Glad to see your getting somewhere man. Good luck and def keep us posted!!

 

never got into modding the 8.3 we had in the kenworth tandem truck we had ,it was rated at 275 hp and seemed to work well,this engine is basically the same design as an IH dt466,around 500,000 km we had the head gasket go and a broken head bolt ,I swapped it in the shop at home ,they are an easy engine to work on

 

You mention your egt's are around 8-900, is that pre or post turbo? If it's pre and your gauge is working right, you probably have a lot of room for power improvement without much risk. If that's post, you're still ok but don't have nearly as much headroom.

 

v8440 we went pre-turbo, right in near the 5th & 6th cylinders on the manifold. Unless forced to, I don't see why anyone would go post-turbo. Attached is a pict when we were hooking it up. At the top you can see where we tapped into a existing port on the PacBrake for backpressure and under it on the manifold where we drilled and installed the fitting before hooking up the thermocouple for the pyrometer temps.

The 2nd pict is where we used another existing OE port (one of several to choose from) to get our boost from. We had to use a adapter to reduce down to the proper size for the Isspro gauge pickup.

With a #6 BD plate in there i think we need to slide it if we go for more power (which will wait until summer and some higher ambient temps). To me, it just feels like it's not making the boost/power it should be if it was full tilt now. With the plate their site says it takes a 250HP to 375. I'm just not buying it as it's installed here by the previous owner. I'm thinking it's set really conservative as it is now.

 

That sure looks like the thermocouple is post turbo. Pre exhaust brake, though.

 

It looks pre-turbo to me. Look at the silver fitting in the exhaust manifold, not the copper fitting in the down pipe.

 

Assuming the thermocouple is screwed into the silver fitting down on the manifold, then yes, that's preturbo. I've always put them in the manifold right before it enters the turbo so that it'll get heat from at least 1/2 of the cylinders, but I can't imagine that your location would cause the readings to differ that much from what I described would read. If your silver fitting is for the probe, then I'll say that your lack of power is due to not near enough fuel for the power you want. If that's the case, slide the plate forward.

 

I know this is an old thread but I am looking into building a Dodge D600 hauler with a 8.3 in it and a 13 speed behind it. basically a really big flat bed Dodge. Curious how it came out int the RV. Any idea how much HP you got and where you were getting at EGT wise and MPG

Jeff

 

Sorry been out of it for awhile.... Here's the latest...

We did advance the timing, +2.5 degrees to to 14.5, just a little, not too much. With that and previously straight piping the exhaust so it breaths and builds boost quicker. Next step was to incresae fuel and build more boost but for 8 months it's been down and I don't see whats going on with the MD3060 transmission. Before that it ran STRONG, like we shed 25% of the weight. The Gov Spring mod worked wonders for the shifting of the tranny. Before it felt like it fell over flat then shifted, now it feels like a V8 Chevy/Turbo 350 that had a shift kit put in the tranny.

Saw the prev replys with question about the egt temps and we are getting it between the 2 leanest cylinders 5 & 6 as I understand it. That should be where it runs the hottest as any excess fuel is not acting to keep the cylinder cool. Or thats how I understand it as it was explained to me. We had TWO hiccups where a repair made by Southern Plains less than 2K before failed. First one was a damn cr@ppy crimp connector on fuel cutoff solenoid let the wire come straight out, fixed it, in place, on the side of I-10 in North San Antonio. Next trip my mom call from Beaumont where her and my sister were and it wouldn't shut off. My Uncle was local and he found the entire solenoid dangling, all the bolts were gone, they'd vibrated out. @$(^%#$%(* Moral.... Stay away, very far away, from Southern Plains in Tucson, AZ.

At this point we are getting a code for a speed sensor, which I replaced, but I think the problem is in the touchpad as its still doing it. While in D it'll beep and drops into neutral and sometimes goes dark all on its own. Restarting after turning the ignition all the way off resets it but it'll reoccur constantly and you have to keeping restarting to limp it off the road.

and I can't find a local person to work on it. RV companys say its a trans issues, they don't do that, and trucking companys don't work on RV's, we're just stuck between a rock and a hard place. At this point the parts I'd throw at it get really PRICEY (shifter touchpad/trans ecm...).

My Mom did get a couple of trips in before it cropped up but no really long ones. Don't know if it affected the mileage any. I doubt it would. Advancing the timing should actually improve mileage as you get a better hit, at the longevity of the engine (harder on the pistons, rods), but this coach will fall to pieces long before it'd hit the 500K+ mark where we'd have to start considering the hp mods as even a small factor.

If anyone in the San Marcos area knows about the Allison MD3060, works on them, I could use and would appreciate a referral.

 

Just a update: It's been fixed for quite awhile. Been back and forth to Wisconsin the last couple years.

It WAS the Allison ECU. Diagnosed accurately by Rush Truck Center in San Marcos. Price on new one was eye-wateringly expensive. We found a fix online (RV Shifters aka Transmission Instruments), mailed it off and they resoldered, retested, etc.. did all the magic on it and it's been shifting perfectly ever since. Cost was just under $600 plus the tow and Rush's 1hr diag fee (which was essentially confirming what I thought it was).