You don't. You live with it.
OR you get an 8 port head.
mikos wrote:
> also i'm running a cam with some overlap, so on each revolution i'm
> gonna have neighboring cylinders with each inlet open so how do i get
> around charge stealing.
>
>
>
> Click here to go to forum page: http://www.msefi.com . If you want to
> stop all emails from msefi.com, send us a note at megasquirt@shaw.ca
> <mailto:megasquirt@shaw.ca>
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(posted by email)
Mini 3 Port Injection
Forum rules
Read the manual to see if your question is answered there before posting. If you have questions about MS1/Extra or MS2/Extra or other non-B&G code configuration or tuning, please post them at http://www.msextra.com The full forum rules are here: Forum Rules, be sure to read them all regularly.
Read the manual to see if your question is answered there before posting. If you have questions about MS1/Extra or MS2/Extra or other non-B&G code configuration or tuning, please post them at http://www.msextra.com The full forum rules are here: Forum Rules, be sure to read them all regularly.
-
Bill Shurvinton
- MegaSquirt Newbie
- Posts: 23
- Joined: Fri May 07, 2004 1:20 pm
- Location: My Hampshire Hill
-
Secret Chimp
- MegaSquirt Newbie
- Posts: 1
- Joined: Tue Apr 19, 2005 6:14 pm
- Location: Orange County, CA
I have been thinking about this a lot lately also. I have a turbo motor on the floor in my garage. And I'd like to dump the carb in favor of fuel injection to power my set-up w/GT15 turbo.
But instead of going through the trouble of getting motorcycle throttle bodies, why not just use the throttle body used in the Multi-point injection (MPI) motors as used in minis produced in the late 1990's? It uses two injectors, and is already set up to mate with the 2 intake ports on the 1275 motor.
SC~
But instead of going through the trouble of getting motorcycle throttle bodies, why not just use the throttle body used in the Multi-point injection (MPI) motors as used in minis produced in the late 1990's? It uses two injectors, and is already set up to mate with the 2 intake ports on the 1275 motor.
SC~
Mini 3 Port Injection
"Secret Chimp" wrote:
> But instead of going through the trouble of getting motorcycle throttle bodies, why not just use the throttle body used in the Multi-point injection (MPI)? It uses two injectors, and is already set up to mate with the 2 intake ports on the 1275 motor.
I'm just doing exactly that. I haven't yet mapped it yet but it starts up
on the megasquirt. In theory as long as you're prepared to run two cylinders
a bit rich then there should be no problem.
(posted by email)
> But instead of going through the trouble of getting motorcycle throttle bodies, why not just use the throttle body used in the Multi-point injection (MPI)? It uses two injectors, and is already set up to mate with the 2 intake ports on the 1275 motor.
I'm just doing exactly that. I haven't yet mapped it yet but it starts up
on the megasquirt. In theory as long as you're prepared to run two cylinders
a bit rich then there should be no problem.
(posted by email)
The charge stealing issue is actually quite serious. You're not the first to travel down this path. It is obviously possible, as the MPi engine shows, but it requires some tricks that MS will have a hard time with.
Running rich doesn't fix the problem. You end up with one very rich cylinder and the other very lean, in each pair. The TIMING of the injections relative to the valve events is very critical, and is how the MPi system works. You basically must run full sequential even under full loads, and you must use very large injectors so they flow enough in a narrow time window at full load, and run them right down to an absolute minimum pulsewidth to get a good idle. Or, you have to run staged injectors, but still run everything full sequential. The MS doesn't do sequential at all, and doing it over the full range of engine loads is very tricky.
Many people have stated that MPi has an upper power limit, even with the one ECU that's tunable, simply because if you put in larger injectors to support more power, you now can't open and close them fast enough to get it to idle. Again, staged injectors would fix this, but no one has yet developed it.
Some details can be found here, from someone else who's been there, and gave up:
http://www.planet.eon.net/~chichm/efi/efi.htm
Running rich doesn't fix the problem. You end up with one very rich cylinder and the other very lean, in each pair. The TIMING of the injections relative to the valve events is very critical, and is how the MPi system works. You basically must run full sequential even under full loads, and you must use very large injectors so they flow enough in a narrow time window at full load, and run them right down to an absolute minimum pulsewidth to get a good idle. Or, you have to run staged injectors, but still run everything full sequential. The MS doesn't do sequential at all, and doing it over the full range of engine loads is very tricky.
Many people have stated that MPi has an upper power limit, even with the one ECU that's tunable, simply because if you put in larger injectors to support more power, you now can't open and close them fast enough to get it to idle. Again, staged injectors would fix this, but no one has yet developed it.
Some details can be found here, from someone else who's been there, and gave up:
http://www.planet.eon.net/~chichm/efi/efi.htm
'71 Porsche 914 2.2
'69 VW Squareback
'69 FIAT 124 Sport Coupe
'69 VW Squareback
'69 FIAT 124 Sport Coupe
Mini 3 Port Injection
"lapuwali" wrote:
> Running rich doesn't fix the problem. You end up with one very rich cylinder and the other very lean, in each pair.
You run 4 squirts per cycle and that helps to even things out. Sure it's not
as good as a wet manifold but it's plenty good enough - as I hope to prove
within the next couple of weeks.
