Omega Owners Forum

Please login or register.

Login with username, password and session length
Advanced search  

News:

Search the maintenance guides for answers to 99.999% of Omega questions

Pages: [1] 2  All   Go Down

Author Topic: Why do other cars not have multi rams or dual rams  (Read 1478 times)

0 Members and 1 Guest are viewing this topic.

geoffr70

  • Omega Baron
  • *****
  • Offline Offline
  • Gender: Male
  • Sunderland
  • Posts: 2665
  • Boobies
    • F/L 3.0 Elite, 3.0 MV6
    • View Profile
Why do other cars not have multi rams or dual rams
« on: 28 December 2010, 20:32:57 »
I think I'm right in my understanding of multi rams.

In brief, a manipulation of the air flow so that it is narrow and restricted at low revs and idle, then wide and unrestricted at full throttle and high revs, so that at any point in the rev range the flow of air is fast so that more torque can be generated. Or something along those lines.

I know that the multi rams are meant to smoothen the torque curve, well I've checked the operation of mine, but at 4100 rpm it seems to take off.

Anyway to the point. Why don't the majority of other cars have multi rams? Anyone know?

Thanks
Logged
TC and BnQ Trade holder.
I'll out pull you with my caravan!
V6 locking kit available locally, with deposit.

Kevin Wood

  • Global Moderator
  • *****
  • Offline Offline
  • Gender: Male
  • Alton, Hampshire
  • Posts: 36422
    • Jaguar XE 25t, Westfield
    • View Profile
Re: Why do other cars not have multi rams or dual rams
« Reply #1 on: 29 December 2010, 00:27:36 »
It's  more about keeping the intake system near resonance over a wide range of speeds. At lower RPM an engine makes better torque when fed from a long intake duct. At higher RPM you need a shorter duct for best results. Any engine will have surges and flat spots due to resonances in the intake and exhaust system and making the intake system variable is a good way of moving these resonances around as the engine accelerates, so they can be positioned to cancel each other out and give a flat torque delivery.

It, or something similar, is probably used on more engines than you realise.  ;) http://en.wikipedia.org/wiki/Variable_length_intake_manifold

Kevin
Logged
Tech2 services currently available. See TheBoy's price list: http://theboy.omegaowners.com/

wakeyomega

  • Intermediate Member
  • ***
  • Offline Offline
  • Gender: Male
  • Wakefield
  • Posts: 450
    • View Profile
Re: Why do other cars not have multi rams or dual rams
« Reply #2 on: 29 December 2010, 09:52:12 »
Nice wiki find Kevin, I'd always wondered what the theory was behind the variable inlet.
Logged
Remember, if you ever need a helping hand, you'll find one at the end of your arm

geoffr70

  • Omega Baron
  • *****
  • Offline Offline
  • Gender: Male
  • Sunderland
  • Posts: 2665
  • Boobies
    • F/L 3.0 Elite, 3.0 MV6
    • View Profile
Re: Why do other cars not have multi rams or dual rams
« Reply #3 on: 29 December 2010, 10:21:14 »
That's an interesting read, thanks for that.
Logged
TC and BnQ Trade holder.
I'll out pull you with my caravan!
V6 locking kit available locally, with deposit.

Chris_H

  • Omega Knight
  • *****
  • Offline Offline
  • Gender: Male
  • E London/Essex UK
  • Posts: 1716
    • Jag XF Portfolio S 3.0D
    • View Profile
Re: Why do other cars not have multi rams or dual rams
« Reply #4 on: 29 December 2010, 10:57:16 »
Quote
I think I'm right in my understanding of multi rams.

In brief, a manipulation of the air flow so that it is narrow and restricted at low revs and idle, then wide and unrestricted at full throttle and high revs, so that at any point in the rev range the flow of air is fast so that more torque can be generated. Or something along those lines.

I know that the multi rams are meant to smoothen the torque curve, well I've checked the operation of mine, but at 4100 rpm it seems to take off.

Anyway to the point. Why don't the majority of other cars have multi rams? Anyone know?

Thanks
I think the simple answer to your question is cost and complexity.

There are a vast number of tricks that can be done to improve i.c. engines and steering, brakes, transmissions.  But only enthusiasts will buy them and most manufacturers have to look to the mass market.

