Skyline Owners Forum banner

1 - 20 of 22 Posts

·
M's Factory
Joined
·
5,240 Posts
Discussion Starter #1
Ok I have been thinking about this for some time and I notice there has been a few theads about peopel looking to put in air dams etc.

I have put some thought to it and I have come up with the following idea if it is going to be done then it needs some thought even on a relatively simple thing.

Underbonnet heat is the enemy of any exposed under-bonnet air filter - remember, hot intake air can undo the potential benefits of reduced restriction. To get around this you need to fabricate (or get someone else to fabricate) a comprehensive heat shield. When we say 'comprehensive', it has to box the filter off, or - at least - enclose it with a perfect seal against the inner guard and bonnet. There can be nowhere left open for hot air to be drawn through.

Looking on some other boards and also listening and reading threads on here a lot of people use sponge rubber or C-section automotive edge trimming (this is the kind you see being used around door apertures) to make the seal against the bodywork. It's a neat idea.

While sealing the edge of the shield is ultra important, it is equally important that the shield is fabricated from a material that'll keep the under-bonnet heat on the 'other' side. Stainless steel is a traditional favourite here, but - really - the thicker and better insulator the divider is, the better.

Something I have heard is a guaranteed way of reducing under-bonnet heat transfer is to make the shield out of blank sheets of 'double layer heat management material' as used on the exhaust manifold of current Ford model cars. A section 760mm x 412mm can be bought for around 35-45 quid from various exhaust component wholesalers.

Mount the heat shield to the vehicle body using rivets or bolts
and nuts.

Put a nice cold air feed to the cone area which is now blocked off from heat and there you go , one cold air drawn in efficient air filter, this should become more noticeable in the hot weather.
 

·
SOC Logo Champ
Joined
·
602 Posts
Has anyone actually done this to thier car ? I have to say that I'm interested in the whole heat shielding area and the benefits of it.

If anyone has done any, have you noticed a difference, I can't imagine that the gains are major, but a worthwhile investment ?
 

·
M's Factory
Joined
·
5,240 Posts
Discussion Starter #3
no one has really done it over here, it is something I have looked into and its something I am going to be doing.

Im not sure how you can say the gains are not worth it. cost wise its not expensive, but however gaining "fresh air" rather than hot air is important in any engine, but especially in a turbo engine. If you reduce the charge intake temperature then you gain, always.

Try driving your car on a cold morning then a warm morning and see if you notice any difference.
 

·
Registered
Joined
·
119 Posts
hi mark i done that to my golf a while back all made out of aluminum worked well
 

·
SOC Logo Champ
Joined
·
602 Posts

·
M's Factory
Joined
·
5,240 Posts
Discussion Starter #6
excellent find mate. As I said it is something I am looking into and when i have some money to move around I will look at doing it over a weekend.
 

·
SOC Logo Champ
Joined
·
602 Posts
Reading some more of the threads on that board the difficultly comes in getting some Cold Air Induction to it. Some of the owners have cut an additional hole below the filter and run pvc piping to under the indicator.

Don't fancy cutting a hole there personally. I'm sure there must be enough space to run it up through the engine bay.
 

·
M's Factory
Joined
·
5,240 Posts
Discussion Starter #8
my thoughts were running a duct from the codl air ram in the front bumper to the air pod section, maybe two , one either side.
 

·
Registered
Joined
·
953 Posts
i have but some kind person torched back of car but if any one wants to se it its in peices is a lot better
 

·
Registered
Joined
·
2,433 Posts
Hmm... I'm halfway there with no headlight and a thermal resistant wrap on the pipework, and the difference is fantastic.

On my old Trans AM I had a cold air feed to the carbs......

It had the famous 'Shaker Scoop' on the top of the carbs, that protruded thru a HUGE hole in the bonnet, with an inlet at the rear, facing the windscreen.

On the latter models tho, the inlet was blocked off and air was fed thru a hose under the hood. Only way to get a 6.6 litre V8 thru the emissions/power laws in the US in 1979. I got a kit to re-activate it, and anytime over 50% throttle caused the flap to open and a 12" by 3" gap to be open to atmosphere. Small filter in it and whoosh! Cold air direct from atmosphere, outwith the hood, into the carbs. Thats what got me thinking of doing a cold partition on the skyline. The difference it made to the T/A was very impressive.

There is a LOT of info on the SDU forums in the 'Free horsepower' thread.

Its here I think:

http://forums.skylinesdownunder.co.nz/showthread.php?s=&threadid=3259&perpage=25&highlight=horsepower&pagenumber=1

There is a LOT of reading in there, but for those into cheap bang for bucks its a DAMN good thread. Lots of knowledge down there.
 

·
Free icecream
Joined
·
2,112 Posts
I would imagine it's also worthwhile doing as Jock's done and put some form of insulation on the intake pipework (and the exhaust too I guess). The pipe across the cam covers gets too hot to put your hand on so it must heat the incoming air.

Can someone explain to me how you can work out the profile for the edge of the partition so it follows the inner contours of the bonnet? I can't get my head round this at all!

