Author Topic: How the heck do I make my car 60' worth a darn  (Read 1178 times)

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neat

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How the heck do I make my car 60' worth a darn
« on: August 26, 2005, 12:07:19 pm »
I have owned 2 C4's, and neither of them would 60 foot worth a damn. Both have been 6 speed cars. The first was a 92 vette with a 383 stroker. It made about 380 RWTQ NA, and a little over 600 RWTQ on the bottle. On ET streets I would rev the engine to 6k, drop the clutch, and press the throttle the rest of the way to the floor. The tires would dead hook and the clutch wouldn't slip. The best 60 I ever cut with this method was a 1.81.

The car I have now is a 91 6 speed. It's pretty stock, just longtube headers and nitrous. With the same launch technique it won't sixty foot any better. Obviously I only rev the stock TPI to about 4500 on the launch, but I drop the clutch, floor it, and the tires dead hook. Mid 1.8's all day.

Both cars have the stock 3.45 gears.

Ryan, Brandon, or anyone else with some C4 experience have any thoughts?
« Last Edit: August 27, 2005, 10:11:48 am by DaBo_Z28 »

Offline GeoffWhite

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Re: How the hell do I make my car 60' worth a damn
« Reply #1 on: August 26, 2005, 12:53:28 pm »
Buy Ryan's 4.10 gearset!
http://www.cardomain.com/ride/410627
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Offline The Sad

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Re: How the hell do I make my car 60' worth a damn
« Reply #2 on: August 26, 2005, 04:53:09 pm »
You know, I have been asking the same question about my car.   

I think the solution is more POWER!!!  Suspension tuning be darned!

The SS looks like it could kick your ass, the WS6 looks like it's coming over to do it!

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neat

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Re: How the hell do I make my car 60' worth a damn
« Reply #3 on: August 26, 2005, 08:22:20 pm »
Lol.  Isn't your car an auto?  Stall and slicks, problem solved.  GHOSTRACER was cutting freakin' 1.5's on stock suspension, slicks, and a stall with his 98 Formula.

Offline The Sad

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Re: How the heck do I make my car 60' worth a darn
« Reply #4 on: August 27, 2005, 12:38:51 pm »
Yeah, I think I need a bigger stall.

Maybe you should get adjustable shocks.

The SS looks like it could kick your ass, the WS6 looks like it's coming over to do it!

99 Trans Am WS6 - a few mods ;)
06 YAMAHA Raptor
06 YAMAHA R1
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neat

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Re: How the heck do I make my car 60' worth a darn
« Reply #5 on: August 27, 2005, 02:29:24 pm »
Adjustable shocks to increase weight transfer, to increase traction, is a moot point.  I am dead hooking the tires I have now.  I have all the traction I need.  When I drop the clutch, the car lurches forward, and the motor almost instantly bogs.  This results in 1.8XX times.

I am thinking more power (leaving the line on the juice), or lower gears.  4.10's or something.

Here's my extended theory on this.  With a manual transmission, vehicle speed and engine RPM are linked.  Speed 'A' equals RPM 'B'.  There is no slop, no play, no nothing.  Unless the clutch is slipping, speed and RPM are linked.  The engine in my car doesn't really start to make power until 3500 RMP or so.  When I launch the car, and the tires don't spin, vehicle speed and RPM are linked.  Vehicle speed is zero, so the RPM's instantly start to fall, in an attempt to be linked with speed.  Speed also increases in an attempt to match RPM.  3500 RPM's in first gear is roughly 25 MPH.  To launch the car effectively I have to slingshot the car from a stand still to 25 MPH.  To accomplsh that, I need a massive amount of horsepower.  The inital hit must be so great, it's hard to quantify.  Catapaulting 3300 lbs. to 25 mph in less than a second takes a tremendous amount of force.  The other solution is to lower the MPH (yes, MPH, not RPM) where the engine really starts to make power vai gear swap.  With a 4.10 gear I would reach my power producing 3500 RPM's at 22 MPH, VS my previous 25 MPH.  Not a staggering improvement.  The only real viable solution is more power.  Lots more power.

