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Thread: Advice available for all Mazda Eunos 800m owners

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    Default Advice available for all Mazda Eunos 800m owners

    If you have a Mazda Eunos 800m vehicle and it has problems ,I am quiet happy to answer all your questions



Look Here ->
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    Yeah ive got a problem, explain the supercharged miller cycle engine they use, why they used it and what are the benefits on a road car?

    What ive yet to comprehend is why leave the intake valve open and the bottom of the compression stroke to reduce power loss and yet the pressure of the supercharged intake is pushing against the piston any way and it still builds the same total static compression as a normal engine at top dead center.

    Is it to reduce piston ring drag which increases as compression builds?

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    The Miller-cycle engine, the delayed intake-valve closing means that the crankshaft travels through nearly 70 degrees of rotation before the intake valve closes, which moves the throw of the crankshaft's rod journal out of alignment with the other two. This creates a lever arm, that in turn means the crankshaft has a greater mechanical advantage when compressing the intake charge. allowing the crankshaft to push the piston back up freely, without the extra work of compressing the fresh air. this shorter compression stroke increases the engine's expansion ratio. After combustion takes place at the top of the compression stroke, the expanding gases push the piston all the way down to the bottom of its stroke, allowing the air/fuel charge to burn thoroughly with little wasted energy. That the Miller-cycle engine creates power for the duration of its full stroke, but only has to spend energy squeezing the intake charge for four-fifths of its compression stroke, results in enormous torque for a given displacement. 2.3 liters, while producing the same power as a theoretical 3.3-liter V-6 using the Otto cycle. The smaller displacement also results in 25% less internal friction than the larger engine because of its smaller pistons and valves and this allows the engine to spin much more freely and rev much faster than a typical Otto-cycle engine.

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    Nah its still lost me.....

    Holding the intake valve open so long while the piston is in the compression mode from the start of the compression stroke is what has me stumped.

    Holding the intake valve open while the piston does into compression mode for so long usually means that some of the air fuel mix will be pushed back out the intake system reducing the amount of air fuel mix to burn and also above all reduce the engines total static compression ratio.

    As we all know air and fuel and compression build power, drop compression, drop power.

    The other thing is the air flow entering a cylinder is heading one way, that is towards the cylinder itself, a valve may stop the flow, however it sounds like the air flow is one way, then a little back out again, then the valve closes and stops.

    In everything ive learnt about engine theory it probably the worst way to make power......im still missing some thing to answer the puzzle in my mind.

    Could it be with the supercharger pressure replacing the lost compression in the stroke while the intake is open longer that it makes its loss of static compression.

    If so then the valve would be open with no pressurized boost entering, therefore the boost pressure would have to be nill not to push against the piston which is trying to climb.

    Im definitely missing something....could be my marbles.....i might Google it tomorrow night if i get time, this one has me on a mind bender.

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    do you have one ????

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    No but im into my engines, and if i dont understand how something works in detail i dont take it lightly.

    If i get some free time tonight ill see how Google goes.
    Last edited by Godzilla; 25-06-13 at 09:16 PM.

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    The key to this theory is that more energy is lost in pumping effort during the first (x) degrees of crank rotation than is gained by compressing that additional (x) amount and burning it.

    To put this into context, you may lose, say 10kW of power as a result of lower combustion pressure, but you've saved 20kW by reducing the pumping effort. The net gain of 10kW is what proves this theory. This is how they reduce the size of the engine for the same output.

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    Could this be also achieved by selecting a custom made cam grind to replicate the effect in a normal engine?

    Your post as the clearest explanation of the theory so far.....thank you.

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    Mechanic's Post # 7 is A good Explanation to me.. Makes Sense.. Less Effort required once Crank has turned that bit extra as Opposed to Compressing when crank is at switching direction point...

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    Default Loss of power when Eunos 800M Traction Control System light comes up

    Quote Originally Posted by chrismurphy View Post
    If you have a Mazda Eunos 800m vehicle and it has problems ,I am quiet happy to answer all your questions
    Hi Chris

    My name is Lawrie Miller and I have a 1994 Eunos 800M car which has been marvellous and so reliable! About one year after I bought it new, it lost power on a hill and the Traction Control System light came on. When I turned the engine off and restarted it, the TCS light went off and normal power was resumed. This was fixed by the dealer under warranty and they said that a small tube had come away from the auto transmission.
    The Eunos 800M had not skipped a beat until about one year ago (19 years later) when I was driving up a steep mountain pass and the TCS light came on and the engine started hunting with very little power. I turned it of and restarted and we got home (900 kms) without any further problem.
    Just recently, the TCS light has started coming on, usually on a hill, and the engine loses power and I have to turn it off to get us going again.
    Is this a simple problem or is it much more serious?
    The Eunos has only done 220,000 kms in that time and is in very good condition otherwise. No problems with the supercharger, etc., in that time. Many thanks. Lawrie

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    Sounds like that tube has let go again, Lawrie. (I am not a mechanic, BTW)

    @ Goszilla could it possibly be that by leaving the inlet open for longer allows less power to be required for the piston to reach the top of the compression cycle. The "blowback" of fuel/air mix because of the open valve may be mitigated by the pressure of the incoming mix made by the Supercharger (or Turbo as the case may be). If my understanding is correct, forced induction must, by its description, force fuel/air in at pressure which may be offset owing to the extended valve opening.

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    most racing engines would not be closing the inlet valve until the same time the miller motors close there inlet valve..60 to 80 degrees after bottom centre and they are not blown

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    Quote Originally Posted by LawrieM View Post
    Hi Chris

    My name is Lawrie Miller and I have a 1994 Eunos 800M car which has been marvellous and so reliable! About one year after I bought it new, it lost power on a hill and the Traction Control System light came on. When I turned the engine off and restarted it, the TCS light went off and normal power was resumed. This was fixed by the dealer under warranty and they said that a small tube had come away from the auto transmission.
    The Eunos 800M had not skipped a beat until about one year ago (19 years later) when I was driving up a steep mountain pass and the TCS light came on and the engine started hunting with very little power. I turned it of and restarted and we got home (900 kms) without any further problem.
    Just recently, the TCS light has started coming on, usually on a hill, and the engine loses power and I have to turn it off to get us going again.
    Is this a simple problem or is it much more serious?
    The Eunos has only done 220,000 kms in that time and is in very good condition otherwise. No problems with the supercharger, etc., in that time. Many thanks. Lawrie
    The problem you are ecperiencing is due to a vaccum issue .reply and i can walk you through a fix

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    Red face Eunos 800M Power Problem

    Quote Originally Posted by chrismurphy View Post
    The problem you are ecperiencing is due to a vaccum issue .reply and i can walk you through a fix
    Hi Chris

    Many thanks for your quick response. Anything you can do to help me would be appreciated.
    As I said in my question to you, my Eunos 800M is still in very good condition and I would like to keep it on the road as long as it stays reliable.

    Warm regards

    Lawrie

    PS I have just turned 80 and am still interested in working on cars as I have done for more than sixty years!

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    Quote Originally Posted by LawrieM View Post
    Hi Chris

    Many thanks for your quick response. Anything you can do to help me would be appreciated.
    As I said in my question to you, my Eunos 800M is still in very good condition and I would like to keep it on the road as long as it stays reliable.

    Warm regards

    Lawrie

    PS I have just turned 80 and am still interested in working on cars as I have done for more than sixty years!
    Ok i need to take some pictures to show you where to look for the faults, sorry i have taken so long to reply ,but been too busy lately.
    will take some pics today and post soon. dont give up on these cars . your fault should be easy to fix
    Just to confirm the car goes into limp mode with the TDS light coming on and the car will not rev over approx 2500 rpm . Also what year is yours

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    Default Loss of Power of Eunos 800M

    Quote Originally Posted by chrismurphy View Post
    Ok i need to take some pictures to show you where to look for the faults, sorry i have taken so long to reply ,but been too busy lately.
    will take some pics today and post soon. dont give up on these cars . your fault should be easy to fix
    Just to confirm the car goes into limp mode with the TDS light coming on and the car will not rev over approx 2500 rpm . Also what year is yours
    Hi Chris
    Many thanks for your reply. It is truly appreciated. There is no problem with any delay because the Eunos is still going well since last weekend.
    When climbing a hill and the TCS light comes on, the motor loses power and then it comes back, loses power again, comes back on, in a series of jerks, and so on. It jerks its way uncomfortably up the hill but it is OK when on reasonably flat roads.
    When the motor is stopped, by turning it off, and then restarted, the TCS light goes off and the motor resumes normal operation and power.
    I have noticed that, on a couple of occasions when this happened recently and restarted immediately, the power steering assist was not as normal which makes me think that the speed power assist is also affected. But this also comes right when the motor is re-started again.
    My Eunos is a 1994 model and is still in top condition.
    Warm regards
    Lawrie

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    see this link for photos and manuals for your milly



    Look at the photos section ,I have taken a shot of where to look for a possible vacuum leak . As shown the first picture is of the hose coming from the vacuum pump,check out for cracks ,the second is the tee off just up from the vacuum pump ,yours may be covered with insulation for heat .Remove the whole tube and replace without the insulation ,mine was cracked under the insulation . The problem is vacuum loss and if dont find any issues with the two areas i have just mentioned then you need to systematically go through all vacuum lines until you find the leak . Be aware that these engines do not produce manifold vacuum ,hence the additional vacuum pump

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    Default Power Loss Eunos 800M

    Quote Originally Posted by chrismurphy View Post
    see this link for photos and manuals for your milly



    Look at the photos section ,I have taken a shot of where to look for a possible vacuum leak . As shown the first picture is of the hose coming from the vacuum pump,check out for cracks ,the second is the tee off just up from the vacuum pump ,yours may be covered with insulation for heat .Remove the whole tube and replace without the insulation ,mine was cracked under the insulation . The problem is vacuum loss and if dont find any issues with the two areas i have just mentioned then you need to systematically go through all vacuum lines until you find the leak . Be aware that these engines do not produce manifold vacuum ,hence the additional vacuum pump
    Hi Chris
    Many thanks for your reply. I am having trouble opening your photos at mediafire. I have a copy of the vacuum lines schematic for the Eunos 8oom. Would this be the same? Also, what do I have to remove in the way of covers, etc., to search for the vacuum lines?
    Warm regards
    Lawrie

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    Smile Power Loss Eunos 800M Engine

    Quote Originally Posted by LawrieM View Post
    Hi Chris
    Many thanks for your reply. I am having trouble opening your photos at mediafire. I have a copy of the vacuum lines schematic for the Eunos 8oom. Would this be the same? Also, what do I have to remove in the way of covers, etc., to search for the vacuum lines?
    Warm regards
    Lawrie

    Hi Chris
    I have been able to finally download the two photos from MediaFire. Thank you again.
    I will now get to work!
    Warm regards
    Lawrie

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    Quote Originally Posted by chrismurphy View Post
    The problem you are ecperiencing is due to a vaccum issue .reply and i can walk you through a fix
    Hi Chris

    I have exactly the same problem as you answered here.

    TCS light comes on, and engine pulsates under acceleration with no power.
    Switching off engine, and restarting, corrects TCS light, and engine runs normally.

    Could you walk me through the solution to my problem?

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