Go Back   986 Forum - for Porsche Boxster & Cayman Owners > Porsche Boxster & Cayman Forums > Performance and Technical chat

Reply
 
LinkBack Thread Tools Display Modes
Old 07-27-2013, 04:26 PM   #1
Registered User
 
Brad Roberts's Avatar
 
Join Date: Aug 2004
Location: Alta Loma, CA
Posts: 1,334
How we drop intake air temp 40+deg.

Compared to a Z06 Vette, the Boxster's and Cayman's have a HORRIBLE intake air temp issue!!

The issue: the engine heat is trapped in the "box" called the engine compartment. Intake air temps on a 996/997/GT3/Turbo are way way lower!! They have clean air flow moving about in the engine compartment (think rear wing/spoiler)

How do we *help* kill off some of this heat being ingested into the engine??

We wrap the airbox and air intake tubes in heat reflective gold foil!! We also wrap the intake!!

Took about 4 hours to wrap this 987 air box for a race car we are building.



__________________
Engine Builds, Transmission Builds, Engine Conversions, Suspension Installs, Suspension Tuning, Driver Coaching, Data Acquisition, Video, SCCA/PCA/POC/NASA/GRAND AM/ALMS.
We have worked with amateur and professional drivers for over 26 years. In house machinist, In house fabrication. Our cars, our parts, our engines, our transmission's run nationwide at events every weekend. We work side by side with industry names developing parts.
Brad Roberts is offline   Reply With Quote
Old 07-27-2013, 05:30 PM   #2
Registered User
 
Join Date: May 2010
Location: UK
Posts: 874
What are the numbers for this then? How much does the temp drop with the foil?

My uninformed George Dubbya Gut tells me the plastic box doesn't conduct heat terribly well and the airflow will be significant at the high revs where this actually matters and the air is being drawn directly from outside so.....
__________________
Manual '00 3.2 S Arctic Silver
pothole is offline   Reply With Quote
Old 07-27-2013, 07:25 PM   #3
Registered User
 
Brad Roberts's Avatar
 
Join Date: Aug 2004
Location: Alta Loma, CA
Posts: 1,334
We regularly see temps 60+ degrees higher than ambient.

We measure/data log with the mass air flow meter that mounts just a couple of inches away from the round opening you see.

Use the gold foil? and the air intake temps drop.

The air box is just one part. We wrap the intake also (but this is not logged) so.. the mass airflow sensor is reading the air coming through the air box/snorkel.

The intake absorbs a LOT more heat do to the block being 6-8 inches below it.
__________________
Engine Builds, Transmission Builds, Engine Conversions, Suspension Installs, Suspension Tuning, Driver Coaching, Data Acquisition, Video, SCCA/PCA/POC/NASA/GRAND AM/ALMS.
We have worked with amateur and professional drivers for over 26 years. In house machinist, In house fabrication. Our cars, our parts, our engines, our transmission's run nationwide at events every weekend. We work side by side with industry names developing parts.
Brad Roberts is offline   Reply With Quote
Old 07-27-2013, 07:34 PM   #4
Registered User
 
Brad Roberts's Avatar
 
Join Date: Aug 2004
Location: Alta Loma, CA
Posts: 1,334
I've worked on these in the past.. GM engineers told me about an entire team of people dedicated to air intake temp control on the Corvettes. They asked me about the Porsches.. I didn't know the answer.. then I data logged the info and got back to them. They told me what they do to get the intake temp as close as they can to ambient. I was not able to achieve ambient in the Boxster or Caymans.

I was told this 10+ years ago now.. This isn't the first air box I have done.

__________________
Engine Builds, Transmission Builds, Engine Conversions, Suspension Installs, Suspension Tuning, Driver Coaching, Data Acquisition, Video, SCCA/PCA/POC/NASA/GRAND AM/ALMS.
We have worked with amateur and professional drivers for over 26 years. In house machinist, In house fabrication. Our cars, our parts, our engines, our transmission's run nationwide at events every weekend. We work side by side with industry names developing parts.
Brad Roberts is offline   Reply With Quote
Old 07-27-2013, 08:01 PM   #5
Rennzenn
 
j.fro's Avatar
 
Join Date: Feb 2005
Location: Virginia
Posts: 1,355
Garage
I moved my filter and box out of the engine bay. Since I don't have a top or sound deadening, I was able to put the filter where the "tunnel" used to be and build a box around it.
j.fro is offline   Reply With Quote
Old 07-27-2013, 08:03 PM   #6
Rennzenn
 
j.fro's Avatar
 
Join Date: Feb 2005
Location: Virginia
Posts: 1,355
Garage
I moved my filter and box out of the engine bay. Since I don't have a top or sound deadening, I was able to put the filter where the "tunnel" used to be and build a box around it.
j.fro is offline   Reply With Quote
Old 07-27-2013, 09:18 PM   #7
Registered User
 
Brad Roberts's Avatar
 
Join Date: Aug 2004
Location: Alta Loma, CA
Posts: 1,334
Good job!!

