12 Valve Conversion Help & Tips???
 

Hey guys. I'm doing a Cummins swap into my 1980 Powerwagon that has 12" of lift on it with 40" Boggers. The entire suspension and diffs are built with Yukon Chrome moly shafts, CTM u-joints and Detroit lockers. My old 360 is way too tired and I'm putting in a good ol' 89 Cummins. The only problem is that I have NO experience with the first gen 12 valves. I am used to the VP trucks and the CR trucks. Can someone point me in the right direction with power upgrades??? Will I be OK with the truck not being intercooled for offroading. That's all this truck does is offroad through huge mudbogs, through the bush and so on. Tater, got any tips????

Thanks for any tips or suggestions guys....:cool::cool:

what kind of power do want ?????????? do u want fuel mileage ?????? do u want smoke ??????????? ... i have been playing with these trucks for a few years ,,, they turn on very esay and fairly cheap.... and is it auto or standard ??????????????????????????....

the things i would start with

hx 35
3000rpm spring
unhock the afc
lift pump up grade
fuel screw 1/2 turn off runaway
big exhaust like 5 inch
make sure u are getting full thro

Purely offroad. Want good bottom end and it's an automatic that was just rebuilt. Thanks man...:cool:

dont get crazy fuel without an intercooler.

Yup also with an 89 engine, EGT's are a concern not only due to lack of intercooler but due to cracking the head. The 89-91.5 engines utilize 9mm injector nozzles and the material between the exhaust valve and injector port is quite small. You keep the fuel in check and it should be OK.

In my 89 I had the 180 Hp injectors, stock turbo and 3.5" exhaust (pillaged from a Bank$ Ford pipe setup as 4" wasn't available then). With just those injectors, tweaking the throttle linkage (instead of the governor spring) and not touching the fuel screw was about the limit. My 93 I went without the injectors and just maxed out the pump and got a Dyno of 268RWHP with it.

If I can muster some time, I would love to stop by for a peek.

I uploaded some photos of my old rides to my gallery..:cool:

i no a guy running 350 hp nonic ... but a cooler is a good idea but not a most . the 1st gen can run hot then other cummins say 1200-1350 all day long .new ones 1100.. the big exhaust helps alot , my egt went down almost 400 when i put it on

That's sounds great J..

Too big of an exhaust, won't that cause bottom end loss??

leave the down pipe 3".. thats what i did. and i gained power ,,,

the answer to that is no.



anything after the turbocharger is as low of backpressure as possible. cummins only list a maximum spec for BP in the exhaust, on the big QSKs anyways, and its VERY little allowed. so no, you can't have too big of an exhaust. thats naturally aspirated gasspot talk going through your head. shake it out [laugh]

AND there is the answer thought is what i thought but i was not sure so i left for some that no's like luke

that being said, it has been proven over and over, that in reality anything bigger than 4 " is just for show,, that is all that is on my truck is a 4"

Kevin

isn't 5 inch a benificial after 600hp?

Good one Luke..[laugh][laugh]

That should be a sweet rig. I love the old body style....I have an '80 W200 sitting outside the house right now that I use for a knockaround/yard truck. 440/NP435-could use a 205 swap in place of the 208 that's in it now but that's a project for another time. This summer I was trying to find a Crew Cab long box to swap a CTD into-but I kinda let that one slip to the backburner for now. Went on a parts-truck acquiring spree in anticipation of it though-there are 3 '80s and a '77 sitting waiting to donate....

I would think a swap to a wastegated turbo ala HX35 should help the bottom end a ton by getting the boost/fuel going quicker. I'm with the others about keeping the fuel in check without an aftercooler though. Maybe a good time to add one? Thought I read somewhere about a PSD aftercooler being used as a 1st gen upgrade. Should be able to find one of them kicking around from a dead one-god knows there's lots matching that description. :cool:

Jason

Personally I think it is not. Just to keep one thing in mind, the turbo outlet is only 4" not 5, so it is going to bottle neck right there. I have never once heard concrete proof that a 5" exhaust will increas HP. Trust me if I thought it would, it would be on my truck!

