Camaro XV

[mikels]

Originally Posted by Vince@MSperfab

Its common on RPM-MAP based ecus in race applications for the lowest MAP bins to be set at the max vacuum that you can pull while opening the throttle quickly. When you quickly close the throttle quickly at high-load, high-rpm, you can often get the MAP to dip below that value and it will cause a rich condition that produces popping and flames. You can tune it out by spreading out your MAP bins, but it will lower the resolution of your fuel tables in the normal operating range and hence isn't usually done in race applications.

Controller is GM E67 and is using MAF primary control with parallel speed-density control. So I have seen what you are speaking of, but this is slightly different.

Flames are result of how quickly ramp out of PE (power enrichment) combined with spark control when transitioning from on throttle to off throttle to DFCO (de-acceleration fuel cut-off).

Non-issue from an engine standpoint - from a visual, well, it barks flames on lift-throttle transitions from high airflow.

While there are many changes I can make that could reduce this effect, we haven't had time to revisit cal since last development trips to Gingerman and now OUSCI. That and some of those potential changes would be undesirable such as how quickly power drops when reducing accelerator pedal (@ 950hp, when you lift, you likely really want to reduce power.....)

Mark and I were talking that we've reached point where more power is not likely to result in much improvement of lap times (never thought I'd say that.....). Ability to maintain fluid temps at this power level has been a challenge as well - but Mark is now able to run 20 minute sessions in any ambient with controlled temps and no drop in delivered power.

First 7.0L supercharged engine (for road racing) we did at Thomson's in 2009 made 780hp/830tq. We are now at 950hp/970tq (1010hp/1020tq on E85). Amazing what refinements can bring paying attention to the details.

Dave

[ccracin]

Originally Posted by mikels

Controller is GM E67 and is using MAF primary control with parallel speed-density control. So I have seen what you are speaking of, but this is slightly different.

Flames are result of how quickly ramp out of PE (power enrichment) combined with spark control when transitioning from on throttle to off throttle to DFCO (de-acceleration fuel cut-off).

Non-issue from an engine standpoint - from a visual, well, it barks flames on lift-throttle transitions from high airflow.

While there are many changes I can make that could reduce this effect, we haven't had time to revisit cal since last development trips to Gingerman and now OUSCI. That and some of those potential changes would be undesirable such as how quickly power drops when reducing accelerator pedal (@ 950hp, when you lift, you likely really want to reduce power.....)

Mark and I were talking that we've reached point where more power is not likely to result in much improvement of lap times (never thought I'd say that.....). Ability to maintain fluid temps at this power level has been a challenge as well - but Mark is now able to run 20 minute sessions in any ambient with controlled temps and no drop in delivered power.

First 7.0L supercharged engine (for road racing) we did at Thomson's in 2009 made 780hp/830tq. We are now at 950hp/970tq (1010hp/1020tq on E85). Amazing what refinements can bring paying attention to the details.

Dave

The development you guys have put into this package is fantastic. Your work and attention to detail is very evident!

Your statement above is all the motivation needed to do an AWD 69! Hint Hint Nudge Nudge Wink Wink!

[LS7 Z/28]

Originally Posted by mikels

Mark and I were talking that we've reached point where more power is not likely to result in much improvement of lap times (never thought I'd say that.....

Mark Donohue would be proud!

[PTAddict]

Originally Posted by mikels

Controller is GM E67 and is using MAF primary control with parallel speed-density control. So I have seen what you are speaking of, but this is slightly different.

Flames are result of how quickly ramp out of PE (power enrichment) combined with spark control when transitioning from on throttle to off throttle to DFCO (de-acceleration fuel cut-off).

Non-issue from an engine standpoint - from a visual, well, it barks flames on lift-throttle transitions from high airflow.

While there are many changes I can make that could reduce this effect, we haven't had time to revisit cal since last development trips to Gingerman and now OUSCI. That and some of those potential changes would be undesirable such as how quickly power drops when reducing accelerator pedal (@ 950hp, when you lift, you likely really want to reduce power.....)

Mark and I were talking that we've reached point where more power is not likely to result in much improvement of lap times (never thought I'd say that.....). Ability to maintain fluid temps at this power level has been a challenge as well - but Mark is now able to run 20 minute sessions in any ambient with controlled temps and no drop in delivered power.

First 7.0L supercharged engine (for road racing) we did at Thomson's in 2009 made 780hp/830tq. We are now at 950hp/970tq (1010hp/1020tq on E85). Amazing what refinements can bring paying attention to the details.

Dave

It really is an amazing accomplishment making this kind of HP, pump gas, thermal management, and totally drivable. Crazy good. All on a production block and oiling system, as well.

Does the E67 ECU have any advantages over the E38 for this kind of application? Also interesting to note that you're running hybrid MAF/Speed Density - SD tuning on those ECUs is a PITA, at least with HP tuners, and I've found no discernable advantage in normally aspirated performance applications (the GM crate motor ECUs all run MAF-only as well). But it may well be that, at this HP level, that extra bit of fine transient control is important?

[GregWeld]

Originally Posted by PTAddict

It really is an amazing accomplishment making this kind of HP, pump gas, thermal management, and totally drivable. Crazy good. All on a production block and oiling system, as well.

Does the E67 ECU have any advantages over the E38 for this kind of application? Also interesting to note that you're running hybrid MAF/Speed Density - SD tuning on those ECUs is a PITA, at least with HP tuners, and I've found no discernable advantage in normally aspirated performance applications (the GM crate motor ECUs all run MAF-only as well). But it may well be that, at this HP level, that extra bit of fine transient control is important?

