Dyno results.. - Page 2

razerwire · #1 (**permalink**) 07-28-2009, 07:05 PM

Just returned from Las Vegas, went to Kroyer to check engine tune because I thought the engine was running hotter than normally. I can say I was more than a little nervous to see my car all strapped down to get checked out. Kroyer uses a SuperFlow dyno. Runs were made to check part throttle, full throttle and all between. Power runs were held to 6000 r.p.m. Best was 460 tq at 4600 r.p.m and 490 hp at 6000 rpm and still pulling. It was nerve racking to listen to test, I thought engine was hitting 10000 r.p.m untill I went inside and could watch screen. Car runs even better and it run good before. Would recommend to get the most out of your car to do it.

Got the Bug · #2 (**permalink**) 07-28-2009, 09:44 PM

Keith - Thanks for providing your expertise regarding engine and chassis dyno testing. It's great to have a top notch vendor that stays close to the discussions within CC.

patrickt · #3 (**permalink**) 07-29-2009, 05:40 AM

I can just imagine what a PITA it is dealing with well-heeled, but basically ignorant, Cobra owners who complain that their 600HP engine just dynoed at the local Esso at 350HP.

Come to think of it, it would be a PITA dealing with Cobra owners on just about anything that is car-related....

Ital-cobra · #4 (**permalink**) 07-29-2009, 06:27 AM

Hi all

Is it the size of the size pipe that robs the HP?

Rickd · #5 (**permalink**) 07-29-2009, 07:25 AM

My KC 331 stroker, with AFR 165's, dyno'd 436 HP at 6000 rpm at KC's shop on the stand, and on a chassis dyno in Ft. Lauderdale it did 326 rwhp at 6000 rpm. Very much in line. I have side pipes. It is a 'strong' little motor, and a great combo for my FIA. Tremendous power to weight ratio.

patrickt · #6 (**permalink**) 07-29-2009, 07:41 AM

Quote:

Originally Posted by Rickd

My KC 331 stroker, with AFR 165's, dyno'd 436 HP at 6000 rpm at KC's shop on the stand, and on a chassis dyno in Ft. Lauderdale it did 326 rwhp at 6000 rpm. Very much in line.

That's way better than just being "in line." That equates to only a 50HP loss from the pipes and a mere 15% drive train loss. Of course, that assumes both dynos are correct.

Slick61 · #7 (**permalink**) 07-29-2009, 09:23 AM

Yep, with sidepipes & IRS my KCR aluminum 427 stroker put down 612 hp on the engine dyno, & 458 hp at the wheels... sounds about right.

patrickt · #8 (**permalink**) 07-29-2009, 09:40 AM

Quote:

Originally Posted by Slick61

Yep, with sidepipes & IRS my KCR aluminum 427 stroker put down 612 hp on the engine dyno, & 458 hp at the wheels... sounds about right.

That's pretty serious horsepower. Do you find that the traction issues take away from the drivability?

trularin · #9 (**permalink**) 07-29-2009, 09:56 AM

Pat, are you starting up the BB versus SB thingy...again??

patrickt · #10 (**permalink**) 07-29-2009, 10:08 AM

Quote:

Originally Posted by trularin

Pat, are you starting up the BB versus SB thingy...again??

What? Me provoke? Never.

Seriously though, 460HP at the rear wheels, I just wonder if it kicks and bucks and snots at you when you try and give it a little throttle and then when you do it busts its rear wheels loose and you're unexpectedly looking at the guy behind you.

trularin · #11 (**permalink**) 07-29-2009, 10:38 AM

What? Me imply such a thing...never.

Isn't that part of the fun? You never really know where you are going to land.

greg schroeder · #12 (**permalink**) 07-29-2009, 12:14 PM

Just take the car to the drag strip and get a trap speed.

MPH doesn't change much regardless of your time. Time is more related to how well you start rather than power.

Use the weight of your car and mph to calculate your power. Correct the numbers to sea level and you have a reasonable comparison to others or your own car on diffrent days or after changes.

http://www.prosystemsracing.com/calculate.html

http://www.modulardepot.com/density.php

ItBites · #13 (**permalink**) 07-29-2009, 12:10 PM

Mine dyno'd 540 rwhp on a fluid (not inertia) chassis dynamometer. The build on my pump-gas, street 540 cid engine should have produced about 675hp at the crank. I have IRS and an automatic transmission.

Assuming 20%loss in the trans and IRS, 675 crank hp equates exactly to 540rwhp. I think 20% loss is a pretty good number for Cobras.

BTW, I custom built equal length (34" primaries) headers with merge collectors. I think a good exhaust is crucial.

Also, good tires really help the traction issue. The cheapest way to improving your car's ACTUAL performance is to shoe it with the best rubber you can buy. I run Toyo R888s, and lower the pressure.

olddog · #14 (**permalink**) 07-30-2009, 08:37 PM

It would seem to me that side pipes robbing Hp is like the government taxing income. The more you have the bigger percentage they will take.

I doubt 200 Hp measured on an engine dyno would suffer much loss with relatively open side pipes, but a 600 Hp engine through the same pipes would get killed.

Not that I am trying to argue less power is more. Just that the amount of losses most likely increases exponentially, as you build more power. Certainly there is a point of diminishing returns, not that I am smart enough to tell anyone where that is at.

patrickt · #15 (**permalink**) 07-30-2009, 08:46 PM

Quote:

Originally Posted by olddog

It would seem to me that side pipes robbing Hp is like the government taxing income. The more you have the bigger percentage they will take.

I think you're right. Plus, on my pipes, I had Stainless Specialties make them a little "more quiet." That most assuredly robs more horsepower, but it makes the car a little more pleasant to drive. Maybe it's my imagination but I'd swear that my car has gotten a little quieter over the last couple of years. Either that or I just don't notice it as much or I'm losing my hearing.