Thoughts on Performance upgrades/direction/Cummins?

drewr13NJ

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Hi everyone. Been lurking here for a couple years and posting occasionally, hopefully adding to the conversation. I have a dilemma and I wanted some opinions/thoughts. I'm thinking of doing a Cummins conversion on my 1992 in my signature. After doing research, looks like I'm going to be into it at least 5 grand, probably more when all said and done depending on how much I buy/fabricate, and Ill probably have a 12 valve Cummins with probably 200k plus mi in my truck. My truck has 109k mi on it with a rebuilt, sleeved, 7.3 NA in it now. I have a turbo kit sitting in my garage waiting for installation. I have 3 sets of pumps and injectors for the 7.3 IDI, and a spare turbo block in my garage. The truck's body has some work that needs to be done, but pretty solid truck overall. My question is, should I just turbo it, possibly get a bigger pump, intercool, stud etc,(probably $3 grand depending how far I go) and be happy with those performance mods or does anyone think the Cummins just blows the IDI's away in every aspect? I'm not a speed demon by any means, but I feel 250hp/500lbft torque would make it an enjoyable truck to drive, which is what I was planning on doing with a Cummins conversion anyway. No plans on towing, but thinking if I did, 10 to 12k would be max. I know the torque and power numbers in the specs are similar stock. Never drove a Cummins, so I'm not sure about power delivery/driving experience. I know the thought of putting the Cummins in a different drivetrain is cool, but its hard for me to swallow 5 to 10 grand just for a different engine, plus all the time needed to do conversion. Oh, how would the Cummins handle WMO vs 7.3 IDI? I am using quite a bit of WMO with fuel prices being so high. Any thoughts? Thanks for the input!

PS. Moderator: please post this in the diesel conversion forum if you feel it is better suited there.
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Isaac Ristow

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250hp is easy with a idi and the cummins will rattle your teeth out and be loud and obnoxious in the cab never been a huge fan of them. I put a t6.354.4 perkins in my chev 1 ton simply because its not your every day cummins swap and the perkins runs so so much quieter and smoother than cummins
 

franklin2

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If you are running WMO, I would run what you have till it wears the pump out, and then decide what to do. I like the cummins swap if you are going to use it, but if you are not even towing and just running junk fuel, why not just keep putting injection pumps on what you have?
 

Nero

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12v is overrated, says the Cummins mechanic. Go big or go home, get a common rail 6.7 :cool:
 

franklin2

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12v is overrated, says the Cummins mechanic. Go big or go home, get a common rail 6.7 :cool:
They say there is an engine in the engine compartment of those 6.7 trucks. I have to believe them since it does run down the road. But lift the hood and look for it, you can't find it no matter how much time you spend looking. What a mess.
 

Nero

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They aren't too bad, but mostly what I work on is semi trucks. A lot more room in there. Unless it's a car hauler or a Volvo chassis.
 

snicklas

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My opinion, you own the turbo already. Put it on and turn up the pump that’s on there (follow the guidelines so supporting accessories, like a pyro) and see what you think. If you want more, a pump and injectors will still be less than a Cummins swap.

Dont get me wrong, I know what a P-Pump 12 valve is capable of… I got to play with Travis’s nanny goat (search on argve on here) I also saw what his Enterprise would do….

Less work with similar results just perking up the IDI……
 

u2slow

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I give the nod to the idi for burning wmo. Do that to save money while you get the Cummins stuff ready, or get the whole dodge with one.

I do not miss glow plugs, dual batts, 2 cylinder heads/gaskets, and less room to work. It's not always about making power.
 

Nero

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But now you get to deal with grid heater, P pump or vp44, and frankly I'm surprised it starts on one battery. It's all about what hurdles you want to deal with. Each has their pros and cons.
 

u2slow

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Mechanical 6BTs are VE or P pump for road applications. Either will make 250hp. I actually find the VE nicer for a daily driver.

Edit: one battery is stock on a 89-93 dodge, and the grid heater isn't needed until theres frost on the ground.
 
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drewr13NJ

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Thanks for the replies. I was looking at VE pumped 12 valves for about $2 grand, but they seem to be bought up quick. That is also my understanding that 250hp is very doable with those rotary pumps. Typically the P-pump used engines are $3K up. I think Ill just use the 7.3 IDI, add the turbo, turn it up a bit and see how I like it. I do have a Hypermax pyro and boost gauge too. Ive heard the Bosch pumps are quite expensive to rebuild too.
 

u2slow

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May as well run the idi until it gives you significant trouble, and burn down that wmo supply.

6BTs can be had cheaper if you can wait, and willing to take a whole truck. You want to buy any cummins with an overdrive transmission (and tcase if 4wd) unless you're rich enough for a custom adapter.
 

Nero

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They can be, especially since they're bigger. I have an rv I'm working on at work, thing is an absolute pile. Missing body panels, cracked glass... Ect.... But it has a 6bt with a p pump, and they swear on rebuilding it. Has low compression. Just to have the p pump rebuilt was $1800, and that's by a local injection shop.
 

u2slow

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Bosch injection pumps are worth every penny. They're very tunable, intended for 5.9-8.3L displacement, and also are designed with boost-reference for turbocharging.

Price a new one and see how a rebuild compares.
 

Nero

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I agree a Cummins is worth every penny, but that's just it... It can lead to a huge up front cost, and to me I don't have or want to drop that kind of cash on a swap.
 

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