Jowett

A little late getting back to this one. No complete swap, though at times I do consider building a 3UR with the 2UR ISF heads…. but that would take quite a bit of custom work with aluminum.

I finally picked up some 1UR-FSE heads (same part # as the 2UR FSE from the LS 600), and the ports look to be the same as the 3UR. So they should flow about 295 CFM. According to the Yamaha Tech Paper, the 2UR GSE head flows 11% better than the FSE head at .5". This gives an intake flow rate of 327.5 CFM… that is very healthy!

MileHIFcar

^^Forgive my tech inexperience with this stuff, but does that mean the 2UR GSE motor can rev higher than 6800 and still make good power north of 7000rpm??

I thought I saw a tune from Japan (forgot thread name here) that pushed the redline to 7400rpm....I wonder if that tune used the flow rate advantage of the Yamaha heads for the higher redline?

Thx

Jowett

SARD/Novell. The engine can rev higher, but there's not much point... unless the tune opens up extra power up there. Perhaps they adjust the cam VVTi overlap?

rselby

Now that the ISF is being tuned ( can anyone answer if this ( adj the VVTi ) currently being with the tuner we have offered to us ) seems there is lots more potential to make more of HP with the above mentioned flow #s 327.5 @.500

viprez586

Bump for info on this!

Kind of a bummer the 2UR-GSE has peanut style ports.