Peak torque move puzzling?

[randy331]

I'd throw all the dyno info from the session when the bearing was going bad in the trash. It's not good info.

If you look on the sheet when it was having bearing trouble, it wanted to make peak TQ at 5800 like it did after the bearing repair. It most likely freed the bearing up around 6300 for a bit and that let it make a bit more TQ for a few rpm. 491 @ 5800 493 @ 6300 with lower numbers in between.

Other dyno sheet looks more like a normal looking power curve.

I was in on a dyno session with a bearing going bad. Power was up and down. Make a pull with no changes and power was diferent.

Randy

[user-17438]

Water temps look much cooler on the dyno chart which made more power.
What fuel are you using?

Cheers

Judging by the bsfc.. diesel?

[John Wallace]

What's the far right column for?
(vacuum?)

[mag2555]

So your peak HP went up by 3% at 4 % less rpm, and your TQ went up 6% at 8% less rpm.
Friction from a bearing going away may be the cause for some of that , but like others have posted I would say the Cam went back in different , or the lash if used is now different!

It sure did take a lot less fuel once it was fixed to make peak TQ !

What caused the Bearing to go south in the first place?

[Frankshaft]

One thing is for sure, looking at the bsfc column, the thing should get really good gas mileage.

[n2xlr8n]

One thing is for sure, looking at the bsfc column, the thing should get really good gas mileage.

I thought that, too.

[gtca9014]

#236 peanut port combo?

241

[gtca9014]

One thing is for sure, looking at the bsfc column, the thing should get really good gas mileage.

I thought that, too.

I thought that too but plugs looked good and when fattened up power dropped off. Thought his gage was off but noticed in car, could get 4 runs before needing fuel in tank, use to be 3. Usually shoot for .42-.43 but have heard of mid .30s in high end stuff. It is what engine wanted.

[gtca9014]

So your peak HP went up by 3% at 4 % less rpm, and your TQ went up 6% at 8% less rpm.
Friction from a bearing going away may be the cause for some of that , but like others have posted I would say the Cam went back in different , or the lash if used is now different!

It sure did take a lot less fuel once it was fixed to make peak TQ !

What caused the Bearing to go south in the first place?

Not sure why bearing let go, was #4 main, all others good. How far off would cam need to be for 500rpm change? I wish it peaked @ 65-6700.

[gtca9014]

What's the far right column for?
(vacuum?)

Not sure, will ask

[gtca9014]

I'd throw all the dyno info from the session when the bearing was going bad in the trash. It's not good info.

If you look on the sheet when it was having bearing trouble, it wanted to make peak TQ at 5800 like it did after the bearing repair. It most likely freed the bearing up around 6300 for a bit and that let it make a bit more TQ for a few rpm. 491 @ 5800 493 @ 6300 with lower numbers in between.

Other dyno sheet looks more like a normal looking power curve.

I was in on a dyno session with a bearing going bad. Power was up and down. Make a pull with no changes and power was diferent.

Randy

I agree with your first sentence but in my other engine and a friends that are same combo, peak tq is in 6200-6400 range. If we can get it back up in this range it should be better.

[gtca9014]

I was hesitant to post the dyno sheets as it tends to get off topic quick here at times. Not slamming, appreciate all the replies but back to original question. What, in any application, would cause tq peak to move 500rpm? So far headers. Cam placement/lash but how much would it take?

[mag2555]

I believe a 500 rpm shift equals out to a 10 to 12 degree change in Cam duration.

[mag2555]

Wishing for a peak in the 6500 to 6700 range with out a HP goal to shoot for makes it hard for us to help you .

Also with out knowing what cid motor we are talking about here asking Peanut port heads to HP peak at 6700 rpm could take a wapping big Cam!

[gtca9014]

Wishing for a peak in the 6500 to 6700 range with out a HP goal to shoot for makes it hard for us to help you .

Also with out knowing what cid motor we are talking about here asking Peanut port heads to HP peak at 6700 rpm could take a wapping big Cam!

It is a low compression 9:1 402 BBC with oval port, not peanut port heads. Cam is 288/284 and mid .800 lift although cam guy wants to try higher lift on next one. Should be 700hp if good. My old one goes thru at 82-8400 with peak power at 7300. would like peak hp at 77-7800 and cross at 87-8800.