Re: crazy looking dyno sheet
[Re: BIGSTROKER]
#2911942
04/19/21 01:41 PM
04/19/21 01:41 PM
|
Joined: Aug 2003
Posts: 43,223 Bend,OR USA
Cab_Burge
I Win
|
I Win
Joined: Aug 2003
Posts: 43,223
Bend,OR USA
|
is the intake a eddy dual plane? If so they have a inherent low peak HP RPM limit due to the manifold being designed for stock muscle cars back in 1968 I built a pump gas low deck stroker motor (505 C.I.) with a low deck Eddy intake and 1970 440 carbs, it made peak HP at 5500 RPM and peak torque at 4500 RPM the first time I dyno tested it. I ended up swapping the heads and cranks shaft to improve the compression ratio and it made peak HP at 5600 RPM and peak torque at 4600 RPM I've been racing and winning with Mopars since 1964, I started on a very low budget and ended up assembling all my motors, that stupid six pack motor would make the car run the quickest and fastest by shifting it at or above 7000 RPM Drive it first and see what yours does by shifting it at 5000, then 5500, then at 6000 and above until you find out what your motor likes on the shift RPM Dyno sheets are one thing that these stupid motors can't read Good luck
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
|
|
|
Re: crazy looking dyno sheet
[Re: BIGSTROKER]
#2911943
04/19/21 01:42 PM
04/19/21 01:42 PM
|
Joined: Jan 2003
Posts: 10,032 MN
JERICOGTX
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 10,032
MN
|
Looks like a hiccup at 4300. When was the last time the dyno was calibrated?
69 GTX
68 Road Runner
|
|
|
Re: crazy looking dyno sheet
[Re: JERICOGTX]
#2911955
04/19/21 02:23 PM
04/19/21 02:23 PM
|
Joined: Jan 2003
Posts: 14,506 So. Burlington, Vt.
fast68plymouth
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 14,506
So. Burlington, Vt.
|
Starts out good for the first few lines, then falls on its face.
It’s down 75-100 tq & hp(if running adequately sized headers)
Is it the dyno or the induction? Or something else altogether?
It’s not using much fuel...... which kinda goes along with the low output.
Here’s a 505, Stage 1 RPM heads, 252/260-112 SFT caml, 2-2 1/8 headers...... also a 6bbl on an Ede manifold.
From 5000-up, the fuel flow was 240’s-250’s-260’s..... with it topping out at 266@6000. It was in the 220’s by 4700(you’re barely over 220@5700).
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
|
|
|
Re: crazy looking dyno sheet
[Re: fast68plymouth]
#2911966
04/19/21 02:54 PM
04/19/21 02:54 PM
|
Joined: Jan 2003
Posts: 14,506 So. Burlington, Vt.
fast68plymouth
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 14,506
So. Burlington, Vt.
|
Does that dyno service have a good reputation for accurate, and maybe even more importantly, repeatable numbers?
If you’re interested in getting to the bottom of it, “what I would do” is see if you can borrow a fairly decent single 4bbl manifold and a good working 850 or 950 carb and retest it.
Bring that 6bbl with you to the dyno, and if the power curve looks better, and the numbers are more in line with what the motor “should” be making for power...... you can reinstall it and start chasing the tune.
If the shape of the curve, and the numbers are similarly low with the single 4bbl on the motor....... there is something else going on.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
|
|
|
Re: crazy looking dyno sheet
[Re: BIGSTROKER]
#2912058
04/19/21 06:50 PM
04/19/21 06:50 PM
|
Joined: Oct 2006
Posts: 1,264 New York, USA
Chargerfan68
pro stock
|
pro stock
Joined: Oct 2006
Posts: 1,264
New York, USA
|
Here is one we tested recently just for another comparison. 505”, TF240’s, stock iron 6barrel intake, comp Hyd Roller around .580”. 10.9:1.
1.50 60Ft. , 10.75@ 127MPH Hauling 3900 LBS.
|
|
|
Re: crazy looking dyno sheet
[Re: J_BODY]
#2912150
04/20/21 12:14 AM
04/20/21 12:14 AM
|
Joined: Feb 2008
Posts: 715 Central TEXAS!!!!
sr4440
super stock
|
super stock
Joined: Feb 2008
Posts: 715
Central TEXAS!!!!
|
If i seen a drop like that 300 rpm after peak torque, i would suspect that you had a tiny bit of detonation. Some dyno's are super sensitive to detonation because of the water valve configuration.
I will say those BSFC numbers are weird as hell, usually the engine is most efficient at peak torque, your numbers don't make any sense. Did you have any afr numbers?
Joe
Without Data, you’re just another guy with an opinion.
|
|
|
Re: crazy looking dyno sheet
[Re: BIGSTROKER]
#2912196
04/20/21 09:05 AM
04/20/21 09:05 AM
|
Joined: Jan 2003
Posts: 10,732 North Dakota
6PakBee
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 10,732
North Dakota
|
I think it's odd that up to 3600 fuel flow was increasing with RPM and torque as it should. Then starting at 3700 it dropped to a low at 4100 and then recovered such that at 4300 you had the same fuel flow as 3600. It then began increasing again. So, how can you have an increase in RPM, with lower fuel flow and torque? The only explanation I can come up with is that the dyno didn't load the motor up in that RPM range. Did you do more pulls? If so, how do they compare?
"We live in a time when intelligent people are being silenced so that stupid people won't be offended".
|
|
|
Re: crazy looking dyno sheet
[Re: BIGSTROKER]
#2912231
04/20/21 11:07 AM
04/20/21 11:07 AM
|
Joined: Jan 2003
Posts: 14,506 So. Burlington, Vt.
fast68plymouth
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 14,506
So. Burlington, Vt.
|
I think I am going to install in the vehicle and test and tune that way I know everything is good mechanically so it is all about the tune at this point Personally, I’d much prefer trying to sort out a 6bbl/tuning issue on the dyno(where the results of a change are instantly quantifiable) than try to do it with all the other added variables that go along with what happens at the track. But that’s just me. Was it tested with headers on it? Will it be run in the car with headers? If it had headers on it, regardless of the shape of the curve........the power numbers seem really low.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
|
|
|
|
|