Effective Bonnet Venting For Turbos

[DJRIFT]

after a few hours running a highmount turbo on the drift car we found it had generated massive engine bay temps even thoe we were running a vented bonnet.

this is the bonnet

i know that the R34-R35 GTR run the naca duct to force air down onto the turbos for cooling but would it be more efficent to vent the heat from a high mount turbo up and out of the bonnet?

if anyone has any pictures of a good solution id be very gratefull.

i personaly have never seen anything like what im thinking of.

on another note i was taking to an EVO guroo one day and he recconed that having the turbo behind the radiator was ideal on an evo because the turbo got consistant airflow over it helping to keep temps in check. does anyone run any sort of turbo air cooling?

[N1GTR]

Is the turbo ceramic coated?

[toddlls]

The only thing I can think of is placing the duct further back or on turbo side, seems to me that all frontal air after coming thru opening/radiator is travelling straight up & out rather than passing all way round motor then down the tunnel to underside of the car, otherwise have you tried the 5 or so washers on bonnet hinges to give airflow out?

[sav man]

heatwrap the manifold, and put a bag on the turbo. It's the only way to stop the kind of heat that's being generated under there.

[JayM35]

heatwrap the manifold, and put a bag on the turbo. It's the only way to stop the kind of heat that's being generated under there.

Yep, however don't heat wrap cheap chinese manifolds, they don't like it.

Those NACA ducts are very effective, we found more gain with them over the full cheese grater vents.

[DJRIFT]

Is the turbo ceramic coated?

nope. what is good ceramic coating worth these days and where the best place to get it done?

The only thing I can think of is placing the duct further back or on turbo side, seems to me that all frontal air after coming thru opening/radiator is travelling straight up & out rather than passing all way round motor then down the tunnel to underside of the car, otherwise have you tried the 5 or so washers on bonnet hinges to give airflow out?

id never thought about it that way. so the air coming in through the rad escapes throught the front of the bonnet meaning no air flows throght the rest of the engine bay?

and we also had the bonnet spaced up to clear the cooler piping so that didnt help.

Yep, however don't heat wrap cheap chinese manifolds, they don't like it.

Those NACA ducts are very effective, we found more gain with them over the full cheese grater vents.

do you have any pictures of how you used the? did you use them to duct cold air into a particular spot. or for removing hot air? what things in particular did you cool with them?

[emtea]

Here is an article about this stuff on Autospeed: http://autospeed.com.au/cms/title_Undertra...9/article.html 

That is part 1 of 3, but basically the air coming into the engine bay has to have an escape route, otherwise pressure just builds inside the engine bay...

[JayM35]

do you have any pictures of how you used the? did you use them to duct cold air into a particular spot. or for removing hot air? what things in particular did you cool with them?

No sorry, was on my old series 1 rx7, was just used to cool air box(ontop of carb).

Was just a duct and about 4 inches of flexitube aimed at front of airbox.

Havent tried it with my Series 6, I did try space the bonnet but didn't make much difference according to the Link meters, but its a NA, turbo applications may differ.

Start with those radiator splitters, that stop air escaping over your radiator, and play with under car splitters too, diverting air in and around bottom of your engine.

I'll be playing with different things this racing season so will post up results, is only a s6 rx7 but should help skylines out with future builds.

[R31Nismoid]

Certainly sounds like better heat shielding is needed - what is currently being used?

[DJRIFT]

Certainly sounds like better heat shielding is needed - what is currently being used?

nothing really. it was more just like radiant heat soak from no ventilation at all.

[R31Nismoid]

Heat shield it then mate

Will make ALL the difference.

With my manifold's shield off on my GTS-R manifold everything in my engine bay was crazy hot. Even the strut tower was ridiculously hot and mine was all low mounted.

Puting the heat shield back on and everything like strut towers etc were back to much cooler temps.

Heatshielding stops that radiant heat quite effectively. I'd go that route before more venting.

Just bent up some ally to cover the turbine housing, and another to plate over the manifold if possible to deflect/stop from radiating out and head down.

[DJRIFT]

year right.

ive seen good results using the acl stuff so ill grab some of that. its cheap to.

