Bonnet scoop on RRC

That was an interesting link.

One question I do have after reading it is whether fitting underbody protection such as a steering guard and bash plates for the transfer, transmission and fuel tank would interfere with the venturi effect in which careful design can cause a low pressure area to occur under the vehicle, increasing down force.
While down force isn't important on a 4WD, and the designers may not give it much consideration, it is important for cooling to have a low pressure area rear of the radiator so air is drawn through it from the high pressure area ahead of the radiator, as air naturally flows from high to a low pressure area, trying to equalise the pressure.
So, would underbody protection plates interfere with the air flow? Would cooling efficiency be reduced, or even increased?
I have no idea. Any thoughts?

With the whole car, you'd never know without a wind tunnel or an enormous amount of measuring, point-by-point, under the car. However, in the engine bay you could just do what I was describing before with a long hose, one end in the car, one end where you want to measure, and do comparisons that way.

I've put a flat bit of metal from under the bullbar bumper to a steering guard, (the factory type, which is a big bit of pipe: NRC7009 - just so you can picture it), and sealed up the bonnet. I know I'm getting low pressure because of it, but haven't had the chance to measure it yet.

Interestingly, that factory fitted a plastic thing under the front of the engine bay on some '90s models, MWC6937, which is referred to as a "cooling tray", (or something like that), in some factory books. I think it was used in conjunction with that plastic front spoiler under the bumper, but I still haven't worked out what it was supposed to do. I'm going to make something similar and see what happens - I've got to do the measurements as above first, though.

Yes, it's certainly just guesswork without a wind tunnel.
I had assumed steering guards should have lots of holes to let plenty of air blow through, but now I'm wondering if that is right.
I doubt if the designers of underbody protection for 4WDs think much about aerodynamics.

The wording in the box under the blue Subaru may be of interest .

Seems the important part is not getting air in .

Tells a bit about pressure in the engine bay .






AutoSpeed - Undertrays, Spoilers & Bonnet Vents, Part 1

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Originally Posted by Davo

Hey, get out of here with yer learnin'! [biggrin] Thanks for the link. That's the kind of thing people need to read to get a start on this. There is so much really good information out there these days that this biggest problem is wading through it all.

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G`day ,

yea , learnings good i learn lots new just wish i had the capacity to retain in detail .


Your Pub Forum comment made me smile but then i thought there are plenty of people that read only on the forum and a lot of those have information to contribute but because of how things do happen they don`t .

It has always amused me when someone says i`m going or not taking about the subject any more . If your not involved how can you contribute or change things .

Quote:

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Originally Posted by PLR

The wording in the box under the blue Subaru may be of interest .

Seems the important part is not getting air in .

Tells a bit about pressure in the engine bay .






AutoSpeed - Undertrays, Spoilers & Bonnet Vents, Part 1

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Thanks for that link, too. Yes, I did appear to have some slight difficulties in getting this exact point across recently. [bigwhistle] Autospeed is excellent and is where I really started to actually learn about this stuff, instead of just guessing. Then I found reports and technical sites and have kept trying to learn.

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Originally Posted by PLR

G`day ,

yea , learnings good i learn lots new just wish i had the capacity to retain in detail .


Your Pub Forum comment made me smile but then i thought there are plenty of people that read only on the forum and a lot of those have information to contribute but because of how things do happen they don`t .

It has always amused me when someone says i`m going or not taking about the subject any more . If your not involved how can you contribute or change things .

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I think that's become a big problem here, but during a discussion last year others didn't agree because, apparently, the number of members are up. But I joined this forum because the technical stuff was so good, and now it seems that some of the ridiculous infighting in areas like General Chat put a lot of good people off. I've found some of the moderation when this happens to be a bit lacklustre, to say the least.

Quote:

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Originally Posted by Davo

I think that's become a big problem here, but during a discussion last year others didn't agree because, apparently, the number of members are up. But I joined this forum because the technical stuff was so good, and now it seems that some of the ridiculous infighting in areas like General Chat put a lot of good people off. I've found some of the moderation when this happens to be a bit lacklustre, to say the least.

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It`s good i guess that i`m of a similar mind .

I`ve asked questions and made suggestions about nonexistent concerns . Discussion there was none there needs to be a problem . It`s related the forum goes against the trend with new members but if you look at the members list there are many dormant non financial . The number of hits on a subject or area is the gauge .

The slowing of new posts and new posters seems real but is my preconception .

To my wonderment during one of my presuming i had some sort of entitlement to think about what i thought could improve the forum ( which i was shown i don`t ) i was asked if i was alright .

None of this is of course helpful and will receive the naysayers label but at least nowdays the dogs are only puppys .

I apologise for putting this in what i once considered sacred ground ( too much ? ) but it has also been related that nowdays anything can go anywhere and does it matter .

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Originally Posted by Davo

. I've found some of the moderation when this happens to be a bit lacklustre, to say the least.

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I'm sorry you feel this way Davo,,
If the Moderation is not up to scratch Please REPORT the offending remarks,,
failing that, please email Incisor.

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Originally Posted by Pedro_The_Swift

I'm sorry you feel this way Davo,,
If the Moderation is not up to scratch Please REPORT the offending remarks,,
failing that, please email Incisor.

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It's been mentioned in a thread or two, particularly one thread from last year, but nobody seems to get it. It's not a matter of reporting offending remarks, it's when a moderator doesn't even understand a problem in the first place and blunders their way to an answer which suits them but doesn't actually address anything. I doubt that's something that's going to improve unless we have some moderators to moderate the moderators. [bighmmm]