363 YSI (PICS)

[flyin_hawaiin]

what kind of fuel are you running on those passes? C16?

[BOSS LX363]

what kind of fuel are you running on those passes? C16?

Ya. Those are with 22 degrees total timing, with 16-17 lbs of boost. Both are leaving at 800 rpm. Both runs are around a 9.36-9.40 at 148-149mph.

[flyin_hawaiin]

Ya. Those are with 22 degrees total timing, with 16-17 lbs of boost. Both are leaving at 800 rpm. Both runs are around a 9.36-9.40 at 148-149mph.

the reason im asking about fuel is because when you see a "brown/rusty" colored exhaust gas come out of the exhaust with c16, that is detonation.... i know you said what the total timing is, but it may be lean OR too much timing at the initial launch... 99% of head gaskets blow at PEAK TORQUE, not peak hp.. peak torque is where the MOST cylinder pressure is... peak torque is also where the converter will flash too on initial launch.. im just giving you a heads up.. not trying to start any arguements..

[BOSS LX363]

the reason im asking about fuel is because when you see a "brown/rusty" colored exhaust gas come out of the exhaust with c16, that is detonation.... i know you said what the total timing is, but it may be lean OR too much timing at the initial launch... 99% of head gaskets blow at PEAK TORQUE, not peak hp.. peak torque is where the MOST cylinder pressure is... peak torque is also where the converter will flash too on initial launch.. im just giving you a heads up.. not trying to start any arguements..

Hmm, good to know. I heard some people say the opposite. They said since I run sunoco and their c16 is red, it could be unburned fuel? What do you think?

The initial stab would read around 10.6 on my wide band.

[flyin_hawaiin]

Hmm, good to know. I heard some people say the opposite. They said since I run sunoco and their c16 is red, it could be unburned fuel? What do you think?

The initial stab would read around 10.6 on my wide band.

ive run sunoco "maximal" fuel before.. it doesnt burn any specific color.. I have watched and tuned alot of cars like yours, and that is the first tell tale sign that it's detonated.. you see it ALOT on gear shifts too (not necessarily on your car, but on other cars).. most people dont understand that even if you are running a centrifical blower that increases boost with RPM, that your peak torque timing should still not be higher then peak torque.. if you look at a log, how much timing are you running out of the gate and how much when you shift (when it falls back to 5500-6000ish?).. if you are running more then your peak HP timing and your boost isnt falling off much, its too much... even if A/F was 8to1, it wouldnt matter.. on almost every STREET car i tune, i run more timing at peak HP then peak torque ...

PEAK TORQUE IS THE POINT WHERE THE CYLINDER PRESSURE IS THE GREATEST...

[BOSS LX363]

ive run sunoco "maximal" fuel before.. it doesnt burn any specific color.. I have watched and tuned alot of cars like yours, and that is the first tell tale sign that it's detonated.. you see it ALOT on gear shifts too (not necessarily on your car, but on other cars).. most people dont understand that even if you are running a centrifical blower that increases boost with RPM, that your peak torque timing should still not be higher then peak torque.. if you look at a log, how much timing are you running out of the gate and how much when you shift (when it falls back to 5500-6000ish?).. if you are running more then your peak HP timing and your boost isnt falling off much, its too much... even if A/F was 8to1, it wouldnt matter.. on almost every STREET car i tune, i run more timing at peak HP then peak torque ...

PEAK TORQUE IS THE POINT WHERE THE CYLINDER PRESSURE IS THE GREATEST...

That makes sense! On those runs I think the timing would be around 27 for a split second. On later passes I started to play with pulling timing on the launch. Man I need a lot of track time next year!

[flyin_hawaiin]

That makes sense! On those runs I think the timing would be around 27 for a split second. On later passes I started to play with pulling timing on the launch. Man I need a lot of track time next year!

when you blew the head gaskets, when did it happen? What RPM? What gear?

[BOSS LX363]

when you blew the head gaskets, when did it happen? What RPM? What gear?

It blew right before the 1/8 mile. I think the top of second at around 6800. But that was my first big boost pass. It went 5.91 in the 1/8 at only 109mph, so I think it happened right before. I should have threw it on the dyno before with the small pulley, but didn't. Next year I am done with the serp belts, only cogs from now on!

[flyin_hawaiin]

It blew right before the 1/8 mile. I think the top of second at around 6800. But that was my first big boost pass. It went 5.91 in the 1/8 at only 109mph, so I think it happened right before. I should have threw it on the dyno before with the small pulley, but didn't. Next year I am done with the serp belts, only cogs from now on!

you sure it wasnt when you clicked 3rd gear??

FYI.. 2nd gear makes CONSIDERABLY less HP then 3rd gear... if you dyno a car in 2nd then dyno a car in 3rd, there can be as much as a 100hp difference.. especially in a non lockup type transmission..

[BOSS LX363]

Not sure if this matters, but on that pass the converter got way looser.:D

[BOSS LX363]

you sure it wasnt when you clicked 3rd gear??

FYI.. 2nd gear makes CONSIDERABLY less HP then 3rd gear... if you dyno a car in 2nd then dyno a car in 3rd, there can be as much as a 100hp difference.. especially in a non lockup type transmission..

If it was, I just hit it.

[BOSS LX363]

Could it also be the cam? I only had 113ls, could that have trapped to much cylinder pressure with the larger boost?

[flyin_hawaiin]

Could it also be the cam? I only had 113ls, could that have trapped to much cylinder pressure with the larger boost?

no way its the cam.... i have run a ton of 112-114 LS cams... but, if you had just hit 3rd gear, THATS THE POINT THAT IM TALKING ABOUT... that is the hardest load that motor will ever see period..

[BOSS LX363]

no way its the cam.... i have run a ton of 112-114 LS cams... but, if you had just hit 3rd gear, THATS THE POINT THAT IM TALKING ABOUT... that is the hardest load that motor will ever see period..

On that pass the wide band never went leaner then 10.9. With less then 22 degrees of timing. It was the #6 cylinder and it ate part of the head. I think the fuel pump checked out and the wide band didn't have time to correct. Looking back, I had to have been just getting in to 3erd gear. Thanks Bob, the plan next year is to do a few minor changes and try to drop a half second.

[flyin_hawaiin]

On that pass the wide band never went leaner then 10.9. With less then 22 degrees of timing. It was the #6 cylinder and it ate part of the head. I think the fuel pump checked out and the wide band didn't have time to correct. Looking back, I had to have been just getting in to 3erd gear. Thanks Bob, the plan next year is to do a few minor changes and try to drop a half second.

99% of the time, detonation could care less about a/f.... if there is too much timing for a given cylinder pressure, running the motor at 8 to 1 a/f isnt going to help..

you said 22deg at peak HP, but look at your datalog.. i bet you had 25-27 when you pulled the shifter into third and the boost and RPM dropped.. you probably had 22 at the top of second (less load), but when you shifted, it went UP (and thats backwards thinking)..

anyhow, no prob on the insight.. good luck..