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| 6 cyl Bristol cars Type 400 to 406 - restoration, repair, maintenance etc |
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03-03-10, 05:44 PM
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Bristol Engines
This will probably sound daft, but here goes anyway.
I was told that many 6 cyl Bristol's have had their engines removed, and these were then installed in AC's or FN's, some of which which are then raced. Some engines must surely get destroyed during racing, and what happens to these destroyed engines and does anyone know who may have one available. Thanks Hal 
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03-03-10, 08:59 PM
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Hal, that's probably why there are fewer engines than cars nowadays, but I wouldn't think that many get blown up now, because the ACs and FNs are becoming too valuable to race hard. But if they are blown up today they are probably repaired/rebuilt, because the engines have become so expensive.
Although I suspect the cannibalisation of 6 cyl Bristols is not over yet. Andrew Blow would probably have a good handle on the market for the engines. Kevin
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04-03-10, 12:25 PM
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bristol engines
I am a recovering Clyde`s 406 to my own house tomorrow. Alpine Eagle have re-engineered the engine bay ready for the four-cylinder Volvo motor and gearbox to be dropped in. Given the unavailability of the original engine and its expense, this certainly begins to make sense. Further, the reason Bristol abandoned the long serving in line 6 was that it was no longer powerful enough. (Incidentally, there is some very useful stuff about the Star/ Sapphire engine project and the attempts to make a new motor in Christopher Balfour's new book.) These Volvo motors are so readily available. Clyde got his out of a scrapper for very little. They are hugely tough and reliable and turbocharging gives the power boost that is needed. Add to that the fact that you can keep the weight distribution unaffected and Clyde`s project makes a great deal of sense. I can prepare some photos of the engine bay if there is interest. Peter
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04-03-10, 03:14 PM
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Guys, What i was thinking, was to get hold of a knackered engine, and then take it to some of my casting contacts and have copies made and see if i could have the block and other bits cast in the original alloy or maybe some newer alloy.
It was just an idea of the top as a means of sourcing new engines. Regards, Hal
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04-03-10, 03:21 PM
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Guys, What i was thinking, was to get hold of a knackered engine, and then take it to some of my casting contacts and have copies made and see if i could have the block and other bits cast in the original alloy or maybe some newer alloy.
It was just an idea of the top as a means of sourcing new engines. Regards, Hal
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04-03-10, 08:05 PM
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Bristol Engines
Hal,
I was thinking along similar lines and had preliminary discussions with a firm in the UK who had already produced a cylinder head of similar complexity to the Bristol head. The major cost is in the pattern making, rough guide to produce the fist head around £20/25k after that castings could be turned out, they thought, at about £450 to £600 each on top of which you would have all the machining costs. This puts into perspective the £7500 being currently quoted by someone who has taken the plunge and is producing small batches of new heads. Cylinder blocks are or will shortly be available from another source I am told for around the same price. Sadly the current value of the majority of the early cars simply does not I suspect for most of us justify that kind of expenditure . This is probably why when I recently advertised two complete 401's and two complete 403's for sale for £35k the lot the majority of calls were from people wanting to buy the engines and gearboxes. The AC's and Frazer Nash's are far more valuable and the figures stack up. The other problem is that you will need at lest one scrap head to start with to be cut open for the pattern maker to copy the internal as well as external features, plus a good one for reference, I suspect the same applies to blocks. I had thought about going out of the UK. to get heads made as I have family connections in China but now production is actually starting in the UK I don't think it is a gamble I want to take anymore. I would rather join other owners to see if a larger order or commitment to buy in greater volume could bring the unit cost down. To go the other route different engine and box I would be very interested in thoughts on ways of converting the earlier cars to disc brakes without sacrificing any more 406's'. Whichever way you go with your project I think the effort will be worth it. Geoff.
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04-03-10, 08:05 PM
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Bristol Engines
TT Workshops are offering brand new reproduction 100D2 engines for
GBP40,000 delivery 12 months from order. I assume the 12 months is needed for the poor enthusiast to save/earn the necessary cash!!!!! or do we need 36 months. Geoff
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04-03-10, 08:32 PM
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Hi As a very new to this forum"observer" but a lifelong fan of all things mechanical especially English made cars,A thought crossed my mind when reading this posting, Could these complex Bristol 6 cylinder heads not be simplefied ,What im suggesting is that the head be made of two castings which would far easier to manufacture and machine,yes i know they would not be original as also would a volvo engine and gearbox in a Bristol not be original.
