4G63 2mm oversize valves?

[Dasithkg]

hi all,,,

just saw some supertec valves for 4G63, 2mm oversize... on ebay...

isnt that too big? what kind of gains could there be with them?

cheers
Dasith

 

[BMGTZ]

hi all,,,

just saw some supertec valves for 4G63, 2mm oversize... on ebay...

isnt that too big? what kind of gains could there be with them?

cheers
Dasith

I have 1mm oversize in one of my engines....along with some porting and shaved the head face. the difference is quite noticeable....faster spool and more power all the way through the rev range when compared to another car with similar spec

my 2c is to go bigger on the exhaust 2mm and use the 1mm on the inlet because you can always turn the boost up to shove some more air in.

 

[Dasithkg]

awright.... thanx mate....

just curious if anyone actualy had them in here...

 

[JC evo1]

I would only do oversize valves if building a stroker or dont mind sacraficing midrange for top end.

 

[Dasithkg]

I would only do oversize valves if building a stroker or dont mind sacraficing midrange for top end.

funnily enough , thats exactly what im planning.

 

[DOUGMO]

2mm is overkill, the ports cant flow enough

 

[Lister]

I had these fitted into the head of my 2.3, along with porting. I have 272 cams, and a td06-20g. I fitted them to the intake side, and fitted 1mm o/s on the exhaust.
I do lose a tad down low, that being said though. Midrange, and top end is phenomenal.

 

[JayRome]

i'm on 1mm over sized int/exh and i haven't lost any down low, but have gained some crazy topend

 

[CLuTZ]

So you guys only did over sized valves as a mod and measured the difference from before? :lol:


What i'd do is talk to the person who is building your engine and ask them what they want as far as parts go

 

[Lister]

Not quite as a mod on its own. When I built my stroker, I asked if there would be benefits from fitting o/s valves, and porting/polishing. Answer was yes especially on a 2.3. Now as I was supplying parts I may have cocked up my order slightly and ordered the 2mm o/s intake ones instead of the 1mm. That being said when they turned up my engine builder called me, we chatted about the implications of using said part. He was confident with everything else, combined they would work well.

 

[BMGTZ]

So you guys only did over sized valves as a mod and measured the difference from before? :lol:


What i'd do is talk to the person who is building your engine and ask them what they want as far as parts go

no not as a mod on its own with comparison of before and after dyno checks. however I can say when compared to one of the other three cars I had at the time which all have 4g63 engines. this car with 1mm os intake and exhaust has noticeably faster spool and is more responsive at low revs. whether that is due to increased compression or porting can be debated........but I believe these valves are contributing because one of the cars has a six bolt engine and that has much larger ports as standard.....yes the butterfly for the ports is connected as well on the 6 bolt

 

[GVR40]

6 bolt heads have bigger inlet ports, however the 7 bolt head design is better due to the angle or the ports, it is more direct and flows more air at a higher velocity. so you can't compare a 6 bolt head and 7 bolt head with different sized valves in it, it would be like comparing apples with oranges. both are good in their own rights.

 

[BMGTZ]

6 bolt heads have bigger inlet ports, however the 7 bolt head design is better due to the angle or the ports, it is more direct and flows more air at a higher velocity. so you can't compare a 6 bolt head and 7 bolt head with different sized valves in it, it would be like comparing apples with oranges. both are good in their own rights.

three cars and one is a six bolt.....2 are seven bolt one of those has bigger valves

 

[EVO-00X]

IMO, if you're machining the stock valve seats I'd only go 1mm oversize. If you're dropping all the valve seats out for new oversize valve seats then IMO go 2mm, however its not really required for anything other than a dedicated race car where you're scrounging for every extra spare hp you can get and money is no object. Reason being is that it can get quite painstaking, risky and expensive dropping out the existing valve seats and have milling and installation done for 16 x brand new 2mm oversize seats to suit your 2mm oversize valves. For the 4G63 head with 4 valves per cylinder, it really needs to be heated up and cooled down again when fitting new 2mm oversize seats. The extra meat in the 2mm oversize seats provides strength ad longevity because you didnt have to machine the stockies out.