swap to a 12V or stick with the 24V?

whitneyj

whitneyj

still in pieces
Joined
Jan 31, 2012
Messages
822
Kind of a lame question, but I've been tossing it around long enough without coming to a desicion...

Truck is in my signature, after running the VIN, then entire engine is a 24V, not just the head.

I thought I was losing compression between cylinders due to what I thought was a bad fire ring, but it ends up I just have a worn out engine. I figure an entire engine rebuild will run me $10K between the parts and machining-this includes milling the intake off and building an intake, I'll be doing the P&P. I don't can't have this truck down for that long, so my thought process lead me to build another engine over the course of a couple months and swap the engines over a weekend.

I was thinking of switching to a 12V as I can find 12V's all day long, they have tons of aftermarket support and documentation, and have been around a lot longer than the 24V.

The only reason I'm thinking of staying 24V is the head flows more CFM potentially from what I've read.

The truck is used soley for towing, but once the new motor happens, a solid break-in period, and the comounds get redone I'd like to try my hand at pulling.

So which motor should I use? Money isn't a huge limiting factor, but it is a concern. $10K is my max budget for the motor.
 
Why would it cost 10k for a rebuild? I just rebuilt mine with new cummins rings and bearings and maybe had 1k in all that stuff plus gaskets and other replacement parts. I had my head decked, o-ringed and a valve job done as well as the block decked and honed and had maybe 1300 in machine work. Re-used the pistons as i saw no reason to buy new.

I would just rebuild what you have...
 
I'm not expert but I think a 12v head flows more, hence the reason all big high hp drag & pull trucks are still 12v rather then p-24's
 
TRUBBS said:
I'm not expert but I think a 12v head flows more, hence the reason all big high hp drag & pull trucks are still 12v rather then p-24's
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a stock 24v head flows more than a stock 12v head. the 12v has better valve train stability, better for high rpm's.
 
jlbayes said:
a stock 24v head flows more than a stock 12v head. the 12v has better valve train stability, better for high rpm's.
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That's what I had read as well.

The truck will rarely see 4K rpm, but I regularly shift at 3K at keep the NV4500 alive with heavy loads.

So far it sounds like 12V has more pro's.
 
I have a p-pumped 24v right now and Im going to a 12v if that tells you anything. For 10k you can have a fully fully fully built engine either way.
 
What were you doing that adds up to 10k? How many miles are on it? What makes you think its worn out?

I'd stay 24v if you're dd'ing it and keeping the rpm's low and it won't cost any more to rebuild the 24v than a 12v.

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mathews8pt said:
Why would it cost 10k for a rebuild? I just rebuilt mine with new cummins rings and bearings and maybe had 1k in all that stuff plus gaskets and other replacement parts. I had my head decked, o-ringed and a valve job done as well as the block decked and honed and had maybe 1300 in machine work. Re-used the pistons as i saw no reason to buy new.

I would just rebuild what you have...
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Primary reason being I'm not doing a stock rebuild. It's nothing to fancy, but it's going to make ~500 hp and I don't want to have to open this thing back up under 200K miles.

Off the top of my head my build will be something to the effect of-Hamilton valvetrain to include cam, shot peaned/polished/balanced rods, machined/balanced pistons, rotating assembly balanced to 5K, I'm polishing the entire underside of the block, 3/4" girdle tied into all mains and block, O-rings (current 24V head has fire rings and with all the bad rap they get I want them gone for peace of mind's sake), port/polish the head as much as makes sense with reliability still in mind, 5 angle valve job, intake milled off, building own intake, and that's about all I can think of right now.

Anything sound to off?
 
You're getting lot more serious than I'd worry about for 500 HP but its your money. Its going to be pretty much the same $ either way.

Why do you think the 24v is sick?

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chevota84 said:
What were you doing that adds up to 10k? How many miles are on it? What makes you think its worn out?

I'd stay 24v if you're dd'ing it and keeping the rpm's low and it won't cost any more to rebuild the 24v than a 12v.

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I don't remember the pricing on everything, but the cost of machining was close to $3K locally, plus the cost of parts, ect.

Motor has 264K miles on it

Compression test was done and they're on the low side of spec or just below. Still runs strong, but at full boost (pegs a 60 psi gauge) I lose oil out the breathers-which is very possibly helped from a bad seal on the secondary turbo.
 
chevota84 said:
You're getting lot more serious than I'd worry about for 500 HP but its your money. Its going to be pretty much the same $ either way.

Why do you think the 24v is sick?

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Click to expand...

What's going to far? The girdle is the one thing I really second guess as being needed.

Biggest thing is when I'm driving from WI to CA or NC I can't afford to have something major go down with a 32' gooseneck and 2 jeeps/trucks on the back. I want as much power and I can use as reliable as possible. If I have to spend an extra couple grand, then I feel it's worth it. But if I'm looking at things that are used for the 1000 hp territory, then I'd better re-think those parts....
 
