Quote:
Originally Posted by tasdrouille
Something does not add up. You can't just add more air and make more power, you have to add more fuel too, and the stock fueling system will only flow so much.
Careful with this DIY boost mod. Have you looked at the compressor efficiency map for your turbo? With increasing boost you have to carefully watch what you are doing. There's a reason the stock boost limit is where it was set at by the manufacturer. If you push it too much too early, or at too high rpm, you'll grenade your turbo, especially at your altitude.
The 55 mpg on the highway seems high. You should make a fuel log and look at the long term trend.
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This is a completely mechanical fuel system and adjustable, mechanically. You have to think in non computer terms here on the entire system, throw that out the window. There are no turbo timers because there is no computer. There is a massive mechanical fuel pump, and a turbo, and waste gate, and a motor. I increased fuel delivery by doing what I stated in the short blurb. Basically, I increased the timing the low speed circuit on the pump lasts so the transition wasn't as much of a lag between the low side and high speed circuit. I also removed a restrictor that disallowed the high speed part of the fuel circuit from giving the injectors max fuel flow. EVErYTHING stock on this truck was limited so the factory didn't have to replace yet more engines than they already did because of a bad original rod bearing design. In fact, my engine got replaced free by the dealer with a brand new factory motor in 1990. I had to do about 3 months of research on the net and asking a handful of people who had this truck or a car with this motor in it to find out what they did to increas hp. Plus, do you know anything about diesels? The first thing to do to build HP is un-restrict the air intake and exhaust. That alone even without touching the fuel delivery...or turbo will garner sometimes 10% increase in HP because of the stifled factory desigins for intake and exhaust noise.