(4G63 is 3.347" (85.0mm), 4G64 is 3.4055"(86.5mm) never heard of google eh?

the 4G64 has a very slightly larger bore (4G63 is 3.347" (85.0mm), 4G64 is 3.4055"(86.5mm)), but more importantly, a much longer stroke (4G63 is 3.46" (88mm), while the 4G64 is 3.94"(100mm)). However, the 4G64 shares the same rods with the 2G 4G63T. Thus, the deck on the 4G64 is 6mm higher to compensate for the longer stroke. This is the major difference in the block. A deeper stroke means less balance at higher rpms. The 4g63 has a close ratio between bore and stroke meaning higher revs without damage. However, the 4G64 will produce more torque at the same RPM.

:agreed:

 

Sooo.... how do evo drivers get away with 7~8k reving when they swap blocks

 

Thats the extreme end of things, a 2.0 can be pushed to 10K plus on the extreme side of things.

It all comes down to piston speed

 

Because they use the 88mm crank with the 4g64 block with the bigger bore for more torque and with the shorter crank they spin it to 9k or more safely because the rod ratio is correct.

Yea, the 2.1L "de-stroker" has an even better ratio of stroke/bore, making it an almost perfect square engine.

That and the rod angle is better and can handle more HP safely.

 

ok.... so... i understand that the bore is different and i am having my block bored to 87mm instead of the stock 86.5mm. I guess that other than on tearstone i am having a hard time finding pistons that go to the 4g64. at first i was thinking that any 87mm piston would work but then got to thinking that the height of the piston itself might vary? So any help with this would be greatly appreciated.

 

Slowboyracing.com carries 87mm 4g64 pistons with a lower compression ratio for boost. (thats where I got mine)

Roadraceengineering.com also carries them I believe.

Your best bet is to choose what brand you want, find a distributer, and explain to their tech people what you're trying to do and have them order it for you.

 

We carry them as well Tearstone Performance - CP Pistons - Mitsu 4G64 2.4L 16v - Set of 4

 

Is there anything to look for when choosing a brand? what has everyone had success with?

 

I think the brand Tearstone carries is a good choice. I went with Wiseco, just because its a well known brand.

 

Off the top of my head there are only 2 companies that make a piston directly for the 2000 and up SOHC 4G64. They are CP and Wiseco. Wiseco was back ordered and needed to produce another batch as of last month.

There is a difference in the DOHC 4G64 pistons as well as the pistons used for a 2.1L 4G64.

If you need pistons, source the CP's from Russ. They will do just fine. Don't worry when you install them and the pistons sit about 5mm below the deck surfact. They still have an 8.5:1 compression ratio.

 

ok... thanks for the input...i will order from rus. but... just so i learn something... on slowboyracings website.. the weisco ones that i would get would be the ones for the 4g64 block / 4g63 head combo... is that correct?

Yea, the 2.1L is a whole different monster alltogether. I wouldn't be worth it with our stock head, or even a slightly built up DOHC, you really gotta have something to support that high RPM's valvetrain wise.

Also, I have the pistons made for 4g64block and 4g63 head I think. They're supposed to be 9.0 compression with the DOHC, so they're probably going to be a bit less on my motor. This might be offset with the planing of the block/head, but I'm not sure.

 

ok... thanks for the input...i will order from rus. but... just so i learn something... on slowboyracings website.. the weisco ones that i would get would be the ones for the 4g64 block / 4g63 head combo... is that correct?

 

unless you want to eat a flywheel literally.

:lmfao:

Ok so what about when they use for instance one of SBRs 2.5 4g64 blocks slighty overbored with a 105-106mm crank i think it was. The pistons gotta be custom on that because of the increased piston speed due to the stroke too?? I believe the bore can be left the same, dont remember on that one... But with cams you would still only get maybe 7~8k is what youre sayin then, huh??:dunno:

 

The custom pistons are due to the larger stroke causing the center pin to need to be placed higher twards the top of the piston. If you used a larger stroke and left the stock pistons in, it would just slam into the head.

Very similar to when they throw a 2.4L crank into a 4g63, the stroke is larger and then the piston wrist pin must be moved closer to the top of the piston.

 

from what I can see there is no 2.5l 4g64 on slowboys site those are all subarus. Piston speed cannot exceed a certain ratio is what we are saying when you do exceed a certain point the life of the engine will be affected alot.

Maby he is talking about the Brian Crower kit, they make a "stroker" kit, but I don't see that on the SBR website :scratch: . BrianCrower.com

 

Your forgetting that the 4g64 has a 6mm taller deck the wrist pin location is unchanged for the most part

Well, if the stroke is increased from 100mm-->106mm that kinda eats up the extra cushion of the taller deck. I'm not comparing pin location with a stock vs built 4g64, rather a stock crank 4g64 vs a 106mm crank 4g64. Which would be the 2.6L Brian Crower sells. I have yet to see anybody run this setup, its only on their website. Maby its just a myth? lol

 

well SBR only has a thread on evoM takin orders for a built 4g64 but theres another they started about a 2.5 an a 2.6 both are esentially modded strokes, odds an ends, and pistons

 

ok so one more quick question just to verify since i did start the thread. lol. when ordering my rods...if i just want stronger rods with no change in length then i can order ones for the 4g63 because they are the same? is this correct?

 

Yea, but make sure that the wrist pin diameter matches the pistons you plan on running. Its not all universal. I had to purchase bushings, have them pressed in, and then machined out to my wrist pin diameter.

The length and rod bearings should be the same size as ours.

 

so maybe my best bet would be to find a rod and piston set? or where did you get the bushings from?

 

well my rod/pistons were supposed to be matched. At least I got that impression from SBR. I guess they had a brain fart, but I ended up purchasing the wrist pin bushings directly from Eagle, who makes my rods. They didn't have ones with the correct inner diameter, so I got bushings that were the right outside diameter, and the inside required machining.

 

do you happen to have the part number of your eagle rods or the part number of your pistons?