low compression 548 dyno testing has begun!!
#191
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From: frankenmuth michigan
Well, motor firing on all 8, new data aquisition showed up (not installed yet). 1st thing im seeing i do not like even with only 4 o2 sensors working is un-even afrs from cyl to cyl at different rpms, rons victor rpm also did this. We stagger jetted the carbs to help with it. We also thought perhaps once the flow was dry flow from tb that some of that would go away. No ability to tune cyl to cyl w mefi, if air flow is so uneven between long runners and short runners that afrs are 2 plus points apart at certain wot and part throttle settings would you really want too??. Again too, double firing the injectors on a mpi intake made the uneven afrs much better, doing it on this made it worse. As we move on i will be trying gimmefuels 105 mm tb on a 90 degree elbow, going to be interesting how IT affects un-even afrs. Not going to bother doing much more changes how ever till all the new data aquisition is up and running so we can capture afrs vs map vs rpms on all 10 02 sensors.
#192
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From: frankenmuth michigan
So now back to what everyone is really interested in, how does the 2200 cfm tb and efi compare to the carbs, right??
Well, results are NOT at all what I expected to see. There MIGHT be a tq or hp gain somewhere in the peaks with a little bit more tuning i am going to do as soon as the 2% correction factor air comes back (we were in the 4.5%range yesterday)
Anyways, 2200 cfm efi setup makes virtually same hp as norms magic 4150, what it DOESNT do is make torque. Tq peak shifted to 5400 from 4900/5000 and AFTER tayloring timing curve best tq was a dismal 608 ft lbs, we were in the 625/635 corrected range w the 4150. In the high 6 teens (616/618/620 ish ) with the dominators. Before changing timing in tq peak w efi we were making 597/599 peak. Now, does this GOOD carb magically make 22 more ft lbs but same hp, most likely NOT. I have always been under impression that a tb that flows too much wont really chsnge much at wot, the motor is basically "un-restricted" at that point, the ports/intake flow what they can flow but evidently that may be flawed. Next step is to try a couple more timing changes in tq peak and some slight fuel tuning but right now it looks like the high flow#s of the tb are hurting torque peak. Anyone have a 1200 or 1500 cfm 4 bbl tb i can borrow to test? Im about spent out on this project do really dont want to buy one to try!
Well, results are NOT at all what I expected to see. There MIGHT be a tq or hp gain somewhere in the peaks with a little bit more tuning i am going to do as soon as the 2% correction factor air comes back (we were in the 4.5%range yesterday)
Anyways, 2200 cfm efi setup makes virtually same hp as norms magic 4150, what it DOESNT do is make torque. Tq peak shifted to 5400 from 4900/5000 and AFTER tayloring timing curve best tq was a dismal 608 ft lbs, we were in the 625/635 corrected range w the 4150. In the high 6 teens (616/618/620 ish ) with the dominators. Before changing timing in tq peak w efi we were making 597/599 peak. Now, does this GOOD carb magically make 22 more ft lbs but same hp, most likely NOT. I have always been under impression that a tb that flows too much wont really chsnge much at wot, the motor is basically "un-restricted" at that point, the ports/intake flow what they can flow but evidently that may be flawed. Next step is to try a couple more timing changes in tq peak and some slight fuel tuning but right now it looks like the high flow#s of the tb are hurting torque peak. Anyone have a 1200 or 1500 cfm 4 bbl tb i can borrow to test? Im about spent out on this project do really dont want to buy one to try!
#194
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From: frankenmuth michigan
#196
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From: frankenmuth michigan
Theres more than their was and today its pouring rain, going to hold off on the final tweaking on this tb setup till we have those 2%cf days again, i dont trust the CF 100%, i feel its slightly flawed, when its damp, humid and warmer and cf goes from 2% to 4 or 5%, sometimes observed hp/tq drops 5% when it theoretically should have dropped 2 or 3% and have also seen the opposite. That's the main reason i tested all 4 carbs against each other in as short of time and w same air /cf to get accurate, comparitive data.
BUT, out of all of my testing these are bu far the lowest observed and corrected tq numbers and we have tested at 4.5% cf before
BUT, out of all of my testing these are bu far the lowest observed and corrected tq numbers and we have tested at 4.5% cf before
Last edited by articfriends; 03-25-2017 at 03:14 PM.
#197
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From: frankenmuth michigan
Whats going to be REAL interesting is how the cf on the depac with ITS weather station compares to the cf on the NEW dyno software with ITS auto correcting weather station! Like i mentioned, they will BOTH be up and running side by side!
#200
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From: Ontario, Canada
[QUOTE=articfriends;4540724]Well, motor firing on all 8, new data aquisition showed up (not installed yet). 1st thing im seeing i do not like even with only 4 o2 sensors working is un-even afrs from cyl to cyl at different rpms, rons victor rpm also did this. We stagger jetted the carbs to help with it. We also thought perhaps once the flow was dry flow from tb that some of that would go away. No ability to tune cyl to cyl w mefi, if air flow is so uneven between long runners and short runners that afrs are 2 plus points apart at certain wot and part throttle settings would you really want too??. Again too, double firing the injectors on a mpi intake made the uneven afrs much better, doing it on this made it worse. As we move on i will be trying gimmefuels 105 mm tb on a 90 degree elbow, going to be interesting how IT affects un-even afrs. Not going to bother doing much more changes how ever till all the new data aquisition is up and running so we can capture afrs vs map vs rpms on all 10 02 senso
Last edited by stimleck; 03-25-2017 at 08:57 PM.


