Peter Cobbold Posted December 16, 2014 Report Share Posted December 16, 2014 Peter, wanting moer carb for your blower engine,!!! there is a 3" inch singl SU too. fitted to some Jags, cos a bloke brought a one off manifold, and .another 3" carb. M M, I didnt know that there's a 3inch single SU made for Jags. The Oz ones are specials: http://www.hi-flow.com/HP008aSU.html and 'only' 2.5inch ( I was mistaken about 3") Peter Quote Link to post Share on other sites
GTT Posted December 19, 2014 Report Share Posted December 19, 2014 The British had a tendency to go overboard on SU carb size. The Rover 2000TC never needed twin 2" cabs, nor did any of the racing MGs, which almost universally do far better on a pair of HS6 carbs. No they didn't. An SU carb must ALWAYS be oversized for the simple reason that the carb is a bucket of sh..t. Anyone who has ever delved into the vicissitudes of the SU or Stromberg carb design will tell you that in emission terms its the world's worst disaster. The British had the unique talent of producing a carburettor for 60+ years with the jet in precisely the WRONG place. Therefore a Su carb once it opens up more than about 1/2 way makes a horrible downstream mess of buckets of all sorts of droplet sizes, but most of them huge GOBS of fuel accompanied by gigantic wallops of stand-off. The reason why you would NEVER want to have a SU open up anything even close to 3/4 to fully open is because you will never get more power, you simply get loads of terrible emissions and what looks like over-richness, which is in fact a substitute for simple AWFUL fuel particle size. I can demonstrate this to you any day you like on a dyno, complete with a fog of stand-off. I know what happens next, is masses of insults in here for having committed the worst heresy, - slagging off a classic British POS. The dual SU probably can help a tiny bit, by increasing the choke sizes, but sure as eggs is eggs it doesn't get worse than what I described. Quote Link to post Share on other sites
RogerH Posted December 19, 2014 Report Share Posted December 19, 2014 Hi Gareth, you have a PM. Roger Quote Link to post Share on other sites
Peter Cobbold Posted December 19, 2014 Report Share Posted December 19, 2014 Stand-off from Webers: (about 1:15) Not only SUs. Quote Link to post Share on other sites
Motorsport Mickey Posted May 14, 2015 Report Share Posted May 14, 2015 Given that we are well into the early summer preparations now I wonder if the DU6 set up has been completed on Fins car and have we any feedback ? Mick Richards Quote Link to post Share on other sites
RogerH Posted May 14, 2015 Report Share Posted May 14, 2015 Hi Mick, didn't Fin sell his car just recently. Roger Quote Link to post Share on other sites
Motorsport Mickey Posted May 14, 2015 Report Share Posted May 14, 2015 Thanks Roger, didn't see that reported. Mick Richards Quote Link to post Share on other sites
RogerH Posted May 14, 2015 Report Share Posted May 14, 2015 Hi Mick, her was the thread http://www.tr-register.co.uk/forums/index.php?/topic/51470-tr4a-for-sale/?hl=sale Roger Quote Link to post Share on other sites
Keith Jenkins Posted November 10, 2015 Report Share Posted November 10, 2015 Hi Mick, On Fin's car there was no improvement with the DU6 carbs over his twin SU setup, no surprise really given that his car was standard. The real surprise was on Paul's car which gained an extra 8 bhp at the wheels with no losses in the mid range, in comparison with his Weber setup, so the SU DU6 setup was left on, after which Paul went on holiday in France I believe with the car and all went well. Not bad for an initial development on a tuned road car. Keith Quote Link to post Share on other sites
greggmay Posted November 10, 2015 Report Share Posted November 10, 2015 Hi Keith, good work with the DU6s on Paul's TR3. I drove it whilst in France earlier in the year and can confirm that it performs well with them installed, considerably better drivability than expected. The lack of 'accelerator pump' action when snap-opening the throttle at lower RPM was the only obvious consideration, when the engine was settled into constant acceleration it worked very well. With a little care initially opening the throttle it would pull very cleanly from 1500RPM onwards, being very responsive with some load and higher RPM on board. There are certainly plenty of average DCOE setups floating around on cars which do not work half as well as the DU6s on Paul's car. There is obviously more work that could be done to further improve the install but its an incredibly positive project so far. I'm interested to see the development of the installation and the manifolds etc. as I also have an original pair of DU6s that I bought from Viv 3 or 4 years ago. I hope to get my pair up and running on a car in the near-ish future. I know many people will ask why, and there are plenty of reasons why you wouldn't bother, but there are numerous compromises with whichever route you go. I just fancy giving the DU6s a go! Gregg Quote Link to post Share on other sites
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