I went to the dyno last week and sparyed a 200 shot, only picking up 150hp. I went again today jetted for the 250 and only picked up 152hp!!! I'm running a NX dp kit, ngk -9 plugs, 105 unleaded fuel, th400 with vigilante 4000 stall. Why am I only picking up that amount? The crazy thing is that when my a/f went from 10.3 to 11.4 I't only picked up about 1-2 hp. I'm pulling 10 degrees out. There are two things I can think of....1) TCI trannies eat up a huge amount of power(145hp including what I lost NA. 2) I have a restriction somewhere in the nitrous system. I pulled about a total of 25 seconds and used about 7lbs of nitrous on the 250 shot, so that seems about right. Please help guys!!
Thanks, Chris

 

You may need some SHO lines im not sure but im sure the Robert or Matt will have some ideas

 

you could be blowing thru the converter too... dyno #'s and stalled automatic's don't really work well together. Hav eyou tried the hit's at the track? I'd suggest pilling it back to where you had it at 200, and try runnign it at the track, and check teh plugs afer teh run to make sure it's o.k., the load the car sees at the track might make thigns different then it was on the dyno. FIgure out teh power by the trap speed and your weight, that will proabably give you a # for referance, and then if everythign looked good on teh 200, up it to the 250 and see what that gets you.... probably see something at the track I'd think.

 

my n20 guy told me. with a 100 shot you should go threw 1lbs in 10 seconds. 250 shot, 25 sec. 7lbs sounds a about right.

 

I really think my tranny isn't good. Do you guys think that the tranny could be wasting the power? or just the converter?

 

That is possible if its slipping

 

Get it to the track screw the dyno on nos tune ups.The only thing i use a dyno for is a motor tune and then the fun begins on the bottle at the track. Dynos are for baseline tunes.Don't become a dyno queen.

 

Generally speaking how much mph should I pick up with an extra 50 shot?1/8th mph and 1/4 mph? What abbout time as well?

 

I've always heard Vigilante verters are very loose and inefficient, you may be spraying through the verter.

 

Devon, I was getting the same pickups when I had a tci 3800. It stalls right at 4000 n/a

 

I'm just out of ideas guys, and spent alot of money on dyno tuning, and not getting much out of it.

 

****, don't know then, that's weird dude!

 

I have a hard time believing that a tranny would do that. Its just carzy, because when I had a six speed in, I picked 160 on 150 shot, thats why I don't think it is related to the nitrous system. But how could a tranny just stop prodcing power at x amount of nitrous. Here what the numbers looked like....
Previous Visit Today
372N/A 385N/A tuned it a little
525 200 shot 535 250 shot
+152 +150

 

As previously stated you could very well be keeping the convertor in a range where it is not allowing all the power it could to the ground. One misconception is that convertors ranges that are good for N/A apps or a certain N2O setting will be good for a higher jetting as well, this is not always the case. If you think about it with a higher jetting you are going to be making more torque in most cases. While 25-50 hp more may not seem like allot it could be the point in which the VE of your motor combo comes into play and it could be making a good deal more power than you would think. As such it could be making the convertor slip more than what is ideal and there-by causing the lower readings. It is also a well known fact that it is difficult to get an accurate reading on a chassis dyno with an automatic without locking the convertor. With a TH400 I am assuming that you are unable to lock the convertor and as such I am sure you would be more pleased using the track speeds as a HP/TQ indicator. More often than not most N2O users use a tighter convertor even with a progressive system. Try giving Kevin Winstead at TCI a call. When I upped my N2O I had my SSF tightened up and as a result my car picked up a couple of tenths. As the other gents have stated dynos are great for tuning and 6-speed cars but for an automatic you really need to get it to the track and see what is what. I would venture to say that you are probably going to end up tightening it up a little. Hope this helps.

Jim C.

 

Chris, give us a little more info please such as camshaft specs, gear ratio and car weight loaded with you and fuel. As it stands right now unless your car is super light and or has a buttload of gear and camshaft I am going to say you need to tighten up your convertor a touch. Did you tell Precision all of these things when you got the convertor? Also is it a 10-in unit or smaller? Trap speeds and your RPM when you cross the finish line will tell allot more of the story.

Jim C.

 

Ok you did not blow it up, so the dyno time is well worth it.
Now some questions
What type of systems? 2 or 4 noid
what jet numbers?
what fuel pressure?
what size feed line?
Do you have a pic on the intakes plumbing?

one pound for 10 seconds is close so on 250 shop for 25 seconds and use 7lbs.? seems alittle high nubmer.

Did you call into NX yet?

could be a couple of things.
1 the converter is flashing harder/blowning throw the convertor
2 tune up is way off
#2 would show up on the a/r chart.

Ricky

 

I think your plugs are too cold...try -7 with the 200 and maybe -8 NGK's with the 250.

 

i'm going to bet its blowing through the converter. the dyno is not the place to get your #'s from with a th400 and big stall either.

 

Chris,
Yes it is true that you can loose power from a poor tranny or loose convertor.
However with all that aside I see a few things off the top.
#9 plugs for a 200 or 250 are to cold. Try 7s like suggested above. Gap for 32-35.

Keep the airfuel about 11.5 to 11.8

Timming is about right. Going to the 250 you may pull another 2 or 4 degrees and with possibly adding alittle back in depending on how the spark plugs and knock look.

Dave

 

The cam is a 240/246,.590/.610 109lsa, ported 190 afr's. The rear gears are 4.1 the car weighs 3575 with me in it. It is a 9.6" verter. I'm at the end of 2nd at about 6900. I trap about 102 in the eighth, no 1/4 track around here.