More PAWR without more fuel?

[Diesel]

Right now my engine and pump are 100% stock. I want to increase my low end power by having more boost come on at lower rpm but don't want to tuen up the pump or install bigger injectors. The idea is to boost mpg's by not having to push the pedal down further. I have a stock turbo. Isn't there a housing or something on the exhaust side that would allow more low end boost but not require more fuel? I don't want to run lean by putting in too much air without enough fuel. Or is that a gas truck issue only?

[oldestof11]

Lean? Diesel? Gassers want 14.7:1. Diesel are closer to 19:1...

No.

You want a 12cm2 exhaust housing. Helps spool quicker and make the truck feel lighter on its feet.

[Diesel]

And I can install this on a 100% stock truck? Where do i buy a good exhaust housing? Anything I should replace while I'm in there? Would a 12 be better on my stock truck than a 14 or 16?

[BILTIT]

http://www.pdrdiesel.com/products/PDR_D ... 37-27.html

[Diesel]

Thanks! So that will bolt to stock downpipe? Should I be doing compressor wheel as well as the housing or just the housing? My only request is that I don't adjust fuel or timing.

[oldestof11]

The 12cm is what you want. There isn't much difference between the 12 and 14. However, you never said what year your truck is? If it is a 92 with a 21cm housing, then the 16cm would be noticeable. If 89-91 or 93, then the 18cm to 16cm is not much of an improvement.

Get the 12cm alone. It will bolt right up to the down pipe. A larger compressor is not needed on a stock truck.

The fuel will come on quicker but nothing will be add above the stock settings.

[ellis93]

My 60mm compresser upgrade made a big difference in my truck. It along with the 14cm housing nets 27lbs of boost on stock fuel settings, even before the fuel pin.

[Diesel]

I'm sorry I have an inter cooled 1991.5. So just a 12 and I should get spool up sooner? What compressor wheel could I possibly use and who sells it (still at stock fuel settings)?

[ellis93]

Ya a 12 will get it spinning a LOT quicker, the down side will be that egt's can and will get out of hand towing. You'll have to keep one eye on it.
I bought my wheel from Gillet diesel service, I believe the spelling of their name may be wrong

[Diesel]

Ya a 12 will get it spinning a LOT quicker, the down side will be that egt's can and will get out of hand towing. You'll have to keep one eye on it.
I bought my wheel from Gillet diesel service, I believe the spelling of their name may be wrong

found them. Looks like I'm only doing exhaust housing. So if the 12 is good for low end so I don't have to push pedal as much, would 14 give me a better compromise of lower egt's yet good spooking and still increased mpg's? Also, for this to bolt up I want the "short" housing right?

[oldestof11]

MPG's are directly related to the right foot. Technically, your stock housing is the best as the boost doesn't come on sooner, hence the injection pump doesn't compensate as quick thus less fuel is added.

What it sounds like you might need is a 3200RPM spring... Nothing to do with adding fuel, just extending it.

[Diesel]

The reason I think this exhaust housing would give me better mpg's is because I won't have to push the pedal as far to get it moving. RPM's can stay lower with more torque off idle.

[delinquent]

I can sell you a whole turbo with the 12cm housing on it for half that. the shaft is broke in the turbo, but this would be a great deal for you. PM me if interested

[BILTIT]

The reason I think this exhaust housing would give me better mpg's is because I won't have to push the pedal as far to get it moving. RPM's can stay lower with more torque off idle.

What your not understanding is that when the turbo begins to build boost the injection pump adds fuel even though your right foot hasn't pushed the pedal any farther.

[oldestof11]

Here is your pump:



Right pic, you where it says smoke screw adjustment? On the side of the head there you cannot see is a hard line between the pump and the intake. As boost comes up, it pushes a rubber seal (so to speak) downwards which has a pin bolted to it.



As you can see, it is cone shaped. As it goes down, it gets deeper. There is a pin the rides along that "ramp". As it goes inwards up the ramp, it allows more fuel to be injected. The germans have a name for it shortened to LDA, translated means "fuel compensator". More air, more fuel.

If you want a touchier pedal, go 3200RPM spring. For quicker engine response, get the housing.

All in all, the max I have ever seen a truck get MPG wise, was 29 I believe. I can't remember if it was Jason (JQmile) or rbrettctd...

Jason has huge injectors, a 14mm head and rotor, S300 based turbo, 47RH trans for lockup, gear vendors auxiliary OD, and a 3.07 rear gears.

rbrettctd has either pods or 5x12's, getrag, 3.07 rear, and an HY35.

For more MPG's, get some slightly bigger injectors, rebuild the injection pump, advance the injection pump, rebuild trans, get a tighter converter or 47RH swap, taller rear gears.