Knock, knock....

[turbojimmy]

So I took my freshly rebuilt engine to the track today (neatly installed in my GN). It wasn't knocking on the highway yesterday, but today I had 28" tall tires on it vs. my 26" street tires. I guess the engine has a bit more work to do.

I'm not sure how to address it. Here's what it's doing:

I'm running 93 octane and an OLD SMC alcohol kit with denatured. 21-22 PSI and 22.5 degrees of timing under boost at higher RPMs. WB02 is in the high-10s, low 11s. EGT shot up to 1700 just before the knock started.

I got 2 runs in today. On the first run, the knock gauge shot up into the red at about 75 MPH. I immediately let off and coasted to the finish line. On the second run, I turned the pump speed up to 7.5 (from 5.5) and this time the knock gauge went into the red at 85 MPH. I let up and finished at half-throttle.

So I'm thinking I need more alcohol, and probably a progressive kit? If I crank the knob on this old kit to 10, that's a helluva hit of alcohol when the boost first comes in.

Second, I noticed that my XFI config file had 25.75 degrees of timing at 3900 RPM at 22 PSI, but is 22.5 at higher RPMs. When it jumped from 22.5 degrees to the 25.75 degrees, that's when the knock started. What's interesting is that when I look at the log file, there is a huge drop in RPM (from 5300 to 3900) at 80 MPH. When it drops into this RPM range, the config calls for more timing. I didn't manually lock the converter until AFTER the knock event and after I had let off the throttle (at about 90 MPH).

So can I get away with bringing the timing down to 22.5 lower in the RPM range to compensate for the RPM drop at lockup, or do I need more alcohol, too?

Jim

 

[jasjamz]

That's a lot of timing for the 1st time out. 25* Try a max of 23* down low and 21* up top. Thats what my chip has in it. For pump and alky I would set the target A/F to 10.5. These seem to be the numbers you can start your tuning at without being so close to the danger zone. HTH

Oh and Get a kit from Razor and use meth....:biggrin:

 

[wickedtt]

So I took my freshly rebuilt engine to the track today (neatly installed in my GN). It wasn't knocking on the highway yesterday, but today I had 28" tall tires on it vs. my 26" street tires. I guess the engine has a bit more work to do.

I'm not sure how to address it. Here's what it's doing:

I'm running 93 octane and an OLD SMC alcohol kit with denatured. 21-22 PSI and 22.5 degrees of timing under boost at higher RPMs. WB02 is in the high-10s, low 11s. EGT shot up to 1700 just before the knock started.

I got 2 runs in today. On the first run, the knock gauge shot up into the red at about 75 MPH. I immediately let off and coasted to the finish line. On the second run, I turned the pump speed up to 7.5 (from 5.5) and this time the knock gauge went into the red at 85 MPH. I let up and finished at half-throttle.

So I'm thinking I need more alcohol, and probably a progressive kit? If I crank the knob on this old kit to 10, that's a helluva hit of alcohol when the boost first comes in.

Second, I noticed that my XFI config file had 25.75 degrees of timing at 3900 RPM at 22 PSI, but is 22.5 at higher RPMs. When it jumped from 22.5 degrees to the 25.75 degrees, that's when the knock started. What's interesting is that when I look at the log file, there is a huge drop in RPM (from 5300 to 3900) at 80 MPH. When it drops into this RPM range, the config calls for more timing. I didn't manually lock the converter until AFTER the knock event and after I had let off the throttle (at about 90 MPH).

So can I get away with bringing the timing down to 22.5 lower in the RPM range to compensate for the RPM drop at lockup, or do I need more alcohol, too?

Jim

Are you Locking the converter at that speed 75-85? What converter are you running?

 

[turbojimmy]

That's a lot of timing for the 1st time out. 25* Try a max of 23* down low and 21* up top. Thats what my chip has in it. For pump and alky I would set the target A/F to 10.5. These seem to be the numbers you can start your tuning at without being so close to the danger zone. HTH

Oh and Get a kit from Razor and use meth....:biggrin:

I didn't see the 25+ degrees at 3900 RPM in the config file until it started to knock. It's 22.5 degrees everywhere else above that RPM. I'm using XFI, which is not aware of what gear the car is in so I can't program it for 3rd gear timing. So, 25+ degrees is okay in 1st and second gear, but in 3rd gear with the converter locked it knocks. Not sure how to get around that other than trimming the timing back, but it will hurt in the lower gears. I will add some fuel - that might help, too.

