21 replies to this topic

[maxmaniac]

Hi all!

I'm not sure if I should post here or on the technical section, but...

Since I'm the owner of a standard 1970 Austin Mini 1000 (998), and its hs2 is somewhat tired, I was thinking of going for a twin hs2 setup as the 998 Coopers.

Since the standard inlet/exhaust manifold combo will become useless, I'll also need a new exaust manifold and, while I'm at it, also change the complete exhaust.

I was thinking of two different approaches:

- Maniflow cooper freeflow + Maniflow 1,75" twinbox

- Sportex LCB + Sportex Rally twin silencer 2"

 

My main goal isn't really performance, but to give a bit of life to the beast 

From what I can tell from exploring this forum, Maniflow quality is top notch and Sportex tend to rust a bit quicker (but that black exhaust looks awesome!).

 

I would like to know what are your thoughts regarding these two systems and what do you think about twin hs2 on an unmodified 1000.

Also, what are the main differences between the standard 1000 and the 998 Cooper apart from the carburettor setup and the disk brakes.

 

Thank you all!
 

[Bubblebobble]

The cylinder head is a much better item , but i gather you either need higher compression pistons or the head needs burretting [ measuring ] to see what the cc of it is , then skimming down .

[KernowCooper]

Different Head as said above, different camshaft carbs, exhaust, a standard Cooper 998 makes 55bhp a standard 998 mini 38bhp 'ish. Your head will be your biggest restriction on performance, and dont go big on the exhaust as it will loose any benefit your adding and some, even 1 3/4 is to big for a 998 really

[jaydee]

Use Maniflow/RC40 forget about the sportex stuff

[maxmaniac]

Thanks for your replies!

 

It would be too easy just to change carbs and exhaust...

So, probably I'll leave it with just one carb as is before blowing something up!! 

But the exhaust... I hate the original one... Sounds a bit dead to me. 

[blacktulip]

Your about to tumble into the full on quest for more power. Head, cam, stage 1 kit and a rolling road session.

[maxmaniac]

Well, I don't know if I can afford all that, but it wouldn't suprise me   
Normally I don't really bother to have some lack of power; although my mini isn't really quick, it can easilly do 130 kph (~80 mph)...
Are these normal figures for a standard 1000?

My main priority is to maintain this little guy alive for as long as I can... He knows me since I was a baby!

[timmy850]

The 998 cooper:

Head was a 12G295, with big combustion chambers

Pistons were "D" top with raised tops to increase the compression ratio

Nicer cam

Twin HS2 carbs

Extractor style exhaust manifold

7" disc brakes

 

You could swap to a new exhaust and a pair of HS2 carbs on your current engine, you just won't get as much power as a 998 Cooper..

 

A good, rebuilt set of HS2's aren't going to be that cheap either (once they are cleaned up, new spindles, bushes, filters, linkages, manifold, etc), you might be better off with a Stage One kit and an HS4 single carb?

[Ethel]

Twin carbs are a lot of money for little or no return on an otherwise standard car. Start with the exhaust and better inlet & exhaust manifolds.

[maxmaniac]

Thats a good alternative, yes.
The only reason I wrote about the twin hs2's was because I thought the difference between engines was not that great (naive me!).

But now I'm rather reluctant... Would the twin carbs caus too much strain on standard 1000 components?

 

But I won't deny that it's rather cool to have a twin setup (and a pain to set it up also, I believe) 

Edited by maxmaniac, 24 September 2014 - 12:55 AM.

[maxmaniac]

Twin carbs are a lot of money for little or no return on an otherwise standard car. Start with the exhaust and better inlet & exhaust manifolds.

 

I was convinced that by using dual carbs, the increase would be noticeable.

But well, the purpose of these kind of discussions is to learn from who knows best!

 

Thank you all!

[timmy850]

You won't get a big increase from your engine by swapping to dual carbs if the single carb has been feeding your engine fine. It's an interconnected system.

 

E.g: (completely random numbers, not facts by any means!)

 

HS2 Carb flows 110 cubic feet per minute

Inlet manifold flows 100 cfm

Head flows 120 cfm

Exhaust manifold flows 100 cfm

 

In this case you'd be better off doing working on/swapping your carb, inlet and exhaust to get them to match your head. If you wanted more performance after that, you'd need to get a better flowing head. If you can get a copy of the David Vizard book, it's a great place to look and plan around what you can do to get more power.

 

 

For my car, I'm building a 998 Cooper style engine. I bought a set of Cooper S carbs for $120. Then the manifold was $50, rebuild kit was $150, air filter case $170. I still need to get the linkage kit, heat shield kit, fuel pipes, air filters, etc before I can use them... Alternatively I have a $50 HS4 that's been rebuilt sitting here that would do much the same job!

[Ethel]

A carb can only ever supply as much fuel/air as is demanded by the engine. I'd think to a  large degree the Cooper had twins as it's what the market expected on a performance model, though you do get a slightly shorter and straighter inlet tract that can help throttle response a bit.

[maxmaniac]

I see...
All your explanations make perfect sense. Thanks!
But then again, a Stage 1 kit for a 998 with inlet and exhaust manifolds, air-filter and carburettor needle would make me think that there is still something to extract from this head.

 

There's always a nice way to find out, eh? 

[maxmaniac]

Just a brief update... It seems that the standard 998 wasn't exactly that standard: the head is a 12g202.

It seems that during the 90's the original head just fell apart and someone put this one instead.

From what I've read, this head is slightly better than the original one, but I have no way of telling if it has been skimmed or not without measuring. I would thinks so, otherwise performance wouldn't be that great, right?

 

If any of you have any experience in this kind of 'hybrid', I would be pleased to read about it!

Edited by maxmaniac, 02 October 2014 - 03:55 PM.