3S-GTE JDM 3rd Gen Turbo Engine Interesting change in Gen 3 and 4 engines

CJMR2T · 11-19-2009, 07:50 PM

I brought this up in another thread but figured I would make a particular thread just for this topic.

If you look at the exhaust ports of a Gen 3 or 4 3s-gte engine, you will notice that cylinder 1 has a larger port then the rest (2,3 or 4)...

I'd like to see if anyone has either direct knowledge of why Toyota/Yamaha would have done this and or everyones theory as to why...

I could understand if the Exhaust manifold was a true full individual runner manifold and they did it to cylinder 4 but neither are the case so why #1...

Larger port volume = lower port velocity, so why would they want to lower the exhaust velocity of cyl. #1?

Oteck · 11-19-2009, 08:06 PM

cyl 1 would be closest to the transmission no? isn't the tb on the gen4 sidefeed also closest to that cyl?

CJMR2T · 11-19-2009, 08:33 PM

No, cylinder 1 is furthest from the trans, closest to the belts..... Yeah, as far as I know Gen 4's have an end feed throttle body but they are adjacent to number 4, not number 1 and the port size question is for the exhaust, not the intake. Plus the Gen 3's have this change too and they have center feed throttle bodies..

The intake ports are the same, its just that number 1 exhaust port is larger then the other 3 exhaust ports.

11-19-2009, 07:50 PM	#1 (permalink)
CJMR2T Fabricator Join Date: Oct 2009 Location: Lakeland, FL Posts: 3,689 Thanks: 3 Thanked 356 Times in 337 Posts iTrader Rating: (4/100% )	Interesting change in Gen 3 and 4 engines I brought this up in another thread but figured I would make a particular thread just for this topic. If you look at the exhaust ports of a Gen 3 or 4 3s-gte engine, you will notice that cylinder 1 has a larger port then the rest (2,3 or 4)... I'd like to see if anyone has either direct knowledge of why Toyota/Yamaha would have done this and or everyones theory as to why... I could understand if the Exhaust manifold was a true full individual runner manifold and they did it to cylinder 4 but neither are the case so why #1... Larger port volume = lower port velocity, so why would they want to lower the exhaust velocity of cyl. #1?

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11-19-2009, 08:06 PM	#2 (permalink)
Oteck Eye'm the Str⑨ngest Join Date: Aug 2005 Location: Burnaby B.C. Posts: 4,947 Thanks: 11 Thanked 173 Times in 157 Posts Blog Entries: 3 iTrader Rating: (5/100% )	cyl 1 would be closest to the transmission no? isn't the tb on the gen4 sidefeed also closest to that cyl?

11-19-2009, 08:33 PM	#3 (permalink)
CJMR2T Fabricator Join Date: Oct 2009 Location: Lakeland, FL Posts: 3,689 Thanks: 3 Thanked 356 Times in 337 Posts iTrader Rating: (4/100% )	No, cylinder 1 is furthest from the trans, closest to the belts..... Yeah, as far as I know Gen 4's have an end feed throttle body but they are adjacent to number 4, not number 1 and the port size question is for the exhaust, not the intake. Plus the Gen 3's have this change too and they have center feed throttle bodies.. The intake ports are the same, its just that number 1 exhaust port is larger then the other 3 exhaust ports.