Previous Thread
Next Thread
Print Thread
Page 2 of 7 1 2 3 4 5 6 7
Re: Unexpected Dyno Results [Re: MarkZ] #2527204
07/26/18 01:10 AM
07/26/18 01:10 AM
Joined: Jun 2006
Posts: 5,155
CT
GTX MATT Offline
master
GTX MATT  Offline
master

Joined: Jun 2006
Posts: 5,155
CT
As mentioned, chassis dynos and automatics can produce strange results, especially with a loose converter.

Looks to me like your converter slipped to around 5300 RPM, where both curves hook, and your TQ and HP were already falling off. I think its very unlikely that engine peaks torque at 5300 RPM.

What exactly is the converter? According to TA that converter is for a late model Hemi or Magnum setup... if this is the correct converter its going to stall way higher than it is designed to stall behind a 318-360 cubic inch engine.


Now I need to pin those needles, got to feel that heat
Hear my motor screamin while I'm tearin up the street
Re: Unexpected Dyno Results [Re: MarkZ] #2527209
07/26/18 01:19 AM
07/26/18 01:19 AM
Joined: Jan 2003
Posts: 14,479
So. Burlington, Vt.
F
fast68plymouth Offline
I Live Here
fast68plymouth  Offline
I Live Here
F

Joined: Jan 2003
Posts: 14,479
So. Burlington, Vt.
Tq and hp are always exactly the same, and cross paths at 5252rpm.


68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads
Re: Unexpected Dyno Results [Re: MarkZ] #2527232
07/26/18 03:07 AM
07/26/18 03:07 AM
Joined: Jan 2003
Posts: 30,947
Oregon
A
AndyF Offline
I Win
AndyF  Offline
I Win
A

Joined: Jan 2003
Posts: 30,947
Oregon
I think you have a great combo for the street. Get out there and enjoy it this summer and then decide if you really want to change it. A bigger cam will make more peak power but you might lose some low end torque. Drive it for a while to see what you think before you make up your mind. You might just like the smooth idle and bottom end grunt that you get with a smaller cam.

Re: Unexpected Dyno Results [Re: MarkZ] #2527279
07/26/18 11:02 AM
07/26/18 11:02 AM
Joined: Jun 2008
Posts: 3,913
usa
L
lewtot184 Offline
master
lewtot184  Offline
master
L

Joined: Jun 2008
Posts: 3,913
usa
with this combo I would be cautious about over gearing and too loose of a converter. on an engine dyno this engine may show close to 550hp. i'd try to sneak up on the total timing some; maybe try 36-37 degrees. you can get 2 1/2" mufflers that will flow better than some 3". I wouldn't get lost in the peak horsepower/rpm thing. whatever gains you might be making above 5200rpm may be ate up driving the trans/axle. chassis dyno thing is a different world than the more common engine dyno numbers. in my opinion, chassis dyno is real world and engine dyno can be more pie in the sky.

Re: Unexpected Dyno Results [Re: MarkZ] #2527309
07/26/18 12:09 PM
07/26/18 12:09 PM
Joined: Jan 2008
Posts: 1,206
Minn
S
SportF Offline
pro stock
SportF  Offline
pro stock
S

Joined: Jan 2008
Posts: 1,206
Minn
Why is everybody afraid to try and put some timing in it? Is it an internet myth or something?

Re: Unexpected Dyno Results [Re: SportF] #2527379
07/26/18 02:21 PM
07/26/18 02:21 PM
Joined: Aug 2003
Posts: 43,007
Bend,OR USA
C
Cab_Burge Offline
I Win
Cab_Burge  Offline
I Win
C

