Considering replacing the 24V engine in my 2001 with 12V p-pump engine.
(Why? My brother in law's 1997 p-pumper makes my 24V seem like a tired fuel guzzling AMC Gremlin by comparison, all the while the p-pump's mileage is solidly in the 20's.)

I have a good short block from a 1992. I have access to an excellent 1998.5 head and p-pump.

Are the 1994-1998.5 short blocks the same as the 1992 short block?

Could a 1992 short block be used with the 1994-1998.5 head?

I assume the camshaft is probably different as other things like the front timing gear cover etc. Would install an aftermarket cam anyway.

What I am asking is if the piston design and compression ratio is the same.

Thanks

 

The 98.5 is a 24v and the pistons are diff. The 98 12v the pistons are diff compression but same design. short answer Yes on the 12v.

 

Have you considered just P-pumping your existing 24 valve engine instead of making it into a 12 valve? I'm not sure of the specific details, but it can be done, conversion parts are available, and there are several members here who have done it.

 

You can take a newwer Dodge with the common rail system and convert it back to a mechanical IP?

 

I would second this. If you are going to be rebuilding an engine, and your 24v is still good, swap the p-pump on it. If you have all the 12v parts laying around, the only thing you should need is the conversion injection lines. Converting a VE engine entails the same thing as converting a 24v.

 

im not so sure this is possible but id have to do some digging to see if the timing case on the common fail...i mean common rail wud accept a P-pump i dont think it wud. and on top of that you wud have to find different injectors as the common fails are electronic

 

Front of the blocks are different, so a p-pump case won't bolt up to a CR block. There are p-pump kits for a CR. Use regular 24v injectors in place of the CR sticks.

 

Well there you have it!!!

 

Thanks so much for the great info.

Did consider p-pumping the existing 24v, but haven't found any definitive information regarding mileage improvement and power increase.
The 12 - 14 mpg the 24V is getting is the prime reason for swapping out the engine.
I know (jealously) for a fact how great the brother in law's 1997 is in both power and mileage. Just seems reasonable to copy his setup.

 

Expect the same potential out of a p-pumped 24v as a p-pumped 12v. Everything is the same except the head design and pistons, and thats only bowl placement. If the 24v has a hurt long block, it won't fix the mileage, but if its an injection issue, it will.

Gotta remember every truck is different when it comes to mileage. My 12v doesn't get as good of mileage as my 24v did. I'm in the 18-19 range most of the time, broke 20 once. But 12-14 does seem low if you're empty.

 

Guys, I run my 95 12 valve back and forth to town and get 19 to 20 and I`am heavy on the right foot.I was told get her up to speed and then let it run. So I push the petal and don`t spare it at all. I can get 26 empty at 70 mph and do most every time I have did the math. You just won`t believe what I get towing at 55 mph (15) . I love my truck,I`am not the guy in your way towing my fiver also.

 

Must be the magical cummings engine.

 

The brother in law's 1997 I intend to duplicate gets that kind of mileage.
I have ridden with him on many occasions and observed the good mileage.

On a recent trip to deer camp I personally filled his tank right to the top of the neck, couldn't have got another drop in.
As a test I refilled the tank when we got there (160 miles, 2 lane state roads, stop & go through towns, moderate grades, no particular load on truck just a cap on the bed, guns and personal items), that fill up, again to the top of the neck, took 7 1/4 gallons -- and he didn't baby the truck, we were pulling grades with ease at 60 mph and stepping out on the straights. 22 mpg.

The best part is the abundant power that accompanies the good mileage. Had I used my 24v for the same trip I would been down shifting on grades and wound up using nearly twice the fuel.

I'd bet if the brother in law ran his truck at a steady 65 mph on a level interstate highway, the 26 mpg you experience would be just about right.

It took a long time (and hard) for me to accept what I thought was just the brother in law's braggadocio, but now that I actually verified the mileage and experienced the power that goes with it, the 24 valve, particularly at these rising fuel prices, just ain't cutting it.
.
.

 

Respectfully, the use of the smilies is rather puerilistic, don't you think.
Wouldn't a more honest approach be to articulate exactly why you have determined the guy is being economical with the truth.

 

Tate

No bs , don`t have to,I had a bad battery last summer and had a hesitation that I found was the fuel rod not getting 12 Volts. two new optima bats did the trick and the fuel mileage came back to where it was. The only issue I have with the truck is towing my fiver and making to much heat on steep grades. I have a single lock TC and a fan assisted trans cooler planned for this towing season.