low dyno numbers..
07-11-2015, 07:04 PM
#1
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low dyno numbers..
Just dynoed my new setup..and it's way lower than expected. 350whp/360wtq.
Engine specs..385 stroker,11.1-1 compression,le1 heads,le cam 227/235 .565/.579 111 +4, ported intake manifold,headers,52mm tb.
afr's looked good 12.8 at start of run,up to 13.2 at 6200. we started at 33 degrees timing and ended up with it at 38 degrees..with the computer adding more for a total of 43 at 6k...by looking at the data log.
So...do I need a bigger cam or something else going on... goal was 400+whp...now I'd be happy with 380
Engine specs..385 stroker,11.1-1 compression,le1 heads,le cam 227/235 .565/.579 111 +4, ported intake manifold,headers,52mm tb.
afr's looked good 12.8 at start of run,up to 13.2 at 6200. we started at 33 degrees timing and ended up with it at 38 degrees..with the computer adding more for a total of 43 at 6k...by looking at the data log.
So...do I need a bigger cam or something else going on... goal was 400+whp...now I'd be happy with 380
07-12-2015, 05:20 AM
#2
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Re: low dyno numbers..
Heads are a little small for a stroker! I would have went with at least le2 or le3's. And a 58mm throttle body. Do you have long tube headers and what size injectors are you running? Overall though I think the heads are restricting you!
07-12-2015, 10:03 AM
#3
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Re: low dyno numbers..
yes long tubes...running 30lbs right now...they where starting to max out...but still was a 13.2. Data log didn't show much of a restriction with a 52mm tb.
Hard to believe these heads are restricting me that much.... my stock motor/stock heads went 314/339 with a cc503 cam.
Hard to believe these heads are restricting me that much.... my stock motor/stock heads went 314/339 with a cc503 cam.
07-12-2015, 12:21 PM
#4
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Re: low dyno numbers..
Lloyd's website indicates the LE1's can make 400+ rwHP, but with his 232/240 .578/.574 110 LSA custom cam. So you're marginal on the cam. Maybe the LE2's would have been a better choice.
30#/HR injectors would exceed 90% duty cycle at 400rwHP (460 flywheelHP through the M6) unless you have a very efficient tune. You're marginal on the injectors. Did you measure the HP while trying slightly richer A/F ratios?
I feel the 52mm TB should be OK.... engine dyno testing on my engine indicated that a 58mm TB was oversize at 496 flywheel HP. Could have made it on a 52mm.
30#/HR injectors would exceed 90% duty cycle at 400rwHP (460 flywheelHP through the M6) unless you have a very efficient tune. You're marginal on the injectors. Did you measure the HP while trying slightly richer A/F ratios?
I feel the 52mm TB should be OK.... engine dyno testing on my engine indicated that a 58mm TB was oversize at 496 flywheel HP. Could have made it on a 52mm.
07-12-2015, 01:06 PM
#5
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Re: low dyno numbers..
Lloyd's website indicates the LE1's can make 400+ rwHP, but with his 232/240 .578/.574 110 LSA custom cam. So you're marginal on the cam. Maybe the LE2's would have been a better choice.
30#/HR injectors would exceed 90% duty cycle at 400rwHP (460 flywheelHP through the M6) unless you have a very efficient tune. You're marginal on the injectors. Did you measure the HP while trying slightly richer A/F ratios?
I feel the 52mm TB should be OK.... engine dyno testing on my engine indicated that a 58mm TB was oversize at 496 flywheel HP. Could have made it on a 52mm.
30#/HR injectors would exceed 90% duty cycle at 400rwHP (460 flywheelHP through the M6) unless you have a very efficient tune. You're marginal on the injectors. Did you measure the HP while trying slightly richer A/F ratios?
I feel the 52mm TB should be OK.... engine dyno testing on my engine indicated that a 58mm TB was oversize at 496 flywheel HP. Could have made it on a 52mm.
On a side note..did pacesetter have a earlier design header? Mine has a plate with 2239 on them...looking at them on summits site..they look different than mine. Mine is crimped at the flange at the head....stepped down...
07-13-2015, 08:47 AM
#7
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07-13-2015, 09:12 AM
#8
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Re: low dyno numbers..
