Alright, so my 603 whp RX7 needs help.
#26
Originally Posted by LUPE
Thanks for your advise Cris.
My ET Fronts say max tire pressue 35 psi I think, should I still crank them up to 40-50 psi ?
Can I run 7psi because the car is so light? I've never heard of anyone running that low of pressure. Dan Schechter says he runs 12-15 psi and he's cutting 1.3X 60 foots so I don't understand why I'm having problem hooking up.
Should I just soften the fronts and rears all the way and see how that feels?
And people say drag racing is easy
My ET Fronts say max tire pressue 35 psi I think, should I still crank them up to 40-50 psi ?
Can I run 7psi because the car is so light? I've never heard of anyone running that low of pressure. Dan Schechter says he runs 12-15 psi and he's cutting 1.3X 60 foots so I don't understand why I'm having problem hooking up.
Should I just soften the fronts and rears all the way and see how that feels?
And people say drag racing is easy
Your car has a solid rear. Dan's still running the IRS so he have to adjust to suit
although I have also ran as low as 8psi when I was still running the IRS to compensate for a bad track.
You're not taking advantage of what you have. A solid rear with 4-link.
#27
forgot to add this, not sure if youve seen it but it may help.
http://www.afcoracing.com/tech_pages/4link.shtml
http://www.afcoracing.com/tech_pages/4link.shtml
#28
Rotary Freak
Joined: Jan 2002
Posts: 1,640
Likes: 0
From: l.a.
activate the 2-step so you build some boost off the line while also mitigating your boost ramp in 1st and 2nd gear. your problem is not that you make too much power off the line, it's that the power is ramping up too quickly which is causing you to blow away the tires. you'd be better served with more baseline power at the launch and less slope on your boost gain. although you'll be launching with more power, a nice stable rise in power will help you hook much better than launching with no boost and an exponential rise in power. you can control wheel speed by fine tuning the rate of boost ramp w/ your boost controller. you're basically just trying to tune your power curve to get a good balance that allows you to get up on the tire without creating excessive wheel spin. work on fine tuning your wheel speed first before you start tuning the 4-link and you'll be fine. ideally you'd want a slider clutch to control your wheel speed, but in your case you'll have to do it with boost control.
Last edited by fdracer; 09-21-06 at 02:10 PM.
#29
Originally Posted by fdracer
activate the 2-step so you build some boost off the line while also mitigating your boost ramp in 1st and 2nd gear. your problem is not that you make too much power off the line, it's that the power is ramping up too quickly which is causing you to blow away the tires. you'd be better served with more baseline power at the launch and less slope on your boost gain. although you'll be launching with more power, a nice stable rise in power will help you hook much better than launching with no boost and an exponential rise in power. you can control wheel speed by fine tuning the rate of boost ramp w/ your boost controller. you're basically just trying to tune your power curve to get a good balance that allows you to get up on the tire without creating excessive wheel spin. work on fine tuning your wheel speed first before you start tuning the 4-link and you'll be fine. ideally you'd want a slider clutch to control your wheel speed, but in your case you'll have to do it with boost control.
Andrew
#30
Originally Posted by fdracer
activate the 2-step so you build some boost off the line while also mitigating your boost ramp in 1st and 2nd gear. your problem is not that you make too much power off the line, it's that the power is ramping up too quickly which is causing you to blow away the tires. you'd be better served with more baseline power at the launch and less slope on your boost gain. although you'll be launching with more power, a nice stable rise in power will help you hook much better than launching with no boost and an exponential rise in power. you can control wheel speed by fine tuning the rate of boost ramp w/ your boost controller. you're basically just trying to tune your power curve to get a good balance that allows you to get up on the tire without creating excessive wheel spin. work on fine tuning your wheel speed first before you start tuning the 4-link and you'll be fine. ideally you'd want a slider clutch to control your wheel speed, but in your case you'll have to do it with boost control.
I'll try softening the shocks and lowering the tire pressure a bunch and see what that does. I might turn the 2 step on and try out a 6K pill instead of the previous 8K pill.
#31
Originally Posted by andrewb70
The above advice seems very good. The only other thing that I can think of is that you are loosing time on the shifts.
Andrew
Andrew
#33
Originally Posted by 13B-RX3
When do you plan on going to the track again?
#35
Originally Posted by iceman4357
why not buy an electronic boost controller if that will get you to your goal?
#36
If you have not done any setup on the 4-link besides aligning it you might consider changing your instant centers. There is no reason you shouldn't be able to get that setup to hook so hard that it snaps the trans .
#37
Originally Posted by 13B-RX3
If you have not done any setup on the 4-link besides aligning it you might consider changing your instant centers. There is no reason you shouldn't be able to get that setup to hook so hard that it snaps the trans .
#38
It is almost impossible to set the instant centers and anti squat characteristics without making a pass in the car. There are too many variables that are not measurable IE track condition, tire grip, power delivery. First i would recommend having someone who knows what they are doing set the car up at the track you plan on running.
If you want to play with it a little to see what effect it has try shifting the IC toward the rear of the car a bit.
Does the car seem to squat excessively or raise the rear when you launch it?
If you want to play with it a little to see what effect it has try shifting the IC toward the rear of the car a bit.
Does the car seem to squat excessively or raise the rear when you launch it?
