Mini 3 Port Injection

mikos · Post by **mikos** » Tue Apr 12, 2005 1:00 pm

hi, very new to this so go easy

i have an MS on my turbocharged mini, was wondering how to go about going to full EFI on the mini's 5 port head, seeing as we only have 2 inlet ports.

Bill Shurvinton · Post by **Bill Shurvinton** » Tue Apr 12, 2005 1:26 pm

If it were me then I would get a single TB with 2 injector ports. Ducati
one should do. 50mm so a little big, but a pair should only set you back
£50 and you can sell the other one.

2 400-500cc injectors. Run 4 squirts alternating. Should work like a
dream as the injectors can overlap, giving the same effect as a single
1000cc injector, but with better low end control.

Easy peasy.

Bill

mikos wrote:

> hi, very new to this so go easy Smile
>
> i have an MS on my turbocharged mini, was wondering how to go about
> going to full EFI on the mini's 5 port head, seeing as we only have 2
> inlet ports.
>
>
>
> Click here to go to forum page: http://www.msefi.com . If you want to
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racingmini_mtl · Post by **racingmini_mtl** » Tue Apr 12, 2005 2:13 pm

I agree with Bill for the setup and configuration.

As for the TB, you could look at the Honda RC51 which also has two 2-injector TBs and might be easier to find and cheaper.

Jean

mikos · Post by **mikos** » Tue Apr 12, 2005 2:23 pm

so were talking two carbs rather than say a single Jenvey with 2 injectors?

racingmini_mtl · Post by **racingmini_mtl** » Tue Apr 12, 2005 2:33 pm

No. Actually what Bill and I are saying is to use only one of the 2 TBs from a motorcycle. This will be similar to the 2-injector Jenvey but will very likely be much cheaper.

Jean

mikos · Post by **mikos** » Tue Apr 12, 2005 2:46 pm

ah gotcha.

Bill Shurvinton · Post by **Bill Shurvinton** » Tue Apr 12, 2005 2:46 pm

No single body, 2 injectors. Jenvey would work great.

mikos wrote:

> so were talking two carbs rather than say a single Jenvey with 2
> injectors?
>
>
>
>

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lapuwali · Post by **lapuwali** » Tue Apr 12, 2005 2:47 pm

What's not being said explicitly but only implied is that you should abandon any hope of "port" injection in your A-series unless you want to do a LOT of development. Throttle body injection works fine. One larger TB will be easier to set up than two smaller ones, as well as cheaper.

mikos · Post by **mikos** » Tue Apr 12, 2005 2:57 pm

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.

cng1 · Post by **cng1** » Tue Apr 12, 2005 3:07 pm

"lapuwali" wrote:
> What's not being said explicitly but only implied is that you should abandon any hope of "port" injection in your A-series unless you want to do a LOT of development.

Well we'll soon see as I'm doing just that, sure half of the cylinders
will have to run a bit richer than the others but if you're prepared for
that there really shouldn't be a problem. Yes siamese ports are a pain
but only if you're going for ultimate economy or emissions compliance.

(posted by email)

Bill Shurvinton · Post by **Bill Shurvinton** » Tue Apr 12, 2005 3:10 pm

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
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cng1 · Post by **cng1** » Wed Apr 20, 2005 11:48 am

"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)

lapuwali · Post by **lapuwali** » Wed Apr 20, 2005 2:15 pm

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

cng1 · Post by **cng1** » Wed Apr 20, 2005 2:25 pm

"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)

Bill Shurvinton · Post by **Bill Shurvinton** » Wed Apr 20, 2005 2:52 pm

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.

cng1 · Post by **cng1** » Wed Apr 20, 2005 3:19 pm

"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)

cng1 · Post by **cng1** » Thu Apr 21, 2005 7:03 am

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)

mikesb · Post by **mikesb** » Sun Apr 24, 2005 7:32 pm

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?

mikesb · Post by **mikesb** » Mon Apr 25, 2005 6:54 am

So tired last night, I forgot to say "Just got my B series running on MS this afternoon - woohoo

!!!!"