8 cylinder front engine iconic vehicle
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By Crumpler
#71343
Hey guys.
Curious if anyone has messed around with the new generation of GPS technology for dyno testing?

I just got an RR Gtech unit. I have not done any actual pulls with it yet.
Conceptually I would enjoy having to not pay 100 dollars for three pulls at a shop while I attempt to tune the SC install.
It caught nine satellites when I plugged it in.
Set up includes weight, drive train loss, drag coefficient, frontal surface area. Pulls are initiated at 2000 rpm, recommended in second gear by manufacturers.
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By worf
#71347
How do the satellites measure a/f ratio?
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By Crumpler
#71358
Nope, just HP and torque.
But that’s that 928 dollar question, reliable data?
I’m not tech savvy, so it sounds like a virtual dyno to me.

Any AFR would be off my wideband. Any detonation would be off the knock sensor light.
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By N_Jay
#71363
I don't know why you need GPS, as I would think an accelerometer would be all you really need if the road is fairly level.
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By worf
#71401
Crumpler wrote: Mon Apr 05, 2021 12:12 pm Nope, just HP and torque.
But that’s that 928 dollar question, reliable data?
I’m not tech savvy, so it sounds like a virtual dyno to me.

Any AFR would be off my wideband. Any detonation would be off the knock sensor light.
What are you really trying to do?

If the purpose is to simply generate a 'bragging sheet' for the SC install then the 'virtual dynos' seem to do ok. There are various apps available that you can install on your phone.

If your purpose is to tune the SC install then... not so much really.

Let's back up and go at this bass akwards:

So...
- you have some mechanism and it generates a graph (or similar) related to SC system performance.
- what is it a graph of?
- if you don't like it what can you do about it?

Or in other words, what 'knobs' on the SC system can you 'turn' to tune it?

The answer to that question begins to tell you what you need for the 'mechanism.'

I assume you are not using a Shark Tuner?

So, if correct, the only knob you can turn is an adjustable fuel pressure regulator?
Last edited by worf on Mon Apr 05, 2021 7:39 pm, edited 1 time in total.
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By Crumpler
#71462
Fair observations.

The basic premise is if I paid for a dyno run at a pro shop would the graph look the same in basic intents and purpose as the graph on the gtech?

But walking it back, and all help appreciated, I need to establish gains with supercharger and boost levels.
So I guess I would be using it more as a quantitative tool then tuning with it, point taken.

The original goal was to add 100ish HP with low boost system with a stock ECU and FMU, and also not have to worry about detonation.

With the current pulley on the blower I seem to have three pounds of boost at wot. Not seeing more as rpm goes up, but I haven’t run it out all the way to rev limiter, etc.
No detonation seen and it was 80 degrees yesterday.
I’m also not seeing it lean out at WOT. So I can’t say any bad things yet.

My biggest issue yesterday was trying to do a controlled pull in Easter traffic on I-270 :(

Yes, no sharktuner yet. I would only have control over FMU and some MAF function. I have an 87 FPR, it’s not variable.
I could have, maybe, Ken make a chip to pull some timing a high end, but I’m not even there yet.
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By worf
#71542
Crumpler wrote: Mon Apr 05, 2021 4:49 pm The basic premise is if I paid for a dyno run at a pro shop would the graph look the same in basic intents and purpose as the graph on the gtech?
Usually an inertial dyno will log dyno speed and the shop will hook up an inductive sender to a plug wire and a tail pipe sniffer for rpm and a/f ratio logging. From dyno speed and rpm the dyno software will compute torque, horsepower versus rpm and also A/F at rpm. This is what's called "sweep tuning" and is mostly about not blowing shit up.

A/F at rpm is pretty much the minimum you need to do any useful tuning. However, what you see from a tail pipe sniffer in terms of accuracy is like horseshoes and hand grenades: You're seeing A/F at the tail pipe many many engine revolutions after it left the exhaust valve. So, about the only thing you can do is raise or lower A/F to try to find an optimum across the range with no lean spots.

OTOH, if you can do WOT runs on the road and not getting any knock then what you've got is probably safe. But, you've no way to determine if you're getting anything like the max possible power or if you're just dumping fuel out the tail pipe when cruising. For the former you have to log A/F from at least as close as a wide-band 02 sensor near the manifold. For the latter you have to do real tuning on a brake dyno.

Crumpler wrote: Mon Apr 05, 2021 4:49 pm I’m also not seeing it lean out at WOT. So I can’t say any bad things yet.
By what mechanism do you know that you're not lean?

And for WOT what consitutes lean?

Lean for WOT is not the same as lean for cruise.

Crumpler wrote: Mon Apr 05, 2021 4:49 pm My biggest issue yesterday was trying to do a controlled pull in Easter traffic on I-270 :(
Yup.

Crumpler wrote: Mon Apr 05, 2021 4:49 pm Yes, no sharktuner yet. I would only have control over FMU and some MAF function. I have an 87 FPR, it’s not variable.
I could have, maybe, Ken make a chip to pull some timing a high end, but I’m not even there yet.
You'd pull timing if you are getting knock with a known-good A/F ratio.

Are you using Ken's adaptive timing chips? Or are those EZK only?

For actually *tuning* you need to use a brake dyno that can hold the car at chosen specific loads and rpms. You'd choose these specific values to correspond with timing/load cells in the Shark Tuner and then dial in fuel and timing for each cell. Ideally you'd also log EGT so that you can see the effect of your tuning on EGTs.
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By Crumpler
#71577
Thanks Dave, appreciate your time on this one.

The AFR’s I’m getting at WOT are running low 12’s. The wide band is at the level of the O2 sensor on the other side of the xpipe. I equated that to ok but I don’t know if there is a different criteria forced induction to N/A?

The progressive chips are not available pre S4 as far as I know. If I take it further with a smaller pulley (ie get greedy) , I was going to reach out to Ken for some advice there about pulling timing at high end if I’m on razors edge with knocks.
This is a different thread but I’m looking for more boost sooner for the track. Coming out of corners into straights,etc. You know that would help me — instead of leaning how to drive better ;)
I’m usually not running super high rpms. :hitfan:

But, yeah I know this is all a lot of guess work without a shark tuner.
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By worf
#71683
Crumpler wrote: Mon Apr 05, 2021 10:23 pm The AFR’s I’m getting at WOT are running low 12’s. The wide band is at the level of the O2 sensor on the other side of the xpipe. I equated that to ok but I don’t know if there is a different criteria forced induction to N/A?
Good! I target A/F of 12.6. Lower is better than higher. If I see a 12.7 every once in a while ok. 12.8 then dial it down.

OTOH, if you're not seeing anything above say 12.1 or 12.2 you might gain a little power by leaning it out to get closer to 12.6 but it all depends upon the ability to make and resolve small FP changes.

All of the dyno runs of stock 928s I've witnessed run pig, pig rich above ~4500. I've seen low 10s...
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