Are you Locking the converter at that speed 75-85? What converter are you running?

I don't have FAST configured to lock the converter. I lock it manually, but I didn't lock it until AFTER I saw the knock. I had let compeltely off the throttle to stop the knock, gave it about half-throttle, and locked the converter. I was going about 90 according to the speedo. But the FAST log shows the RPM drop at 80 MPH, and before I lifted. It has to be the converter locking, but I don't know why. The MPH on the speedo and FAST don't line up completely, but it still shows the RPM drop before you can see the drop in TPS when I let off, which is not how it happened. I need to dig around in my config file to see if there's something other than "TCC Parameters" that might lock the converter.

Thanks,
Jim

 

[jasjamz]

I didn't see the 25+ degrees at 3900 RPM in the config file until it started to knock. It's 22.5 degrees everywhere else above that RPM. I'm using XFI, which is not aware of what gear the car is in so I can't program it for 3rd gear timing. So, 25+ degrees is okay in 1st and second gear, but in 3rd gear with the converter locked it knocks. Not sure how to get around that other than trimming the timing back, but it will hurt in the lower gears. I will add some fuel - that might help, too.



Thanks,
Jim

I would trim back the timing and see if the knock goes away. You should be able to make a complete run after that. Then, I would work on reaching my target boost level. When you get it there with no knock and you see the A/F is still in the safe zone, you could try to lean it out, or add timing to see if the car makes more power. Guys have made nice amounts of power without alot of timing. This is how I plan to tune mine this year. May take more runs to get reach your goal but being greedy and impatient cost me $$$.:redface: That XFI may just take some getting use to. Did you contact the vendon to see if he could review your log. You may want to post it here also because alot of guys may be able to assist you.

 

[turbojimmy]

I would trim back the timing and see if the knock goes away. You should be able to make a complete run after that. Then, I would work on reaching my target boost level. When you get it there with no knock and you see the A/F is still in the safe zone, you could try to lean it out, or add timing to see if the car makes more power. Guys have made nice amounts of power without alot of timing. This is how I plan to tune mine this year. May take more runs to get reach your goal but being greedy and impatient cost me $$$.:redface: That XFI may just take some getting use to. Did you contact the vendon to see if he could review your log. You may want to post it here also because alot of guys may be able to assist you.

I haven't contacted the vendor. I'll do that soon.

I was reading the manual for XFI. I can use the Power Adder feature to trim the timing and/or add fuel in 3rd gear or when the converter locks. It's not the intended function, but it will work. I just need to set up a relay to send 12V to the XFI module at the Power Adder Enable pin.

Thanks,
Jim

 

[jasjamz]

I didn't want to mention the manual thing but I figured it would help you. TurboT990 is good with that XFI! He reads that book during breakfast, lunch, and dinner lol! He is a super cool guy to deal with and you might want to fire a PM over to him and see if he can give you any pointers.

 

[wickedtt]

I didn't see the 25+ degrees at 3900 RPM in the config file until it started to knock. It's 22.5 degrees everywhere else above that RPM. I'm using XFI, which is not aware of what gear the car is in so I can't program it for 3rd gear timing. So, 25+ degrees is okay in 1st and second gear, but in 3rd gear with the converter locked it knocks. Not sure how to get around that other than trimming the timing back, but it will hurt in the lower gears. I will add some fuel - that might help, too.



I don't have FAST configured to lock the converter. I lock it manually, but I didn't lock it until AFTER I saw the knock. I had let compeltely off the throttle to stop the knock, gave it about half-throttle, and locked the converter. I was going about 90 according to the speedo. But the FAST log shows the RPM drop at 80 MPH, and before I lifted. It has to be the converter locking, but I don't know why. The MPH on the speedo and FAST don't line up completely, but it still shows the RPM drop before you can see the drop in TPS when I let off, which is not how it happened. I need to dig around in my config file to see if there's something other than "TCC Parameters" that might lock the converter.

Thanks,
Jim

Jim what torque converter are you using?

 

[turbojimmy]

Jim what torque converter are you using?

It's a 5-disk Vigilante.

Jim

 

[liv4gnz]

hey its bobby i met you at the track yesterday i had the 87 well the only other 87 there

didnt you still run like 11.9 or 11.4?

 

[turbojimmy]

hey its bobby i met you at the track yesterday i had the 87 well the only other 87 there

didnt you still run like 11.9 or 11.4?

Yes, it ran an 11.4. I let up half-track because of the knock. I think that would've been a 10-second pass.

Jim