1/4 mile launching techniques?

[Paul Workman]

Just curious to hear comparisons between launching the ZR-1s w/ stock dual mass FW and 3.45 rears vs. 13-18# (aluminum or steel) single mass FWs and 4.10s. :icon_scra Let's not narrow it to experiences w/ drag radials, but rather experiences with either gear sets on either street or drag radials. Any observations/recommendations?? And, hey...If someone wants to include some big inch LT5s, tho most of us can only dream about such things, I'd read your comments with interest too! (The more the merrier, I recon!)

P.

[jonszr1]

paul ,here what i found out with my white 92 that had a stk fly wheel and then got a fidanza . the car has 392 gears . with street tires dg3 i found that the best tire pressure was 24lbs . tried to fry them with a good burnout , but still had to leave no higher than 2200rpm and slowly push the gas peddle down to the floor (ie took about 30 ftfrom the start)then i found short shifting 1-2 @55oo really helped stop the spinning i got when i shifted at 6800. i also found that going to hiem jointed rear suspension part helped as moved alot freeier than thestk stuff did . i also took the links(upright) out of the front sway bar which helped weight transfer . burnouts are a lot easier with a line lock (pete i will bet could get you set up with one .by the by PETE is hands down the best zr1 drag racer. he has through a lot of trial and error got the tricky launch of ours cars wired . i would buy him a couple of beers and ask obwhan his secrets . with the fidanza that i have in both the black and white car i can raise my rpms up to 3300 with the mt drag radials , much lower and she boggs bad due to lack of stored inertia compared to the heavy stk flywheel . i also found that the mt 315x35 drag radials really dont work alot better than street tires . the compound is too hard . i just took delivery on the new nitto nt05 drag radials , and these tires are glue, i would put them up with the hoosiers for the best drag radials for our cars . i am going to test them for the first time tomarrow and can let you know more about them after i get back if you like. if you have been to the strip with your zr1 you will find it tons of fun blowing the unknowing minds how fast our old fat butted gals run . i have no experience with the 3.45s at the strip as the black car has 4.10 again pete could help you here as he did the majority of his runs on 3.45s . tire pressures with the mts were between 16-19 lbs . but save your dough for the good drs .jmho,goodluck

[Scrrem]

Great write-up!! :thumbsup: Doing my clutch and FW tomorrow, I'll be putting these tip to use very shortly :mrgreen:
Rich

[LGAFF]

The book in the pizza box gives some hints on drag racing and X cross:

Launch at 1700-2000

Use upshift light to shift at 5800 1-2

5900 for third......


They also note to use Sport to reduce wheel hop.


Also they state for Xcross to set front tires at 36 and rears lower at 32PSI

[Aurora40]

You definitely want to run higher than 5,800-5,900. Even stock the power doesn't drop off that badly, and modded it will keep making power to almost 7k.

[LGAFF]

Thats for stock, I shift at 7200 or so.

[rkreigh]

the ZR-1 is a very tricky beast to launch

it takes lot of practice to get the 60 ft below 2.0

I've gotten quite a few 1.77s but more luck than anything else

because the car is setup to handle, it doensn't weight transfer all that well and the contact patch gets worse as the car does because of the IRS

gears, ,flywheel, torq clutch type, tires, ,EVERYTHING influences the lanuch but here goes on a few general guidelines

with the dual mass, you have much more intertia, 4.10 gears help, but only if you are talented enough to slip the clutch or have very good tires

I have a 390 LPE making 508 rwhp, about 430 rwtrq, with 4.10 gears, fidanza, stock clutch (that's the type of info we'll need to help advise you)

with the fidanza, and drag radials, I can come out about 3200 and let the clutch up rapidly to get that 1.77 best ET 11.47, best MPH 128

pete can do that with less rwhp due to practice and skill. lots of both are needed to find that "perfect launch point"

so here's a few more tips, with street tires, big burn outs don't help much, and depending on the drag radial or slick, getting the tires in the "water box" and getting them good and hot will dramatically help the launch

assuming those Nt05 or hoosiers (GREAT tires), you can up the launch rpms to between 3600 - 4400

the goal is to apply as much torq as possible without breaking or spinning with a clean launch without bogging the engine (very hard to do)

I find slipping the clutch really helps, but it's also very hard on it

right after your burnout, you can do a dry hop and see how the car responds to a particular launch, but the ideal launch rpm varies by car, how sticky the track is, and all those variables listed above

it takes quite a bit of experimentation. read some posts by pete and ranger (he also wrote in corvette enthusiast)

log what you do each time, and slowly ramp up the launch rpms and clutch release technique to keep decreasing the 60 ft time

every tenth there is worth almost 2 on the big end, but remember, the ZR-1 isn't much of a drag car.

my little old drag car with a solid rear (and about the same rwhp, torq as the LSV) is setup with a 4 link, solid 9 inch rear, and cuts 60 ft times of 1.35, runs 9.20s, at 142 mph, it's lighter, and has about 480 fts of torq, but it's and automatic, and really puts the power down

FYI, if you want some really good tires, I have some hoosier 17 335s for sale, 350 + shipping, I have 2 sets that I bought, and really don't run the ZR-1 much anymore (too nice to tear up)

tires and technique, those are the best two tips I can give you. tires are ez to figure out, technique takes practice and refinement, but IMHO, don't even bother on street tires, too inconsistent, and the sidewalls are too stiff.

nothing tears up the drivetrain like wheel hop. when you start to hop, back out of it and try again, it's not worth all the breakage:razz:

[XfireZ51]

Anybody have any experience launching with the GY F1 Supercars?

