Joined
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807 Posts
It's done, the results are in, and it all makes sense....right? :-/
Run #1
http://speedtoys.com/~moon/1986/dyno/dyno09.gif
Run #4 (jumping over 2 tuning attempts)
http://speedtoys.com/~moon/1986/dyno/dyno12.gif
Pre-MAF run
http://speedtoys.com/~moon/1986/dyno/ldyno04.gif
It looks like there's room for improvement, as I'm running pretty rich, but clearly something wasn't right with the dyno, because according to the chart I briefly went back in time towards the end on both runs!
The first 2 tuning attempts I made were aborted each time it hit the lean spot ~4300rpm due to excessive lean, and I only got a little closer by my 4th run (he gave me an extra free run). What I'm trying to keep in mind, is that all my previous dyno sessions showed a 2 to 3 HP loss on successive runs, so factoring that into the gain achieved by the 4th run makes it easier to stomach. A gain of 3HP (5-6HP if you count the aforementioned loss) for a change in A/F of ~0.4 should point to a decent gain if I can get the a/f's closer to 12 and more linear. Surely another 6-7HP could be had. If those pieces can come together, I can get closer to the 10hp gain I expected from this deal (on a stock car mind you). How much can a better intake help if the exhaust is left restrictive?
So initially, I was disappointed with the numbers, but after having a few hours to mull it over, it seems to make sense to me. To inject a side note...my old Mk3 was there also and we gained 20hp by leaning a/f from ~9:1 to 10.5:1
...maybe a stock car wasn't the best guinea pig after all. BUT, my SOTP meter still tells me the car runs stronger, despite the numbers. I further question their accuracy, since my old Mk3 at 8psi ran a 14.6 1/4mile @98mph, but the dyno showed it only making 202hp, while in Vegas @ 12psi it put down 276hp.
Next paycheck I'll try a different dyno.
Run #1
http://speedtoys.com/~moon/1986/dyno/dyno09.gif
Run #4 (jumping over 2 tuning attempts)
http://speedtoys.com/~moon/1986/dyno/dyno12.gif
Pre-MAF run
http://speedtoys.com/~moon/1986/dyno/ldyno04.gif
It looks like there's room for improvement, as I'm running pretty rich, but clearly something wasn't right with the dyno, because according to the chart I briefly went back in time towards the end on both runs!
The first 2 tuning attempts I made were aborted each time it hit the lean spot ~4300rpm due to excessive lean, and I only got a little closer by my 4th run (he gave me an extra free run). What I'm trying to keep in mind, is that all my previous dyno sessions showed a 2 to 3 HP loss on successive runs, so factoring that into the gain achieved by the 4th run makes it easier to stomach. A gain of 3HP (5-6HP if you count the aforementioned loss) for a change in A/F of ~0.4 should point to a decent gain if I can get the a/f's closer to 12 and more linear. Surely another 6-7HP could be had. If those pieces can come together, I can get closer to the 10hp gain I expected from this deal (on a stock car mind you). How much can a better intake help if the exhaust is left restrictive?
So initially, I was disappointed with the numbers, but after having a few hours to mull it over, it seems to make sense to me. To inject a side note...my old Mk3 was there also and we gained 20hp by leaning a/f from ~9:1 to 10.5:1
...maybe a stock car wasn't the best guinea pig after all. BUT, my SOTP meter still tells me the car runs stronger, despite the numbers. I further question their accuracy, since my old Mk3 at 8psi ran a 14.6 1/4mile @98mph, but the dyno showed it only making 202hp, while in Vegas @ 12psi it put down 276hp.
Next paycheck I'll try a different dyno.