6.9, 7.3 N/A, or 7.3 IDIT long block for hi-po build

[PwrSmoke]

I played on the dyno with my old 6.2L GM and found that it gained a little by advancing it a touch from stock but at a certain point, about 5 advanced from the stock non-emisssions setting IIRC, the numbers started to drop (and the engine got VERY noisy). I did that with no other changes and with an NA engine, so I don't know how valid it is to this discussion. I think I left it about 2-3 advanced until I finally turbo'ed it and changed all the calibrations to suit. Interesting discussion here!

 

[IHOlRed]

dont know if anyone has said this yet but what about usin a db4 pump in place of the db2. you wouldnt have to worry about running out of fuel

 

[Jake S.]

It seems that it is a matter of the db2 not have the right timimg curve for the high rpms. Dyoungs is advanced at low rpms, but might be close at higher rpms. Someone has to work with a pump builder to correct the timing for the rpm. We are proving that the motors can turn the rpm, so far. But do they make more power? we need to see that on paper.

 

[kas83]

I played on the dyno with my old 6.2L GM and found that it gained a little by advancing it a touch from stock but at a certain point, about 5 advanced from the stock non-emisssions setting IIRC, the numbers started to drop (and the engine got VERY noisy). I did that with no other changes and with an NA engine, so I don't know how valid it is to this discussion. I think I left it about 2-3 advanced until I finally turbo'ed it and changed all the calibrations to suit. Interesting discussion here!

Thanks for posting. I've mentioned, either in this thread, or another, that advanced timing has diminished returns after a certain point. It stands true with almost any diesel.

And Jake S got it right also. A pump shop will have to fine tune the pump, play with it quite a bit, to get it to keep up timing wise on the highend.

With a DB4, what's the injection rate compared to a DB2? If it can put the fuel out faster, even if it can be at the same volume, it will help in power production. With a higher injection rate, the timing curve can be slightly relaxed, as it can keep up with the burn rate at higher rpm when moving fuel faster.

 

[david85]

It seems that it is a matter of the db2 not have the right timimg curve for the high rpms. Dyoungs is advanced at low rpms, but might be close at higher rpms. Someone has to work with a pump builder to correct the timing for the rpm. We are proving that the motors can turn the rpm, so far. But do they make more power? we need to see that on paper.

I think you hit the nail right on the head there. I remember some one on FTE wanted to make a custom pump for the sole purpose of improving the timing map. He never did but his ideas seem to agree with Dyoungs experience and and we know the moose pump is limited to 3000 RPM because of the timing limitations of the DB2.

I guess that means the timing swings too far to the retarded side when the engine is near its rated power. That doesn't sound very ideal.........

....if we are right about the timing map, that is.

Interesting discussion indeed

 

[Jake S.]

It seems that db2 has a fixed amount of advance, and so only a fixed amout of rpm to work with. With a stock pump anyways. Mel would know more, as he has worked on timing with the moose pump.

 

[dyoung14]

i wonder if i unhook the arm on the side of the pump that retrds timing if that will do anything to benifit

 

[david85]

i wonder if i unhook the arm on the side of the pump that retrds timing if that will do anything to benifit

The plunger at the bottom end of that arm would pop out if it were not for that arm holing it in place. The cam at the top end could be rotated or modified to have a flat profile though. That would give you a disabled side arm without risk of the plunger popping out.

I have no idea if this is wise to even attempt however.

 

[dyoung14]

The plunger at the bottom end of that arm would pop out if it were not for that arm holing it in place. The cam at the top end could be rotated or modified to have a flat profile though. That would give you a disabled side arm without risk of the plunger popping out.

I have no idea if this is wise to even attempt however.

what could possibly happen?