Another Dyno Fail! - Chevelle Tech
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post #1 of 17 (permalink) Old Jun 27th, 20, 6:06 PM Thread Starter
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Steve
 
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Another Dyno Fail!

I hate chassis dyno's! Similar problems again on a different dyno. Made a partial pull to 5,760 and it made 604RWHP. This was a real quick stab at the throttle and I'm not sure if I went full throttle. My data logs are giving me errors when I try to open them. The one from the drive to the dyno worked the three on the dyno did not.

Went for a full pull to 7,200 and no data. The dyno thinks I exceeded 180MPH. The dyno owner thinks if he ends the pull early he can avoid the error. He did and we got data but he ended it at 5,900 and I ran the car to 7,200. It made 670RWHP at 5,900. These numbers are consistent with the numbers from 2 years ago, which were 640 at 5,800 and 740 at 6,200. If it gains 100RWHP in 400RPM, it could gain 250RWHP from 6,200 to 7,200. This would put it deep in the 900RWHP territory which makes sense. The tune is still real soft. I'm done with dyno's! Time to hit the track! Those are the numbers that count.
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'69 Camaro - 429 SBC Dart Iron Eagle 9.325" block, Crower crank, Crower 6" Billet rods, Ross pistons (10:1), Total Seal S/S rings, AFR 245 heads, T&D steel rockers, Cloyes Timing Set, 4-7 swap solid roller 274/286 @ .050", .704" lift, Dart single plane, Dominator EFI, Stef's #1705R pan, F2 Procharger on E85
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post #2 of 17 (permalink) Old Jun 27th, 20, 7:54 PM
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Chris
 
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Re: Another Dyno Fail!

Nothing broke so not a bad day!
Please bring someone to video you at the track!
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73 nova,3515#(all steel)Pump gas!(91octane)406ci N/A, best 1/4,1.45 '60,[email protected],10.6 @ 122.38, short shifting,NO tuning!


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post #3 of 17 (permalink) Old Jun 27th, 20, 11:59 PM
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JIM
 
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Re: Another Dyno Fail!

Looking back at some of the first pump gas Dynojet runs on my 555"...I was amazed at how much power it gained within small RPM windows. Especially at the lower end even only using around 15 psi of boost.


From 3,200 rpm to 3,700 rpm, it gains 225 rwhp.
From 3,700 rpm to 4,200 rpm, it gains another 200 rwhp.
From 4,200 rpm to 4,800 rpm, it gains another 200 rwhp.
From 4,800 rpm to 5,500 rpm, it gains another 125 rwhp.

JIM

'67 Vette-555"/Gforce 5 Spd/Dana 60 IRS-3.07's

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post #4 of 17 (permalink) Old Jun 28th, 20, 1:25 AM Thread Starter
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Re: Another Dyno Fail!

Quote:
Originally Posted by 540Hotrod View Post
Looking back at some of the first pump gas Dynojet runs on my 555"...I was amazed at how much power it gained within small RPM windows. Especially at the lower end even only using around 15 psi of boost.


From 3,200 rpm to 3,700 rpm, it gains 225 rwhp.
From 3,700 rpm to 4,200 rpm, it gains another 200 rwhp.
From 4,200 rpm to 4,800 rpm, it gains another 200 rwhp.
From 4,800 rpm to 5,500 rpm, it gains another 125 rwhp.

JIM
I was off a little bit from what it was two years ago. It doubled in HP from 5,200 to 5,900. About 330HP, and the low pull was 5,900RPM and the power was 667. That's pretty much the same as what it was today. The 6,200 pull was 740 or 750. The big Prochargers like the F2 have a really steep curve in the upper RPM's. It would be nice to find out what mine is making at 7,200 where the boost is 26 pounds. At 5,900 its at 16.
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'69 Camaro - 429 SBC Dart Iron Eagle 9.325" block, Crower crank, Crower 6" Billet rods, Ross pistons (10:1), Total Seal S/S rings, AFR 245 heads, T&D steel rockers, Cloyes Timing Set, 4-7 swap solid roller 274/286 @ .050", .704" lift, Dart single plane, Dominator EFI, Stef's #1705R pan, F2 Procharger on E85
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post #5 of 17 (permalink) Old Jun 28th, 20, 3:22 AM
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JIM
 
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Re: Another Dyno Fail!

