whats the hp difference between chassis dyno and engine dyno????

 

Depends on how many torque converters you run.

 

its a dts dyno not sure

 

tony it has just 1

 

Probably reads about the same as a dynopack. lol

Fabman, i don't know if you're being serious or not. haha If not, it depends specifically which 2 dynos you're comparing, and what drivetrain components are used on the chassis dyno.

 

just trying to get a idea what is the loss in the drive train is ????say you made 1370 hp on a engine dyno whats general loss 10% 20%???

 

Depends alot on what type of engine/drivetran/etc..

I've seen a v8 make 600hp on a superflow engine dyno and then dynoed it on my dd dyno and it made 390hp...

 

I've heard general rule of thumb on a honda motor is 15-20%.

 

I think there are too many other factors to have a definite percentage loss.

 

In something like your RSX, i'd expect over 20%. From what i know, the lenco's suck up a lot of power, then there's the transfer case and front differential, "driveshaft", axles, big tires, etc.

 

From what i know from RWD cars. most of the time its anywhere between 25%-30% loss. and espceially if you are using a powerglide or something with a torque converter is more towards the 30% unless you have a real HI TORQUE motor to make up the lose in HP.

 

say 750 fpt

 

Pat,

On an engine with 335hp on a DTS, we recorded 2 days later @ roughly the same air conditions 260hp on a Superflow chassis dyno. The "car" was set up with a G-Force GF5R running through a 5.43 9" and 32" tires. We did notice a change with tire pressure and how tight the "car" was strapped down.

That being said, who cares what it would make on a chassis dyno? There isn't a good reason to dyno an engine on rollers when it's making that much power. I would be more interested in finding out how fast the acceleration rate should be on the engine dyno so that the load will better approximate what the car will see going down the track. Try something around 800RPM/sec. Pro-stock cars will see a bit faster acceleration than that.

 

thanks i will look in that...

 

so tony win you were dynoing rados car what did it make to the fron tires?????

 

we only dynoed to 18psi, made right over 600hp at 18psi. I know he dynoed later on a dynopack and made over 1000whp before it maxed the dyno out. Dynopack's max out by torque, and when you have alot of gear ratio in a car it'll max out the dyno quick.

 

Tony,

How fast does your SFWD car accelerate in rpm/sec? Don't need to know all the gears, just wondering how big the difference is between 1st and 4th.

 

Well, first gear is worthless on our cars. lol

2nd gear is ~ 2300rpm/sec
3rd gear is ~ 1400rpm/sec
4th gear is ~ 600rpm/sec

 

Thanks.

Sorry to jack your thread Pat.

That should give you a decent starting point for the RPM gain on the engine dyno.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tony1 &raquo;</TD></TR><TR><TD CLASS="quote">Well, first gear is worthless on our cars. lol

2nd gear is ~ 2300rpm/sec
3rd gear is ~ 1400rpm/sec
4th gear is ~ 600rpm/sec</TD></TR></TABLE>

Can you effectively race starting from 2nd?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by BoogieDownBrown &raquo;</TD></TR><TR><TD CLASS="quote">From what i know from RWD cars. most of the time its anywhere between 25%-30% loss. and espceially if you are using a powerglide or something with a torque converter is more towards the 30% unless you have a real HI TORQUE motor to make up the lose in HP.</TD></TR></TABLE>

My car with the powerglide locked saw right around 20% loss from the engine dyno to the chassis dyno (1660 HP on the engine dyno to a little over 1300 at the rear wheels on a dynojet), but with the converter unlocked it flashed right away and it wouldn't even make 1000 RWHP at that boost level. Dynos are very finicky to automatic transmissions, but a 30% loss is a very, very high guesstimate.