tr62500 Posted September 4, 2011 Report Share Posted September 4, 2011 Chaps, I am thinking of converting my 72 6 PI to carbs. Having looked at some of the comments on the forum, it appears to be more reliable but not so sure on performance. Also would I need to obtain new inlet manifolds or could I use the PI units with modification. I assume I just need a blanking plate where the Metering unit was mechanically attached and a low pressure fuel pump. Any advice would be appricated. Regards, John Quote Link to post Share on other sites
Denis Posted September 4, 2011 Report Share Posted September 4, 2011 From what I'm told, SU's wouldn't deliver you as much power as the Pi or Webbers, and Webbers would need constant retuning and balancing by a Webber expert! Quote Link to post Share on other sites
Anschutz Posted September 4, 2011 Report Share Posted September 4, 2011 I have run my 6 with a saloon engine while rebuilding the original, it certainly loses a lot of the grunt but will tank along quite happily when up to speed and the bonus is another 10 miles to the gallon! Webers are in my opinion more trouble than the PI and thirstier! Best solution if you want to go carbs is to get the manifold and SU carbs and pump from a Triumph 2500 and the fuel pump will fit where the metering unit comes off, or just use a blanking plate and an electric pump. I think this chap has been around a few years and had a stall at previous IWE's might be worth giving him a ring. http://www.su-carbs.co.uk/phdi/p1.nsf/supppages/turner?opendocument&part=4 Quote Link to post Share on other sites
RobinTR6 Posted September 4, 2011 Report Share Posted September 4, 2011 I had a TR6 which had been converted to SU's, wasnt quite as quick but the difference was not as pronounced as often claimed. The MPG was 8/10mpg ish better. Its an easy conversion and the SU's will take some fettling to get them in tune ( an hour or so whne you know what youre doing), then its plain sailing. If your having trouble with your PI system that should be easier and a lot less expensive to sort than converting to SU or Webers. Whats the reason for the conversion ? Let us know as the guys here can help sort your PI out. Quote Link to post Share on other sites
foster461 Posted September 4, 2011 Report Share Posted September 4, 2011 Chaps, I am thinking of converting my 72 6 PI to carbs. Having looked at some of the comments on the forum, it appears to be more reliable but not so sure on performance. Also would I need to obtain new inlet manifolds or could I use the PI units with modification. I assume I just need a blanking plate where the Metering unit was mechanically attached and a low pressure fuel pump. Any advice would be appricated. Regards, John John, in addition to all of the other mods you will need the dizzy pedestal from a US spec car. My advice, dont do it. Get the PI sorted, it is too unique an induction system to be given up for carbs and there is no reason that it cant be made reliable without sacrificing performance or economy. The Webers (3xdcoe's) can be made to deliver equivalent performance but there is a big learning curve and a lot of expense (as a rule of thumb add 100% to the cost of the carbs and manifold) for dyno time and tubes/jets etc and that will be about what you will need to pay to get them sorted. Once they are set up they do not need to be continuously messed with as there are few moving parts or perishable components. Stan Quote Link to post Share on other sites
Guest ntc Posted September 5, 2011 Report Share Posted September 5, 2011 (edited) Do it Edited September 6, 2011 by ntc Quote Link to post Share on other sites
Phil Kirk Posted September 5, 2011 Report Share Posted September 5, 2011 John, It really is a matter of preference with carbs or PI. When I restored mine I decided to keep with the PI system but here is the the major factor I renewed everything, pump, prv, lines, mu, throttle bodies injectors and linkage not cheap!!. After about 800miles I had the car set up by Malcolm at Prestige injection. The car has done 12,000 miles with no issues with the PI, Starts and runs fine. I personally think most of the troubles people have with the PI system is that they fiddle with it once it is set up leave it alone. My car is a CP and is standard. Cheers Phil Quote Link to post Share on other sites
