37 Deg Timing - Too Much? (HP Tuners)
07-16-2009, 09:58 PM
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37 Deg Timing - Too Much? (HP Tuners) Just learning here...I have a car that sounds like a top fueler in the burn box with no real load on it. As soon as it gets a load going down the track it sounds like someone is cutting half the air off. 330 - 1000 foot is pitiful.
I recorded the run with my HP Tuner. The timing fluctuates between 25 -37 deg between 2000 - 6500 rpm, and even ramped up to 40 deg at one point. Is that too much? I would think 37 deg is optimal.
Also, I noticed where the "injector duty percentage" never went above 40%. For the most part it was around 25-35%. Does that equate to the injectors only working 25-35% of their flow rate??
I recorded the run with my HP Tuner. The timing fluctuates between 25 -37 deg between 2000 - 6500 rpm, and even ramped up to 40 deg at one point. Is that too much? I would think 37 deg is optimal.
Also, I noticed where the "injector duty percentage" never went above 40%. For the most part it was around 25-35%. Does that equate to the injectors only working 25-35% of their flow rate??
07-17-2009, 12:05 AM
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Just learning here...I have a car that sounds like a top fueler in the burn box with no real load on it. As soon as it gets a load going down the track it sounds like someone is cutting half the air off. 330 - 1000 foot is pitiful.
I recorded the run with my HP Tuner. The timing fluctuates between 25 -37 deg between 2000 - 6500 rpm, and even ramped up to 40 deg at one point. Is that too much? I would think 37 deg is optimal.
Also, I noticed where the "injector duty percentage" never went above 40%. For the most part it was around 25-35%. Does that equate to the injectors only working 25-35% of their flow rate??
I recorded the run with my HP Tuner. The timing fluctuates between 25 -37 deg between 2000 - 6500 rpm, and even ramped up to 40 deg at one point. Is that too much? I would think 37 deg is optimal.
Also, I noticed where the "injector duty percentage" never went above 40%. For the most part it was around 25-35%. Does that equate to the injectors only working 25-35% of their flow rate??
Injector duty cycle is the percentage of a rotation that an injector is held open.
Last edited by 5.7 ute; 07-17-2009 at 12:11 AM.
07-17-2009, 12:58 AM
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I was incorrect. I re-ran the scan in super slow mode. The timing with the TPS at 100% is 22-27.5 deg timing. The 37 deg I saw and reported earlier was at the end of the track when I let off. Still not sure what the deal is. We already had the car on the dyno and paid the kid to "tune" it. It sounded like a raped ape on the dyno, just like it does in the burn box. Leave and go to the track with no other mods and it runs like it has a 4000 lb trailer hooked to it.
Are you for real - high 20's deg total advance timing is all these motors will take? I guess I am old school. We set total advance around 36/37 degrees on all drag cars with few exceptions. If 27/28 is all they can take, then so be it.
Are you for real - high 20's deg total advance timing is all these motors will take? I guess I am old school. We set total advance around 36/37 degrees on all drag cars with few exceptions. If 27/28 is all they can take, then so be it.
Last edited by b.d.d.; 07-17-2009 at 01:20 AM.
07-17-2009, 01:02 AM
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My gages on the HP tuner scanner...the IAT shows a red back face (all others are blue) and reads between 100 - 125 degrees the whole run. Is that red back face telling me there is an issue with the intake air temp?
07-17-2009, 01:11 AM
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VP 118 octane
140 psi on compression check - almost no leak down
LS6 intake
241 heads - 300 lbs seat psi
Stock pistons, rods, crank, etc
Stock lift cam, roughly 320 deg duration, degreed in
TH350 - 5000 stall
4.56 rear
No P/S
No A/C
No MAF sensor
Basic drag car....
140 psi on compression check - almost no leak down
LS6 intake
241 heads - 300 lbs seat psi
Stock pistons, rods, crank, etc
Stock lift cam, roughly 320 deg duration, degreed in
TH350 - 5000 stall
4.56 rear
No P/S
No A/C
No MAF sensor
Basic drag car....
