Cam "chop" gone after e85 upgrade - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

Oxtar41 · 02-24-2023, 10:09 AM

So I bought this car in December and the first video is how the car sounded on 93 and meth Injection. You can hear it was really choppy, the second video is how the car sounds after the second owner installed a fore tripple pump system, 1700cc injectors and e85 tune. Would the choppyness being gone be due to the tune? I noticed this car is super fat on the bottom end. Idles around 11.4 afr. I'm having it retuned in may by a shop I trust. It makes around 850-900rwhp I'm told on 18psi with twins. What do you guys think?

https://imgur.com/a/8kdUia0

https://imgur.com/a/5Gaz9qX

bsn · 02-24-2023, 10:48 AM

Yes the tune can affect the chop, If your running E85 you need to read Lamda not AFR.

Oxtar41 · 02-24-2023, 10:53 AM

Quote:

Originally Posted by bsn

Yes the tune can affect the chop, If your running E85 you need to read Lamda not AFR.

I was just reading off the afr gauge in the car

gtstorey · 02-24-2023, 12:26 PM

Does it actually have a larger cam? Or was the original a "ghost" cam in the tune?

dreksnot · 02-24-2023, 12:58 PM

The E85 modifier table (called Flex Fuel Spark) most likely added/removed idle timing and the result ended with a smoother idle, if that's the route the E85 upgraded was incorporated into the tune (the right way). If they just modified the main spark tables, there is a slight difference in how the difference fuels likes spark (how much). Easy to change in tune to get it where you want.

Oxtar41 · 02-24-2023, 01:52 PM

Quote:

Originally Posted by gtstorey

Does it actually have a larger cam? Or was the original a "ghost" cam in the tune?

It does infact have a big cam in it, the motor is fully forged and built.

Oxtar41 · 02-24-2023, 01:53 PM

Quote:

Originally Posted by dreksnot

The E85 modifier table (called Flex Fuel Spark) most likely added/removed idle timing and the result ended with a smoother idle, if that's the route the E85 upgraded was incorporated into the tune (the right way). If they just modified the main spark tables, there is a slight difference in how the difference fuels likes spark (how much). Easy to change in tune to get it where you want.

Good to know!

bsn · 02-24-2023, 04:03 PM

If you are running E85 you don't want a 14.7-1 ratio. E85 is 9.8-1 your gauge should have a setting for lambda . If you go by AFR you have to know what mix of gas and alcohol you have-you would have to recalculate every time you fill up. Lambda will always give you an accurate reading no mater what the mix. An added bonus its much simpler to understand. The ideal target is 1 lower than 1 is rich higher than 1 is lean. I have a feeling the tune you have now is probably spot on.

https://ftyracing.com/tech/lambda-afr-table/

02-24-2023, 10:09 AM	#1
Oxtar41 Drives: 700 rwhp 2010 SS Join Date: Sep 2010 Location: Garage.. Posts: 803	Cam "chop" gone after e85 upgrade So I bought this car in December and the first video is how the car sounded on 93 and meth Injection. You can hear it was really choppy, the second video is how the car sounds after the second owner installed a fore tripple pump system, 1700cc injectors and e85 tune. Would the choppyness being gone be due to the tune? I noticed this car is super fat on the bottom end. Idles around 11.4 afr. I'm having it retuned in may by a shop I trust. It makes around 850-900rwhp I'm told on 18psi with twins. What do you guys think? https://imgur.com/a/8kdUia0 https://imgur.com/a/5Gaz9qX __________________

02-24-2023, 12:58 PM	#5
dreksnot Served USN - Atomic Chimp Drives: 2021 Camaro ZL1 1LE A10 (stock) Join Date: Jul 2012 Location: Fort Collins, CO Posts: 1,642 View My Garage	The E85 modifier table (called Flex Fuel Spark) most likely added/removed idle timing and the result ended with a smoother idle, if that's the route the E85 upgraded was incorporated into the tune (the right way). If they just modified the main spark tables, there is a slight difference in how the difference fuels likes spark (how much). Easy to change in tune to get it where you want. __________________ > > 2021 Camaro ZL1 1LE A10* - power upgrades in the initial design phase* > > Past Builds: 2013 Twin-Turbo LSX434 M6 - 1,359rwhp daily

02-24-2023, 10:48 AM	#2
bsn Drives: 2013 ZL1 Join Date: Sep 2021 Location: Virginia Posts: 367	Yes the tune can affect the chop, If your running E85 you need to read Lamda not AFR.

02-24-2023, 12:26 PM	#4
gtstorey Drives: 2010 Camaro SS2,L99, LSA SC Join Date: Aug 2017 Location: Huntsville, AL Posts: 2,280	Does it actually have a larger cam? Or was the original a "ghost" cam in the tune?

02-24-2023, 04:03 PM	#8
bsn Drives: 2013 ZL1 Join Date: Sep 2021 Location: Virginia Posts: 367	If you are running E85 you don't want a 14.7-1 ratio. E85 is 9.8-1 your gauge should have a setting for lambda . If you go by AFR you have to know what mix of gas and alcohol you have-you would have to recalculate every time you fill up. Lambda will always give you an accurate reading no mater what the mix. An added bonus its much simpler to understand. The ideal target is 1 lower than 1 is rich higher than 1 is lean. I have a feeling the tune you have now is probably spot on. https://ftyracing.com/tech/lambda-afr-table/