>The TIMING of the injections relative to the valve events is very critical, and is how the MPi system works.
It's critical to getting the emissions to the standards required of an OEM
and required to keep a catalyst happy. For people like us it's really
not an issue.
(posted by email)
> Running rich doesn't fix the problem. You end up with one very rich cylinder and the other very lean, in each pair.
You run 4 squirts per cycle and that helps to even things out. Sure it's not
as good as a wet manifold but it's plenty good enough - as I hope to prove
within the next couple of weeks.
>The TIMING of the injections relative to the valve events is very critical, and is how the MPi system works.
It's critical to getting the emissions to the standards required of an OEM
and required to keep a catalyst happy. For people like us it's really
not an issue.
(posted by email)
-
Bill Shurvinton
- MegaSquirt Newbie
- Posts: 23
- Joined: Fri May 07, 2004 1:20 pm
- Location: My Hampshire Hill
Mini 3 Port Injection
"Bill Shurvinton" wrote:
> Not that b*******D link again.
> Chris has 2 widebands, and I can always find him more, so lets not quote doomsaying websites and let someone actually MS an A-series, instrument it and then we will see how 'serious' it is.
Give me a couple of weeks and I'll report back, been a bit distracted of
late trying to see if I can break the 3HP/ci barrier with a $1000 engine
with completely stock internals.
FWIW with regard to the a-series my money is on charge robbing not being
as a major issue at all, my expectation is that the cylinders see are differ
by 1 point on the afr ie 13:1 vs 14:1. Even if it's more like 2 points
that's still perfectly acceptable to me. One thing that I do note
is that the rover TB doesn't actually open all the way and the butterfly is
tapered. My hypothesis is that they've done this to introduce a vortex as
the air swirls through the "plenum" into the runners aiding the mixing.
(posted by email)
> Not that b*******D link again.
> Chris has 2 widebands, and I can always find him more, so lets not quote doomsaying websites and let someone actually MS an A-series, instrument it and then we will see how 'serious' it is.
Give me a couple of weeks and I'll report back, been a bit distracted of
late trying to see if I can break the 3HP/ci barrier with a $1000 engine
with completely stock internals.
FWIW with regard to the a-series my money is on charge robbing not being
as a major issue at all, my expectation is that the cylinders see are differ
by 1 point on the afr ie 13:1 vs 14:1. Even if it's more like 2 points
that's still perfectly acceptable to me. One thing that I do note
is that the rover TB doesn't actually open all the way and the butterfly is
tapered. My hypothesis is that they've done this to introduce a vortex as
the air swirls through the "plenum" into the runners aiding the mixing.
(posted by email)
Mini 3 Port Injection
Chris Good wrote:
> You run 4 squirts per cycle and that helps to even things out. Sure it's not
> as good as a wet manifold but it's plenty good enough - as I hope to prove
> within the next couple of weeks.
Just spent the morning talking to a chap running an injected midget. He's
currently running multiple squirts per cycle and it works just fine - he's
got twin lambda bosses in his exhaust and his car lives at a rolling road
place so the info should be accurate. What he did say is that on the
A-series once you start running hairy cams to get 115bhp+ it starts getting
tricky to get big enough injectors that will still idle OK. He
suggested that the solution was to either run 2 banks of injectors but that
he would like to try changing the number of squirts per cycle as the revs
increase.
(posted by email)
> You run 4 squirts per cycle and that helps to even things out. Sure it's not
> as good as a wet manifold but it's plenty good enough - as I hope to prove
> within the next couple of weeks.
Just spent the morning talking to a chap running an injected midget. He's
currently running multiple squirts per cycle and it works just fine - he's
got twin lambda bosses in his exhaust and his car lives at a rolling road
place so the info should be accurate. What he did say is that on the
A-series once you start running hairy cams to get 115bhp+ it starts getting
tricky to get big enough injectors that will still idle OK. He
suggested that the solution was to either run 2 banks of injectors but that
he would like to try changing the number of squirts per cycle as the revs
increase.
(posted by email)
Just got my B series running on MS this afternoon, it's a siamese port engine as well.
It's wet manifold (two) using two RC51 honda cycle throttle bodies much like the original. The RC51 TBs have 2 injectors per TB with a perfect total flow rate for the 'B.
So far it idles nice and revs with no load just fine. The M/C throttle bodie set up is no different than the SU's I replaced, so I don't expect any charge robbing problems worse than with the stock carbs (none).
I shouldn't need much in the way of instrumentation, plug cuts work fine with this engine & available fuel. I'll be able to see a difference between the inner and outer plugs if there's a problem.
I've still got a few things to sort out before I can try it on the street. When I do, what kind of things would you all like me to check with it?
It's wet manifold (two) using two RC51 honda cycle throttle bodies much like the original. The RC51 TBs have 2 injectors per TB with a perfect total flow rate for the 'B.
So far it idles nice and revs with no load just fine. The M/C throttle bodie set up is no different than the SU's I replaced, so I don't expect any charge robbing problems worse than with the stock carbs (none).
I shouldn't need much in the way of instrumentation, plug cuts work fine with this engine & available fuel. I'll be able to see a difference between the inner and outer plugs if there's a problem.
I've still got a few things to sort out before I can try it on the street. When I do, what kind of things would you all like me to check with it?
