D-Rob

Hey guys,

I don't post real often these days (adult life and the shop keep me pretty busy), but I wanted to share with you something I have been working with lately.

As some may know, I competed in a 1,600ft, 60mph rolling-start racing event at Pocono Raceway in July. The experience was incredible, and I had a great time racing with 1,200hp GTR's and 1,300hp Lamborghini's.



The biggest problem I had was holding speed steady as I crossed through the first cones. Because of this, I usually ended up starting a bit too slow, or sitting in third gear waiting to make power until about half track, thus resulting in playing catch-up with everything all day.

Example: me racing a Supra at the last event. I was lightyears behind until the last couple hundred feet, when I slingshot past.


After that race, the owner of the Supra and I started talking and he asked if my ECU supported "rolling launch control". At that point, I said "no," but later after the event, while conversing with my colleague John Kerr here @ IMW, he suggested something that sounded like it would work.

Here is the method I have used recently, and tweaked over the last two weeks. This allows me to hold a steady speed (since the rules of the next event have gotten more strict on starting speed accuracy; radar will be used to ensure all vehicles are moving within a 3mph window of 60mph ground speed at the start of the run, or you will be disqualified), make enough boost that the car "launches" instead of starts it's spool, and keeps your brakes cool (brake boosting works well, but I didn't like the idea of over-taxing my brakes at the start of the run, and again at the end, when I have to take Turn 1 of Pocono Raceway at 150+mph).

Below is a photo of my brakes after coming back from a 163-mph pass.


First, I used GPS to verify 60mph ground speed, and popped the car in the gear I would be using to start the run. In my case, that's third gear @ 5,600rpm.

Once we know the engine speed, we do our prep work in K-Pro. Below is my exact current settings that allows me to build 18psi or so at 5,600rpm, while holding the car at a GPS-verified 60mph at WOT.



As you can see, I am using an input to activate this feature. THIS IS WHAT ALLOWS THIS WHOLE THING TO WORK. Setting Launch Control to "Always On" will NOT work for this trick.

In my case, I am using E22, the 12v brake switch input, to turn this all on. The first couple times I did this, I was using a switch I had wired to the ECU to do everything, and had to take my left hand off the wheel, resulting in some "surprising" events as soon as I would flip the switch, releasing the car from the launch control. I have since converted my windshield wiper stalk's "wash" function to send a 12v signal momentarily (as long as the wand is pulled towards the steering wheel) to the E22 input.

In order to keep the car stable at the target speed, the Fuel/Ignition corrections are activated VERY close to the Launch RPM limiter. Any larger variation here seems to waver vehicle speed more than I like.

You'll notice the Maximum Speed is also set very high. This is set accordingly higher than whatever the target speed is, so as long as the car is moving in the speed range you need to target, the ECU won't disable the launch control until you release the input (again, in my case, the wiper wand).

And that's it. Simple. The result of this on my stock K20 with a T3/T67 is instant boost and acceleration the moment I release the input, which is a HUGE improvement over just holding engine speed at narrow throttle and flooring it at the start of the run.

As always, I don't recommend prolonged use of this feature. A couple hits of the limiter is enough to make a LOT of boost. I'll see what I can do about grabbing some video.

I do believe this will work on pretty much any of the OEM Honda ECU editors/systems, also. The only downfall of this method is that it is limited to ONE specific speed target.

If anyone has ideas on improving this feature, I'm all ears!

Thanks!

- Derek

Muckman

iTrader: (2)

I would love to see a video of this in action.
Great contribution D-Rob. Thank you!

turbohatch96y7

iTrader: (15)

Seems simple enough..


I think in aem you could set a limiter based off tps percent. At 5600 rpm and all that retard I can see you building boost really really fast especially under load.

ferio-ichi3

Amazing. Not everyday you see cars. Like this come from pa. Good show!

1lowek2007

Weird that u posted this Derek. We just finished this on my k20 Mr2. Works very awesome. Glad to see I wasn't the only one with this idea for kpro lol.

Robs_B18c

iTrader: (1)

Sounds pretty cool. Video of this in action would be nice.

D-Rob

If I get out of the shop at a decent hour tonight, I will take some video!

Dark_Teg

This seems a lot safer than the brake boosting method a lot of imports use.

turbohatch96y7

iTrader: (15)

K pro doesn't allow a limiter based off tps?

Something like 80percent tps limits rpm at whatever your rpm needs to be then at 100 percent the limiter is removed.

Seems like it'll respond faster.

extremeracer

Very cool, I've gone for a ride in a GTR with this feature enabled on Ecutek and it will be even more effective on large turbo, peaky setups like our cars.

D-Rob

Two quick and dirty videos showing it in action.



Have a little adjustment to speeds yet, but it works.

NOTE: The speedo is using a Speedohealer v4 to convert the indicated speeds to MPH, if anyone is confused.

V-SPEC 1

Nice.

monjarassi

fkn sick, fwd ftw

LightningTeg

Awesome man. This is something I need to setup. I do TONS of roll racing

justYncredible

iTrader: (1)

You have become everyone's hero! I'm going to want to set this up on my s300. Can you still have regular launch control (dead stop) with this? I would think not

extremeracer

If you don't require the retard and enrichment function (so basically just a fixed limiter) then you can use the burnout rev limiter activated with a different input, but it won't have any other activation or de-activation conditions (speed override)

boosted k20

I always thought about putting a push button normally closed switch in series with the speed sensor signal wire. When you want anti-lag on the roll just push the switch down and it will cut the speed signal to the ecu making it think its at 0 MPH. Letting go of the switch will turn speed signal back on and car will drive normally.

Charlie Moua

iTrader: (3)

very cool

crxtc_vtec

iTrader: (2)

Nice!!!!

wantboost

iTrader: (2)

JK is a wiz kid lol... I remember our long talks on AIM back in the day, still want to try out his nismotronic on one of my sr builds.

how are you liking the Speedohealer? I've used them a lot on our race bikes and need something to correct the Speedo on my civic due to tire size, when it says I'm doing 55 I'm actually doing 45 :/

hussain-vtec

Nice work !!

gringotegra

Haha, ive had this same thing setup since TX2k...

I am still not sure it works AS good as some good old brake boosting..But it is pretty cool to hear it pop and spit when you are moving hahahaha

D-Rob

Right. After using it for a handful of runs this past event at Pocono, I'm not sure which is better yet.

gringotegra

Yeah I mean it sounds cool. But I can brake boost 20psi in 3rd. and I just feel like there is a slight hesitation when it's on.

ferio-ichi3

Hey D-rob, can i come back to the shop and talk about cam choices? Or should i make an appointment?lol