New pre-cup idea?

[JayTheCPA]

I took a walk through the Tech Library and read observations where it looked like a consensus of (presuming I got all of the details / assertions correct):
> need new head design to limit / control heat leach from the precup chamber to the coolant.
> probably need new piston design to allow longer valve durations for scavenging; turbo charging seems to compound the issue.
> maybe move the precup chamber to a central location relative to the cylinder.

Some of the material were long reads. :bigeyes2:

Solve the precup chamber's heat leach and system efficiency goes up.

Solve the scavenging issue and it allows for higher RPM's and probably better efficiency.

In terms of the precup design, did not get a strong impression that it had as much potential as the heat leach and / or scavenge issues. Trust me, I am on-board with the idea of getting more from the 6.5 as much as everybody else and the less invasive / costly the mod the better. Especially since another consensus was that the IDI principles that the 6.5 used were easily traceable to the early 1900's with not much in the way of notable R&D.

Naturally, am open to somebody correcting my interpretations.

 

[Burning oil]

Seems like a new head design is needed?

Wonder how hard and adaptor would be to make so a DMax head would bolt on :hihi: :joke:

 

[Will L.]

Yeah, the adapter would be the short block.

 

[RacinNdrummin]

^^^^^^^^ Ok so why do guys change out the small n/a precups for the larger turbo precups and pick up power?

Is there any solid back to back dyno proof on that around here?

I know there is a lot of talk, and a lot of people that say it added seat of the pants power, but a dyno is the only way your going to measure that, and its hard for somebody to dyno without making other changes....

 

[6.5L]

Dyno can also be manipulated. I personally don"t think precups play a huge role but I also think having a small precup is power robbing while having a precup doesn't perform well. I think a happy medium size would work best for power. Do you have any dyno number swapping between precups Racin??

 

[6.5L]

I meant too large precup. Dumb iPod

 

[schiker]

I don't remember any documented HP gains but seems there was mention of quantitative data on lower egt's and maybe even ect too.

 

[RacinNdrummin]

Dyno can also be manipulated. I personally don"t think precups play a huge role but I also think having a small precup is power robbing while having a precup doesn't perform well. I think a happy medium size would work best for power. Do you have any dyno number swapping between precups Racin??

No, the closest we have is the difference between my 7.3 Dyno, and NMB2's 6.9 dyno. NMB2 had stock 6.9 precups, which have smaller throats, and he put down 365whp@2800RPM on 130cc of fuel. That's pretty damn good for our IH's, and about a 2.8hp/cc ratio.

Im just not convinced that changing the precups will make any significant difference. EGT's are easy to control with pop pressure via injection duration, which enlarging the throat effectively does the same thing, just a whole lot more of a pain in the ass.

I will be putting 7.3 cups in my 6.9 heads when they come off for Orings, and comparing them at least for my own reference.