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Thread: Frankenstein valve options

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Posts: 1-10 of 12
2014-07-13 07:34:01
#1
Frankenstein valve options
Can someone please explain what it takes to make non-sr20 valves work in a sr20 head?

Supertech stuff seems to make everyone nervous, so what are the alternatives? I gather you can get around valve stem thickness using something like k-liner guides and non nissan valve stem seals, but what are the effects of a different valve length for instance? Do you just machine down the stem? If the keeper grooves are say 0.5mm off what effect doesn't his have on the installed height, spring rates, cam duration etc? Can someone please explain?
2014-07-13 11:28:38
#2
I think you may be biting off more than you can chew. I agree with you about the supertechs, I've read a lot of negative about them, not so much with the sr's. With valve height though the overall length of the valve length is not the most important, rather the seat to stem length. For instance when resurfacing valves you have to measure from the valves seated position to the stem while the valve is installed. Since resurfacing the valve increases the installed height of the stem, the stem has to be cut down a bit. So there is some leway with how much the stem can be cut. But there is going to be a lot more to it than just finding a valve that looks like it is close. I would stick with OEM myself.
2014-07-13 16:50:36
#3
What have you read on Supertech Valves...
2014-07-13 20:45:51
#4
Ther really isn't much info on this. Especially if it's worth it or not in terms of cost vs gains. The vq35 valves are close. Same stem size, 0.6mm shorter though. And 37mm stock which can be cut down to say 35mm, and you'll have an oem valve. Just worried about that shorter stem.
2014-07-14 01:24:29
#5
A lot of breaking at the keeper relief. Or just dropping. Its not from personal experience or anything. They get a bad wrap in some places and hold up well in others. OEM valves drop, break and bend too. But all things being equal, size, I would stick with OEM strictly for the price.
2014-07-14 01:27:23
#6
I would have to look at the FSM to tell is .6 is within limits. Is there anything special about the vq35 valves that would make them superior to sr OEM? With the money spent in machining, it would cost as much as the super techs and still end up with the same quality valve as oem.
2014-07-14 02:25:03
#7
I've never had any sort of problems out of my Supertech valves... including the (frequent) occasional overrev (humvees are automatic, so my shifting practice is lacking lol).

Missed a 2-3 shift a couple times... running BC springs and oldschool S4s. I know the 240 guys are bashing them as being "made of gummy bear guts," but, is it really that widespread?

I also happened to pick mine up on a sale, about 4yrs ago, so price wasn't a concern then.
2014-07-14 06:09:49
#8
Originally Posted by ebinkerd
I would have to look at the FSM to tell is .6 is within limits. Is there anything special about the vq35 valves that would make them superior to sr OEM? With the money spent in machining, it would cost as much as the super techs and still end up with the same quality valve as oem.


No idea if they have anything special about them, i just like the fact that they're oem since the supertech has a bad rep, and there are no other options for us. Being 37mm means you can go as big as your chamber and bore allows too.

I can't find any dyno charts showing if larger valves results in any gain not he sr20ve, so not sure if i want to spend the money.
2014-07-14 12:53:41
#9
Many have said that bigger valves does not have much benefit until you go with a really big cam.
Last edited by squirlz on 2014-07-14 at 12-54-44.
2014-07-14 13:51:18
#10
Originally Posted by HJBarker
I've never had any sort of problems out of my Supertech valves... including the (frequent) occasional overrev (humvees are automatic, so my shifting practice is lacking lol).

Missed a 2-3 shift a couple times... running BC springs and oldschool S4s. I know the 240 guys are bashing them as being "made of gummy bear guts," but, is it really that widespread?

I also happened to pick mine up on a sale, about 4yrs ago, so price wasn't a concern then.


What do you mean gummi bear guts?
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