LOSS OF HP WITH 4:10 GEARS
05-04-2006, 11:28 PM
#1
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LOSS OF HP WITH 4:10 GEARS
Has anybody glanced at the new 5.0? They have a dyno test on the new drag pak that FRPP offers for the 05-06 Mustang GT.
What I thought was interesting was they dyno'd the Gt with the 4:10 gears and the Gt lost Hp and torque...... HOW? Gears don't make power so how is this so.
What I thought was interesting was they dyno'd the Gt with the 4:10 gears and the Gt lost Hp and torque...... HOW? Gears don't make power so how is this so.
05-04-2006, 11:38 PM
#2
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RE: LOSS OF HP WITH 4:10 GEARS
if they lost hp/tq with 4.10s...jkjk
there is more friction from the engine/tranny/driveshaft/gears spinning more per revolution, but i didn't think it really made a difference.
btw, gears dont make "power", but they DO make torque. the torque at the tires at a given speed (while flying through the gears at WOT) will be be significantly greater with gears because of "torque multiplication". this is why they help the car git up and go faster
there is more friction from the engine/tranny/driveshaft/gears spinning more per revolution, but i didn't think it really made a difference.
btw, gears dont make "power", but they DO make torque. the torque at the tires at a given speed (while flying through the gears at WOT) will be be significantly greater with gears because of "torque multiplication". this is why they help the car git up and go faster
05-04-2006, 11:42 PM
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RE: LOSS OF HP WITH 4:10 GEARS
It also could have been any number of issues but my first guess would be they ran the car hotter on the pass. I have seen dyno numbers on my car vary by as much as 40 rwhp due to the engine temp.
05-05-2006, 12:51 AM
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RE: LOSS OF HP WITH 4:10 GEARS
Thanks Chevy, I had the same issue, and finally attributed it to engine temp. I ran the exact same time in Ar with 3.55 gears as I did in late April with 4.10's. The difference" In March, the car was stone cold. In Arpril the car was at full operating Temp. Ill make some more runs on May 18, weather permitting, and see if this stays true. Im going early, and icing down the engine before running.
05-05-2006, 12:59 AM
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RE: LOSS OF HP WITH 4:10 GEARS
I have always been told that gears will make you dyno a couple of ponies less. When I went to the 3.73s my car put down 284rwhp and 299twtq instead of the 287rwhp and 299rwtq it made before. I want to dyno now with the x-pipe, the ud pullies, and the better intake to see what I am making now.
05-05-2006, 01:07 AM
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RE: LOSS OF HP WITH 4:10 GEARS
ORIGINAL: 757GT
I have always been told that gears will make you dyno a couple of ponies less. When I went to the 3.73s my car put down 284rwhp and 299twtq instead of the 287rwhp and 299rwtq it made before. I want to dyno now with the x-pipe, the ud pullies, and the better intake to see what I am making now.
I have always been told that gears will make you dyno a couple of ponies less. When I went to the 3.73s my car put down 284rwhp and 299twtq instead of the 287rwhp and 299rwtq it made before. I want to dyno now with the x-pipe, the ud pullies, and the better intake to see what I am making now.
Lucy - in your case with the roush, You obviously can't play with your rev limiter to adjust for the 4.10's but as I said, it is very insignificant anyway and I'd bet money you ran the same ET cause of the temp. Throw a bag of ice on the blower for 20 minutes next time at the track and run that baby cold and I'l bet you'll see a 2/10's difference in the same conditions.
05-05-2006, 01:21 AM
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RE: LOSS OF HP WITH 4:10 GEARS
ORIGINAL: chevykiller
This is very true however it should not be that significant and usually has to do with the RPM. The lower gears will make rpm quicker and reach your rev limiter on the dyno faster which usually equates for loss of a couple ponies. Usually when you up your gears to 4.10's, you should bump up your rev limiter slightly and then you'll see the equal or gain on the dyno. I emphasize the word 'slightly' because the adjustment from the 3.55 to the 4.10's is a matter of only a couple hundred rpm. Either way, it should be nothing drastic. If you're seeing 20+ HP and/or torque loss, then it usally attributed to engine temp.
Lucy - in your case with the roush, You obviously can't play with your rev limiter to adjust for the 4.10's but as I said, it is very insignificant anyway and I'd bet money you ran the same ET cause of the temp. Throw a bag of ice on the blower for 20 minutes next time at the track and run that baby cold and I'l bet you'll see a 2/10's difference in the same conditions.
ORIGINAL: 757GT
I have always been told that gears will make you dyno a couple of ponies less. When I went to the 3.73s my car put down 284rwhp and 299twtq instead of the 287rwhp and 299rwtq it made before. I want to dyno now with the x-pipe, the ud pullies, and the better intake to see what I am making now.
I have always been told that gears will make you dyno a couple of ponies less. When I went to the 3.73s my car put down 284rwhp and 299twtq instead of the 287rwhp and 299rwtq it made before. I want to dyno now with the x-pipe, the ud pullies, and the better intake to see what I am making now.
Lucy - in your case with the roush, You obviously can't play with your rev limiter to adjust for the 4.10's but as I said, it is very insignificant anyway and I'd bet money you ran the same ET cause of the temp. Throw a bag of ice on the blower for 20 minutes next time at the track and run that baby cold and I'l bet you'll see a 2/10's difference in the same conditions.
05-05-2006, 01:33 AM
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RE: LOSS OF HP WITH 4:10 GEARS
I didn't want to get too technical Viking but your are 100% right on n/a cars. It is the inlet temp that causes the slight loss and most people just understand 'engine temp' better, but technically this is what I'm talking about on n/a cars. In Lucy's case, it is s/c and that's the exact opposite. Forced induction of any kind (N20, Twin Screw, Centrifugal, Roots, Turbo) they will run best at cold temps and see significant losses at higher temps.
The best set-up on the dyno or track for n/a cars is to start the car and let it run just long enough with hood open just to reach general operating temp and then go for it. On the dyno, having a swamp cooler aimed right at the engine helps a lot also.
The best set-up on the dyno or track for n/a cars is to start the car and let it run just long enough with hood open just to reach general operating temp and then go for it. On the dyno, having a swamp cooler aimed right at the engine helps a lot also.
05-05-2006, 01:44 AM
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RE: LOSS OF HP WITH 4:10 GEARS
One thing you have to remember is that horsepower is not measured. Only torque is measured and then HP is calculated using the following formula. (Torque x Engine speed) / 5,252 = Horsepower The change in the torque curve in rleationship to rpm can cause a loss of HP even though torque increases. A classic example are Semi-trucks. Large diesel engines produce massive amounts of torque at under 2000 rpm so the HP ratings are low for such a powerful engine. Long answer to why HP could be less with lower gears, but who knows what evil lurks in the depths of FOMOCO - LOL
Sam
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