'89 Daytona C/S NHRA Stocker

[BadAssPerformance]

Cool... fix that pitch. I currently have 600 #/in front and 1000 #/in rear and it no longer squats

[ShelGame]

Cool... fix that pitch. I currently have 600 #/in front and 1000 #/in rear and it no longer squats

I'm actually somewhat if the opposite position. I want to let the car move, I just want to make sure the wheels are still pointing the right way when it is in the launch position.

Its a transient weight transfer thing. If the car is infinitely stiff, the weight transfer occurs instantly when the acceleration is applied. But, if the car is allowed to move a little, then you don't unload the front tires as quickly. And, hopefully get a little better traction on launch.

Of course, there's a balance. Too much movement and you lose traction due to toe or camber changes.

I'd prefer to have the suspension soft, and control the movement with a wheelie bar.

[Ondonti]

I'm actually somewhat if the opposite position. I want to let the car move, I just want to make sure the wheels are still pointing the right way when it is in the launch position.

Its a transient weight transfer thing. If the car is infinitely stiff, the weight transfer occurs instantly when the acceleration us applied. But, if the car is allowed to move a little, then you font unload the front tires as quickly. And, hopefully get a little better traction on launch.

Of course, there's a balance. Too much movement and you lose traction due to toe or camber changes.

I'd prefer to have the suspension soft, and control the movement with a wheelie bar.

I am thinking the opposite, that the softer launch would be better on parts but I don't see 60' improvement from that movement. Rear Traction bars are used on FWD cars for a reason, they work.

I also never got to get a limiting strap setup worked out on my rear end (fake having very stiff springs) where I would preload the rear end air shocks instead of letting the rear end keep jacking up. I think that would have eliminated the little front end lift that I have.

As to reaper's point, this car is never going to make enough hp to need help on the top end and its over slicked to get everything possible on the launch.

BTW have you considered a 25x9 slicks on 13" rims instead of this giant setup. Small oem brakes etc. I guess you are already invested in this path :P At some point you are going to have to invest in keeping your slicks replaced to keep them fresh. You have a history of running them to the point where they are hurting your times. For me it would not matter but you are trying to max out your potential every run. With 26's I don't really know if you would ever have traction problems even when they get old. It might just be that you lose consistency.

[85boostbox]

I don't think rob is going for fastest time. More or less consistency. I couldb be wrong though...

[ShelGame]

I am thinking the opposite, that the softer launch would be better on parts but I don't see 60' improvement from that movement. Rear Traction bars are used on FWD cars for a reason, they work.

I also never got to get a limiting strap setup worked out on my rear end (fake having very stiff springs) where I would preload the rear end air shocks instead of letting the rear end keep jacking up. I think that would have eliminated the little front end lift that I have.

As to reaper's point, this car is never going to make enough hp to need help on the top end and its over slicked to get everything possible on the launch.

BTW have you considered a 25x9 slicks on 13" rims instead of this giant setup. Small oem brakes etc. I guess you are already invested in this path :P At some point you are going to have to invest in keeping your slicks replaced to keep them fresh. You have a history of running them to the point where they are hurting your times. For me it would not matter but you are trying to max out your potential every run. With 26's I don't really know if you would ever have traction problems even when they get old. It might just be that you lose consistency.

Yeah, I know you know everything about tires . FWIW, in the 7 years I ran the 22's, my 60' times never really changed. If anything, they improved as the car got better.

I took ~0.08 off the 60' times when I put these tires on last year. I'm not running 26's, BTW. They're M&H 24.5x8.5. And, they're used.

Everyone in NHRA tells me I'm wrong, too. All the other FWD cars run super stiff springs, and super stiff shocks; with the a$$ end up in air and front way down low with tiny little slicks. They get 1.9 short times and I get 1.7's. But I'm doing it wrong. My 60' times are similar to other 'slow' RWD stockers. So, I think I'm doing pretty good.

I can't run a 13" wheel. 14" is the smallest allowed in stock by the rules. Tim Kish runs 13's on the front of his Neon, but that's super stock. Pretty much anything goes in the class he's in (except for boost).

- - - Updated - - -

I don't think rob is going for fastest time. More or less consistency. I couldb be wrong though...

