N/A power loss from timing loss?
03-26-2008, 11:24 AM
#1
N/A power loss from timing loss? Here's the deal-e-o.
I go to the track back in late '07 and crack off a shakedown run of 11.17@126 n/a. I had the suspension setup wrong, pushrods too short, flywheel coming loose (causing false knock)etc.
No I have it all fixed, but have 3.73's instead of 4.11's and TR-7's instead of TR-6's.
This weekend I go out N/A running 18 degrees of timing instead of 28 and it does 11.40@123mph, this is WITH all the problems fixed. On a 100 shot the time was 11.12@132 (no 1st gear spray). I figured I would fix the problems and do 11.0@126-7 and 10.70@135 on gas. The track wasn't hooking, which would account for some of the missing ET, but I don't think I should have lost 3mph from timing, especially after fixing the problems with the car.
Assume I make 540rwhp N/A on the motor tune (408 stroker), how much power loss can one expect going from 28 to 18* timing? Can't be 50+rwhp can it?
I go to the track back in late '07 and crack off a shakedown run of 11.17@126 n/a. I had the suspension setup wrong, pushrods too short, flywheel coming loose (causing false knock)etc.
No I have it all fixed, but have 3.73's instead of 4.11's and TR-7's instead of TR-6's.
This weekend I go out N/A running 18 degrees of timing instead of 28 and it does 11.40@123mph, this is WITH all the problems fixed. On a 100 shot the time was 11.12@132 (no 1st gear spray). I figured I would fix the problems and do 11.0@126-7 and 10.70@135 on gas. The track wasn't hooking, which would account for some of the missing ET, but I don't think I should have lost 3mph from timing, especially after fixing the problems with the car.
Assume I make 540rwhp N/A on the motor tune (408 stroker), how much power loss can one expect going from 28 to 18* timing? Can't be 50+rwhp can it?
Last edited by TheBlurLS1; 03-26-2008 at 11:31 AM.
03-26-2008, 12:29 PM
#2
first off dont assume what u r making. way too many variables. and i assume u r talking flywheel as 540 rwhp is very genorous given your combo imo. 2nd 10 degrees less timing is a lot of timing. id say u are prob leaving 25hp on the table n/a. but if u dont have a way of pulling timing on the spray then u have no choice really. and there are several variables with mph loss. its really impossile to compare the runs unless all else was equal which it sounds like it def wasnt. traction can account for all kinds of mph u never thought possible. my old car could vary as much as 6 mph in the same night with a run i had traction vs one that a didnt. i wouldnt be too worried until u get some actual solid runs on the car.
03-26-2008, 12:38 PM
#3
10* is a ton of timing. I would expect a good size power loss from it. Also, you said you weren't hooking very well that night correct? Well, that is your explanation for the trap speed loss. As far as the original timing issue goes; if you dropped ten degrees of timing and only lost .2 seconds I would be pretty satisfied. Get some could traction on your nitrous runs and you should see into the really high ten second realm.
03-26-2008, 02:10 PM
#5
+1. I would pull less than 3-4 tops for that small of a shot.
I do pull 10 degrees in a 400 shot and I have run on motor just to see what it costs power wise. Same day I ran a 10.72 @ 126 1.5 60' and then with the timing out I ran a 11.01 @ 123 1.55 60'. Everything else was the same. Both were perfect launches with zero wheel spin.
I do pull 10 degrees in a 400 shot and I have run on motor just to see what it costs power wise. Same day I ran a 10.72 @ 126 1.5 60' and then with the timing out I ran a 11.01 @ 123 1.55 60'. Everything else was the same. Both were perfect launches with zero wheel spin.
03-26-2008, 03:26 PM
#7
I was having some issues with what I thought was pushing water, which is why I pulled so much timing. I rigged up a coke bottle on the overflow to monitor. It got about 1" of water in the bottom and didn't gain any more the rest of the night, even hot-lapping it, so I'm ruling that out. I plan on running more timing from now on. I am running PUMP gas with 11.5:1 SCR btw.
As for traction problems, I was cutting 1.75's with the pinion set wrong, but only 1.90's this weekend. The car dead freaking hooks on the street. I have sprayed it with a 50 shot (testing stuff) on the street and it hooked in 1st. At the track this weekend the tires would come loose at the top of 1st on motor.
+1. I would pull less than 3-4 tops for that small of a shot.
I do pull 10 degrees in a 400 shot and I have run on motor just to see what it costs power wise. Same day I ran a 10.72 @ 126 1.5 60' and then with the timing out I ran a 11.01 @ 123 1.55 60'. Everything else was the same. Both were perfect launches with zero wheel spin.
I do pull 10 degrees in a 400 shot and I have run on motor just to see what it costs power wise. Same day I ran a 10.72 @ 126 1.5 60' and then with the timing out I ran a 11.01 @ 123 1.55 60'. Everything else was the same. Both were perfect launches with zero wheel spin.
I think I'm going to try and ramp it up to 20 or so on he 150 hit, which I have in it now. I threw those jets in looking for a 10 second slip and went down to 16* just for safety's sake. First run I had to lift and wasn't worth a ****, same MPH as the 100 hit. Last run on 150 I spun at what I thought was about 5800-6k(on motor), lifted and got back in it but I must have already passed the window. This caused the controller to think it was in 2nd. Then the tires REALLY spun when the spray kicked in (still in 1st) and it hit the limiter. I think this caused the lean shut-down switch to disable the spray for the rest of the pass because it was another 123mph slip.
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03-27-2008, 01:02 PM
#8
I dynoed my car a couple of weeks ago and by adding 7 degrees of timing I gained 43 rwhp with no other changes. Was set at 15* originally ( for a BIG shot ). Also this was on a mustang dyno with a big stalled TH350.
j/k
03-27-2008, 06:01 PM
#10
I've been busier than a 1-eyed cat watching 2 mouse holes. Good news is my desktop started working again and all your pictures are still safe.
I'll give you a ring sometime this weekend.
03-31-2008, 07:56 PM
#14
Robert