In the case of multi-rams, they are only really useful on naturally aspirated engines and they have turbos and superchargers looking over their shoulders as soon as they get too complicated.
« Last Edit: 29 December 2010, 10:59:43 by ChrisH174 »
Logged
First Vauxhall - PABX Cresta; Previous, previous Vauxhall - 3.0 12v Senator CD; Previous Vauxhall Omega Elite 3.0V6 Saloon Auto

Martin_1962

  • Guest
Re: Why do other cars not have multi rams or dual rams
« Reply #5 on: 29 December 2010, 11:12:41 »
Quite a few cars do have variable inlets
Logged

hoofing it

  • Omega Knight
  • *****
  • Offline Offline
  • Gender: Male
  • Posts: 1556
    • View Profile
Re: Why do other cars not have multi rams or dual rams
« Reply #6 on: 29 December 2010, 15:09:21 »
Quote
Quite a few cars do have variable inlets
12 valve senny didn't pitty though
Logged

Omegatoy

  • Omega Baron
  • *****
  • Offline Offline
  • UK
  • Posts: 3688
    • View Profile
Re: Why do other cars not have multi rams or dual rams
« Reply #7 on: 29 December 2010, 18:58:48 »
Quote
Quote
Quite a few cars do have variable inlets
12 valve senny didn't pitty though


2.6 12 valve did!!!
Logged

geoffr70

  • Omega Baron
  • *****
  • Offline Offline
  • Gender: Male
  • Sunderland
  • Posts: 2665
  • Boobies
    • F/L 3.0 Elite, 3.0 MV6
    • View Profile
Re: Why do other cars not have multi rams or dual rams
« Reply #8 on: 29 December 2010, 19:28:58 »
Quote
Quote
Quite a few cars do have variable inlets
12 valve senny didn't pitty though

If I remember rightly it did. I've had a 12 and 24 valve senny. The sennys had dual ram

Both 3 litre though. My dad had a 2.5 12v, I can't remember if that had dual ram or not.
« Last Edit: 29 December 2010, 20:26:07 by geoffr70 »
Logged
TC and BnQ Trade holder.
I'll out pull you with my caravan!
V6 locking kit available locally, with deposit.

Marks DTM Calib

  • Administrator
  • *****
  • Offline Offline
  • Gender: Male
  • West Bridgford
  • Posts: 34026
  • Git!
    • View Profile
Re: Why do other cars not have multi rams or dual rams
« Reply #9 on: 29 December 2010, 21:08:28 »
Loads of engines have variable inlet manifolds.....inlcuidng diesels!
Logged

geoffr70

  • Omega Baron
  • *****
  • Offline Offline
  • Gender: Male
  • Sunderland
  • Posts: 2665
  • Boobies
    • F/L 3.0 Elite, 3.0 MV6
    • View Profile
Re: Why do other cars not have multi rams or dual rams
« Reply #10 on: 29 December 2010, 21:58:55 »
Quote
Loads of engines have variable inlet manifolds.....inlcuidng diesels!

That's interesting, I certainly didn't know that diesels did!

I take it having a variable inlet on a charged engine wouldn't be useful then?
Logged
TC and BnQ Trade holder.
I'll out pull you with my caravan!
V6 locking kit available locally, with deposit.

hotel21

  • Administrator
  • *****
  • Offline Offline
  • Gender: Male
  • The Kingdom of Fife
  • Posts: 13021
    • View Profile
Re: Why do other cars not have multi rams or dual rams
« Reply #11 on: 29 December 2010, 22:03:06 »
Logged

geoffr70

  • Omega Baron
  • *****
  • Offline Offline
  • Gender: Male
  • Sunderland
  • Posts: 2665
  • Boobies
    • F/L 3.0 Elite, 3.0 MV6
    • View Profile
Re: Why do other cars not have multi rams or dual rams
« Reply #12 on: 29 December 2010, 22:10:38 »
Logged
TC and BnQ Trade holder.
I'll out pull you with my caravan!
V6 locking kit available locally, with deposit.

Marks DTM Calib

  • Administrator
  • *****
  • Offline Offline
  • Gender: Male
  • West Bridgford
  • Posts: 34026
  • Git!
    • View Profile
Re: Why do other cars not have multi rams or dual rams
« Reply #13 on: 30 December 2010, 17:09:55 »
Quote
Quote
Loads of engines have variable inlet manifolds.....inlcuidng diesels!

That's interesting, I certainly didn't know that diesels did!

I take it having a variable inlet on a charged engine wouldn't be useful then?

Yep, its basicaly what the swirl flaps do on the multivalve diesel engines.
Logged

TheBoy

  • Administrator
  • *****
  • Offline Offline
  • Gender: Male
  • Brackley, Northants
  • Posts: 107076
  • I Like Lockdown
    • Whatever Starts
    • View Profile
Re: Why do other cars not have multi rams or dual rams
« Reply #14 on: 30 December 2010, 17:29:33 »
Quote
Quote
Quote
Loads of engines have variable inlet manifolds.....inlcuidng diesels!

That's interesting, I certainly didn't know that diesels did!

I take it having a variable inlet on a charged engine wouldn't be useful then?

Yep, its basicaly what the swirl flaps do on the multivalve diesel engines.
When they actually stay attached to the rod :P
Logged
Grumpy old man
Pages: [1] 2  All   Go Up
« previous next »
 

Page created in 0.011 seconds with 16 queries.