Heat under the hood etc.
Discussion
Following on from my "Water injection etc." post the other day I have been giving more thought to reducing the air temperature entering the engine. One area that seems to get a bit of of discussion is reducing the temperature of the plenum and inlet bit n pieces because in theory they heat up the air entering the engine (and I realise insulation gaskets are available to help with this).
At 3,000rpm I believe there is around 100 litres of air entering the engine every second, that's quite a lot of air!
I am struggling in a very big way to see how a hot plenum/inlet tract can heat up that amount of air in 1 second hence is this heat reduction thing legitimate or just a lot of hot air? (Sorry couldn't resist it!).
It seems to me ensuring that the air entering the filter is as cool as possible to start with and therefore concentrating on moving the filter or looking at ducting etc. (or water injection!) is the way to go.
Any feedback welcomed!
Tim (1990 400SE)
At 3,000rpm I believe there is around 100 litres of air entering the engine every second, that's quite a lot of air!
I am struggling in a very big way to see how a hot plenum/inlet tract can heat up that amount of air in 1 second hence is this heat reduction thing legitimate or just a lot of hot air? (Sorry couldn't resist it!).
It seems to me ensuring that the air entering the filter is as cool as possible to start with and therefore concentrating on moving the filter or looking at ducting etc. (or water injection!) is the way to go.
Any feedback welcomed!
Tim (1990 400SE)
Edited by TimboNZ on Thursday 17th November 20:51
Edited by TimboNZ on Thursday 17th November 20:58
Cold air is always good, but you have to temper that with the possibility of pulling in rain and floodwater (or snow if you're in northern climes!). This is the normal compromise with production designs and is probably why the standard filter is up high behind the rad. Pressure drop/loss is the other reason the filter is where it is but long straight pipes have low pressure loss so it won't be the primary driver. Anyway I'd wager that TVR power/torque figues were taken on an engine dyno so the car air intake system probably didn't feature in the equation!
The airflow at max power/torque is huge so the plenum temp is unlikely to make a difference but you will very rarely be at these conditions (ie full throttle). At idle and part throttle the air will pick up plenum heat; this will manifest itself in sluggish pullaway when the engine bay is hot. This is probably why insulated/carbonfibre plenums subjectively make a difference.
The airflow at max power/torque is huge so the plenum temp is unlikely to make a difference but you will very rarely be at these conditions (ie full throttle). At idle and part throttle the air will pick up plenum heat; this will manifest itself in sluggish pullaway when the engine bay is hot. This is probably why insulated/carbonfibre plenums subjectively make a difference.
Thanks Hatter
I think the chances of encountering floods or snow in NZ are reasonably rare however even though I don't drive my beasty in the rain that does need taking into account if you're going to do the job properly. A side facing entry coming off a 'collection chamber' maybe?
I don't see pressure drop as an issue really but perhaps could go for a larger diameter hose just in case.
Even at 3,000rpm I just cannot comprehend 100 litres of air being heated up in 1 second. There's still 30 litres a second passing through the system at idle and even that getting heated I struggle with!
Do carbon/insulated plenums actually make a difference though? They sure look pretty and in many cases are part of a plenum/trumpet tune but I haven't found anything to suggest they do in my searching so far!
Cheers!
I think the chances of encountering floods or snow in NZ are reasonably rare however even though I don't drive my beasty in the rain that does need taking into account if you're going to do the job properly. A side facing entry coming off a 'collection chamber' maybe?
I don't see pressure drop as an issue really but perhaps could go for a larger diameter hose just in case.
Even at 3,000rpm I just cannot comprehend 100 litres of air being heated up in 1 second. There's still 30 litres a second passing through the system at idle and even that getting heated I struggle with!
Do carbon/insulated plenums actually make a difference though? They sure look pretty and in many cases are part of a plenum/trumpet tune but I haven't found anything to suggest they do in my searching so far!
Cheers!
Hi tim - I'm not very far away from you, except for the ferry ride (wot, it's broke down AGAIN ?)
Quite few std cars can be seen with hoses to the front for cold air. On my 280 I added a 'baffle' type plate to make sure I get air that hasn't been through the rad. ('K' injection box doesn't have a neat circular intake, so a hose is hard to do) Not sure if it makes that much difference, but cold air is supposed to give a few more bhp.
Might help if you get pinking on the unleaded though....
Quite few std cars can be seen with hoses to the front for cold air. On my 280 I added a 'baffle' type plate to make sure I get air that hasn't been through the rad. ('K' injection box doesn't have a neat circular intake, so a hose is hard to do) Not sure if it makes that much difference, but cold air is supposed to give a few more bhp.
Might help if you get pinking on the unleaded though....
You don't get anything like 30 litres/sec at idle; that would be the flow rate if the throttle was wide open at idle speed. Clearly the throttle is almost shut and there's a big vacuum in the intake manifold, and airflow rate is tiny. I've seen a 2.0 litre engine idling on the air supplied through a 4mm diameter hole... funnily enough it wouldn't rev!
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