6G Celicas Forums

is the 4th gen 3sgte a strong engine...better power over the others?

Crank and pistons are the same, rods are made of cheese, so no they are weaker.

ok so why does it have more power????

Higher compression pistons

head.

alll 3s are 1998cc

no engine comes with pistons higher than the deck unless its a custom stroker build and someone f*cked up the measurements and didnt check before ordering custom pistons.

Check this site out if you don't agree http://en.wikipedia.org/wiki/Toyota_3S-GTE_engine
it possible that the head also helps with this power increase, but the 4th gen compression ratio is 9.0:1 where the 3rd gen is 8.5:1

What I mean is that it's the head that makes it high compression, not the pistons.

All 3s-gte are 1998cc (499.5cc per cylender)

499.5cc / 8.5 = 58.76cc (per head chamber)

499.5cc / 9.0 = 55.5cc (per head chamber)

You see? Since the bore and stroke are always the same (86mm x 86mm), if the compression was raised using taller pistons it would take a different bore and stroke to achieve 1998cc

This is just to give you an idea, Pi * R2 * H obviously doesnt factor in piston crown and head shape, and piston ring recess, but you get the gist of it.

actually, taller pistons cangive you the higher compression ratio while still maintaining the same bore and stroke and therefore displacement assuming both pent-roof head designs are the same.
i just did the math and it worked out for me. the end result turned out to be that the 4th gen pistons are 0.717 mm taller than the 3rd gen pistons.

This post has been edited by azian_advanced: Apr 22, 2011 - 3:03 PM

Pistons are the same between 3rd and 4th, check toyodiy if you dont believe me.

There is debate if the rods are different, some places state the same part numbers, but i know people who have snapped rods on 4th gen 3s-gte, taken appart and confirmed smaller rods.

This post has been edited by Cuts_the_Pilot: Apr 22, 2011 - 8:16 PM

if the pistons are the same, then the 4th gen rods must be longer. it doesn't make sense for them to be shorter while having higher compression ratios.

unless the pent-roof shape of the head is shallower in the 4th gen.

wow I started a good convo....

Just heared from a reliable source that they are the same as beams 3s-ge rods.

change is in the head.

If pistons were taller using the same bore and stroke you would have higher compression but less cc's.

1998cc and 86mm*86mm seems to be consistent throughout all 3s-* motors.

WOW... im late...



i heard this also... (probably from you cuts?) i can personally say that the rods are the weak point in the 4th gen. Ive had 2 of them blow, both cases a rod was thrown. i got pics of it somewhere in here (the rod was twisted like a tornado) and the piston was pulverized to look like little bits of gravel.

the 2nd blown one cracked a piston, couldnt see far down enough to assess rod damage.

the bore and stroke is what determines the cc's. the volume between the top of the piston at TDC and head have nothing to do with it. you can verify it by doing this:

π * [(8.6cm/2)^2] * 8.6cm * 4 cylinders = 1998 cc's

taller pistons (or longer rods) will just shift the stroke closer to the head resulting in higher compression but won't affect its cc's.

lol, there wasn't any rod left

there you have it folks! i didnt think there was lmao!

moral of the story: 4th gen rods are indeed cheese! (as cuts would say)

This post has been edited by easternpiro1: May 6, 2011 - 4:16 PM

i bet they were trying to make them lighter and for got to make them stronger haha

you are correct. look at the Supra 2JZ-GTE and 2JZ-GE, they are both 3 liters, have the same bore and stroke, even have the same crank and rods. the GE has a higher comp piston than the GTE. the heads have NOTHING to do with compression ratio



you are right and wrong. shifting the stroke so the piston gets closer to the head means that it will travel farther away which increases displacement. thats exactly how you stroke the 2ZZ to 1.94L, you use the 1ZZ crank.

well what i meant was the locations of the pistons at TDC and BDC will shift closer to the head, so the length of the stroke remains the same. but yeah, the crank is what determines the length of the stroke.