What can I say, I'm a scientist - I needed numbers, and now I've got some. I'm going to make you read the entire post to see them, but that's just the kind of guy that I am.

I've needed to get some baseline data for some further tuning I think I need to do. Nothing wrong with the engine that I built, but it is hard to tinker without data (in fact I feel all dirty if I do that ). So I booked some time at the local dyno today. I've never run a car on a dyno before so it was a good learning experience, especially since the owner is one of the top local engine builders - so there was plenty of learning going on as I snooped around his shop (he's a Mopar guy - so obviously good people).

Here's what you see on the way in the door...

A high 9 second Camero (customer car)



A couple of Fury's (still love them):



A Olds that doesn't mind having the tires roasted.


My 122 was a little intimidated by all these muscle cars...



All strapped down and ready to go...on to the videos.

This was the pull to 6000 rpm...cam gave no signs of giving up...

[youtube]http://www.youtube.com/watch?v=_ahajtQaMz8[/youtube]

So we stepped it up to 6500 rpm.

[youtube]http://www.youtube.com/watch?v=eimDHKyvNHs[/youtube]

And the results are...Max power 133.2 Hp (wheels) @ 5980 rpm with 135.1 ft/lbs of torque @ 4450 rpm.

I'm pretty happy with that result (Wayne is sending me the data. AFR's are showing rich (with goofy stuff after 5000 RMP)) - so I'll have to find a leaner needle.



This image shows the torque and HP curves better. AFR's are flat and around 11.

Not too shaggy, Craig. Were you dinking with the ignition timing during all this? "Around 11" is pretty rich - you'll gain some power (not to mention life and economy) by leaning it up. It's not going to get you to 150 hp or anything, but it'll be good for another 5 ft-lbs maybe. Richening it up at the top end will definitely help peak power too, though it might not be a needle thing, based on how jerky that graph is. I'm wondering if you're getting some sort of intake or exhaust harmonics that's screwing things up around those speeds? Could be in the carbs: pulsation from it hitting a resonant pitch, popping the piston up and down, or maybe the exhaust just got to a resonant frequency that starts sucking fresh air back up the tailpipe.

Ya, the Dyno opperator was thinking that it was fresh air being drawn into the pipe...my bung was in a place that he couldn't get his wide band installed in the downpipe. He figured if it really was that lean in the upper end we'd see that on the HP curve - and it isn't there. So I've got to weld in another bung (try 3). The graph is not smoothed (in fact when you zoom in you can see the events very clearly). He usually smooths them using a 5 cell filter - I had him turn that off so I could see the data (it is on by default).

We played with the timing a little, but decided to leave it alone as the AFR's need to be fixed first - my sense was to change one thing at a time. He figured there was 10 - 15 hp left on the table with it being too fat and timing.

I was really impressed with the torque curve's flatness - you can see the blip I've noticed in the power band - it looks like a rich blip at around 2300 rpm. So I've got to find a leaner needle with a little leaner in the upper needle standard.

Damn, makes you want to play on one of these things all the time.

That "rich blip" is just tip-in, isn't it? A little lighter oil would cure this, but I wouldn't bother since when you put in a thicker needle you'll probably appreciate the slight richness.

I'm not sure about the 10-15 hp thing, but he's the operator. If you average out the funkyness above 5000 and assume it's going slightly lean, I'm thinking you might gain some, plus by leaning out the rest you'll gain some torque, but it won't be earth shattering. I imagine you stand to find more in the timing, but you never know how close you are.

The leaning might help your run-on too, you never know!

Sure does sound nice on camera, though.

I dont' know if it is tip in or not? I was thinking the right plan of attack would be to source some leaner needles (I have another set of the BBB's but nothing for the HIF's that are leaner) - couple of sets. Then play with the various combinations on the dyno. It's not megasquirt - but there you go...oil, sandpaper and a drill press...Dr Pushrod's tuning kit.