Kevin

Jason, I just by chance have my old HX 35 kicking around from my 2001.:cool::cool:
I know where there are a few busted up ol' Fords. Maybe I'll get lucky and find an intercooler???
HERE'S MY RED NECK BUSH KILLER!!! MY GOAL WAS AS REDNECK AS I COULD MAKE IT, AND YES, IT HAS DIXIE AIR HORNS ON IT!![laugh][laugh]

when i went from 4 to 5 inch i loss almost 400 ,,, so how is it not hopefully ??? just wondering not be a *** , just wondering

I heard the same ...to big and bottle end drops off..I don't know...[duhhh]

Thats just not true though. With out a doubt everything after the turbo is moot, as long as it isn't restrictive.

really you could have 12" of pipe at the turbo outlet and that would be sufficient, if it wasn't illegal to have the exhaust exit before the passenger compartment.

no, I saw it proven mathmatically once. the volumetric output of the 5.9 at rated speed and load, is less than the max flow rate for a 4" id tube. if you follow what I'm saying. the 6B cummins can only make so much air output. which a 4" tube can easily handle.

EGTs won't drop drastically if you go to say 7" pipe..........EGTs are a reflection of the internal temperature of combustion right. So... you have to take fuel out or put more air in to lower egts, or water/meth to control egt...but that raises cylinder pressures. its a big slippery slope........[laugh]

Jamie, you gonna put in air bags in the front? Or just put in heavier leafs? I wanted to do a older power wagon, the older wagons have a nice look to them. You changing the axles in the front and back? They might be another weak spot, so you might not want to crank up to much power. Being a 360 truck you're probably running 9 1/4in diff. I would try to find larger axles from a newer diesel truck. dana 60 up front and throw in a dana 80's in the back. Being a mud truck run 4in stacks, so nothing will get hung up. Most of the exhaust stuff is ready available and you could build a system on the cheap. I ripped off a few exhaust systems on a few logs, so it doesn't hurt as much when in only a few dollars. Nice truck

the theory of 5 inch exhuast being worse than 4 inch is that your not putting out enought exhuast to fill the pipe so it creates back pulses which slow the flow and turbine wheel down. Now once you run past 600 hp you put out enough flow to fill that pipe and it is benificial. This isn't my theory and i can't remember who told it to me to give them credit.
Personaly a 4 inch down pipe that tapers into a 5 inch gradualy would probable be the best. seams like when they try to put a bigger pipe on exhuast systems they just crimp a big pipe down to a smaller pipe to make it bolt to the turbo. not very smooth for exhuast flow i think.

Jamie, I LOVE THAT TRUCK!!! [laugh] Pretty sure it has a 60 up front looking at the pics of the front hubs. Imagine it's a 60 in the back too-maybe a 70?

Dad had a number of this body style when I was a kid as work trucks....and I drove a '76 D100 for quite a while as a young punk. Every time I see one, it brings back a ton of good memories. Guess that's why I went on the parts-truck buying mission. One of the '80's that I picked up was a D150-360/727...air/tilt/cruise/power windows (1st year for that)/power locks/sunroof/leather seat(AFAIK only year for that)/AM-FM-cassette/turbine wheels (1st year for them) in black and silver. I would have killed to have had that truck when I graduated in '86 (dating myself now....)-but by the time I got to it, the rust monster had pretty much killed it. I did take it for a rip a time or two around the gravel before I parked it and thought about what could have been!

hey the 9 1/4 and dana 44 is a strong set of diffs , i ran a 450hp 383 in my truck and i have never had a problem with them other things yes lol but not the diffs ,,, here is a few pics of my truck

Its not the hp to worry about its all that extra torque that you'll have. Mix in the sloppy guey mud and big wheels. You could have issues, Jamie will just baby the ride anyways and it will be show shape. I would also put more skid plates on it. I tend to break stuff. I wish I had more space here so I could have more toys. I would just find a crate 360 engine. Its so much lighter than the 5.9L and you'll wont be using the front bumper to dig out local mud pits.

hey mike ,,,,, my 383 450 hp at 4000rpm 473 ftp at 3500 and the weight of it is 25 pounds less then a stock small block .and it likes 5000rpm it has been there alot lol... just one thing THERE IS NO SUB FOR CUBES :).. and it is fun as hell to walk all over people in a big old muddy truck . and if jamie is going to ran boggers he will need better axles . boggers are like having 50 shovels on every corner lol ... i have had twosets of them . i like the tsl's myself drive nicer ,,, but that is my two cents

This "theory" has been dyno proven. Going to a 5" setup has no benefit and is actually a detriment to flow in the pipe. Its not so much the pulses, but you want lamilar flow, that being all the fluid is flowing in one direction in a straight line (the main reason we use mandrel bent pipes). The large pipe causes turbulence, especially at low flow ie. low rpm and then artifically causes "backpressure" or loss in the system. If you can get lamilar flow in the piping with little pressure loss, you actually get a scavenging effect and the flow increases in efficiency.

