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Exploring the 4U-GSE/FA20

Posted: Tue Dec 13, 2016 8:07 am
by oldeskewltoy
I got this in the mail about 5-6 months back.........

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and a bit closer a view...

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more to come.... :mrgreen:

Re: Exploring the 4U-GSE/FA20

Posted: Tue Dec 13, 2016 2:12 pm
by oldeskewltoy
It has a 2 part head, the valves, and valvetrain mount on the inner section, while the camshafts mount in the outer section. If you look carefully you can see some damage on the far side of the cam carrier.

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The intake valves are 35mm, the intake throat measures 30.8mm, or 88% of the valves diameter.

The exhaust valves are 29mm, the exhaust throat measures 24mm, or 83% of the valves diameter.



more to come...... :mrgreen:

Re: Exploring the 4U-GSE/FA20

Posted: Sat Dec 17, 2016 9:40 am
by oldeskewltoy
Checking out the exhaust alignment.........

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this will need further investigation..........



more to come...... :mrgreen:

Re: Exploring the 4U-GSE/FA20

Posted: Sat Dec 17, 2016 5:53 pm
by oldeskewltoy
oldeskewltoy wrote:Checking out the exhaust alignment.........


this will need further investigation..........



more to come...... :mrgreen:


Best way I know of to "see" what is going on.... make a casting!!!


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more to come...... :mrgreen:

Re: Exploring the 4U-GSE/FA20

Posted: Tue Dec 20, 2016 8:56 am
by oldeskewltoy
oldeskewltoy wrote:Best way I know of to "see" what is going on.... make a casting!!!




and so I did....... (Club4AG can't display the full image so click on thumb to see it full size)

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more to come......... :mrgreen:

Re: Exploring the 4U-GSE/FA20

Posted: Tue Dec 27, 2016 10:05 am
by oldeskewltoy
This doesn't look good.... not only is the one pair of ports longer, and more oddly shaped(more drag??), but they are narrower as well??? Can't tell for sure until I get this on the bench... but I do not expect equal results...... :(


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more to come........ :mrgreen:

Re: Exploring the 4U-GSE/FA20

Posted: Wed Aug 23, 2017 6:22 pm
by GZE_RA21
I know this is from almost a year ago.... but did you ever get anywhere with this OST? I found this short thread very interesting.

Re: Exploring the 4U-GSE/FA20

Posted: Mon Aug 28, 2017 4:14 pm
by oldeskewltoy
GZE_RA21 wrote:I know this is from almost a year ago.... but did you ever get anywhere with this OST? I found this short thread very interesting.


not very far at all.... began a flowbench tool for setting valves and got side tracked... didn't finish it....... :(

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Re: Exploring the 4U-GSE/FA20

Posted: Fri Sep 08, 2017 10:09 am
by aukword1
very interested in this thread since I just picked up a GT86.

Re: Exploring the 4U-GSE/FA20

Posted: Sat Sep 09, 2017 5:04 am
by Jayrdee
oldeskewltoy wrote:This doesn't look good.... not only is the one pair of ports longer, and more oddly shaped(more drag??), but they are narrower as well??? Can't tell for sure until I get this on the bench... but I do not expect equal results...... :(

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more to come........ :mrgreen:



That's interesting. The only thing I can think of, is maybe they made the odd side narrower to keep the air flowing at the same rate. What the longer side lacks in volume, makes up in velocity?


a little off topic, but I read an interesting article that rumored that Yamaha helped develop this version of the boxer motor. It makes sense, since Yamaha was the mastermind behind the 4ag, and all the other famous Toyota motors. So even though its made by Subaru, i'd say its still in the Toyota family if Yamaha was behind t 8-) 8-)