6.4 vs 6.7 build

Theredbeast06

Theredbeast06

New member
This might be the wrong place to put it but I was wondering what your guys expert opinion was on a 6.4 build versus a 67 build. It is going to be used for street and strip. Kinda a all around motor. Will have a 75/91 twin setup with really big sticks and triple cp3 setup with a 200/220 cam. Would it be better to have the true 6.7 or a destroked motor for a toy.
 
Some people will say they are not worried about cylinder wall integrity of a 6.7 block where others have cracked at unimpressive numbers. Obviously displacement is an advantage and if you want piece of mind without sleeving a 6.7 block the 6.7 block/5.9 crank is a good option.

Pay attention to what pro street/super street common rail cummins are doing. The fleece setup has proven reliable around 1500+hp.
 
Well Iv got a sleeved 6.7 block stock bore and stock lenght r&r rods but have a 5.9 and 6.7 crank. So I'm just tryin to see where most ppl stand with the two different platforms for durability and longevity
 
Theredbeast06 said:
Well Iv got a sleeved 6.7 block stock bore and stock lenght r&r rods but have a 5.9 and 6.7 crank. So I'm just tryin to see where most ppl stand with the two different platforms for durability and longevity
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I don't understand the point of sleeving a 6.7 back to stock bore?

On that note whats the most anyone has bore a 6.7 block .100 .125? Obviously with the intention of sleeving it.
 
If you have a sleeved 6.7 block, my vote is for the 6.7 crank. Tuning of the final setup will have a big influence on the longevity of both setups.
 
There was one hole that had a scare in it so I told them to just sleeve all them to help keep the pressures inside they bored mine .1875 with is 3/16 then put Dayton sleeves in it I believe. The sleeve is suppose to be tougher then the cast block so I figured it help hold the cylinder pressures
 
Theredbeast06 said:
There was one hole that had a scare in it so I told them to just sleeve all them to help keep the pressures inside they bored mine .1875 with is 3/16 then put Dayton sleeves in it I believe. The sleeve is suppose to be tougher then the cast block so I figured it help hold the cylinder pressures
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Being that there's roughly 1/2" bore spacing I would say you might run into some issues taking that much material out. That would leave roughly .146" between cylinders without sleeves.

If the sleeves are that thick then it should be able to hold quite a bit of power.
 
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They didn't hit any water jackets...I just left it up to them and they said it worked out. Il ask tomorrow unless they decided to drop down to 1/8 at the last min
 
Whats the cost to sleeve all 6?

What unimpressive numbers cracked the cylinder walls? Were they at stock bore or over?
 
Well I've got a clean bore block that I paid good for so I was hoping to just go with that. Will I be good at 1000 with 366/73/1.0 sxe & bullseyes 483/96/1.1 and +1mm head with P&P & side draft? I'm thinking the head should reduce stresses a lot and make it a very safe setup. I'll street it at 900'ish and turn up over 1,000 a dozen times a year maybe.
 
I'd go 6.4 for rpm but only if you have the head flow to make power at rpm and very large injectors to keep timing down. 6.7 if it's going to be more of a street toy, will have more torque but will be harder on the rods.
 
Well Iv got a p&p head zz fab sidedraft 400% over injectors with triple cp3s and sleeved 6.7 with billet rods , coated and cut Pistons and around a 200/220 cam with a 75/96/1.32 t6 over a 91/112/1.24 t6. I went large enough on the injectors that timing will be in check and ported the head to flow at rpms north of 3k and a cam to keep up with lift. Here's the kicker I'm wanting to still street drive it ocusally...now I did daily a s480 single with 280% overs so I'm not stretching it to far I don't think with twins
 
Is the consensus saying it's not a good idea to sleeve a 6.7 block back down to the stock 4.21" bore if it will need bored at least .020 to clean the cylinders? What would be the best way to go when trying to ultimate realibility when pushing for 1100+ and wanting to keep the block together? Sub'd in for info.


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I'm assuming you have EFI revs? Sounds like you are going for a lot more than me in power with those huge injectors. Street driving 400%'s? How soon will yours be done you think? I think I'll just watch and wait. I also only have UDC revs and tuning abilities.

Whats best bang for the buck on main girdle?
 
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