RX794

Got a question for everyone. Since we're talking IRS records here, who's got the record for the quickest FD with independent rear suspension AND a stock Mazda manual 5 speed transmission case? Please specify with or without the internals of the case being changed(ie: dogbox). Anyone got that answer?

Jay7 Nyc

iTrader: (3)

My guess would be the guys from the UK, using the RX8 trans...

RX794

Sorry if I didn't specify my question. I meant an who's got the record for the quickest FD with independent rear suspension AND a stock Mazda FD manual 5 speed transmission case? Please specify with or without the internals of the case being changed(ie: dogbox). Does anyone have that answer in detail with specific ET and MPH?

ErnieT

iTrader: (2)

I should take that down. I've got a hell of a long way before I get close to a 8 sec pass! lol...

ari

How fast are they going on the rx8 gear box?

zinx

iTrader: (3)

Pretty quick.

https://www.rx7club.com/showthread.p...&highlight=rx8

ari

that picture looks awesome!!!

9.61 is good but I figured that someone would get closer to 9.0 by now...

here's a 9.62 video from 3/12/2000 yes... 8 years ago. Running a 13B, mazda 5sp (stock internals) and all original glass through the muffler.


http://www.youtube.com/watch?v=CtzF04OThtI


come on guys... Ernie... Lee... step it up

... just teasing.

keep up the efforts and let's get a mazda tranny car in to the 8.99 range... I think it can be done!

AnthonyNYC

iTrader: (3)

Take a look at this video of Ari in 2007. Ari, what tranny was in the car at that point? Also, what was the time on that run?

http://www.youtube.com/watch?v=ULyYK0VgbCA

Thanks,

Anthony

4rotores

hey anthony i guess we all are goin for a new record. cause i'm goin to ry to bring mines down to what ever i can with my setup.

4rotores

AIN'T AS EASY AS EVERYONE THINKS! For all the keyboard warriors that would rather type in " YOu have 700+hp, running 9's should be a cake walk"......Go spend the money, build your car and run 9's. Till then, zip it! lol....


i agree 100% with that people think that is easy just make power and thats it you running 10's or 9's. but the money we spend doin this is all lost money. i have been thru 2rotor 3rotor and when i had my 3rotor i had the power but there were alot of little things to get done so the car could run good munbers. KEEP IT UP DON'T GIVE UP YOU WILL BE THERE SOON. as for me i'm looking for high 8's yea right.

Crash Test Joey

iTrader: (1)

+1 (+ a bunch of others who agree)

Put your front on full loose and the rear on full tight, to start with. When you push down on the rear of the car, you don't want it to drop, you want it stiff. Start around 11 psi in your rear tires and 45 psi in your front tires. Check and reset your pressure if necessary before every single run. Get someone that's good with a video camera to shoot your car off the line, focusing on the rear tires to see what they are doing when you leave. Knowing how much you're spinning is a huge help.

Do you have a two-step? Because if you don't, you need one. Set the launch for something below your powerband, probably in the 3500 rpm range. I'd have to see your current dyno graph to get a better idea, but basically a two-step will allow you to sidestep the clutch without overpowering your tires or bogging down in first gear. A few test passes should tell you what to launch at.

Let me know if you have any questions about why I listed this stuff.

Crash Test Joey

iTrader: (1)

There are MANY cars running 8's on drag radials, there's really no reason an ET Street shouldn't do just fine. I personally know of an 8-second @150mph car weighing 3600lbs that runs them and doesn't have a problem with the tires at all.

ari

Crash Test, I don't get on the forum as often as I should but I'm trying to make it more of a habit for myself. I'm sorry if I'm not showing proper forum manners but I'm really interested in drag racing and especially drag racing IRS.

In my experience, drag racing an FD is a balance of making power and making the car hook hard enough to launch but not so hard that parts break. With the most important part being... not break!

I don't understand why the combination of rear-full hard, front-full soft, 11 psi in drive tires and a launch RPM of 3500 would work well.

4rotores

hey ari when you ran 9.1 what tranny did you have?

61620B

G-Force and NOS energy drink.

Crash Test Joey

iTrader: (1)

I don't know that the combination as it's listed would work well, but it's a starting point. I'm sure you have more knowledge of IRS racing than I do, my racing has all been done with solid-rear cars. But the theory isn't too much different.

For the rear, it's pretty obvious that the rear of the car squats enough in stock form, and you can drop the rear down to the stops and you're still not picking the front tires up (weight isn't really transferring well) so you need to stiffen it up. The car doesn't need to squat onto the bumper to hook. Full stiff may be too much, but going loose in the rear just gives the rear a place to go when the power comes in, instead of moving the car forward. All that squatting is just wasting energy and putting flex into something that doesn't need it.

In the front, you don't want full stiff for the same (but opposite) reason: you need weight transfer. If your springs are tight, the front end is going to sit where it is. You want it to come up. If your front tires are in the air, or the suspension is at least unloaded, then all the weight is on the rear, and that will equal traction when you find the right rear suspension settings. Think about all the motorcycle drag racing guys who strap their stock front ends down. They do it to STOP the bike from doing a wheelie. They WANT their bikes to stay down and spin the rear tire, because if they wheelie they'll lose a lot of time or loop the bike. No IRS-rear RX7 is in danger of flipping over backward, so we'll take all the upward movement of the front end that we can get.

