Exhaust Manifold Choice

[Kevin]

In the near future ( when I finally make up my mind and stop procrastinating ) I will be replacing my 1098cc with a 1275cc Midget engine and my question is what to do with the exhaust manifold, I have an 1 3/4" carb & inlet manifold but which direction do I go for the exhaust ?
Should I go with a Mini so that I can keep the standard exhaust (and the note) or will it strangle the engine.
Or should I use a Marina or Ital one (are their other BMC ones) as the engine will be fairly standard I dont think the type that Cam has gone for (full flow) will be of benefit, but I am open to all suggestions and happy to be proved wrong, what have others got/done.
I do not want to use a K & N air filter unit as personally I think they have too much induction roar.

[Innovator]

I would guess that you are fitting the 1275cc engine because you want more power. It would be a shame not to utilise the engine to the maximum. Therefore a LCB (long centre branch) manifold is your best bet matched up to a free flowing exhaust system (RC 40 is very good).

The single 1 3/4 SU is ideal especially if it is a later type with the float chamber underneath.

In my opinon (because David Vizard says so, and he knows a lot) the K&N filter is the best you can get. The noise issue is not due to the filter element but the housing it is in. If you put a K&N element in a filter box or housing them it is possible to make it very quiet.

One final comment. Once you have got everything done get the carb set up on a rolling road by an operator who knows what he is doing. If you are not prepared to do this then my advice would be to stick with the 1098cc engine. The rolling road tune up is that IMPORTANT. It will be the best money you will spend and the source of the greatest power increase plus better running and fuel economy. I hope that convinces you!

John

www.beardmorebros.co.uk

[Cam]

Well said, John.

My exhaust system will allow your engine to breathe more easily and having a K&N filter in a standard filter housing will do the trick nicely without creating induction roar (which I like personally ).

You COULD use a mini exhaust but not as standard and you will have to do some cutting and bending to get the thing to fit (especially in the manifold area), but they are excellent exhausts, I still have 2 from my mini days!

The easiest (and possibly the best) option is keep what you have, get an exhaust system like mine and a metro/maestro filter box with a K&N filter.

[Kevin]

Thanks John & Cam
I seem to have misled slightly I meant by the mini manifold just to use it with a minor system if practical but from your replys its as I thought it will restrict things too much.
As for the K&N I meant that I did not want one of the open types I did realise that you could get the filters for some of the standard canisters but did not know what type (I do now)
John is there anywhere or a make you could reccomend fot the manifold as Cam has had a few problems with his Falcon one, also where does an RC40 system come from.
And yes when I get to that stage a rolling road was on the list, can they still be used if you are running in an engine or only once its run in (I am assuming the engine I am getting needs a total rebuild)

[Innovator]

Kevin,

I am unsure where to get manifolds from, its been a long time since I had an A Series in a Minor. Janspeed used to make a very good manifold, and should still be available, probably will not be cheap though.

The RC 40 is a system (or silencers) made for the Mini, again I am unsure if anybody makes them for a Minor, so it may be a case of adapt a Mini system for a Minor.

The ideal situation regarding rebuilt engines and rolling roads especially if the mixture is unknown is a basic tune up at low revs as soon possible after starting the new engine. Then once it is run in a full power tune up.

If you are going to do any tuning then buy Vizards Tuning the A Series book. It is another source of cheap power!

John

[Gareth]

...another source of cheap power!

So if I put that on the parcel shelf, (next to my travel rug and Panama ) will I get an extra bit of "go"?

[Cam]

will I get an extra bit of "go"?

Only if it is open, if it's closed you won't get anything. Silly boy!

[Peetee]

I am unsure where to get manifolds from

Maniflow in Salisbury offer a couple of systems for the minor, the difference being in the bore size. This parallels Dave Vizards advice so I would conclude that they are a better choice than an 'oversized' system that may give you the edge in the top revs but wrecks your mid range torque.

[Kevin]

Thanks for that guys this is going to take a bit of chasing around to see whats available
Gareth I thought your Panama lived in your boudoir ( fully carpeted pampering area, boot to those that dont know Phyllis )
I thought you parcel shelf was full of John Denver tapes, but what do I know

[Cam]

Ha ha, yes that's a good description of Gareth & Phyllis (snigger )

Actually, for your 1275 Midget engine in standard tune, the Falcon system might be about the right size (bore). It's a little bit big for the standard 1098 but too restrictive for my tuned high compression 1380. I have spoken to other people at the rallies who have the same system as me and they have had no problems with it. Including a chap with a 1430 in a similar state of tune to mine.

I think maybe I was unlucky and they HAVE improved their quality control now (thanks to me and my misfortune) so this might be the way to go.

The maniflow system is a larger bore than the Falcon one and so might not be the ideal choice for your 1275. Plus you have got the hassle of making a custom system up for it.

