Percentage diff between a Chassis Dyno and an Engine Dyno
 

Can anyone give me a ball park figure?

Re: Percentage diff between a Chassis Dyno and an Engine Dyn
 

Average stick car is 15%. Automatic cars with stock torque converters are close to 20%. Those numbers were in the literature that came with my dyno, and usually proved to be close by shops I tune for that had both kinds of dyno.
Hope this helps.

Re: Percentage diff between a Chassis Dyno and an Engine Dyn
 

Almost 2 HP per cubic inch. And we might have valve float, or lifter pump up over 7000 rpms

http://i203.photobucket.com/albums/a...11094419PM.jpg

Re: Percentage diff between a Chassis Dyno and an Engine Dyn
 

I think he's asking how they compare in test data to one another; after the drive train loss calculations I assume.

Re: Percentage diff between a Chassis Dyno and an Engine Dyn
 

Jeff, I thought he was. May have mis-read it. Thought that was what I answered.

Re: Percentage diff between a Chassis Dyno and an Engine Dyn
 

It also may vary depending on the type (load bearing edy etc) and brand of the dyno. The operator will also play a roll in it. You can make them read what ever you want. Mustang and Dynojet are the 2 most popular chassis dynos, and Mustangs tend to read a good deal lower. All though it may argued, one may not necessarily be better than the other. In the end most good tuners will tell you that chassis dynos are more of a tuning tool to help compare you percentage of change in power more so than actual power number. Not sayin that the numbers are not accurate. Its just a fiercely debated topic.

Re: Percentage diff between a Chassis Dyno and an Engine Dyn
 

We first ran the car with the box (caravan) manifold. The switched to an ITB set up.
We saw a 10 HP increase through out the range, and an almost 10 foot pounds of torque with a broader flatter curve.
This was a Dyno Dynamics Dyno I don't know how to compare it with a Mustang or a Dynojet

Re: Percentage diff between a Chassis Dyno and an Engine Dyn
 

Id say no matter what they read thats a good gain Art! Dyno dynamics read like a Dynojet from what Ive seen. Specifically the models that bolt to the hub instead or running on rollers.

Re: Percentage diff between a Chassis Dyno and an Engine Dyn
 

Actually I just went to their website. Don think thats the brand I was thinking of.

Re: Percentage diff between a Chassis Dyno and an Engine Dyn
 

It was on rollers, no bolting anything to it. that might be a hard to do with a fwd.

Re: Percentage diff between a Chassis Dyno and an Engine Dyn
 

As with any dyno, the numbers don't actually matter, it's the DIFFERENCE you see from the changes that matter. The shops I was refering to had Super Flow engine dynos and Dyno Jet chassis dynos. Mustang dynos don't alwaye read lower. Depends on the operator and the load factors they use. When the ATI Procharger people hauled their prototype cars from my shop (Dynojet), after tuning, to their place (Mustang dyno) they typically picked up around 5%.

Re: Percentage diff between a Chassis Dyno and an Engine Dyn
 

Only thing I can tell you is my car lost 28% on chassis dyno.It was automatic then. Dynoed engine on superflow SF900AT It was calibrated as close as possible,air corrected to 29.9 baro 60 degrees. Then later we got a Dyno jet chassis so my car used to test it lost
28%.
As Ed said don't compare your # to others,just look at gains from where you started.
I don't know about others but dyno jet has setting where you let car coast after pull and it calculates driveline drag or % of loss I can't remember term they use.
I don't have much chassis dyno experience but in my opinion they probaly not as repeatable as good engine dyno.
Mike Taylor 3601

Re: Percentage diff between a Chassis Dyno and an Engine Dyn
 

Mike your sure right. A race converter causes more loss, also converter & fluid temp changes effect slippage losses. Tire slippage is another variable. Had a 10.5 car bring his car two days after it was on Reher & Morrison's engine dyno. His showed a 28% loss also. Mine has never been on an engine dyno. Sure hope mine looses more than 28%! LMAO!

Re: Percentage diff between a Chassis Dyno and an Engine Dyn
 

Ed,
Good morning.
Are you saying the HP math on your car is: 0 - 28% = 0 ??? :~)

Re: Percentage diff between a Chassis Dyno and an Engine Dyn
 

Pretty darn close. :-(

Re: Percentage diff between a Chassis Dyno and an Engine Dyn
 

Ed
Took a minute for that to register,your're saying you hope your driveline is worse than 28% so your engine is making more than what chassis dyno is telling you.I'm from Ky. takes me a minute or two sometimes.
I hope to have mine back on chassis dyno soon to test X pipe different mufflers,I'm interested to see how much less stick uses.
Mike Taylor 3601

Re: Percentage diff between a Chassis Dyno and an Engine Dyn
 

Mike, that's what I meant. Maybe my Okie accent makes me hard to understand. LOL