Is there a such a thing as cam surge in sd lt1’s
12-14-2020, 01:13 PM
#46
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Re: Is there a such a thing as cam surge in sd lt1’s
The other thing to try is to put in those voltage offsets I showed earlier. I remember when my offsets were incorrect, no amount of tuning could get the car to behave properly. When I got the correct ones finally, I could tell immediately on start up that it was right (it just felt and sounded spot on). After that, dialing in the tune was very easy.
Maybe it's a similar situation here?
Keep an eye on the WB O2 gauge though and don't nail the throttle right away... ensure your AFR's are good (not too lean) before laying into it.
Maybe it's a similar situation here?
Keep an eye on the WB O2 gauge though and don't nail the throttle right away... ensure your AFR's are good (not too lean) before laying into it.
my afr are no less than 11.8 and no more than 15.1
12-14-2020, 02:03 PM
#47
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Re: Is there a such a thing as cam surge in sd lt1’s
Like I said, they come from a different Bosch p/n, but seemingly from the same family of Bosch EV1 injector. So I'm hoping they're close enough, as was the case on the Bosch-III's I've dealt with in the past.
According to the bin you sent me, your tuners didn't touch that table... and are using the stock GM values, which are particular to the stock (Rochestor?) injectors. Generally when you change injectors, to be the most correct, you should get the factory offset values from the injector manufacturer. It could be that they're close enough or (as was the case in my experience) they could be way off.
According to the bin you sent me, your tuners didn't touch that table... and are using the stock GM values, which are particular to the stock (Rochestor?) injectors. Generally when you change injectors, to be the most correct, you should get the factory offset values from the injector manufacturer. It could be that they're close enough or (as was the case in my experience) they could be way off.
12-14-2020, 02:24 PM
#48
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Re: Is there a such a thing as cam surge in sd lt1’s
I punched those numbers in dec and all but when saved they rounded up. So is that ok?
12-14-2020, 02:26 PM
#49
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Re: Is there a such a thing as cam surge in sd lt1’s
That's fine. The values are in microseconds.
12-14-2020, 02:43 PM
#50
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Re: Is there a such a thing as cam surge in sd lt1’s
Ok good.
12-14-2020, 03:19 PM
#51
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Re: Is there a such a thing as cam surge in sd lt1’s
12-14-2020, 03:39 PM
#52
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Re: Is there a such a thing as cam surge in sd lt1’s
thing is. I burn my own chips. So not sure why he can’t help... I’m using tunerPro and make my own files as well. So not sure why he can’t make a file and send it to me?
12-14-2020, 04:19 PM
#53
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Re: Is there a such a thing as cam surge in sd lt1’s
We're getting off topic, but.....
Injectors are sized based on FLYWHEEL HP. With your 365 at the rear wheels, you are making 420-425 HP at the flywheel, through the T56. That's converted based on actual measured losses (chassis dyno vs. engine dyno) through my original T56 at HP levels ranging from 490 to 765 at the flywheel.
Put that 425 HP number in the overly conservative online injector sizing calculators (BSFC = 0.50 #/Hr/HP, 80% max duty cycle) and you get 33.2 #/HR. If the Bosch injectors you have are rated at the Ford typical 2.7 Bar (not all Bosch are rated at that pressure) they are only flowing 31.3 #/Hr at 3 Bar/43.5 PSI.
My guideline, which I've offered to people for many years is to multiply flywheel HP by 0.07 to get MINIMUM recommended injector size. That reflects a less conservative BSFC of 0.476 #/Hr/HP, and allows the duty cycle to reach 85%. 425 x 0.07 = 29.8 #/HR. Your at the ragged edge. What happens on a day the air is colder, the barometric pressure is higher, the humidity is lower than the dyno operator used to correct the dyno HP to SAE or STD conditions. You could run out of fuel.
There isn’t a lot of downside in going to a moderately “oversize” injector. You just have to be sure the program has the correct flow rates and offsets. Too big and the PCM drivers may not be able to turn the pulse width down low enough for a smooth idle. But the 94-97 PCM seems to be able to handle 42 #/Hr with no problems at idle. Don’t know about the 93. ECM.
Injectors are sized based on FLYWHEEL HP. With your 365 at the rear wheels, you are making 420-425 HP at the flywheel, through the T56. That's converted based on actual measured losses (chassis dyno vs. engine dyno) through my original T56 at HP levels ranging from 490 to 765 at the flywheel.
Put that 425 HP number in the overly conservative online injector sizing calculators (BSFC = 0.50 #/Hr/HP, 80% max duty cycle) and you get 33.2 #/HR. If the Bosch injectors you have are rated at the Ford typical 2.7 Bar (not all Bosch are rated at that pressure) they are only flowing 31.3 #/Hr at 3 Bar/43.5 PSI.
My guideline, which I've offered to people for many years is to multiply flywheel HP by 0.07 to get MINIMUM recommended injector size. That reflects a less conservative BSFC of 0.476 #/Hr/HP, and allows the duty cycle to reach 85%. 425 x 0.07 = 29.8 #/HR. Your at the ragged edge. What happens on a day the air is colder, the barometric pressure is higher, the humidity is lower than the dyno operator used to correct the dyno HP to SAE or STD conditions. You could run out of fuel.