11psi is just a basic starting point for the rear tires. Drag radials have been known to work down in the 13-14psi range, and ET Streets are more or less ET Drags with a couple grooves in them. On my Mustang I had success around 11-12psi, but never more than 12.25psi. I wouldn't go below 11 or higher than 13, and every track and track/condition calls for different settings, but it's a place to start. Trying to work your way down from 13 wouldn't be a bad idea.

For the launch RPM, a two-step is really the only way I have used to have a consistent launch rpm. My supercharged Mustang had roughly 600rwhp when it put down a couple 9.8x passes, with the power coming in around 4k and peaking about 5900, dropping off drastically at 6300. I normally launched at around 5500 on the two-step, shifting at WOT (our transmissions are pro-shifted) at around 6500. During the shift RPM would peak about 7100 and drop to 5200 or so when the clutch came back out, so it would still be in the powerband. The big difference between the cars is the rear in my car would hook and pull the front tires in the air, something that's not easy to do on an IRS car, so it takes more testing to figure out where to launch.

I said 3500 for Ernie because I was guessing at the powerband. He is consistently blowing the tires away so he needs to be well below his peak power when he lets the clutch out on the line, not just a little below it or just slightly out of boost. The rpm needs to be low enough that he can just hook and go, but high enough that the car doesn't totally fall on it's face. That rpm may actually be around 2500, or as high as 5k for all I know, without looking at his dyno graph. If a few hits are made and the car is "just barely: falling on it's face, adding a .25-.5 lb of air pressure to the tires can create enough spin to bring it into the power faster without blowing the tires off.

As to your other point about parts not breaking, well, if you're not breaking things then you're not going fast enough, right? The key thing to do in this situation is test, test, test again and then test some more. There are only so many links between the driver's right foot and the track. If you make slight changes to each of those things, eventually you'll find something that works. And then the following week the track will be different and you'll have to start over

enzo250

Just to clear up the suspension talk...

In drag racing you want to get good transfer in the rear so you get good grip..
You also don't want to unload that grip once you get it...

The way you should setup you car is so the front end will raise easily but come down very slow. You can do this with double adjustable shocks or custom valved shocks with adj rebound. You basically want very little rebound with alot of compression. So it's easy for the shock to go up BUT very hard to come back down. (this will help prevent the tires from unloading)

The Rear is the opposite. You want to squat the rear and stay there. The way you do this is with very soft compression and alot of rebound. Again a double adjustable shock is recommended. You want to be able to compress the shock with ease but it should be very slow to come back.

I have developed a killer suspension setup for my FC(some members here have seen it) but have yet to test it out since my project is dragging along slowly..

Might have to do the same with an FD since my brothers car is running and needs to get it to the track...

enzo250

If you launch ernies car at 3500 it will flat out fall on it's face..

He's blowing his tires away because he has too much power for his suspension setup. He needs to lower the power and bring it in later on and/or get better suspension.

enzo250

Ernie,

I just watched all of your video's and i can see exactly what's going on.. Well one of the video's doesn't show the rear tires but you can hear what happens just like the other 3 video's..

It looks like you have some sort of road race coilover setup. What's happening is your planting the rear tires but there instantly unloading. This is typical of have road race suspension works. Once you compress them they instantly come back. This is no good. Your instantly blowing the tires away...

Thats what you want it a road race car, so keep that suspension for that purpose but it's NO GOOD when drag racing. You need to get suspension or at least put back the stock shocks... You will see a world of difference..

I'm not sure if it will help you get the title of fastest IRS car though as that record is coming to NY... LOL..

Crash Test Joey

iTrader: (1)

He's got 32 way adjustable shocks on the car, his suspension isn't going to get any better without going to a solid rear. Maybe you missed the part where I said 3500 was a starting point and he needs to test different launch rpms

F1blueRx7

iTrader: (5)

He's talking about the rebound/compression settings being adjustable. They could just have 32 stiffness adjustments that collectively control both compression and rebound at a linear rate.

He needs something like a QA-1 which are available in double adjustable configuration. I don't know who makes that for an RX, maybe HKS drag coilovers?

edit: I'm not a drag racer, but I understand enzo's theory and recall how much rebound ernie gets when shifting compared to successful drag cars

Busted7

Well its all cleared up now! Ernie just start over.

Crash Test Joey

iTrader: (1)

I knew what he meant, but I assumed with the amount of resources Ernie has put into the car he already had that type on the car. I had 4-way adjustables on my car and the car did wheelies (though I would have preferred the Qa1's, I just never got around to it). So I would assume Ernie can come up with something that will work if he tests more things than just the anti-lag settings...

enzo250

Thank you.. At least some people understand....

HKS makes drag coilover kits but there not worth the money and not double adj...
For that kind of money you can build a killer setup..

QA1 doesn't make anything for RX-7's BUT i've used other applications and made modifications to make them work on RX-7's. I got full adjustable QA1's on my car now.

ari

I don't remember the ET on that pass, that weekend I ran mostly 9.7-10.1 passes. The competition was soft and the track wasn't so good...