MrClean

Ok; the peak numbers don't really tell the story...the peak hp only went up by 6 rwhp (torque increased by 22 rwftlbs), but the story is that in the meat of the powerband, between 3600 and 5500 rpm, the average increase was 22 rwhp (25 rwhp from 4300 to 5400). It seems that the original 93 Race tune was aggressive timing-wise, which led to early detonation (FYI, I only run Shell 93 Octane), so at 3600 the knock sensors would pull timing, creating a major dip in the power, from which the engine takes its time to recover (5600 rpm). The tuner removed timing, and leaned the mixture out a bit, which allowed the engine to not experience any detonation and therefore no pulled timing...which led to a much smoother hp and tq curve, and A WHOLE LOT of more usable hp and tq! See dynochart below......a picture is worth 1000 words...

DavidM

Thats a really good gain Marc! Good to know!

karman

Do you have the SAE chart?

wallace

oh!! let me tell you, even though i have a mail order, i will dyno first chance i get. buying a tune should require you to atleast buy a air/fuel monitoring device. LM-1, fast or something to report back to your tuner and necessary adjustment made if any, because as much as we trust our favorite tuner there should be no such thing as blind trust.

Fman67

Who's 93 octane tune are you using? How much timing did you take out and where? How much leaner?

tom281

Yep the area around the curve is very important...... congrats on the good numbers!

MrClean

Um, you mean the print out of the numbers of both runs at 100 rpm increments? Yes I do, but I didn't scan them...will do so L8r and post, if that's what you were referring to...

1. Bamachips 93 Race
2. I don't know how much,,,the tuner did it, but from the glimpse I cuaght it was a percentage thing, so it may have been accross the board...the bottom part of the chart shows the A/F...it went from ~12 (blue line) to just under 13 (red line) ..the red dotted line is 13.

Thanks! The cool thing is, it's actually a less aggressive tune!

MrClean

Here are the before and after shots...

karman

I think that explains a lot. A chart is worth 1000 words.
The before is SAE.
The after is STD.
If I run my numbers for my car at STD I get 292HP and 317 torque.
Of course, everyone uses SAE for comparison. Mine is 283HP 308 torque.
By running two different types of correction they have made it seem to gain more HP than it actually has.
I would guess you are actually @284HP.
In any case, to show increases you MUST go with the same correction factor before and after.
SAE is the more accepted correction factor.

65sohc

Was the AFR being being measured before the cats or at the tailpipe?

MrClean

Thanks for the education: now take another look at the chart (NOTE: the two sheets in the post immediately above are not charts, they're tables). If you had read my original post with more care you would have noticed that the peak mu,bers aren't that important to me; rather, the area under the chart is what is of the greater import (how much time do you spend at the peak hp?).

The area under the curve, even of the hp and tq curves are superimposed, is greatly improved because the milder timing setting keeps the PCM from pulling timing...again, EVEN IF THE PEAK NUMBERS ARE EXACTLY THE SAME.

But since you now peaked my curiosity, I'll get the SAE table for the "after" run and post it again. In fact, if you look at the factor next to the SAE and STD letters on both tables, I'll bet the SAE 1.0 stand for "no correction", while the the STD 1.02 stand for a correction of 2% higher, or "multiply by 1.02". So following that logic, 295/1.02=289....but I'll confirm.

MrClean

They unscrewed one of the O2 sensors, the most down stream one...looked like it came right out of the cat, and inserted the dyno's sensor there.

65sohc

You're right. An AFR in the 11's is pretty rich for a NA engine. I've got the same tune, albeit for 91 octane California swill. The approach would seem to be to dial in the AFR and then pull timing as necessary to avoid detonation. This makes more sense than running super-aggressive timing and then holding combustion chamber temps down with an overly-rich AFR. Now you've made me want to strap my car on to a dyno.

MrClean

65sohc: I agree, that seems to be what the tuner did. I've just spent some time tabulating and charting this data on excel, so I could "return" the after-dyno STD 1.02 to an SAE 1.0 (I'm assuming the "STD 1.02" does in fact mean the correction was a factor of 1.02)... and here are the results:

Peak HP: Before 282.51, & After 289.31
Peak Tq: Before 279.31, & After 301.33

BUT, the Deltas, from 3600 to 5500 RPM, average 18.21 hp, and 21.15 ftlbs, and the peak deltas are 20.75 hp @ 5000, and 23.59 ftlbs @ 3600.
Check out the excel file I attached, it has three tabs: the tabulated data, the SAE before and after dynocharts, and a chart of the hp & tq delta's....

Edit: FWIW, it doesn't bother me, whereas it seems to other people, that someone with similar mods gets more hp or tq....I'm just tickled pink at all the hp and tq under the curve that I'm recovering....all the way from 3600 to 5500 rpm...

karman

My mother told me never to assume...
They are two different types of correction based on temp.,humidity and barometric press. They have two different formulas based on two different atmospheric models.
Your STD correction factor was 1.02, your SAE was 1.00.
Those two numbers are meaningless for comparing on to the other.
More simply, STD typically will run about 4% higher.
That being said, you gained a couple HP and maybe 10HP+ in the powerband. Still an increase.
The real point is to compare you must run the same correction factor on both runs and that most people use SAE as the comparison to other cars. This can be done with the raw data on the Dynojet Winpep program.
Or if you get the oringinal uncorrected data, you can do it youself.

MrClean

Wow, pretty cool; I've saved the formula as a jpeg for future reference. I will no doubt be asking the tuner for the "after" SAE table, and a reprint of the chart with both dyno results in SAE form tomorrow....and will report back. In the mean time...4% huh?

I made a slight change in the spdsht to link the correction to one cell, therefore being able to play with it...here are the results with a correction factor of 1.04:

New HP: 283.75 (pretty close to your initial guess) and new TQ 295.54,
but more importantly, from 3600 to 5500, still an average increase of 13.36 hp (the highest delta was 15.36 hp at 5000), and an average increase of 15.56 ftlbs (the highest delta was 18.27 ftlbs at 3600). Revised spreadsheet attached.

MrClean

These are ALL Correction Factor SAE numbers, and all retreived from the WinPEP7 files (tabulated data exported to text, then Excel functions used to convert to numbers):
Before Dyno Max HP 282.59 / Max Tq 279.91
After Tweak Dyno Max HP 288.30 / Max Tq 301.51

The Delta's are as follows:


HP TQ
Min Increase 0.31 0.52
Max Increase 19.77 23.96
Average Increase 3200-6300 RPM 12.40 14.25
Average Increase 3600-5500 RPM 17.23 19.95

Here are the graph exported as a jpg file, and the tables exported as a txt file.

rick06gtmustang

So Dougs tune was a little rich,much better than being lean ib my book....I agree a dyno tune is a good thing if you can find one locally.

MrClean

That's a valid statement, of course, but the rich A/F didn't prevent the detonation due to the aggressive timing...

Hoops

wow this is very interesting reading...

MrClean, did you notice the knock snensors kicking in? Is that why you took your car to a custom dyno tune shop? I'm wondering if tripping the knock sensors is a common thing with bamachips?

Right now, today, my car is getting 4.10 gears installed at a Mustang shop that does dyno tuning. After talking to him about tuning options, my bill would be ~$900 for an SCT Tuner, C&L Racer intake, and a custom dyno tune for 87 and 93 octane.

Bamachips is $625 and tons of people have great things to say about those tunes.

Is it worth $275 to go with the custom dyno tune?