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View Full Version : Yipee. What a kick. Found some of my missing balls.



Randee of the Redwoods
08-24-2003, 12:18
If you don't recall, I mentioned a while back when I got my truck that it was gutless going up hills, almost to the point it would slow. By the time I reached the top, I could easily be 10mph slower then what I was at the bottom, the tranny would NOT downshift, and the pedal would be a good halfway to the floor. As per someone's suggestion, I disconnected the downpipe from the cat and went for a drive.
Wow.
Aside from the noise, this truck did something it has not done in the month or so since I've had it: rev to 3000rpm. Doing 70mph on the interstate, I can make 2500 rpm, but going up a hill at slow speed, I'd be LUCKY to hit 2100 and that's giving it a lot of effort. With the exhuast opened, I had no problem maintaining not only 2500rpm+going up a steep grade, but my speed stayed consistant and looked to be increasing. The biggest noticable difference was the engine's willingness to rev. 2500rpm and even 2700rpm shifts were easy and smooth as butter(the low fat kind) and didn't take any more pedal than usual. On a flat grade, I experienced "scoot". You know...when the vehicle gets up and just goes. I'm tearing at the walls now for that Heath exhaust now. Gotta pay them bills so I can play.
I'm also sure this little experiment worked wonders for the egt's, too.
I also noticed something else: turbo whine. Sweet sounding whistles and screams of the rumored GM4 turbo which I had never heard before and was beginning to wonder if it was even really installed. For the brief moments I rode around the block, my truck finally sounded like a truck.
I also found something very interesting of note. While inspecting the downtube, I saw the many kinks and bends that are normal. But one bend seemed a bit strange to me. I pulled my other downtube out of the closet(the one I bought off ebay for the 6.2). It's the later model with the 2 bolt ball style flange on it. It's bends and kinks are minor compared to what I found on my 94. On the 94, next to the frame rail where the downtube passes by, it is kinked so bad that the airway has to be less than 1" tall. It just doesn't look right compared to the other tube or even just looking at it. I'm under speculation that something happened to it but may never know. But what I do know now is there is muscle in that engine begging me to let it out.

lupey6.5
08-24-2003, 13:05
my 94 downpipe looks the same. its almost like they creased it for framerail clearance but went wildly overboard. i've also heared that the bends were acctually to restrict power levels,*******s!

mhagie
08-24-2003, 19:21
HOOORAY Randy,you are on the verge of lucking out again,keep us informed when you do the exhaust upgrade. :D
P.S. what about the noise did it go away?

Turbo Al
08-25-2003, 01:25
My 93 downpipe looked the same too, and there really is not a GOOD reason for it. The BD replacement has NO horrific bends or flat spots on it and it fits just fine -- OK maybe a little harder (more work) to get at #6 & #8 glow plugs but WHO CARES.
Glad things are workin out for you Randee. Let us know when you get your first :D speeding ticket :D

Randee of the Redwoods
08-25-2003, 16:37
mhagie-can't really say on the noise. Yes, I started the truck and for some reason, maybe it's just cause I wanted it this way, but the noise didn't seem as loud as usual, and yes I was starting a cold motor(after sitting overnight). Maybe also because the exhaust was considerably louder due to the fact the cat was a bolts length away so there was a "whuppa whuppa" noise. Mostly, the engine seemed to be a freer spirit. Can't wait to chip it. Also wondering if excessive backpressure could be bearing on something internal causing the elevated volume level of "the noise".

jeffreydmet
08-26-2003, 14:10
Randee
I'm not a diesel expert but my truck has never quite performed like it seems one elses does either. A dealer sevice manager said to me that the CAT does ocasionally get plugged but this is rare. Really sounds like yours is plugged.

I did a similar experiment only I took my truck to a flat blacktop and timed it from 0-70mph at full throttle. Stock it averaged (3 runs) 22.8 seconds. With the Cat pipe disconnected it averaged 22.6s. Not a significant difference. I am not now sure that a larger pipe will help much. Maybe after I find what ever else may be wrong it will.

Randee of the Redwoods
08-26-2003, 16:56
My cat pipe is clamped on after the cat. Don't know if this is factory, but it is. I plan on ditching the after cat from that clamp back. If the cat checks out ok(nothing plugging it), I'll stick it back on and get a 90* bend from the Advance and bolt it on and have a shortened tailpipe setup until the replacement can be afforded. I'd like to keep the cat for now for noise purposes. Maybe the cat is plugged up after all. If it is, I guess I'll just chuck it and live with the open downpipe for a little while.
And I'm not too concerned with straight line performance, but the uphill performance difference with the open downtube has sold me.