The difference between sucking & blowing! - Page 10 - Renault Forums :: Independent Renault forum

View Poll Results: In your opinion/experience does air filter choice affect the turbo's lifespan?
Absolutely, more power through greater efficiency - can only be a good thing. 11 64.71%
Keep it standard, that way its the manufacturer's responsibility if it goes bang. 3 17.65%
Don't know/care one way or another. 3 17.65%
Voters: 17. You may not vote on this poll

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post #46 of 71 (permalink) Old 10th July 2008
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I can understand why most people think that more oxygen is the deal solution for running a petrol engine. The fact is that there is a trade off between too much and too little air.
Petrol concentrations below 1.4%, in air the mixture is too lean to ignite, and for those above 7.6% too rich; at all concentrations between these two limits, a mixture of petrol vapour and air will ignite.
But with more air (think oxygen) the combustion is likely to be complete with some oxygen not being used - this is the most efficient i.e. better economy. On the other hand reducing the air allows more power per stroke to be developed. So in reality allowing more air into the engine may reduce its power output but improve its economy. You just can't have the benefit of both although lean-burn engines such as the IDE and Gdi have attempted to address this problem but as we all know it hasn't been without its difficulties. No doubt engine designers for the public motor market have to strive to get the balance between the two - so it is actual possible that by allowing more oxygen into the fuel mix power output may be reduced. It all about getting the mixture correct for whatever you want an engine to do at a particular time throughout its power range. From my experience I have found petrol engines perform that wee bit better when the fuel mix is slightly rich but tend to be that bit thirstier and I have yet to see a high performance engine easy on fuel.

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post #47 of 71 (permalink) Old 10th July 2008
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Originally Posted by Pat.w View Post
if you read back a bit, you will see that I brought this up in reference to a supposed requirement for dry air.
Sure did Pat

Originally Posted by Pat.w View Post
Adding water into the fuel air mix is certainly a performance boost. It increases the compression ratio, and improves the burn rate.

That'll be the bit


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post #48 of 71 (permalink) Old 10th July 2008
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Originally Posted by Gonescenile View Post
Sure did Pat

That'll be the bit

post #49 of 71 (permalink) Old 10th July 2008
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Perhaps this thread is getting a little off track again

I may be wrong (it happens more regularly than I would like ) but I don't think the question was what is the perfect mixture, more is a free flowing airflow preferential on a turbo engine and how would that effect the performance of the turbo .

The way I understand a turbo is that the exhaust fumes are the main drive, but it's actually a balance of pressures/flows that allow it to spool up rather than a volume of exhaust gas alone. So, if the air in the intake remains static but more exhaust gas is being pushed through, the turbo 's rpm increase will be restricted. Iím positive that it wonít matter which end the restriction is, if the air in the intake is allowed to flow as freely as possible there must be less restriction on the compressor making it easier for the exhaust gasses to spool up the turbo .

I would assume that any restriction as mentioned above could add a load to the bearings that the turbo shaft runs on and that this load would not be ideal. As to this decreasing the life of the turbo , I have no idea, but surly it canít help.
post #50 of 71 (permalink) Old 10th July 2008
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My understanding of compressers is that if you restrict the air flow (ie put your hand over the intake) then it will still spin but just not compress. A turbo will be he same so in terms of a turbo doing its job the more free flowing the air intake the better the turbo will perform though i don't think thatit would make any ifference to the life of the turbo there are far to many things that effect its life for the filter type to make much of a difference.
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