02-15-2008, 08:36 PM #1
The Stock Valve springs and why you should not use them
I been recently asked to repost my info on valve springs and what i know.
The F12x F12 and R12x R12 all use the same outer Valve spring, This spring is known to weaken under boost and with a modified Ski you are just asking for problems. Some people have reported that by using the non-turbo dual springs that the problem is solved.
So I ran a test 3 years ago and found out different, In fact the extra spring only adds about 5 lbs of pressure to make a total of 50 psi.
The problem is you still have the weak outer spring to deal with, so I scraped the idea and had my own kit made to fix the issue.
The Nitro spring kit come with 90lb springs (installed height VS 50lbs stock) titanium retainers, and a harden shim pack.
The Valve Tester I use:
The Stock Honda parts bought new for testing:
Nitro Springs Left, Stock Duals Right
optional Nitro buckets for extra light weight.
Tested Both spring kits at 1.285-1.292 installed height:
Nitro Kit 90 lbs
Stock Kit only 50 even with the extra dual spring
If your going to run extra boost you need to address the spring issue or your valves may look like this.
Remember, ALL Honda turbos come with only one spring, And this is the one below.
02-16-2008, 01:31 PM #2
Seeing is believing.
Thanks for the post.
02-16-2008, 02:49 PM #3
02-16-2008, 10:23 PM #4
Thanks Nitro for the info. Its good stuff like this that gives us hope for the future. By the way what is the max rpms that these springs will be good for!!
02-16-2008, 10:58 PM #5
Good for 12K,
Much more than a PWC needs, but if you use a aftermarket camshaft they will handle .100 or more lift.
02-17-2008, 08:47 PM #6
Will anything else need modified to use the larger cams? Have you tested the performance increase? Thanks for the tidbits!!
03-13-2008, 11:06 AM #7
- Join Date
- Mar 2008
What is open height and open pressure of the stock spring plus stock spring diameter. I am going to research a beehive style spring from PSI or PAC.
03-13-2008, 12:45 PM #8Its good stuff like this that gives us hope for the future.
03-13-2008, 08:59 PM #9
1.285 installed but I use a different base circle, because of my custom cams. It's been so long that i have messed with a stock head I would have to go measure one or dig out my old notes of 4 years.
My valves are longer also.
04-28-2008, 06:19 PM #10
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