12 valve motor w/ 24valve head

[diesel junkie02]

i was thinking about putting a 24 valve head on my future 12 valve race truck. does it just bolt on or do i have to do a little modificating?

[stuckey_272002]

you will have to change the pistons.

[DieselPower359]

yup, 24V head = 24V pistons 12V head = 12V pistons

[JamieWood]

I almost have this exact build completed. I have found out the hard way ($) that you will also need the 24v push rods and the 24v cam. The rocker ratios between the 12v and the 24v are different. If you leave the 12v cam in you will loose some lift. (possibly below stock)

[diesel junkie02]

damn i always thought they were the same thing. if you put a 24v cam in a 12v motor/12v valve train would it give more lift?

[JamieWood]

Originally Posted by diesel junkie02

damn i always thought they were the same thing. if you put a 24v cam in a 12v motor/12v valve train would it give more lift?

On that I'm not 100% sure. Hell, really I'm not even 100% sure about the 24v. I'm just going off of what the guys a EEP told me. Maybe we can get some cam guru to chime in on this subject.

[2000wvdodge]

i think it would be too much, if you cant afford the 400-600 dollar cam, its not worth taking the chance on installing the wrong thing, then having larger problems.

[SHughes]

Originally Posted by DieselPower359

yup, 24V head = 24V pistons 12V head = 12V pistons

The pistons really need to be matched to the injectors right??

What I mean is, with a 24v head you are running 24v injectors - requiring the 24v pistons. The spray pattern from the injectors needs to be matched to the piston bowls. Right??

And what about head studs? What is the difference between 12v and 24v? Which studs would one use??

[2000wvdodge]

you can only use the 12v set on a 12v and a 24v set on a 24v. none of the studs match in length between the two sets, if that is what you are asking, you have me a bit confused.

[JamieWood]

I used also used a 24V HG. If it matters. The only thing different is a couple of the steam holes are smaller on the 24V HG.

[SHughes]

Originally Posted by 2000wvdodge

you can only use the 12v set on a 12v and a 24v set on a 24v. none of the studs match in length between the two sets, if that is what you are asking, you have me a bit confused.

Stud length is what i was thinking would be different, I assume everything else about the studs is the same, all 12mm between the 12v and 24v, witht eh esame thread pitch. Length is the only difference??

[Vefreak]

So wait wait wait wait wait. You guys are telling me you can put a 24 valve head on a 12 valve block. As long as i use the 24v pistons push rods and cams? I'm kinda new to this whole swap and match thing between the 12v and 24v, so if someone would fill me in on some things i should know, that would be awesome.

EDIT: of course i would have to use injectors with 24v spray angle too.

[SHughes]

I don't think any of us in this thread could be considered and expert. But yeah, that's how I see it.

Now if you really want to get confusing...I plan on running a Common Rail head with 24v injectors on a 12v short block. I think some custom parts are going to be needed.

[Vefreak]

Could i have my 12 pistons fly cut for the valves? and would i have to use new custom injector lines? can 12 valve injectors screw into a 24 valve head? Because using the stock injector line, my mechanical pump, 12v injectors and having the pistons fly cut would be the best route for me. That is of course i travel down this road some day for my devious plan.

[blkout]

I ran a 12 valve block and 24 valve head all season. You will have to have a different cam ,pushrods, pistons,and injectors for a 24 valve

[2000wvdodge]

Originally Posted by SHughes

Stud length is what i was thinking would be different, I assume everything else about the studs is the same, all 12mm between the 12v and 24v, witht eh esame thread pitch. Length is the only difference??

correct, everything is the same except length.

[rs359]

Originally Posted by Vefreak

Could i have my 12 pistons fly cut for the valves? and would i have to use new custom injector lines? can 12 valve injectors screw into a 24 valve head? Because using the stock injector line, my mechanical pump, 12v injectors and having the pistons fly cut would be the best route for me. That is of course i travel down this road some day for my devious plan.

The 12v pistons have the bowl offset the 24v pistons have the bowl in the center which means the pistons must be changed. The reason for this is the 24valve head has the injector under the valvecover centered in the combustion chamber. Because of this the injectors are completely different.
Which means the lines will be custom. You will have to run 24v injectors but they will need to have the popoff pressures set for the p pump. Rich

[Vefreak]

When i say 12v, i mean 1st gen VE rotor pump. Lol. I know it sound ridiculous, but there are reasons. Now what are the benifits of running a 24v head? I've always been told that the 12v heads flow more air.

[SHughes]

I doubt the automotive industry as a whole would be running 4v per cylinder unless it worked, at least a little.

[VMacKenzie]

Originally Posted by Vefreak

When i say 12v, i mean 1st gen VE rotor pump. Lol. I know it sound ridiculous, but there are reasons. Now what are the benifits of running a 24v head? I've always been told that the 12v heads flow more air.

According to this the 24V head outflows the 12V http://www.pdrdiesel.com/oldsite/DodgePortedHead.htm

Another benefit (according to Cummins) is with the injector spraying in the center of the piston the heat is dispersed more evenly, meaning under high fueling the piston distorts less and keeps a tighter fit in the bore than the offset 12V piston (in theory anyway).