Joined: Aug 2003
Posts: 43,007
Bend,OR USA
I've tested BB ignition timing many at the track and on multiple race gas and pump gas engines on a engine dyno, all of the ones I tested like between 34 and 36 BTDC total timing for the best ET, MPH and HP and torque on the dyno.
This is with the TDC verified to make sure zero on the timing tab and balancer where accurate, I have found many engines that they where off also shock work
I raced a 1963 415 HP Max Wedge car in NHRA stock for many years, a friend and fellow SS racer had a 1963 Savoy 415 M.W. he raced in Super Stock and swore his motor liked 42 degrees total timing shruggy I learned later he didn't build his motors and it had a late model timing cover with a early dampener, which ends up indicating 10 degree more timing than actual work shruggy
IHTHs up


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: Unexpected Dyno Results [Re: MarkZ] #2527395
07/26/18 02:35 PM
07/26/18 02:35 PM
Joined: Jan 2003
Posts: 14,479
So. Burlington, Vt.
F
fast68plymouth Offline
I Live Here
fast68plymouth  Offline
I Live Here
F

Joined: Jan 2003
Posts: 14,479
So. Burlington, Vt.
Here’s that one from last fall, with a 2” super sucker on it:

B4033693-227F-4C4B-BC0D-023E58CD13A6.jpeg

68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads
Re: Unexpected Dyno Results [Re: MarkZ] #2527400
07/26/18 02:40 PM
07/26/18 02:40 PM
Joined: Dec 2005
Posts: 1,494
Shelby mi.
J
JAKE68 Offline
pro stock
JAKE68  Offline
pro stock
J

Joined: Dec 2005
Posts: 1,494
Shelby mi.
Pulling up his runs out and doing the conversion to mph and looking at comparing to rpm and doing the math this thing is just blowing threw converter. looking at the graft you can see it is trying to couple up then it finally does when it starts running out of power.


JAKES AUTOMOTIVE
Re: Unexpected Dyno Results [Re: JAKE68] #2527534
07/26/18 07:21 PM
07/26/18 07:21 PM
Joined: Jan 2003
Posts: 30,947
Oregon
A
AndyF Offline
I Win
AndyF  Offline
I Win
A

Joined: Jan 2003
Posts: 30,947
Oregon
Does the dyno have the ability to plot drum RPM vs. engine RPM? That would probably show what is going on.

Re: Unexpected Dyno Results [Re: MarkZ] #2527537
07/26/18 07:28 PM
07/26/18 07:28 PM
Joined: Dec 2005
Posts: 1,494
Shelby mi.
J
JAKE68 Offline
pro stock
JAKE68  Offline
pro stock
J

Joined: Dec 2005
Posts: 1,494
Shelby mi.
Andy that's basically what we did and came up with the results. I didn't know how to do that so when my dyno operator came in and he did it and showed me.


JAKES AUTOMOTIVE
Re: Unexpected Dyno Results [Re: JAKE68] #2527571
07/26/18 08:30 PM
07/26/18 08:30 PM
Joined: Jan 2003
Posts: 30,947
Oregon
A
AndyF Offline
I Win
AndyF  Offline
I Win
A

Joined: Jan 2003
Posts: 30,947
Oregon
So just to take a guess, at 3000 engine rpm the drum is barely moving. Since the drum is barely moving the recorded HP is low, but really the engine is making a bunch of power. It is just the that engine power is being absorbed by the torque converter (turned to heat in the tranny fluid) rather than turning the drum.

If that is what is going on then he needs a much tighter converter. Maybe a stock Hemi converter or something even stouter like a truck converter. With 500 inches and a small cam there is going to be a lot of torque on hand right off idle.

Re: Unexpected Dyno Results [Re: MarkZ] #2527574
07/26/18 08:41 PM
07/26/18 08:41 PM
Joined: Dec 2005
Posts: 1,494
Shelby mi.
J
JAKE68 Offline
pro stock
JAKE68  Offline
pro stock
J

Joined: Dec 2005
Posts: 1,494
Shelby mi.
I don't think that that converter was designed for that much torque and it would not couple up. I would think that it just needs a converter more designed for that application and not one that was met for a small block. he probably could still get by with something that would be in the 3200-3800 rpm.


