I'd be willing to guess that if you ran the TST or Hot Juice with the defueling based on EGT function turned off that they would continue to dump fuel into the engine. I have no solid proof to confirm or deny that, it's just my assumption.

 

Don't mean to change the topic, but it is somewhat rpm-related.
I have an automatic and floored it to merge into traffic coming back from a 100 mile trip. I saw it shift at 3000 or 3100, which surprised me. I did feel the power fall off just before it shifted. What concerned me is that I started smelling the oil I changed before leaving which I never did before. It's been raining so I couldn't really check to see where it might be coming from.
Not being broken-in yet, could blow-by have pushed some out somewhere?

 

From the dyno charts I've seen the TST doesn't do anything special up there. It defuels on EGT but that's 100% different than what the truck would normally do. The TST and I suspect the Juice, also, follow the stock power curve up there. They don't seem to do anything to try and defeat the defueling starting at 2750.

Andy

 

Hmm. I was under the impression that since they would defuel based on EGT that, if that feature was turned off, they would continue to put fuel in the engine past the factory 2750 defuel point. From looking at my dyno sheet from when the truck was fairly new, I don't see what I would perceive to be defueling beginning at 2750rpm. Now beginning at 2950, I can see a hard turn in the graph as the ECM starts to defuel.

Here is the graph of my truck that I was looking at to get my numbers. This was done on a Dynojet when the truck just had intake and exhuast. I've yet to dyno again with the BDDL, though.

For all intents and purposes you can disgregard the green line on the graph. That was a 6th gear pull just to see what affect it would have on overall power. I found it interesting that the toque number is way up under 2000rpm, but then it begins to match the 5th gear pulls that I made first.

Ok, enough of my armchair analysis.

 

I'm not sure I buy the 2750 rpm defueling thing, simply because peak hp is supposed to occur at 2900. How would they make peak hp at 2900 if defueling had started at 2750?

 

Hmmm interesting. Other dyno sheets I've seen show it starting around 2750...

Andy

 

Nope-I'm relying on what the engine is rated at by the manufacturer. I guess it could be wrong-it wouldn't be the first time that an engine made peak power at an rpm somewhat lower than the rating specified. I will say though that my truck does not feel like it defuels until about 3000 or so, however unscientific that may be.

 

I agree with v8440.

Let's start with how do you know that the defueling begins at 2750?

 

It must have been 2850, I can't remember anything anymore.

Andy