Hybrid stroker project
11-25-2013, 05:59 AM
#498
Addict
Rennlist Member
Rennlist Member
Nice build, as always. 
Can you share some more details about closed deck block?
You are using steel wet sleeves and aluminum plate cut to size and pressed in, or is it some other approach?
Can you share some more details about closed deck block?
You are using steel wet sleeves and aluminum plate cut to size and pressed in, or is it some other approach?
11-25-2013, 10:30 AM
#501
Race Car
Thread Starter
The block was done by Dave with FRF. We had been working together on a closed deck design. I wanted a stf "flat deck" so that's where this one came in. I know he's been mia lately, but he is still around.
The block is still dry sleeved. Started with a late NA block. The perimeter and tops of the cylinders are CNC machined. Then the deck plate is machined and press fit. Then the bock is bored and also machined the the flange to be counter sunk into the plate. Using ductile iron allows for using a much thinner sleeve while retaining the superior strength. Tfe sleeves also sit against a ledge at the floor. The deck should be quite a bit more stable with so many attachment points.
Thom, those holes look to be steam vent holed that are in the cometic gasket.
If it really does what I think it will, I should be able to crank up the boost quite a bit. Once I have both cars where I want them, I'll push it pretty hard.
The block is still dry sleeved. Started with a late NA block. The perimeter and tops of the cylinders are CNC machined. Then the deck plate is machined and press fit. Then the bock is bored and also machined the the flange to be counter sunk into the plate. Using ductile iron allows for using a much thinner sleeve while retaining the superior strength. Tfe sleeves also sit against a ledge at the floor. The deck should be quite a bit more stable with so many attachment points.
Thom, those holes look to be steam vent holed that are in the cometic gasket.
If it really does what I think it will, I should be able to crank up the boost quite a bit. Once I have both cars where I want them, I'll push it pretty hard.
11-25-2013, 07:31 PM
#503
The block was done by Dave with FRF. We had been working together on a closed deck design. I wanted a stf "flat deck" so that's where this one came in. I know he's been mia lately, but he is still around.
The block is still dry sleeved. Started with a late NA block. The perimeter and tops of the cylinders are CNC machined. Then the deck plate is machined and press fit. Then the bock is bored and also machined the the flange to be counter sunk into the plate. Using ductile iron allows for using a much thinner sleeve while retaining the superior strength. Tfe sleeves also sit against a ledge at the floor. The deck should be quite a bit more stable with so many attachment points.
Thom, those holes look to be steam vent holed that are in the cometic gasket.
If it really does what I think it will, I should be able to crank up the boost quite a bit. Once I have both cars where I want them, I'll push it pretty hard.
The block is still dry sleeved. Started with a late NA block. The perimeter and tops of the cylinders are CNC machined. Then the deck plate is machined and press fit. Then the bock is bored and also machined the the flange to be counter sunk into the plate. Using ductile iron allows for using a much thinner sleeve while retaining the superior strength. Tfe sleeves also sit against a ledge at the floor. The deck should be quite a bit more stable with so many attachment points.
Thom, those holes look to be steam vent holed that are in the cometic gasket.
If it really does what I think it will, I should be able to crank up the boost quite a bit. Once I have both cars where I want them, I'll push it pretty hard.
I found an article that was about singe cylinder knock testing. Essentially, the theoretical knock limit for ethanol is... there is none. Obviously the user will find other limits to their power package in many different ways, but I am excited to be getting closer to a few of my engine buildups that will utilize the fuel to its full potential.
Why did you choose to reduce the compression? I don't see, theoretically, where this is needed with e85?
11-25-2013, 07:39 PM
#504
Rennlist Member
Hey Blown. We have spoken before about e85.
I found an article that was about singe cylinder knock testing. Essentially, the theoretical knock limit for ethanol is... there is none. Obviously the user will find other limits to their power package in many different ways, but I am excited to be getting closer to a few of my engine buildups that will utilize the fuel to its full potential.
Why did you choose to reduce the compression? I don't see, theoretically, where this is needed with e85?
I found an article that was about singe cylinder knock testing. Essentially, the theoretical knock limit for ethanol is... there is none. Obviously the user will find other limits to their power package in many different ways, but I am excited to be getting closer to a few of my engine buildups that will utilize the fuel to its full potential.
