PT Cruiser Forum  
Advertisements
       

Go Back   PT Cruiser Forum > 2.4L Turbo Forums > Turbo Performance

PT Cruiser Forum

Advertisements
Blow off valve - Questions

 
Like Tree5Likes

Reply
 
LinkBack Thread Tools Display Modes
  #21 (permalink)  
Old 28 Mar 2017, 11:22 am
Handy_Cruiser's Avatar
Obsessed Cruiser
 
Join Date: Oct 2013
Location: Arkansas
Posts: 8,492
Default Re: Blow off valve - Questions

Quote:
Originally Posted by OurPTGT View Post
I've been out of the game for some time but IIRC, the factory recirculating valve directs hot air back into the INTAKE flow not exhaust. Also IIRC, there was some concern early on about that redirected HOT air being mixed into the cool intake air.

EDIT: I should have read the entire thread first before posting
That's okay. The post needs correcting.

I suspect Rob is right as to why this turbo is designed this way. Let's look at the problem of heat with boost.

The theoretical outlet temperature for an industrial blower = Inlet temp. x (pressure in Bars)^0.286.

For our "quackilations", we will need our temperature in Kelvin. So 77 degree F becomes 298 degree Kevin.

So let's "quackilate" some boost temporatures using Arkansas 6th grade math.

Boost
psi------->Bars (atmospheres)...................................Bo ost Temp.

0--------->1.00…………………….. 298 K x (1.00 Bar)^0.286 = 298.0 K
5--------->1.34…………………….. 298 K x (1.34 Bar)^0.286 = 324.0 K
6--------->1.41…………………….. 298 K x (1.41 Bar)^0.286 = 328.6 K
7--------->1.48…………………….. 298 K x (1.48 Bar)^0.286 = 333.1 K
8--------->1.55…………………….. 298 K x (1.55 Bar)^0.286 = 337.4 K
9--------->1.62…………………….. 298 K x (1.62 Bar)^0.286 = 341.6 K
10-------->1.69…………………….. 298 K x (1.69 Bar)^0.286 = 345.7 K
11-------->1.76…………………….. 298 K x (1.76 Bar)^0.286 = 349.6 K
12-------->1.83…………………….. 298 K x (1.83 Bar)^0.286 = 353.5 K
13-------->1.90…………………….. 298 K x (1.9 0Bar)^0.286 = 357.2 K
14-------->1.97…………………….. 298 K x (1.97 Bar)^0.286 = 360.8 K
15-------->2.03…………………….. 298 K x (2.03 Bar)^0.286 = 364.4 K
16-------->2.10…………………….. 298 K x (2.10 Bar)^0.286 = 367.9 K


Boost
psi............................................... Temp in F

0---------------------->298.0 K = 77.0 degrees F
5---------------------->324.0 K = 123.8 degrees F
6---------------------->328.6 K = 132.2 degrees F
7---------------------->333.1 K = 140.2 degrees F
8---------------------->337.4 K = 148.0 degrees F
9---------------------->341.6 K = 155.5 degrees F Turbo Lite
10--------------------->345.7 K = 162.8 degrees F
11--------------------->349.6 K = 169.9 degrees F
12--------------------->353.5 K = 176.8 degrees F PT GT
13--------------------->357.2 K = 183.6 degrees F
14--------------------->360.8 K = 190.1 degrees F
15--------------------->364.4 K = 196.5 degrees F PT Stage 1
16--------------------->367.9 K = 202.8 degrees F



We could instead use the blower efficiency equation: Outlet Temp. = Inlet Temp. in K + [[Inlet Temp. in K x (-1 + (Outlet Pressure in psi /Inlet Pressure in psi)^0.263)] / Efficiency].

Let's say efficiency is 70%

Boost
psi................................Temp in F

0---------------------->77.0 degrees F
5---------------------->138.3 degrees F
6---------------------->149.2 degrees F
7---------------------->159.7 degrees F
8---------------------->169.8 degrees F
9---------------------->179.6 degrees F
10--------------------->189.1 degrees F
11--------------------->198.3 degrees F
12--------------------->207.2 degrees F
13--------------------->215.9 degrees F
14--------------------->224.4 degrees F
15--------------------->232.7 degrees F
16--------------------->240.8 degrees F




This is all my work. So please check my math.
__________________

Last edited by Handy_Cruiser; 28 Mar 2017 at 12:40 pm.
Reply With Quote
  #22 (permalink)  
Old 28 Mar 2017, 12:00 pm
rob302's Avatar
Dedicated Cruiser
 
Join Date: Jul 2016
Location: Darien, IL | Forest Park, IL
Posts: 2,510
Default Re: Blow off valve - Questions

but when air is rapidly decompressed, it cools. so the air that was heated when compressed would be expected to cool at the same rate when unpressurized back into the intake. adiabatic heating when compressed, adiabatic cooling when decompressed..

so any BOV benefit related to temperature and recirculated air is a neat thought, it may not be the actual case, or at least not to the effect you'd expect once science gets involved.

https://en.wikipedia.org/wiki/Adiabatic_process

i make signs though.. i could be wrong.
Reply With Quote
  #23 (permalink)  
Old 28 Mar 2017, 12:39 pm
Handy_Cruiser's Avatar
Obsessed Cruiser
 
Join Date: Oct 2013
Location: Arkansas
Posts: 8,492
Default Re: Blow off valve - Questions

Quote:
Originally Posted by rob302 View Post
but when air is rapidly decompressed, it cools. so the air that was heated when compressed would be expected to cool at the same rate when unpressurized back into the intake. adiabatic heating when compressed, adiabatic cooling when decompressed..

so any BOV benefit related to temperature and recirculated air is a neat thought, it may not be the actual case, or at least not to the effect you'd expect once science gets involved.

https://en.wikipedia.org/wiki/Adiabatic_process

i make signs though.. i could be wrong.

Signs or no signs, I still say you are smarter than the rest of us here.

If we knew the size of the opening back into the turbo intake side, we could calculate this to see what kind of expansion (and resulting temperature) we actually get.

When you consider that the throttle will be closed at this point and forward air flow will be reduced to whatever is metered by the idle air control valve, I wonder if the turbo bypass valve creates back flow in the air filter for at least a moment?
__________________

Last edited by Handy_Cruiser; 28 Mar 2017 at 01:01 pm.
Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
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 Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
blow off valve SuperGirl Tech & Performance Forum 24 25 Apr 2013 08:57 pm
Blow off valve. Turboguy85 Turbo Performance 6 03 Feb 2012 12:49 pm
blow off valve question reaper121 General Turbo Discussions 5 21 Feb 2009 05:12 pm
what is a blow off valve careyk General PT Cruiser Discussions 3 17 Apr 2008 02:23 pm
Stock blow off valve DMW General Turbo Discussions 8 12 May 2005 07:08 pm


All times are GMT -5. The time now is 08:58 am.




Powered by vBulletin® Version 3.8.2
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
LinkBacks Enabled by vBSEO 3.6.0 PL2 © 2011, Crawlability, Inc.
vB.Sponsors