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mark3
mark broad

(3 posts)

Registered:
12/09/2008 05:53PM

Main British Car:


R/R 4.6 V8 going s/density?
Posted by: mark3
Date: December 10, 2008 03:08PM

Hello guys, im new..i have a nice 4.6 V8 only 15k old in my 1996 R/Rover which i owned for nearly 4 years but only just found this web site!!

Im interested im removing the afm permanantly and hoped i may find some info to help me in my quest, i just dont like amfs and wana go speed density.
I have done this on my 88 Supra 3.0i turbo with fantastic results and throtle responce to boot.....would be nice to do it to the R/Rover too, although i have been told it wont be such an improvement as the Supra it should still be improved, and no afm, yeh!
The Range Rover has a few mods, nothing silly but they make a nice difference and speed density or MAP would be the icing on the cake, an interesting project to run along side all the others, lol...sadly i cant afford a standalone ecu though!

the Supra is quite a beast but i guess its not the thing to show here on british V8's lol, its neither british or V8! (unless asked of course, lol)

Any how hello everyone, tis nice to meet you....

il now wait to be told im on the wrong place, lol.....



Edited 2 time(s). Last edit at 12/10/2008 03:23PM by mark3.


Moderator
Curtis Jacobson
Portland Oregon
(4576 posts)

Registered:
10/12/2007 02:16AM

Main British Car:
71 MGBGT, Buick 215

authors avatar
Re: R/R 4.6 V8 going s/density?
Posted by: Moderator
Date: December 10, 2008 03:37PM

Mark - you're in the RIGHT PLACE. Welcome to the BritishV8 forum!

Unfortunately, your message was in the wrong sub-forum ("Other British Cars") so I've moved it to our "Engine" section where hopefully you'll get more and better response.


mark3
mark broad

(3 posts)

Registered:
12/09/2008 05:53PM

Main British Car:


Re: R/R 4.6 V8 going s/density?
Posted by: mark3
Date: December 10, 2008 04:05PM

Moderator Wrote:
-------------------------------------------------------
> Mark - you're in the RIGHT PLACE. Welcome to the
> BritishV8 forum!
>
> Unfortunately, your message was in the wrong
> sub-forum ("Other British Cars") so I've moved it
> to our "Engine" section where hopefully you'll get
> more and better response.

ok, thanks for that...

hopefully someone here would have done this without going stand alone!!


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6468 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: R/R 4.6 V8 going s/density?
Posted by: BlownMGB-V8
Date: December 10, 2008 04:43PM

Wasn't the old Federal ECU a speed density system? Maybe that could be made to work. Also have you looked at MegaSquirt yet? Pretty cheap...

Jim


mark3
mark broad

(3 posts)

Registered:
12/09/2008 05:53PM

Main British Car:


Re: R/R 4.6 V8 going s/density?
Posted by: mark3
Date: December 12, 2008 09:44AM

would thing be made more confusing if multipoint lpg was thrown into the mix?


Moderator
Curtis Jacobson
Portland Oregon
(4576 posts)

Registered:
10/12/2007 02:16AM

Main British Car:
71 MGBGT, Buick 215

authors avatar
Re: R/R 4.6 V8 going s/density?
Posted by: Moderator
Date: December 12, 2008 10:47AM

Jim wrote: "Wasn't the old Federal ECU a speed density system?"

That system used a flapper type mechanical air-flow sensor... "L-Jetronic".

I think the term "speed-density" applies to any system where the main sensor is a pressure sensor. The Bosch system that preceded L-Jetronic in the late sixties (D-Jetronic) was a speed-density system. It had an early MAP sensor... but much more modern systems like MegaSquirt are speed-density systems too.

ref: [en.wikipedia.org]
Quote:
An engine control system that uses manifold absolute pressure to calculate air mass uses the speed-density method. Engine speed (RPM) and air temperature are also necessary to complete the speed-density calculation. Not all fuel-injected engines use a MAP sensor to infer mass air flow; some use a MAF (mass air flow) sensor. Several makes use the MAP sensor in OBD II applications to test the EGR valve for functionality. Most notably General Motors uses this approach.

We've had a couple BritishV8 articles that discuss or focus on speed-density systems. For example, Kelly Stevenson wrote about them in the context of Ford 5.0 EFI options:

[www.britishv8.org]
Quote:
The two basic sensor technologies to choose between are "speed density" and "mass air". The speed density system came first (generally around model years '85-'88), and it's adequate. Speed density systems rely heavily on manifold air pressure (MAP) sensors as a further input to the ECM in order to estimate engine load. Mass air systems (from about model years '89-'93) use a hot-wire sensor to actually measure the air flow entering the throttle body. (Passing air cools the element, which changes its electrical resistance.) Instead of a MAP sensor, they use a barometric air pressure (BAP) sensor. They also use two oxygen sensors, an air charge temperature (ACT) sensor, an engine coolant temperature (ECT) sensor, and a throttle position (TPS) sensor. Don't let all these sensors intimidate you! Their electrical connections are all different so they can't be crossed up. The two important things you will want to note are: (1) that none of the electronic parts of speed density systems are interchangable with the later mass air system parts, and (2) the mass air systems are much more "tune-able". In fact, the mass air systems are preferred because they're actually self tuning: their ECM has the ability to modify or "learn" changes as they occur and to adapt to them. (For example, the mass-air ECM can adapt better to changes in altitude or fuel quality.)

Mark, you'll want to check out the EFI part of this amazing and inspirational article:
[www.britishv8.org]

We've had a couple articles that mention aspects of MegaSquirt... but I'm still looking for a volunteer to describe the installation and tuning of MegaSquirt from beginning to end.


V8Tech
Shaun O'Donnell

(19 posts)

Registered:
01/12/2009 11:37AM

Main British Car:


Re: R/R 4.6 V8 going s/density?
Posted by: V8Tech
Date: January 12, 2009 12:22PM

Mark wrote "would thing be made more confusing if multipoint lpg was thrown into the mix?"

IMHO .. the lpg conversion is likely to spring liner leaks!! I have been working on these engines for 12 years and 90% of liner failures seem to happen on lpg converted vehicles!!! The cylinder burn temperature is certainly a good deal hotter than that of gasolene and this may be the cause .. but buyer beware!!!

The air mass meter in the RR 4.6 is acheivable but the benefits are only really going to be seen by using an aftermarket system to run the fuelling and ignition .. the standard GEMS system relies too heavily on the Lambda sensor readings and air mass to control the fuelling and the results are exactly as you describe 'a little flat'. The 4.6 with something like megasquirt, OMEX or Emerald, will definitely produce the power you want but you may encounter some problems with the original GEMS system control over the rest of the vehicle .. I would recommend contacting Mark Adams (Tornado chips) in the UK before making a decision .. he will be able to tell you the effects of the ECU bypass.
Shaun



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