skunk2 pro vs pro "xp" valve springs
A month or two ago I posted questions about what valve springs to use on my 13.1:1 compression, 2.0L gsr build using pro2 cams. Had alot of excellent answers. Now I went to order my skunk2 pro valve springs and retainers yesterday and saw they have two options the standard Pro series valve springs and the "xp" valve springs, advertised specs are:
Skunk2 Pro Series Valve Springs
Seat Pressure: 80 lbs at 1.320”
Open Pressure: 226 lbs at 0.820”
Coil Bind: 0.720”
Skunk2 Pro Series XP valve Springs
Seat Pressure: 93 lbs at 1.320”
Open Pressure: 238 lbs at 0.820”
Coil Bind: 0.718”
My motor will be my daily driver and should see revs up to ~10k, just wanting to know which one is more suited for my build. Thanks in advance for the input.
Skunk2 Pro Series Valve Springs
Seat Pressure: 80 lbs at 1.320”
Open Pressure: 226 lbs at 0.820”
Coil Bind: 0.720”
Skunk2 Pro Series XP valve Springs
Seat Pressure: 93 lbs at 1.320”
Open Pressure: 238 lbs at 0.820”
Coil Bind: 0.718”
My motor will be my daily driver and should see revs up to ~10k, just wanting to know which one is more suited for my build. Thanks in advance for the input.
For that RPM, use the XP and be sure you check installed height and set the pressures up. You can shim it up a little....about .020 on the stock spring seat.
and any kind of valve train issue will be amplified by the stiff springs and big cams. so you better make sure to check everything often
Predicting rpm's before motor is tuned huh?
You aren't gonna make power anywhere near 10 grand. Come back down to reality and stick with the Pro springs.
You aren't gonna make power anywhere near 10 grand. Come back down to reality and stick with the Pro springs.
Trending Topics
Can't say I don't blame someone for shooting for the 10,000RPM motor. To be honest I'd love to build my motor just to do it once on the dyno, then come back down to reality.
I can almost guarantee that in that setup, rod stretch will become an issue at about 9500rpms.
I don't think people realize the clearances we are talking about on over 12:1 and Pro series cams.
I don't think people realize the clearances we are talking about on over 12:1 and Pro series cams.
Originally Posted by Larry @ Endyn
This engine produced torque that nobody’d previously seen from a B series engine of any displacement with power peaking at 280+ at 9500 rpm….and it wasn’t leveling off either.
Just like anyone else, I sometimes become overwhelmed by the moment and the old adage, “if some’s good, more’s better, and too much is best” took hold of my mentality….and that thinking proved costly in the end.
I made the decision to go for more rpm, as this thing would certainly top 300 whp at the rate it was running. I figured that about 10,000 to 10,200 would do it……………and it did. It also blew the engine up.
The quench distance, or piston to head clearance had been set at .032”, to effectively give us “zero” quench clearance at 9500 rpm, due to rod stretch. .032” caused the pistons to hammer the head pretty hard at 10,000+, ultimately work hardening the pistons.
#4 piston was the first to shatter, taking out the cylinder, the cylinder head, and a few more ancillary parts in the process. The debris from #4 was in turn distributed to all the other cylinders, courtesy of the intake plenum chamber, leaving no cylinder exempt from damage.
It was an expensive reminder that one needs to think (hard) before making any hair-brained decisions regarding rpm with any engine. You’d think that I’d have been old enough to know better, but……………...adrenaline can be a terrible thing.
Just like anyone else, I sometimes become overwhelmed by the moment and the old adage, “if some’s good, more’s better, and too much is best” took hold of my mentality….and that thinking proved costly in the end.
I made the decision to go for more rpm, as this thing would certainly top 300 whp at the rate it was running. I figured that about 10,000 to 10,200 would do it……………and it did. It also blew the engine up.
The quench distance, or piston to head clearance had been set at .032”, to effectively give us “zero” quench clearance at 9500 rpm, due to rod stretch. .032” caused the pistons to hammer the head pretty hard at 10,000+, ultimately work hardening the pistons.
#4 piston was the first to shatter, taking out the cylinder, the cylinder head, and a few more ancillary parts in the process. The debris from #4 was in turn distributed to all the other cylinders, courtesy of the intake plenum chamber, leaving no cylinder exempt from damage.
It was an expensive reminder that one needs to think (hard) before making any hair-brained decisions regarding rpm with any engine. You’d think that I’d have been old enough to know better, but……………...adrenaline can be a terrible thing.
It says up to "~10k" of course my tuner will let me know where my power level drop and safe range on rev limit, just wanted someone to clarify as to which one to purchase. Brian from skunk2 has gotten ahold of me to let me know the pro series would be the one I want not the pro series xp, I completely understand the clearance issues hence why I am having a reputable shop put together my long block and degree the cams and check p2v and v2v clearance since I do not own the right equipment to do the work myself.
Thread
Thread Starter
Forum
Replies
Last Post
integrawow
All Motor / Naturally Aspirated
1
Jan 23, 2009 07:14 AM







