Silencer Issues on 1.4 Engine in R8
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  1. #1
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    Default Silencer Issues on 1.4 Engine in R8

    I have had a Virage engine in my R8 for years and I've never been happy with its performance above about 3500 rpm. Nice idle, plenty of torque and smooth from 1000, but harsh, noisy and unpleasant at revs, so that it's unpleasant at 90kim/h, even though it will wind up to 120 at which point it's clearly unhappy.

    It's a standard motor with low mileage, but because I wanted the installation to look like a standard 1100 R8 engine compartment, I used a standard R10 exhaust manifold and muffler setup, knowing it would be somewhat restrictive, but wanting it to be quiet. Could it be this that is the problem? I have some friends who say that the Virage engine, with its surprising camshaft timing of 22/62/62/22 would be strangled by a very short, restrictive and tiny muffler. Maybe it's true. I'm so fed up with it I've pulled out the motor, but other than cam followers looking a little unevenly worn, it all seems fine.

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    Could it really be the exhaust system killing the top end? And do I have to have an unsightly and noisy exhaust? Any and all suggestions gratefully received!

    Cheers, Clive

  2. #2
    1000+ Posts Frans's Avatar
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    Clive,
    I think so. You have 20% more cc s and a cam that is so much hotter than what the 1100 system is designed for. Your cam that you mentioned gives you a 264 degrees advertised duration, the outlet and inlet system was designed for a 224 degrees advertised duration. Put it all together and you will see firstly 20% more cc, that is bad for your inlet and outlet system. Then you have 15% more duration that wants to take in a whole lot more and after combustion it has to get rid of the whole lot more that it tried to take in.
    These things makes such a huge difference that one think is negligible but in the mean time.......no power. For a sample, cam timing that is out by one tooth is about a 5% error. Have you driven a car with cam timing out by one tooth? It is useless.
    Then another thing that comes to mind for explanation, the working of an engine is based upon taking air in, burn it and get rid of it. The more of that the more hp.
    I love exhaust systems and I've mentioned it so many times on AF that if you are going to spend money or muscle power on it, you might as well do it the right way and get a calculated one made.
    Regards
    Frans.
    Old enough to know better
    Young enough to do it anyway.

  3. #3
    Too many posts! JohnW's Avatar
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    Quote Originally Posted by Frans View Post
    Clive,
    I think so. You have 20% more cc s and a cam that is so much hotter than what the 1100 system is designed for. Your cam that you mentioned gives you a 264 degrees advertised duration, the outlet and inlet system was designed for a 224 degrees advertised duration. Put it all together and you will see firstly 20% more cc, that is bad for your inlet and outlet system. Then you have 15% more duration that wants to take in a whole lot more and after combustion it has to get rid of the whole lot more that it tried to take in.
    These things makes such a huge difference that one think is negligible but in the mean time.......no power. For a sample, cam timing that is out by one tooth is about a 5% error. Have you driven a car with cam timing out by one tooth? It is useless.
    Then another thing that comes to mind for explanation, the working of an engine is based upon taking air in, burn it and get rid of it. The more of that the more hp.
    I love exhaust systems and I've mentioned it so many times on AF that if you are going to spend money or muscle power on it, you might as well do it the right way and get a calculated one made.
    Regards
    Frans.
    I don't know enough to discuss at Frans' level, and don't disagree. The exhaust system on your car is much what the original 845cc Dauphine Gordini had, and certainly the 956cc early R8 so, ignoring valves and in-head ports, a 1.4 is approaching twice the engine capacity of the original exhaust design.

    I would make one comment though, and we've had two 1.4 R12s over the years. I didn't much like the engine of either car, although totally reliable - they didn't really spin and never felt "willing" at all. Power and torque low down perhaps, but not much more.

    Be interesting to see what other people say.

    There are others out here who know much more than I do.
    JohnW

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  4. #4
    1000+ Posts renault8&10's Avatar
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    I've a spare exhaust similar to my white R10 setup you could borrow and try.
    My old exhaust is actually on Denis' car at present I think, but I have another complete setup at home.

    It would work with a side draft manifold or an R12 downdraft, but not the original R8 inlet I think.
    KB
    KB


  5. #5
    1000+ Posts J-man's Avatar
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    Default Silencer Issues on 1.4 Engine in R8

    Hi Clive, here is a picture of the set up I've just taken off in lieu of extractors and sports system. It used standard Virage inlet and exhaust manifolds. There were no issues with lacking power and the exhaust wasn't noisy. These cars are pretty noisy from the engine at speed anyway in my opinion but mine used to be particularly noisy from a collapsed gearbox mount transferring noise through the car. With new engine & gearbox mounts, it's significantly quieter at high speed.

    Attachment 56830
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    Attached Thumbnails Attached Thumbnails Silencer Issues on 1.4 Engine in R8-imageuploadedbytapatalk1401614474.673417.jpg  
    Last edited by J-man; 2nd June 2014 at 10:04 AM.
    cheers,

    John

  6. #6
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    Hi all, will respond to your posts tomorrow, when I have some time. And thanks a lot!

  7. #7
    Fellow Frogger! rubyalpine's Avatar
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    It is a well known fact that (all things being equal) a long stroke motor will not rev as freely as a short stroke motor, and the longer stroke motor will normally have more torque at lower r.p.m. Therefore it is quite normal for the R12 motor to less happy to rev. like the 1108cc motor does. Despite this, improving the breathing out, will surely improve the performance, and maybe the economy as well. Remember it's no use trying to get more in if you can't get it out! I agree with Frans that the number one engine mod. to consider, is an efficient exhaust system.

    Henry

  8. #8
    1000+ Posts alan moore's Avatar
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    Quote Originally Posted by Frans View Post
    Clive,

    These things makes such a huge difference that one think is negligible but in the mean time.......no power. For a sample, cam timing that is out by one tooth is about a 5% error. Have you driven a car with cam timing out by one tooth? It is useless.

    .
    Is it possible that even though the inlet and exhaust are not the best available, that the cam timing is advanced by a tooth making it not want to rev but will give very good low down torque. It is easy to check by bringing the engine up to top dead centre and checking that a cylinder on overlap has the same amount of lift on both inlet and exhaust valves, approx 1.5mm in your case. If you are out by a tooth it will be very obvious.

    I remember being raced around in a 1.4 back in the early '80s,and being quite amazed that it would rev and pull quite hard to about 6500rpm and that it didn't seem to run out of breath or get harsh at all.
    '56 Renault 4CV (16TS Power)
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