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Discussion Starter #1
I know there has been a debate in the past over whether or not 5.7 heads can be used on a 6.1 Block. Seems there are several key differences between blocks and I want to clear up what I found makes this swap possible.

Here is the front of a 5.7 block. You will Notice generous water Jacket holes for coolant.



Here is the front of a 6.1 Block. More material around the cylinder bores but less water jacket hole.



Then the feed from the water pump into the heads on both blocks is located right there in front of the block. Also there is a coolant crossover which is where the water temp sensor is located letting you and your computer know how hot things are getting.




Here is the Face of a 5.7 block where a water jacket meets with the cylinder head. Notice the giant hole?



Here is that same hole on a 6.1 block if you look you can see the shape is similar But there is more metal on the 6.1 deck surface.



Here is where this gets interesting This photo will show the bottom of the 5.7 head and the water jacket hole as is untouched from Ma Mopar.


Notice anything in that picture? The hole is the same size on the 5.7 head as it is on the 6.1 block.

Here is the Oil feed out of a 6.1 block to feed the rockers and valve train with fresh oil




And here is the other end of that feed on the head (5.7 that is.)



Now here is where we get technical. The 6.1 pistons do protrude out of the stock block .004" and the bore size is 4.055 where as the 5.7 bore is significantly smaller with a 3.92 so if you use a stock gasket you run a risk of the piston striking the head.

Our test of this combo is meant for boost so we used a .074" head gasket Based off of the 6.1 heads gasket and a custom piston with a total of .003" out of the bore. Yielding a compression ratio of 9.1:1

You all might be wondering why I am pointing all of this out. Well it just so happens that last week we built the first 426 Stroker with 5.7 heads and I will be posting up Dyno numbers and Track times in the next 2 weeks. The engine needs some time to break in but has been driven 157 miles over the last 3 days and we hope to reveal the proud new owner in the next week or so in time for the Mopar SRT8 shoot-out at Great Lakes Dragaway on July 27th.
 

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Update??

Any update on this post? I've very curious....


I know there has been a debate in the past over whether or not 5.7 heads can be used on a 6.1 Block. Seems there are several key differences between blocks and I want to clear up what I found makes this swap possible.

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Now here is where we get technical. The 6.1 pistons do protrude out of the stock block .004" and the bore size is 4.055 where as the 5.7 bore is significantly smaller with a 3.92 so if you use a stock gasket you run a risk of the piston striking the head.

Our test of this combo is meant for boost so we used a .074" head gasket Based off of the 6.1 heads gasket and a custom piston with a total of .003" out of the bore. Yielding a compression ratio of 9.1:1

You all might be wondering why I am pointing all of this out. Well it just so happens that last week we built the first 426 Stroker with 5.7 heads and I will be posting up Dyno numbers and Track times in the next 2 weeks. The engine needs some time to break in but has been driven 157 miles over the last 3 days and we hope to reveal the proud new owner in the next week or so in time for the Mopar SRT8 shoot-out at Great Lakes Dragaway on July 27th.
 

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the question i have is...why would someone want 5.7 heads on a 6.1 block....(i seriously have no idea, can someone break it down for me in terms i could understand)
 

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From my perspective it's about "easing" into a 6.1 platform, especially given I've spent a fair amount on my 5.7's top end and am now looking at stroker kits as my next step.

If I get someone to really confirm the claims that the smaller ports on 5.7 heads and shorter runners on the intake provide the air velocity and produce monster low-mid range torque without any other significant issues then I'm willing to sacrifice a little on the top end typical with the standard 6.1 setup heads and intake.

If this setup is confirmed to work out ok, then I'll have to think hard about ordering a 6.1 based 392 stroker instead of a 5.7 based. I've already upgraded most of the other things that would be required, so I'll be good to go (I think. :> ).

I'm no expert, so this is all speculation and research for me. Just hoping someone can provide some details on their experiences.

the question i have is...why would someone want 5.7 heads on a 6.1 block....(i seriously have no idea, can someone break it down for me in terms i could understand)
 

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Discussion Starter #6
Well the car is running But it had a trans issue. So as soon as the car gets back on the road I'll update this post.
 

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Discussion Starter #7
the question i have is...why would someone want 5.7 heads on a 6.1 block....(i seriously have no idea, can someone break it down for me in terms i could understand)
It's really like workhorse said if you already have 5.7 ported heads this is a money saver.
 
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