MPG and how to gain some....

[scoobert]

ok, this may sound crazy, but i deliver newspapers with my 6.5TD in a 1995 suburban. i get from 12-13MPG now stock with 220K...

what improvments have you folks seen with the 40HP chip, exaust? and what else?

i am looking to maximise my MPG, i figured if i dop the cat and do a downpipe that should help, then add a 40 chip? i am only concerned about MPG as i go 200-300 miles per day. thanks!!!

[christja]

continue out with the exhaust but drop the muffler too. I dont have either now and im getting 16-18mpg. You also want a new air induction kit, get rid of the stock box.

[Steve4]

Just my opinion, but for me, I have found the starting place for ANY kind of improvement on the 6.5, mileage, performance or otherwise, is the Air Induction and Exhaust. Air in - Exhaust out - You WILL see an increase.:)

[94sub]

If you saw your stock downpipe outside your truck you would wonder how you ever developed any power. It looks smashed, crimped and beaten with a hammer, but that's how GM wanted it, for whatever reason. The replacement of your exhaust will make a huge difference and adding a performance intake will take your truck to the next level.

[Garth J]

I found out the reason for GM squashing the down pipe is that when they build the trucks the engine and exhaust are allready in the chasis and the body wont fit with the pipe not being in that shape. So im told

[scoobert]

on the downpipe bent rumor, i have heard that they install the downpipe and then put the motor in the truck, when the motor goes in the downpipe gets squeezed....

i need some quiet, i deliver at 3AM, what would you tip me if i came "rapping" by at 3AM?

i might just stick with 3" and put a high flow muff on it. and downpipe for sure.

all the air intakes are overpriced.... i can get a cone filter for $75 and i wonder if that will just slide in the elbow?

what is that pipe doing that comes from the valve cover to the intake? PCV?

will getting rid of the EGR add horsepower?

does this truck have a speed governer at 98?

[Chevylover]

i need some quiet, i deliver at 3AM, what would you tip me if i came "rapping" by at 3AM ?

If you use only the downpipe and the oem cat and exhaust system it wouldn't be "rapping" as you think. As i bought my truck, the first i did was to remove "everything" after the cat but i got no "sound". As i removed the cat, the truck "roar". So i want it loud and installed a 4" system.



all the air intakes are overpriced.... i can get a cone filter for $75 and i wonder if that will just slide in the elbow ?

That my opinion too. I bought a filter element that fits the oem airbox. Than i removed the snorkel in the fender, drilled about 10 hole in the airbox on the "dirty" side so that the air have to go through th filter and modified the airbox as metioned as on the kennedydiesel site. I can hear the turbo scream, the engine gets more and cooler air because it comes from outside the engine compartment.


will getting rid of the EGR add horsepower ?

I removed the egr system on my truck and i think it is going better without, because if you don't run the egr system the engine only gets fresh, clean air and not the "used" air from the egr. You got a 1995 engine with a "S" engine code. Remove the hose from the egr valve and put a screw or something else into the little hose at the egr solenoid where the hose goes to. No problem. After 1996 you will get an error code, before not.



what is that pipe doing that comes from the valve cover to the intake? PCV ?

Gas engine -> PCV Valve
Diesel engine -> CDR Valve - Crankcase Depression Regulator



does this truck have a speed governer at 98 ?

Mine doesn't. It makes about 190 kph - checked with GPS because the speedo ends at 160 kph.


Cu,
Sven

[scoobert]

thanks for the info, where is this site about modding the airbox?

i wonder if just the USA version is limited? afterall you have the autobon, we have lawyers....

i plan to remove the cat, after 220K i assume it would be somewhat clogged... this should help with airflow alone and then the downpipe wow.

i was also thinking of tinkering with propane, they say if you run it at low psi you get beter MPG

[Chevylover]

[QUOTE=scoobert;1133]

thanks for the info, where is this site about modding the airbox?

i wonder if just the USA version is limited? afterall you have the autobon, we have lawyers....

i plan to remove the cat, after 220K i assume it would be somewhat clogged... this should help with airflow alone and then the downpipe wow.

i was also thinking of tinkering with propane, they say if you run it at low psi you get beter MPG






Check your Mail or PN. I mailed you the link to the site !

What about the joke ? Tell it here or per mail.