Most guys in the 600 club have compounds where the primary is a 5" outlet anyway.

Jamie, when you have the engine in your hands, call me. :)

If you have the money, go with a 392 hemi. Light weight and tons of HP for sling mud. Rev's out good. An RB motor done with parts to 500in and aluminum heads, would be another good ticket. Tons of different combo available. A diesel engine would work nice to, heavy though. Even a good rebuildable engine is the same money as crate engine from summit or jegs.

If it was my ride, I would do it on the cheap. Do a re-ring and hone, find some rebuilt heads. A spray engine can overhaul. Find a carb that works or do a quicky rebuild on the old carb. Find more mud, no need to dump in tons cash.

Thanks man. I have had it for 16 years now. It's a 60 in the front and rear. the front is full chrome moly and the diff has been rotated. I've spent way too much money on it and I got this 12 valve and auto tranny for basically free...

I will Jason.:D

Nice catch on the diesel, you have way more spare parts than me. You gonna add some extra springs to the front. You'll have to bring it to one of our mets, so the rest of us can drool on it.

so how exactly are these being dyno proven? what kind of scientific method is being used> I understand fully the technical aspect of what you're saying, but i don't believe it. that pipe diameter increase of 1 or 2 inches produces a measureable loss of low end performance.

The ol' girl is beat up good but still has many miles to go..
You won't drool over it, It's a heap but a fun heap of.....[laugh][laugh]

Those are the best kinda of toys. Don't worry I'll wipe off the finger prints. It you get a 5.9L under the hood and actually use it to bash in the bush with, I be interested.

I have five inch exhaust on my 5.9 and i dont have an issue. my pretty plain truck turned almost 500hp on the dyno with no much put into her, and loosing power to the 37 inch rubber and 6 inch lift. so you may all have your theories, but my truck had it on when i bought it, it has unique sound that no one else has in town, and when i leave you all in my black smoke thats all that matters to me!! because in the end its gonna be a girl in a sweet cummins diesel thats going to kick all your butts anyways!!!! lol later!

cheap motor that works nails
 

cheap way to build a cheap motor that puts out 300hp .... get a 360 magnum and put a carb with a carb intake on it ,,, under 600 u can have a mint motor ... if u want cheap motor for a mud truck

I ran a set of PDR 40/3B with no exhaust. That set-up spooled pretty fast without the exhaust. Once I added the exhaust, it slowed down some. I think I scared my neighbor hood with it though anything. I just finished putting on the twins and had no exhaust ready. You have to try stuff. I have even tried running my 300C srt without the exhaust on it. Now thats one noisy car.

I remember a few years ago there was a writeup in the TDR WRT to the 5" vs 4" for spool up and overall performance. The test had two similarly performing trucks with stock turbo chargers. The main difference was found in the low end spool time not being as great for the 5" system. Expecially at the time where a 5" kit was probably 25% greater cost or more. Just exhausting the turbo to atmosphere is not as efficient, even though the turbo is a pressure drop type device. Having the momentum of the fluid is just as important as having low pressure.

Mike, you are the turbine expert... Am I not interpreting the results correctly?

I thought that it ran better with the open exhaust, of course I just put on twins on. I didn't not dyno the truck at that time. I'm with Luke, backpressure is not you're friend. Honestly it would be hard pressed to see any difference between 4in vs 5in. I just think that 5in stacks look cooler. Which pump you running Jamie and what year is the motor? You running a VE pump on that thing? We just gonna have to dyno tune that sweet ride up at our next dyno outting. I just want time off so I can have time to pull wrenchs, my hemi is starting to look good to me. I want to start driving the old ride again. I miss the shaking and the rattle beast.