Under bonnet temperatures and induction

J

Jevo

Active Member
Messages
53
Having had a bored 10 minutes this afternoon and still trying to decide on what is the best way forward re induction I thought I would check what the under bonnet temperatures were in various places on my DC5.

I checked 3 places at 3 speeds (40, 60 and 70mph)...

1) outside the bonnet right in front of the front grill

2) just behind the front grill where a Mugen CAI would pick air up

3) at the back of the engine bay where a K&N or Blitz would pick the air up

The results were probably as expected... bearing in mind its overcast outside and about 25c.

The difference between the outside of the front grill and the point were a Mugen CAI would pick the air up is 6c at 40mph i.e the outside air temp hitting the grill was 22.5c and by the time it had crossed the radiator to the Mugen pick up point it was 28.3c. I attribute most of this down to the warm air seeping from the radiator.

At 70mph this difference drops to about 3c i.e. front grill temp was 23.6c and the Mugen pick up point was 26.6c

However, when considering the rear of the engine bay pick up point as opposed the the Mugen area pick up the difference gets bigger. At 40mph the Mugen pick up point is 28.3c but the area at the back of the engine bay is 33.9c and at 70mph 26.6c as opposed to 32.9c.

The conclusion therefore is that the coolest air is as it hits the bonnet whilst the warmest is under the bonnet at the back of the engine bay.

This quick experiment does not take into account pockets of warm or cool air as you drive down the motorway or the pressure of the air hitting the different areas under the bonnet.

This in no way says 1 filter is better than another just that the coolest air is where it is forced through the front grill and in theory this would be the most dense air and better for more power.

Jevo
 
M

MJ Type-R

Advanced member
Messages
1,578
Hi m8,

I agree with you :lol:

The back of the engine will be the hotest part, as on new Honda's this is were the exhuast manifold is, this is so that the CAT gets to operating temp quickly, also hence why they are very compack manifolds now compared to previous car generations (DC2, EK9 etc) :shock:

Another trick I have seen with the OEM air box (this was on a DC5 in Singapore) is that the underside and feed pipe was raped in reflective foil, like the stuff you put behind radiators. I think this may help keep the intake temp down, you could try this with the mugen air box as well :)

Another thing to have a look at, at the top of the K20A engine next to the air box you have a rubber tube that connects one to each other. This basically means that you are allowing hot air to reciprocate back in (this air is usually very slightly oily as well). On the Euro EP3 you can disconnect this pipe and either feed to a oil catch tank or have a small filter on it, then on the air box use a simple rubber cap to plug the whole and all will work well (I have done this on my previous car with my induction kit and worked very well)

Final thing, I'm going to work on this. I know how its done on a S2K, but not sure currently on a K20A engine. If you look at air inlet manifold, yoy will find that there is engine cool feeds, basically engine coolant runs through the air inlet manifold, now if I'm wrong dosn't this heat the air going into the engine :? . I know that on the S2K it's possible to bypass this, and it does make a noticiable difference when you touch the manifold.

Just me rambling on

Mike
 
J

Jevo

Active Member
Messages
53
Mike,

Firstly welcome.. glad you finally arrived !!!

Following on from what you have said the more i think and talk to people about it the more i think the Mugen or the stock box works.

Spent some quality time with a TOP quality tuner and engine builder today (you know who you are if you're reading this) and he had exactly the same view that the open filters at the back of the engine would suck in less dense hot air...

Suggested possibly running a feed pipe from under the car to the Mugen box but that has the issue that it may suck in un-wanted water with the UK's great weather !!

But then he suggested I replace my front grill with an aluminium scoop feeding air straight to the the air box (a la Mugen bumper but without replacing the bumper).... and (by coincidence) covering the feeder pipe and box with a reflective covering or carbon...

Seems there is method in the madness....

Jevo
 
M

MJ Type-R

Advanced member
Messages
1,578
Hi m8,

Great minds think a like :D

You mentioned a scoop to replace or go behind the grill, well thats just like the Syncro Air box of of last years cars (the box is fully carbon fibre and has a large panel filter inside). Have a look at the pic below, sorry its not the best one I had, just can't find them !!! (woops)

http://uk.f2.pg.photos.yahoo.com/bc/mik ... %26.view=t

Hope this is of use and gives people ideas

Mike :wink:
 
J

Jevo

Active Member
Messages
53
Thats a Huge airbox...

Cant quite see where it pics the cold air up from though.... is it behind the grill ???

Jevo
 
M

MJ Type-R

Advanced member
Messages
1,578
Yes it does pick up air from behind the grill, and yes its very big !!!!

Thing with race cars is that you can move the bits around the car ie, the bat is relocated to inside the car etc

Mike
 
Unnamed_warrior

Unnamed_warrior

Advanced Member
Messages
630
Mate that looks like you have a dead whale in your bonnet...

How does it get over (under) through the RAD..

On the DC5's we have a rad infront of the grill.. so how did you manage to get your scoop to get cold air front the grill..

I have an Mugen box and my vent (scoop) is fixed right behind the rad so all I am getting is hot air from the rad going into the induction kit..
 
S

SJ_Skyline

Site Admin
Messages
838
CF Bonnet with a top mounted mini-scoop (like the scooby) forcing cold air down on a standard K&N cone...... :wink:

ok, I have not done it yet but got to be worth a try :wink:

Rich
 
T

Type R - Matt

Advanced Member
Messages
216
I reckon you need to use a system similar to the Gruppe M, so that you get a Ram affect, if you cut some of the plastic away from below the NSF window, you can fit an air duct, into a C/F/fibre glass box with a cylinder Air filter. This is what Kenny has done.

I can't understand why no one is copying that idea, as they would sell loads, the Gruppe M doesnt sell as it is too much £'s.
 
I

ITR489

New Member
Messages
2
I have the mugen CAI installed but dont have the mugen bumper for that air scope so I rip out the front grill, i think with the front grill rip out it sucked in more colder air.
 
R

red_DC5R

New Member
Messages
3
Hey Jevo,

Ever taken air temp measurements towards the open wheel well (on the right side when your facing the engine bay)? This is where the ARC induction box takes its cold air from. I think this might be even cooler than on top of the radiator..
 
J

Jevo

Active Member
Messages
53
Red DC5..

If you mean towards the back of the engine bay on the right as you look at the car yep i did there.. similar place to where a HKS filter would sit.. and if i remember correctly it wasnt that great... still hold that the best place is somewhere where it is forced in at the front of the car..

If i'm talking about the wrong place let me know...

Jevo
 
R

red_DC5R

New Member
Messages
3
Yeah thats the area Im talking about.
Its just that Im deciding whether to go for ARC induction box or mugen - and I have stock front bumper (won't be upgrading) so Im not sure that I'll be getting the most out of the mugen...
Anybody on this forum had any experience (or know of anybody) with the ARC induction box for the DC5?
 
T

Type R - Matt

Advanced Member
Messages
216
general concenous on CAI for the DC5 is the standard set up is best, and you will only gain power/torque from further mods.
 
T

Trung

Advanced Member
Messages
597
Have any of you seen the GruppeM CF ram charger for DC5?
If the set up is similar to EP3 then it maybe worth considering over ARC and Mugen?!?

EP3:
 
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