What do ya'll think? (A/F were 12:1 on the top end)

Not to shabby for a 4# lower huh?

BTW: Can ya'll help me figure out what the bobble on the top end is? I had a new Fuel filter in and it was getting richer the whole time so I don't think it's fuel. Has a new proper sized gatorback belt... Could it be a little slip?

Rich (mods on my web page)

 

Great numbers!

I put mine on the dyno at last years NMRA and had the same "bobble" on the top end. I showed the dyno sheet to Sal and he said that usually (but now always) indicates the engine is starving for air. What kind of filter are you running?

 

12" conical on a REM elbo. Has'nt been cleaned since the middle of last year. It's not really dirty either. Hum... I cleaned the IC only about 300 miles ago too. Since it's only a 4# lower I don't think it would be running out of air?

Rich

 

I forgot to mention that at the time of my dyno I was running a 4# lower with the stock airbox with a hole in the bottom, so in my case it probably was starving. Don't sound like that is the problem in your case though.

 

That's an interesting "bobble". I don't know what RPM's are at the far right of your graph, but the HP curve looks pretty flat there for a bit - and unless thats some kind of "anomelie" of the dyno itself - that "bobble" effect at the ends could represent; "valve float" and/or "erratic camshaft(s) actions" or "erratic ignition" and maybe all at the same time. I don't what all went into the design of the "camshaft/chains/chain idler tension" assemblys for our engines, and how "closely" they are/are not manufactured and assembled to spec's, but I know that generally, crank to camshaft timing chain's, when they start exceeding around 5000 rpm's, tend to resemble a passle of rattlesnakes stepped on by a herd of buffalo.

 

where did they start the pull from?? Can you post a pic so we can see the rpms????

That squiggle could be directly related to the tune. How bout an a/f line??? A 4lb lower shouldn't make you run out of fuel unless you had a pump issue. A buddy of mine dynod and and a/f shot right up at the end of the run. The problem was thought to be the pump relay.......something about the second pump

 

The pulls were in 3rd with the convertor locked. Started at 3300 and went to 5500.

A bone stock 02 was on the dyno right after me and his was a little jumpy towards the end. More like little spikes -vs- mine being more of a flowing up/down curve. Which btw coinsides with the fattest part of the A/F line. (dipped below 12:1 right there)

I'm not too worried about it. Just thought it might stick out to someone whos seen it before.

Rich

 

mine was done on the same Dyno and I don' thave a bobble, however, Rich added a few things so a reburn will clean up that bobble.

also... R,
my Dyno graph was done from Idle up to 5500...
the Shift RPM was set at 5450