toddk911

"I can tell you for a fact that Mustang dynos read low. Identical setups and no changes just the day. My car put down 246 whp on a dyno dynamics and 219 on a mustang dyno."

12% difference...Interesting.

toddk911

The only other reason for boost loss could be that they did not put the proper load on the rollers to your car would make full 12psi??

dand86951

Zero10 was at 177hp on the dyno not the 135 you have above, or did I miss something?

"I will get the charts up as soon as I can, but here's the end results.
177.4hp @ 5300RPM
199.1lb/ft @ 4400RPM"

sweanders

Yes, and also the fact that boost is not constant with a stock wastegate and turbo.

Zero10

Yup, that 135 number is at 3500RPM, which is what the other thread was about

I guess it could be the load on the wheels, but it seemed pretty close. They guestimated my car's weight at 3400lbs, which is slightly on the light side, and we did run in 3rd gear, but 6psi still seems low.
The run took ~10 seconds, which is about right to run from 3000RPM to 6000RPM in 3rd, so I think the weighting is pretty close to correct. I wanted to run in 4th gear, but the dyno operator didn't think that would be wise. I don't know the reasons behind it, but I put some faith in what he knows.

I'll be hunting vacuum/boost leaks soon, and chasing an oil leak as well.
I had a chance to run it hard on the street the other day, and even in 4th gear, I don't touch 10psi, maybe 8-9psi. I ran it hard in 3rd, but I was too busy watching traffic, and trying to wipe the stupid grin off my face (I have been driving a golf TDI for the last 4 months....)

If I had a cheap/affordable MBC or EBC I would replace the cycling valve, and that might help with the boost response as well.

SoloRacer

I weighed my car at the scales where I work and it came to 3200 lbs with a full tank of fuel so the 3400 lb guess would actually be fairly heavy - unless it is supposed to include driver.

danny951

if he is running 87 octane, his (stock) computer is pulling back timing and boost because of knock. that is my guess as to why he is only getting 6psi.

Zero10

danny951, that crossed my mind as well.
I did some more thinking, I see 8-9psi on the gauge, but mine is relative, his gauge is relative for sea level. That should read 2-3psi lower if my math works at all.

I am trying to rack up the miles on it, so that I can run the tank out, and re-fill with some 91 octane. If my boost goes up to an indicated 12psi (where it was before the winter), then we know exactly what happened.

Call me crazy, but I kind of want to put my chips and banjo bolt back in, mix about 50% xylene into the tank, and go make another pass

toddk911

"I wanted to run in 4th gear, but the dyno operator didn't think that would be wise. I don't know the reasons behind it, but I put some faith in what he knows."

Same when I did my recent run and also was on Mustang. Did the first run in 4th and was WAAYY low hp compared to 3rd gear.

They put weight from their list of all cars as 3250 for my run.

Danny: good point. For any dyno time you want to always run 93, if not higher just to be safe.

Zero10

I wanted to run 93, but my G/F was at the doctor's all day, and I was there with her. By the time we finally got out of there it was ~4 hours into the dyno evening (long story short, she has mono), and I was in a big hurry. Completely slipped my mind to top up with some 93/94 octane to try to bring the octane rating up.

Well, I finally got the dyno sheets scanned, sorry for the quality, but I'm no image expert.




I tried to properly overlay the big graph, since they could only print 2 headings at a time, but you can sort of see the back page through the front one...

I know my O2 sensor is shot, since it tells the engine that it is always running rich. Doesn't matter when making a power run, but it was interesting because at idle it showed between a 26:1 and 30:1 AFR. That seems a wee bit lean to me, I thought it would be around 17-19:1

toddk911

Idle usually arund 14.7. Mine dithers about .2 up and down from that.

That is one FLAT a/f curve. Wow!!

"idle it showed between a 26:1 and 30:1 AFR." I would say that is a false reading.

Zero10

I'm not sure that the AFR reading at idle is wrong, since it seems to be dead on when running. Between runs it would return to those readings.
Basically, upon starting the engine, the AFR would be 15:1 - 17:1, and for about 30 seconds thereafter (perhaps O2 sensor warm-up time?) it would stay in that range. Then it would gradually lean out to 20+:1.
When I lifted off the throttle after a run, it would go from 12.5:1 to 6:1 or so, then rapidly climb to 18:1ish, from there it's a slow climb to 25-26:1, and it would then wander up to 30:1, and back down.
It idles very poorly.

I saw the AFR curve, and was just shocked. Those are factory chips, and they sure seem to know what they were doing. The mixture is just about perfect, and man is that ever flat.
What's funny is how relatively flat the torque curve is. When I stomp on it the response is VERY non-linear, I expected to see a very steep curve on both sides of a ugly-positioned peak for the torque curve. It doesn't look anything like how it feels.

toddk911

I know when I first got my wideband I was suprised to see how the a/f jumps all around like you said. However, it should settle to 14.7. If your sitting at 18,20:1 that is some hot chamber temps.

Also, try a new O2 sensor. I went with a new one as most say about 3-5 years you should change and was sure mine was original 18 year old sensor

About 50$ from Pargon you can get the 3 wire which is a little more accurate then the stock 2 wire, not to mention a new one without years of carbon build up makes a difference.

I would love to see you do some runs and raise boost inbetween to see how the stock chips/DME etc. make adjustments.

I have said in the past that my mech said there is no need for all the aftermarket parts, MAFs, and "bells and whistles" as he says; that the stock system is perfect and he has had years of street and track experience with running NO wastgage and 30+ psi only regulated by how hard you were on the gas. Just bigger injectors and disable the boost cut and your on your way. He said the computer and other systems will adjust the fuel accordingly.

Of course you can imagine in here I was told "NO WAY!!!" but he has years of NON blown cars from street and track to prove it. FYI, this is a Porsche only shop, he is very good friends with Alex Job (Alex Job Racing) and really knows his ****.

toddk911

Although, if you did go back and play with boost to see if stock systems maintain that flat a/f and no knock etc., you might get a lot of tuners worried

sweanders

Your mech either suffer from very selective memory, compulsive lying or simply drives like a wuzz. There is no way to drive a car fast without being able to mash the throttle during acceleration.