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Dyno tuning



LONG, LONG, LONG!!

Finally decided that it was time to stop farting around and put the nephew's 
(Mike) car on a dyno and actually tune it.

Couple interesting things came out of this.
The first was that we wasted about 5 runs trying to fix the engine running 
lean at low RPM boost. We kept richening up the lean area at 3500 and below 
and kept seeing the 4500 RPM range richening up with no change at 3500. Well 
there's the length of the exhaust pipe and there's about 10 ft of tubing to 
the dyno's WB and that was essentially delaying the signal about 1000 RPM. 
5 wasted runs figuring out the dyno WB had a significant delay.

Once up into the higher RPM ranges the dyno WB was showing leaner running 
than Mike's Innovate LC-1 WB by about .5 AFR so we used that as calibration 
which was the point of using the dyno WB in the first place. So, basically 
we went back to Mike's original map that had a very consistent AFR from his 
tuning efforts, richened the whole boost portion of the map by .5 AFR and 
ditched the dyno WB. So, something to keep in mind and the most likely 
reason that dyno runs always seem to start off lean.

The second thing was that despite all the effing around with AFR in the 12.5 
to 13.5 range, we saw no significant difference in power. Richening it up 
did stop the engine from pinging when boost first came in though. 
http://i9.photobucket.com/albums/a95/jdbubb/86%20JH%20Turbo/scan0001.jpg 
That was about as far as we could go with fuel tuning. I figured we were 
about done cause when we started we had some pinging.

Mike's using a Cheapass (R) ball and spring boost controller that we cobbled 
up (works just as good as a Forge manual boost controller though!) and it 
allows boost to initially rise to 13psi, then brings it back to 10 psi and 
maintains that fairly well. That's why there's a big hump in the torque 
curve at 3800. That's also where we had some pinging.

So, the next thing to try was spark advance. Again, at 3800 and 13 psi we 
were already, apparently, on the limit. So we progressively added more 
advance at higher RPM. 1 degree at 4200, 2 at 4800-6200 and 3 at 7000. We 
did this several times and the progression can be seen here: 
http://i9.photobucket.com/albums/a95/jdbubb/86%20JH%20Turbo/scan0003.jpg
Advance at 3600 and below was unchanged, but the engine definitely liked 
more advance at higher RPM and we were able to bring the high RPM torque up. 
Advance at 6200 went from 17 to 23 degrees by the time we started pinging 
again.

Lastly we tried increasing boost. We had essentially been tuning at 160 kpa. 
Increasing boost only 1.5 psi brought fairly significant pinging (BTW, you 
should hear pinging on the dyno. It's almost like the engine's sneezing, but 
it's a really hard mechanical sneeze ;^) so we started bringing the advance 
in the 190 kpa range down to compensate. In the end we ended up with 
virtually the same power we had at 10 psi boost since we had to pull so much 
advance out. So, that was that. Back to 10 psi boost and call it a day.

Also of interest is watching an engine on the dyno. They move around a LOT!! 
Towards the end of the day we could almost tell how well the run had gone 
just by watching the engine position. No top end, you could see it relaxing 
in the mounts! Last run, it was leaned back all through the run. ;^)
First and last run comparison: 
http://i9.photobucket.com/albums/a95/jdbubb/86%20JH%20Turbo/scan.jpg

Eighteen runs, $200, we'd learned a few things, got a shitload of data and 
picked up 13 peak hp with an even bigger difference above 5400. 186whp @ 
5400 on 10 psi boost and 220 lb-ft @ 3800. Maybe not huge numbers but this 
is an incredibly streetable turbo. Where before it was all about using the 
midrange and shifting early, now it's still pulling strong at 6500. ;^)
Imagine Mike sneaking up on sooo many unsuspecting suckers driving this: 
http://i9.photobucket.com/albums/a95/jdbubb/86%20JH%20Turbo/100_0759.jpg 
What a kick in the butt to drive!!

What's next? Mike's engine apparently isn't very detonation resistant. Gotta 
get around that and run some more boost.

One of these days I'll have more power than my nephew! :^(

Dan