Why did you choose to reduce the compression? I don't see, theoretically, where this is needed with e85?
E85 is a significant improvement but it does not eliminate knock potential.
Peak cylinder pressure is a concern in our motors even if knock does not occur. There are several threads discussing this in detail.
11-25-2013, 10:55 PM
#505
Rennlist Member
Reduced from what? 8:5.1 is half a point higher than stock. For a 2 valve head which is going to run pretty high boost this doesn't seem to be crazy low c/r.
11-25-2013, 11:30 PM
#506
Addict
Rennlist Member
Rennlist
Small Business Partner
Rennlist Member
Rennlist
Small Business Partner
E85 can knock, though it is much more resilient to it than gas - both due to the octane and the cooling effect.
However, on E85 (or sufficient octane gas) these 8v 951 are not really knock-limited, but mechanically-limited. Specifically, head-lift & head-flex. As Shawn mentioned, this is directly related to peak-cylinder pressure.
Reduced compared to the common trend of tuner-car E85 approach...
But good to point out that it is still a small bump up from the factory CR.
11-25-2013, 11:40 PM
#507
Rennlist Member
ps...the work looks great too!! :-)
11-25-2013, 11:41 PM
#508
Race Car
E85 is about 108 (R+M/2 for our non-US folks, or somewhere around 113-115 RON). That's probably good for a couple of points in CR, ceteris paribus. But, in boosted applications, that's rarely the case. It certainly will knock if you throw enough at it. But there are tons of other factors.
Side note, I'm a 4V fan. Plug is in the middle of the chamber, good for about 3/4 of a point. And contrary to popular belief, you can tune them for lower end torque instead of upper end power.
Side note, I'm a 4V fan. Plug is in the middle of the chamber, good for about 3/4 of a point. And contrary to popular belief, you can tune them for lower end torque instead of upper end power.
11-26-2013, 12:04 AM
#509
Race Car
Thread Starter
Yeah 4v would be good , but right now I just chose the easier route. Really to make things less complicated.
In regards to CR. In my experience, its a bit of a balance. Kind of like choosing a turbo. I've tried higher compression on a 2.5 and found that it brought down the overall power potential on the 2v. I like to think of it as the path of least resistance. These engines have many weak points that will be exposed as power levels are increased (E85 or other). Cylinder pressure will find the fuse eventually.
Cylinder movement
Stock rods
Block and head flex (not sure which is first)
stud size and thread boss material
I'm hoping I have most of these addressed to stay together at 6-650rwhp. Other than a faulty old valve seat the last engine was very reliable at pretty high hp levels for my usage.
Obviously a 2v head will be a challenge.
If it has any problems along the way I'll just leave the power down. DSM's are much cheaper to replace lol
Back to CR...The real question is why did I raise it?... It was going to be 7:1
In regards to CR. In my experience, its a bit of a balance. Kind of like choosing a turbo. I've tried higher compression on a 2.5 and found that it brought down the overall power potential on the 2v. I like to think of it as the path of least resistance. These engines have many weak points that will be exposed as power levels are increased (E85 or other). Cylinder pressure will find the fuse eventually.
Cylinder movement
Stock rods
Block and head flex (not sure which is first)
stud size and thread boss material
I'm hoping I have most of these addressed to stay together at 6-650rwhp. Other than a faulty old valve seat the last engine was very reliable at pretty high hp levels for my usage.
Obviously a 2v head will be a challenge.
If it has any problems along the way I'll just leave the power down. DSM's are much cheaper to replace lol
Back to CR...The real question is why did I raise it?
... It was going to be 7:1
11-26-2013, 01:15 AM
#510
Rennlist Member
My motor is about 8.8:1 (despite what Andial used to claim) and is manageable with high octane fuel. Have to be careful with ignition timing advance or you'll blow the coolant out like Mentos in Coke bottle. Are you planning a cam to bring the dynamic pressure down? I'm not sure if Garrity is among us on the list these days (?), but he used to experiment with deck plates -- not sure he ever got it reliable as expansion rates differed, etc. I have a new block prepped for oversized studs (essentially 9/16") -- did you consider that? How about the bottom end for that much power -- considering stronger fasteners or shuffle pins?