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Thread: Bonnet scoop

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    Bonnet scoop

    Because it's positioned directly above the turbo and exhaust manifold, a lot of heat gets conducted into the inlet manifold.

    After driving the car for a while, the inlet manifold is pretty hot to the touch, which would would surely negate all the cooling that the intercooler has just done?

    I'm toying with different ideas for trying to prevent this including, heat wrap, carbon heat shield, and naca bonnet vents and louvres.

    Would it be effective to set up some sort of venting system whereby air is taken in through the front of the bonnet, ducted past the inlet manifold, and then use louvres at the rear of the bonnet to exhaust the heat?

    I'm open to suggestions and alternatives.

    Here's a very rough, and incredibly not to scale diagram of what I'm proposing.

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    Last edited by petrolh34d; Friday 17th June 2016 at 01:52.
    Silver - 1999 Volvo V70 - 2.5 TDi - Miles: 200,000
    Scrapped: Silver - 1998 Volvo V70 - 2.5 TDi - Miles: 300,000+

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    With over 230bhp (soon to be more ) I've not found the need for it yet. I wouldn't worry about it or waste money on it myself.
    854 T5 - The new project.

    850 tdi - sorely missed.

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    a 19t just isn't laggy enough
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    i removed the rubber seal at the rear edge of the bonnet

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    Quote Originally Posted by JT View Post
    Be good if they did one for the tdi..
    854 T5 - The new project.

    850 tdi - sorely missed.

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    Quote Originally Posted by martin_r_smith View Post
    Be good if they did one for the tdi..
    just an idea, I have no idea if they make 1 for the tdi...

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    unfortunately not, there is nothing really that's made specifically for this engine.

    It would be of no performance benefit on a tdi either, the engine doesn't know if it is getting hot, warm or cold air post turbo as it only measures at the maf. And unlike a petrol there is no lambda sensor to tell the ecu what the mixture is doing so it cannot compensate for a greater or lesser quantity/ density of air and adjust fuel accordingly. The fueling is basically metered by inlet temp at the maf, manifold pressure and throttle position (plus a few others like fuel temp etc), so even if you got the post intercooler temps to say 10 degrees but the temp at the maf is 24, it will still fuel for 24 not 10.

    Hope that makes sense.
    Last edited by martin_r_smith; Friday 17th June 2016 at 10:50.
    854 T5 - The new project.

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    Double post
    854 T5 - The new project.

    850 tdi - sorely missed.

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    Thanks guys, some helpful info there.

    I didn't know that was the way that the fuelling was ratioed Martin. It seems odd to me to go to the bother of intercooling the charge, and then porting it into the engine via a hot intake manifold.

    So the most important thing to consider regarding power is the air/fuel ratio, which is determined purely by the MAF?

    If the fuel ratio is unaffected after the MAF, how does the intercooler affect the equation?

    Thanks
    Silver - 1999 Volvo V70 - 2.5 TDi - Miles: 200,000
    Scrapped: Silver - 1998 Volvo V70 - 2.5 TDi - Miles: 300,000+

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    Quote Originally Posted by petrolh34d View Post
    Because it's positioned directly above the turbo and exhaust manifold, a lot of heat gets conducted into the inlet manifold.

    After driving the car for a while, the inlet manifold is pretty hot to the touch, which would would surely negate all the cooling that the intercooler has just done?

    I'm toying with different ideas for trying to prevent this including, heat wrap, carbon heat shield, and naca bonnet vents and louvres.

    Would it be effective to set up some sort of venting system whereby air is taken in through the front of the bonnet, ducted past the inlet manifold, and then use louvres at the rear of the bonnet to exhaust the heat?

    I'm open to suggestions and alternatives.

    Here's a very rough, and incredibly not to scale diagram of what I'm proposing.

    Name:  vent.png
Views: 0
Size:  301.5 KB
    But the inlet is at the front of the engine...
    19t, greens, 3" inlet, 3" downpipe with race cat, V70R catback, autotech map...

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    Quote Originally Posted by M-R-P View Post
    But the inlet is at the front of the engine...
    Not on the derv, Martin

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    Quote Originally Posted by Doingitsideways View Post
    Not on the derv, Martin
    oh.

    19t, greens, 3" inlet, 3" downpipe with race cat, V70R catback, autotech map...

    310.2bhp / 333ft/lb

    2016 Swedish Day UK "Best Modified Swede"
    SOLD

    Got an old discovery now.

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    The intercooler does not affect the fuelling at all, it is simply there to bring the air temp down to something similar to the air going in at the maf. These old dervs don't have clever management and many assumptions are made rather than using sensors for feed back.
    854 T5 - The new project.

    850 tdi - sorely missed.

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    petrolh34d (Sunday 19th June 2016)

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    Quote Originally Posted by martin_r_smith View Post
    The intercooler does not affect the fuelling at all, it is simply there to bring the air temp down to something similar to the air going in at the maf. These old dervs don't have clever management and many assumptions are made rather than using sensors for feed back.
    Cool. So it's basically guess work after the MAF, as the intake temperature can change without the MAF actually knowing.

    I think I'm gonna have a stab at some sort of ducting system, purely our of curiosity and the desire to experiment.

    Nice Claymore! I think it may have been seeing your design some time ago which has subconsciously inspired me.

    Did you have an Integrale vent on your bonnet at one stage?
    Silver - 1999 Volvo V70 - 2.5 TDi - Miles: 200,000
    Scrapped: Silver - 1998 Volvo V70 - 2.5 TDi - Miles: 300,000+


 

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