Engine/Transmission (1994 - 1998) Engine rebuild time, have some questions

[mdivincentis]

Time to rebuild the 12v. Its a 98, had the #6 cyl melt.

Right now it has: 370's, mild porting, piers cam, and all the other misc. parts.

Questions are as follows:



>Genuine Cummins parts or not?

>Coat the pistons or not?

>I will O-Ring for sure-should I do the head or the block?

>There are marks on the pistons from the valves-how much do the pistons need to be relieved?

>Marine pistons or not?

>Anything else I should do while it's apart?







I want to have a reliable 450-500hp daily driver.....

Any input is greatly appreciated!







Thanks!

Matt

 

[Bandit1]

i just had my motor rebuilt by Doug Conrad at ADT,i love everything about this motor i just made a conservative 462 hp and this thing is just plain fun to drive. i was supposed to have my pistons coated buy time wasnt on my side, Enterprise custom cut my pistons to the size and bowl that i wanted. if there are marks on the pistons from the valves your cam isnt timed right or it is opening the valves to much, either is not good may want to check for a bent valve. go with a good billet cam, custom cut pistons to the injectors that you are going to run, oring the head,use studs, make sure the head and block are true, while it is apart make it bullet proof, i wish i would have gone wilder but i chose not to at the time. do it once and do it right.

 

[mdivincentis]

Thanks Bandit!



Anyone else have suggestions... . ?



Matt

 

[Vaughn MacKenzie]

I would definitely have everything nicely balanced

 

[BigBadDodge]

Like bandit said do it right do it once



I have had great sucess with my setup since it was built 3 years ago, I have the ceramic coated marine pistons wich go great with the 370's and will get you to the HP level you mentioned and them some. I am runing a single O-Ring as well, on the block, though again the head hasn't been removed for over three years. If something were to happen I could o-ring the head and go with a double o-ring set up.



What caused the melt down Matt ? well other then heat. are you taking advantage of water injection for cooling ?



BBD

 

[mdivincentis]

Thanks for the replys, guys!



BBD-I can not figure out what caused the meltdown. I had just replaced the headgasket; blew it w/ nitrous and too much timing. The motor had been together for a week when it melted. I was running about 90 mph @ 1200 EGT when #6 totally quit. I had noticed reduced power earlier that day... . There is aluminum all around the cyl wall, and the top of the piston is rough and looks a little funny, but not completely wasted, no erosion @ spray areas etc. There were bits of aluminum holding the valve(s) open, I think thats why it quit firing. By the way, cyls 1,2,3,4,5 look really good still.



I was thinking I should o-ring the block only, that way if I have to shave the head, i don't have to cut new grooves. Is that logical?



Do I need to worry about using genuine cummins pistons? I am leaning toward stock type vs. marine because I sometimes have to leave my truck outside w/o plugging it in and it can get as cold as -30 around here. I would think starting may become an issue w/ marine pistons... .



I am definitely going to get everything balanced well, and I think a Fluidamper harmonic balancer would be good also. I plan to see 4000 rpm every now and then, no more.



The 370s im not so sure about anymore; at 9000 ft elevation, EGT and smoke is already a nightmare, so EDMs of some sort may be on the list as well.



I have been using water inj. but not when this happened.







Thanks!!

Matt

 

[BigBadDodge]

I was thinking I should o-ring the block only, that way if I have to shave the head, i don't have to cut new grooves. Is that logical?





Matt

Makes good sense to me,



the Marine pistons won't be a problem at all starting, I used them for two years when mine was still a daily driver, little bit of white smoke till they get warmed up, other then that no issues, and with the ceramic coating they will handle more heat obviously. I am not sure of the $$$ diference but if your doing pistons I would go with the marines and be done with it, you may want more power later :-laf



BBD

 

[Bandit1]

i was quoted $75 a piston i believe to ceramic coat and teflon skirt them. starting wont be bad, my compression is lowered quite a bit so i can run some more timing and fuel, it has seen sub zero weather some and it just takes 2 cycles of the grid heaters. my pistons are like marines, they were machined by EEP to match the spray pattern of my 370's, and they arent flycut. i didnt go that radical, wish i would have now. spend some money once and build it right. Doug at ADT built mine right, i just wish i would have given him the go ahead to go more radical with it.