Mine is a little different. My turbos are small and while they "hold on" well...they don't keep gaining power at the same rate at higher RPM. They light off quick on the street so they are fun. I'm scared to measure back pressure between the heads and the turbo's! LOL

JIM
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post #6 of 17 (permalink) Old Jun 28th, 20, 12:38 PM
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Re: Another Dyno Fail!

I'm sorry, but my view of dyno's is one of disdain for chassis dyno's, and complete faith and good on engine dyno's. Why? Well, engine dyno is absolutely essential to develop and test new components, and they are great at it. They are NOT final tune devices, period..

Chassis dyno's used for final tuning are just plan out in left field, useless, and make more trouble than they are worth, because they insist on way too much timing and over the moon rich jetting.

The only thing a chassis dyno seems to do is give someone that is an egotist the opportunity to bragging rights that his "package" made the highest this or that, not useful at all. I have seen way too many engines final tuned on a dyno, billions of horsepower and torque, and so weak on the low end, they didn't have enough power to back off that dyno under their own lack of power.

I have used dyno's for decades, I have my own engine dyno's, 2 of them, and they help immensely. I will never own a chassis dyno, total waste of time.
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post #7 of 17 (permalink) Old Jun 28th, 20, 5:16 PM
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Spike
 
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Re: Another Dyno Fail!

Interesting.

One method that seems to work is from The Doctors
Step-by-Step Guide to Optimizing your Ignition, by
Christopher A. Jacobs, Ph.D., E.E.




Note: do your google search and save some money.


In the second chapter he describes his method to use
a road Dynamometer, accurate to 2%. Following his
steps and method, it is repeatable.

I like what he says here, "There is so much misinformation
and even voodoo in the area of custom-tuning that it is no
wonder even the best tuners make mistakes, especially
last minute change-type mistakes (emphasis his).
Like every other competitive sport, it will be your mistakes
(emphasis his)that cost you more races than any amount of superior
performance on the part of your competitor."

He's got calculations, forms, and even Basic Programming Steps
for code you can write to automate this.

Hope it helps,

-- Spike
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post #8 of 17 (permalink) Old Jun 28th, 20, 5:27 PM
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I'm looking forward to the track results. Should be fast!
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post #9 of 17 (permalink) Old Jun 28th, 20, 7:23 PM
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Re: Another Dyno Fail!

Track results make good "chassis" dynos!
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post #10 of 17 (permalink) Old Jun 29th, 20, 9:17 AM
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Re: Another Dyno Fail!

Mr ray don't hate the dyno and say there is a problem because thar is simple not true. There are great chassis dyno and operators out there that get you very very close to what you do at the track. My guys shop has such a dyno and shop. Granted this was a custom designed mustang dyno that even today there are less the 5 we were told from mustang in the whole world. If you think it is out in left field. Well it does do 1/4 mile time. We to the same tune at the track it ran 9.728 and dyno said it should run 9.738. Dyno said 139.708mph and did 137.71. I can email the video where this is proven from the actual slip and dyno pull. This is a mustang 3500 hp 250 mph all wheel drive capable dyno. There are numerous runs like above just no video to back it up because they didn't want there info posted.

RH
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post #11 of 17 (permalink) Old Jun 29th, 20, 3:12 PM Thread Starter
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Steve
 
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Re: Another Dyno Fail!