I've got a sample of that aluminium sandwich stuff (2mm not 5mm
:( ) and i'll bring it to JAE today if anyone wants a look. *Moschops, you've left it a bit late to tell them*

Right, off to bed - dreaming of partitions...
 

·
Banned
Joined
·
852 Posts
I made up a barrier from a bit of plastic sheet, a couple of mm thick which goes from the wheel arch to the carbon filter at the radiator.

Under where my HKS filter is there is alread a hole which I am assuming was where the original intercooler pipework was, I have a GTR front mount intercooler on mine.

Through this hole I put a piece of plastic pipe which is a sweeping 90 degree bend and onto the end of that I fitted some hose which I tiewrapped to the intercooler pipework and stops at the mesh on my front bumper.

The pipe is a good snug fit and has a lip around it so when it's in placeit can't fall out. I put some silicone sealant around it just to make sure it stayed in place.

My theory is that when I'm moving the air will be forced up the pipe into the partition made by the bit of plastic and surrounding the air filter. I didn't put a cover over the filter because I wonted as much clearance around it as possible so that it isn't starved of air due to it's suface area being reduced.

I will take photo's if anyone wants to see what I've done and if you are interested I should be able to get a couple of bits of the pipe and hose from work so someone else could try it, hey it's free!

I don't know if I'm getting more power or not as the results would not show up on a dyno as it wouldn't be getting the cold air rammed into the compartment and I did it just after I got my new clutch fitted so I had been driving like an old git so when it got back up to the usual power the car felt awesome anyway, I have noticed that I'm getting less MPG so I reckon I must be getting a denser charge.:D :cool:
 

·
M's Factory
Joined
·
5,240 Posts
Discussion Starter #13
i doubt you will get more power on a dyno as its not ram air. + the bonnet is open on a dyno.

It is just soley to get cold air into the pod rather than warm air. There is some good points on this thread appearing.

Interesting on your old car Jock.
 

·
SOC Logo Champ
Joined
·
602 Posts
Stole this off another forum.

R33 GTSt Intake Temperature Tests
Recently I performed some intake temperature tests. They are not dead acurate but are atleast an indication of when heat soak is affecting your engine. I used some digital thremometers from jaycar for the tests.

The car: 1993 R33 GTSt, 3" turbo back exhaust, 8psi (stock) boost, stock intercooler, pod filter with cold air partition (95deg neoprene heat shield).

Ambient temperature: 17degC


1st Test: Cruising at 110km/h
Pod = 15deg
AFM = 15deg
Engine Bay = 35deg

2nd Test: Stuck in traffic (45km/h max.) (heat soak had set in)
Pod = 35deg
AFM = 37deg
Engine Bay = 55deg

3rd Test: On boost hill climb and high speeds
Pod = 14deg
AFM = 12deg
Engine Bay = 33deg

4th Test: Heat Soak
After pulling up at a set of lights from cruising at 110km/h, it took 3 minutes to reach full heat soak as shown in the 2nd test. It took 7 minutes of driving at 110km/h again to fully get rid of it.....

5th Test: After idle for 3 mins
Pod = 40deg
AFM = 43deg
Engine Bay = 60deg
 

·
M's Factory
Joined
·
5,240 Posts
Discussion Starter #16
confusing that.
 

·
Registered
Joined
·
13 Posts
This is my first post on this site, so I'll start by saying a huge HELLO to anyone that knows me from the other place, especially to tigger.

I read this thread with interest as I am also concerned about the amout of heat under the bonnet, and have spent some time studying how the various race teams have developed ways of getting rid. The heat not only affects the filters, but the whole engine. Venting the bonnet towards the back will assist by letting some of the hot air escape, but I don't think this is adequate.

So I have bought myself another (spare ) bonnet so that I can mess about installing a central louvred vent with a slight lip towards the front. This will increase the effect of a low pressure area thus sucking air out of the bonnet and improving airflow through the intercooler and rad.
I am planning a small intake immediately above the filters with a curved assembly underneath to blast more cold air directly onto the filters.

Prototype pic attached
 

Attachments

·
Super Moderator
Joined
·
9,426 Posts
Hi John! nice to see you here...car is looking wicked mate!

With the venting, would there be any probs with any water getting onto the air filters at all...I guess you just have to keep the vents away from them really....?
 

·
Registered
Joined
·
13 Posts
Hiya Tigger, but I think I'll start calling you Fred from now on.

That pic above is just me tinkering with graphics, you know what I'm like when I get me crayons out!

I had one or the most boring rides back from Elvington...In my neigbours Volvo. Its a long story but basically he just drives soooo slooooow. Took us 4.5 hours to cover 120 miles and his jokes go on for about 20 minutes each. Other than that he's a nice bloke.

Water in the vents....yes I have considered that but not quite sure yet how I'm going to stop things getting soaked. Maybe a tiny umbrella over the filters and an anorak over the top of the engine. Any other stupid suggestions would be welcomed.

John
 
1 - 20 of 22 Posts
Top