I had some good idea's on different air box system, but the owner of the car poo-poo'd the idea.

Funny part? I suggested to him we take air from both sides (2 years ago) The new 981's take air from both sides.. LOL
__________________
Engine Builds, Transmission Builds, Engine Conversions, Suspension Installs, Suspension Tuning, Driver Coaching, Data Acquisition, Video, SCCA/PCA/POC/NASA/GRAND AM/ALMS.
We have worked with amateur and professional drivers for over 26 years. In house machinist, In house fabrication. Our cars, our parts, our engines, our transmission's run nationwide at events every weekend. We work side by side with industry names developing parts.
Brad Roberts is offline   Reply With Quote
Old 07-28-2013, 02:58 AM   #8
Rennzenn
 
j.fro's Avatar
 
Join Date: Feb 2005
Location: Virginia
Posts: 1,355
Garage
I thought about going dual, but is there any cooling issue ditching the fan on the passenger side?
j.fro is offline   Reply With Quote
Old 07-28-2013, 12:26 PM   #9
Registered User
 
Join Date: Dec 2006
Location: Santa Barbara, CA
Posts: 308
what is the mechanism? body temperature of the intake plumbing causing the intake air to get warm? is this is the case, slowing down the air in the intake pipe before the throttle body by putting 2nd inlet plumbing would seem to make the air warm up even more?
am I all wet???
sb01box is offline   Reply With Quote
Old 07-28-2013, 01:33 PM   #10
Registered User
 
Johnny Danger's Avatar
 
Join Date: Nov 2008
Location: Massachusetts
Posts: 4,809
Garage
Does something like the EVO high flow air intake improve this situation ?
Attached Images
 
__________________
Don't worry I've got the microfilm.
Johnny Danger is offline   Reply With Quote
Old 07-28-2013, 03:22 PM   #11
jakesbox
 
trimer's Avatar
 
Join Date: Apr 2012
Location: Charlotte NC
Posts: 759
Quote:
Originally Posted by Johnny Danger View Post
Does something like the EVO high flow air intake improve this situation ?
This is the set up I have on my car...don't know what it does though!
__________________
2003 996 Twin Turbo X50, PCCB, polar silver / 2004 996 Carerra Cabriolet, midnight blue, cinnamon leather, IMS Pro / 2003 Artic Silver Boxster - Short Throw Shift, IMS Upgrade, Carerra Light Wheels, De-Snorked with Evoms Cold Air Intake, GHL Exhaust (Sold) / 2002 Seal Grey Boxster - Fabspeed Exhaust, Black powder coated wheels, Porsche stripes (Sold) / 2 -1957 356 A Speedsters (signal red and seal grey) (Sold) / 1989 944 Turbo (m030 S options)
trimer is offline   Reply With Quote
Old 07-28-2013, 09:02 PM   #12
Registered User
 
jb92563's Avatar
 
Join Date: Apr 2012
Location: Riverside, CA
Posts: 1,663
I recall from thermo dynamics theory that reducing pressure reduces temp and occurs at the narrow part of a venturi where the airspeed velocity is high.

Perhaps some venturi shaped intake could help?

I have that problem in my aircraft where if the intake venturi carb gets too cold it can form ice and needs carb heat to prevent that in my 1400cc VW engine.
__________________
"It broke because it wants to be Upgraded "
2012 Porsche Performance Driving School - SanDiego region
2001 Boxster S, Top Speed muffler, (Fred's) Mini Morimotto Projectors, Tarret UDP,
Short Shifter, Touch Screen Dual Din Radio, 03 4 Bow glass Top (DD & Auto-X since May 17,2012)
jb92563 is offline   Reply With Quote
Old 07-29-2013, 04:26 AM   #13
Registered User
 
Join Date: Aug 2005
Location: Sanford NC
Posts: 2,315
Given that the air intake is taken from the side of the car well above the heated pavement and passes relatively quickly through the intake I would have thought that there would be little heat transfer.