There isn’t a lot of downside in going to a moderately “oversize” injector. You just have to be sure the program has the correct flow rates and offsets. Too big and the PCM drivers may not be able to turn the pulse width down low enough for a smooth idle. But the 94-97 PCM seems to be able to handle 42 #/Hr with no problems at idle. Don’t know about the 93. ECM.
12-14-2020, 05:46 PM
#54
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Re: Is there a such a thing as cam surge in sd lt1’s
We're getting off topic, but.....
Injectors are sized based on FLYWHEEL HP. With your 365 at the rear wheels, you are making 420-425 HP at the flywheel, through the T56. That's converted based on actual measured losses (chassis dyno vs. engine dyno) through my original T56 at HP levels ranging from 490 to 765 at the flywheel.
Put that 425 HP number in the overly conservative online injector sizing calculators (BSFC = 0.50 #/Hr/HP, 80% max duty cycle) and you get 33.2 #/HR. If the Bosch injectors you have are rated at the Ford typical 2.7 Bar (not all Bosch are rated at that pressure) they are only flowing 31.3 #/Hr at 3 Bar/43.5 PSI.
My guideline, which I've offered to people for many years is to multiply flywheel HP by 0.07 to get MINIMUM recommended injector size. That reflects a less conservative BSFC of 0.476 #/Hr/HP, and allows the duty cycle to reach 85%. 425 x 0.07 = 29.8 #/HR. Your at the ragged edge. What happens on a day the air is colder, the barometric pressure is higher, the humidity is lower than the dyno operator used to correct the dyno HP to SAE or STD conditions. You could run out of fuel.
There isn’t a lot of downside in going to a moderately “oversize” injector. You just have to be sure the program has the correct flow rates and offsets. Too big and the PCM drivers may not be able to turn the pulse width down low enough for a smooth idle. But the 94-97 PCM seems to be able to handle 42 #/Hr with no problems at idle. Don’t know about the 93. ECM.
Injectors are sized based on FLYWHEEL HP. With your 365 at the rear wheels, you are making 420-425 HP at the flywheel, through the T56. That's converted based on actual measured losses (chassis dyno vs. engine dyno) through my original T56 at HP levels ranging from 490 to 765 at the flywheel.
Put that 425 HP number in the overly conservative online injector sizing calculators (BSFC = 0.50 #/Hr/HP, 80% max duty cycle) and you get 33.2 #/HR. If the Bosch injectors you have are rated at the Ford typical 2.7 Bar (not all Bosch are rated at that pressure) they are only flowing 31.3 #/Hr at 3 Bar/43.5 PSI.
My guideline, which I've offered to people for many years is to multiply flywheel HP by 0.07 to get MINIMUM recommended injector size. That reflects a less conservative BSFC of 0.476 #/Hr/HP, and allows the duty cycle to reach 85%. 425 x 0.07 = 29.8 #/HR. Your at the ragged edge. What happens on a day the air is colder, the barometric pressure is higher, the humidity is lower than the dyno operator used to correct the dyno HP to SAE or STD conditions. You could run out of fuel.
There isn’t a lot of downside in going to a moderately “oversize” injector. You just have to be sure the program has the correct flow rates and offsets. Too big and the PCM drivers may not be able to turn the pulse width down low enough for a smooth idle. But the 94-97 PCM seems to be able to handle 42 #/Hr with no problems at idle. Don’t know about the 93. ECM.
12-14-2020, 06:35 PM
#55
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Re: Is there a such a thing as cam surge in sd lt1’s
Are you saying the injector offsets helped? that would be great news!
Though if you end buying new injectors, post up before you do. We need to ensure the ones you're getting have manufacturer data available for them. Otherwise you could end up in the same boat.
Though if you end buying new injectors, post up before you do. We need to ensure the ones you're getting have manufacturer data available for them. Otherwise you could end up in the same boat.
12-14-2020, 07:36 PM
#56
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Re: Is there a such a thing as cam surge in sd lt1’s
I’m keeping the 30lb for now. My mustang back in the day made more than this lt1 (302)sorry and had 30’s and drove perfect cam was a .666/.691 246/258 at 110. Turned that thing
To 7500 but let’s not get into that.
I just wanna learn all I can and tune so I can pass it on cause face it after us motor guys it getting slim.
12-14-2020, 07:45 PM
#57
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Re: Is there a such a thing as cam surge in sd lt1’s
I also think I screwed up the o2 swing. Thinking I needed to raise it but if o2 is saying it sees it to be lean so I should have lowered the swing to computer it’s ok to be lean????
12-14-2020, 08:35 PM
#58
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Re: Is there a such a thing as cam surge in sd lt1’s
I believe so. Basically you're telling it not to add so much extra fuel because "it's supposed to be that way" due to the cam overlap. You kinda have to try it both ways probably and see which one gets you the results you want.
12-15-2020, 11:52 AM
#59
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Re: Is there a such a thing as cam surge in sd lt1’s
so I put the offset and only change and it cleared up this surge but now I’m rich everywhere lol
12-15-2020, 11:57 AM
#60
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Re: Is there a such a thing as cam surge in sd lt1’s
Did you reset your VE tables back to stock?