Final dyno runs
10-12-2006, 05:16 PM
#1
Race Director
Thread Starter
Final dyno runs
Engine 327 stock, ~11:1 pistons, L-46 cam, Early Bow-Tie heads, 1.62" primary diameter off the shelf Hedman headers, full length exhaust. EFI on Edelbrock Victor Jr. manifold. Approx 50,000 miles on the engine.
The first chart shows the best run of today, with the best *as driven* run of one month ago.
In between, I recalibrated the timing and fuel,and today we tweaked the timing and fuel.
The original run of one month ago had about 26 degrees max spark advance. I upped that to 36 degrees max, though we found that by backing it off from 36 degrees to 34 degrees over 4400 RPM yielded about 10 HP and some torque.
Favorite AF ratio is about 12.7, the car loses power higher or lower than that.
First are todays charts, I will then follow with the original charts preceeeded by some commentary.
Notice the across the board torque improvement and the smothing out of the 2000 RPM trough. There is something about either the headers or manifold (or both) that was causing the car to run way lean between 1800 and 2300 RPM. That was partially corrected by richening the fuel pulse duration in that RPM range.
It still appears to need some richening in the 2300-3000 RPM range, based on my interpretation of the graphs.
The baseline charts below show a couple almost identical runs that yielded about 300 HP, before all the tuning I did to the EFI, the two best runs were done with just an air cleaner base on the throttle body,and no airfilter, or the usual induction system I run, thus my comment about *as driven* above, i don't drive without an aircleaner.
Notice that even though the car yielded better HP and torque, the air fuel ratio was richer than I thought it would be compared to running with an induction system, as I was getting an air flow restiction of about 10% in the induction system, based on manifold vacuum, I would have thought letting more air in, would have leaned out the mixture instead of richened it.
next improvement is make the airflow restriction over 4200 RPM go away, which should get another 20-25 HP at top end.
I could never tune the car this well if it had a carb and mech distrib
Doug
The first chart shows the best run of today, with the best *as driven* run of one month ago.
In between, I recalibrated the timing and fuel,and today we tweaked the timing and fuel.
The original run of one month ago had about 26 degrees max spark advance. I upped that to 36 degrees max, though we found that by backing it off from 36 degrees to 34 degrees over 4400 RPM yielded about 10 HP and some torque.
Favorite AF ratio is about 12.7, the car loses power higher or lower than that.
First are todays charts, I will then follow with the original charts preceeeded by some commentary.
Notice the across the board torque improvement and the smothing out of the 2000 RPM trough. There is something about either the headers or manifold (or both) that was causing the car to run way lean between 1800 and 2300 RPM. That was partially corrected by richening the fuel pulse duration in that RPM range.
It still appears to need some richening in the 2300-3000 RPM range, based on my interpretation of the graphs.
The baseline charts below show a couple almost identical runs that yielded about 300 HP, before all the tuning I did to the EFI, the two best runs were done with just an air cleaner base on the throttle body,and no airfilter, or the usual induction system I run, thus my comment about *as driven* above, i don't drive without an aircleaner.
Notice that even though the car yielded better HP and torque, the air fuel ratio was richer than I thought it would be compared to running with an induction system, as I was getting an air flow restiction of about 10% in the induction system, based on manifold vacuum, I would have thought letting more air in, would have leaned out the mixture instead of richened it.
next improvement is make the airflow restriction over 4200 RPM go away, which should get another 20-25 HP at top end.
I could never tune the car this well if it had a carb and mech distrib
Doug
Last edited by AZDoug; 10-13-2006 at 11:29 AM.
10-12-2006, 07:59 PM
#2
Melting Slicks
nice going. So you are thinking to end up with 320-25 RWHP when all is said and done. those are some nice numbers and should make for a hell of a ride. How does the rest of the driveline feel when you jump on it. Is it hooking or spinning, does the car feel solid?
Thanks
Greg
Thanks
Greg
10-12-2006, 08:23 PM
#3
Race Director
Thread Starter
The car is very solid:
Narrowed 12 bolt diff with 3.31 gears, Richmond Gear 5 speed with 3.2x first gear, 2.20 second, and (from memory) about 1.6x third, about 1.2x fourth and 1:1 fifth. (last four gears are about same as M21)
Five and 1/2 leaf rear springs with Koni shocks and P265-50R-15 rear meats. The tires handle the power very well,and the extra half leaf on the spring sets keep spring wrap up from occuring.
It runs like a raped ape. First gear launches you, then bang second and you are gone. part throttle in any gear during cruise,and the car is gone.
I am going to take it to Firebird sometime soon and see how close to a 12:00 sec 1/4 mile I can get.
Only thing I would probably change since I am now running 24.5" tall tires rather than the 26.5" tires I had when i set up the rear end and tranny is go to a 2.73 or 3.08 gear set. Or figure out how to get a Richmond 6 speed OD tranny to fit....
Doug
Narrowed 12 bolt diff with 3.31 gears, Richmond Gear 5 speed with 3.2x first gear, 2.20 second, and (from memory) about 1.6x third, about 1.2x fourth and 1:1 fifth. (last four gears are about same as M21)
Five and 1/2 leaf rear springs with Koni shocks and P265-50R-15 rear meats. The tires handle the power very well,and the extra half leaf on the spring sets keep spring wrap up from occuring.
It runs like a raped ape. First gear launches you, then bang second and you are gone. part throttle in any gear during cruise,and the car is gone.
I am going to take it to Firebird sometime soon and see how close to a 12:00 sec 1/4 mile I can get.
Only thing I would probably change since I am now running 24.5" tall tires rather than the 26.5" tires I had when i set up the rear end and tranny is go to a 2.73 or 3.08 gear set. Or figure out how to get a Richmond 6 speed OD tranny to fit....
Doug
10-14-2006, 01:14 AM
#4
Melting Slicks
Give a shout when you head out there. I'd be curious to see how she runs with that gearing in a 327. To me, intuitively it would seem to be geared to short. But what the hell do i know. If it works, it works. I'd like to see it go.
10-14-2006, 01:49 AM
#5
Race Director
Thread Starter
Originally Posted by panchop
Give a shout when you head out there. I'd be curious to see how she runs with that gearing in a 327. To me, intuitively it would seem to be geared to short. But what the hell do i know. If it works, it works. I'd like to see it go.
Not too short at all. Firts gear doesn't need to be 3.3, probably 3.1 would be better, but that is what it has
probably go there November 3 or whenever their Friday night open in November is is
Doug