Did the dyno killed my engine

[docrodg]

*sniff* I love a happy ending!

[175K911]

Originally Posted by JeremyD

Well the good news is that it was running strong - right before it died. 210 at the wheels is a solid number for a carrera. 250 on the bottom end is a number that 98% of the population would be happy with. ......

I agree, those are pretty healthy numbers for a stock motor. My '86 with European Racing headers, M&K 911 muffler and custom software just eeked out 202 WHP. Granted it's got 193K miles on it, and I ran it on a Dyno Dynamics dyno which are known to be pretty realistic in their numbers rather than some of the other brands out there that offer "marketing HP numbers" or "CA HP" as one well respected engine builder once told me.

[carnutzzz]

Did you really spin the motor "back and forth"?

[Louie85]

Thanks again to all. Time to start saving for a future rebuild.

"Did you really spin the motor "back and forth"
Yep, I did 1/2 revolution counter clockwise and 1 full revolution clockwise with no plugs. I was worried about spinning it backwards because from what I've learn here that the chain could jump out.

[84_Carrera]

213whp here, '84 3.2L stock / original top & bottom, just about to crest 100k here. M&K, Fabspeed Premuffler, Weltmeister chip (Blech!), +6% fuel setting on the DME, cone filter.

[Louie85]

Dyno results. 3 pulls and the last one is to figure out the drivetrain lost to calculate the crank horsepower.

[911st]

If I am reading this correctly you are running mear 14/1 AFR's.

That is to lean and might also be costing you HP.

Glad your back in shape.

[Louie85]

911st, yeah that's what the dyno operator told me too. Is this something I can adjust or do I need a custom SW chip.

[dtw]

Just want to reinforce that you're not out of the woods. If there is significant up/down play in your distributor shaft, you have a time bomb. The distro gear will eventually get spit out the side of the case by the crank, and then you are really SOL. You need to inspect your distributor immediately. If it was just a loose or unseated rotor, great - but you don't usually run into those on a running engine.

[Louie85]

Thanks DTW, I havent driven the car yet just fired it up I'm still in investigation mode. I'll pull the distributor and check end play and also check out the distributor gear. Also can you give an advice on the AFR reading on the dyno sheet, I thought when your on full throttle the AFR goes rich but the dyno chart looks like its leaning out.

[jurhip]

Just to prevent future rumors, a dyno is no harder on your engine than a full load run in a higher gear on the street. The only realy difference (for your motor), is a slight reduction in hot air exhaust efficiency. For the short time a car is on a dyno, that shouldn't matter too much.

[Steve W]

Great dyno numbers, but on the AFRs, either something on your engine is causing it to run lean, or the AFR sensor of the dyno is in error. I say the probably of either is equal.

If your car, make sure:
a) your pin 10 California/Japan wires are disconnected
b) your fuel quality switch in the DME is in full counterclockwise position
c) fuel pressure is correct at 2.5 bar with the vacuum line disconnected from fuel pressure regulator and you do not have an aftermarket FPR
d) no intake air leaks, especially from the intake manifold gaskets
e) other possibility is wear on the AFM, which decreases output voltage leaning out the mixture. May not be likely on your car because of how linear the AFR curve is. FRWilk has a page on checking and renewing the AFM here:
http://www.the944.com/afm.htm

The other possiblity is the dyno's sensor is off. Dynojet's use a remote vacuum pump and a long hose and probe to suck an exhaust sample, and needs frequent maintainence of the gaskets and seals to prevent sucking in false outside air which will cause a lean reading. If they don't do this enough, the only way to get an accurate reading is to put the wideband O2 in the O2 bung in the exhaust, or use the Innovate Motorsports tailpipe adapter. The wideband O2 sensor also needs to be periodically recalibrated with the drive circuit to maintain accuracy as the sensor goes through use.

You can always have the chip custom remapped to the correct optimum AFR ratio, but you don't want to use it as a bandaid to fix an outside issue if it exists.

[Louie85]

Steve thanks for your input and the check list. I'll go through the list and with my LM-1 this weekend.

[dw1]

More on AFM cal. for a 3.2:

http://forums.pelicanparts.com/porsche-911-technical-forum/312961-3-2l-air-flow-meter-calibration-research-prodject.html#post2906385

and especially:

http://members.cox.net/widebody/AFM/AFM3.2LCalibration.doc

Glad to hear the engine is mostly ok. Especially since I also have a 3.2 with SW chip, euro premuffler & dansk sport exhaust (but '87 & lower mileage than yours).