#39
Originally Posted by 13B-RX3
It is almost impossible to set the instant centers and anti squat characteristics without making a pass in the car. There are too many variables that are not measurable IE track condition, tire grip, power delivery. First i would recommend having someone who knows what they are doing set the car up at the track you plan on running.
If you want to play with it a little to see what effect it has try shifting the IC toward the rear of the car a bit.
Does the car seem to squat excessively or raise the rear when you launch it?
If you want to play with it a little to see what effect it has try shifting the IC toward the rear of the car a bit.
Does the car seem to squat excessively or raise the rear when you launch it?
Actually, I just talked to the person who set it up originally. He actually set it up at the track a few years back ( I completely forgot that he did that ). He said that the pinion angle is 2 degrees down and instant center is 70 inches out / 20 inches up. That's just the info I got off the phone with him. He said everything should be fine.
He pointed out that if you watch the videos, you can see that there is no weight transfer at all. The front end doesn't come up hardly at all.
My shocks have a valve system that allows simultaneous rebound and compression damping adjustment. I have this set on the stiffest possible so it won't allow my front end up to come up at all. The rear shocks are set to the stiffest also so they won't hardly compress.
What do you think?
#41
Originally Posted by razorback
dont you want some weight to transfer to the rear to help with traction?
You can see in my videos that I have no weight transfer at all. I've been running the stiffest settings front and back for years now.
#43
Eric: i would soften the front up totally and soften the rear up by half and see how it likes that. Other than that try the 2step at what you said so you can build some boost and just go from there with the tuning process. I would start out at 10-11psi in the rears and adjust accordingly. If you still can't find traction then lower the 2step pill and try again. Are you sidestepping the clutch or riding it out? Obviously riding it out would be the best choice.
The fronts i would take up to at least 35-40psi. I haven't had any experience with any higher like Chris said but if it works then give it a shot. Less rolling resistance means it should go quicker and faster.
What kind of boost can you build with the 6k pill in? As long as you can build some boost and not bog too bad you should get a clean pass in....which is the ultimate goal right. Get a clean pass with a good backup and then start the tuning.
Also what FDracer said is pretty damn good advice! It sure sounds like he knows how to tune!! Kinda sounds like a Mustang racer. That's exactly what those guys have to do.
The fronts i would take up to at least 35-40psi. I haven't had any experience with any higher like Chris said but if it works then give it a shot. Less rolling resistance means it should go quicker and faster.
What kind of boost can you build with the 6k pill in? As long as you can build some boost and not bog too bad you should get a clean pass in....which is the ultimate goal right. Get a clean pass with a good backup and then start the tuning.
Also what FDracer said is pretty damn good advice! It sure sounds like he knows how to tune!! Kinda sounds like a Mustang racer. That's exactly what those guys have to do.
#45
I very fast local turbo mustang guy just told me this. What do you guys think?
On a street car with small tires your pinion angle (2) is to high, set it at 4-5. Loosen the front all the way up loosen the back one maybe two. As light as the car is, you need to drop the tire pressure down around 6psi. Make sure the wheels are screwed to the tires or they will spin. I run Et streets and I was running 5.5 lbs last tuesday also. You need to do your burn out in one spot then roll forward if you do a big prostock style the tires will not heat up and the track will suck the heat right out of them. ET Streets are very picky about pressure and temps. When it's hot, they like 12-13 psi but when it gets cold, they need less pressure
#46
Rotary Freak
Joined: Jan 2002
Posts: 1,640
Likes: 0
From: l.a.
Originally Posted by LUPE
You can see in my videos that I have no weight transfer at all. I've been running the stiffest settings front and back for years now.
#47
Originally Posted by fdracer
the reason you don't have any weight transfer, like i said before, is you don't launch w/ enough power. most people assume that if they're breaking the tires loose they have too much power off the line, when in fact the converse is often true. you need that extra power to pick up the front end and get the rear to squat. try 2-stepping it and see where it goes. don't worry too much about shock settings right now; soften them up a little but there's no need to do too much fine tuning at this point.
#48
Eric: the Mustang guy does sound like he knows what he's talking about except for the tire pressure. I can't see someone recommending that low of a psi. I would think that kind of setting might be for a seasoned racer. You're still getting to know the car so try and take baby steps. Get some clean passes in and get consistant before trying crazy things. That way you'll know exactly what hurt or helped.
Also, does your car bounce at all in the rear?
Also, does your car bounce at all in the rear?
#49
Originally Posted by silvr94r2
Eric: the Mustang guy does sound like he knows what he's talking about except for the tire pressure. I can't see someone recommending that low of a psi. I would think that kind of setting might be for a seasoned racer. You're still getting to know the car so try and take baby steps. Get some clean passes in and get consistant before trying crazy things. That way you'll know exactly what hurt or helped.
Also, does your car bounce at all in the rear?
Also, does your car bounce at all in the rear?
#50
Put your rear shocks on full soft, your fronts on full hard. You want squat.
And running 6 PSI on ET Streets seems nuts to me. Consider putting tubes in them if you are going to try it. I would stick at 11 or 12 lbs.
And running 6 PSI on ET Streets seems nuts to me. Consider putting tubes in them if you are going to try it. I would stick at 11 or 12 lbs.