Hello,Just wanting to know if anyones running 1'' 3/4 SU's ? And what you think of them are they to big? or not..I have a fairly worked head and am trying to get a idea as to what they are like..Also would like to know what jet size ,needles and springs you use, You can P.M me if you like..Cheers

Hi,

I have twin 1 1/2' on my Cooper S which has been dynoed at around 65 - 70hp at the wheels. 1275 +40, Kent Megadyne 286, 12G940 Head modified with Mk1 valves. Longman extractors with RC40.
I guess it depends on the size of the motor but I think 1 3/4" may be too big.

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1969 Cooper "S"
1967 Mini Deluxe
1973 Clubman Van (the fleet spare)
1978 ex 1275 LS ("Wizard" Eaton Supercharged)
2015 HSV GenF GTS(occasional drive & tow car)
2019 MINI F55 Cooper S

There's a guy over here in the west that's running them...Just got to somehow get in contact with him!! I think the overkill would highly depend on jet size and needle selection..I to am running twin 1''1/2''s ...But am on one of the richest needles for 90'' jets,may step up to 100'' jets...Just seeing if anyone has been there done that to see how things went...anyone?? Thanks

Check your PM's

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Message recieved...Cheers!! Still interested in hearing from anyone who is ,or has run this type of setup...Thanks.

I'm keen to see more discussion on this cause there's a WHOLE lot of crap on the topic.

Here's what I'm on about: If you read anything on "why is a 1 3/4 (or equivalent) just as good or better than twin 1 1/4's then you'll see a bunch of stuff on how siamese port heads and twins work, and how each port only ever sees one carb etc so 1 3/4 is better etc etc

But hold on, if each port only sees one carb, then how can twin 11/4 be any where NEAR enough.....and how come 1 3/4 can be too much???

It can't go both ways....so I just wish I could get some sense on the topic.....

Hopefully the person I told suffolk about will give some more details but he was running twin 1 3/4's on his mini last I'd heard . So long as the motor is "big enough" to get the air flow through them you should be fine . I've seen a full race 998 with twin 1 3/4's but everything only worked on it at high revs .

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Exactly!! The book ive got says
2x1''1/4 850cc t0 1500cc 50 t0 100 Bhp
2x1''1/2 1000cc to 1800cc aprox 60 to 110 Bhp
2x1''3/4 1500cc to 3000cc 105 to 170 Bhp
Not forgetting that they slow down or fade of at the higher end of the BHP figures above..Cheers

Yes there still on there last time I looked

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here are my 1 3/4's.

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*Reasonable pricing
*I come to you..
Jay: 0431404607

very neat clubmn!

love the engine colour to!

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Here am I sitting in my tin can far above the Moon
Planet Earth is blue and there's nothing I can do...



“A turbo: exhaust gasses go into the turbocharger and spin it, witchcraft happens and you go faster.” - Jeremy Clarkson

I LOVE them,,, they`re my favourite

well,,, maybe except for my twin 2" set up

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

4 what application

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*Reasonable pricing
*I come to you..
Jay: 0431404607

My little roady 1510cc donk

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

Thanks for all the reply's...Ive heard nothing but positive feedback on 1'' 3/4 SU's...I'm getting a set to try out in the future...It will be just a matter of getting the right spring and needle combo...and ''Bobs your Aunty''..Cheers