How were the measurements taken to confirm the effectiveness of this approach?
mikefocke is offline   Reply With Quote
Old 07-29-2013, 05:13 AM   #14
Registered User
 
Join Date: Jun 2013
Location: Socal
Posts: 560
You are ghinking about it the wrong way ...
the heat transfer is not from warm air going in , but from the heat of the engine transferring out ...
Ian c is offline   Reply With Quote
Old 07-29-2013, 11:33 AM   #15
Registered User
 
jb92563's Avatar
 
Join Date: Apr 2012
Location: Riverside, CA
Posts: 1,663
Thats a good point Ian, its radiant heat therefore blowing air into the engine compartment would not have a huge effect, and so the foil is supposed to reflect the "radiation" and prevent the walls of the airbox from getting as hot.

What about those muffler heat tapes/blankets, those are also designed to prevent heat absorbtion and can further insulate the airbox.

I suppose a combination of all these things including more air blowing out the "conventive" heat as well in the engine compartment should all help.
__________________
"It broke because it wants to be Upgraded "
2012 Porsche Performance Driving School - SanDiego region
2001 Boxster S, Top Speed muffler, (Fred's) Mini Morimotto Projectors, Tarret UDP,
Short Shifter, Touch Screen Dual Din Radio, 03 4 Bow glass Top (DD & Auto-X since May 17,2012)
jb92563 is offline   Reply With Quote
Old 07-29-2013, 11:56 AM   #16
Registered User
 
Join Date: Jun 2013
Location: Socal
Posts: 560
Exhaust wrap would work but weighs a lot more than gold foil
Ian c is offline   Reply With Quote
Old 07-29-2013, 12:40 PM   #17
Registered User
 
Join Date: Dec 2006
Location: Santa Barbara, CA
Posts: 308
I believe that wrapping the plastic does reduce the absorption of radiated heat and therefore the increase in the plastic body temperature will be less.
google plastic for auto and got DuPont zitel PA66 is one of such plastic.
can't find thermal conductivity nor thermal emission (absorption) coefficient.
as a norm, plastics do not have strong thermal conductivity and emission/absorption.
so i'm wondering how much of an influence does the manifold have.
sb01box is offline   Reply With Quote
Old 07-29-2013, 12:47 PM   #18
Track rat
 
Topless's Avatar
 
Join Date: Nov 2006
Location: Cucamonga CA
Posts: 3,640
Garage
I gotta go with Mike on this. I need to see some before and after hard data because it goes against what I understand about radiant heat transfer.

For comparison, 40 degrees is the equivalent heat rise across a highly efficient copper heat exchanger inside a 400,000 BTU gas fired water heater with 1,500 degree F. flames lapping at the copper coils. Water velocity is also spread out and slowed down to maximize contact time and heat rise. That is a very different environment than a Boxster intake.

My initial engineering thoughts:

- The plastic box and intake are poor conductors of heat.
- Intake air velocity is pretty high so not much heat-absorbing contact time.
- High velocity air is a relatively poor conductor of radiant heat.

Best guess: Little if any measurable intake radiant heat rise. This is easily tested with a temp probe at the intake grill for ambient and another just ahead of the throttle body. Compare results.
__________________
2009 Cayman 2.9L PDK (with a few tweaks)
PCA-GPX Chief Driving Instructor

Last edited by Topless; 07-29-2013 at 12:52 PM.
Topless is offline   Reply With Quote
Old 07-29-2013, 01:51 PM   #19
Registered User
 
The Radium King's Avatar
 
Join Date: Apr 2010
Location: Canada
Posts: 2,873
iirc there is an intake air temp sensor; ecu uses it to revise fuel trims. it's mounted on one of the intake plenums. you can log the data with your durametric. more likely the wires on the sensor heat and affect the sensor reading.
The Radium King is offline   Reply With Quote
Old 07-29-2013, 04:07 PM   #20
Registered User
 
Join Date: Aug 2005
Location: Sanford NC
Posts: 2,315
Well of course I may be wrong

But given that the air outside is liable to be lots less hot than the air inside the engine compartment and given that the air is passing quickly through the intake plumbing which should keep the plastic cool (except after the car has just been shut off when the radiated heat would not be countered by the incoming cooled air until the car had been running for a while) ...

I still am curious how you measured it as 40 degrees cooler after wrapping? Under what conditions were the measurements taken (was the engine compartment cover shut, how long had the engine been running and were the measurement taken with airflow going on because the car was moving)? And where were the measurement points?

I'm the resident skeptic and old enough to remember "trust but verify".
mikefocke is offline   Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -8. The time now is 01:35 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Content Relevant URLs by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page