bikeboy1713

I have a stock truck (see sig) I am new to the cummins so I am not sure where I should go first. I just ordered a 3200 RPM spring from PDR. When I put it in I will turn up the fuel screw a little. That seems to be a no-brainer. The next thing that I am thinking about doing is changing the turbo housing out from a 18.5 to 16. Will this make much of a difference, or should I spend my money somewhere else?

Underpsi

From my personal experience of being a fellow 18.5cm housing owner and doing the swap to a 16 I wish i hadn't spent the money on it and spent it else where.
reason
1. I didn't notice a $200 difference
2. Im serious about bombing my truck (translation - stock turbo ain't staying anyway)
3. hmmm I dunno 3 maybe I regret wasting my money on it now cuz I know im gertting a different turbo and I could have put that 200 to better use. AND NO it has nothing to do with 1 or 2

DBF

A 91 W250 with 20,900 miles? Where has this truck been?

In any case, add the gauges you'll need *before* you do the mods so that you know the effects of each mod as you put it in.

The gauges the group has found most needed are:
1. Boost - intake manifold pressure
2. EGT - exhaust gas temperature measured in the exhaust manifold
3. Tachometer - shows engine rpm
4. Automatic Transmission Temperature - critical for these 727/518 as you add power. Heat is the big enemy of auto transmissions.

After you've installed these gauges, you can change housings and actually see how much it bought you in terms of boost and EGT, and how much it might hurt you in terms of trans temp. Same for the 3200 spring. Same for turning up the fuel screw.

The biggest bang for the buck will be the spring and the pump tweaking. The critter should scoot nicely. But I know the trans will experience higher heat as you stomp the thin pedal with the pump tweaked up. I think it will experience higher heat at the upper rpm >2500 but I'm not sure of this one; someone with that spring in an 88-91.0 will have to take that one.

Pump-tweaks and 3200 rpm springs are cheap but transmissions are expensive.

Have fun with your truck - it should last a long, long, time.

DBF

wannadiesel

Unless you spend most of your time in local traffic or live at high altitude, I don't think the 16 cm will benefit you much. If most of your driving is highway, keep the 18.5, especially with the 727.

bikeboy1713

Got the truck from the original owner, a retired Boeing engineer. He drove it about 1000 miles a year, but he did all the maintanace, oil changes etc. I am LOVING the truck. Runs and drives like a new truck. The truck has a tack, EGT gauge, and a vacuum gauge...Don't know how much help the vacuum gauge will be. I guess from reading your post that I should get a trans temp gauge next. Should I get a boost gauge if I am not changing the turbo? How about a fuel pressure gauge. From what I understand, the fuel pressure gauge measures the pressure between the lift pump and the injection pump. Is the only reason to do this to monitor the health of the fuel filter/lift pump?

BTW this website is a great resourse. I hope that I don't drive you guys nuts with dumb questions while I am learning the ropes

Thanks in advance
Don

wannadiesel

I would replace the vacuum gauge with a boost gauge - no vacuum on a turbodiesel. The boost gauge is fun to watch and it can help in diagnosing problems or tuning for power. A fuel pressure gauge is not mandatory. We don't have much trouble with our lift pumps, and the stocker is fine for trucks with stock injectors. You're right that it can be a good diagnosis/fuel filter change indicator tool. I like mine.

The 1st gen group is a pretty friendly bunch. It's a front we put on so we can lure you to the edge of the ol' slippery slope of "more power" and then we give you a push.

rebal

I dont think I would bother with the 16cm either ,My vote would be for a good used HX/35w and mod the down pipe to get it on there . that will give you quite a noticable inprovement in the way your truck will responed to the movement of your right foot. just my .02

PeytonMaterne

I went from a 21 to a 16, and noticed a little change. But from the 18.5 to the 16. I don't think you could tell much difference especially on an automatic. I would keep it.

90firstgen

I upgraded from the 18cm to a 14cm from an HX-35. And YES, I did feel a difference. The exhaust housings are completely compatible on the H1C and HX-35. I got mine off of e-bay for about $200 bucks. Well worth the money in my opinion....helps keep everything cool too after turning up your pump.

cLAYH

After I turned my pump up I upgraded to a 16cm housing and noticed about the same difference in power as turning up the pump did as well as a way faster spool up. But that being said it wasn't long before I went to a 12cm housing. Might save yourself a step and figure out what you'll be doing with the truck and where you want to go with mods and just bite the bullet and get what you want.