Had my car on a Mustang dyno. Operator says that everyone leaves disapponted because the Mustang is much more conservative than Superflows, etc... (not great for repeat business eh?). Anyone have the skinny on this? BTW, a stock 2001 coupe only made 235 rwhp on this dyno :skep:

 

it was explained to me. the mustang dyno is actually more accurate. i cant remember the logistics of it all though.

i *think* it shows about 15% less, but definatly more accurate

 

Mustang Dyno = Part Throttle Tuning, less accurate peak #s
Dynojet Dyno = Full Throttle Tuning, more accurate peak #s

 

i have heard the opposite that the dyno jet is more accurate and a much better/ more expensive system that the rustang

 

Another think Jerkyboy to remember is DA will effect output numbers. My first dyno run earlier in the summer was 437.5rwhp, and later in the summer DA ~3000ft, was 399rwhp.

Sounds to me like you might have another 20hp in that combo, which porting the MAF as I said will help, But I would not expect 400+ rwhp.

Your engine builder said you only had about 9:1 compression. Which I asked him WTF would you only give him that much when aluminum heads car easily take 11:1 with zero detonation problem on 93 octane.

Corkvette only made 377rwhp, I made 399rwhp, Beachbum with his 383 (one of the best running ones here on the forum made ~360 rwhp). Know you mentioned you would like to see over 400rwhp, but I don't think that is even close to being possible. I do think we can get some more out of it with the AFR and land you at about 330rwhp, but I would say that is about max.

I did considerable Air/Fuel ratio testing on my car and the power did not waiver hardly at all on mine with major shift in extreme rich to extreme lean. It changed about 12 hp and torque changed a little bit more, but it was nothing to write home about. So I stayed with a little richer/safer Air/fuel ratio and left it at that.

Can you get me some scans of the car? From them I can tell many different things. Or like I said, come up and we can play with it in person.

:cheers:

 

This is also why nearly all dyno shop software will apply the SAE correction formulas to your numbers to bring them to a "real" figure instead of an "uncorrected" value that can and will be skewed because of DA. If you see a dyno chart w/o it being stated as SAE corrected it isn't worth using to compare to anything else.

 

Jesse. I was thinking about what you said about the heads. I was looking at that website someone here had a link to that compared head flows. The AFR 190's actually flow better that my Dart 215's from .050 to .600!!! I don't think the heads are too big. If I can figure out how to post a pic, I will scan in my dyno run with your chip showing AF. Above 2000rpm, the car is absolutely screams.

Scorp, the printout doesn't mention anything about being "SAE corrected". I might run it over to a dynojet to see if there is a diff.

 

oh yeah, When I plugged my numbers into the compression estimator on the Ross piston website, it showed over 10.5:1 compression.

 

The mustang dyno is a very good piece of equipment for tuning street cars. You can simulate real world driving conditions for tuning in all rpm ranges under a specified load, even wot. The mustang #'s are typically 9% less than dynojet #'s. I personally believe that any shop that tries to tune a street car on a dynojet is taking your money and only giving you a wot tune. Thge database on the mustang dyno is huge it creates loads for the vehicle specific wind drag, weight, etc...

 

I was under that impression too. Seems like the Mustang Dyno takes into account a lot a variables specific to the car. The operator was telling me that the computer can load up the drums to the point that the engine starts to stumble to calculate CHP.

 

jerkboy lingenfelter put a 215 cc intake head on a 420 motor i would say the 215s are not right for your combo :cheers:

 

http://www.mirageautosports.com/GTR/Dynos.html

http://www.sdsefi.com/techdyno.htm

 

just something to mention- i saw "*Dyno dynamics dynos read approx 17% less than US dyno jet dynos. These runs equte to around 500rwhp on a dynojet dyno. The runs were made 1900ft elevation." on that web site.
Elevation, humity and heat have no effect on final dyno numbers.