No, I want to go fast, too But, I also want the car to be 'dial-able'; it's starting to get there...

[Reaper1]

The tiny little slicks is their problem. They probably do it because they don't have the torque you have, though.

Super stiff is just as bad as super soft. There has to be SOME give. I'd want to limit that motion, or slow it down as much as possible, though.

The other thing to consider is the automatic transmission. The power delivery is more stable down the track, so once the car takes a set, it doesn't move around like a manual car will. That said, I'd think that having a moderate bump and fairly stiff rebound control with moderate springs on the rear and harder springs up front with soft rebound and stiffer bump might work. The reason I think that is because in my mind I'm envisioning the car transitioning and then staying in the same position during acceleration.

The rear will let the car squat, but in a very controlled manner. The front will let the suspension droop and the springs will help keep the tires down. Add in some sort of progressive limiting strap so the front can't rise too much and I think it might be money.

[Ondonti]

I would assume very very very few competitors are running FWD and automatic transmission. The hondas that re built and driven well will 60' much better then those numbers mentioned.
I also don't really think you were overpowering 22" slicks since I have seen 120+mph cars run old 22" slicks so mentions of consistency would reflect more on cars that are near the limit of their tire. Of course those 120mph cars would not be able to pull off a 1.7 60' with manual transmission. I have run on sets of the same size/brand slick, one 8 years old (and patched and not treated well etc), one 1 year old. Huge difference. I would almost prefer the older slick because breaking stuff sucks. Automatic is also not such a problem there if you avoid wheelhop.

[ShelGame]

I would assume very very very few competitors are running FWD and automatic transmission. The hondas that re built and driven well will 60' much better then those numbers mentioned.
I also don't really think you were overpowering 22" slicks since I have seen 120+mph cars run old 22" slicks so mentions of consistency would reflect more on cars that are near the limit of their tire. Of course those 120mph cars would not be able to pull off a 1.7 60' with manual transmission. I have run on sets of the same size/brand slick, one 8 years old (and patched and not treated well etc), one 1 year old. Huge difference. I would almost prefer the older slick because breaking stuff sucks. Automatic is also not such a problem there if you avoid wheelhop.

In sport compact, maybe there aren't too many autos. But in NHRA stock, almost all FWD cars are auto. I actually can't think of a single manual trans FWD car currently running.

I don't think I was overpowering the 22's either. I think that the taller 24.5" sidewall is more 'forgiving' - it is softer torsionally than the 22's. So, when the torque hits, it absorbs some of the shock and keeps the contact patch adhered. I actually would have preferred to run 24.5's with my old 14" Centerlines. But, 14" tires are getting really hard to find. Only M&H still makes them, and I think all they have is the 23" slick. Which actually doesn't really have any more sidewall height than the 24.5 x 15's.

I've actually never had a problem with wheelhop or breaking parts. That's definitely one of the advantages of running an auto.



And so, on to my Test-n-Tune results:

Went to the track (Milan Dragway) today to get some testing in with the new wheel/suspension/tire and my T/SMEC 2-step. The results were, well, maybe not quite disappointing but not as good as I had hoped. Mostly I was working on getting the 2-step to work the way I wanted. I only got 3 passes in (they were bracket racing, too). So, I didn't get time to try a couple of things that I want to try. But, basically, the 2-step allows me to leave with MUCH more throttle than I was previously.

Before, too much throttle and RPM would overpower the front brakes and creep the car forward and usually make me go red.

With the 2-step, I can give it more throttle and still hold it. The problem is, when I release the brakes, the turbo spools near instantly and the tires just spin for 30' (it feels like). I tried softening the launch by lower the launch RPM and reducing the anti-lag and enrichment values. But, it didn't help much. I have a min TPS threshold for the 2-step to activate, and I think maybe that could be set lower. But, I also need to think of other ways to soften the launch.

I wish I had setup MP Scan to log these runs (DOH!). I'd really like to know what the boost was doing on launch.

GoPro videos are uploading now...

[bakes]

you can try and set the 2 step off at X mph

[ShelGame]

you can try and set the 2 step off at X mph

It's actually required by the rules to turn off with the brake pedal...

[Force Fed Mopar]

Mine builds about 6psi of boost on a stock Garrett w/ the 2-step set at 3500. Haven't checked to see what it builds now that I have it set at 4k.