Cu,
Sven

[scoobert]

but yeah i will be upping the exaust size a bit first to se if that helps with MPG i may also pick up a passat to help with MPG too, 40MPG on diesel sounds tempting.... i was browsing that other site it looks interesting. not well laid out thou. but thatnks for the info.

[njdevi11]

Hands down the best way to get better fuel economy is to regear. You can easy improve 25% by switching from 4.'s to 3.'s

[sixnickel]

After we do all performence upgrades. More air in ,more fuel in ,more exhaust out, play with timing the next thing is RPM. If you can get them to cruise about 1800 RPM thats where you should get the best MPG. Gears.ODs. Tires do what you got to do to get the RPM down. My 91 V1500 Burb with a Banks 6.2 . 3.42 gears, 700R4(.70od) 31" rubber 1800 RPM at 75MPH gets 23 MPG. If I could get the transmission to upshift properly at WOT I think it would blow the doors off both my 6.5s in the 1/4 mile! This things GOES!!
It also has 6.5 heads,6.5 turbo injectors and 20 to 1 ceramic top Diesel Depot pistons.

[Husker 6.5]

After we do all performence upgrades. More air in ,more fuel in ,more exhaust out, play with timing the next thing is RPM. If you can get them to cruise about 1800 RPM thats where you should get the best MPG. Gears.ODs. Tires do what you got to do to get the RPM down. My 91 V1500 Burb with a Banks 6.2 . 3.42 gears, 700R4(.70od) 31" rubber 1800 RPM at 75MPH gets 23 MPG. If I could get the transmission to upshift properly at WOT I think it would blow the doors off both my 6.5s in the 1/4 mile! This things GOES!!
It also has 6.5 heads,6.5 turbo injectors and 20 to 1 ceramic top Diesel Depot pistons.
My 94 C2500 HD 14 bolt 8-lug has 3:42 gears according to the axle code, a 4L80E, and LT245/75-16 E tires. On the Interstate in overdrive with the converter locked up it indicates 2750 RPM at 83 MPH (computer limited). Either someone installed a way deeper ring and pinion in my diff, or 1.5" of diameter makes a huge difference in RPM (which it doesn't). I think on its next scheduled major lube, while the diff cover is off, I'm going to count teeth.

[sixnickel]

I have a calculator program in my computer for RPM. You put in all your numbers for overdrive, gear ratio and tire size and it show what RPM you should be at. The program shows 60, 65, and 70 MPH. With 3.42s, a 4L80 with .75 OD and 245/75s, you should be running 1984 RPMs @ 70 MPH. I have found that the tachs in these things aren't very accurate. They are driven by the AC wave out of the alternator. A lot of aftermarket reman alternators have the wrong size pulley on them to make them turn faster and put out more amps. This will throw the tach off. On my son's 94 burb, his tach is way off also even after we put the correct pulley on it. If you can connect a skan tool to it, that will give you the true RPM because that signal comes from the Crankshaft Position Sensor and that signal comes through the ECM. Probably the best way to get a true reading, is stick with an original Delco reman for the application.

[Husker 6.5]

Hey sixnickel, thanks for the info. I've been up all night (too much coffee at the reception last night, oops!) I know the long formula for finding that , but my brain's too foggy! I did the simple algegra, and extrapolating for 83 MPH your numbers come out to 2350RPM, 400 lower than what my tach says. The ol' ear tach says it sounds like my engine is winding as high my tach says it is, I do have a lot of seat time in CUCV's, but what you say about alternators may be dead on. I don't know the origin of the alt on the truck when I bought it, but I replaced it two years ago when it died with an O'Reily's Auto Parts unit. The indicated RPM's were the same for both. When I get the engine rebuilt I will check it with a scan tool. Thanks.

[scoobert]

i have a 95 burb 8 lug and i cruise at 65 at 2100RPM, doesent seem right, i do have a 140 amp alt thou. he he he, i run all night with the heater on full blast, the abs going nutz and all the lights are on.
maby my tach is off? but at 55 i get about 1600RPMs

i know my tach likes to stick thou, sometimes it will stick for about 200 RPM's you can see it stick now and then, dont know why.

[christja]

I run 2150RPM at 65/70. What would make the Tach get off? How do i fix it?

[dieselturbo]

i have a 2500 95 suburban with 3.73 . 2000 rpm at 62mph - 15-16 mpg.

[christja]

i have a 2500 95 suburban with 3.73 . 2000 rpm at 62mph - 15-16 mpg.

At last check (today) im getting 13 mpg :(