Question for Dieseldummy

[84 Convert]

Sooo I have a turbo installed now which totally cleaned up the smoke from the '4911 pump... how much have you turned the fuel screw? Just kinda curious what it takes to pull off what you have. I do not currently have an I/C installed or the holset turbo, but I am looking in that direction.

TIA

Gregg

[dieseldummy]

Until you get intercooled I wouldn't go over 1/8 turn over stock. Intercooled with a better turbo I run a maxed out pump and can hit 1250 on the pyro towing heavy. I guess it depends on what you are planning to do. If you just play around on the street you can probably go more on stock parts and drive by the gauges, but if your towing 1/8 will be plenty.

BTW, How'd that piston deal turn out?

[84 Convert]

That was kinda what I thought. I currently cannot get it over 1100 pre-turbo on a good hill with a 6000 lb enclosed trailer which I tow more often than not. How far is maxed out? I think I saw 3/4 turn somewhere is that correct?

I'm seeing 7psi with spikes to 10 on a GM3 turbo. It also looks like boost falls off as it get wound up. I'm gonna try a home brew turbo-master but I'm betting that flow capacity is the limiting factor on this one. I won't be looking for more than 10-12 psi constant. It is still alot better than NA 6.2!

Thanks

Gregg

[dieseldummy]

Is that with the stock boost canister on the GM3? If it's like most GM3's I've been around 10-12psi will be the most you can get out of it. Never could get 15 out of mine... 1100 leaves some room for adjustment. Not much though. Depending on the leafspring in the pump maxed out is +/- 1 turn of the fuel screw.

[byte]

if you were using a good pump (lots of psi)... how much extra fuel do you think 1/8 of a turn would boost the pump output?

[HH]

Is that with the stock boost canister on the GM3? If it's like most GM3's I've been around 10-12psi will be the most you can get out of it. Never could get 15 out of mine...

I have got 14 - 15 psi peak out of my GM3 going uphill or merging into traffic while towing. In the future I want to replace it with a GM8 and IC.

[john8662]

The 4911 really only has about 1/2 turn left beyond factory settings.

I've got mine maxed out on my '82 pickup, and with the boost at it's current settings, I get little to no smoke once spooled and my 11US on the floor.

J

[84 Convert]

Looks like all I'm gonna get is 10-12 psi. My fuel economy has actually increased. I am a little leary of turning up the pump for this reason. I have a heavy foot and I'm guessing that more fuel available will be more fuel burned.

That said, what kind of fuel economy are those of you with a -4911 pump turned up getting when you approach 14K GCW? My current MPG looks to be somewhere around 14.5 +/-. (with trailer in tow)

Gregg

[john8662]

Looks like all I'm gonna get is 10-12 psi. My fuel economy has actually increased. I am a little leary of turning up the pump for this reason. I have a heavy foot and I'm guessing that more fuel available will be more fuel burned.

That said, what kind of fuel economy are those of you with a -4911 pump turned up getting when you approach 14K GCW? My current MPG looks to be somewhere around 14.5 +/-. (with trailer in tow)

Gregg

14MPG pulling is really good.

Most get around 11-12MPG pulling, my 6.2 with Banks got 16 MPG pulling a 2 door tahoe on a trailer for many miles, not a heavy as what you're pulling.

But, I don't think DD's truck ever gets close to 14 MPG empty :rolleyes:

J

[dieseldummy]

Jeez John, give me a break... I got 15mpg this tank. Honestly though, that's as good as it gets for me. Before the big tires I could muster around 17-19 driving carefully. Never got over 10mpg towing though. I'd be thrilled with 14 towing.