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Old 08-18-2014, 03:26 PM   #41
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I have an extra set if anyone wants. New, uninstalled and unused.
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Old 10-10-2014, 02:01 AM   #42
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Default ZVS855 v. VS855

Back from the dead. I'm wondering if the big difference between Summit's ZVS855 and VS855 is the part number.

VS855 is a Volvo valve spring made by Federal Mogul. Made in USA. I've seen them panned here simply because they're so cheap--a whole engine for $60.

Update--if they're Sealed Power from Summit, then it's probably the same thing. The unique UPC code is 724956648306


Additional Details

Free Height (In): 1.810 Inch
Free Height (mm): 45.974mm
Type: Single
Minimum Closed Height (In): 1.570 Inch
Minimum Closed Height (mm): 39.878mm
Minimum Closed Pressure (psi): 66 psi
Maximum Outside Diameter (In): 1.056 Inch
Minimum Inside Diameter (In): 0.708 Inch
Minimum Inside Diameter (mm): 17.983mm
Maximum Outside Diameter (mm): 26.822mm
Minimum Open Height (In): 1.180 Inch
Minimum Open Height (mm): 29.972mm
Minimum Open Pressure (psi): 175 psi
Solid Height (In): 1.120 Inch
Solid Height (mm): 28.448mm
Total Coils: 7
Wire Diameter (In): 0.164 Inch
Wire Diameter (mm): 4.166mm

O'Reilly sells them for $3.69 each.
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Old 10-11-2014, 01:52 PM   #43
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Props to Dale for this thread! It helped me solve an issue I was having from not enough spring pressure.
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Old 12-16-2014, 01:39 PM   #44
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Hello. On the BP6D cylinder head, is there a difference between the stock exhaust valve springs and the intake valve springs?

I have been searching for a while but couldn't find out.
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Old 12-16-2014, 07:50 PM   #45
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Quote:
Originally Posted by AbeFM View Post

1) The VVT springs are NOT identical. Pre-VVT, they are speced exactly the same, but in my VVT head the intakes are painted yellow, are physically longer (free length) and more beefy and weigh more. So I'm not sure I will see the gains I would on a '99 head with aftermarket springs, but I'll still get something. I wonder when FM says "9,000 RPM" if it's for the 99 cams, the vvt cams, or the MSM cams.
This is what I was searching for I guess. Found it on this thread.
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Old 12-29-2015, 01:27 AM   #46
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Quote:
Originally Posted by BogusSVO View Post
18psi...A stock engine is NA, so it operates in a vacuume, springtions do not have to be as much as a Turbo engine.

When you add boost, the spring now has to hold the valve closed against the boost pressure.

With a stock 1.8 intake valve, there is appox 1 sq/in.

So the first thing you do is subtract boost pressure from spring seat pressure.

So with 18psi of boost, and 70lbs on the seat ( ST single if dropped in) leaves 52lbs of spring pressure to keep control of valve motion with the cam.

Factory spring is 43, so you have 9lbs more than stock.

Efini, Once I am happy with the set up, and get back with BC on them. I will let you know.
That's the intake side. On the exhaust side, pressures might be twice that (according to the internet).

A while back, I found that above 5500 rpm, the pressure at my turbine inlet was pushing open the wastegate valve and preventing me from maintaining my target boost, even with all the air bled off. It got worse the higher my RPM climbed.

It would not surprise me to find that I was getting 30+ psi of pressure between the exhaust valves and the turbine inlet at 18 psi of boost, especially at higher RPM.

Even with the double heavies, 30 psi of pre-turbo exhaust pressure would take you back down to nearly stock valve seat pressures.

Of course, me being a log manifold kind of guy, that might be contributing to the exhaust pressure.

edit- I went with supertech double heavies on my rebuild, should have dyno results in a few months
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Old 12-29-2015, 02:01 AM   #47
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I wish bogusSVO was still around. His **** was so informative.
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Old 12-29-2015, 03:00 AM   #48
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Quote:
Originally Posted by AlwaysBroken View Post
It would not surprise me to find that I was getting 30+ psi of pressure between the exhaust valves and the turbine inlet at 18 psi of boost, especially at higher RPM.

Even with the double heavies, 30 psi of pre-turbo exhaust pressure would take you back down to nearly stock valve seat pressures.
35 psi gauge is what I measured in the exhaust manifold at 18 psi of boost.

The thing about valve springs I don't get, though, is that that when the valve is closing that pressure is on both sides of it, so it really shouldn't make any different to valve float.

--Ian
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Old 12-29-2015, 03:40 AM   #49
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Two things:

1) The exhaust runners aren't isolated from one another in most turbo manifolds. Each exhaust stroke is forcing out gas that pushes the turbine blades but it also pushes against the wastegate valve and the other cylinder's exhaust valves. I suspect that more log-like manifolds are worse in this regard. By how much? No idea. The size of turbine you run probably also has an effect in terms of how much boost/rpm gives how much back pressure.

2) During the exhaust stroke, I would imagine that it's pretty even, but what about when the piston hits TDC, just as the intake valve is opening and the exhaust valve is about to close? I would imagine that cylinder chamber would be at its lowest right about then. And I think there's a decent chance at higher rpm/boost levels that the pressure on the backside of that valve should be pretty high.
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Old 12-29-2015, 12:04 PM   #50
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What are you using for valve spring compressors? For a number of other platforms there is a slick tool that bolts to the cam cap and allows springs to be changed with the head on.

Refference:

1
Valve Spring Compressor

2
Honda B18C B16A H22A VTEC valve spring compressor tool
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Old 12-29-2015, 01:12 PM   #51
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Consensus:

KD Tools Gearwrench Valve Service Kit
https://www.amazon.com/dp/B004ZG5LGI..._o6RGwb4ZEVJ6W
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