JAKES AUTOMOTIVE
Re: Unexpected Dyno Results [Re: MarkZ] #2527579
07/26/18 08:51 PM
07/26/18 08:51 PM
Joined: Jan 2003
Posts: 14,479
So. Burlington, Vt.
F
fast68plymouth Offline
I Live Here
fast68plymouth  Offline
I Live Here
F

Joined: Jan 2003
Posts: 14,479
So. Burlington, Vt.
AFAIK, the dynojet doesn’t have any load cell to “take a reading” and measure torque.
It uses a formula to calculate the speed differential over time, and calculates how much power it takes to accelerate the drum(which has a known mass) that amount, in that amount of time(not a good description I know).
Basically, the rate of acceleration is what’s used to calculate the power.
It’s an inertia dyno.

If you run two cars with noticeably different power levels, say 100hp and 800hp, through the same rpm range(like 2500-6500), you’d notice the lower power car took much longer to get from 2500-6500.
The only thing controlling the “rate” is the weight of the drums and the output of the motor.
More power accelerates the drum faster.

I’m not sure all dyno jets operate this way, but the one my friends have does.

Edit: I did a little search and it appears Dynojet does offer some of their dynos with eddy current loading, along with the inertia loading.
With eddy current loading, it would be capable of taking an actual torque reading.


68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads
Re: Unexpected Dyno Results [Re: MarkZ] #2527582
07/26/18 08:52 PM
07/26/18 08:52 PM
Joined: Oct 2007
Posts: 4,205
New York
polyspheric Offline
master
polyspheric  Offline
master

Joined: Oct 2007
Posts: 4,205
New York
Something is wrong.
Not only are the numbers disappointing, the torque curve should NEVER have a big spike like that.


Boffin Emeritus
Re: Unexpected Dyno Results [Re: fast68plymouth] #2527587
07/26/18 09:01 PM
07/26/18 09:01 PM
Joined: Aug 2011
Posts: 2,843
Pattison Texas
CSK Offline
master
CSK  Offline
master

Joined: Aug 2011
Posts: 2,843
Pattison Texas
Originally Posted By fast68plymouth
AFAIK, the dyno jet doesn’t have any load cell to “take a reading” and measure torque.
It uses a formula to calculate the speed differential over time, and calculates how much power it takes to accelerate the drum(which has a known mass) that amount, in that amount of time(not a good description I know).
Basically, the rate of acceleration is what’s used to calculate the power.

If you run two cars with noticeably different power levels, say 100hp and 800hp, through the same rpm range(like 2500-6500), you’d notice the lower power car took much longer to get from 2500-6500.
The only thing controlling the “rate” is the weight of the drums and the output of the motor.
More power accelerates the drum faster.

I’m not sure all dyno jets operate this way, but the one my friends have does.


You are correct. they do have a load cell option but I have never seen one, every one I have used & seen was just the drum.

Last edited by csk; 07/26/18 09:02 PM.

1968 Charger COLD A/C Hilborn EFI
512ci 9.7 compression, Stealth heads, 4.10 gear A518 ODtrans 4100lb,10.93 full street car trim
2020 T/A 392 Stock 11.79 @ 114.5

Re: Unexpected Dyno Results [Re: MarkZ] #2527593
07/26/18 09:10 PM
07/26/18 09:10 PM
Joined: Jan 2003
Posts: 14,479
So. Burlington, Vt.
F
fast68plymouth Offline
I Live Here
fast68plymouth  Offline
I Live Here
F

Joined: Jan 2003
Posts: 14,479
So. Burlington, Vt.
I know of a few cars that got run over at my friends shop where the numbers just didn’t make sense(weren’t right).

One that comes to mind was a 69 charger with a 446. Rpm heads, 509 cam, headers, 850 demon carb, 3.91’s, 10” converter.
It was something silly like 285hp.
The car actually ran pretty good on the street. This was an all steel, full interior street car.
Had to weigh at least 3800 with driver.

