Just got most of a Dynomax 4-inch exhaust installed on my '86. We adapted pieces from the Dynomax #19429 system, which is for the '85-87 trucks. It transitioned from the Banks turbo downpipe (3-inch) at the muffler (though we replaced the old, thin 3-inch from the t-case back with more 3-inch pieces from the kit). Couldn't go any farther forward without major fab work. Couldn't get much closer than about the transfer case anyway, no matter what. Barely enough room for a 3-inch pipe (plus the turbo outlet is 3-inch). We replaced a crimp-bent system that I had installed on the road when the original Banks stuff fell off after ONLY 18 years. (Darn cheap junk!)

Frankly, I wasn't expecting much,but I was pleasantly surprised. Spools up faster and boost jumped 3-4 PSI (to about 13) on hard accel. The butt dyno isn't indicating much change but the G-tech picked up about a 0.4 second on 0-60 with the truck loaded at nearly 7,000#. I'll try it again after I unload the 500 pounds of tractor weight I carry for winter. Looks like it might have dropped about 30-40 degrees of EGT too, but that's kinda hard to judge since it's so cold out now. Will also have it on a dyno in early April.

The Dynomax muffler is a straight thru but the truck is still quiet in the cab. It has a nice throaty rumble from outside the truck. It lost an annoying drone it had at 30 mph.

It went on easily with one glitch. The outlet was very low (about level with the hub), so the hanger on the over-axle pipe was shortened by about 3 inches to bring it up.

 

That's the same problem I had. I don't know why they make those hangers so freakin' long.

 

This is what I was afraid of. I guess my 3" strait pipe is a little too small, oh well, I never go past 2500 anyway. I guess once you put the new sidwinder setup in you should be able to keep up with the newer rigs afterall .

 

David 85: I should probably clarify that I was replacing a really crappy, hackmesiter "Custom" crimp-bent system, not the original Banks Mandrill setup. I truly believe (and should shortly be able to prove via a simple formula) that, for our trucks, 3-inch mandrill is all they can use. Mufflers are another matter. Certain mufflers may be restrictive enough to be a problem (the muffler is always the most likely restriction). The nice part is that on a turbo diesel, a too-large system doesn't hurt low end power as it would a NA truck, but too large could hurt your wallet. So, bottom line, I don't think this new 4-inch setup would outperform the original Banks system. I hedge a little because I haven't seen flow data on the humungous Banks muffler they used to offer.

No plans to upgrade to a Sidewinder, though that would be fun.

 

Well Mine is mandrel bent throughout (Tig wielded elbows and strait pipes the old fashioned way), but I will probably add a muffler some day, I'm afraid to engine brake for getting complaints. You can't hear it in the cab, but if I roll down the passenger window (power windows), the crackle echoes off obstacles on the side of the road and I would imagine its quite annoying to some one on the street.

Campbell river isn't the small logging/mining town it used to be, and with all the high end subdivisions I'm afraid of pissing some one off. For now I just keep my boot out of it unless I'm on the freeway (which isn'y such a bad idea anyway).

BTW, do you have stock head bolts in that engine?

 

David85: Stock head bolts. I put head gaskets on it about 12 years ago. You know, that weepy external coolant leak they all had, but mine didn't do it early enough to get the new head gaskets under warranty as many did (including some people I knew). Otherwise, I've done to that engine is a rear main seal, rebuilt the injection pump and replaced the injectors at 90K miles about 10 years ago. It was mostly the pump, it suddenly really lost power, though I can't remember exactly what the problem was with the pump. The injectors weren't bad, so much... but, you know. Replaced the original glow plugs 2 years ago. Still running the original glow plug controller and starter. Replace the original water pump 8 years ago. It still uses the same amount of oil it did from day one.

 

Not sure of the history on my truck, I got it when it had 334 000 Ks on the clock, but it was the only one that didn't have a manual glow plug system and the PO knew his way around the truck (more than could be said about all the other sellers that I met before this one). He was very sorry to see it go, but his newer powerstroke had overdrive, and wasn't as bashed up. Even gave it a sentimental pat on the hood when I drove it out of his driveway.

I'm not sure if FelPro head gaskets were used from factory, but if not than at the very least the heads have been off before I rebuilt the engine. The fuel system is not original, and I may be in for a new IP. I did find the fire ring was slowly separating from the gasket on two cylinders when I finally tore into it. I maxed out at 16 psi once, and later backed off on the fuel, chances are thats when I went too far and weakened the head gaskets. Just curious if you had any such problems, but it would seem not.

 

David 85,
Enjoy your posts, no over-inflated B.S. Straight questions, straight answers and legible.