IRS and chassis dynos...
Thread Starter
Burning Brakes
Joined: Oct 2020
Posts: 1,149
Likes: 265
From: The frozen wastes...
IRS and chassis dynos...
Just curious if anyone here has chassis-dyno'd their Corvettes. I'm wondering if the IRS eats up more horsepower than a solid axle, and if it does, how much. I cant see it not making a difference.
Burning Brakes
Joined: Nov 2011
Posts: 1,170
Likes: 201
From: Willoughby Ohio
I know of 2 guys on here with dynos. Pauldana and 632C2 who are Paul and Steve. Both are great guys and will answer any questions you have.
Last edited by 76strokervette; Aug 31, 2021 at 02:37 AM.
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
If there is a difference.....it is negligible. What would eat up the power? You still have a ring and pinion, and a set of bearings......the halfshafts should be straight or close to it....I doubt there is difference at all.
Jebby
Jebby
Safety Car
Joined: Nov 2005
Posts: 3,532
Likes: 1,185
From: Arizona - If you don’t know CFI, STOP proliferating the myths around it...
Yes, my 82 has been on various dyno's a lot over the years. At one time, I thought my car was a dyno queen. But anyway, I do not think that being a IRS has a bit to do with power ratings. However, with that said...It does matter how tight the car is strapped down and will/can have an affect on power, but that's on any car. Also, my car has been on a few different Dyno Dynamics dyno's which are called "heart breakers". They all seem to be more realistic on the results vs a Mustang or DynoJet, but you can manipulate the dyno as well. I like the Eddy Current Dyno Dynamics. 
Last edited by Buccaneer; Aug 31, 2021 at 07:13 PM.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Mass doesn't detract from the static HP numbers. It just takes a bit more time to get it wound up (inertia of rotating mass). There might be some insignificant amount of added friction in the bearings due to added mass....but I doubt any commercial dyno would notice any difference.
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Thread Starter
Burning Brakes
Joined: Oct 2020
Posts: 1,149
Likes: 265
From: The frozen wastes...
People go through trouble to lighten diff internals, axles, etc. and an IRS has actual spinning half shafts, which are what? 2.5" to 3" each? with 2 U-joints each, as opposed to just a thin axle and a thin flange ov a few inches. Also, Cobra guys have picked up MPH just by going solid axle over their IRS, and Mach 1 guys (solid axle) tend to dyno better than Cobra guys... with pretty much the same damn engine. Just wondering if its worth even 5-10HP on a 300-400HP engine is all.
Safety Car
Joined: Nov 2005
Posts: 3,532
Likes: 1,185
From: Arizona - If you don’t know CFI, STOP proliferating the myths around it...
You are debating over "maybe" a couple of HP if that, for a street car which I find ridiculous. If you were racing competitively and every .01 or tenth counts, then do it if it makes you feel better, but I think this is craziness in a street car and not worth the effort or cost IMO. GL with your build and dyno pulls.
Thread Starter
Burning Brakes
Joined: Oct 2020
Posts: 1,149
Likes: 265
From: The frozen wastes...
You are debating over "maybe" a couple of HP if that, for a street car which I find ridiculous. If you were racing competitively and every .01 or tenth counts, then do it if it makes you feel better, but I think this is craziness in a street car and not worth the effort or cost IMO. GL with your build and dyno pulls.
Race Director
Joined: Mar 2017
Posts: 11,953
Likes: 4,510
From: Virginia
The extra drag from the U-joints is all I can think would be the difference. The weight doesn't matter for the actual measured HP, it just takes longer to get there.
All things being equal, does a car with a lighter flywheel make more HP than one with a stock flywheel? No! But it revs faster and feels quicker.
Now that you have two cars to play with, I'm looking forward to seeing your dyno pulls to either validate or disprove my theory.
All things being equal, does a car with a lighter flywheel make more HP than one with a stock flywheel? No! But it revs faster and feels quicker.
Now that you have two cars to play with, I'm looking forward to seeing your dyno pulls to either validate or disprove my theory.
Thread Starter
Burning Brakes
Joined: Oct 2020
Posts: 1,149
Likes: 265
From: The frozen wastes...
The extra drag from the U-joints is all I can think would be the difference. The weight doesn't matter for the actual measured HP, it just takes longer to get there.
All things being equal, does a car with a lighter flywheel make more HP than one with a stock flywheel? No! But it revs faster and feels quicker.
Now that you have two cars to play with, I'm looking forward to seeing your dyno pulls to either validate or disprove my theory.
All things being equal, does a car with a lighter flywheel make more HP than one with a stock flywheel? No! But it revs faster and feels quicker.
Now that you have two cars to play with, I'm looking forward to seeing your dyno pulls to either validate or disprove my theory.
Thread Starter
Burning Brakes
Joined: Oct 2020
Posts: 1,149
Likes: 265
From: The frozen wastes...