4age valve upgrade options

[myne]

Building up a head for the future use on a (hopefully) twincharge engine.

What are the reasons not to use the 30.5mm inlet valves on the exhaust side?
Say I chucked 8 into a lathe and ground them down to a different size, would that matter?

What valve options are there?
I'd like to improve overall airflow with a fairly modest cam, and a fair bit of boost.
I was thinking something like 8-8.5mm lift and 250-260*

[nick.parker]

Hi Myne,

Quoting one of my post from a while ago, that nobody really answered at that time....

The exhaust port on my 4AGZE is 30mm, and the exhaust valves are 25mm.
The area of 2 x 25mm valves is equivalent to 35mm circle but is this relevant? The actual open area, converted to an equivalent diameter would be SQRT( 25dia x 8mm lift) = equivalent to a 28mm hole, so two of these = 39.6mm hole. Now obviously this is completely ignorant of any fluid dynamics but are there calculations useful? Does this mean my exhaust port is the limitting factor? (assuming my engine had enough air going through it in the first place)

The 30.5mm valves would be heavier (but better with exotic material maybe) , requiring heavier springs = more wear. Maybe there would be less 'meat' to heatsink the spark plug area into head, maybe it would be weaker - I guess you could ceramic coat. Might be harder for air to get past the valves if they get too close to the cylinder wall (is that called shrouding?) Would there be enough meat in the head (before water jacket) to bore the area behind the valve out to 30mm also?

FYI : The formula atlantic valves are 27.5mm (though I have seen you can get 28mm).

Cheers, Nick

[allencr]

What are the reasons not to use the 30.5mm inlet valves on the exhaust side?

Just one reason, or maybe 8!! They'll melt!
They may look the same, but the material is pretty different.

[30psi 4agte]

Allencr you hit the valve on the head with that one!!
Exhaust valves are generally a different material to cope with the heat . some valves are sodium filled to cope with the extreme heat.

To gain air flow there are a few tricks around . one of them is to machine out 90% of the seat and use the last 10% to seal the valve.Effectively it is like having bigger valves fitted.

You can gain about 1-1.5mm by doing this.

[nick.parker]

Hi,
This is some info I found in the past on MR2OC (I think). Its might be a possibility for oversized valves. The 3SGTE intake valves and 3SFE exhaust valves would maybe need the stems shortened.

Cheers, Nick

4age Intake valve specs
Head Diameter = 1.201in. --- 30.5mm
Stem Diameter = 0.236in. --- 06.0mm
Overall Length = 3.925in. --- 99.7mm

4age Exhaust valve specs
Head Diameter = 1.004in. --- 25.5mm
Stem Diameter = 0.236in. --- 06.0mm
Overall Length = 3.925in. --- 99.7mm

3sgte Intake valve specs
Head Diameter = 1.319in. --- 33.5mm
Stem Diameter = 0.236in. --- 06.0mm
Overall Length = 3.957in. --- 100.5mm

3sfe Exhaust valve specs
Head Diameter = 1.062in. --- 27.0mm
Stem Diameter = 0.235in. --- 06.0mm
Overall Length = 3.954in. --- 100.4mm

[fixeruperer]

if your prepared to build a donk motor i dont know why you would use other factory model parts, buy stronger and hardend aftermarket parts there are bigger valves and springs from say FERREA
the more you cut away at your head the more you make it weaker between the valve seats and to cut and fit new startlite/nikkle seats is expensive but worth it.
with the twincharging the only good kits i have seen is from hks/blits , ive seen many attempts that look ugly and are inefficeint, the main problem people have is the change of airflow from s/c to turbo you can try blowing supercharger threw turbo but the s/c would have to push some air in higher revs to keep up with turbo, with twincharging its all in that valve if you can get a big enuf "Y" shape valve your larfing.
and for cams youd want atleast 264/272 but everyone's ways are differant.

[myne]

I actually compared a 3sfe valve today. It was 1mm longer as you know, and really couldnt be shortened (the collet is the same distance from the top on both) So I'm not sure how much of a pain it'd be.

http://www.dprracing.com/prod&serv/H...oyotaheads.htm

Anyone know the length/stem size of 1zzfe valves?

[Dimitri]

peoplehave used 3sfe/5sfebefore. aswell as 7mge. the 3s ones have a nicer shape onthe back.

[CHB]

so any one has any example of a successfuly upgrade using 3S (FE, GE or what ever) valves? i have heard that only early gen 3SGE valve suitable for for 4AGE 16V head but not the 3SGTE valve. even so with 3SGE valve, the distance between valve during cam overlap will be extremely close to each other. thats what makes them step back from the experiments..