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Author Topic: Let me introduce my maztra  (Read 48905 times)
Anders Dinsen
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« Reply #75 on: November 16, 2008, 03:05:20 pm »

Your construction looks extremely good. It would be a pity to go back to the carb (I'm sure you agree Wink ).

I don't understand why a dcoe throttlebody will work, and what i made won't.

I think the spray pattern of your injectors could be the source of the problem. A carburettor emulsifies fuel in the air, and if the manifold is reasonably smooth on the inside, the fuel will not condensate on the manifold walls unless the manifold is very cold. Especially with this design, where the manifold has a long horisontal section: All the fuel that condensates will sooner or later end in the engine anyway. An injector does not emulsify the fuel in the air in the same way as the carburettor, but makes a fine spray of fuel. On production piston engines, the fuel is sprayed on the back of the closed valve to cool it down, and the fuel "mist" is later sucked into the engine when the valve opens. Spraying on the hot valve also prevents condensation. It's like a pair of glasses - moisture condensates on cold glasses, not on hot!

It looks like you have some relatively long stems on the injector bosses. If the spray pattern of the injector is optimised against a large diameter inlet engine, it could be quite wide and most of the fuel may end up being sprayed directly on the walls of the bosses. You could go to a scrap yard and try to find some injectors from a smal engine with multipoint injection - e.g. a Fiat Punto 75 (I used to have one Wink ) and fit them instead. I know they will be too small for full power operation, but if you can make it idle well, then it may work for you. Alternatively you could try shortening the stems on the bosses so the full spray goes into the manifold.

Have you tried firering the injectors on a piece of paper to see the pattern? I've read one source recommending that to check the injector and to verify that several (used injectors) are compatible.

- Anders
« Last Edit: November 16, 2008, 03:10:39 pm by Anders Dinsen » Logged

'82 Murena 2.2 prep 142
'01 Grand Espace 24v
'08 Smart Fortwo 0,8 cdi
Bart_Maztra
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« Reply #76 on: November 16, 2008, 03:56:35 pm »

The injectionsystem is now sitting in a corner for a few months. Haven't give it any attention since then.

Don't think condensating is the problem. Because:
1 the manifold directly above the exhaust manifold, so it will warm up.
2 Simular set-ups with a proper dcoe throttly body + injectors are working. With the injectors further away than i have.

Lenght of the stem: The injector boss is designed for this purpose, so i assume the stem is allright!

But thinking of it:  There is a 13mm hole in the manifold where the boss is sitting against. So maybe the fuel is spraying against the inside of this hole? Maybe i have to enlarge the hole?  Have to check.

Another thought:
As i have 1 throttle body, the two manifold runners are connected together. When 1 cilinder is doing the intake, it is effecting the air in the other runner.  With a proper dcoe throttle body the two runners become individual.  That's worth an experiment.  i still have a dcoe style carburettor somewhere. If i take out the venturies, i can use it as athrottle body! See if that makes a difference!

And it's a good idea to check the spraying pattern and the cc/min.
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Anders Dinsen
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« Reply #77 on: November 16, 2008, 07:10:15 pm »

The injectionsystem is now sitting in a corner for a few months. Haven't give it any attention since then.

That's quite understandible...

Quote
Don't think condensating is the problem. Because:
1 the manifold directly above the exhaust manifold, so it will warm up.
2 Simular set-ups with a proper dcoe throttly body + injectors are working. With the injectors further away than i have.

There could be a few differences which I think could be interesting to look into... For example, on a throttle body, the injector is angled downwards. With this manifold, the injector will probably be looking into a wide and relatively deep well through the corner of the inlet runner. On your setup, the injector is probably looking down into a relatively narrow tube. The amount of fuel which it is spraying on the walls won't be abe to find its way into the engine when it's idling and air flow is small.

Regarding the manifold heating, don't forget that while the exhaust is heating it, the inlet air will be cooling it, so it will level up to a certain point. Water heated manifolds are generally considered to be better.

Quote
Lenght of the stem: The injector boss is designed for this purpose, so i assume the stem is allright!

Agree.

Quote
But thinking of it:  There is a 13mm hole in the manifold where the boss is sitting against. So maybe the fuel is spraying against the inside of this hole? Maybe i have to enlarge the hole?  Have to check.

Yes that could be blocking the spray.