[carcouture]

after a few hours running a highmount turbo on the drift car we found it had generated massive engine bay temps even thoe we were running a vented bonnet.

this is the bonnet

i know that the R34-R35 GTR run the naca duct to force air down onto the turbos for cooling but would it be more efficent to vent the heat from a high mount turbo up and out of the bonnet?

if anyone has any pictures of a good solution id be very gratefull.

i personaly have never seen anything like what im thinking of.

on another note i was taking to an EVO guroo one day and he recconed that having the turbo behind the radiator was ideal on an evo because the turbo got consistant airflow over it helping to keep temps in check. does anyone run any sort of turbo air cooling?

Here a picture of my vents - I place them above the turbo to get the excessive heat out - its a T88-34D with a HKS heat shield, titanium wrapped downpipe - that we a fair bit of the heat is coming from. In excess I will stick heat reflective gold foil on the bottom side of the vented turbo area.

Uploaded with ImageShack.us

[Ghostrider]

For what it's worth, I have done this to a standard metal DR30 Iron Mask bonnet for similar results to what you want.

Simple physics is that air flows over an vented object creating a low pressure area under the vent and therefore sucks the air out of the vents as it passes over the top.

When looking at the picture, the 6 front vents sit very nearly at the front of the engine and rear of the radiator. This is designed to increase the air flow through the radiator & intercooler and disperse the heated air out the top. The vents/louvers circled sit just above and slightly to the rear of my high mount and is designed to take the hot air away from the turbo.

I'm also using an turbo sock on the exhaust housing and a ceramic coated manifold.

Where are you in the island state?

HPC in Melbourne are or have been experiencing problems with the coating flaking inside the manifolds and last I heard they are no longer coating inside prior to the turbo, thus trying to eliminate engine failure due to bits of ceramic breaking away from the manifold. I'm in Sydney and the best place I know is Comcoat at Granville NSW and a manifold will cost you upwards to $250.00.

Cheers, D

[Duncan]

don't space up the rer of the bonnet, that i s just a silly ricer fad.

the rear of the bonnet is a high pressure area so it acts as an intake not an exhaust for air. have a look where nascars run their airbox intake....bottom of the windscreen

[DJRIFT]

don't space up the rer of the bonnet, that i s just a silly ricer fad.

the rear of the bonnet is a high pressure area so it acts as an intake not an exhaust for air. have a look where nascars run their airbox intake....bottom of the windscreen

yea im onto that but the car we were running the bonnet on on the weekend had to have the bonnet spaced to fit over gay ass cooler piping.

previously on my own car ive never ran spacers.

[Ghostrider]

yea im onto that but the car we were running the bonnet on on the weekend had to have the bonnet spaced to fit over gay ass cooler piping.

previously on my own car ive never ran spacers.

Something I took particular notice of in Adelaide was the bonnet set up on the Winfield (Godzilla) GTR of Terry Ashwood's. It sure looks like it is spaced slightly UP at the front and I can only assume that's to get more cool air into the engine bay.

As Duncan said, spacing the rear is a rice fad and also give a great outlet for oil to the windscreen if the motor lets go and then you can't see sh!t.

Cheers, D

[260DET]

This is my modified old school Datsun 280ZXT bonnet, engine used to overheat with the standard bonnet but now runs cool and under bonnet temps are low. Exiting air out from the engine bay is the secret, not getting it in, thats the important thing and the reason why the factory NACA duct on the left was blocked off. The kickups in front of the vents help air extraction. I'm in the process of making a CF one with improved rear vents and no front vent, no pics of it yet.

[DJRIFT]

im happy that this thread has brought out some insight and different aspects of cooling.

so some say make the air go out the top. some say make it go out the bottom. i guess its just what ever works as a tried and tested setup.

[260DET]

im happy that this thread has brought out some insight and different aspects of cooling.

so some say make the air go out the top. some say make it go out the bottom. i guess its just what ever works as a tried and tested setup.

Hot air rises so its best to take advantage of that, the turbo on my car is directly under the left vent. Routing air out out underneath is undesirable in that it contributes to more drag and lift and can be blocked by an undertray or other obstacle. The only thing is that bonnet vents like mine seem unfashionable