All numbers should be SAE corrected. non corrected numbers are worthless

 

here is a good test on the irs put in a longer bolt through the spring support go to the dyno and play with the height on the spring because that will directly transmit thorugh the drivline and change numbers accordingly since the half shafts are on different planes the straghtes plane will produce the most power the more drastic that plane is off the less power is transmitted to understand it think of a ratchet with a flex universal in the middle when it is perfect allined you have full torque applied when you go off center you lose the power transfering through that flex universal same priciples applies to our rear end setups :cheers:

 

:yesnod: That is why there is more to gain from going solid axle than just strength. :cheers:

Jerky,

Yes that is exactly right and what I was trying to convey to you about the size of the heads, 215cc heads are HUGE. And regardless of the flow rated, they are still a very large opening, larger opening slow velocity of the incoming air. In most cases though, the larger opening will flow more air, so there is a gain by going to a larger runner, however in your case. Your loosing air velocity and not gaining anything from the larger runner since it doesn't flow any better than the 190s.

That is why Corky and I spent the two months researching heads for our new combos. Plotting CFM flow numbers from about every head manufacture known. Comparing and contrasting each one against the others. It can become mind boggling. But at the end of the day you have to compile it all together and find the best one for your setup and your budget.

Heads are where the power is made or cut off.

We can definately get you some more out of the combo. As I said I would like to do it in person and give it a once over in person to make sure everything is setup perfect.

Also, the reason I said 9:1 is that is what your engine builder told me he made your compression. There are many things that enter into compression ratios. Head gasket, pistons, Heads CC, how far down in the hole the piston is ect. Maybe it is 10.5, not sure why he would tell me that then.... :confused:

Let me know that you want to do with it and I will help in any way I can.

Jesse :cheers:

 

Jesse, what is your schedule next weekend? Depending on weather, maybe I could come up there. Went to M-D on Sat. and ran 13.0 @108 blowing black smoke all the way down the track! She's running real rich in the middle, lean on top. Found out that I have the GT7 rear (3.33). This definately not helping my situation any!

 

Very simply put the two use different brake mechanisms...The Mustang is an eddy-current load dyno and the Dynojet is an inertia load dyno. The Mustang is very good for tuning street cars as was pointed out because it is capable of replicating different driving characteristics; it is not, however, as accurate on actual hp ratings. The problem is there's no standardization in ratings on chassis dynos like there is on engine dynos. I've messed with three different types of engine dynos; a SuperFlow, a Stuska, and most recently a DTS. All have standardized output ratings and all have been within a few percent of one another. I've also messed around with both the DynoJet and the Mustang chassis units (we have two DynoJets and a Mustang in the L.R. area). The Mustang has the greatest drivetrain loss discrepency of ANY chassis dyno. When I dynoed my KNOWN (by engine dyno) 396" motor on the Mustang I came away sorely disappointed until I called Mustang and they actually told me that the "typical" loss they see is in the 30% range. Before then all of my testing was done on DynoJets and they are almost without fail 15% on manual tranny cars and 18-20% on auto cars for drivetrain loss... IMO 30% is unacceptable because the losses obviously don't correspond with true numbers. The new 248C DynoJet now has software that allows loading of the dyno in a similar manner as a Mustang to replicate real world driving conditions which is nice. I prefer the DynoJet over the Mustang because its numbers (again IMO) more closely replicate those that I see on engine dynos.
-Jeb

 

30%?? wow. That means my 310hp is 403rwhp. That would be too good to be true. I am going to try a dyno jet as soon as I get a new chip. The shop that built my engine is giving me free runs on the Mustang until I get the setup correct. I should be able to report back with back to back differences with almost all being equal.

 

You said a stock C5 put 235rwhp down? They're normally in the high 280s to just a hair under 300rwhp. That could be like 33% loss depending on what tranny it was. :U

 

My motor only put down 366 rwhp on the Mustang... My engine dyno sheet (on a Stuska dyno in the engine shop I worked in) was 571 hp and 505 tq for the peaks... That figured out to more than a 35% driveline loss through a ZF which I KNEW was B.S... On a DynoJet it worked out to slightly more than 14% loss at 491 rwhp... That's a 125 hp difference between two chassis dynos! To reaffirm this further a buddy's single T72 Supra made 440 rwhp on a Mustang and 626 on a DynoJet. Is one right and one wrong? No, they just rate power differently because they load differently. You can load a Mustang to replicate DynoJet numbers, though...
-Jeb