ZX-Tex

iTrader: (15)

No, not for certain. No higher than 16 psi, so somewhere between 15-16.

Stephanie Turner

You can run above 14:1 as long as your ignition timing is controlled. 12.8:1 at the top end is perfectly acceptable as long as there is no engine knock. BTW - the 12.8:1 was done on the dyno. When I street tuned it, it was running 12:1. So there is no way you can blame it on being too lean.
Stephanie

paul

iTrader: (21)

Then I got 2 factory freak motors because my other 99 motor was making 300 with this setup. I grenaded the oil pump though because of the underdrive pulley/missing AC bolt through oil pump/bouncing off rev limiter.

Tim also makes 290 on a stock engine and as Artie already stated he makes 275. Those are stock 94/95 bottom ends.

I tune for 12.1 afr

patsmx5

iTrader: (16)

Does ANYBODY have the timing map he was running? If yall tuned it, do yall have a copy? I've asked this multiple times, even asked Matt himself and everybody ignores the question... I suspect he was running too lean for the timing yall were running on that motor. IE-had he ran richer, say 12:1 or 11.5:1, it would not have began to detonate and bend the rods. (assuming it detonated, which I would assume it did...)

patsmx5

iTrader: (16)

Yeah, I wonder.... I still these people bending rods are running too lean and getting a touch of detonation that's bending the rods. Just my opinion, but it's better to run 11.5:1 AFR at 13.8 PSI vs. 12.8:1 AFR at 13 PSI and make the same hp.

y8s

iTrader: (8)

it amazes me that people think they can hear detonation while driving around...

patsmx5

iTrader: (16)

Exactly. I'm no expert on all this, but it can detonate and you not hear it, but normal combustion is not happening and peak cylinder pressures are going up up up. It can lead to knock. That's my understanding. And Matt's car bent rods on a 6th gear pull to redline. That's when it would happen if it was gonna happen.

y8s

iTrader: (8)

the wind noise alone at 140 mph would make it virtually impossible to hear anything. the exception might be if you had a set of det cans, then maybe. but i doubt you'd be wearing them at that point.

Savington

iTrader: (31)

blinky light on my dashboard hears it for me.

*blink blink* "HEY ******** YOU'RE SCREWING UP, I SUGGEST YOU STOP"

Stephanie Turner

From what Matt told me the afternoon it all went down, even Matt is not sure when it happened. It happened while driving on the highway at 90-100 mph. The noise from the bent rods was not audible until the were getting off the highway. So there was a 150 mile stretch where something happened, Bryce drove the car, acceleration and cruise happened, but I don't think they know for sure when it was.
Stephanie

Stephanie Turner

Yes, I have the map. Matt does not have a copy. He was not running too lean. If knock occurred, I really feel like it was an isolated incident. Maybe it overheated and the person driving it did nto notice? I can't say for sure though.

I have driven and tuned the car enough to ensure it was running good AFR's under boost. Granted, no all knock is audible, especially with his exhaust! But I have never heard the engine ping.

My laptop is at home, so I would have to look at the most recent map later tonight. I will let you know how much ignition retard it had.
Stephanie

patsmx5

iTrader: (16)

When I said too lean, I meant "too lean for a street driven car, in my opinion". I'm sure it makes more power running 12.8:1 AFR than it would at a richer mixture, assuming no changes to timing were made.

I don't know how his timing map was tuned. IE-did the tuner find the minimum best torque timing value and keep that , or did they take 1* or 2* out of that value as to give it a safety margin? Only the person who tuned the spark table knows. Running it at 12.8:1 AFR's doesn't give much of a safety cushion as far as AFR's go.

Anyways, I'm interested to see the timing map he was running.

ZX-Tex

iTrader: (15)

Yes I have one of those too. Plus I have an electronic 'det can' setup that I can use whenever I am driving around/tuning. All I have to do is turn on the stereo and select aux in. The knock is audible much sooner this way than just listening normally. Plus if road/wind noise get too loud, I just turn up the stereo.

In fact that is why my map is backed off from the timingz thread examples. I heard some very light knocking with my det can setup and backed off the timing by a few degrees on most of the map. The knocking was not audible otherwise.

Stephanie Turner

Tim does all the dyno tuning. He tunes for fuel curve, then starts adding in timing. He usually leaves a 1.5 degree threshold of knock. Depending on how street tuning goes, I usually do not make many changes to the timing table. But then again, it was back in March of '08, so it does not surprise me that I do not remember. If I do not write something down, I will forget about it.

When the car comes to me for street tuning, the AFR is usually much richer than when it was on the dyno. I always find that if it did 12.5:1 on the dyno it is at 11.5:1 on the street. I usually leave it unless it goes below 10:7 or above 12.5:1. As I cannot remember what his AFR was on the street, I do not remember if I made changes or not. But I do make it standard to leave all cars below 12.0:1. When the engine gets broken in, and I go to tune it again, we will see what the first dyno pull reads.
Stephanie

hustler

iTrader: (6)

I'm one of the "11.5:1 AFR at 7psi+" guys...but I see 4k-7k rpm for 30-minutes at a time.


Also, since I track this car a few times per year in OK...I wonder if I should tune on 91 octane since that's all I can get up there...aside from "purple" at the track.

Savington

iTrader: (31)

So which wideband is inaccurate?

hustler

iTrader: (6)

...and everyone makes fun of my "det-cans." I'm not making a thread about blowing my **** up either. hmmm...


The det-cans were nice because when I was road tuning I could hear the roar get stronger and stronger, then sometimes here very faint "tink...tin....................tink............... ....tink.tink." I couldn't hear that when doing pulls right next to the concrete barricade.

Stephanie Turner

It is not that one is in accurate, I think it has to do with run conditions, etc.. The car is running at higher temps on the dyno vs. the street.

For example, we usually see a 1 psi difference between the dyno and street, when relying on a gauge read out. If it is dyno that reads boost pressure during the run, that is a different story and they are usually the same. Our dyno does not do that, we rely on gauge info. I am not smart enough to tell you why, so my best guess is due to engine load and the fact that the car is strapped down.
Stephanie

y8s

iTrader: (8)

the tune should accommodate changes in ambient atmospheric conditions via air temp sensors and coolant temp sensors.

Savington

iTrader: (31)

I can tune my car at 2am in 35 degree weather and it runs 10.9-11.1 during 4th and 5th gear pulls. I can then take that same tune and go pounding around CalSpeed in 80 degree weather, redlining 5th and 6th, and the wideband is pinned at 10.9-11.0.

I can see a difference in boost; my car makes a little more boost in 5th and 6th than it does in 3rd and 4th, and I can understand that more load means more boost. What I can't understand is why you see a one point discrepancy between the dyno and the street, and nobody else does.