Anyone set up a throttle stop???

[dysan]

I'm thinking of attempting to do a throttle stop of sorts on my car for the up coming race season and wanted to see if anyone has attempted that on the stock pcm for the 3V cars? Lito advised me that the pedal has 3 potentiometers, two go one direction in voltage and the other is opposite and the computer checks against all of them.

My thought is to use 3 relays or something of the sort in conjunction with a timer in the delay box so when they activate they show the computer the voltages that are called for when the throttle is closed.

Any input from anyone??

 

[Captainstr8edge]

a screw through the pedal and a piece of wood?

 

[dysan]

Hah....wrong type of stop...timer controlled that will shut the throttle blade for whatever amount of time I dial in on my delay box.

 

[conexion914]

Good question!

I have a friend who is into electronics (green boards and such) and has 2 degrees in it. We are toying with the idea of finding someway to mask the pedal voltages for about 1800rpm, so that I can have a two step without the two step since MSD's only goes to 2000rpm.

I'll be watching this thread and if I find anything out that's worthwhile I'll share it.

Good luck, man.

 

[dysan]

I appreciate it...why don't u use the n2mb wot box? I don't believe it has that lower limit that the msd does. I can check mine if u want since I used the wotbox in my car.

 

[conexion914]

I have thought about going that route and may just for simplicity's sake.

I can't go much past 1800-1900 on the converter or I push through the skinnies.

I also thought about the route I mentioned above as it will probably be friendlier to my axlebacks lol.

If you have a chance and it's easy to do that would be great man! Thanks!

 

[dysan]

So u plan on footbraking an auto while using a 2-step, hmm.....as far as being bad on your axle backs u shouldn't have a problem. The issue comes from the no lift shift in a stick car, not from the 2step feature. U won't get a backfire with the 2step.

Now depending on the race u may be better off with your original idea so it doesn't sound like you are on a rev limiter. Only matters if u are in a class that doesn't allow electronics such as a 2step. I doubt they could detect it if u managed to mask the pedal voltage.

 

[conexion914]

That was the plan anyway. With the drive by wire it's touchy to get it to the same rpm without being jumpy. I would usually prestage and then start bumping, but the bumps would bump my foot and I'd be all over the places. Lately I've just been bumping at idle and then bring it up once I'm staged.

I bracket race and just want to be consistent. In the class I'm in there aren't any rules about 2-steps as other guys use them.

 

[dysan]

Tried to check about an hour ago only to find out that the software for the usb to serial adapter I use doesn't work correctly in windows 8.

I'm 99% sure you can go very low rpm on the 2-step with the wotbox. I believe againstallodds1 tested his out around 1500rpms or maybe even less to try out the 3-step and it worked.

When I get a chance I'll try again using my windows 7 laptop.

 

[conexion914]

Thanks very much! I'll let my buddy know about what you've found and see if he can diagram something out to test.

 

[dysan]

Hopefully in the next few days I can check how low I can set the wotbox...my new usb-serial adapter arrived today that will work in windows 8 but now I need to find the time.

 

[ondabumper]

I tested it as low as 1200 before. It works with the WOT box.
The MSD wouldn't even work for me at 2,000.

 

[conexion914]

I tested it as low as 1200 before. It works with the WOT box.
The MSD wouldn't even work for me at 2,000.

Thanks, man!

 

[kazman]

I'm a little confused on what your trying to do. Are you looking for a throttle stop to reduce your ET or something to set launch rpm for RT?

I take it that your doing a little bracket racing.

 

[dysan]

Heh...yes it is for bracket racing and yes it is a throttle stop to reduce my ET. Lito and I tried changing the throttle percentage in my tune but it really doesn't do much with a TVS blower. The blower just sucks the air right past the throttle body even when we set it down around 65% throttle and the car didn't slow down.

I haven't had any time to mess around with it yet because I'm trying to get my car to pass inspection. Once that is done and I can put everything back to my race set-up on the car I'll try and find time to mess around with the pedal.

 

[kazman]

Another question lol. What class and track do you race? Div 1 rules are special. Super Pro and gamblers races are the only place where throttle stops are legal.

 

[dysan]

I do run gamblers on Tuesday nights and I'm also thinking of running super street which is a 10.90 index.

I need to see what my car is going to run with the new engine first before I make any decisions. If it can't run 10.0 then I'll probably keep it dialed back for 11.50 in which case I won't need any throttle stop.

 

[kazman]

I don't think you need the throttle stop for the gamblers race unless your trying to drop spot. IMO most running there (gamblers) are going to run it out and those who drive the stripe are very very good. Either case the drop spot isn't effective. Your could always lift at the mph cone and coast across. That might get someone to break out. Dialing real soft and dumping hard in the box might be a good way to go against the hitters who drive the stripe. Doing that won't let them react to your move. Just be careful not to lock the brakes up and skid across the finish.

Pick a spot on the track to lift for the index races. I was lifting at the 1/8 mile marker, counting outloud 3 mississippis and geting back on gas. That scrubed about .5 and got me close enouogh to the 12.0 index to drive the stripe. I picked the 1/8 because the spot was after I got into high gear and gave me enought time to look at the opponent and judge finish line.

The other place I drop spot is on the 1000' marker. I lift as my shoulder passes the cone and count outloud 1 mississippi and back on the gas. That scrubes .1 off the ET.

Another tactic that I use in brackets is short shifting. I have a turbo 400 and shift at 5400. This is my 'normal" shift point. I can pick up a full .1 simply moving both shifts to 6400. So reguardless of my dial I'm holding a tenth in the bank.

My very first time on the track was at Raceway Park.

 

[kazman]

That was the plan anyway. With the drive by wire it's touchy to get it to the same rpm without being jumpy. I would usually prestage and then start bumping, but the bumps would bump my foot and I'd be all over the places. Lately I've just been bumping at idle and then bring it up once I'm staged.

I bracket race and just want to be consistent. In the class I'm in there aren't any rules about 2-steps as other guys use them.

I have my street car ('07 GT auto) set up to go very shallow off the second amber. I don't have to worry about launch RPM.

 

[dysan]

I was doing that all last year and it was a pain. I also tried short shifting but that really didn't do squat with my car. I did my "manual" throttle stop at the 330' mark on my car but against some of the vehicles I will be up against at Atco it's not going to be nearly good enough. I need something that will be very accurate (.005 accurate) and that's only going to happen with a delay box and an electronic throttle stop.

There are some killer racers at Atco so if I can rig it up I will. I'm going to be racing a street car against purpose built drag cars so I need every edge I can get.