dyno's

[crazy dave ls1]

OK I had my car tuned and dyno'd at one place @ 327.3 rwhp,347.0 rwtq.Added a lid and 3.73 gears and dyno'd 313.5 rwhp,330.1 rwtq at another place. Both were dynojets.My question is could the dyno's be that different?WTF?

[Johns00Z28]

I think the addition of your gears will actually show lower numbers on a dyno but there could be other factors like the temperature, elevation etc.

[crazy dave ls1]

thanks for the reply.I'm still a bit confused.I understand about climate,humidity and temp but I was under the impression that the lower the gear the easier the engine could spin up meaning more power at the wheels.I guess I am wrong.It's very frustrating spending your hard earned money for mods only to see your hp/tq drop instead of climb.Oh well another newb lesson learned.

[c5z28]

the gears do lower hp readings I don't know why but they do, your cars faster though.

[BaltimoreZ28]

gears are more about acceleration vs top speed and not so much about hp

[Johns00Z28]

thanks for the reply.I'm still a bit confused.I understand about climate,humidity and temp but I was under the impression that the lower the gear the easier the engine could spin up meaning more power at the wheels.I guess I am wrong.It's very frustrating spending your hard earned money for mods only to see your hp/tq drop instead of climb.Oh well another newb lesson learned.

Yeah your car is faster even though it shows lower numbers....I wouldn't worry about it. Just continue modding away and having fun.

[crazy dave ls1]

thanks guys

[karpetcm]

The only explanation i got for gears is since it has more teeth it translates to more power loss, dont know how true that is. I did fine on the dyno with the gears and if i were you i wouldnt worry about how much RWHP or RWTQ your putting down but how well your car uses what it puts down, especially now that its much quicker.

[ebdboudreaux]

Gears do NOT have any affect on wheel hp what so ever... All gears do is change the power delivery...

[sct771]

My understanding on how the dynojet works is how many times your car spins those 2 rollers and how fast it can spin them and i think those rollers weight about 2700lbs or so. Having a set of lower gears for example 3:42 which is stock will rotate those rollers faster and more times than the same car with 4:11's. This would explain for you losing HP in the two seperate dyno tunes. Your car is faster though 1/4 mile though because you gain greater acceleration top end but lower your top speed.

[TRANS-DAD]

My understanding on how the dynojet works is how many times your car spins those 2 rollers and how fast it can spin them and i think those rollers weight about 2700lbs or so. Having a set of lower gears for example 3:42 which is stock will rotate those rollers faster and more times than the same car with 4:11's. This would explain for you losing HP in the two seperate dyno tunes. Your car is faster though 1/4 mile though because you gain greater acceleration top end but lower your top speed.

Are you sure?
So your saying that if my car make's 400rwh w/3.42 gear
then if I just change to a 2.73 gear it would dyno at 430-450rwh?

[sct771]

That's alittle bit extreme. All things being equal then you dyno your car the difference I heard can be about 5 hp or so. depending on how radical your gear change is of course. The lower gear ratios like 4:11's provide more low speed wheel torque and lower engine speeds. The sacrifice for opting to use lower gear ratios is lose in fuel economy and having to shift more often during daily driving. I'm not an expert at this issue but I just know that different gears can change the numbers a little bit.

[ebdboudreaux]

Some of you all just need to go on google and do some searching on "how gears work" because some of you give radical, incorrect, explanations...

[sct771]

Here you go. Read up.

http://www.smokinvette.com/corvettef...ad.php?t=15829

[karpetcm]

Dont know if it was there or not but i went through it and couldnt find anything about gears just different dyno machines and how they contribute to different numbers. Ok went back and read it, it is in the 1st paragraph, so basically a car with 4.10 gears show's less RWHP on a dynojet.

[sct771]

read the whole thing. It clearly states that gears most definetely affect dyno numbers. It's in the first paragraph.

[Y2KArcticSS]

read the whole thing. It clearly states that gears most definetely affect dyno numbers. It's in the first paragraph.

I caught you, posting in the wrong thread. My post was right above yours and I was like, huh???? When did I mention dyno?

[karpetcm]

Since a vehicle with a lower gear ratio can accelerate the mass to a higher speed using less engine RPM, it will show a higher horsepower number than a car with a higher gear ratio. If a car is able to accelerate the dyno’s rollers from 200rpm (roller) to 300rpm (roller)in 1500rpm (engine), then the dyno is going to record more power than a car that did that in 2000rpm (engine).

Just copied and pasted this piece of the paragraph.

[Y2KArcticSS]

Since a vehicle with a lower gear ratio can accelerate the mass to a higher speed using less engine RPM, it will show a higher horsepower number than a car with a higher gear ratio. If a car is able to accelerate the dyno’s rollers from 200rpm (roller) to 300rpm (roller)in 1500rpm (engine), then the dyno is going to record more power than a car that did that in 2000rpm (engine).

Just copied and pasted this piece of the paragraph.

In that case, I'm getting some 5:77's just for the dyno

80 mph in 6th gear at 5500rpm going to work though

[sct771]

exactly.Is there a problem with that part or something.