[ShelGame]

TnT Videos...

[Vigo]

Im kind of shocked that you're spinning the slicks launching from <3000 rpm. How much boost is it building the way you have it set? Do you think being under the stall rpm of the converter actually makes it harder to launch due to torque multiplication? If that were the case i would think getting it to stay against the stall but making less boost would be easier to hook.

[ShelGame]

Im kind of shocked that you're spinning the slicks launching from <3000 rpm. How much boost is it building the way you have it set? Do you think being under the stall rpm of the converter actually makes it harder to launch due to torque multiplication? If that were the case i would think getting it to stay against the stall but making less boost would be easier to hook.

Hmm, maybe.

I was considering how to make a 'decay' function so that the staging limiter stays on for a couple of seconds after the brake is released (while moving) to kind of soften the hit.

[gasketmaster]

Try shifting the 1-2 early and see what happens. If it helps you will see it in the 60'. Also, get some video from outside the car to confirm tire spin.

[ShelGame]

Try shifting the 1-2 early and see what happens. If it helps you will see it in the 60'. Also, get some video from outside the car to confirm tire spin.

Shifting 1-2 early will be tough. It comes up on me too quick as it is; I'm usually late...

[Captain Chaos]

In sport compact, maybe there aren't too many autos. But in NHRA stock, almost all FWD cars are auto. I actually can't think of a single manual trans FWD car currently running.

Chuck strictly running the PT convertible and not the SRT-4?

[Ondonti]

Well if you are trying to be more bracketish and consistent, I think you need to do this at complete WOT and then drop your 2 step rpm until you bog then work back up...keeping track of 60's the entire time.

That mitsu turbo and antilag is not your friend. I see you basically jump to 5000 rpms in both videos and your car seemed a lot happier when it finally hooked up. They say that whole "20% wheelspin is ideal" thing but being 5000 rpms all the way means you are a lot more then 20% at first. Not sure if want much of any spin on an Auto that doesn't break parts or have bogging problems.

I was going to suggest removing timing at lower rpms to decrease power in the 2000-4500 rpms range (which you didn't seem to use at all even with a mitsu) after "maximising" your launch rpm and avoiding bogging. That will keep your turbo spooled up but decrease power and increase traction. Lots of fiddling to get that all right. Lots of test passes. You could probably keep a higher launch rpm go WOT, and then remove so much timing that it bogs and then add healthy amounts back in until it starts spinning "too hard" again.

[ShelGame]

Well if you are trying to be more bracketish and consistent, I think you need to do this at complete WOT and then drop your 2 step rpm until you bog then work back up...keeping track of 60's the entire time.

That's not a bad plan. Though, I'm launching at 2k now, and no bog to be seen. I guess 1800 is the next step...

That mitsu turbo and antilag is not your friend. I see you basically jump to 5000 rpms in both videos and your car seemed a lot happier when it finally hooked up. They say that whole "20% wheelspin is ideal" thing but being 5000 rpms all the way means you are a lot more then 20% at first. Not sure if want much of any spin on an Auto that doesn't break parts or have bogging problems.

Thanks for pointing out the tach, I actually hadn't looked at it on launch, but you're right. It rockets right up to 4800-5k until it hooks up. I think that alone speaks volumes. Before I ran the 2-step, it didn't do that.

I already turned down the anti-lag to +2deg. I guess I could go higher...

I was going to suggest removing timing at lower rpms to decrease power in the 2000-4500 rpms range (which you didn't seem to use at all even with a mitsu) after "maximising" your launch rpm and avoiding bogging. That will keep your turbo spooled up but decrease power and increase traction. Lots of fiddling to get that all right. Lots of test passes. You could probably keep a higher launch rpm go WOT, and then remove so much timing that it bogs and then add healthy amounts back in until it starts spinning "too hard" again.

I was thinking of keeping the anit-lag timing 'on' for a little while after the 2-step turned off, just to reduce the launch power. It will also help keep the turbo spooled...

[Vigo]

Well, if you know what rpm you are at in 2nd and 3rd right after the upshifts, pick the lower of the two rpms and declare every rpm under that 'useless' and pull back timing to help your launch. Seems reasonable to me.