I have a car that I tune that is kinda lazy out of the hole. It's a solid roller LSX 422 w/ TFS 245's, Fibertuned intake, Glide and a big 6K stall. We are hitting it with just under a 400 shot Direct port setup on a progressive controller. On a properly prep'd track, we can set the controller to 100% right from the hit and hook it. Unfortunately, the best 60' is only in the mid to high 1.3x's. Then it screams down the track to a 8.70@160. The nitrous is currently setup to be interrupted by the transbrake button. It wont even get all the way up on the brake though because it's so sluggish without the bottle. We are thinking about putting a plate on it with a 75-100 shot just to get all the way up on the brake and have some nitrous already flowing thru her when the rest of it comes in. I'm wondering who else is doing this and if there are any things that I should look out for. Thanks!

 

We have done it and not hurt anything, not sure I would want to do it all the time.
Make sure you have fast reacting relays.

Where do you shift it? where does it fall back to?

 

Why fast relays?

He'd like to get up to 5,500 or so on the break. I think it's in the mid 4K RPM range now. He shifts about 7800 and drops into the high 6K rpm range. I need to look at a log.

 

We had about the same issue for a bit .try adding 4-5 degrees of timming on the brake and put some fuel in it. our car loves 12.3 and like 38 degrees of timming on the brake. If i put it at 30 and 13.0 it will lose 5-600 rpm.

 

Some of the delay your seeing could be in the relay, some switch faster than others.

It should only drop back 1200rpm when at full power (all the N20 on). if it falls back 1800rpm it needs to be 600rpm looser. that will help it 60' and not burn **** up down track.
If it falls back to far its out of the power and it has to lug its way back up which builds alot of heat = burnt plugs/pistons.

 

I used to spray my 4.6 mustang on the brake all the time, never had an issue and the car left a bit harder.

 

I have the same issue when I use the brake it falls way back.

 

We run 13* timing on the bottle. I have the timing at 26* up to about 4400 to help it up on the brake without the nitrous. Once the nitrous hits, it flashes up to 5900-6000RPM and it's gone. I cant get it up on the brake to 6K though on motor either (timing at 26* across the board over 65 KPA).

We are seeing 1.36-138 60' right now on the bottle. We need to get him down into the high 1.2's. Not sure how much more timing I can go on a 13.5:1 compression motor. Knock sensors had to be disabled as they were pulling timing on the brake and make it worse. How much compression are you running?

 

Are you talking shift extensions or when you release the t-brake before the nitrous hits? There is no drop in RPM when the car launches and it seems to be almost instant that the nitrous hits when he gets of the brake but then it re-flashes the converter. Let me see if I can get some video up so you see. It's a glide so there is only one shift.

 

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

Here you go. Last weekend at Bradenton Motorsport Park in Florida. It was really hot. Track temp was still over 100* for this pass. When we got there the track temp was 135+. We had to wait for the sun to start setting before we could get any kind of traction.

 

Shift extension.
Mine is a glide also.

Put more timing in it on the conveter it wont hurt it.

 

Just verified on a log of a 8.79 pass from Wednesday night. 1st gear shift at 7738 and shift extension drops him to 6660. So 1,000-1,100 RPM extension.

 

I'll bounce it of him and see what he thinks. He already ordered the plate for the t-brake shot so we are going to try it and see. We'll set the nitrous window switch to activate at 4K RPM just to give him that little boost to 6K.

 

sounds like its right on the money.

just needs more nitrous faster.

 

not to hijack, but if my car is having a hard time settling down on the launch (spinning) would taking out timing while on the transbrake help?

sorry.

 

Yes but only at the top and then you have to ramp it in based on the log data until you get it soft enough. If you pull timing everywhere on the tbrake, the car might have a hard time getting all the way up.
Your problem is happening after you release the button so that's where you want less timing.

Another option is a 2 step so that you can go WOT and set the launch point (RPM) to anything below the tbrake threshold. Specially usefull for tracks that aren't hooking.

 

IT WILL TAKE MORE TIMMING ON THE CONVERTOR FLASH. do this log him going onto the t brake on the motor. then put 4 more degrees in it 300 before the t brake stops to about 300 after. also put like 3% more fuel in it. then log again. If you cna real time log you can actually go up on the brake and add the timming and see the t brake push farther. don't sit on it to long 10 seconds max. let the tranny cool between trys.

we have a 14 to 1 or so and we have like 36* in ours on the convertor flash. it will help.

 

Yes. but getting the suspention right would let you hook the power better. Put a 2 step on it and start around 3K. my car as to violent on the brake so we put a 2 step in and it would leave perfect between 3K and 3500

 

thanks fellas. back on topic. lol

 

Tech is tech. it happens in all kinds of threads about other stuff. I don't think anyone cares if you helping someone.