T7 intake valves

[squaab99t]

I was at Scanwest yesterday and Rob Walden showed me a T5 head with the 7mm stem intake valves (T7) installed. Requires new guides and seals. Drops static compression by 3cc per cylinder. And the skinnier stem for better flow.
Any of you hotrodders try this yet? I have a B204 head that I might use as a donor.

[Jordan]

I looked at them years ago and the T5 valves are already pretty slimmed down above the valve seats. I know the T7 valves are some special nickel alloy , but they are so spindly looking it was kind of questionable whether it was a move in the right direction. Between that and the compression loss it seemed more trouble than it was worth. The T5 intake valves are larger than the C900 valves. On the old race car I had one engine with T5 valves and another with standard valves, both with 2.1 head/intakes. The T5 valve car just had more lag and delayed torque onset. I don't really see a benefit besides maybe a lighter valvetrain, but you'd have to combat all the other negative effects for that to be worth it.

[squaab99t]

Thanks Jordan for running thru your experiences.
I remember Mezzanine had some flow bench testing done. The guy who owned the machine shop thought the T7 valves were from a motorcycle engine.

[Jordan]

I found a photo I took when I was comparing the 3 intake valves. b202, b2x4 & b2x5

[squaab99t]

Thanks for the picture. I did not know the 204 was necked down. I assumed it was skinny the full length like the far right.