Updated my website with a dyno results page....

[blykins]

I'll see if Gary will give me the numbers. If I remember correctly though, he wouldn't let the operator pull the engine up as high as we did on the engine dyno, so the results will be skewed. Also, the carb was set up in the car so that the linkage wouldn't let it open up all the way. Gary found it later and noted that it felt like a completely different car at WOT.

I've seen dyno numbers vary from builder to builder. I know for a fact that one engine has been dyno'd on the dyno that I use and then was taken across town to a Superflow and showed 5% higher. You'll also see builders dyno at 120 deg water temp, where I try to dyno closer to 160-170, a temp that is closer to what the car will see, but isn't hot enough to cause issues under a full load.

I also really don't agree with comparing engine dyno numbers to chassis dyno numbers, especially in a Cobra. One member here (Excalibur) stuck his car on a chassis dyno, made a pull, then removed his side pipes and made 100 more RWHP. There can not be a direct correlation when golf-ball sized pipes are used, when restrictive air cleaners are used because of hood clearance, etc. All of those things play a big part in numbers, and if the engine wasn't dyno'd in the exact same setting, then it's bogus.

[Cashburn]

Originally Posted by blykins

I'll see if Gary will give me the numbers. If I remember correctly though, he wouldn't let the operator pull the engine up as high as we did on the engine dyno, so the results will be skewed. Also, the carb was set up in the car so that the linkage wouldn't let it open up all the way. Gary found it later and noted that it felt like a completely different car at WOT.

I believe that could be due to the removal and reinstall to address the head gaskets and or the intake gasket... then again it could have simply been the stretch in the throttle cable.

The main difference in the car he mentioned to me was pulling off the dry sump.

But yeah, the chassis dyno is a world of difference in setting up the car with the engine. Too bad ours was not completely installed when Gary's car went through since it would have been good to baseline it against 40 other or so engines in the same car by different builders etc.

Keep working on the charts, it's a great resource to offer.

[DAVID GAGNARD]

Originally Posted by Cashburn

I've gotten over 100 engines dyno'ed over the years by various builders and at different dyno "shops" (primarily on Superflow) and they all have a column of corrected and uncorrected numbers for both HP and TQ. It's where the rubber meets the roller though we see the numbers with accounting for actual headers, exhaust, air cleaner, etc. in use.

I know the first engine on Brent's page has been on a chassis dyno so he has access to those numbers (and graphs, and corrected) if he wants it.

I just wanted my engine dynoed to get the most out of what I built....I brought along my headers and air filter and it was dynoed with my headers/air filter on and also my water pump on it,so it was fairly close as to how it would be in the car....the only thing not on it at the time was the alternator.....

The printouts I saw all had "STD Corrected" on them, so I just assumed that's how it's done...

I know air density/elevation plays a big part in HP... Down here in Louisiana at sea level it's one thing,other areas are another.......I used to drag race my street car a fair bit down here and one year went to Tulsa for the Shelby meet and ran it there.....I was 4/10ths off my "normal" time and asked others if saw the same thing, one big time racer said that was normal because of the elevation change....
I couldn't believe that would make that much difference, but it does....

David

[Cashburn]

Originally Posted by DAVID GAGNARD

I just wanted my engine dynoed to get the most out of what I built....I brought along my headers and air filter and it was dynoed with my headers/air filter on and also my water pump on it,so it was fairly close as to how it would be in the car....the only thing not on it at the time was the alternator.....

The printouts I saw all had "STD Corrected" on them, so I just assumed that's how it's done...

I know air density/elevation plays a big part in HP... Down here in Louisiana at sea level it's one thing,other areas are another.......I used to drag race my street car a fair bit down here and one year went to Tulsa for the Shelby meet and ran it there.....I was 4/10ths off my "normal" time and asked others if saw the same thing, one big time racer said that was normal because of the elevation change....
I couldn't believe that would make that much difference, but it does....

David

Yes sir. Exactly.

[blykins]

Originally Posted by Cashburn

I believe that could be due to the removal and reinstall to address the head gaskets and or the intake gasket... then again it could have simply been the stretch in the throttle cable.

The main difference in the car he mentioned to me was pulling off the dry sump.

But yeah, the chassis dyno is a world of difference in setting up the car with the engine. Too bad ours was not completely installed when Gary's car went through since it would have been good to baseline it against 40 other or so engines in the same car by different builders etc.

Keep working on the charts, it's a great resource to offer.

Thanks.

As long as everyone remembers that dyno numbers *should* be used as a general tuning tool, things shouldn't get out of hand. However, my intent was to just show what typical engine combos make, where they make the horsepower, etc. Its nice to be able to look and see what difference a set of heads can make, what difference a camshaft should make, etc.

And what David says holds true in every respect. It's very difficult to dyno an engine here or build a carb here and it be in perfect tune as you send it to a different region in the US.

[Cashburn]

That's why you should show the graphs, it tells more than peak etc. Take time with it and show the bigger story on a few engines. So many hours in one build, a few more minutes to convey each one.

[Jerry Clayton]

Altho graphs will show how much hp/tq was made at what rpm, sometimes you may get a graph that has a funny look to it that is the result of a time difference that actually effects the look of the line but not much the numbers.

I recently was doing an 57 chev with a gross assortment of components that as a result of the small diameter, long tube headers, and cobbled exhaust system (rump,rump,loud) and a manifold for extreme high rpm that had a slump? in the curve after the initial hit from down low (after header tune rpm) and before it got to the manifold tuned range------wasn;t something you could feel in drivability tests but the dyno did show it up----just a slight lessening of the curves but when done on a graph/chart without TIME as a basic looked weird!

[AL427SBF]

Originally Posted by Cashburn

That's why you should show the graphs, it tells more than peak etc. Take time with it and show the bigger story on a few engines. So many hours in one build, a few more minutes to convey each one.

Agree, how it gets to that "peak" cannot be understated, this guy was looking for help to smooth things out, I expect drivability would have been a challenge under any kind of acceleration.

[blown]

thanks for the info you guys are awsome i was afraid to go bigger than .560 lift on my hyd. cam but not now.

[fordracing65]

Talk to Blykins about what you want, he will guide you to the direction of the golden light...