Thread: I've been to lazy to inform y'all...

...but as I've torn down both heads, 1st and 2nd gen QRs, one thing I noticed was the valves for the second gen QR is smaller. I need to reconfirm this as I haven't really looked at the heads in quite some time. Regaurdless of that, I only bring this up 1) I was looking into 1mm+ sized valves and 2) this should be a point on valve size for the 1st gen QRs. I know most would rather stick to the stock size but which is fine I guess, but who knows, most of us stay at the stock redline as well. Also something I need to note is that the combustion chamber is different between the two if you didn't know.Any ways , thought I would let you know.

The difference between them is .30 mm, noticable size visually, but performance wise..eh

16 / 15
I 35.45/ 35.75 mm
E 30.45/ 30.75 mm

u wont really gain any performance from 1mm oversized. ull gain the power from the clean up in the head

measure the exhaust ports!

Head is packed up ready to ship when ever some one buys it, but iirc the ports are taller and wider

Did u ever measure the length between the two?

Sorry, but no. That was one of those things that was burred in the back of my head that was obviously forgotten. It took me a while to bring this up and now the head is boxed up ready to be shipped for its new home, when ever that happens. If I decide to pull it out to take some pics of to put on ebay I'll take those measuments.

Originally Posted by CrickiKaze

The difference between them is .30 mm, noticable size visually, but performance wise..eh

16 / 15
I 35.45/ 35.75 mm
E 30.45/ 30.75 mm

The B16 Spec-V ONLY springs are way way better than B15 springs.. They are $14 a pop, same price as JWT. JWT B15 springs fit in the B16 head. We have a collection of springs from about 8 OEM varieties.

They sure seem that way, since teh exhaust valve springs are shorter than the intake springs. Lot of stuff going on in there. Can't remember if I posted teh spring rates on here or just on allsentra, well thats an intresting story in its self.

Originally Posted by Joe@2J-Racing

The B16 Spec-V ONLY springs are way way better than B15 springs.. They are $14 a pop, same price as JWT. JWT B15 springs fit in the B16 head. We have a collection of springs from about 8 OEM varieties.

Joe could you share the part number and spring rates?

here was what a local shop measured them at.

EXT
30 lbs @ seat
100 lbs @.400 lift
.480 coil bind

INT
30 lbs @ seat
90 lbs @ .400 lift
.460 coil bind

I think the numbers maybe mixed up between in and ex but I didn't take the head to them.

Originally Posted by Joe@2J-Racing

The B16 Spec-V ONLY springs are way way better than B15 springs.. They are $14 a pop, same price as JWT. JWT B15 springs fit in the B16 head. We have a collection of springs from about 8 OEM varieties.

But the website lists that they are not compatible with the b16


QR25 JWT Valve Spring - Cams/Head

just for reffrence

16's are in the middle, BC's next 2 and stock 15's on the outside


!6's in the middle, 15's outside