How much restriction

[Redneckintraining]

How much restriction would a 12 CM non wastegated HX35 be on the engine at full RPM?I just drove roughly 135 miles,and according to the fuel gauge I used about 13 gallons of fuel.Speed was 65-75 (max speed with the 727).That is pretty bad.I know thats not accurate but it shouldnt need that much fuel.Would a NW 12 CM housing be that much of a restriction at max speed to cause that much of a drop in MPG?In the summer before it turbo died it got roughly 17-20 on the highway.I know the winter diesel blend drops MPG 2-4 mpg from what Ive heard.If thats the case than that would put me at 13 or so,only on the freeway Im getting about 10 which sucks.In town I am getting about 15.

[peobryant]

From what I have been told the automatics don't like the 12cm housings, (still not sure exactly why) but I don't think you would see a drop in fuel mileage. An HX-35 is a very good upgrade from the Non I/C "baby" H1C, so you may have a different problem.

[OLDEARL93]

I got the same mileage around 14 mpg when I put an x 35 12 cm wategated on my truck ,I still do have an answer, it did increase power band, or I should say raised the power band, if you find the problem let me know, I will probably switch back to the old h1c 18 cm, I have a 5 speed soit should of not been that bad

[Ace]

I would not attribute that to the turbo, think you got something else going on there. What's your boost and EGT numbers at cruise?

[Redneckintraining]

I would not attribute that to the turbo, think you got something else going on there. What's your boost and EGT numbers at cruise?

no idea I dont even have a tach

[mprmn08]

you need a tach to check boost and egts when your cruising??

[PToombs]

I think he means he doesn't have ANYTHING!

Bad! Bad boy!

Get some guages on there. It will help immensley to know what is going on with the engine.
Try to drive with your foot out of it. I know it's hard, but try it. See if the mileage goes up. I can't keep my foot out, and it shows in the fuel bill. It's sooo much fun though!

[Redneckintraining]

I cant drive with my foot out of it on highway.the truck maxes out at 65-70ish.Unfortunatly that is about what I am supposed to go on the highway.Gauges might be doable,However some time back the turbo on the truck died which is why it has a HX35.Back when its turbo was blown it got 12 MPG no matter what.There was a concern that it might have caused a scored cylinder.I am still trying to make sure it doesnt have a scored hole.with the new turbo installed it gets 15 in town but on the highway (in full boost) its getts crappy and smokes a little less than when the turbo was blown.In town, it only smokes if I get on it.On the highway however I can see a trail of greyish black smoke.

If it does indeed have a scored cylinder then my only real option is to just sell the truck and start again with something else.So right now I am looking for cheap ways to verify that the truck isnt broke.I am thinking if it isnt broke I will swap on a 16 CM housing and some gauges...

[PToombs]

This is why you need guages, perfect example. It hazes, if you knew how much boost you had, or the EGT's, you would have an idea how much fuel you're putting thru it.
Has anything been done to the IP? Maybe turn the starwheel up some for less fuel at boost. Has the air filter been checked or replaced lately? Fuel filter?
If it lacks fuel pressure, because of a plugged filter, or a bad LP, it will use more because it can't build enough pressure for a good pop. DPuckett found this out. When he switched to a piston pump, (his original was bad) His truck quit hazing and his mileage went up.

[Redneckintraining]

truck has a piston lift pump, and a BHAF that is about a month old.I am not sure what has been done to the IP but diesel shops around here have looked at it and said somebody tweaked with it because of the position of stops and levers and such

[PToombs]

You can try changing the fuel filter, but you should seriously think about a set of guages very soon.
You can try to cut back on the fuel with the IP settings if the filter doesn't make a difference, but with no guages you don't have a baseline to compare to.

[ontos]

This was my experience, and it dosn't mean I know a lot about your deal.
Not sure what turbo you had before.
I had a non I/C stock turbo with 50mm compressor wheel, fuel screw way in, EGT's would shoot up. Had too much fuel or too little air.

I called HTT about an upgrade, and searched info on a few sites. I wound up just changing the compressor housing and wheel. The new wheel was 58mm. had a good conversation with HTT about impeller size and was told that "too big a wheel' could be a problem. I think the reason was that forcing more air in than could be swallowed. (Again I don't know the real tech. reason) could reduce power.

I increased the size of the cross over and the air supply inbound.

The result was that I had more power at a lower throttle position and could really top out EGT's. Lost some MPG.

I backed out the fuel screw and returned to the same MPG with the same power, EGT's seemed to increase slower.

Long story longer, there are smart people here that can explain turbo flow and balance of air. I can't but I do know the 1st gen thing is about balance in the adjustments.

I drive by the EGT gauge.

[DTanklage]

If it does indeed have a scored cylinder then my only real option is to just sell the truck and start again with something else.

yea, there ya go.;...that will do wonders for your karma or reep what ya sow or what ever you call it

geez

dont sell the truck if that is all that is wrong with it

sure someone on here has a good short block for cheap

even i got one of those for sale!

don

[ford69557ci]

It has been my experience that the 12cm work great on a 5spd with a maxed pump, but runs higher egts and crappy fuel mileage on the auto truck. The auto keeps more of a constant load on the engine compared to a stick thats why the like the bigger ex housings

[Ramrod90]

When was the last time you adjusted your valves? If your valve lash is out of wack, it will drastically reduce your mileage. Mine hadn't been adjusted since the assembly line so I went a head and did them and gain a bunch of mileage. Just a thought.