stroking a 944/968 to 3.2 L!
02-18-2002, 01:10 PM
#1
Addict
Lifetime Rennlist
Member
Lifetime Rennlist
Member
Thread Starter
stroking a 944/968 to 3.2 L!
Hello
who can tell me where to find a crank for stroking a S2 or 968 to a Turbo 3.2 L?
I think stroking instead boring the block would be better and safer for the engine.
Konstantin
who can tell me where to find a crank for stroking a S2 or 968 to a Turbo 3.2 L?
I think stroking instead boring the block would be better and safer for the engine.
Konstantin
02-22-2002, 10:09 PM
#2
Racer
Join Date: Nov 2001
Location: California
Posts: 374
Likes: 0
Received 0 Likes
on
0 Posts
Konstatin,
I considered stroking to 3.2 and larger. The problem was not in finding a crankshaft, we located a crankshft company that does outstanding racing crankshafts. The problem is that you may have to notch the block for clearance. How much structual removal can the block take? I would also have gone with a larger bore, but we would have to take a chance with a different gasket company. I was advised not to experemint on this motor (sound advice). My motor is sleeved and there is room for boring over. Never had a head gasket problem. The larger bore motors work best with concentric O-rings. Not necessarily a receiving groove, either.
I considered stroking to 3.2 and larger. The problem was not in finding a crankshaft, we located a crankshft company that does outstanding racing crankshafts. The problem is that you may have to notch the block for clearance. How much structual removal can the block take? I would also have gone with a larger bore, but we would have to take a chance with a different gasket company. I was advised not to experemint on this motor (sound advice). My motor is sleeved and there is room for boring over. Never had a head gasket problem. The larger bore motors work best with concentric O-rings. Not necessarily a receiving groove, either.
02-23-2002, 07:33 PM
#3
Addict
Lifetime Rennlist
Member
Lifetime Rennlist
Member
Thread Starter
hello
explain me "notch the block for clearance"
what is this exactlly?
Also what kind of gasket do you use now?
I think it is better NOT to o-ring the block.
Konstantin
explain me "notch the block for clearance"
what is this exactlly?
Also what kind of gasket do you use now?
I think it is better NOT to o-ring the block.
Konstantin
02-24-2002, 12:16 AM
#4
Racer
Join Date: Nov 2001
Location: California
Posts: 374
Likes: 0
Received 0 Likes
on
0 Posts
Konstatin,
With a longer stroke, the rods come closer to the bottom of the block. For clearance purposes, on some motors, the builder has cut away the portion of the bottom of the block that the rod would come in contact with. I do not know if it is safe to do this on a 968 block. My 2.5 litre had a groove and wire in the head and a receiving groove in the liner, not the block. My 3.1 uses concentric O-rings in the head only. I'll get you the info on the gasket.
With a longer stroke, the rods come closer to the bottom of the block. For clearance purposes, on some motors, the builder has cut away the portion of the bottom of the block that the rod would come in contact with. I do not know if it is safe to do this on a 968 block. My 2.5 litre had a groove and wire in the head and a receiving groove in the liner, not the block. My 3.1 uses concentric O-rings in the head only. I'll get you the info on the gasket.
02-24-2002, 01:16 AM
#5
Nordschleife Master
What is better for quicker spool up, an "out of square" motor or a "square" motor?
Or does it not matter since they move the same amount of air? I was disscussing this and we aggreed that the "out of square" motor would be able to spin faster, allowing to move more air in the same amount of time. <img src="confused.gif" border="0">
Or does it not matter since they move the same amount of air? I was disscussing this and we aggreed that the "out of square" motor would be able to spin faster, allowing to move more air in the same amount of time. <img src="confused.gif" border="0">
02-24-2002, 01:57 AM
#6
Advanced
Join Date: Feb 2002
Location: Seattle
Posts: 72
Likes: 0
Received 0 Likes
on
0 Posts
Here is a pic of what a notched block looks like. This is not a porsche block but I think you will get the idea. The scribe is pointing at the notch made to give the rod travel clearance at the bottom of the cylinder.
02-24-2002, 06:55 AM
#7
Burning Brakes
I would guess undersquare, based on the 1.8 VW/Audi turbomotor. Instant boost and torque at low rpm.
