Has low(er) mileage, aftermarket injector pump (vp107? or something) 3k gov springs, advanced timing,SB clutch......what's next? I', think'n of getting somekind of electronic truck programer (like a smarty jr. maybe) what's a good one to get? How much boost can I make safely on this truck as it stands right now??? Thanks

 

What year is your truck?
If it's really a 12v then there is no programmer for it. It's all mechanical.
The ip would be on a 12v is either p7100 or VE pump.

 

What's a good fuel additive to use? Should I use one? How often you guys change oil, filer, and fule filter in a 12 valve? What kind of mileage should I get unloaded?

 

You need to fill out your signature so we know what you have. Mileage depends on type of tranny, gear ratio, tire size. The additive I use is Stanadyne. I mix 8 oz. with a pint of 2 stroke low ash oil per tank. I change the oil every 3,500 but many people go longer like 5000. The fuel filter gets changed every 12,000. I have a BHAF and I tried to make it last 10,000 but I think thats way too long to wait. I think its better off being changed around 6,000.

 

Programmer on a 12 valve, hmmmmmmmmm. Let us know how that works. Guess you could upgrade to a VP44 on a 12 valve .

Absolutely nothing wrong with a 12 valve, in fact knowing what I know now, I would have stayed with 12 valvers. Our electronic success rate seems to be somewhere around 50% or so. Of course like one of the engineers here always says, HP up = reliability down.

Just so you know, electronics will not attach to your engine and give you the expected result you desire. Everything you do to that engine involves swapping parts out (bigger injectors, bigger turbo, etc).

What's a good fuel additive to use? Power service, Stanadyne, pick one that says diesel
Should I use one? Your choice
How often you guys change oil, filter, and fuel filter in a 12 valve? 25000 miles on the oil, 5000 on the oil filter, 80,000 miles on the fuel filter (but of course I run the Amsoil dual remote and the FASS system)
What kind of mileage should I get unloaded? 14 to 25

OH, welcome to the site too.

 

Thanks. It's a '94 5spd manual reg cab long bed, VP7100, BHAF, 3k gov springs, South Bend Clutch, Boost & Pyro gauges. It's that blue one that was posted in the classifides on this site couple a days ago. So is there any way to increast mileage without hurting power? I'm getting like 17 mpg highway unloaded. What's the highest boost I can safely make? The guy who sold it to me said keep it under 30 psi, but the truck builds more boost than that. What should be my boost red line?

 

As far as mileage goes it sounds like you have a 4:10 gear and if thats the case you are prbably tapped out as far as mileage. If you have the 3:55 gear you can bump the timing up and get some different sticks and get around 23 or better. You can do that if you have a 4:10 too but I doubt you'll get much better then 18 or 19. That low gear just runs the rpm's to high to be fuel efficient. I know because that is what I have. It's great when you are pulling a trailer though. I like the 4:10 better. I have had both. With the 4:10 gears I have no problem passing another vehicle when I'm towing. Down side is the mpg's.

 

If you like the 4:10's, you could go with a Gear Vendor overdrive. My sons truck had one and it was sweet. A bit pricy but very nice.

 

Drop the 'V', it's only P7100. About 34 psi is the max efficient boost, higher than that and you're blowing hot air around, and the drive pressure is higher than 1 to 1. The little HX35 has been pushed very hard, you'll find many guys talking about 50+ psi of boost. It is possible, and they can stand up to it, but it make no sense. At that point, you're probably talking 70 psi or more of drive pressure, not to mention the heat. Keep it down to a reasonable level for reliability.

 

check the tag on the turbo and make sure its not a WH1C and not a hx35. the 94' and some 95' model trucks have the wh1c, not the hx35. the only reason to worry is if you wanted to upgrade the turbo if it hasnt already.