boost drop

[1992gen1_fan]

How much boost drop is normal with a M&H timing spacer plus 1/8" bump? I installed the spacer quite a while back, with the pump at the "stock" timing mark there was'nt a notable difference in boost. I recently bumped the timing about 1/8" to get rid of haze seemingly very retarded timing and now the turbo does'nt spool near as quick and also the boost is'nt as high. During normal everyday driving I don't see over 10psi unless I pull a good hill at highway speed ect. On flat ground cruising at 60-65 mph, the boost is about 2psi where it used to cruise at 5-8psi and easily go to 12-15psi with a little more throttle.

I hav'nt found any boost leaks.

It does run alot better and cleaner with egt's about the same, maybe a tad lower with the 1/8" bump so I'm not complaining. But I'd like to know if it sounds normal. Thanks

Thought I'd add that I have 2 boost gauges and they're consistant with the boost drop, so not a gauge problem.

[RCCUMMINS89]

Normal

Just as long as it drives better all the way around, I'd leave it.

It's hard to guess what kind of boost and egt drop will actually happen. But, I can gain or lose upwards of 20 psi of boost with my setup just by changing timing.

[1992gen1_fan]

Good to know I guess I'll see how it does when I install the lpplp.

[RCCUMMINS89]

Most (probably 95%) seem to notice a more responsive throttle, about half notice more wot power.

What pump did you go with?

[1992gen1_fan]

Got one from you, ( im w350_1992 on CF). The day the LP came in the mail, my fuel psi gauge broke. I expect the new gauge within the next week or so, then I'll install the LP. Can't wait.

[RCCUMMINS89]

Keep me updated.

[1992gen1_fan]

Ok, I will The new fuel psi gauge gauge came in today so the new LP will be installed as soon as I get time.

Today I checked the boost numbers. Looks like in 3rd gear accelerating up hill its about 8-9 psi max and hard acceleration in 5th about 18 psi max with the water/meth running. I'm thinking I've seen about 28-30psi max before.

[1992gen1_fan]

I adjusted the water/meth controller to turn on at 8psi instead of 12. Helps quite a bit. I think I'll adjust the turbo just a shade tighter also. The lack of boost/late spool-up is getting a little annoying. It runs fine but if I need to pull into traffic it'll black smoke a fair amount unless I get on it enough to spool the turbo to clean it up.

I'll see what a small adjustment on the turbo does.

[RCCUMMINS89]

Tightening up that turbo should spool as quickly as you need it to.

I've seen where others say that they can build boost at an idle with the right adjustment.

[1992gen1_fan]

Yea I think it will help alot. A little adjustment makes a big difference with these turbos. You can make it spool super quick, but it'll also be restrictive at take off, just gotta fine tune it and find a good ballance (the sweet spot).

[1992gen1_fan]

I adjusted the turbo, turned the adjustment screw about equivalent to swapping a 19cm housing to a 18cm. That helped alot.

[RCCUMMINS89]

Good to hear............nice thing about these turbos, is if you have the patience to tune them.....you can make a smoke free (or virtually smoke free) driver.

[1992gen1_fan]

Yup, the main reason I had it open so far is because the drive pressure gauge line plugged up. Got that fixed also now