4th gear pull....to long?

[cobra916]

long time ago i read how a nsx was having overheating issues caused by starting a dyno run in 4th from low rpms... real world 4th gear pullls would never happen from that low..

this should apply to all right??since no one in real world will start in 4th from 2k? wouldnt it be better to tune in short rpm bands rather then all at once?

also would a 3rd gear wot timing be the same as 4th wot timing??if knock sensors are off..

 

[RideThePONY]

I always thought dyno runs were done in fourth lol

 

[N/Angel]

dyno pulls are done in the direct gear of the transmission, so depending on transmissions this can be 3rd, 4th or 5th gear. In all Mustang transmissions I know of 4th is direct.

overheating on a dyno pull is mostly caused by insufficient cooling capacities of the dyno shop/operator

 

[01yellercobra]

dyno pulls are done in the direct gear of the transmission, so depending on transmissions this can be 3rd, 4th or 5th gear. In all Mustang transmissions I know of 4th is direct.

overheating on a dyno pull is mostly caused by insufficient cooling capacities of the dyno shop/operator

In the new 5.0's 5th is the 1:1. At least in the manuals. I do believe the autos don't have a 1:1 ratio.

Doing a pull starting at a lower rpm is better because it gets you more info. You get all of the MAF points you'd miss starting at a higher rpm. If I do any logging on the street I usually do it in 3rd. Gets me the results I need at a slightly lower speed.

 

[cobra916]

In the new 5.0's 5th is the 1:1. At least in the manuals. I do believe the autos don't have a 1:1 ratio.

Doing a pull starting at a lower rpm is better because it gets you more info. You get all of the MAF points you'd miss starting at a higher rpm. If I do any logging on the street I usually do it in 3rd. Gets me the results I need at a slightly lower speed.

what i was trying to ask..i guess i wasnt clear... is if a car is fully tuned.. like the normal way of doing things.. would it be beneficial to go back and just tune wot at 5k-7k.. start the run at 4.5k to see how the car likes timing in higher rpms.. since when racing my car will see 5k-7 only..

the overheating with the nsx was about having a long 4th gear and having no tq down low...so the run would take too long and in the middle the car would start to have issues.. kinda like how you should never 5th gear punch from low rpms a terminator..

 

[01yellercobra]

A lot of that will depend on your timing table. If it only goes up to say 6K then your timing at 7k will be the same as whatever the top load at 6K is. You could still tweak it a little if you're looking for every last horsepower. I don't really know if the time and expense would be worth it otherwise.

I've seen some llllllooonnnngggg pulls. Like we checked our watches a couple times long. If the car was overheating then there wasn't sufficient airflow for the radiator.

 

[cobra916]

A lot of that will depend on your timing table. If it only goes up to say 6K then your timing at 7k will be the same as whatever the top load at 6K is. You could still tweak it a little if you're looking for every last horsepower. I don't really know if the time and expense would be worth it otherwise.

I've seen some llllllooonnnngggg pulls. Like we checked our watches a couple times long. If the car was overheating then there wasn't sufficient airflow for the radiator.

icic thanks for the info :beer: