Journey with Confidence RV GPS App RV Trip Planner RV LIFE Campground Reviews RV Maintenance Take a Speed Test Free 7 Day Trial ×
RV Trip Planning Discussions

Go Back   iRV2 Forums > MOTORHOME FORUMS > Class A Motorhome Discussions
Click Here to Login
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on iRV2
 
Thread Tools Search this Thread Display Modes
 
Old 10-14-2012, 08:45 AM   #29
Senior Member
 
336muffin's Avatar
 
Join Date: Apr 2011
Posts: 2,569
American Coach uses a roof mounted air intake with a air scoop very similar to the Kenworth design.
__________________
American Tradition 42R-Cadillac SRX Blue Ox Koni 5050XL MCD Scangauge D Samsung rf197
Fulltime since 2012
336muffin is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free!

iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 10-14-2012, 10:43 AM   #30
Senior Member
 
Join Date: Aug 2012
Posts: 390
watch your boost gauge. turbo boost goes with fuel and work load. pulling a hill with your foot in the throttle is one place you're going to pull max boost. but cruising on the flats, barley in the throttle, boost presure should be low if any. and this is where i'd look for increases. other wise i think the scoop would only help direct air to the intake track. this discussion is similar to everyone's idea on how to build small block cheys. rule of thumb was 1.5 or 1.6 rocker arms. then a fellow built a 350 running on gas and put in 1.8 rocker arms everyone said he's combination would not work. long story short he pulled 750hp on gas. now they make 2.1 rockers. iskenderian said their hydraulic cams were as agressive as one could go. comp cams kept bumping the designs up and iski bumped theirs. now we have the super mega cams.
wonderer1 is offline   Reply With Quote
Old 10-14-2012, 11:43 AM   #31
Senior Member
 
ardbark's Avatar
 
Monaco Owners Club
Join Date: Oct 2011
Location: Logan, Ut
Posts: 315
Quote:
Originally Posted by VanDiemen23 View Post
If the intent of the scoop is to get cooler, more dense air, then OK, but a WELL DESIGNED scoop doesn't see any positive pressure until about 50mph, and with a 70mph top end, the juice just isn't worth the squeeze from a "poor mans turbo" standpoint.

They work on racecars, 1/4 mile and otherwise, because the majority of the time is spent well above 50mph, and everything under the engine cover is hot as hell.

Sometime the scoop is just an efficient way to get the air turned 90 degrees into the induction system, and it doesn't provide pressure recovery at all.
Since I started this crazy thread, I guess I should chime back in.

My original thinking when I first postulated the idea of adding a scoop on my side intake was simply to insure there was always positive pressure at the filter intake. I guess, as Van Diemen wrote, I was thinking of it as "an efficient way to turn the air 90 degrees", thus avoiding a potential low pressure area around the intake vent slipstream (Bernoulli's principle). Maybe at our speeds Bernoulli doesn't apply, but I can demonstrate Bernoulli by gently blowing over the top of a piece of paper, far below a 60mph airstream.

I never invisioned a "ram air" scenario where the scoop actually added enough head pressure to affect the inductions system, too many restrictions between the atmosphere and the cylinder for a few extra pounds of pressure to make any difference. I actually hadn't thought of the air being any cooler or denser or whatever either, but since the intake is still on the side of the coach where it has always been I don't suppose the state of the ambient air would change.

I did like the idea of moving the intake to the roof area, and using that same system to vent heat after you stop. That seems clever. You get a cleaner air supply than the dusty road environment, and venting the heat past my bedroom is something I could fall in love with. On the downside there would also likely be more moisture available on the roof that could sneak into the intake, so one would need to watch out for that.

Great conversation, lots of good thoughts. Don't know that I will ever get to this project, but winter is coming uphere in the frozen tundra, so who knows
__________________
Its not the destination, its the journey
2003 FW Disco 39L chased by 2300 lbs of raging GEO Tracker
ardbark is offline   Reply With Quote
Old 10-14-2012, 11:57 AM   #32
Senior Member
 
ardbark's Avatar
 
Monaco Owners Club
Join Date: Oct 2011
Location: Logan, Ut
Posts: 315
Quote:
Originally Posted by wonderer1 View Post
watch your boost gauge. turbo boost goes with fuel and work load. pulling a hill with your foot in the throttle is one place you're going to pull max boost. but cruising on the flats, barley in the throttle, boost presure should be low if any.
I'd love to watch my boost guage but the damn thing quit working. A brand new ISSA Turbocator too (re:EXPENSIVE!). Just put it in this spring, lasted one trip. The pyro works fine but the boost, which I used to be able to bury at 30psi, now might move to 5psi under full throttle