modelbuilder Posted September 5, 2011 Report Share Posted September 5, 2011 (edited) Do it The kudos with pi system is unfounded imho it is thirsty lacks performance unless std engine and not many can set it up right anyway.That is why its production was short lived . Now how many on here can say there car start's first time on all 6 cylinders?with Pi? the answers will be interesting Well here's my tuppenceworth. I have owned injected sixes for some 30 years and yes I have had some problems in the past but in the last 20 years since people like Martins Fuel Injection and now Prestige have been around to help, I find keeping the car on the road is no problem. I once foolishly bought an MGB V8 and found having the carbs rebuilt cost no less than replacing most of the PI system. I am lucky enough at the moment to run a TR6 with a Racetorations fast road engine coupled with a complete uprated Prestige system. It performs well and with a high torque starter, fires instantly every time,( as long as it has been used within say a week). If a couple of months has passed since last used it may take about 3 or 4 cranks otherwise no problem cold or hot starting. I have never driven a carb 6 so cannot comment on the comparison of performance but personally I would not consider the swap. The caveat obviously is cost but once any component in the PI system has been replaced, it should last for many thousands of miles. I have never priced a new pump, PRV, Metering unit and injectors in one swoop but still consider PI systems with today's quality stuff a reliable way of delivering the fuel. MPG ?? no idea but bet there's not much difference overall between the options. Rodders. Edited September 5, 2011 by modelbuilder Quote Link to post Share on other sites
Guest ntc Posted September 5, 2011 Report Share Posted September 5, 2011 (edited) del Edited September 6, 2011 by ntc Quote Link to post Share on other sites
Mk1PI Posted September 5, 2011 Report Share Posted September 5, 2011 Do it The kudos with pi system is unfounded imho it is thirsty lacks performance unless std engine and not many can set it up right anyway.That is why its production was short lived . Now how many on here can say there car start's first time on all 6 cylinders?with Pi? the answers will be interesting I run have run SU, stromberg carbs, Lucas injection and Megasquirt EFI on Triumphs Pi's can be run on an absolute shoe string budget if you understand the system and get your hands dirty - no offence to TR owners but I have found the saloon and associated owners to be the home educated PI gurus - they have rebuilt and understood the system in the past when the total car value was perhaps less than 1000 quid when an equivalent TR was 5000-10000 quid. Hence the "extremely frugal" saloon owners found ways of fixing injectors and resealing metering units and modifiying scrap yard Bosch EFI pumps to keep their trusty (rusty) steeds on the road. I had such a heap back in the early nineties - I actually converted one from carbs to injection and it got a good 32-33mpg around Europe at 70-80mph and would sit on 110mph in overdrive. So there is no reason that a combination of good parts and a little understanding of the system should not allow a reliable and economical car - I really think that Triumph set the units a bit rich on the first TR5's and well set up one today should get an easy 25mpg with 30mpg if driven gently (Tom Keys on the RBRR got 23mpg in a standard "150" car and drove like a mad man!) If you want to just enjoy the car and have no real interest in the fuel injection "legacy" then by all means fit HS6 SU's - with clean fuel and proper setting up they really are fit and forget. You lose a bit of power and a bit of induction noise and gain some economy if its done right. If you intend selling at some point keep the injection gear incase a future /ownernutter enjoys the challenge Quote Link to post Share on other sites
Mk1PI Posted September 5, 2011 Report Share Posted September 5, 2011 Now how many on here can say there car start's first time on all 6 cylinders?with Pi? the answers will be interesting That is the Question ?????? when warm or tepid you can go to any meet and hear them all,try it with yourself not in the car lean over from outside the car and turn the key Mine starts on 5 or 6 most of the time - whats the big deal - its part of the FUN - Quote Link to post Share on other sites
badshead Posted September 5, 2011 Report Share Posted September 5, 2011 Mine starts on 5 or 6 most of the time - whats the big deal - its part of the FUN - Yes, spot on. A few idiosynchracies is what makes owning a TR6 PI fun. Also, how many carburated car owners can push the choke fully in within a few hundred yards and then drive/idle smooth as silk? Quote Link to post Share on other sites