[quote]Originally posted by Lukesilver95186:
<strong>What is better for quicker spool up, an "out of square" motor or a "square" motor?
Or does it not matter since they move the same amount of air? I was disscussing this and we aggreed that the "out of square" motor would be able to spin faster, allowing to move more air in the same amount of time.
</strong><hr></blockquote>
[quote]Originally posted by Lukesilver95186:
<strong>What is better for quicker spool up, an "out of square" motor or a "square" motor?
Or does it not matter since they move the same amount of air? I was disscussing this and we aggreed that the "out of square" motor would be able to spin faster, allowing to move more air in the same amount of time.
</strong><hr></blockquote>
Trending Topics
02-24-2002, 12:36 PM
#8
Three Wheelin'
Join Date: Oct 2001
Location: Seattle, WA
Posts: 1,805
Likes: 0
Received 0 Likes
on
0 Posts
OTOH, oversquare will give you top end. The bore size maximizes valve area. The bore in an F1 car is something like twice the stroke. This allows it to have huge valves to flow air. It also allows them to run high rpms with relatively low piston speeds, which *partly* explains why they can run close to 20,000 rpms.
If you were to build a racecar for PCA GT3 racing, and you wanted to maximize that spec (under 3.4 liters na or 2.615 turbocharged) a 968 block and head would be your best bet. You could get some custom pistons and rods and use a 2.5 liter crank and end up with a oversquare motor which with the appropriate head and valvetrain work, could rev very high. They actually talked about this recently on Rob's board, but I think the primary aim was for strength, rather than for bore size.
The 944T isn't suited too well for the PCA GT1 class because the 911 guys can get their motors to 4.0 liters and put turbos on top of that. I imagine that is why Kelly-Moss decided to put a 928 engine in a 944 chassis.
If you were to build a racecar for PCA GT3 racing, and you wanted to maximize that spec (under 3.4 liters na or 2.615 turbocharged) a 968 block and head would be your best bet. You could get some custom pistons and rods and use a 2.5 liter crank and end up with a oversquare motor which with the appropriate head and valvetrain work, could rev very high. They actually talked about this recently on Rob's board, but I think the primary aim was for strength, rather than for bore size.
The 944T isn't suited too well for the PCA GT1 class because the 911 guys can get their motors to 4.0 liters and put turbos on top of that. I imagine that is why Kelly-Moss decided to put a 928 engine in a 944 chassis.
02-25-2002, 10:26 AM
#9
Addict
Rennlist Member
Rennlist Member
This 944T is competitive in PCA GT1 class...with the right driver of course.
3L (968 block w/ 8v head), Garret turbo, dry sump, and Electromotive ignition, Crawford composite body panels, big reds...
~450hp @ 1bar, ~550hp @ 1.5bar
This ran in Grand American GTO class for the 2000 season.
<img src="graemlins/burnout.gif" border="0" alt="[burnout]" />
3L (968 block w/ 8v head), Garret turbo, dry sump, and Electromotive ignition, Crawford composite body panels, big reds...
~450hp @ 1bar, ~550hp @ 1.5bar
This ran in Grand American GTO class for the 2000 season.
<img src="graemlins/burnout.gif" border="0" alt="[burnout]" />
02-25-2002, 01:33 PM
#10
Three Wheelin'
Join Date: Oct 2001
Location: Seattle, WA
Posts: 1,805
Likes: 0
Received 0 Likes
on
0 Posts
[quote]Originally posted by Sloth:
<strong>This 944T is competitive in PCA GT1 class...with the right driver of course.
[/IMG]</strong><hr></blockquote>
I may be mistaken, but doesn't Grand-Am require a restrictor that is dictated by engine size, induction method, weight, etc? I believe that PCA does not have the same intake restrictor requirements. It wouldn't surprise me to see PCA GT1R cars to actually go faster then their Grand-Am or ALMS counterparts.
<strong>This 944T is competitive in PCA GT1 class...with the right driver of course.
[/IMG]</strong><hr></blockquote>
I may be mistaken, but doesn't Grand-Am require a restrictor that is dictated by engine size, induction method, weight, etc? I believe that PCA does not have the same intake restrictor requirements. It wouldn't surprise me to see PCA GT1R cars to actually go faster then their Grand-Am or ALMS counterparts.
