760/overview/

i see no reason to run bias fronts honestly. i run a 165/80r/15 "vw" tire on the front of my car with no ill effects.

Granny

A clutch slipper can really help soften that manual trans driveline shock. Just 1/10th of a second of added slip can really make a difference, effectively cutting the shock from un-damped clutch engagement basically in 1/2.

I have a customer in the UK with a really fast 1000rwhp Subaru, drivetrain strength was a problem at 8.20's in the 1/4. I sent him a clutch slipper and a month later he is running 7.80's.

I run a manual trans with drag radials on my street car, and use a clutch slipper as well. 1.30 60's, 5.73 in the 1/8th. Drive it there, drive it home, 190mi round trip. The last set of M/T 275/60 radials went 3 years, but i run a TruTrac gear diff instead of a spool.

Here's a link to a DIY Clutch Slipper, you can build one for under $50.

STREETDEMON

good idea in theory, until you have to drill a hole in your dash! i would pay extra for the biased ply tires long before i put holes in my dash. good idea for a dedicated track car however. it would be interesting to see how much faster it makes a clutch wear overtime.

mw66nova

iTrader: (13)

i've seen all sorts of versions of that thing, whether it be a hydraulic restictor, or some sort of pedal control. most of the fast stick shift guys hate these things because they can cause all sorts of premature wear and tear on the clutch. notably that they will not always allow the throwout bearing to return on it's own, and in high load conditions like in 3rd and 4th gear it could potentially cause some disc slippage.

i'll be going to a true adjustable clutch at some point. i'm over this parts breakage bit, lol.