Mythbusters - engine & dyno edition

[TC]

i can already say max timing=max power is false at least in a boosted application never tryed it with a N/A car never had the chance to

my 2001 grand prix with the 9.5:1 compression, 10psi boost, 1 5/8" mid length headers, and a small .520/.536 lift 212/224 duration and .050 114 LSA with a 111 intake center line cam made 280 whp at 6300 rpm with 19* total timing i could run 25* total with out knock but it lost power so put it back at 19* witch was the factory max timing at WOT

that car i could of had more boost on it though i had a pretty large supercharger pulley relitivly speaking for my set up

Isn't Max Timing the maximum timing your going to run??......Which means it does make the most power.........Max timing is whatever timing the motor runs best at, it may differ from motor to motor, but it's always the timing that makes the most power.........


I think the question is what happening to the power down the curve when you start taking timing out??.....You might get a higher Peak Number by doing it, but is their a cost to low end torque and midrange power output?? I'm not saying it's a bad thing, it might take some power out and make the car hook better...........There's got to be give and takes somewhere..........

[TheSilverBuick]

There is only one Myth I'm hoping is busted, and that's is my engine will blow up on the dyno =P

[Deaf Bob]

... So what you guys are saying...
Run your timing a * or 2 less than peak power on the dyno for the street/strip if you use an engine dyno?

And keep the timing as is on a chassis dyno?

i'll admit, I'm not much into drag racing... But it seems to me the timing is the same basically for all styles, circle track,boats and yes even demo derby...
The kid has pretty awesome "60 ft times" true, he seldom needs more than that... Still..60' is 60'

[Mater]

Isn't Max Timing the maximum timing your going to run??......Which means it does make the most power.........Max timing is whatever timing the motor runs best at, it may differ from motor to motor, but it's always the timing that makes the most power.........


I think the question is what happening to the power down the curve when you start taking timing out??.....You might get a higher Peak Number by doing it, but is their a cost to low end torque and midrange power output?? I'm not saying it's a bad thing, it might take some power out and make the car hook better...........There's got to be give and takes somewhere..........

max timing as in the maximum you can run with out KR bad wording on my part. i could run 25* before KR but it was not making the best power at 25* it was makeing max power at 19*

[JeffMcKC]

... So what you guys are saying...
Run your timing a * or 2 less than peak power on the dyno for the street/strip if you use an engine dyno?

And keep the timing as is on a chassis dyno?

i'll admit, I'm not much into drag racing... But it seems to me the timing is the same basically for all styles, circle track,boats and yes even demo derby...
The kid has pretty awesome "60 ft times" true, he seldom needs more than that... Still..60' is 60'

It gets a bit confusing.

I talked to scot on the phone I think he understands what we do better now.

If the best tune came off the dyno at 38* then we "IF IT LIKES IT" put 40* in on the line for low gear, and my even pull back the 2* to 38* in the upper rpm range of low gear. Then run 38* the rest of the way. Then to throw a wrench in that a lot of cars require a different timing and jet at the track than the dyno. Its all relitive to what makes the best run.

ET is chassis and MPH is power. Spinning a tire will and 1 to 2 mph to a car also. I dont want to confuse it more so I will stop at that LOL

The term for me of pulling 2* comes from not many ign systems will let you add timing. So you put it at 40* and then pull2* so it may sound odd to someone not in the loop for the term, I did not invent it, but learned it from the "Da Grump" in 1978 we where cutting out one set of points in my car to change the dwell ( which changes timing ) from some research on Grumps stuff.

[Caveman Tony]

so Jeff, lemme ask this:

What is the lower rpm range for low gear on one of your runs?

And I wonder what the dyno would say is better for THAT lower rpm at that timing setting vs. that same rpm at #max# timing....

[JeffMcKC]

The motor does not see under 6500 stall, and 33* timing, we have not played with the retard on this one, but I had it in 07 on the 18* engine. I geuss someone on drag week thought the button on the shifter in high gear turned on the spray for the N/A class when it took 2* out in high. and also in high going down the road it took 4* out. Using a Holley Ign system

[TC]

It gets a bit confusing.

I talked to scot on the phone I think he understands what we do better now.

If the best tune came off the dyno at 38* then we "IF IT LIKES IT" put 40* in on the line for low gear, and my even pull back the 2* to 38* in the upper rpm range of low gear. Then run 38* the rest of the way. Then to throw a wrench in that a lot of cars require a different timing and jet at the track than the dyno. Its all relitive to what makes the best run.

ET is chassis and MPH is power. Spinning a tire will and 1 to 2 mph to a car also. I dont want to confuse it more so I will stop at that LOL

The term for me of pulling 2* comes from not many ign systems will let you add timing. So you put it at 40* and then pull2* so it may sound odd to someone not in the loop for the term, I did not invent it, but learned it from the "Da Grump" in 1978 we where cutting out one set of points in my car to change the dwell ( which changes timing ) from some research on Grumps stuff.

How much does 2 degree of timing equate to in HP output?? Meaning what HP figure are you making at 40 degrees compared to 38 degrees??

[Deaf Bob]

Thanks Jeff..
Makes sense now..

[JeffMcKC]

How much does 2 degree of timing equate to in HP output?? Meaning what HP figure are you making at 40 degrees compared to 38 degrees??

Its not about HP, its about getting down the track the quickest. The first part of the track is the slowest, N/A the race is over at 330'