Went high 11’s at the track.

That’s not 285rwhp doing that.


68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads
Re: Unexpected Dyno Results [Re: MarkZ] #2527781
07/27/18 10:39 AM
07/27/18 10:39 AM
Joined: Jan 2003
Posts: 13,319
Marion, South Carolina [><]
an8sec70cuda Offline
I Live Here
an8sec70cuda  Offline
I Live Here

Joined: Jan 2003
Posts: 13,319
Marion, South Carolina [><]
FWIW...my cuda made 636 hp and 555 ft lbs of torque on the local Dynojet.
Ran 9.54 at 140.4 mph at 3800 lbs in that configuration.

Outran a bunch of supposed 800+ hp at the wheels cars too.


CHIP
'70 hemicuda, 575" Hemi, 727, Dana 60
'69 road runner, 440-6, 18 spline 4 speed, Dana 60
'71 Demon, 340, low gear 904, 8.75
'73 Chrysler New Yorker, 440, 727, 8.75
'90 Chevy 454SS Silverado, 476" BBC, TH400, 14 bolt
'06 GMC 2500HD LBZ Duramax
Re: Unexpected Dyno Results [Re: MarkZ] #2527786
07/27/18 10:48 AM
07/27/18 10:48 AM
Joined: Oct 2015
Posts: 570
UK
rb446 Offline
mopar
rb446  Offline
mopar

Joined: Oct 2015
Posts: 570
UK
866Fwhp

60 Foot E.T. : 1.33
1/8 Mile E.T. : 6.02
1/8 Mile Trap Speed : 112.96
1/4 Mile E.T. : 9.54
1/4 Mile Trap Speed : 140

up


1969 'Cuda 446ci, best 9.96@133.9 in 1990
1971 340 'Cuda, best 11.01@122.8 in 1987
Re: Unexpected Dyno Results [Re: rb446] #2527787
07/27/18 10:50 AM
07/27/18 10:50 AM
Joined: Jan 2003
Posts: 13,319
Marion, South Carolina [><]
an8sec70cuda Offline
I Live Here
an8sec70cuda  Offline
I Live Here

Joined: Jan 2003
Posts: 13,319
Marion, South Carolina [><]
Originally Posted By rb446
866Fwhp

60 Foot E.T. : 1.33
1/8 Mile E.T. : 6.02
1/8 Mile Trap Speed : 112.96
1/4 Mile E.T. : 9.54
1/4 Mile Trap Speed : 140

up

up It actually went 1.320 to the 60' and 6.05 at 112.9 to the 1/8. Your calculations look good to me, lol. Always figured it was in the 850 hp range.


CHIP
'70 hemicuda, 575" Hemi, 727, Dana 60
'69 road runner, 440-6, 18 spline 4 speed, Dana 60
'71 Demon, 340, low gear 904, 8.75
'73 Chrysler New Yorker, 440, 727, 8.75
'90 Chevy 454SS Silverado, 476" BBC, TH400, 14 bolt
'06 GMC 2500HD LBZ Duramax
Re: Unexpected Dyno Results [Re: MarkZ] #2527791
07/27/18 10:56 AM
07/27/18 10:56 AM
Joined: Oct 2015
Posts: 570
UK
rb446 Offline
mopar
rb446  Offline
mopar

Joined: Oct 2015
Posts: 570
UK
Wallace calc, but only 1 of them, been using it for years, has been pretty accurate for my old cars and others....Moroso chart differs, less hp etc.

http://www.wallaceracing.com/accel-calc.php

Input weight and then adjust hp no.

Last edited by rb446; 07/27/18 10:57 AM.

1969 'Cuda 446ci, best 9.96@133.9 in 1990
1971 340 'Cuda, best 11.01@122.8 in 1987
Page 2 of 7 1 2 3 4 5 6 7






Powered by UBB.threads™ PHP Forum Software 7.7.1