Motor rebuild progress report

[Fnschlaud4620]

Well some of you may remember last summer my engine lost oil pressure and started knocking. I am in the middle of rebuilding it and I thought I would share my progress.

I got a good deal on the 14mm head studs so I picked them up and drilled and tapped the block. It is really easy to do.







I also heard that the 14mm studs pull the bores into hexagons so I am in the middle of making a torque plate. Here are some pics










The plate is not done yet, I still have to drill the holes and bore the center holes to size and make it so it fits on the dowel pins. It is 3" thick. Does anyone know the bore spacing on these engines?

I am making a bunch more stuff, I will have more updates soon!!!!!!!!![/img]

[rockjeep73]

looking good. just curious, how thick is a standard torque plate?

what are your plans for the build? pistons? compression ratio?

[DTanklage]

Does anyone know the bore spacing on these engines?

i dont, but i dont have a block sitting here either...lol

i dont think they have to be exact

the ones for v-8's are oversize arnt they? for honing over size bores?

that is going to be one nice torque plate

now you just gotta build you a 'hot hone'

[KTA]

Now all you need is a Rottler to deck that block with!

[cummins king]

looks good!!! were did you get the good deal on the studs

[Fnschlaud4620]

looking good. just curious, how thick is a standard torque plate?

what are your plans for the build? pistons? compression ratio?

I know for a BBC it is usually 2" thick

I am reusing my OEM cummins N/I pistons I compared them to what I think is the MAHLE 155 and they seam to be the exact same piston, but I may be wrong. even so, The bowls are much bigger than the 94-98s the and the first ring is down further. I am fly cutting them for a bigger cam and turning .020 off the diameter of the piston above the first ring. I am planning on running .007-.008 cylinder wall clearance and keeping as much compression as I can. I know I have to deck the block but I do not want to run the .020 over gasket.

those are my plans, for now although things could change.

[KTA]

Why take .o20" off the od of the top of the piston?

[Fnschlaud4620]

I have heard of it on pull trucks, saw a picture on the web of an Enterprise engine piston and it was done. I asked the guy helping me build this thing, who has LOTs of experience building Gasser engines in the 1500-2500 hp range says that it is commonly done to gasser engine getting sprayed HARD with Nitrous. His opinion was although it probably doesn't need to be done in my situation, he didnt think it would hurt anything. It is suppose to keep the top of the piston from scoring the cylinder under extreme heat.

I dont know! KTA what is your opinion?

[swank]

DANG!! looking good. can't wait to hear more about this.

[KTA]

It is going to put a lot more heat on your rings, and will no doubt put more soot in your oil pan, which is hard on bearings and wear in general. There is no doubt the top of the piston won't be able to grow .020" so you wouldn't have to worry about it scuffing! The top of the piston is already undersized from the skirt to allow for thermal expansion, personally I think its enough. If the motor is setup on the loose side it shouldn't scuff anyways. I would get a good thermal coating on the piston and not worry about it.

[rockjeep73]

I am reusing my OEM cummins N/I pistons... ...The bowls are much bigger than the 94-98s the and the first ring is down further.

I was under the impression that the bowls were the same throughout the years, anyone have any input on this.

As for the top ring, it was moved back down on the 96-98 215hp motors.

Also, why do you want to keep the compression high?

[KTA]

There were 4 diffrent bowl designs for 12V trucks.

[DTanklage]

elablorate plz

i know my '97 has the preferred bowl (!)

yea, i didnt get all that piston stuff either...

nos (and turbo) motors usually do better with the ring down as far as there is room to put it

for pro stock type na motors you want it as high as you can get it

[Fnschlaud4620]

I did a lot of research pertaining to MAHLE pistons for my engine. I only found 3 that were offered.


Part number 2862100 2861100 2863100

compression 71.6mm 71.5 71.6
height

bowl depth/dia. 17.7/59.12 17.4/64 19.3/59
in mm

total length 105.4 105.4 105.4

top ring keystone keystone rectangular

ring placement low low high

I compared the 2862100 to my 91 N/I pistons and they were identical. I am GUESSING that this piston is A.K.A. the Mahle 155 which is talked about on other sites. If I am correct there are some running over 1000 hp on this piston.

The 2861100 appears to be MAHLES version of a marine piston. It differs from the cummins 370 marine significantly. the cummins marine 370 has a double keystone ring design, and the ring placement is higher. also it comes with a factory coating on the skirt.

The Mahle 2863100 appears to be a piston for a naturally aspirated cummins due to high rings and a rectangular ring design.

I have also seen the factory cummins pistons out of a 97 180 hp engine. The bowl design was very small but high swirl. also the rings were placed high. The first ring was also keystone design.

I have never seen a 215 piston. How do they compare? Why do they have a preferred bowl design?

On a side note, please dont take this information as facts, because I am not 100% sure these are just my observations.

I found the MAHLE 286210WR which is for "with rings on" at my local auto value store. I got them for 66.00 ea for another engine.

hope this helps,

Later,
Fnschlaud4620

[DTanklage]

the thing in the bowl is pointed, like a pyramid, instead of that big 'flat topped' thing that is in the first gen pistons