[Gareth]

Ah! Foiled again!
[Wanders off whistling 'Rhymes and Reasons']

[MikeTrav68]

RC40 is a system designed and owned by Mini Spares in London, with a US based web site under 'Mini Mania'. I can vouch they are excellent on Minis up to about 120hp, straight thought, A-series tone yet quiet. You can't really avoid an A-series sound, which comes from the siamesed exhaust port. Best noise deadening from the two box since the length between them is tuned - don't know how that packages on a minor since it's welded. Maybe they do a minor version now. The f'glass eventually looses its sound absorbtion so I've gone for the mild steel and replaced (5 years).

[MikeTrav68]

I should mention, on dyno tuning, you can do a reasonable job on the road (with much more time and a selection of needles!) using a Bosch Lambda sensor poked up the exhaust.

[Cam]

I have a few Vizard designed RC40s (twin and single box) in my garage from the Mini days, and they are VERY good systems. Unfortunately only the silencers could be used on the Moggy and the rest would have to be made up specially to fit.

You can set your car up without using a rolling road by the method you suggested but it's a lot of hassle and messing about and it will probably still be a fair bit off the mark, so I think a rolling road session is well worth it if you want the most out of your motor.

I have been promising to get mine rolling road tuned for 2 years now! It is still running on my guesswork!

With regard to the Lambda sensor, do you have the correct resistance values for the mixure settings?

[Peetee]

One option that has been missed is the twin downpipe as fitted to 1300 Metros. That should be cheaply sourced from a scrappy.
One supplier, Birmingham MMC I think, does a downpipe to fit to this. I have read that it's worth about +5 bhp on the 1300 over a standard cast single.

[Kevin]

Does that one still go off in the right direction ? because the mini LCB one does not, unless you use the short standard one.

[rayofleamington]

Hi Kevin,
How much power are you after?
My first Minor was a 1098 but with a 1275 head, an 1 3/4" carb and manifold and a larger bore exhaust (modified marina downpipe mated to a 2" straight through system). That was a big performance increase over the standard 1098.
At another time I ran a 1275 Midget engine but with the Minor 1098 manifold, carb and exhaust. That again was a major improvement in performance. (80mph up hills where only 60mph was possible with the 1098)

So if you took the 1275 engine with the 1 3/4" carb and manifold (Marina etc..) and a large bore exhaust I think you would have a very good combination. I have an inckling that the large bore exhaust for using a marina manifold is readily available off the shelf from 1 or 2 minor centres. That combination would probably be similar to the Marina set up, so might run well with standard jetting.
The standard marina exhaust would be more trouble than it is worth as it needs to be heavily modified around the engine bay, so the minor centre pre-made option would save time and effort.

I'm not saying there is anything wrong with going down the LCB exhaust manifold route, especially if you want to tune up the 1300, but just wanted to mention the alternative.

[Peetee]

Does that one still go off in the right direction ? because the mini LCB one does not, unless you use the short standard one.

Yes it does. It's only as long as the standard manifold. The twin downpipe mentioned is specifically for the Minor and mates to a larger bore exhaust system that is also stocked by the same supplier. They also do a downpipe/exhaust combo that fits to the marina manifold and is a cheeper option. I would think that unles you are going to hang on to the revs all the time you are unlikely to notice the extra bhp of a twin downpipe.

[Kevin]

How much power are you after?

Good question Ray
Right, since getting back into Moggies again a few years ago (maybe 7 or ) I have only had standard powered ones and a bit of hankering for something along the lines of a modified one with a bit more go, and I must confess it is not my daily driver apart from the summer months, so I do not want to go to far and when my big ends started to voice an opinion I thought now is as good a time as any and started to get some bits and pieces together.
So far that consists of a 1275 Midget engine (still to be picked up) full running condition as yet unknown, an oselli inlet manifold and a 1 3/4" carb.
I dont know if I want to lose the standard exhaust note or not hence my deliberations about an exhaust manifold.
I know that by using a Mini manifold I can use the standard exhaust, does this apply with the Metro one? So I may at first take this route and then change up at a later date if it is not succesfull although your remarks seem to point to quite a performance increase .
Also the brakes and suspension will have to be improved which as I am not looking at ultimate performace is why I will probably go down the bolt on suspension route (providing I can ever make my mind up)
And at the moment I am not looking towards a 5 speed box either.
Does this help with what I am trying to achieve, providing I dont confuse myself further or anyone else for that matter

[turbominor]

Grumpy's morris minor do a nice system that fits on to th ital manifold, or they do a minor syle lcb to suit. That should be easy to fit. may not give the maximum of the more expensive systems, but stuck me as a senible balence between £ and bhp

As long as you dont end up with a pipe that looks like an off cut from the iraqy super gun..................