valve angles on 'fe' heads ??

[ed]

as in title? anyone?

cheers
ed

[horse]

GE heads, 45 degrees
FE heads 22 Degrees, well thats from what i know about the 3s family

hope that helps

[Steve-AE86]

is true.

ps. 'is true' isn't 10 characters, so therefore not long enough of a reply, so i typed this garbage as well

[oldcorollas]

is there a correlation between the angle between port and valve? or doe sthat vary between different heads, as opposed to between F and G heads?

[oldcorollas]

posted by TOYCRASH by PM whilst waiting or approval (hint hint )

For A-series engine, there is two different port angles.
if i remember correctly they were pre and after -92

-92 and after 4A-FE has much more vertical ports than older versions.
This is the after -92 head.
And as you can see, it does not have injector places at head.

Older version has injectors at head, adn newer version has then at intake manifold.

[CrUZida]

The 45/22 is no longer 100% true

The 1ZZFE and 2ZZGE do not share this.
The 1ZZFE even has 2 separate cam gears.

1ZZFE = 33.1deg
2ZZFE = 43deg

[Jonny Rochester]

The 2T-G does not have 45 degree valves either. I think I said they were 45 degrees once when explaining it to my mum, but last time I looked it was a different angle. A bit less.

[myne]

Out of intrest, anyone care to explain what bearing on performance the angle of valves has?
Is it combustion chamber shape, flow characteristics, port angle, what?

[takai]

ed: the valve to port angle also varies per engine even after 92. The 4AFEs have a different angle to the 1GFE and 1UZFE. But those measurements above are pretty much bang on the money if you allow for a variance of a degree or so.

myne: it affects the lamina (with or without R these days?) flow into the head, less bends == more direct flow. Infact, if you want to have a good read about it, then go PM Neil Roshier somewhere (PF prob) and get backissues of Race mag 1-3. Or come pester me for my copies (no greasy mitts). Has a brilliant article series regarding head flow

[Jonny Rochester]

Its a combination of a few things. For best power at high rpm, the head just has to flow lots of air/fuel. To flow alot you usually need the biggest valves you can fit, and fairly large ports that don't have too many bends and curves to them. The old engines built for high rpm (2TG/18RG) just have 2 big valves. And it so happens when you try and fit 2 big valves in there you end up with a crossflow head. The large angle on the valves allows for a smaller angle of the port in the head, and also allows for larger diameter valves. I think the 2T-G and 2T head is similar, 2T has smaller valves, similar angles.

But this design is not so good for low rpm. Because with a large valve/port the airflow is too slow which is not good for making carbs work. The result is poor ecconomy and poor torque at low speeds.

To fix this generic engines just had very small carbies to mix the fuel better.(2T-C) Other engines had both valves on one side with smallish valves, and a squish area designed in the chamber.

Getting back to valve angle, I don't think it has much bearing on performance at all. Its more to do with the complete system used. The old 4A-GE had larger valve angle to early 4A-FE, but why? It wasn't realy needed. The 4A-GE was better mostly because it had bigger valves, more lift, slightly more cam duration, more compression etc.

The 20valve and late 7A-FE has a narrower valve angle, but the intake port is also angled up to match...

[takai]

Yes, but the main reason (according to the 2ZZ docs) for narrowing the valve angle was to produce a better squish area, and higher air speed into the cylinder. This allowed for a more aggressive combustion chamber to be created.

[Ben Wilson]

The old 4A-GE had larger valve angle to early 4A-FE, but why? It wasn't realy needed. The 4A-GE was better mostly because it had bigger valves, more lift, slightly more cam duration, more compression etc.

It's all a balancing act, higher valve angles allow bigger valves as you said, it also makes it easier to get the ports coming in from behind the valves (something Toyota stuffed in the 4AG).

Shallower valve angles means the ports have to be closer to vertical to get a decent entry (a big packaging problem in modern engine bays) and the valves obviously have to be smaller, but they get can much better combustion chamber shapes.

[takai]

Shallower valve angles means the ports have to be closer to vertical to get a decent entry (a big packaging problem in modern engine bays) and the valves obviously have to be smaller, but they get can much better combustion chamber shapes.

Except in the VVTi 1UZ, which seems to have a very good runner/port angle.

[myne]

As I suspected, it's more the practicality of the inlet runners and other various trade-offs than any specific limitations.
Does this then mean that (assuming the inlet runners were direct) it could be possible to fit "G-profile" cams to an "F" and come close to approximating the same performance?

I'm interested on a purely intelllectual level.
The F engines seem to be shunned on the smaller scale but the mighty 1uzfe is loved. I've seen people comment that turboing a 4af is pointless, and that they should get a 4age first.
I know that has to be just a mindless opinion since you can make a workable turbo package for anything, but would the "F" still end up being the huge limitation that is implied? Would it make any difference whatsoever? Or would it just require accepting the limitation and working to a different rpm range?

At the end of the day it's still a 16v 4A, the G and F max potential shouldnt be that far apart should it?

[Nim]

According to what I've read, a lot of it on Bill Shirwoods site, the reason a wide angle is better is simply so you have less of a curve on the runners and to make the head design simpler. But a nice close angle head makes a better combustion chamber. A flatter pent roof on a cylender chamber means less dome on the piston which is a good thing.

As a note, the SR20DET has a close angle head. It actualy has lash adjusters so it can run 2 cam gears and still have the narrow angle. I BELEIVE (and anyone feel free to correct me if I'm wrong) that the close angle head is actualy why it's prone to detonation.

Another issue with a close angle head is that to reduce the curve of the runners the engine has to be very tall, making it hard to fit in an engine bay. Apparently there is one version of the 5S-FE which is pretty good for performance, but requires a bit of work to get it rev well as it was never really designed for high RPM.