D1070 Posted September 5, 2011 Report Share Posted September 5, 2011 no choke required with the webers, just a few pumps on the loud peddle Quote Link to post Share on other sites
TRTOM2498PI Posted September 5, 2011 Report Share Posted September 5, 2011 PI is great. I have two TR6s that run Lucas PI, both with Bosch pumps. x3 Le-mans trips, x4 Round Britian Reliability runs - 2000 miles in 48hrs, and X3 10 countries runs - driving through 10 countries in 4 days. In addion track days etc. If they are set up correctly, and re-built components, they are fine. Yes, mine fires on 5/6 when warm, but will fire first time, with a little choke, then push choke in straight away. As per Andy, I got 23mpg (proper brim to brim refills), fully documented, driving at a GPS 80-90MPH with a 3:45 diff and A-type overdrive. Car was driven hard, 6k rpm unless on cruise. Throttle response instant. Cheers Quote Link to post Share on other sites
TRTOM2498PI Posted September 5, 2011 Report Share Posted September 5, 2011 (edited) PI is great. I have two TR6s that run Lucas PI, both with Bosch pumps. x3 Le-mans trips, x4 Round Britian Reliability runs - 2000 miles in 48hrs, and X3 10 countries runs - driving through 10 countries in 4 days. In addition, track days etc. If they are set up correctly, and have re-built components, they are fine. Yes, mine fires on 5/6 when warm, but will fire first time, with a little choke, then push choke in straight away. As per Andy, I got 23mpg (proper brim to brim refills), fully documented, driving at a GPS 80-90MPH with a 3:45 diff and A-type overdrive. Car was driven hard, 6k rpm unless on cruise. Throttle response instant. Cheers Edited September 5, 2011 by TRTOM2498PI Quote Link to post Share on other sites
Guest ntc Posted September 5, 2011 Report Share Posted September 5, 2011 (edited) del Edited September 6, 2011 by ntc Quote Link to post Share on other sites
Mk1PI Posted September 5, 2011 Report Share Posted September 5, 2011 Neil - you seem very anti PI - did yours catch fire No issues here with SU's , Webers , Lucas PI or EFI - all of them have their own idiosyncracies which is what it's all about. Quote Link to post Share on other sites
Andy Moltu Posted September 5, 2011 Report Share Posted September 5, 2011 (edited) Do it The kudos with pi system is unfounded imho it is thirsty lacks performance unless std engine and not many can set it up right anyway.That is why its production was short lived . Now how many on here can say there car start's first time on all 6 cylinders?with Pi? the answers will be interesting Swapping to SU's is likely to dissapoint. There's nothing fundamentally unreliable with the Lucal PI system - however it's easy to blame and easy to screw up by meddlers! It was dumped (by Triumph) because of cost (the fuel pump used was a cost saving measure that did compromise its relaiability in the early days) along with the ever more stringent emmisions regulations which is why modern cars use eFI. Webers are easier to tune (well there are more people thay know how to tune them compared to a Lucas these days) and generally will give a better power band when correctly set up - the Lucas PI system is notorious for a bit of a flat spot around 4000 rpm that takes a lot of minimising in tuned cars. The flip side is cost and fuel economy of a triple Weber set up as well as losing The TR5/6's unique character. Certainly don't waste time on Webers unless you put them on a hot engine. Edited September 5, 2011 by andymoltu Quote Link to post Share on other sites
roy53 Posted September 5, 2011 Report Share Posted September 5, 2011 Do it The kudos with pi system is unfounded imho it is thirsty lacks performance unless std engine and not many can set it up right anyway.That is why its production was short lived . Now how many on here can say there car start's first time on all 6 cylinders?with Pi? the answers will be interesting ME !!!! and its all Lucas, well nearly as i have a facet feeder pump Quote Link to post Share on other sites
Rob Salisbury Posted September 5, 2011 Report Share Posted September 5, 2011 Stay with the Pi system, just get it sorted properly, you'll learn to love it!! TR5/6 .. Pi ... synonymous you know it makes sense!! 25 years with one of the Pi saloons, I never once dreamed of converting it to carbs, I was proud of it being a Pi, and yes, at one time or another I had every part of the system into it's component parts. Once you absorb all the available information about the system it becomes infinitely tune-able for either power or economy and with some patience both. Cheers Rob Quote Link to post Share on other sites