Quote
Another thought:
As i have 1 throttle body, the two manifold runners are connected together. When 1 cilinder is doing the intake, it is effecting the air in the other runner.  With a proper dcoe throttle body the two runners become individual.  That's worth an experiment.  i still have a dcoe style carburettor somewhere. If i take out the venturies, i can use it as athrottle body! See if that makes a difference!

Yes that woule be easy. How many inlets do you have on your engine? Three or four? If the two middle runners are connected, then you have it all joined together anyway, even with a double-carb.

Quote
And it's a good idea to check the spraying pattern and the cc/min.

Especially pattern and how long they spray the fuel as it will tell you something about where the fuel is during idle.

- Anders
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'82 Murena 2.2 prep 142
'01 Grand Espace 24v
'08 Smart Fortwo 0,8 cdi
krede
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« Reply #78 on: November 16, 2008, 08:31:19 pm »

Like you suggest yourself, I ,too, would find a a twin dcoe throttlebody. (how about some from a motorcycle?.. you ought to be able to find some pretty cheap)

Failing that... how about fitting two smaller injectors in each pipe?? perhaps the big ones are simply not able to get the fuel mixed right at such low air velocities?

I think the way you mount the injectors seems sound enough... but then again perhaps not .... placing them in a "sharp bend" might be wrong.
The best way of fitting injectors is at an angle not more then 30 degrees, and aimed towards the middle of the inlet valve. (according to the wolf 3D instruction manual). But that might not be possible.

But first.. I would try the twin throttle plate set up.. and some other injectors.
How about fabricating four separate inlet runners?.. each with its own tb?
That would also sound AWESOME! especially at such high revs. Smiley 
« Last Edit: November 16, 2008, 08:56:39 pm by krede » Logged
Bart_Maztra
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« Reply #79 on: November 16, 2008, 08:55:17 pm »

Just saw some throttle bodies from a bmw R1100 on ebay. Those are 45mm. Interesting.....

But first try the carb as throttle body, and test the way the injectors spray.

The original manifold is heated by coolant, and the dcoe manifold isn't.  Before i started all this intake effort, i blocked off the coolant ports from the engine to the manifold. That way i could easily change the manifold without draining the coolant.
Last week i undo this blockage. The original carb would stay on for a longer period and with winter coming, heated manifold would be better. But that also means that if i want to experiment with the other intake, i have to drain the coolant.

To be thruthfull, i also have plans for the original carb. In America there are some guys who can modifie the carb. They change about anything on the carb and the result is outstanding! It has got my attention.
http://www.sterlingmetalworks.com/sterling.htm

Since the beginning of wankelness, my carb is not level. That is sorted now!  It has a aluminium spacer in a wedge shape.





If i am wise, i forget all this and focus on my exhaust.  Even with the carb level, i still don't have the amount of power which i had in the mazda.  Must be the exhaust. So "Bart, be wise and sort that first!"
« Last Edit: November 16, 2008, 08:58:05 pm by Bart_Maztra » Logged

krede
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« Reply #80 on: November 16, 2008, 09:06:17 pm »

A carb might be cool as well... but I think injection is much more exciting.. Smiley
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Anders Dinsen
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« Reply #81 on: November 16, 2008, 11:00:00 pm »


If i am wise, i forget all this and focus on my exhaust.  Even with the carb level, i still don't have the amount of power which i had in the mazda.  Must be the exhaust. So "Bart, be wise and sort that first!"

Your engine was longitudal before and is now transversally mounted. Have you rotated the carburettor so it's facing the same way as before with regards to direction of travel? Most carburettors are quite critical with this as float level changes during acceleration if it's mounted the wrong way 'round. DCOE's don't, but they are the exception.

The manifold design is really special.

Carb and your spacer look very good.

- Anders
« Last Edit: November 17, 2008, 06:59:51 am by Anders Dinsen » Logged

'82 Murena 2.2 prep 142
'01 Grand Espace 24v
'08 Smart Fortwo 0,8 cdi
Bart_Maztra
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« Reply #82 on: November 22, 2008, 09:37:26 pm »

Today the dutch RX-7 club had a meeting. They visited a custom exhaust manufacturer. Not just a manufacturer, but EPS, which is THE custom exhaust specialist from Holland and abroad.
Allthough i am not a member of the RX-7 club anymore, i was welkom to join this meeting.

A day well spent!  Learned a lot!  This was the big opportunity to ask the exhaust experts thousands of questions. They were very patience and enthusiast to help me forward with how to make a complete new exhaust system.