I'm at a slight advantage with TPI anyway.  3500 is a pretty low RPM to really begin to make power.  An LT1, or worse yet, and LS1 with a really peaky powerband (5,000 RPM's plus) only has a a larger task to overcome.  In a typical LS1 M6, 5,000 RPMS in first gear is nearly 40 MPH!  Now you have to catapault a 3600lb car to almost 40 MPH.  God help you if you drive a 12,000 RPM 4 banger.  I can attest to this theory with my own experience.  My older corvette was an LT1 based 383 stroker.  My current car gives up over 100 RWHP, and about 50 RWTQ to the stroker.  The 60 foot times are almost identical.  While the stroker was much faster in the 1/4 mile, the RPM's had to be significantly higher than 3500 for it to really start to make power.  Hence the difficulty in launching it effectively with a tire that dead hooks.

Thoughts?
« Last Edit: August 27, 2005, 02:32:27 pm by neat »

Offline GeoffWhite

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Re: How the heck do I make my car 60' worth a darn
« Reply #6 on: August 27, 2005, 03:22:52 pm »
Have you ever ran on street tires or something that dosn't dead hook? You could use your tires like a stall converter and get just the right ammount of tire to let them slip enough to get you into the powerband. You don't really have to worry much about wasting the tires since you don't really spin the motor past 4500. Also I don't know if you can change first gear in your car to a lower ratio gear or not? Maby putting in a lower ratio first gear in the tranny would help. I'm sure there is someone that can machine one if you can't buy one.
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neat

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Re: How the heck do I make my car 60' worth a darn
« Reply #7 on: August 27, 2005, 07:51:16 pm »
I have tried a bunch of street tires.  I lack the finesse to get them to 60 for anything.  2.0-2.1 is the best I can manage with street tires on the IRS vette.  With my old WS6, my best was a 2.2.

Trying several different kinds of tire to see which ones spin into the power band is a good idea, except that I can't afford to try 3 or 4 set's of tires.

Altering 1st gear ratio is also a good idea I think.  Just not real practical for me right now.

Maybe I'll try overinflating the streets and see what happens.

Offline The Sad

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Re: How the heck do I make my car 60' worth a darn
« Reply #8 on: August 27, 2005, 11:39:18 pm »
My theory behind my shock suggestion stems a little from what I think my car it doing.  On the slicks, it feels like it hooks right out of the hole, so how can I 60 like crap?  I got a video, and think that I weight transfer on launch, hook, then 10 or so ft out the suspension transfers weight the other way and unloads the rear tires, allowing them to spin for a bit.  Vettes are not known for their drag suspensions, so I imagine the effect would be worse.

Just my theory on it all.  Do you have a video of yours you can study?

The SS looks like it could kick your ass, the WS6 looks like it's coming over to do it!

99 Trans Am WS6 - a few mods ;)
06 YAMAHA Raptor
06 YAMAHA R1
01 Honda CBR F4i - track bike
05 Dodge Ram 2500

neat

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Re: How the heck do I make my car 60' worth a darn
« Reply #9 on: August 28, 2005, 03:09:45 pm »
A guy named Jeb Burnett on the corvette forum told me there was no way I was dead hooking the tires.  Normally I would dismiss it as someone who doesn't know anything is talking out their ass, but he has probably the fastest M6 C4 in the country.

I swear the tires are hooking, zero wheelspin.  I guess video is the next step, to see what's actually going on.  Maybe what Jeb meant is what you're talking about, wheelspin after the launch.  My car makes less than 400 RWHP though so wouldn't think that's it.  Hell, it won't break street tires loose from a roll in first, I can't imagine it would do it with slicks.

Keep em' coming guys!

Goody_Seven

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Re: How the heck do I make my car 60' worth a darn
« Reply #10 on: August 28, 2005, 06:34:42 pm »
Are you shifting to second before the 60'?

Offline gofast

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Re: How the heck do I make my car 60' worth a darn
« Reply #11 on: August 28, 2005, 09:22:45 pm »
I am dead hooking the tires I have now.  I have all the traction I need.  When I drop the clutch, the car lurches forward, and the motor almost instantly bogs.  This results in 1.8XX times.

The reason I quoted you above, is the bog. If you are bogging after you launch, it's very likely you are simply not making enough power to move the weight. A gear set would be the best alternative. Beyond that, you're right, you'll need more power. I don't think this is the issue though. According to the numbers you quoted as having, you have enough power.