roy53 Posted September 5, 2011 Report Share Posted September 5, 2011 So John what is your location ? and why not a member ? i have a full su set up from a 2500S if you decide on that route. When webers are set thats it,no more messing/tuning required. ROY Quote Link to post Share on other sites
Tom Fremont Posted September 5, 2011 Report Share Posted September 5, 2011 I've got 92,000 miles so far on a set of used-when-acquired DCOEs with no problems whatsoever, and no retuning ever. They will deliver the goods on a stock 150 engine ( if you consider that hot ) and my 1st recipe had nothing but a Kent TH2 cam ( mildest ) and c/r increase to 9.5 from 8.5. I took a lad from TRF's rebuild dept for a ride and he said it was way more impressive than his boss's TR5PI, saying " fuel injection didn't do much for that car ". That of course is debatable and I don't want to denigrate the P.I. because as seen above there are many fans of the system which has served them well, no doubt. Note that my views are informed by the complete absence of infrastructure over here to support the P.I. system and the fact that my cars didn't come with it originally. If I were in the UK I most likely would have stayed with the P.I. and never come to know the Webers ( ) I was treated to a comparison at Racetorations in 2006 with (2) Webered cars and (1) P.I. The carb cars ( which were of a higher output spec ) were smoother running on overrun, otherwise comparable. All were very tractable at low speeds. I'd like to hear of a Lucas P.I. kit that went as long without any maintenance . Then there's the altitude issue ( neighboring thread on that topic ) where Webers as well as other carbs are pretty much immune. I concede that calibrating them requires perseverance. I've done (3) different recipes on my '250s and each has been quite rewarding. As noted above, there are plenty of professional tuners in the UK who do Webers if you'd prefer to bypass the exercise; over here I'm on my own so had to sink or swim, and am pleased to report that things have gone swimmingly with mine. So enamored am I that I have (2) complete spare sets, vintage Italian, one NOS ( like the set on my concours car ) . I believe the fortunes of the TR5/6 may have been a good deal better had they been factory equipped with Webers given their simplicity, reliability and performance, but I can understand corporate politics prevailing . Emissions laws over here prevented the 150 BHP cam usage so the improvement would have been rather lower. Quote Link to post Share on other sites
Shezbo Posted September 5, 2011 Report Share Posted September 5, 2011 NTC Now how many on here can say there car start's first time on all 6 cylinders?with Pi? the answers will be interesting? Hi ya Neil, yep mine always fires up on 5 when warm, always good to start from cold though? Malcolm at Prestige has replaced most of my PI set up and this has transformed the car. There is a slight on-off tendency at partial throttle however this is easy to drive around, either get off the throttle on get on it! I WOULD however like to drive a car on Weber's...just to see - I have no loyality to the PI system-so I guess if webers were A1 I would maybe change? Quote Link to post Share on other sites
Guest ntc Posted September 5, 2011 Report Share Posted September 5, 2011 (edited) ME !!!! and its all Lucas, well nearly as i have a facet feeder pump del Edited September 6, 2011 by ntc Quote Link to post Share on other sites
david johnson Posted September 5, 2011 Report Share Posted September 5, 2011 I have no problem with PI once set up right. It seems OK for a couple of years and then needs a bit of tinkering again.There are no reliability problems generally. Problems are only caused by taking it apart and having to reset everything again.Starts first time on 6 when cold with choke, and first tme when warm with a bit of throttle if you get it timed just right.If left over winter it just takes a bit of turning over due to evaporation.I always thought Webers needed constant tuning. Having driven standard 150 cars whose power was disappointing I presume SU cars would be somewhat sluggish.David. Quote Link to post Share on other sites
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