Normal or Not

[big_stroker]

I recently got a new job and have to drive 38 miles one way mostly highway with a few stop signs.

I have never really tried to get the most fuel mileage out of my truck so I decided I'm going to now.

The last few weeks while driving to and from work I have filled up and went 441.2 miles on 23.28 and came to 19.0. Yup I had to double check the numbers my self. So the next week I filled up again and went 424.2 miles on 24.11 gallons and comes to 17.6 (I had a weekend of more than just highway driving on this tank)

Before I never got this good of fuel mileage usually averaged 15 - 16 mpg.

I also noticed while trying to get the better mileage that with my mods in my sig I was able to cruise down the road at 64mph and have 0 lbs of boost and keep my egt's around 500*

Just wondering what most people with a 38r and hybrids are seeing for boost and egt's at cruising speeds.

 

[blackbetty13]

Well I'm getting around 13 with 238s and gt42 gearheads tunes as well however I have a couple of missing injectors either 1-2 so hopefully when the new injectors come in I can get the same

 

[Gearhead]

With ported heads and and stage 1 cam, boost dropped from 5-6 psi on the highway to 2-3 and egts went from 650 to 525-550 (am on 35s) and that is at 70 mph. The drop in EGTs can be attributed to the turbo's boost to drive ratio since you are running more CFM at the same boost level, the pressure drops and thus you see a reduction in drive pressure which will give you lower egts.

 

[big_stroker]

I'm on 35's as well Matt.

I'm guessing the big thing is the porting. I need to get my drive pressure gauge hooked up.

 

[Gearhead]

David did a good job with your heads. They are ported perfectly for a street truck.

 

[lincolnlocker]

i don't have hybrids but i see 0-1 psi below 60mph 1-2 psi at 65 and about 500-550 egts.... at 70mph i see 2-4 psi and 550-600egt. on flat to barely upgraded roads with the cruise set.

 

[big_stroker]

Do you have the 1.15 housing?

 

[my79f]

Maaaan i want to get mileage like that!!

 

[big_stroker]

Maaaan i want to get mileage like that!!

The main trick is to keep your foot out of it. Drive like an old grandpa. Shift at 2000rpm and dont let the EGT's get over 600*

 

[lincolnlocker]

Standard housing..

 

[Big Bore]

Do you have the 1.15 housing?

Which one are you running? I'm running the standard 1.0 WG housing but have the 1.15 and adapter that I'm planning to install here soon. I can get around 16 up here running the hills if I stay out of the throttle with the current tunes I have. EGT's are around 600-800 depending if it's flat or a slight grade, steep grades go up from there.

 

[JoeDiesle]

70 mph = 600egt, 2-3lb boost, 65-68mph = about 17-18 mpg.

 

[big_stroker]

I'm running the 1.0 housing that comes stock. I have thought about trying to find the 1.15 for the 38r and giving it a shot. But I need to hook my drive pressure gauge up 1st and do some logging with it and then do the housing swap.

 

[steele86]

your running a stock gtp38?

 

[907DAVE]

The main trick is to keep your foot out of it. Drive like an old grandpa. Shift at 2000rpm and dont let the EGT's get over 600*

Did this for about a month with my dually........its alot harder then is sounds!

 

[jwlandry]

your running a stock gtp38?

no. he has a 38r

 

[TrailerHauler]

Your truck certainly is a bit different from a lot of other peoples with similar setups, and I've always attributed the differences to the head porting. I think that makes all the difference in the world!

 

[TARM]

I agree fully. Between that and the tuning I think is why you end up with the results.