Running a 4agze with no exhaust manifold, or stump type.

[kiwi4agze]

Hello
My question is a very simple one, Can I run the 4a head with a stump style exhaust manifold (3 to 3 4/8th inch) from the head ports without loosing to much scavenging efficiency for the cylinders or even run no exhaust manifold at all..

I don't care about noise, I need space and weight so trying to save on both.

I am worried it will loose to much this way, maybe I should run the stock manifold only.... Any ideas???

[touge_ae101]

just custom make some extractors that twist around each other and run horizontal with the engine. would be pretty sweet to look at.

[matt dunn]

We ran an old bluetop 4age with no exhaust manifold at all for a minute or so when we were fitting it to something years ago.

You would be amazed at how far the flames come out the ports when you give it a rev,
and the noise is insane.

As for performance, wouldn't have a clue as i'd never actually run one with no exhaust for those two reasons.
Couldn't be much worse than a crap exhaust design anyway.

[Mr Revhead]

I drove my s/c AW11 2-3 kays with nothing but the headers.
As Matt mentions the noise is insane. INSANE I tell you.

You will likely lose something down low and mid range at least. If it's noticeable there is only one way to tell.... But do be aware of the flame and heat range! Do it inside an engine bay and it will be on fire before the water temp is up!

[GTsedan]

Tractor anyone?

I've fired the v8 a few times with only the headers, reminds me of the speedway. Best not to do it too much, the neighbours don't enjoy it as much as I do.

Seriously though, I think the fire risk alone requires a short lot of headers (just dump it out the side). Plus the ol wives tale says that running without any manifold risks burning out the exhaust valves.

[tsoob]

post a video when you do this please

[kiwi4agze]

Heat is no issue, as the air at 15,000 feet is nice and cold! The air would keep the metal cool and the stock exhaust manifold is very heavy.

What i was thinking is a short 3- 3 4/8inch exhaust manifold exiting the cowl, or run no header and build an indent into the cowl to vent it starigh outside.

Noise is not an issue but been able to hear anything else would be good.

I am worried about the cyl scavanging and causing it to loose power.

what are the chances of burning the exhaust valves (that could be deadly!!!)

[Mr Revhead]

Oh so a light aircraft.
Stub exhausts will be fine then.
I'd have thought weight would be more of an issue.

I'd like to know how no pipes/stubs can burn valves

[GTsedan]

Oh so a light aircraft.

I'd like to know how no pipes/stubs can burn valves

A reduction in backpressure will cause the cylinder to bring more are into the engine than it would have been previously tuned for. Resulting in a lean condition and a burning of the valves (at least for carby cars).

Generally you don't need to worry about this with newer engines because of computer control and differences in how the exhaust ports are designed. I'm however unsure of how this will compare to your case of utilising mechanical injection.

Not much in the way of an exhaust is required, if it is going to be short just dont go crazy on the size of the primary collectors.

[Mr Revhead]

Sounds like an old car issue.

Does remind me of something though, where will you put your 02 sensor? Assuming it still be FI

[GTsedan]

There will be no O2 sensor, his intro post says that he will be incorporating a K-jetronic mechanical fuel injection system. Thats only why I mentioned the burning of the valves. Without the lambda feed back loop you have no idea if you are running at a rich/lean condition. However since this is for an aircraft where most of the work will be done at altitude and tuning on the ground I think a rich condition is likely, however that creates its own problems. I think a aircraft mechanic is better to give their opinion on this rather than me tbh

[kiwi4agze]

It is going to be Mechanical Fuel Injected, used the KE setup.

The ideas I had were:
1) Work out a way to keep the 4age injectors running at 90% duty cycle without using a computer...
2) Convert to mechanical fuel injection where the fuel injector is always on if the pressure is high enough.

While it will still use a Computer it has been chipped to run at 90% fuel flow rate under 2500rpm, 97-98% at above 2500rpm for take off and climbing.

The KE setup has no o2 sensor..

It will run mega rich at idle, but I was going to use the extra fuel to act as a coolant as well.

[Mr Revhead]

Sorry obviously missed the injection part!
I agree talking to someone who has dealt with tuning aero engines would be a good idea!
Wouldn't the CAA want to see that you have the enigne set up correct?

[kiwi4agze]

Under the Homebuilt/Experemential rules, I need to provide part numbers, drawings, testings etc for the engine and setup.

Aero people I find have great experence with aero engines not so good with car engine convert's.

[Mr Revhead]

Surely they can talk about what they do about mixture settings.
There will be quite a few who have done it to car engines as the Subaru flat 4 and VWs are popular

[kiwi4agze]

By using fuel asa coolant in the cyl with a basic water injection system it should limit the damage to the exhaust valves..

I want ti to run very rich so the engine has a greater chance of surviving take-off when at full throttle (100%) for up to 5 min.

[QikStarlie]

i wouldn't run it "very rich" especially if your using water injection. i forget the numbers now. but water has a massive cooling advantage, over running excessively rich. you only need a very small amount of water to replace the cooling a rich mixture gives.
i'd be worried about contaminating the oil running overly rich for long periods.

couple of points that maybe helpful.

*just rich of stoich (14.7 afr) is hottest burn. either side of this is cooler
*retarded timing will skyrocket egt's

[RS13]

Nice, subscribed. I'm quite keen to build my own as well once I get time and space! I only deal with the big jets so can't help.. however, I was sure I'd seen/heard of a 4AGE powered lightie, bit of google digging and it turns out I had, and he's even in Dunners!

http://www.homebuiltairplanes.com/forum ... s-d5a.html

That site also has a section dedicated to auto engine conversions..

http://www.homebuiltairplanes.com/forum ... iscussion/

Can I ask what airframe you're sticking this in?

[matt dunn]

i wouldn't run it "very rich" especially if your using water injection.

Very rich will also cause bore wash and wreck the engine.

And you say noise is no problem,
sure there may not be anyone around to annoy with it,
but it at the point where it actually hurts your own ears and I doubt you could put up with it for very long yourself.

[kiwi4agze]

Hi RS13.
He is a good mate of mine and put me on to the idea of the 4age/4agze.

I am putting it into a replica of the Fieseler Fi 156 Storch. Stall speed 20knots, top speed est 78 knots, cruising 70 knots.

If you are ever in Auckland, hit me up you are more then welcome to come learn a bit and photocopy some of my plans.

How do I insert photos? I finally completed my loom, from ford escort RS turbo (1986) KE jet mechanical fuel injection to fit a 4agze Toyota EFI engine!
If anyone wants i can write a tech article about it.

Edit: Stupid me found out how...
http://imageshack.us/photo/my-images/69 ... 1170d.jpg/
Loom completed, if anyone wants a FAQ please ask.
http://imageshack.us/photo/my-images/17 ... 011167.jpg
loom stored away safe
http://imageshack.us/photo/my-images/84 ... 11168.jpg/
Did I tell anyone I hate wiring
http://imageshack.us/photo/my-images/33 ... 11171.jpg/
My $1 intercooler!!!