If you got to drive the car on the street.... you'd sell your house and buy a sleeping bag and move into the car if that's what it took to own it or one like it. LOL

Your Grandmother could drive this car home (to Pasadena) and be happy!

[66tintop]

Originally Posted by GregWeld

If you got to drive the car on the street.... you'd sell your house and buy a sleeping bag and move into the car if that's what it took to own it or one like it. LOL

Your Grandmother could drive this car home (to Pasadena) and be happy!

I have read that everyone says u suck ! But , I'm going to say , your one lucky bastard ! I'm sure all the rest of those other guys are drooling and tripping on their lower lip ! Me included !

[PTAddict]

Originally Posted by GregWeld

If you got to drive the car on the street.... you'd sell your house and buy a sleeping bag and move into the car if that's what it took to own it or one like it. LOL

Your Grandmother could drive this car home (to Pasadena) and be happy!

Well, I've been trying for a long time now to own one "like it". Problem is, Stielow keeps raising the damn bar But I'm having a ton of fun chasing that dream anyway.

[mikels]

Originally Posted by PTAddict

It really is an amazing accomplishment making this kind of HP, pump gas, thermal management, and totally drivable. Crazy good. All on a production block and oiling system, as well.

Does the E67 ECU have any advantages over the E38 for this kind of application? Also interesting to note that you're running hybrid MAF/Speed Density - SD tuning on those ECUs is a PITA, at least with HP tuners, and I've found no discernable advantage in normally aspirated performance applications (the GM crate motor ECUs all run MAF-only as well). But it may well be that, at this HP level, that extra bit of fine transient control is important?

E67 is needed for supercharged applications if wanting to maintain the same level of control as OEM. There are 3 MAP sensors (BARO, SC inlet and Manifold) as well as 2 IAT sensors (IAT1 in MAF sensor, IAT2 in manifold after intercoolers) and SC bypass valve control. E38 lacks the I/O capability to run this many sensors and have this level of control on forced induction applications.

MAF sensor allows more precise air measurement as well - when you think about it, speed density calibration is calculating the mass air flow from MAP, displacement and RPM to determine engine operation. Better to measure actual mass flow and redundantly calculate for better control.

Goal all along as we've refined these 7.0L SC engines has been not just power, but driveability, controllability and practicality (OEM part usage where possible for servicing, pump gas). Mark typically autocross's in 1st gear - not many 900+hp engines (well, none that I can think of) have driveability that allows this sort of operation.

We know there are changes that can be made to make more power, but what's the point if you give up the refinement and control? I think Charlie stated he got ~23-24 mpg in Mayhem on PowerTour this year (and I'm sure it wasn't because he 'babied' the car)- all while generating 880hp/815tq. On pump gas.

Anyone who can drive a stick could drive Hellfire - it is truly that easy to drive. Idles @ 750 rpm, pulls from any gear from idle speeds and never carries on in any way. Just be careful when your right foot gets heavy!

I'm a huge forced induction fan - and love turbocharging. But there is no way I can put together a turbo engine that has the same level of refinement and immediate response that we have with this positive displacement SC engine for same power level.

It's great fun making power (and can never have too much - although we are close.... Nah - just need more traction!) - but the fun stops if the package is unreliable, cantankerous to live with or requires unobtainium fuel, etc.

Dave

[Stielow]

Originally Posted by mikels

E67 is needed for supercharged applications if wanting to maintain the same level of control as OEM. There are 3 MAP sensors (BARO, SC inlet and Manifold) as well as 2 IAT sensors (IAT1 in MAF sensor, IAT2 in manifold after intercoolers) and SC bypass valve control. E38 lacks the I/O capability to run this many sensors and have this level of control on forced induction applications.

MAF sensor allows more precise air measurement as well - when you think about it, mass air calibration is calculating the mass air flow from MAP, displacement and RPM to determine engine operation. Better to measure actual mass flow and redundantly calculate for better control.

Goal all along as we've refined these 7.0L SC engines has been not just power, but driveability, controllability and practicality (OEM part usage where possible for servicing, pump gas). Mark typically autocross's in 1st gear - not many 900+hp engines (well, none that I can think of) have driveability that allows this sort of operation.

We know there are changes that can be made to make more power, but what's the point if you give up the refinement and control? I think Charlie stated he got ~23-24 mpg in Mayhem on PowerTour this year (and I'm sure it wasn't because he 'babied' the car)- all while generating 880hp/815tq. On pump gas.

Anyone who can drive a stick could drive Hellfire - it is truly that easy to drive. Idles @ 750 rpm, pulls from any gear from idle speeds and never carries on in any way. Just be careful when your right foot gets heavy!

I'm a huge forced induction fan - and love turbocharging. But there is no way I can put together a turbo engine that has the same level of refinement and immediate response that we have with this positive displacement SC engine for same power level.

It's great fun making power (and can never have too much - although we are close.... Nah - just need more traction!) - but the fun stops if the package is unreliable, cantankerous to live with or requires unobtainium fuel, etc.

Dave

Professor Mikels has spoken. I don't even mess with it any more I just do what Dave says and it works and hauls a$$....

[GregWeld]

Originally Posted by Stielow

Professor Mikels has spoken. I don't even mess with it any more I just do what Dave says and it works and hauls a$$....

Sadly I was unable to confirm.... LMAO