morkable

So I have been reading my little butt off lately, and it seems to be surfacing that guys that are running the 6.7 block in extreme applications are having issues with the block cracking etc, on top of the rods bending etc.

Seems that the concensus is that you have to run billet rods, a girdle and fill the block and even then they will still sometimes crack..

I am starting to think that I should possibly shift back to a 5.9, I have a set of good 12v rods that are just out getting peened and cryo'd. Basically I have almost everything I would need to make a 5.9 run.... other than a 5.9, but I see that there are few around for cheap on kijiji, should be able to find a good block and head for 1000 to 1500... about half the price of the billet rods alone.

What do you guys think?

dvst8r

My opinion is and always will be:

5.9

Unless you can afford to put a deck plate on, rods, pistons and have custom darton sleeves put in it. Even at that point I think you are money ahead to just put rods and monotherms in a 5.9

Kev where you want to take even the 5.9, cryo'd / peened rods, will not hold up. If you are content at about 1000hp then run them, if you want to try for 1200+ then they are just a liability waiting to fail.

morkable

I think that for the next year I am going to hold it back to around the 1000 1100 hp mark... I just cant afford to play otherwise.

Mike Holmen

Kev, I really don't like all the swiss cheese lack of deck surface on a 6.7L, which will make head gasket choice more critical.

Its fairly easy to build a decent 1000+rwhp 5.9L without breaking the bank account. Not sure on what nozzles you bought for your F1 injectors? Would be nice to match the nozzles to a piston bowl. The newer 04.5-07 piston bowl probably makes the most power for a 5.9L, but I would only run mono-therms at that point.

winkdemon

i think the 5.9l is a better one to go with , lots of parts around and seem to stand up for the most part when there put together right , i have seen a cracked 6.7l in a 5500 stock hp level so that doesn't say much for them and all the head gaskets blow that i have fixed on them . and i dont work at a big diesel shop

morkable

Mike my injectors are for 03 04. So I will be probably running either a stock 03 04 piston or a set of qsb's (if I can afford too) I am going to use the 12v rods that I have already,, I feel pretty confident in those. (I raced and dyno'd for almost 3 seasons at 1000+ on stock CR rods until the injector hung.

One question though,, do you think that using a MLS headgasket and 625's will hold 100 lbs of boost?

dvst8r

Kev,

I had a big long reply written up, but decided I will just call you instead.

morkable

Hey Brett, was that your cell phone that you called me on, or your house phone? Could you give me both those numbers so I can program them into my phone?

dvst8r

Pm'd you with both.

Mike Holmen

I would run the QSB 480 piston, we are building an engine very similar to this currently. The QSB is priced decently and has 30% more heat treatment than the stock 03/04 piston. The engine build pricing is very decent for what your getting.

The biggest issue with head gaskets is getting the surface of the block and head as true as possible. We surface both the block and head. The protrusion of the piston from front and back is measured to ensure that the deck surface is true. I would get the rods bushings done and make sure that the large end is still circular. Cummins has a decent deal on the reconditioned 12V rods, hard to beat. New bushings, new rods bolts, and the large ends are in spec.

I have a spare set of 03/04 monotherms and R&R rods available.

morkable

I wish Mike. But out of my price range for this year. I have a brand new set of 12v rods right now, they are out getting peeked and cryo'd. Hope to have them back fairly soon. I am goi g to see where the best price is on the qsb's. Do you think a person should get them coated?

Nomad

Hurry Kev! Get that thing done, i want to see it tear up the track this year. I'd be happy to stop by and give you a hand--when i manage to get back into town that is!!!

morkable

When you back?

Mike Holmen

To me, the coatings are probably not worth it. The extra money would be better spent on buying mono's or putting the extra money into the head/cam. The coating never seemed to helped Torrey's truck last year.

Would be cool to see you pull a low 10 sec pass out of the old girl.

The guy that we are building the current QSB480 engine is planning on spraying as well, but probably not to the same level as you are. He planning on running the black out event as well, but in the bracket class.

Nomad

At Albian on another shovel, headed home on the first. If you're around I'll pop by for a visit in the next few days.