We all know about the bored out gassers.. Can the 7.3 be bored out? if so how far? can it be stroked?

 

I think I saw .040 over pistons for a 7.3

Could be mistaken though...

 

I didn't think we could bore them out, due to our blocks deriving from the 6.9 and being bored out to make the 7.3. That's why we have to add a coolant additive to keep the cylinder walls from collapsing due to the thinner walls between the cylinders.
That's just from my understanding but not too sure.

 

Hypermax makes .020 over pistons, not sure if there is an aftermarket crank for stroking it.

 

All diesel engines should be using SCA's no matter if they are bored out of not.

 

I know they sell oversized pistons for the 7.3 IDI, not sure about the PSD, but would not recommend it, after seeing a PSD tore down being rebuilt, the cylinder walls are extremely thin already, this is an extremely light weight block, the block weighs half what a IDI block weighs, I wouldn't stretch it any further.

 

i dont know if there is an "off the shelf" stroker crank. i do know that you can spec one out and have it made.

some issues i see with stroking these engines:
1- there is already no room for stuffing the piston higher, so you will need custom shorter rods to keep mr. piston away from mrs. head.
2- with shorter rods, you will need to clearance the piston skirts and crank. $$$
3- compression will be raised, so now you need low compression pistons. $$$
4- the dynamics of a short rod stroker engine SUCK. you lose efficiency, and greatly increase piston/cylinder wall wear. also you raise the stress on the rotating assembly from the more "harsh" reciprocating action you have created. also your redline is lowered to keep your piston speeds from reaching warp ninja speeds.
5- custom ground crank......$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$

as for boring goes, i dont have enough experience with this engine in particular, but if the walls are too thin as some people have stated, you can have the block sleeved. and you can have someone make you any piston you want. they will even cnc your name in them if you want. is your wallet burning yet?

im not saying its impossible, but its certainly not a 347 stroker kit for your 5.0 mustang! i would be interested to see dyno results of a big bore stroker 7.3! if i had the money, it would be done to mine already

 

Black widow diesel can custom make you a short or long block bored up to .030 or .040 over. So I would say that they are boreable.

 

Mine is bored .030 and i have heard theres .045 pistons out there. I'm pretty sure there are sleeve kits out there you can put in them

 

what kind of numbers (hp/tq) can one expect to see with a .030 bore with basic supporting mods (air/exhaust/tuning) ?

 

also, what would the total displacement be with a .030 overbore?

 

Stock the bore and stroke 4.11x4.18 inches.
So V=pi* r^2*h *8 cylinders
=3.14*2.055^2 * 4.18*8
=444cid
If you go .030 over bore becomes 4.14 and
V=pi* r^2*h *8 cylinders
=3.14*2.065^2 * 4.18*8
=450cid
My gues its good for a few hp but prob very minimal. Less than 5

 

The benefit od boring and stroking on a gasser is the addition of more air and fuel at a burnable ratio above the piston. This is not really necessary on a turbo diesel due to the nature of the beast. A diesel does not need to run at the stoichiometric ratio that a gasser does, and a turbo can cram all the air and resultant fuel in that it needs. A turbo runs above ambient pressure so if you want more power, push in more air. The sky is the mechanical limits of the turbo (PSI), injectors (CCs), and the engine itself(EGTs). It makes it's own displacement. Most folks on this forum are pushing 2 atmospheres (15 PSI above ambient) while some at 3 or more.

This is why a 360 ci (5.9 24V) Cummins can produce 300+ HP and 600 ft/lbs and still get 22 mpg at 70 mph pulling an empty flatbed trailer.

My 444 ci (7.3 non I/C) can pull the same trailer and see 19.1 mpg. I am dying to get mine on a dyno.

Aaron