Damn man, i had a 700hp goal(which im really close to now) and my list is a LOT shorter then yours. Stock bottom end in mine still. Opened up the PTW clearance to help with scuffing problems and 0-ringed my head. Im still running stock head bolts as well. valvesprings and a cam, along with a ported head that i did myself. I wouldnt be afraid to drive mine accross the country if the need arose. IMHO i think you are going WAY overkill for what you want, but its not my money and if that helps you keep from worrying about it then that sounds like a hell of an engine build for 500hp.
 
whitneyj said:
Primary reason being I'm not doing a stock rebuild. It's nothing to fancy, but it's going to make ~500 hp and I don't want to have to open this thing back up under 200K miles.

Off the top of my head my build will be something to the effect of-Hamilton valvetrain to include cam, shot peaned/polished/balanced rods, machined/balanced pistons, rotating assembly balanced to 5K, I'm polishing the entire underside of the block, 3/4" girdle tied into all mains and block, O-rings (current 24V head has fire rings and with all the bad rap they get I want them gone for peace of mind's sake), port/polish the head as much as makes sense with reliability still in mind, 5 angle valve job, intake milled off, building own intake, and that's about all I can think of right now.

Anything sound to off?
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I would put new bearings, rings, rob bolts, main studs, head studs, cam and a fluidampner and call it a day. Plus springs and push rods for the top end. But like the other guy said its your money.....:bang
 
kleann said:
I would put new bearings, rings, rob bolts, main studs, head studs, cam and a fluidampner and call it a day. Plus springs and push rods for the top end. But like the other guy said its your money.....:bang
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So the total rebuild doesn't sound to be to popular or needed....

The biggest thing then if I keep the 24V are the fire rings. These rings have been in for 50K miles, never retorqued, and apparently aren't cracked. I just don't want to mess with doing a basic rebuild with decking the head and block, installing new fire rings, then those suckers pop on me 5K down the road 1100 miles from home....

If the fire rings can be made as reliable as an oringed head, I'll put serious consideration into just a rebuild of what I have now.
 
well the emissions and OBD stuff is different. And your state may implement emissions laws in the future that make it hard to comply. If you dont care Id say go for the 12 valve swap.
but that depends on how it fits what you do.
I like not having any EPA mandated bullchit on my engine. It can run on near anything that burns and you could probably drop an EMP on it and it would still run.
Just flipping off the EPA is enough for me though.
 
I don't have any emissions anything on this 24 valve. It's had a P-pump conversion done to it. I've run waste oil in it when I didn't have anything else.
 
What spec did you use for compression? The s.o. 24v is the lowest factory dodge Cummins.

Like I said, its your money and if balancing and shot peening makes you feel more comfortable then go for it. I'm kind of a cheapskate though and these engines have proven themselves to live just fine at 500 HP with stock parts so I personally wouldn't go that far.

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I honestly couldn't tell you what was used, I was the one turning the motor over and pretty much following direction. I'm big into metal fabrication and anything drivetrain related, but I've always been shy with motor work as there's to many things with tight tolerances that all need to play well together. I always have my diesel technician buddies lend a hand. It's not that I can't do it, I just don't feel comfortable doing it myself.

With everything I've read 500 hp is pretty conservative with what these motors will make with primarily stock parts. I am looking to have a little fun and this truck was bought for towing purposes only-unless the dd goes down, so I want a solid motor that'll take near anything thrown at it for as long as there's fuel in the tank. There's a build on cumminsforum.com that was kind of the inspiration behind wanting to go farther than the norm. Here's an example-if I'm pulling the big trailer with a solid load on it and I want to blow the doors off something going up a mountain passhavering want to have to worry about shifting at 5K, at full boost-60+ psi-with keeping the ETG's 1200* or less.

That's stupid case scenario, but it gives an idea of the peace of mind from the power train I'm looking for.
 
I bet you have a 53 block. Your parts list is way overkill for what you need. I would stay with a 24v head. It flows more air than a 12v will ever do. Somethings on your parts list you don't really need. If i was building it i would go about it a different way.
I can tell from your lack of experience you don't really know what you need.

Don't take that the wrong way, i would spend my money on whats really needed. And not on stuff thats not needed.
 
Diehard Ram said:
I bet you have a 53 block. Your parts list is way overkill for what you need. I would stay with a 24v head. It flows more air than a 12v will ever do. Somethings on your parts list you don't really need. If i was building it i would go about it a different way.
I can tell from your lack of experience you don't really know what you need.

Don't take that the wrong way, i would spend my money on whats really needed. And not on stuff thats not needed.
Click to expand...

Why would you think its a 53?

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