added benefit of the HX40!? MPG is way up!

[Forrest Nearing]

with the stock HX35/12 I was averaging about 16mpg around town and ~18 on the highway



with the HX40/16 I'm seeing ~18 in town, and I haven't calculated highway consumption yet, but the needle is moving A LOT slower!!!



now, I attribute much of the around town consuption to the fact that my AFC is all the way forward and the star wheel is adjusted all the way out, and the HX35/12 was so quick to spool up and it would just dump fuel like crazy unless I absolutely nursed the pedal.



but getting the cork off the turbine side is really letting the engine breathe easier. I drove up to OKC last night, and I hardly ever had the boost needle any higher than ~3-5psi. most of the time it was at zero, and on a couple hills I saw 10psi in order to maintain speed. average speed on the speedo was ~72mph, but it's a little off because of tire height.



when getting ~18mpg, I would go maybe 330 miles before half a tank... with 200 city miles already on the truck when I headed out, I was showing 375 miles at half a tank! I was going to fill up before I left, but diesel is so much cheaper up here! LOL!



admittedly, I WAS watching the boost gauge trying to keep it down and there was little traffic, so I was able to maintain a steady throttle position/load (slowing slightly going up hill, speeding up going down hill) but still... 2mpg in town is pretty substantial IMHO!! Oo.



Forrest

 

[moparguy]

So..... has the wife seen this post yet?



Good thinking;



"Honey, this thing will pay for itself in fuel savings!"



RJR

 

[jimk]

Originally posted by Forrest Nearing

with the stock HX35/12 I was averaging about 16mpg around town and ~18 on the highway



with the HX40/16 I'm seeing ~18 in town, and I haven't calculated highway consumption yet, but the needle is moving A LOT slower!!!



now, I attribute much of the around town consuption to the fact that my AFC is all the way forward and the star wheel is adjusted all the way out, and the HX35/12 was so quick to spool up and it would just dump fuel like crazy unless I absolutely nursed the pedal.



but getting the cork off the turbine side is really letting the engine breathe easier. I drove up to OKC last night, and I hardly ever had the boost needle any higher than ~3-5psi. most of the time it was at zero, and on a couple hills I saw 10psi in order to maintain speed. average speed on the speedo was ~72mph, but it's a little off because of tire height.



when getting ~18mpg, I would go maybe 330 miles before half a tank... with 200 city miles already on the truck when I headed out, I was showing 375 miles at half a tank! I was going to fill up before I left, but diesel is so much cheaper up here! LOL!



admittedly, I WAS watching the boost gauge trying to keep it down and there was little traffic, so I was able to maintain a steady throttle position/load (slowing slightly going up hill, speeding up going down hill) but still... 2mpg in town is pretty substantial IMHO!! Oo.



Forrest

Sir do you think that the afc housing settings or perhaps the use of the boost gage the get the good mileage. I have read where some guys get poorer mileage with a bigger turbo when towing. Interesting enough the first generation had a very large exhaust housing, and most got good mileage. I have all ways wondered if drive pressure reduction would net more hp? What is the best turbo (single) for towing and good mileage with about 350 hp and a standard transmission? Thanks for any ideas. Jim

 

[Forrest Nearing]

I'm 26, PLEASE don't call me sir! LOL! well, I think use of the boost gauge helps the most... I think if my AFC was tightened up with the stock turbo it would have been easier to keep from getting into boost so quickly... I'll admit that I'm driving the truck "softer" now, but it's so much easier to do so with the bigger turbine side. before with the stock turbo, if I just accelerated very soft and easy away from a light with just enough throttle to keep the truck at a steady 2000rpm in 2nd gear, the truck would make 15psi... it makes none now.



don't get me wrong, if I lay into it, the truck makes 40psi and hauls bauls but it's just much smoother and easier to drive now.



I'd probably go with one of the 40/35 hybrids with a 14cm wastegated housing.



I would have done something different, but I've only got a few hundred dollars in this turbo... I wish it spooled up a little quicker, but hopefully the TAG will help out some.



forrest

 

[RDietze]

Originally posted by moparguy

So..... has the wife seen this post yet?



Good thinking;



"Honey, this thing will pay for itself in fuel savings!"



RJR

may as well save your breath!

 

[Forrest]

But honey, I'm gonna sell the old turbo

 

[dpuckett]

jimk,

I think the reason the first gens got such good MPGs was a combination of being lighter (roughly 1000#- my 91 is 5100 w/ full tank and me in it), and making less HP, and not being designed to be as fast as say a 96 with a 215 pump. The housing size does seem to make a difference in spool up and MPGs. I have yet to drive a full hwy tank with the PDR 35-ported 12, but I didnt really gain any MPGs with it vs a ported 18- still in the 18-19 city range. It goes WAY down if I have to put a bunch of ricers in their place in a week. . I, too, have trouble keeping it under 15 psi. Mine will make 40 psi, too; does that mean I'm near Forrest's HP level? Dont hardly think so.



Daniel

 

[Cooker]

I have talked with at least one other TDR member who picked up MPG's going to a 40. He said he consistently get't 2 MPG's better on the highway than his modified HY35 used to net him.

 

[CumminFast]

long live the 40!!!!