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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.
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
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.
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.
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.
Hello,
I will try to recover this thread ...
I have not found the Sealed Power VS-855 valve springs for anywhere in the past 3 months. Investing I have found to which model of Volvo engine they correspond. It is a Volvo B18 and B20 engine valve spring, the part number is 418737.
After so long waiting, I decided to buy these springs in the following website: SKANDIX Shop Volvo parts: Valve spring 418737 (1000447)
I have received them and I have taken measurements with the micrometer and these are the results:
Free Height (mm): 45.98mm
Minimum Inside Diameter (mm): 18.00mm
Maximum Outside Diameter (mm): 26.84mm
Total Coils: 7
Wire Diameter (mm): 4.17mm
I have not been able to verify the strength (pressure) of these springs since I do not have measuring instruments and at this moment I am not sure that the result is the same as the Sealed Power VS-855
Has anyone been able to test these springs? Is there someone who has installed them in your head?
They seem exactly the same in the measurements but I lack the strength data to be absolutely sure before installing them in my head.
I will be very grateful if you can help me.
(Sorry for my English, I'm from Spain and I'm using the translator)
Last edited by jrmiata42069; 01-17-2019 at 04:35 AM.
In search of a viable VS855 replacement spring which shares the similar qualities, specifically fitting under the stock retainers & in a similar cost range.
I backordered these a few months back however Jeg's has pushed the date back each month - I reached out to Federal Mogul (Sealed Power) who said that the p/n is not discontinued but there is no ETA available due to no source. Their customer service experience was great for what it's worth, almost makes me not feel as bad that I'm back on the hunt for an affordable valve spring that fits under stock steel retainers (not a fan on Ti much)
Other than the OEM Volvo ones which turn out to be ~$250us, what are the other choices? The BC's at the start of this thread looks promising but there isn't a p/n available and I don't see them listed anywhere from Brian Crower dealers. Where are you hiding affordable single valve spring upgrade?
I've been through the same situation with Jegs for 3 months, it was exasperating. finally I bought the springs that I describe in my previous post and I have already installed them in my head.
You have to look for springs for volvo engine type B18 and B20, the OEM part number is 418737.
The Sealed Power VS855 It is an interchange spare part, there are several manufacturers as ITM, Perfect Circle, Sealed Power...
VS855 Interchange Part Number: 418737, 212-1241, VS437, VS1065, W11454. These are the same springs.
Here is a link where you can buy them: https://www.ebay.com/p/Engine-Valve-...0L-L6/79503613
Thank you for your research elpazos! So funny enough, Skandix has them for around $100usd, not sure what shipping is...but looking at the same part from US dealers comes out to around $250usd LOL
I'll post my findings if I come up with anything significant in terms of pricing.
*Edit - I just emailed their support to ask for an adjusted shipping rate. Its somewhat of a flat rate at 55 EUR which is more than half the cost of the parts - hoping they can adjust. I also found that they have an eBay Store, Skandix USA - however this part number is not available from their items listed. Also emailed the eBay USA side to see if I could order direct from there. This is the route I'm gong to go, just need to figure out a more realistic shipping cost.
***Edit 2 - The Germany/Sweden side will not budge on shipping. The USA eBay side does not stock the part or have plans of getting it. Shipping is flat rate to USA up to a certain weight, turns out to be $62.38 at this time of posting with the current exchange rate. The valve springs turn out to be $126.13 That makes the grand total $188.52 for those in the USA. I may have another update however, with another option. Doing the research now.
Last edited by _integrity; 03-18-2019 at 11:17 PM.
Reason: new info
Dang .. I just placed my Jegs order for these springs 2 weeks ago and it was supposed to ship today .. I see that the item page the date keep getting pushed back but I was hoping it was for new orders and MINE would be shipped on the correct date. Judging from your comments here I'm thinking I should just cancel my order.
10-10-2014, 01:01 AM
ZVS855 v. VS855
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