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rizin
10-16-2009, 02:40 AM
Ok I love building things and thinking about building stuff. This is just a thought.

Ok first off I know I am going to here about not being able to stroke a 5s block. What about this thought. Using a 2mm or 3mm head gasket. Would make up for the 2mm offset grind of the crank using 3sgte rods. Depending on the pistons the 1st ring would be close to the top of the bore. Idea from MrTurrari on possible way to stroke a 5s.

The next thing is going to a .030 over bore piston. From what I have read would want to use a 98+ 5s block.

So now we have a a 2.3l long block with a large head gasket.

Now going to the head would run a 3sge head. Not for sure if I would go the route bajachris88 did running the 5s ecu or using the 3sge ecu setup.

So just putting this up to see what people thought possible downfalls could be. Maybe this might be possible who knows might try this build years down the road. Like I said earlier just a thought or a horrible idea but possible to me.

Sang
10-16-2009, 03:26 AM
The next thing is going to a .030 over bore piston. From what I have read would want to use a 98+ 5s block.

If you're going to get a custom piston made, why don't you just have them relocate the piston pin higher by 2mm to offset the 2mm longer stroke.

If I were to do a 2.3L, i'd do a long rod setup to keep the same rod ratio. Offset grind the crank to 93-94mm stroke.

Stock 3sgte setup is 86mm stroke to 137.9mm rod length giving a 1.6RR
Stock 5sfe setup is 91mm stroke to 137.9mm rod length giving a 1.51RR

The setup you proposed uses a 93mm stroke to 137.9mm rod length giving a 1.48RR

93mm stroke, 10mm longer rods at 148mm would give you a 1.59RR (close to stock 3sgte)
93mm stroke, 3mm longer rods at 141mm would give a 1.51RR

You'd now have to accommodate for an extra 5mm. I suspect a combination of moving the piston pin location slightly, and thicker gasket might work. Or use a 5mm thick deck plate, two gaskets, and custom headstuds. Then sleeve the bore.

rizin
10-16-2009, 03:58 AM
Help me with what the rod ratio effects. Sorry I do not know a crap load about certian things but some big v8's use ratios close to what I proposed right?

joe's gt
10-16-2009, 05:49 AM
I think it affects what rpm range you make your power. Not 100% on that tho.

I would also think a shorter rod ratio would be less reliable because the crank shape has to do more of the work of pushing the piston than a longer rod length which would lead to more "rocking" within the cylinder and faster wear.

rizin
10-16-2009, 09:21 PM
Thanks joe's gt so the angle of the rod would be greater causing more wear.

Sang
10-16-2009, 09:27 PM
"egging" the cylinder bore has been discussed quite often when dealing with stroking an engine.

Also, power is made in the head, not the RR. RR will effect revability. How many v8's do you see revving to 8K+?

rizin
10-16-2009, 10:35 PM
I wasent looking at 8k rev. The torque would be the big thing like most strokers. So doing what I said would not be a high rev engine. So with a stock red line of a 3sge head set by toyota and a balanced crank, 3sgte rods and custom pistons it would still be fun to drive. Cams to help with the displacement in the set rpm range I think would make a fun car to drive.

Sang
10-16-2009, 10:38 PM
If you want to know more about rod ratios and their effects, this breaks it down as simplistically as possible.

http://mr2oc.com/showthread.php?t=159687&highlight=rod+ratio

Roundy
10-17-2009, 12:48 AM
putting a thicker headgasket in is a bit of an average solution imho, another 2mm higher with the piston will likely have it protruding from the bore (not 100% on 5S dimensions) and i can't imagine a the head gasket will cope as well as the bore with the combustion pressures. You would be tripling the area they act on the head gasket....

Custom pistons with a higher pin height would be the best solution, and longer rods another good option if there is the space to shift the pin height higher.

rizin
10-17-2009, 02:50 AM
Thanks sang for the link I have bookmarked it.

rizin
10-18-2009, 02:12 AM
Ok well after reading on rod to crank ratios more wear for sure. Then you would have a peak in piston speed. So it would be there in the 5s design already but this would increase it even more with 2mm offset grind. Compared to the 3s rod to stroke.

So the wear of 100cc larger engine would be amplified in this engine build compared to a stock 2.2l.

I was thinking about this build beacuse I am going to build a 5s ge down the road the only diffrence in the two would be the head gasket and the offset grind.