[rkreigh]

Anybody have any experience launching with the GY F1 Supercars?

yes, but in the 325 30 19 z06 side stick tire, not nearly as good as drag radials land very prone to wheel hop due to the stiff "run flat" sidewalls

I got down to 1.8 and run 11.65 at 128 by takin it easy out of the whole, I think I launched at 2800 and squeezed it

with the full hoosters, the clutch becomes the limiting factor as I can come out much harder and still hook, more like 4000, but grenaded a fresh clutch with 2k miles the first time a tried.

you need to finese the clutch action to get just the right amount of slip and then ful relase to hook up and not bog

the street tires make this harder, and avoid wheel hop or you can eaisly break things or lose control (*or a filling for that matter *:mrgreen:

[Jim Nolan]

Several years ago at a Gathering John Lingenfelter was the center of a bull session and somebody asked him which ride selection, in his opinion, was best for drag racing. His answer was.....Think about it, which ride selection has the has the most movement? Touring, the front rises and the rear drops down. This puts the most pressure on the rear tires and this is what you want to get better traction. His opinion, just food for thought.

[rkreigh]

you want the weight transfer but the c4 independent rear doesn't maintian the best camber to keep the full tire plated when it squats

I worre the inside edges of the gy run flats out pretty quickly at bg making runs.

a flexibly sidewal tire takes the dump of the clutch and wraps up the tire more and will plant "at non optimal camber" angles must better

the really high power cars are a bit squirley, and the c beam flexes unloading one tire more than the other from the diff twisting

hook hard and roll on the throttle rather than dumping the clutch has been the only think that works which infolves slipping the clutch and then putting it to the floor after the 60 ft. eve then sometimes it breaks loose

with the hoosiers, I can come out hard! hope to see a 1.6 and not break anyting with a more talented clutch foot

f1s are lousy drag tires, don't like em on the street either. they handle well but don't hook up even with the 325 c6 size

[XfireZ51]

Ron,

I guess I get to try the 19" 325s and see. I have found that Performance works better for launch. Mine has the Marracca valved shocks. Any thoughts on launch with lowered rear?

[jonszr1]

on my white 92 which is about 11/2 in lower than standard but also has coilovers .i lowered the bump stop on each side so that the half shafts didnt go into the negative angle as bill told me thats a good way to break things . i use the middle setting on the fx3. i am still getting used to the new nitto drag tires (nto5r) they show great promise though. its looking that 26-24 are going to be the best pressures to run with these tires and leave around 3500

[rkreigh]

setting up the car for the digs involved some real compromise for handling

in essence, you can have a good drag car, or a car that handles

the FX3 can be setup with the custom controller (removable control chip) to allow front shocks soft and rear stiff to allow weight transfer, but not too much squat. I like the limiting idea on the bump stops, and also unbolting the front sway bar end links helps "free up" the travel

don't even bother on the supercar F1s, the sidewalls are rock hard and really only a good drag radial is worth going out there. street tires just don't cut it unless you really finesse the throttle and clutch

those NT05Rs look really good, but the 19' small sidewall hurts the launch as you want a "tall" tire with a deeper sidewall give to allow the rear tires to bite, but certainly they are going to hook pretty well

really a slick is what you need, but the zr-1 spindles and half shafts are "vulernable" when launching hard and hooking

great thread, Pete, where are you buddy

pete, haibeck, and my buddy phil can drive pick up several tenths on me anyday. practice and the nut behind the wheel make a huge difference

[jonszr1]

where can one get a custom controller????

[Paul Workman]

on my white 92 which is about 11/2 in lower than standard but also has coilovers .i lowered the bump stop on each side so that the half shafts didnt go into the negative angle as bill told me thats a good way to break things . i use the middle setting on the fx3. i am still getting used to the new nitto drag tires (nto5r) they show great promise though. its looking that 26-24 are going to be the best pressures to run with these tires and leave around 3500

I appreciate your (all others too) comments. Is your launch at 3500 is with a light weight (Al?) FW, right?

P.

[jonszr1]

yes, its 3500 with the mickeys , i just got off the phone with the nitto guys and found out i should try going to 27-30 lbs and try going up 500 rpm .which i will do tomarrow at the summit series race at famoso, during the practice runs . if you are going to use street tires and a fidanza flywheel i would suggest starting off around 2000 and step up from there in 200 rpm incraments . get a legal pad and keep good notes of each run . i fo that and use a gtech pro rr that has a download program that shows wheel spin, exact shift rpm, length of time it takes me to shift.plus a bunch more stuff. it also has a shift light . i really like it . plus you can use it off the strip ifyou want to try something away from the track.hope this helps