6.7 Block issues.

RonA

RonA

Active member
Joined
Feb 26, 2008
Messages
11,068
After starting my 6.7 project(and getting too far to turn back:hehe:) the info started trickling in about them splitting the block. Since that time I've been trying to keep the torque and timing levels down but still make as much power as the 5.9. I was pleased to make 980's and 10.9 with the 6.7 knowing that I should expect a drop in power with 4 degrees less timing and without adding additional fuel to make up for the displacement. I hated to drop 100hp but the drivability is better. By going to a wider spray pattern, water/air between stages, and more fuel I'm hoping to get back up to where I was but keep my timing down to 22-24 degrees. Does the difference between 22 deg and 30 deg make a lot of difference in terms of block stress, or is it really negligible?
RonA
 
I see you guys looking down on the bottom of the page. PM me if you don't want the info out. Or let me know where to send the check if I need to pay for the advice.
 
You must have seen the split twin p pump truck motor and now your getting worried. Every widowed motor i see makes me scared. Just buy a entire engine diaper. lol
 
From the people I have talked to since starting my p pump 6.7 build 1000hp and twins with a 6.7 block is playing with fire. Guess I will find out I am gonna try anyhow.
 
Hard to find a good used 6.7 that isnt split in half or has a windowed block.
 
Subscribe.

Not to derail thread. But how would a person keep from splitting the 6.7. Just curious.
 
Whats tbe deal? I'm so cornfused here.... one thread on here the truck pullers are swearing the 6.7 is the shizz (thread about troyers new engine & mention roarks 6.7 3.0 engine) & can handle that stress (1200+ fwhp) if built correctly. Now in here, & whispers elsewhere, folks claim they can't handle twins making 1000? Which is it?!?! Are the 6.7s legit or inherently flawed somehow???
 
Haisley and Kellogg told me high 30's on timing, 5K rpm, and 1800hp, and they'd be fine. Bump the timing to the low 40s, and it would split the block every 5-7 hooks, so timing does play a huge role. With low boost and an efficient setup, AND, with low timing, I'd say you'll be fine. You can always drop an extra 10K for machine work and end up with a Super B that is safe to 2500hp :rockwoot:
 
SmokeShow said:
Whats tbe deal? I'm so cornfused here.... one thread on here the truck pullers are swearing the 6.7 is the shizz (thread about troyers new engine & mention roarks 6.7 3.0 engine) & can handle that stress (1200+ fwhp) if built correctly. Now in here, & whispers elsewhere, folks claim they can't handle twins making 1000? Which is it?!?! Are the 6.7s legit or inherently flawed somehow???
Click to expand...

Filled block and good machining on a competition engine is a lot different than factory-spec. My understanding is that the walls may be a little bit thinner, but the Siamese bores provide more strength. Once you fill it for competition use, you're only left with the upsides, and not the downsides. I do know that Chase Fleece did 1K+ with spray with a single with no issues on a mostly stock 6.7L
 
How many blocks that broke were running stock rods? I am betting very few were running an aftermarket or prepped rod.
 
Interesting topic, my 6.7L isn't making that kind of power but its making enough that I'm starting to worry about longevity. I look forward to more info on this.
 
I would be way more worried about the stock crank than the block

Sent from my SCH-I605 using Tapatalk 2
 
inline6power said:
I would be way more worried about the stock crank than the block

Sent from my SCH-I605 using Tapatalk 2
Click to expand...

Why is that? And the 1000hp I have been hearing as a breaking point is on cr setups with stock rods. I am hoping the p pump setup plus a not stock bottom end will help. I'll
 
ninerqb8 said:
Why is that? And the 1000hp I have been hearing as a breaking point is on cr setups with stock rods. I am hoping the p pump setup plus a not stock bottom end will help. I'll
Click to expand...

You'll what!? The suspense is killing me!:lolly:
 
Well I went with a 6.7 for the reason of block strength and obvious displacement. Being Ppump fed and should be competitive in our circuit here..with 2.6 trucks pushin 1100-1300rwhp.. We will see...
I've got faith in Drew.. With his motors out there proving them selves already.. I'm nothin but confident.

-Clinton
 
ninerqb8 said:
Why is that? And the 1000hp I have been hearing as a breaking point is on cr setups with stock rods. I am hoping the p pump setup plus a not stock bottom end will help. I'll
Click to expand...

Oh because I have seem first hand 4 or so broken cranks. All had billet rods. Crank let go well before a block. All over 1100 and some over 1300

Sent from my SCH-I605 using Tapatalk 2
 
You must log in or register to reply here.
Back
Top