The plan is to make the flange which bolts to the engine from mild steel. Stainless is not suitable as flange.  The header will be made of 1 3/4" (44,5mm) stainless steel 304, wall thinknes 2mm.  I will be made of seperate bends and pipes welded together.  The bends will have the same diameter, as my current bends are narrower.  The shape will be roughly the same as the current one.  There will be two simular mufflers from borla pro xs.



Gonna make it all by myself. Well, that's the plan. I will put this plan on top of the pile with all the other plans. (brake lines, carburettor, injection, vw beetle, mercedes c250, yamaha tdm, fix thousand things in my house, ...)

This is the current exhaust




The murena muffler is replaced by the mazda muffler.

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Bart_Maztra
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« Reply #83 on: February 26, 2009, 09:04:11 pm »

Just made a start making the new manifold.
Bought some 50,8x2mm stainless pipe. (i could only buy one complete section of 6 meter....) And got some 90' elbows and two mufflers.  The mufflers were very cheap from kts.de for 66 euro each. These mufflers normaly costs 90 dollar in the usa or 130 euro here localy.

The exhaust flange will be lasercut from 12 or 15mm mild steel. I expect to get these in a week.

For now i use a temporarely flange so i can start "trail-and-error design"



Started from the flange a 40' elbow goes up and ten with a 90' elbow diagonal down. Then with a 26'elbow horizontal, and straight around the corner. Just after the corner the 2 pipes joined, and then around the corner to the muffler.  The second muffler will fit directly on the first one. I hope i can fit these mufflers this way under the car.
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krede
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« Reply #84 on: February 26, 2009, 09:24:38 pm »

I love reading about this project of yours...
What did you decide upon for fuel delivery?.. did you drop the injection all together? or are you giving it another chance?.... personally I think it would be a shame to go back to a carburettor on such a radical modification.. Smiley
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Bart_Maztra
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« Reply #85 on: February 26, 2009, 09:42:30 pm »

Don't know yet. Fuel injection lost my interest for now. Maybe LPG injection???



Just stick to my carb for now Roll Eyes
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krede
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« Reply #86 on: February 26, 2009, 09:47:57 pm »

WOOOW! Smiley
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Bart_Maztra
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« Reply #87 on: March 03, 2009, 10:28:01 pm »

Little progress so far.



The runners must be 60cm each.  The point where they join is in the bend.



The second runner will be very bendy to get the same lenght. 

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Bart_Maztra
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« Reply #88 on: March 05, 2009, 08:45:17 pm »

bit more progress

The way the second runner runs is changed. As it is now, it fits in the engine bay. Enough clearance around the pipes.
Only i run out of 90'bends. Have to order some more.....



Today i received the flange, lasercut in 12mm steel. 2 off actualy Roll Eyes. In case i messed one up.....
19 euro each, not bad.



Please ignore the piece of wood.



Next thing is to tack weld the pipes to the new flange, and see if i still can get it in position. It is already difficult to get the temporarly thin flange in position, so the real flange will be quite challenging....

Also have to think what to do with the movement of the manifold when the engine moves.  Have to make a flexibel joint somewhere.
 
« Last Edit: March 05, 2009, 09:30:26 pm by Bart_Maztra » Logged

Bart_Maztra
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« Reply #89 on: March 14, 2009, 08:39:04 pm »

Who says that rotary engines use a lot of oil?
On the contrary! The oil level is raising.

This week i checked the oil level, and it was a lot above maximum.
There should be about 4 liters oil in the sump. I drained the oil and it was 5,5 liter Shocked

Noticed no strange things on the oil. No signs of water.
It only can be the two stroke oil entering the sump.

During the convertion i modified the oil pump, which is adding some oil in the intake, like a two stroke engine.  Originaly it was pumping oil from the sump, but i modified it so it is using two stroke oil from a separate tank.  I blocked the pasage to the sump, and made a new entrypoint.  Think the blockage disapeared, so the two stroke oil is entering the sump.  Embarrassed

Otherwide i don't have a clou what is happening.

The oil pump is well hidden behind engine mounts and drive shaft.  Big job to service the pump.  For the time being i drained the two stroke oil tank, and disconnected the oil lines from the intake.  Just poured some two-stroke oil directly in the fuel tank.

Mounted the old exhaust manifold, fixed a coolant leak, add some water-wetter stuff (very curious how that works) an went for a spin.  Today it was a beautiful day, and it was a real joy to drive.  Tommorow there is a local classic car show, and i am invited to show my car Smiley
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