I checked the plastic tube connections on both ends, they seem fine, so I've either got a nicked in the tube somewhere or a bad guage. Arghhh...
__________________
Its not the destination, its the journey
2003 FW Disco 39L chased by 2300 lbs of raging GEO Tracker
ardbark is offline   Reply With Quote
Old 10-14-2012, 12:38 PM   #33
Senior Member
 
Triker56's Avatar
 
Fleetwood Owners Club
Join Date: Jun 2009
Posts: 4,031
Quote:
Originally Posted by ardbark View Post
I'd love to watch my boost guage but the damn thing quit working. A brand new ISSA Turbocator too (re:EXPENSIVE!). Just put it in this spring, lasted one trip. The pyro works fine but the boost, which I used to be able to bury at 30psi, now might move to 5psi under full throttle
Maybe you should have gotten a Banks.
Mine will hit 32-33 PSI when needed.
__________________
99 Discovery 34Q ISB
2014 MKS AWD EcoBoost Toad
Fulltime Since "99"
Triker56 is offline   Reply With Quote
Old 10-14-2012, 12:47 PM   #34
Registered User
 
Vintage RV Owners Club
Gulf Streamers Club
Join Date: Oct 2010
Location: Indiana
Posts: 4,951
Faster air is lower pressure air.. you want to build pressure and lower the speed. As I said before, scoops dont work the way people in this thread are thinking.
Midniteoyl is offline   Reply With Quote
Old 10-14-2012, 01:14 PM   #35
Member
 
stich's Avatar
 
Monaco Owners Club
Join Date: Aug 2012
Posts: 86
My '98 Monaco Exec has the scoop on the roof moulded into the rear cap. Also has a side discharge fan on the right rear to vent hot air. Not sure if they still use this system anymore. Would be interested to see why, why not though.
stich is offline   Reply With Quote
Old 10-14-2012, 01:17 PM   #36
Senior Member
 
jauguston's Avatar
 
Join Date: Jul 2006
Location: Bellingham,WA
Posts: 973
Unless you have some kind of a performance programmer you are not going to have much luck trying to raise the boost. My Cat C-7 for example will get a maximum of 27 psi of boost. If I try to give it more-disable the wastegate-the ECM will just defuel it. I can watch the pyrometer and see it happen. EGT will climb as the boost and RPM increases and when it hits 27 psi the EGT drops. It will also defuel above 2200 rpm where maximum horsepower is rated. If I turn my MP-8 all the way up the boost will go to 30-31 psi before it defuels.

Jim
__________________
2005 Sportscoach Elite 40' C-7 350 Cat w/MP-8
Suzuki Samurai toad w/VW 1.6 turbo diesel
800w solar system
jauguston is offline   Reply With Quote
Old 10-14-2012, 05:17 PM   #37
Senior Member
 
Join Date: Aug 2012
Posts: 390
picking up air flow below 50mph is not exactually true. if you used a 4 ft dia. scoop feeding a 6" intake your going to increase flow a lot. but obviously you couldn't run one that big. lots of hp to pull one that big. but where is the line big enough to do some good and small enough not to cost hp. and yes look at some of the city busses. some have scoops on the roof. so i would check out the busses to see how they deal with the rain issue.
wonderer1 is offline   Reply With Quote
Old 10-14-2012, 06:43 PM   #38
Registered User
 
Vintage RV Owners Club
Gulf Streamers Club
Join Date: Oct 2010
Location: Indiana
Posts: 4,951
You'll only flow as much as the 6", maybe even less. You need to slow the air down. the 4' scoop to 6" pipe would speed it up.
Midniteoyl is offline   Reply With Quote
Old 10-23-2012, 06:27 AM   #39
Senior Member
 
TwelveVolt's Avatar
 
Join Date: Oct 2012
Posts: 1,115
I have never noticed anyone mention air temperature when reporting their MPG. Is there a difference between driving a desert highway on a summer day at 110F and driving the same road on a winter night at 40F? The engine intake air is colder and therefore more dense, but you are also trying to push the bus through denser air. Comments?

In practice, I assume many would also have their generator/AC running at 110F, thereby dropping the MPG.
TwelveVolt is offline   Reply With Quote
Old 10-23-2012, 07:06 AM   #40
Senior Member
 
vraines's Avatar
 
Join Date: Feb 2012
Posts: 715
The trick is to achieve cooler air, ie denser charge, in the intake system. If I remember, a 3 degree c reduction will yield nearly 1% increase in power. That is the purpose of the cooler in the turbo system. Tricks to do this are legendary, but that is a source of cheap power. The turbo heats the charge greatly, but a 1 degree decrease in air temp results in about the same reduction through the system including the EGT.
__________________
2007 Dutch Star 4320
2010 Mazda Miata 6 speed
Roadmaster tow
vraines is offline   Reply With Quote
Reply



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
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 Off
Pingbacks are Off
Refbacks are Off


» Featured Campgrounds

Reviews provided by


All times are GMT -6. The time now is 02:29 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.