The conservative formulas for sizing injectors recommend that you not exceed 80% duty cycle, to prevent the injectors from going static, or simply flowing less than they are rated for, with a poor spray pattern. My less conservative rule-of-thumb is 85% max. If you assume that limit, assume a brake specific fuel consumption (BSFC) of 0.476 #/HR/HR, you come up with a handy formula for normally aspirated applications that says multiply FLYWHEEL HP X 0.07 to get the minimum recommended injector size.
With your goal of 400 rear wheel HP (~460 flywheel HP), that would result in a recommended 32.2 #/HR injector. Why not just go to 36 #/HR and allow sufficient fuel for days when you can make more than the dyno chart HP due to dense air - high barometric pressure, low air temp, low humidity?
Not familiar with the Pacesetter variations. Are you saying that you have a "step" primary - the first couple inches is a larger diameter, then necks down to a smaller diameter?
With your goal of 400 rear wheel HP (~460 flywheel HP), that would result in a recommended 32.2 #/HR injector. Why not just go to 36 #/HR and allow sufficient fuel for days when you can make more than the dyno chart HP due to dense air - high barometric pressure, low air temp, low humidity?
Not familiar with the Pacesetter variations. Are you saying that you have a "step" primary - the first couple inches is a larger diameter, then necks down to a smaller diameter?
07-13-2015, 09:27 AM
#9
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Re: low dyno numbers..
The conservative formulas for sizing injectors recommend that you not exceed 80% duty cycle, to prevent the injectors from going static, or simply flowing less than they are rated for, with a poor spray pattern. My less conservative rule-of-thumb is 85% max. If you assume that limit, assume a brake specific fuel consumption (BSFC) of 0.476 #/HR/HR, you come up with a handy formula for normally aspirated applications that says multiply FLYWHEEL HP X 0.07 to get the minimum recommended injector size.
With your goal of 400 rear wheel HP (~460 flywheel HP), that would result in a recommended 32.2 #/HR injector. Why not just go to 36 #/HR and allow sufficient fuel for days when you can make more than the dyno chart HP due to dense air - high barometric pressure, low air temp, low humidity?
Not familiar with the Pacesetter variations. Are you saying that you have a "step" primary - the first couple inches is a larger diameter, then necks down to a smaller diameter?
With your goal of 400 rear wheel HP (~460 flywheel HP), that would result in a recommended 32.2 #/HR injector. Why not just go to 36 #/HR and allow sufficient fuel for days when you can make more than the dyno chart HP due to dense air - high barometric pressure, low air temp, low humidity?
Not familiar with the Pacesetter variations. Are you saying that you have a "step" primary - the first couple inches is a larger diameter, then necks down to a smaller diameter?
07-13-2015, 12:07 PM
#11
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Re: low dyno numbers..
assuming that he adjusted the tune for them...I am no tuner, but in tunercats there is an injector size prompt. I would not know anything after that in the fueling of the tune that needs to be changed (if anything)
07-13-2015, 12:50 PM
#12
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Re: low dyno numbers..
yes the tune was setup for the bigger injectors. Did a compression test on 3 of the cylinders... 199,199,205. I may try the others later..and a leak down test on my next off day.
07-13-2015, 01:53 PM
#13
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Re: low dyno numbers..
If it wouldn't idle with bigger injectors, then something is wrong. The injector size shouldn't have effected idle if the tune was right. The PCM would just call for a shorted pulse width and the same amount of fuel as the 30# injectors would be sprayed into the cylinders. I hope you find your issue, keep us posted.
07-13-2015, 04:52 PM
#14
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Re: low dyno numbers..
Obviously the PCM has to be tuned for any injector. Point is, as the injector size goes up, the pulse width at idle drops to the point where the PCM or the injector may not be fast enough to operate at that reduced pulse width.
I would wonder if someone tried to use a low impedance injector, when the LT1 PCM driver is only suitable for a high impedance injector. At least without an outboard adapter.
I would wonder if someone tried to use a low impedance injector, when the LT1 PCM driver is only suitable for a high impedance injector. At least without an outboard adapter.
07-13-2015, 05:29 PM
#15
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Re: low dyno numbers..
Obviously the PCM has to be tuned for any injector. Point is, as the injector size goes up, the pulse width at idle drops to the point where the PCM or the injector may not be fast enough to operate at that reduced pulse width.
I would wonder if someone tried to use a low impedance injector, when the LT1 PCM driver is only suitable for a high impedance injector. At least without an outboard adapter.
I would wonder if someone tried to use a low impedance injector, when the LT1 PCM driver is only suitable for a high impedance injector. At least without an outboard adapter.
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