3800 DYNO GTP

[J.E.T.]

What gear should a GTP be dyno'ed ? I remember reading a while back that 2nd gear is best. But talking to the dyno man yesterday, he says that automatics should be dynoed in 3rd gear to obtain a 1:1 ratio with 20% drivetrain loss.


J.E.T.

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[sr71_rgl]

Originally posted by J.E.T.@Dec 16 2004, 04:38 PM
What gear should a GTP be dyno'ed ?    I remember reading a  while back that 2nd gear is best.  But talking to the dyno man yesterday, he says that automatics should be dynoed in 3rd gear to obtain a 1:1 ratio with 20% drivetrain loss.


J.E.T.

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All dyno's should be done in the gear that has a 1:1 ratio which is ussually 3rd in a 3sp auto trans. Dyno'ing in a lower gear will skew the TQ reading to the high side. The hard part about dynoying our cars is to not get a downshift which will screw up everything.

 

[98 TGP TOY]

Yea i think its third. I think its suppose to give a "true" reading.

 

[fastcash]

the guys at intense said 2nd gear...i think 98% sure

 

[fastcash]

it's confirmed. straight from the intense guys themselves: "We recommend dynoing in second gear whenever possible for four reasons. First, it doesn't take as long, so it's less stressful to your engine. Second, you'll experience less heat soak on a non-intercooled, supercharged engine. Third, you'll be less likely to experience a fuel starvation issue at some speed you might never hit in real life (i.e. 140 MPH). And fourth, you won't run the risk of hitting a speed limiter (typically 108 MPH in third gear on many 3800-FWD vehicles with stock PCM's). "

 

[1BADGTP]

Flp and dyno pro have done mine in 3rd.

 

[sr71_rgl]

Originally posted by fastcash420@Dec 17 2004, 03:39 PM
it's confirmed. straight from the intense guys themselves: "We recommend dynoing in second gear whenever possible for four reasons. First, it doesn't take as long, so it's less stressful to your engine. Second, you'll experience less heat soak on a non-intercooled, supercharged engine. Third, you'll be less likely to experience a fuel starvation issue at some speed you might never hit in real life (i.e. 140 MPH). And fourth, you won't run the risk of hitting a speed limiter (typically 108 MPH in third gear on many 3800-FWD vehicles with stock PCM's). "

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All the reason you gave have nothing to do with accuracy. By dynoing in 2nd the TQ numbers will be much higher than normal. What's the point of dynoing if it's not accurate.

 

[imported_Diavolo]

the guys at intense said 2nd gear

All the reason you gave have nothing to do with accuracy. By dynoing in 2nd the TQ numbers will be much higher than normal. What's the point of dynoing if it's not accurate.

how surprising. 3rd is the way to go for accuracy.

 

[syP]

so if putting the car in 3rd, increases TQ exxentially, why not race cars in 3rd gear?

 

[imported_Diavolo]

so if putting the car in 3rd, increases TQ exxentially, why not race cars in 3rd gear?

No, 2nd will increase it. Race in 3rd gear? Well after you run out of 1st and 2nd gear, you then shift into 3rd,

 

[BumpinGTP]

Here are a couple things....
Dynoing in 2nd will raise torque by a miniscule amount (hardly even noticeable)
Dynoing in 3rd will raise max power very slightly
Both INTENSE and ZZP dyno their cars in second gear. The only time i have heard of a 'big dog' dynoing in 3rd was john tsimaris because he was spinning the tires on the dyno.

 

[kazoo]

You should be in third and if you have a DHP pcm than be above 42 mph when you floor it. It will not downshift then.