M20 Oversize valves

[matiasz]

You will need to do more than just fit a larger valve. The flow bench showed a loss in flow in usable areas by inserting a larger valve without additional work.

http://www.r3vlimited.com/board/show...&postcount=104

Yes, of course. Just wondering if the oversize valves was worth doing as well. :)

[ForcedFirebird]

Yeah, already got the Miller MAF that im going to run.
Thanks for the link, ill check out those threads.
I think im going to run stock seats and oversize intake then. Thanks again :)

You will need to do more than just fit a larger valve. The flow bench showed a loss in flow in usable areas by inserting a larger valve without additional work.

http://www.r3vlimited.com/board/showpost.php?p=4240085&postcount=104

[matiasz]

Is it worth it? Mmmh, if you are planing to use a maf or alpha/N instead of the stock "air flow meter" (i dont know the correct english word - but im sure you know what i mean) - i think: yes! I would go for VAC (but intake valves only are 270 $ - i asked last week) You can use the stock seat, but you need to open them a little.

About the oversize exhaust valves:
Even e21jps uses 36mm exhaust valves (stock size but not stock shape :D) in his 200 kw m20-beast (the reason is here: http://www.e30tech.com/forum/showpos...36&postcount=8 full: http://www.e30tech.com/forum/showthread.php?t=117701) I also think oversize exhaust valves are bad for torque (like a to much ported exhaut-side of the head). Interesting: He tooks 44mm (!) intake valves.

Yeah, already got the Miller MAF that im going to run.
Thanks for the link, ill check out those threads.
I think im going to run stock seats and oversize intake then. Thanks again :)

[Manu329is]

I am wondering this also. Im in progress of rebuilding my engine to 2,76l, my valves are fine but im thinking about doing 1mm oversize on the intake valves. Worth it? Should I do 1mm exhaust also?

Is it worth it? Mmmh, if you are planing to use a maf or alpha/N instead of the stock "air flow meter" (i dont know the correct english word - but im sure you know what i mean) - i think: yes! I would go for VAC (but intake valves only are 270 $ - i asked last week) You can use the stock seat, but you need to open them a little.

About the oversize exhaust valves:
Even e21jps uses 36mm exhaust valves (stock size but not stock shape :D) in his 200 kw m20-beast (the reason is here: http://www.e30tech.com/forum/showpos...36&postcount=8 full: http://www.e30tech.com/forum/showthread.php?t=117701) I also think oversize exhaust valves are bad for torque (like a to much ported exhaut-side of the head). Interesting: He tooks 44mm (!) intake valves.

[ForcedFirebird]

Wow! Talk about misrepresentation!

I have found this old forum post when I was looking for oversized valves for my m20b29. Strangely there are more providers in the US than in Germany ... :D

Although I have decided against oversized valves, but i want to show you pictures of my Schrick valves - it could well be interesting for one or the other. I also have a picture of a Dbilas valve, unfortunately the angle of the picture is bad and it´s hard to tell: but i think the Dbilas valve is not very flow optimized. The picture on the dbilas homepage doesnt show a m20 valve (that valve looks very nice!)The price is dbilas typically very high (40 € each) Schrick valves are € 27.50 each.

Intake (72 g):



Exhaust (63 g):



Dbilas:



Wrong picture in dbilas shop:

[matiasz]

do the seats have to be opened up any special way to use +1 valves?

I am wondering this also. Im in progress of rebuilding my engine to 2,76l, my valves are fine but im thinking about doing 1mm oversize on the intake valves. Worth it? Should I do 1mm exhaust also?

[Manu329is]

I have found this old forum post when I was looking for oversized valves for my m20b29. Strangely there are more providers in the US than in Germany ... :D

Although I have decided against oversized valves, but i want to show you pictures of my Schrick valves - it could well be interesting for one or the other. I also have a picture of a Dbilas valve, unfortunately the angle of the picture is bad and it´s hard to tell: but i think the Dbilas valve is not very flow optimized. The picture on the dbilas homepage doesnt show a m20 valve (that valve looks very nice!)The price is dbilas typically very high (40 € each) Schrick valves are € 27.50 each.

Intake (72 g):



Exhaust (63 g):



Dbilas:



Wrong picture in dbilas shop:

[SkiFree]

V Ireland Engineering has mostly Asian parts. Our E30's are German. Most Asian parts are compromised in manufacturing German aftermarket parts believe me I have been working on German cars for twenty five years plus. You get what you pay for 99 percent of the time.

IE: $276 for full set [NOT made in China, Tawain, etc]).

?

[digger]

i'd only be looking for oversized valves if overboring the block on a stroker so that the amount of shrouding between the valve and cylinder essentially doesnt change.

MM dont even use OS valves so what does that say for the size of stock valves? or their heads? Either stock are way too big as it is or MM are too small.

without some decent head work i dont think the OS valves would do much, the seat needs to be modified accordingly and you want a multi angle valve job.........where does it end?

[tinkwithanr]

Correct me if I'm wrong, but I don't think IE imports their parts. While there may be differences between the vendors, the cost of the parts along with the target consumer is also different.

If I'm just rebuilding a stock head to go on a stock bottom end, it makes sense to spend half the price for a valve that will match the performance of the other components in the build. Likewise, considering the amount of money I currently have in my stroker build, the $250 difference in price was minimal and gave me valves that would be a better match for the rest of my build.

[e30conv2]

Vac Motosports or Metric Mechanic is the way to go. Ireland Engineering has mostly Asian parts. Our E30's are German. Most Asian parts are compromised in manufacturing German aftermarket parts believe me I have been working on German cars for twenty five years plus. You get what you pay for 99 percent of the time.

[ROLLingKING]

VAC ftw

[tinkwithanr]

I got them roughly a year ago. I don't recall seeing a name on the stem when I looked them over, and they are currently installed so I can't check.

[digger]

They look like the Black Nitrided Supertechs

which are the same as the one i got from PPF (i.e have the backcut already done), but i am wondering if VAC now use the Manley ones instead becasue that is what i got late last year

[whodwho]

They look like the Black Nitrided Supertechs