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Bonnet scoop mesh mod
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Old 27 Aug 2004, 09:09 PM   #1 (permalink)
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Bonnet scoop mesh mod

I recently asked a question on here about where to find mesh suitable for fitting behind the bonnet scoop of my WRX Sti. Thanks to those that replied, they gave me some useful links. But in the end I found some locally, aluminium stuff which turned out to be perfect as it was really easy to mould into shape
If anyone wants to know how to do this mod let me know, in the mean time I've attached photos of the job so please let me know if you think it looks cool or crap.

Oh and if anyone spots the silver clips on the lower rad grill which are clearly visible and look a bit naff - already spotted it, gonna paint em black to hide em.
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File Type: jpg intercooler_grill.jpg (18.0 KB, 19 views)
File Type: jpg both_grills.jpg (25.1 KB, 21 views)
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Old 27 Aug 2004, 09:29 PM   #2 (permalink)
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Looks very good, nice one
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Old 27 Aug 2004, 10:52 PM   #3 (permalink)
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Like that :P - Good job, what did the mesh set you back after?

Thanks in advance :P
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Old 28 Aug 2004, 11:46 AM   #4 (permalink)
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Glad you think it looks ok guys, didnt want it to look cheesy.

The Alu stuff was from DRB motors Warrington (hope I can say that??) 25 quid gets you enough to do all the grills at the front, including the 2 small black grills under the reg plate. I went for the standard silver colour diamond mesh but they also do other shape holes and colours, could also be sprayed to match the car

Subaru use nasty black painted steel mesh which is a shame for such a quality motor.

Cheers
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Old 28 Aug 2004, 09:30 PM   #5 (permalink)
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centaur25

Looks like you made a good job centaur .

Do you have a link to where you bought the mesh?
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Old 30 Aug 2004, 09:32 AM   #6 (permalink)
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Sorry Cat17, no link but I have the address and phone no: I'm sure they will send you some, however the mesh is nothing special - any good car modding/spares shop should stock it.

DRB Car Spares & Accessories
25 Orford Green
Warrington
CHESHIRE
01925 415294
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Old 30 Aug 2004, 10:12 AM   #7 (permalink)
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Thats a good price for an eye catching mod - Should stop the big nasties denting the fins on the intercooler :P - I'll be digging some big nasties out of mine in a few weeks
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Old 30 Aug 2004, 01:20 PM   #8 (permalink)
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I think it looks very good indeed but....
and I know I'm going to sound like a complete anorak here but....
Being an engineer involved in fluid flows etc I can imagine, not calculated yet, but the mesh will reduce airflow to the intercooler by around 40 to 45%.
Not too bad in cooler condition but in hot weather will potentially cause boost temperature problems. :cry:
Prehaps that is why Subaru do not fit mesh as standard.

Sorry to be a little negative about a good looking mod

Cool.
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Old 31 Aug 2004, 09:29 AM   #9 (permalink)
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Interesting point Coolangatta, one I did consider but did not make any calculations for being quite lazy .
TBH though i'm waiting to see if there is any impact on engine temps or performance - none so far.
However as I too work in engineering I would be interested in seeing the calculation you applied to reach a flow restriction figure of 40-45% or was it a best guess based on experience? I'm not being a flamer here, I'm genuinely interested as the car is still under warranty and I wouldn't want to risk problems in the event of a claim.

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Mike
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Old 31 Aug 2004, 09:46 AM   #10 (permalink)
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maybe because it looks like 50 percent of the hole is now blocked, just my opinion ops: . i'm far from an expert :shock:
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Old 01 Sep 2004, 12:27 AM   #11 (permalink)
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Mike
Yes it was just a best guess.

As you are well aware this is not a forced air system.
Therefore intercooler inlet and exhaust areas are designed, with forward motion induced airflow in mind, to provide the necessary heat rejection rates.
Full throttle and full boost can equate to inlet temperatures between 121 and 176 deg. C depending on turbo size etc. This temperature needs to be reduced to provide an air density increase and reduce the likelihood of detonation.
So the inlet area is critical.
Calculations will have been made by Subaru engineers to provide an inlet area conducive to giving the required heat exchange with a margin applied to take into account a maximum, notional, outside air temperature.
I think that the reduction in total inlet area should not be the only consideration,
recirculating airflow effects need to be taken into account.
The mesh may produce recirculating airflows immediately behind it and therefore compound the effective airflow reduction from the reduced inlet area.

As previously stated, in a moderate climate, such as the UK’s, under ‘normal’ driving conditions, I would not expect temperatures to be excessive.
But in hot weather, combined with ‘spirited’ ‘on boost’ driving, temps may become elevated.
I have read of owners in hotter countries monitoring boost temperatures and moderating their driving style depending on those temperatures, i.e. keeping off boost
It is also worthy of note that some drivers switch to front mounted intercoolers to increase effective airflow and exchange rates.

Do you have IC water spray :?: This would obviously be of benefit during hot weather.

I think the mod looks very good and you obviously considered any potential problems before going ahead, so well done. My observation was based in a concern that you had already considered.
Nice car too BTW. 8)

Cool.
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Old 03 Sep 2004, 11:10 PM   #12 (permalink)
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Thanks for the info and advice coolangatta, excellent post.
I have to admit I certainly didn't consider recirculating airflow effects! Maybe I should have?
The mesh is basically aluminium sheet with diamond holes punched into it. These holes are actually quite free flowing although they dont really look it in the photos, due to the 'shutter effect' way the sheet was reformed.
For now i reckon I'll keep monitoring temps (although I cant monitor intercooler temp) and also monitor general performance and see how it goes, shame if I have to remove it though.

Ps... Just fitted a Ninja back box... WOW what a noise my scoob makes now :shock: . Not sure if I need to reset the ECU though to re-map for the new zost? Any thoughts??

Cheers, Mike
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Old 03 Sep 2004, 11:16 PM   #13 (permalink)
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Im pretty sure Subie gal uses this sort of thing (north america) - and shes said they donet affect her performance in any way... i could have just made that up but cant remember :P Its on this forum somewhere i just cant find it :P

let us know how it goes? I could see a problem if i were in the hottest country god put on this planet (coolangatta in n.japan :P ) nut may not be a prob pver here???
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Old 16 Sep 2004, 04:35 PM   #14 (permalink)
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Quote:
Originally Posted by 1999Turbo
Im pretty sure Subie gal uses this sort of thing (north america) - and shes said they donet affect her performance in any way... i could have just made that up but cant remember :P Its on this forum somewhere i just cant find it :P

let us know how it goes? I could see a problem if i were in the hottest country god put on this planet (coolangatta in n.japan :P ) nut may not be a prob pver here???

tis true
i run grillcraft grills on the rally car
no issues with heat/overheating and they work well!

grills:





grills in action (notice bottom grill! kept out the mud from my radiator... )



Jamie
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