Dyno's are definitely a useful tool. Don't get me wrong. My car was tuned on a chassis dyno but we didn't go for a peak number because the original set of pulleys would produce too much boost at high RPM and we didn't know exactly what the IAT's were. We knew they were better than what the ECU was seeing. With different pulleys to reduce the boost and the IAT sensor in a better spot I figured I would put it on a chassis dyno to see what it would read. I had no idea how difficult it was going to be. Having the same issue on two different dyno's. But the car is very very loud at high RPM full throttle. Video just doesn't do it justice.

Anyway, that was the plan while the track was closed. I never cared about peak dyno numbers, I just thought this once it would be interesting. The local track supposedly just opened up on Saturday but it was 102 degrees out. Now I just need some cooler weather. Something in the 80's would be nice.
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'69 Camaro - 429 SBC Dart Iron Eagle 9.325" block, Crower crank, Crower 6" Billet rods, Ross pistons (10:1), Total Seal S/S rings, AFR 245 heads, T&D steel rockers, Cloyes Timing Set, 4-7 swap solid roller 274/286 @ .050", .704" lift, Dart single plane, Dominator EFI, Stef's #1705R pan, F2 Procharger on E85
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post #12 of 17 (permalink) Old Jun 29th, 20, 3:53 PM
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Re: Another Dyno Fail!

Yep...I've lived on engine dyno's for at least 30 years. I've also used chassis dyno's. It's a little easier because my cars have stick transmissions so I don't get the converter flair-up. My current engine has been on engine dyno's at least 5 times I can think of with various combos where we swapped heads, cams, intakes etc. The current version with turbo's was done on a chassis one because I configured the engine first (cam and compression changes) then put it in the car to build the turbo mounts/plumbing etc. Much easier to take to a chassis dyno to make sure it can handle full power and work out the base tunes and try a few things. Turned out we were pretty conservative on the dyno. When I took it to the track....the addition of 3* more timing picked up 9 MPH!!!

Good news is the track times have matched what the dyno predicted. Folks just need to learn to use a dyno as a tool...not the be all- end all goal.

JIM

'67 Vette-555"/Gforce 5 Spd/Dana 60 IRS-3.07's

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post #13 of 17 (permalink) Old Jun 29th, 20, 5:48 PM
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Re: Another Dyno Fail!

Quote:
Originally Posted by Steve69SS396 View Post
I'm done with dyno's! Time to hit the track! Those are the numbers that count.
Exactly. I cannot say how many times guys walked up to me saying that their engines made 600Hp, 700HP, 800HP... yeah sure... and then they make a pass down the track and run mid 12's... Nevermind that dyno bulls**t... I've never put my car on a dyno because to me, they're good for bragging rights, but no more. On the other hand, a good time slip doesn't lie.

Claude.
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post #14 of 17 (permalink) Old Jun 29th, 20, 11:04 PM
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Use to work at a shop with a Dynojet. He always said the dyno is only a tool. He tuned mainly Ford's but ran everything that came throught the door. Funnest job I've ever had.
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post #15 of 17 (permalink) Old Jun 30th, 20, 1:05 AM
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Re: Another Dyno Fail!

Respectfully, I couldn't disagree more on the chasis dyno comments.

My experience with a local Mustang chasis dyno was some of the best time and money I ever spent.

The chasis dyno more closely resembles the "scientific process" than does going to the track, IMHO.....which is also very fun, just in a different way.

The chasis dyno eliminates driver error/technique and changing weather at the track.

Your chasis dyno results can also be corrected to a known standard.

A poser or wannabe can be just as easily be exposed on the chasis dyno as on the strip.

Basically, the chasis dyno....with a competent operator...eliminates a lot of variables and unknowns. Most street cars also run better/smoother when they leave the chasis dyno.

For us carb guys, I firmly believe a good dyno operator will give you the best AFR curve.....much better than an AFR gauge, the butt dyno, or your trap speed and 60 foot time.

To me, the most efficient thing to do after a new motor install is to break the motor in, go to the chasis dyno, and then hit the strip.

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