-
(safe) timing #'s with different fuels by SH4DY on 21 Feb, 2017 11:19
-
I'm planning on heading to the dyno this weekend to dial in the car and was just curious what kind of timing people are running on their boosted LS motors.
Historically, I've only tuned these motors on pump gas and low (<10psi) boost (street cars) and kept timing pretty conservative in the 10-12* range to keep things safe. Plugs generally look pretty good and the motors last.
This trip to the dyno is with my personal drag car (stock piston/rod LS1) and I'm running VP110 and planning on running 15-ish psi. MS3pro with no knock inputs so there will definitely be some apprehension.
I figured I would start with my "street" timing curve and get the boost sorted out, then creep up a degree or two - thinking 15-16* max.
Looking through maps I've seen anywhere from 10* to 18* north of 15psi depending on fuel type and/or meth injection.
Anybody want to chime in? -
#1 by freeskier7791 on 21 Feb, 2017 11:44
-
No experience with boosted cars but you can go 32* with race gas on NA. I think staying at 16* is safe and will still make plenty of power.
-
#2 by largeorangefont on 21 Feb, 2017 11:56
-
On 110 you'll likely be able to get more out of it than 15-16 degrees, but there are too many variables to really get a meaningful answer. The process you stated is the best way to go.
-
#3 by coltboostin on 24 Feb, 2017 23:04
-
Bone stock Ls1, down to the cam!
This was on 23-24 psi. Cam2 110 out of a pump down the street. 17 deg up top. Took 2 seasons and a few accidentally 30psi pulls to bend a rod. -
#4 by SH4DY on 01 Mar, 2017 19:07
-
What plugs were you running? I had BR7ef's in there gapped at .028" and it was not happy under a lot of load. Thinking they are too cold. 2nd gear pulls at 6 psi were fine but when in 3rd (th400) it would hesitate so badly i would have to abort the pull- wouldnt go past 3,800. Afrs were 11.5, 14# of timing, 6# of boost and holding . I picked up some TR6's that im going to gap down to .025" to see if that helps. Wonder if I'm fighting the 110 octane fuel?
EDIT: I'm also going to try increasing the dwell to 3.5ms and see what that does (up from 3 - LS2 coils). -
#5 by SH4DY on 01 Mar, 2017 21:47
-
#6 by blacksi on 01 Mar, 2017 21:54
-
I ran 15 degrees once boost came on for years, then tried to bump it up more for the GA 1/2 mile to 17 and melted number 7... That was on 93 and around 9:1 compression. I usually shot for 11.8 AFR but errored to the low vs the high.
-
#7 by coltboostin on 02 Mar, 2017 10:43
-
What plugs were you running? I had BR7ef's in there gapped at .028" and it was not happy under a lot of load. Thinking they are too cold. 2nd gear pulls at 6 psi were fine but when in 3rd (th400) it would hesitate so badly i would have to abort the pull- wouldnt go past 3,800. Afrs were 11.5, 14# of timing, 6# of boost and holding . I picked up some TR6's that im going to gap down to .025" to see if that helps. Wonder if I'm fighting the 110 octane fuel?
I was on 7's. Same set of plugs for a whole season
EDIT: I'm also going to try increasing the dwell to 3.5ms and see what that does (up from 3 - LS2 coils).
Yes on baby boost stick with a 6. I would not go 7's unless you are consistently above 14psi. Gap .22-24I ran 15 degrees once boost came on for years, then tried to bump it up more for the GA 1/2 mile to 17 and melted number 7... That was on 93 and around 9:1 compression. I usually shot for 11.8 AFR but errored to the low vs the high.
On a 1/2 mile pull with 15psi Im shocked you were dicking around with pump gas. Everythings gets so damn hot on a pull like that-you want the coolest cylinder possible. I am 100% sure you would have been fine on better gas. -
#8 by coltboostin on 05 Mar, 2017 01:14
-
#9 by SH4DY on 05 Mar, 2017 18:04
-
No #'s... I didnt notch out the frame rails enough and the tires were swelling up and rubbing at higher speeds ( 275 MT ET street pro radials). I was able to work on the fuel tables some though so i may just forego another dyno session and just dial it in at the track. Just check the plugs and see what the mph does...
-
#10 by BlnLs1/rx7 on 08 Apr, 2017 19:54
-
No More than 18 degrees or your rolling the dice.