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View Full Version : '93 mechanical pump - how much boost?



DP
11-15-2004, 09:03
I finally hooked up the boost gauge. Now maybe I can get serious about troubleshooting my low power, low milage, high egt, too much smoke problem. If I load the engine against the brakes, i.e. not moving, I can get almost 6 psi before wheelspin. This produces a bit of smoke (out of the pipe, not off the tire). While going along at about 55, if I add throttle, using the brakes to maintain speed, it will get up to about 8 psi until the downshift into third then it drops to a little over 5 psi. It didn't seem like a great deal of smoke was emitted and egt stayed below 1000 (pre turbo). The road traffic and brake temps wouldn't allow me to do this rolling test for more than about 5-10 sec. so I would guess that egt's could go up more.
I'm not going to have a trailer hooked up again until March (race season is over). Any ideas on what could be causing my problems?
Truck has 190K and I believe, but don't know, that the timing chain was replaced before I got it at 125K. Should I start with injectors and go from there? Are hi-pops worth the 2x cost? If I have to eventually change the pump, can I go to the 250 hp level with water injection and no intercooler?
Thanks in advance.
Dave.

DP
11-16-2004, 04:30
Just moving this subject back toward the top. Are these boost numbers normal? Any input about the injectors?
Thanks, Dave.

More Power
11-16-2004, 07:33
Your boost pressures sound like they're somewhere in the range of normal. However, I'd suggest just doing a wide-open run to 60 to test for boost pressures. Should see a 7-10 psi peak at about 1800-2000 rpm, then it'll fall off as rpm increases beyond that. A 0-60 would also allow you (us) to evaluate power, in relation to what is in the normal range for a stock 6.5.

When was the last time the injection timing was checked?

You can measure the slack in the timing chain by removing the oil fill pipe, then rocking the crank to determine how many degrees of crank rotation is required before the gear on the injection pump begins to move. Up to 3 degrees is normal. If you're seeing 4 degrees, it's time for a new timing set. A new timing set (either chain or gear) produces about 2 degrees.

MP

DP
11-16-2004, 09:05
Timing has never been checked or changed in the 5 years that I've owned it. I'll try the trick of looking down the fill tube. I don't think I'll get more than about 6 psi during a 0-60, the only way I was able to get much higher than that was by loading it against the brakes.
Thanks,
Dave.

More Power
11-16-2004, 11:19
You'll need to remove the oil fill pipe to see the gear on the injection pump.

www.heathdiesel.com (http://www.heathdiesel.com) sells an adjustable wastegate actuator called a Turbo-Master that you can use to dial-in the desired boost pressure. Price is right also....

MP