There are a few other minor things that do play a part, but I won't go into them much - Track Temp- Real hot or cold can hurt. I think around 95-100 degree's is best for my car. More than 115 or a cool day, you'll have problems. Your burnout- If you are getting your tires too warm or cold, you won't hook either. Tire pressure. Too much will make your tires bubble out and not enough will make them cup. Not knowing what size tire you have or kind (Drag Radial or real slick), I don't know where to suggest.

You need to put a white stripe on your tires and video tape it. Watch it in slow motion, are the tires really hooking? The white stripe is there to be able to really see what your tires are doing.  Maybe, maybe not. I know what you are saying by them feeling like they are hooking, but they can feel that way and actually be spinning. My car feels like it hooks, but if you watch the video, even of my avatar, you can see the tire spinning.

Here's a video of my car (maybe not a good example), http://www.jbmotorsports.com/movies/jeremy10.wmv but you can see the stripe on the rear of the tire between the Hoosier logo's before my burnout. When you video tape the car, have someone come up as close to the side of your car as you can get away with. Sometimes they'll give you a hard time at the line, but don't get in front of the car. Get to the side and video tape the car. You'll be able to see in slow motion the strip move around as you launch.

Lastly, because I've been having my own traction issues over the last year, I spent some time researching certain launch techniques and setups. Because I'm limited on tire size and am assuming you are too, I looked at Stock Elimator cars to see what makes them hook so well. The best thing I could come up with was the width of my rear wheel. It actually makes a difference. I was running a 10" wide slick with an 8" wide wheel. What that was doing was making the sidewall softer than it needed to be. This year, I forked out the change and bought two 10" wide wheels and dropped a little over a .010 of a second on my sixty's with essentially the same size tire. All or most of the Stock Eliminator cars are running as wide a wheel or even an inch wider wheel than their slick width. This makes the sidewall stiffer and transfers more power into forward motion instead of spinning or pressing the tires to the ground. I will say this has been the single best improvement in my 60 foot times this year. Tubes in your slicks will also make the sidewall stiffer, this could be another suggestion.

I think you are probably feeling like you are hooking, but it's spinning a little. Remember, this is RMR and my car hooks substantially different at other tracks. I know others on here will attest to this. Video tape the car and let us know. I bet you are making enough power, just getting it to the ground is the key.
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neat

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Re: How the heck do I make my car 60' worth a darn
« Reply #12 on: August 29, 2005, 09:06:44 am »
Are you shifting to second before the 60'?

I don't think so.  Thye car will go about 40 MPH before I shift out of first.  It's got the stock 3.45 gears in it now.

As far as power, it's stock L98 with a 100 shot.  I don't spray until after the 60' mark though.  The car only makes 250 RWHP/350 RWTQ NA, so maybe I'm not making the power to move the car.

I am running in North Carolina, not RMR, so the track temp is almost always above 110.  Prep is pretty good most of the time.

I'm running a 26.5x10.50x16 ET street on an 8 inch wheel.  14 PSI, no burnout, just a dry hop infront of the waterbox.  I don't have a linelock, and the car doesn't really make the power to get them to smoke without one.  Like I said, I am pretty sure I have all the traction I need.

I'm gonna video the car this weekend, maybe I am spinning a little.  If I thought the clutch would take it, I'd spray off the line.  If I'm not spinning and still cutting crappy times, maybe I'll give that a shot.
« Last Edit: August 29, 2005, 03:35:42 pm by DaBo_Z28 »

Goody_Seven

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Re: How the heck do I make my car 60' worth a darn
« Reply #13 on: August 29, 2005, 11:25:43 pm »
I have found that the 60' marker is a lot farther than I thought.  When I first put in 4.10s my car felt like it came out of the whole harder, but my 60's didn't show that, I later found that I was shifting before the 60' box which hurt my time.  When I was able to rev higher my 60' went down .10 without anything else changing.  What is your 330'?  On a 1.8 60' I average around 5 flat to the 330'.  What I am getting at is maybe your car hooks good and you just shift like an old lady??

neat

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Re: How the heck do I make my car 60' worth a darn
« Reply #14 on: August 31, 2005, 04:07:38 pm »
330 is high 5's.  5.9 or so.

I'm an average driver at best, and the vette has a huge throw (like 8 inches) from first to second.  I'm going to get a shifter as soon as finances allow.  I just need a windsheild and a place to live first.  Maybe a clutch, another set of slicks, draglites, etc...  The list never ends.