Nah, I was just contemplating that instead of making both bigger, use the available space and bring the exhaust valve size up to par and spend the rest of your cash on having the perfect camshaft cut.

since the h89 is 31 using the ratio I gave you and the fact 4 or more times more pressure is available for the exhaust you spend your money on a bigger inlet and suitable cam for your needs.

Yes I was saying if you have the exhaust 1mm smaller than the inlet there is nothing to be gained going that way due to the exhaust only needing to be round 70-80% the size of the inlet. If you go larger exhaust you risk overlap or losing inlet charge through the exhaust if valves are too close or cam has more overlap.

Since ex. valve on H89 is already 31mm & 4X or more pressure is avail. from exhaust spend money on a 40mm inlet valve & suitable cam for your needs. 40mm x 77.5% / 100 = 31mm or just try stock 37 x 31 H89 presto. Nissan engineers are clever cookies & gave us lots of good stuff.

Just remember it won't matter one bit how big your exhaust valve is if you can't get the fuel/air mix in.. You will just be wasting space with an over sized Ex valve if your In valve (or whole intake system in reality) isn't capable of getting it in.

Or putting it very simply, why have a 110l/m exhaust hose when your intake hose can only do 90l/m, you are better off balancing the flow so you get equal amounts in and out..

My answer is not scientific in any way, but my engine guy once said to me when I was much younger and I kept asking him about this. "Because your arsehole is smaller than your mouth". Never asked again.

hahaha, pearl of wisdom there, I like it!

Hahahaha, Thats gold!
Might be the opposite for Unfamilia though ;)

hahahaahahaHAHAHAHAH

^^^^ that's a great way to explain it hahahahaha
Topic closed lol
Now let the $hit talking begin

HAHAHAHAHA!!!

Ok, I'd settle for that answer.

D I wasn't second guessing you any of what you said. In fact, I don't believe those Japs' engineering degrees were bought like here in SA. I was simply curious as to there reasons, and as you've explained, they were power oriented.

Thanks Guys for all the input