HOHN

Since so many of the parts between the 6.7 and the 5.9 are the same, what can we plunder to make more power?


I've wondered if the pistons on a 5.9 or short enough to allow using the 6.7L crank without smacking the head.

Stroking the 5.9 with the 6.7L crank would take you up to almost 6.4L and raise compression.

Maybe a thicker HG would allow the use of the bigger crank?

The rods and bearing sizes and all that are the same between 6.7 and 5.9.

jh

Tate

You'd need a taller deck, or a shorter compression height on the pistons to do the stroker. Would the crank even fit in the block? Custom pistons would be cheaper than a custom block I'd imagine.

HOHN

Custom block-- that's funny! Maybe for 20K or so!

The crank will fit in the block just fine. the 6.7 and 5.9 share over 80% of their parts.

As far as I know, the rotating assemblies are the same fitment, just longer stroke and bigger bore for the 6.7L. The rods are the same, but the pistons for the 6.7L are shorter to allow the longer stroke.

If I thought my block could handle being bored to the 6.7L size, I'd try it, but it's like 3mm larger, and that's too much overbore imo. Weak walls are not your friend...

lholley

If I remember right from my old hot rod days. A longer stroke with the same bore increased torque and lowered top RPM's. The same stroke with an increased bore increased horsepower and raised top RPM's. This was on gas engines, but since a diesel is by nature a torque engine, a longer stroke should help it. Another thing you would have to check would be that the piston skirt did not contact anything at the bottom of the stroke.
A vendor selling 6.4 stroker long blocks with a good cam already installed might make some money.

Larry

haloman

Really if you are thinking about using 6.7 parts you are going beyond the limits of street truck. The 5.9 block has been taken up to around 450 cubes in a pulling application.

Number47

just a thought, never have had a 6.7 apart but what about a 6.7 block and a 24v head and a P-pump??

Number47

or what about a 5.9L crank in a 6.7l block with 6.7 pistons and connecting rods. or 5.9l crank 6.7l pistons and 5.9l connecting rods??

HOHN

Why? Lots of street-oriented guys have pulled an engine and replaced bearings or such. By comparison, doing a "stroker" kit is easy.

braxton357

How much taller is the deck on the 6.7? Are the bottoms of the bores changed at all or the is the crank dropped any?

Tennessee 12v

I like it, would it work?

Tate

6.7 has both a bigger bore and a bigger stroke, so pistons aren't interchangeable. If what Justin says is accurate (have no reason to doubt him), the rods are the same. So you'd need custom pistons to keep the crowns from protruding out of the block too far with the 6.7 crank.

To p-pump a CR, you need a special timing case, a 12v case won't bolt up. I imagine a 6.7 would be similar. Still doable, just not as easy as a 24v.

Number47

what different about the gear case? if something needs to be machine that's easy for me to get done. my dad owns a machine shop. if its just completely different, are they available. to have the displacement is worth it in my opinion to build an engine. on a side note i just got a phone call from my buddies at the junk yard. they just got a 200hp 6.7L out of a UPS truck with my name on it if i want it.

HOHN

BUY IT!
(10 chacter limit)

Diesel- Dummy

The monster vp guy Mike has put a 6.7 with a vp pump in his black truck and makes a new gear casefor that

Philabuster

Have you asked this question at your new job or is talk about modifying the Cummins a taboo subject?