When you load up the motor at low RPM, but very heavy load..and lots of boost, it creates a lot of heat in the motor...since you are holding your speed constant, and just loading up the motor without actually spinning up the engine. This is what causes the EGT spike. If you are brake boosting at 3000rpm, for instance, but pushing 10psi of boost...you likely arent tuned with enough fuel to do this, since your car woudldnt experience that much load and boost at that RPM...under normal operation. The high engine load, at constant low RPM, generates an enormous amount of heat.

It's a valid point. However, one of the main purposes of 2-step, is to establish consistency and repeatability with your launches. For instance, at the track, one would begin the 2-Step trials at a very low RPM...say 3000rpm...and launch with your accelerator to the floor. If the car bogs, then you gradually increase the launch point until you get the desired launch behavior. At some point, you will end up spinning the tires too much, and your 60ft times will start falling off. This will be your optimum launch point, and then you can hopefully work on other things to improve your times.

 

Also, keep in mind, that when you brake boost your car isn't moving, so your radiator won't be doing much good.

 

Correct. Brake boosting, or two step should be limited to just a few seconds...thats it.

 

it sounded wicked saturday night cant wait to hear that thing back at the track

 

100% completely off topic, so I appologize in advance.

I stated in a previous thread that the ABS computer reads the wheel speed of each wheel, and then transmits the speed over CAN bus.

If this is in fact true, but removing power the VDC controller the speedometer should quit working.

If that is the case, it would be possible to install a speed activated switch that would turn the power off of the VDC controller at 150mph. This, in theory, would eliminate the OEM speed limit.

At 150+ VDC becomes pointless anyway, so its worth a shot.

Anyone want to volunteer to test this out? I already have a speed switch made for the VQ35, just have to set it for 'slightly' higher then the 10mph its calibrated to now.

Oh, and of course once the VDC computer is switched off at 150mph you would lose your speedometer most likely, I'll have to look at the service manual again to see how the cluster is controlled.

 

Looking at my timing and fuel maps it "should" be ok at that point, but I'm sure you are right about that being the cause. But I haven't datalogged at all yet while brake boosting and after I got detonation I didn't want to try it again until I figured the problem out. I'll probably just increase fuel and pull another 2 degrees of timing at that point, put in some 104, and then datalog to see whats really going on there.

 

Looks like I got a little midweek project to do then? Can I just run it the way my map is now Sharif or does something need to change?

 

Yes, you can use the same map. You will also need to goto the Vehicle Setup tab, and change the speed signal pulse to "8". This will make your speed read correctly in datalogging.

If anyone can figure out how to change it from kph to mph, I will be thrilled? There is no option for speed units of measure in the units tab..so I am stumped. It's doesnt effect the operation of the 2-step, but it would be nice to see the speed in datalogging in MPH.

 

sharif. regarding the speed sensors. there is only speed sensors in each wheel if you have abs. automatics have a revolution sensor which then goes in pulses to the tcm. the vehicle speed sensor goes from the tacho to the tcm in case the revolution sensor malfunctions.
manuals should have some type of revolution sensor that talks to the tcm. if you find that and split the sucker with a pulsed signal then you might be in business.

 

got it hooked up and going for the 2 step. not sure if it sounds like a large caliber machine gun, or just a really crappy running car, lol. cool none the less.

 

Wouldn't a "clutch pedal engaded" trigger work well for setting the secondry rev limter instead of using speed?

 

Thats how most 2-steps work I believe, but I guess Greddy wanted to be different. Works either way though.

 

I prefer a speed input, becuase each clutch is going to engage at a slightly different point, and this point will change as the clutch heats up/wears out.

 

well i was able to find something out about that speed signal last night and how traction control affects it,lol. i have the 2 step hooked up just as shariff has pictured here, and also coming on at 4000rpm. last night i was cruising around and took off spinning the tires so the traction control was starting to kick in, then it all of a sudden starts doing the 2 step ign. cut out at the same time. no big deal really, it jsut scared me for a second. dunno if this is helpful info for kevin or shariff or anyone else for that matter, but the speed signal goes to 0 when the traction control is operating. not sure if it would do the same thing during a vdc event. so the 2 step can actually work like a secondary traction control also. just turn the vdc off when you need to race.

 

Holy cow...I bet that scared the crap out of you. I have given up on VDC/Traction control a long time ago. I never run with it on....in engages at like 1/4 throttle.

 

Just setup the two step and love it. I just hate the fact that I can't get traction on 245's in 50 degree weather. I have it set at 2000 rpm and slip the clutch like mad to get any traction whatsoever. Sounds sick too.

 

lol dude I couldn't get traction in my old 200whp car on 245s in 50 degree weather. What are you doing trying to run around with 400+ to the wheels on those little things?

 

Yea, I know its sad...but good news is I'm working on it...295/35 KDW-2's should suffice for the street.

 

i might widen my 20x10's and do what it takes to fit a 335/20 rear. whoohoo, steamrollers.

 

Nice setup you guys have, but what happend to the videos
update please