FAQ |
Members List |
Social Groups |
Calendar |
Search |
Today's Posts |
#21
|
||||
|
||||
My duramax has a big spread like that. I've never seen a gas engine do that.
|
#22
|
||||
|
||||
Quote:
You need to understand how that type of dyno works. Rear end gear ratio and rear tire size should make no difference. Normally the test is done in drive 1:1. I talk with someone who did the test in both 2nd and 3rd gear and it made also no difference. In some cases they use a fixed amount for tire to crank and other places do a coast down to try to measure the drive train losses. Stan
__________________
Stan Weiss/World Wide Enterprises Offering Performance Software Since 1987 http://www.magneticlynx.com/carfor/carfor.htm David Vizard & Stan Weiss' IOP / Flow / Induction Optimization - Cam Selection Software http://www.magneticlynx.com/DV Download FREE 14 Trial IOP / Flow Software http://www.magneticlynx.com/DV/Flow_..._Day_Trial.php Pontiac Pump Gas List http://www.magneticlynx.com/carfor/pont_gas.htm Using PMD Block and Heads List http://www.magneticlynx.com/carfor/pont_pmd.htm |
#23
|
||||
|
||||
Ok got,and thanks for waking me up this morning Stan, but still something is off with those results.
__________________
Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
#24
|
||||
|
||||
Ok so sorry for the confusion but like I said that is the first dyno sheet I’ve seen. Talked to the mechanic and he explained to me what’s going on. The torque numbers are indeed wrong on that sheet. He told me some of the differences between a mustang dyno and a “dyno jet ?” machine and how they work. He is standing by the HP numbers though. Sorry if that upsets some of you.
__________________
1981 Trans Am project -YJ 400 stroked to 488 CID-74cc Eheads-10.95:1-Northwind Intake-Holley Terminator-TH400-Moser rear-Dougs Headers.... |
#25
|
|||
|
|||
Do you have the dyno sheet with your 3.55 gears in the car?
Paul Spotts built my engine. His shop is a half hour away from my house. I use 2nd Street Speed in Perkadie for my dyno work. |
#26
|
||||
|
||||
No I just swapped the gears this summer and I am still dialing in the tune. I probably won’t do it again though because of the cost and I don’t think the numbers would change much. I am also not overly concerned with the exact figures. The car has plenty of power for me, but everyone wonders what their car could do at the track.
__________________
1981 Trans Am project -YJ 400 stroked to 488 CID-74cc Eheads-10.95:1-Northwind Intake-Holley Terminator-TH400-Moser rear-Dougs Headers.... |
#27
|
|||
|
|||
printout shows 568.5 crankshaft horsepower with the Correction Factor, which is believable, nothing unusual there. I'm unsure of what the rpm of 2950 is measuring, I would expect the horsepower peak in the 5200-5500 engine rpm range. I would think torque to be in the 600-625 range on this 4.5" stroke engine.
Would need more info on car to estimate track times
__________________
66 GTO, 495, M22, Strange S-60 w/4.10 Sold new at Royal Pontiac. 70 Formula |
#28
|
|||
|
|||
What's the difference between a Mustang dyno and a dynojet?
Opinions........... http://forums.mustangworks.com/f12/d...-dynojet-9929/ .
__________________
'70 TA / 505 cid / same engine but revised ( previous best 10.63 at 127.05 ) Old information here: http://www.hotrod.com/articles/0712p...tiac-trans-am/ Sponsor of the world's fastest Pontiac powered Ford Fairmont (engine) 5.14 at 140 mph (1/8 mile) , true 10.5 tire, stock type suspension https://www.youtube.com/watch?v=qDoJnIP3HgE |
#29
|
||||
|
||||
The car is pretty much an unmodified 81 firebird. I think the original curb weight was almost 3400lbs. I have aluminum heads, intake, and wheels so it’s still over 3000 easy. Th400 trans, Holley efi, dennys driveshaft, moser 3:55 rear. 275/40/18 rear tires. What else do you need ? I do have adjustable shocks but no drag tires. Headers, 2.5” exhaust, and turbo muffs
I was told one of the differences with the mustang dyno is that it puts a load on the engine while testing while the dyno jet does not which could result in as much as a 10% difference in readings.
__________________
1981 Trans Am project -YJ 400 stroked to 488 CID-74cc Eheads-10.95:1-Northwind Intake-Holley Terminator-TH400-Moser rear-Dougs Headers.... |
#30
|
||||
|
||||
568 corrected flywheel hp i believe.
__________________
Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
#31
|
|||
|
|||
Chassis dyno. Even from dyno to dyno of the same make/brand differences can vary.
In the end, it's a "tuning tool" more than anything else. It would be interesting to know at what RPM peak power was made and at what RPM was peak torque. On our 4.5" stroke engine the RPM difference between peak power and peak torque was around 1600 rpm. Tested on a engine dyno. Smackdown: Engine Dyno vs. Chassis Dyno https://www.motortrend.com/articles/...chassis-dynos/ .
__________________
'70 TA / 505 cid / same engine but revised ( previous best 10.63 at 127.05 ) Old information here: http://www.hotrod.com/articles/0712p...tiac-trans-am/ Sponsor of the world's fastest Pontiac powered Ford Fairmont (engine) 5.14 at 140 mph (1/8 mile) , true 10.5 tire, stock type suspension https://www.youtube.com/watch?v=qDoJnIP3HgE |
#32
|
|||
|
|||
Here this 488-inch 4.5" stroke Pontiac made peak torque at 4100 RPM and peak power at 5500 RPM. The spread between the two was 1400 RPM.
592 hp and 625 lb-ft of Torque. https://www.motortrend.com/how-to/48...e1B6OEcjx2OCD4 .
__________________
'70 TA / 505 cid / same engine but revised ( previous best 10.63 at 127.05 ) Old information here: http://www.hotrod.com/articles/0712p...tiac-trans-am/ Sponsor of the world's fastest Pontiac powered Ford Fairmont (engine) 5.14 at 140 mph (1/8 mile) , true 10.5 tire, stock type suspension https://www.youtube.com/watch?v=qDoJnIP3HgE |
#33
|
|||
|
|||
Quote:
You put it out there like your engine is making so much unbelievable power it upsets people. Its not a standard dyno sheet so people have questions. Seems like its a nice solid street engine that makes around 560 HP, nothing wrong with that. But no street Pontiac is putting out 887 lbs torque, much less 1200. And that thing has got to weigh way more than 3400 lbs in street trim. Those cars are heavy. |
#34
|
||||
|
||||
Quote:
__________________
1981 Trans Am project -YJ 400 stroked to 488 CID-74cc Eheads-10.95:1-Northwind Intake-Holley Terminator-TH400-Moser rear-Dougs Headers.... |
Reply |
|
|