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This question is way over my head, but what the heck :)

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Old 03-19-08, 04:16 AM
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This question is way over my head, but what the heck :)

I'm probably over-reaching my boundaries, but I was looking at the S5 N/A Rtek 2.0 in the rtek forums. The +46HP at 6500rpm is VERY tempting. Problem is...I haven't the slightest clue about tuning or what is involved. I pm'ed ludwig and he says an "experienced tuner" can replicate the results in less than an hr. As a complete n00b, should I even bother?
Old 03-19-08, 04:39 AM
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+46hp just by swapping the ECU?
Uh, I doubt it.


-Ted
Old 03-19-08, 04:39 AM
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you'll need a dyno to check whether the changes you make are helping you or hurting. Plus, you can blow your motor if you horribly mess up the fuel map. I'd say without some background in it, leave it to a professional...the trouble is finding one that knows 7s.
Old 03-19-08, 04:57 AM
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Originally Posted by RETed
+46hp just by swapping the ECU?
Uh, I doubt it.


-Ted

The charts show most of the gain was on the high end. All they did was edit the fuel maps.
Old 03-19-08, 08:31 AM
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Here is the "before" graph from the digital tuning website



and here's the "after" graph



the main thing it accomplished, if you believe the dyno sheets, is expanding the usable rev range through fuel tuning.
Old 03-19-08, 10:57 AM
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I am no expert but that looks to me like a data error in the first graph- as the curves are identical but for one point or a few close points...

Could also have been a mechanical problem like a spark drop (bad coil?) fuel pressure loss (failing pump, cloggged filter) or something else causing the power to drop off significantly at that rpm which they fixed---

good luck but I would be skeptical if I were you.
Old 03-19-08, 01:57 PM
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The first dyno graph should not look like that, I would say something is wrong with the engine.

What are the S5 N/A's rated at? 165-ish HP? I'd hope they would put down more than 122 at the wheels stock...should be closer to 145-150.

Oh, and to answer your question, if you're ONLY doing it for fuel tuning, i'd just get an SAFC-II. Easier to use, harder to screw up, half (or less) the price...and if all you're doing is fuel tuning, expect the same gains. You can get a wideband and an SAFC and street tune it for free and get a decent tune on it.

46whp is probably a bit optimistic...I could easily see 10-15, maybe 20.
Old 03-19-08, 02:14 PM
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135.3 - 122.8 = 12.5
Did I do the math wrong?
So where did "+46" come from?
Even if you adjust for BHP, it can't be more than 15bhp...


-Ted
Old 03-19-08, 02:27 PM
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ted they are claiming that hp increase only at a specific rpm, not the peak power output.
Old 03-19-08, 02:31 PM
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Oh, you mean the big ******' dip in the first graph cause there was a hiccup or something was wrong with the car and then claim +46?
That's such a load of crap...


-Ted
Old 03-19-08, 02:34 PM
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lol

That dyno graph is soooo ridiculous.

Look at the curve! Apparently, an entirely stock S5 N/A engine makes a whopping 80 hp at 6000rpm. Bull-*******-****. Something is wrong with that, either the car had major issues, they lifted, the wheels spun or something. Because 6K is where an S5 N/A really starts to pull, it doesn't lose 50% of its power there.

The 2nd graph looks like a REAL stock S5 N/A pull.
Old 03-19-08, 02:56 PM
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The graphs are as real as the sun. I'm sorry if I've led anyone to believe every car could make an additional 46 peak hp but this particular car did. Was something wrong with it as baselined? Sure. What? Dunno. It simply wouldn't pull past 6000 rpm. The car in question was completely stock with the exception of an RB header. Still running the stock main cat, 6 port actuators confirmed to work, as well as the VDI actuator.

Why wouldn't it pull? Dunno. We weren't there to fix the car or to try to optimize the tune and see what we could make. We were there beta testing the Rtek 2.0 box and we were only there to confirm that we could accurately manipulate the fuel and timing. This car simply happened to be the guinea pig that volunteered. In the process of proving out the box we were able to go from the stock ECUs 11:1 - 10.7:1 a/f ratio at 6000 rpm + to a more power friendly 13.5 13.7:1. This change alone (timing was not altered between those two charts) allowed the engine to pull past 6000 rpm. Whatever caused the large dip with the stock ECU is still present in the Rtek ECU'd chart but it's been largely minimized. The vast majority of the power gain is in the engines ability to sustain revs and not in it's ability to make a ton more torque at any given RPM.

Again, my intention was never to mislead. The graph is pretty self explanatory. A better apples to apples comparison would be the charts I have posted on our website that compares an optimized stock ECU on an ITS racecar with the after results of tuning with the Rtek ECU.



Old 03-19-08, 08:22 PM
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Originally Posted by The Shaolin
The first dyno graph should not look like that, I would say something is wrong with the engine.

What are the S5 N/A's rated at? 165-ish HP? I'd hope they would put down more than 122 at the wheels stock...should be closer to 145-150.

Oh, and to answer your question, if you're ONLY doing it for fuel tuning, i'd just get an SAFC-II. Easier to use, harder to screw up, half (or less) the price...and if all you're doing is fuel tuning, expect the same gains. You can get a wideband and an SAFC and street tune it for free and get a decent tune on it.

46whp is probably a bit optimistic...I could easily see 10-15, maybe 20.
I managed to snag a S-AFC II in the forums for $180 =D. I guess it was meant to be! I'll pm you for more on how to tune this thing =).
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