SU DU Carbs

[JohnA]

This was on the SU Stand at Goodwood Revival a mock up using a 3D Printer. It was mounted on swiftune engine.
The Original DU carb was a racing carb and not fitted with a choke mechanism.
The man said the new carb gave better power than a 45DCOE.

[Oldskoolbaby]

Would look pretty nice on the front of an 8 port.

[surfblue63]

Tim Harber tried one of these on his racer a few years ago.

[mk1]

What was it like Tim?

M

[33JOY]

Or, for those that prefer a split Weber set up, you could use two single SUs....

Peter

[Tim Harber]

What was it like Tim?

M

On the rollers it gave the same power as a Weber , so I took a chance and we fitted it for a race at Donington. In it's one and only use in action, it fluffed mid range and it peed out fuel from one of the outlets/inlets that we hadn't blocked off. In truth , we fitted it on a whim with no forethought, so we took it off for the race.

It was designed to work as one of a pair or three and had several intricacies that probably need to be thought through to run in its own right. It gave more power than a pair of HS6's with the same needles but they were on a short manifold and by nature (HS6 = Horizontal Short) the carb sat much closer to the motor which probably was'nt helping

The Weber gives 9 bhp more than the H4's but in practical terms , the SU's seem to be a better bet and I have left them on for the last two seasons. I can keep up in a straight line with Roger Godfrey who has a Weber on a long inlet and a Swifty motor. It's the cornery bits that I struggle with on occasion

[Oldskoolbaby]

Am I right in saying that the centre to center measurement of the barrels is quite abit smaller than tthat of a dcoe? Also, as far as tuning one at the rolling road, how available are the needles etc? Do they use similar parts to more common SU carbs?

[steve65]

A few pics.

[steve65]

A few pics.

From memory I think they use ordinary SU needles.

[Sean1380]

Looks gorgeous

[ivor badger 2]

Looks gorgeous

But does it work? The carb was built for a job and that job was not a mini. What is the point of fitting a carb when the only way to fit it is to use a poor inlet manifold. you can fit the equivalent on a decet twin manifold and make it work.

Btw HS means sloped SU and H means horizontal.

[Jamie]

Would like to hear the noise that makes!

[ivor badger 2]

Would like to hear the noise that makes!

Is that any different from twin HS6s or a 45 Weber and probably inaudible above the straight cut gears.

[steve65]

It sounded good, quite different to anything else, and gave good power on the rollers even with the short manifold. A 45 weber also wasnt "made for a Mini" but works well all the same!

[Sean1380]

Looks gorgeous

But does it work? The carb was built for a job and that job was not a mini. What is the point of fitting a carb when the only way to fit it is to use a poor inlet manifold.

I 100% agree there.

I run a HIF44 on my 1380, but, if cost were not a factor (our silly African money is now 21 to one GB Pound) for looks i would have a pair of HS4's over the HIF44, and only because they look good

[su_mark]

You might be interested in this...?!

https://youtu.be/BdNnn8_CwkI

[ivor badger 2]

You might be interested in this...?!

https://youtu.be/BdNnn8_CwkI

Sounds like any other mini in similar circumstances. How much does the proximity of the ram pipes to the bulkhead restrict the performance?

[su_mark]

It's all a bit bodged up at the moment to be fair, just to fit it under a standard bonnet/bulkhead. It runs well, although the obvious restrictions (manifold,bulkhead,rampipes) don't do it any favours.
Figures up to 5500rpm are far better than H4s but got to sort out the top end before releasing proper data.
At this point it's more for my own fascination than anything else. A kind of 'can it be done?' thing.
There will be an 1 1/2" version too which may be more suitable for most Mini applications...

[ivor badger 2]

It's all a bit bodged up at the moment to be fair, just to fit it under a standard bonnet/bulkhead. It runs well, although the obvious restrictions (manifold,bulkhead,rampipes) don't do it any favours.
Figures up to 5500rpm are far better than H4s but got to sort out the top end before releasing proper data.
At this point it's more for my own fascination than anything else. A kind of 'can it be done?' thing.
There will be an 1 1/2" version too which may be more suitable for most Mini applications...

If you are running up to 5500 rpm, I cannot see any advantage or even any reason for increased performance except at the very top end of your rev range. Twin HS2s would provide enough air to reach 5500rpm, an 850 or 1000 could reach that on a single. An S could reach 7000 on twin HS2s. Twin HS6s or 45 DCOE with the correct chokes, ie 40s are for going to 7500 + with the rest of the bits to get it there. Fitting these carbs for any other reason is simply cosmetic and trying to impress people with the car stationary.

[su_mark]

Perhaps I didn't make that clear enough. This is my mk1 racer and happily revs to 8000. With the DU carb it is leaning off after 5500 (not unexpectedly) and that is where I need to spend my time next...
I'm reasonably well versed in SU fitment/sizing etc. As I said, this is really for a bit of fun at the moment... Just thought peeps might be interested...