The "modular" head im visualising could even have the option of OHC. I best stop now as i may be branded a heretic and sent to join a honda forum or similar, By the way I have found the forums very interesting .Regards Tom
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04-03-10, 09:18 PM
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Bristol Engines
That's nearly twice the price of a Melling V12 which might fit in the engine compartment of a 403, but how would you make it stop?
His V8 is light in weight and only 21inches long, wide and high, quite a compact unit and a hell of a lot more powerful than £40000 worth of re pro 100D2 Bristol from TT Workshops. If I needed 4 new engines for my lot I think I'd need about 36 years! Geoff.
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04-03-10, 11:25 PM
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Quote:
 But there must be market if they're offering them, but still !!! Quote:
Exactly mate. I think you've nailed it on the head. There seems to be a large reservoir of people who need engines, and would ideally like to stay as original as possible, but its so cost prohibitive. Lets be real,we are in the middle of a major recession, people losing their jobs, pensions being decimated etc etc. Its hard then to justify a big outlay of money for an engine, and that outlay then evaporates. In the real world, it cant be justified. The alternative is not exactly fantastic. Go for a more modern engine and gearbox, costing a fraction of the price, but losing some of the authenticity. But trying to find someone who will install a modern combo and do it effectively and properly, is not easy, as i'm finding. If i do go down the more modern route, i may try and record all the technical specs, and what was done and how, and post this information, so that other owners can if they want, go down the same route, knowing that it works, hopefully at a sensible cost, thereby making more of the older cars viable to restore etc. Hal Quote:
 Just joking. An interesting idea, and one i can keep in mind, and can mention to the pattern maker. Quote:
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05-03-10, 12:20 PM
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Hi , I have been thinking more about these Bristol cylinder heads( 6 cylinder) , in a previous post i suggested a" modular " head might be easier cheaper to make, castings mold patterns etc. would be less complex , also machining would be less complex,
A futher thought occured to me ,why not have the easy part of the head,the lower half machined from a solid blank of alloy .this may sound like a lot of work,but it is not nowadays when you consider the number of engineering companys that have CNC Milling machines and very highly trained operators, The CNC program only has to be created once. Regards Tom
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07-03-10, 09:48 AM
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Engine Survey
Quote:
To further this along, I have created a survey on the web that asks how much you would pay for a newly manufactured Bristol 6 (long block), made to Bristol standards using their blueprints? I am looking for critical mass, where we get X buyers prepared to buy their engine for UKP-XXXX. Then I intend to float this number so engineering firms can determine it is worth their while to bid. Actually, since I do not own a Bristol 6, I intend to pass this on to another enthusiast who does, once the survey creates the numbers. Volunteers please! If you like this approach, please pass the survey link on to the other clubs that use Bristol engines. If you can't find the survey on the web click here or copy and paste into your browser the following link: http://www.surveymonkey.com/s/GCZQ3TJ Claude Last edited by Kevin H; 08-03-10 at 02:56 AM. Reason: removed extra characters from end of url
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07-03-10, 09:10 PM
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Engine Survey
Claude,
The survey is an excellent idea but I can't seem to get the link to it to work it takes me to the part of their site that allows you to create a survey rather than answer questions, any idea what might be wrong or what I am doing wrong or is there another way to get to it? I will try and find the details of the firm I spoke to last August about the cylinder heads I put the information somewhere and the magazine their detail were in and of course can't find it! I suspect that currently it is not to difficult to get new rods pistons and camshafts but not sure about the crank and how many suppliers are out there. Nor am I aware of the current prices for those items, it would be interesting if anyone else dose know if they could give us some indication. The big problem is the lack of availability of heads and blocks, several people have apparently been talking about making or having some made but as far as I am aware only Peter Jaye has so far actually produced new heads , he will be doing them in small batches and I understand they will be to a better specification than the original, if memory serves me right I think he said they were lighter and stronger than the original and slightly deeper / thicker on the actual head face. When I spoke to him he mentioned that IN Racing were about to start producing blocks including a 2.5 litre version but I have not made any enquiries with that firm. In both cases I think the prices were going to be around £7.5k contrast this with some reproduction alloy heads I saw recently advertised for the. 6 cyl Austin Healey at around £2.5k and the effect of a larger potential market in unit cost is quite apparent, I suspect also the Healey head may be a simpler casting and easier to machine? Tom suggested in his posting alternative ways of making a head,someone more knowledgeable in these matters than me may know if it is possible to use CAD to produce the patterns for the initial castings and if this would work out cheaper than the traditional methods, this might bring the costs down a bit but as I said previously if production of the first casting including the pattern making works out at £20/£25k, and subsequent casting average out at say £500 each, a batch of 10 is going to cost £2500 to £3000 each before machining. on the estimated cost I was given. The only way to reduce this is if someone can be sure of selling a larger number. If you consider that a good 401 or 403 will probably make around £30000 for a really nice car I think that to be viable a new engine or kit of parts to build one up would need to come out around £15000 maximum to stand much chance of significant sales , coincidentally roughly the price of one of Al Mellings new V8 engines, an engine I am thinking about to put in one of my own cars. If the price were nearer £20000 then for me at least it would probably be the alternative engine route and at £40000 no way, I would rather buy a good used Brigand from Bristol Cars or a nice coachbuilt Bentley Mk6 or R Type! Geoff.