 

[mdivincentis]

Pictures of the valve mark on the piston for thekidfan... .

 

[drawson]

For over a year now I have had my engine done. I have alot of pics in reader rigs.

I had the ported head from Piers o-ringed & a reciever groove put in the block below it & another o-ring in the block out side of it and run a . 020 over copper head gasket. I set it up for twins. This set up was the late Nowel's (HVAC) idea.

My pistons are stock cummins pistons that I had coated by HPC, the high temp on top & their moly coating in the skirts.

If I was to do it over again today I wouldn't coat the tops. In the winter my motor take forever to get hot and I freeze my butt off every morning.



I suggest you spend the $ and get it balanced!! It is great to open my hood while running & not see the mighty cummins moving.



Piers was a great help to me while I was doing my overhaul in getting me info & great parts.



you can e-mail me at -- email address removed -- if you have any questions...

 

[DPS]

use cummins industrial pistons they have almost stock compression but a much lower top ring so you can fly cut for a bigger cam and it will still start as good or better than marine pistons. also th industrial pistons are a 100% duty cycle piston which is more durable than a chrysler/cummins combo



the lower ring placement increases durability when you remove material. the marine and stock pistons don't last very well when you start cutting valve reliefs because there is so little left above the top ring



www.dieselperformancesolutions.com

 

[Dieseldemon]

Be sure and check the piston cooling nozzles for blockage What kind of oil filter were you using?

 

[mdivincentis]

Jim-I have always used Fleetguard and NAPA Gold filters on this motor. I pulled the pan off a couple days ago and there was a bunch of crap stuck in/on the oil pickup. Looked like gasket material... .

So, I think that a clogged cooling nozzle is definitely possible! Pretty interesting, now that I have gotten over the fact that I have to rebuild my motor. Have the NAPA filters ever fallen apart like a Fram?



drawson-The builder I am using said he has VERY good results balancing these cummins engines, so I am gonna do that for sure.





Thank you for all the help/suggestions!!!!!!!



-Matt

 

[Vaughn MacKenzie]

I suggest you spend the $ and get it balanced!! It is great to open my hood while running & not see the mighty cummins moving.

Dee you commented the rods ranged 32 grams between the lightest and heaviest. That seems like quite a bit (if you consider the 4. 72" stroke). What was the variance on the pistons? Were the components balanced to within a gram?



Vaughn

 

[Dieseldemon]

Yes they have also Wix- Carcraft and Fram

 

[JWine]

Have you seen mahle pistons?

 

[Hohn]

Mahle pistons are of the highest quality, imo. You can run them nice and tight in the bores.

Pistons: light and tight is what you want. Tight fit in the bores (for stability) with the lightest weight you can get without compromising strength. The Cummins Industrial pistons are great I'm sure, but check the weight and I bet they are VERY heavy. An aftermarket piston like a Mahle or Arias is sure to be lighter for the strength. Do you need an extra-heavy-duty piston?? How often do regular Dodge pistons fail on these things where it's not excessive EGT or a clogged cooling nozzle??

I'd think you have plenty of cushion to go with a lighter piston and save some weight.

Make sure you get it coated. I like SWAIN TECH myself for a max-effort application. GoldCoat on top, and PolyMoly on the skirts.


If you're going to lower the compression a bit for performance usage, do it with pistons, not thicker HG. This saves more weight. It also preserves the bowl/injector relationship, since you can lower compression by reducing the OUTSIDE of the piston without affecting the bowls.

Then get everything balanced with your new super-duper lightweight pistons. They will have to make the crank lighter to do this.

In the end, you'll have a lighter bobweight all around, and the engine will rev almost like a gasser. You can really feel the difference. Sometime see if you can experience the difference between a 440 Mopar and a 400-based 451 mopar. The 451 feels like it's over 500 cubes because it's so much more responsive with the lighter internals.

You're not going to make a CTD into a Sprint Car, but that's the direction you should seek wrt responsiveness. Shoot for taking 10# out of the rotating assembly and you're doing really well.


For injectors, I'd ditch the 370s in favor of DDP honed 215s or some Don M one-offs. I've never liked the smoke of 370s. Too much smoke/EGT for the power.


JMO as a 24v guy... .