Ford Power Stroke Nation banner

1 - 20 of 89 Posts

·
The Unseen Mod
Joined
·
4,126 Posts
Discussion Starter #1
Well I know we all see the same post how about starting a good discussion.

Lowering Compression on a 6.0 opinions and thoughts How much to lower,

How about working the bowl sizing ? .020, .030, .040 over good and bads for each, Whats good for daily driving vs racing.
 

·
The Unseen Mod
Joined
·
4,126 Posts
Discussion Starter #3
I've been here I only reply to question that require experience or indepth stuff. So I decided to start a discussion for the veterans to pick our brains.
 

·
Registered
Joined
·
166 Posts
Subscribed!
 

·
Captain Negativity!
Joined
·
3,109 Posts
Ok fine. I'll take the first position. .010, .020, 0.30, 0.40 isn't going to have much variance in them. Now if you said .120 over, then you would be talking about cramming a 6.4L sized piston in there. Step up into the over 4" crowd and now you are getting somewhere. We have the equivalent of a small block ford.

Dropping compression. There are some SAE white papers about them in relation to power output along with emissions. One of them went into detail about going from 13.5 to 20:1 and after a certain point going up there were no more increases in power, but only emissions. But there is a whole extra side to this. Rod ratio. This will determine the speed of the piston going up and then coming back down. Change rod ratio and leave the piston dwelling at TDC too long and you will melt that thing.

Port the heads. Equal out the air distribution. Take away the crazy drive pressure. Then you will see this thing wake up. And of course, biggest bore physically possible.
 

·
The Unseen Mod
Joined
·
4,126 Posts
Discussion Starter #6
Was waiting for you to chime in lmao. So bore to .120 over how does that affect the block ? Strength wise ? Wouldn't it weaken the block itsself ? Throwing 6.4 pistons heck why not Duramax piston , different style or work done to them.

Dropping compression isn't always that good either right, what gains can be made, what other troubles come with lowering compression. Drive pressures now what does this affect turbo ? Having pressure to spin
 

·
Captain Negativity!
Joined
·
3,109 Posts
Was waiting for you to chime in lmao. So bore to .120 over how does that affect the block ? Strength wise ? Wouldn't it weaken the block itsself ? Throwing 6.4 pistons heck why not Duramax piston , different style or work done to them.

Dropping compression isn't always that good either right, what gains can be made, what other troubles come with lowering compression. Drive pressures now what does this affect turbo ? Having pressure to spin
Where ever did you get that idea from? And the block wouldn't be any weaker. It's what international did to make the 6.4L.
 

·
Registered
Joined
·
1,606 Posts
Do some research about the correlation to valve to cylinder wall clearance and air flow. May engine builder that I have talked to will tell you that if air flow is your key you should get the bore as big as possible and even shorten the stroke if you have to.

The 5.9 Cummins has a bore of 4.02"
The 6.6 Duramax has a bore of 4.06"
The 7.3 Powerstroke bore is 4.11"
The 6.4 Powerstroke bore is 3.86"
the 6.0 Powerstroke bore is 3.74"
 

·
Captain Negativity!
Joined
·
3,109 Posts
Do some research about the correlation to valve to cylinder wall clearance and air flow. May engine builder that I have talked to will tell you that if air flow is your key you should get the bore as big as possible and even shorten the stroke if you have to.

The 5.9 Cummins has a bore of 4.02"
The 6.6 Duramax has a bore of 4.06"
The 7.3 Powerstroke bore is 4.11"
The 6.4 Powerstroke bore is 3.86"
the 6.0 Powerstroke bore is 3.74"
And which one of them had the pin closest to the rings again?
 

·
The Unseen Mod
Joined
·
4,126 Posts
Discussion Starter #10
Nice now its getting interseting
 

·
The Unseen Mod
Joined
·
4,126 Posts
Discussion Starter #12
Hahaha your funny, how about ill provide a month of living area n food, you work ur magic on parts n come up n help build :poke
 

·
Captain Negativity!
Joined
·
3,109 Posts
Hahaha your funny, how about ill provide a month of living area n food, you work ur magic on parts n come up n help build :poke
You know I'm 6' 270+. You sir may find yourself financialy ruined by trying to feed me.
 

·
The Unseen Mod
Joined
·
4,126 Posts
Discussion Starter #16
Haha come on jeremy waiting for youi to chime in as well, haha funny Doug. Food or dealership rate I'd pay for food lmao.
 

·
Captain Negativity!
Joined
·
3,109 Posts
6.7L compression is 16.2:1 See where I'm going.

And they have some nice pistons. Still too small though. But they run a much tighter top ring gap.

 

·
Captain Negativity!
Joined
·
3,109 Posts
Pins are damn near the same size. They make a .039 over piston for the 6.7L That would give you about .200 overbore. Now to measure the pin to piston face. Hmm Stock 6L rod. 6.7L piston. Compression would be low 16s.

6.7L runs a small block ford firing order. Interesting little things...
 

·
The Unseen Mod
Joined
·
4,126 Posts
Discussion Starter #19
The bowls look completely different then whats in a 6.0, how does that affect everything else.
 

·
Captain Negativity!
Joined
·
3,109 Posts
The bowls look completely different then whats in a 6.0, how does that affect everything else.
It deffinately goes toward reducing compression ratio. To me if you open the bowl up you are giving a larger surface area for the explosion to work over.
 
1 - 20 of 89 Posts
Top