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07-17-2009, 01:34 AM
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Because I have to run a specific octane from a few specific suppliers per NHRA. The 118 was here and I needed to use it before someone decided they needed it more than me and it ended up in a lawn mower or something.
07-17-2009, 04:13 AM
#10
Since you are running a SD tune, I'd bet you are pig rich at WOT going down the track due to the thick hot humid Summer air. With that fuel, you could run more timing (28-30) safely if you knew your AFR was safe. If you are a bracket racer, I'd bet you pick up a good bit in the evening as the sun goes down. The better air allows you to burn more fuel which will make more HP. It's better to be rich than lean since you'll be in varying conditions. Just dial accordingly.
I'd also check to see when you are going into PE. With that big stall, you may be calling for PE while staging so you'll be fat right off the line. It depends how the tuner set it up.
G/L
I'd also check to see when you are going into PE. With that big stall, you may be calling for PE while staging so you'll be fat right off the line. It depends how the tuner set it up.
G/L
07-17-2009, 12:03 PM
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I run the 110 leaded, again NHRA dictates it. This 5 gal of 118 was just here and needed to get used. I probably had 7 gal of 110 already in the tank that it mixed with. The injectors are the Ford green top 42 lb ones.
07-17-2009, 12:42 PM
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This "helps" explain why:
1. Start of run is good - no heat has built up / sensor reads cool @ 80 to 100 deg and the timing stays put.
2. Shortly after burn and launch is bad - heat builds up / sensor reads 125 deg and the computer starts retarding timing.
3. End of track picks up power - cool air blowing around at 113 mph drops the under hood temps back down to around 80 to 100 deg or so and the timing advances back.
07-17-2009, 12:56 PM
#14
I'll answer my own question here - Yes sir. Why would the intake air temp read 125 deg when it was barely 70 deg outside? Bad sensor? It's right beside the TB. When the computer senses the air intake temp too hot like that it starts pulling timing from the motor.
This "helps" explain why:
1. Start of run is good - no heat has built up / sensor reads cool @ 80 to 100 deg and the timing stays put.
2. Shortly after burn and launch is bad - heat builds up / sensor reads 125 deg and the computer starts retarding timing.
3. End of track picks up power - cool air blowing around at 113 mph drops the under hood temps back down to around 80 to 100 deg or so and the timing advances back.
This "helps" explain why:
1. Start of run is good - no heat has built up / sensor reads cool @ 80 to 100 deg and the timing stays put.
2. Shortly after burn and launch is bad - heat builds up / sensor reads 125 deg and the computer starts retarding timing.
3. End of track picks up power - cool air blowing around at 113 mph drops the under hood temps back down to around 80 to 100 deg or so and the timing advances back.
07-17-2009, 01:17 PM
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Gotcha - I'm both then. No drivability needed, just full power for 1320 feet. There are no O2's in back since I just have open headers. There are a set up in the headers used to plug the holes until I can get plugs. They are not connected to any harnesses, just plugging holes.
07-17-2009, 01:21 PM
#18
If you have the tune, post it up. As noted, you cab run OL MAF, OLSD (no MAF), or even part time OL. If the PCM is using the front O2's the the tune is CL during that time, again as noted above. If you're PCM is trying to use 02 feedback & you're running leaded fuel, then there will be problems. Leaded fuel & 02 sensors don't get along. Why only 25-35-40% injector duty??? Sounds to me like we need to see the tune. Only guys w/ HP tuners will be able to open it though. I don't have HP tuners.
EDIT: this was posted @ the same time as your reply above. So, ignore what doesn't apply.
07-17-2009, 02:01 PM
#20
Use the graph, it makes viewing timing much MUCH easier http://www.thetuningdoctor.com/HPTun...nertips(1).swf