rgeier11

Buschur usually tunes cars with alcohol/meth. AMS is usually tuning with just pump gas for those numbers.

Also, more boost and less timing will always make more power, since detonation will occur with too much timing.

AMS

iTrader: (3)

A few things to answer your question. I made well over 500whp on our dynojet dyno 3-4 years ago on pump gas. Is it safe? no. Will it run for a while, yes. So no we haven't made any progress because we've already explored the limits a long long time ago and I won't let a customers car leave running on the ragged edge or even running in slight detonation.

Gary road races his car, It better to be running safe if it's getting flogged around the road course. A day at a road course is more abuse than a street car will see in a year!

Show me a dynojet sheet where Dave made 600whp on a dynojet. You're comparing his mustang dyno to a dynojet right? Well untill you actually put it on a dynojet you can't compare. I've had customers come from Dave's dyno and run on my dyno, the difference was less than 10%. I'm not putting Buschur down but saying that unless you compare #'s on the same dyno with the same correction factors, settings, ect, it's meaningless.

This is how it goes. To make more power you either have to run more boost or more timing. You're limited on the octane of the fuel so you can' t have both. You can make power easier and safer with more boost and less timing. It's a game you play where you find a point of diminishing returns at the knock threshold. I've pushed a car to 28psi and low timing. Trust me, it was detonating. You wouldn't know it unless you pulled the plugs and looked at them closely but it was detonating. For reference at 28-29psi , timing was about 1 degree at peak torque and 4-5 degrees at redline, even then it was on verge of detonation. Any more timing and it would trip the knock sensor harder and leave nice deposits of AL on the plugs.

It's really not that hard or magical to make more power on pump gas, it's just how risky do you want to be? I won't let a car leave my shop running on the edge of detonation because you never know when the conditions might change (fuel type, weather, ect) and push the engine over the edge.



Take a factory ECU, which is very good at detecting detonation. Try running big boost and low timing on pump gas, it won't let you. It will pull timing and do it before you even have a clue it's detonating. Now throw some 100 octane in there and see what happens, the timing comes back up. The AEM knock input just looks at raw knock sensor output and that's it, you can't distinguish the noise from valvetrain noise, knock, engine noise, ect. Factory knock algorithm is very complex and looks at knock events differently, usually it's very good ad isolating real knock events from engine noise. I rarely rely just on the AEM EMS knock sensor voltage, I always read plugs and use common sense.

In fact Chris and I are going to do a little test to show how you approach knock threshold and the signs to look out for.

-Martin

crcain

Wow great reply AMS.

I can't say I'm familiar with AEM knock control. I thought it had some sort of post processing from raw knock sensor voltage. And if I recall in a thread in Engine Management forum here, Dave has saying that it was critical to set up this post processing properly in the AEM. That said, I do recall Dave mentioning knock voltage as a raw number off hand recently, so I'm unsure what the scoop is on the AEM and knock.

I recognize what you are saying about safety margins. However, is there not active knock control on AEM? Are you suggesting you don't trust that active knock control?

I use Autronic which has no knock control and just use headphones (det cans) for mapping. Same thing with my tuner from England, just headphones. He puts out 600 crank horsepower regulary on 99 RON pump gas custmer cars. That is on an ECU with no knock control at all and he gets along pretty well in terms of customer car reliability.

Ultimately I think you can tune a 93 PON / 99 RON car to 2+ bar of boost safely. However, I respect what you are saying AMS because you guys obviously know what you are doing so I do take what your saying seriously. It sounds like your saying you prefer a larger margin of safety.

AMS

iTrader: (3)

knock processing is done in the AEM firmware you don't have control over. You do have control over what you do with that signal though (post processing). You can monitor knock raw or knock volts. Knock volts look at engine noise near ignition events but it doesn't which cylinder it happening on. Also if you're just monitoring Knock volts you have to do it at the highest sampling rate in internal EMS logging. Even then if the background noise is low and you can actually make a pattern out for knock events, you might not catch it because the sampling rate is just too slow. With knock control active, the EMS can actually catch knock events without you ever even seeing it on a high speed log.

I really do like a safety margin because I never know what the customer is going to do. Are they going to do a top speed run where they're running 29psi and low timing for 30 seconds at a time? I'm sure the exhaust valves, and pistons would not be too happy at this point, and then of course it's my fault. I've had some bad experiences so I have to be very careful. A good example is me getting sued because we made too much horsepower and the 18yr kept breaking his MR 6spd trans, even after we told him he would and should upgrade to a 5-spd. Fun times!

Ludikraut

iTrader: (17)

Keep in mind, though, that 99RON is only approximately equal to 93PON. From what I have read of RON tunes, it seems that 99RON is probably less prone to self-ignition than 93PON. Would be nice if we could test the two back to back sometime...

l8r)

crcain

Well said Martin.

Ludikraut I agree it's not a true apples to apples comparison.