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08-03-10, 02:58 AM
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Quote:
Try this one http://www.surveymonkey.com/s/GCZQ3TJ Kevin
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08-03-10, 06:50 PM
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Bristol Engines
Thanks Kevin,
That worked fine lets hope enough people are interested to make this a viable and affordable project. Geoff.
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09-03-10, 10:52 AM
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Claude..Guys,
Its a great idea to come up with a pricing idea and a list of people who are in search of engines. Sometime in the next few weeks, i will try and speak to my contact about casting the replica heads and blocks. If he thinks that he can do it, then i'm happy to carry the baton, as i also know of some people who could machine the castings afterwards. What do people think about tinkering with the design to gain more power, 2.5 / 3 litre etc.
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09-03-10, 04:23 PM
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Bristol Engines
There is a reason that Bristol went to 2.2 liters and not 2.5. If you
bore out the engine that much you are looking at new piston designs, connecting rods, and most important a revised crankshaft. The fuel fog problem may dissipate with more space to suck in the fuel. I am a fence sitter on the project. If a new block were available would I buy one, it is price dependent. Do I want to commit myself today to buying one, no. I like the idea. Another Kevin
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09-03-10, 06:50 PM
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I have been following this thread with interest and would like to add an observation regarding engine capacity.The cylinder head at present when as standard has a certain intake port capacity/volume usually described in cubic centimeters( CCs)and has an ability to flow so many cubic feet per minute(CFM) All very basic stuff that applies to any engine.So if a new block was manufactured with a little more room/clearence for a longer throw on the crankshaft,or larger diameter cylinder liners , or both, then extra capacity maybe up to or even more than 3 litres would be possible.
Now the cylinder head with its siamesed inlet tracts will need to be able to flow more CFM to feed the extra capacity therefore the new head will need a slight redeseign to allow it to breathe better, all this = more hp. With some careful research its possible that con rods could be sourced from another engine,as Brabham did many years ago on their Repco FI engines,if memory serves me right those con rods were standard Daimler Dart 2.5 V8 items.Pistons are not an issue as custom pistons are available from numerous manufacturers and relatively cheap.The crankshaft could be sourced from many countrys nowadays. I look forward to others views . Tom
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09-03-10, 07:40 PM
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Bristol Engines
Kevin,
The last time I looked at Bristol Cars website in the section covering upgrades there was mention of a. 2.5 liter engine, I assumed that this was a conversion of the existing engine but when I was speaking to Peter Jaye about his new cylinder heads he told me this was going to be based on. new block castings. made or about to be made by IN Racing and that his heads would fit this block. Bristol Cars obviously think these problems can be overcome quite probably with the other additional new parts you outline, but I would certainly be interested in the larger engine option if it were available. Another thought but what about a project based on the Larger BMW engine that the Aldingtons wanted Bristol to use instead of the 328 unit, that must have been designed to fit the same type of chassis layout as the smaller unit, same probably goes for the post war BMW V8 though that may be even shorter supply than the Bristol unit. Geoff.
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