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| 6 cyl Bristol cars Type 400 to 406 - restoration, repair, maintenance etc |
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09-03-10, 08:46 PM
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If you are going to vary the capacity and design of the new engine you should probably look at incorporating this into any survey of the potential market, because purists may be put off by something which moves too far away from the original.
Kevin H 
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09-03-10, 09:39 PM
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Bristol Engines
--- On Tue, 9/3/10, Bristol Cars - Owners and Enthusiasts Forum <webmaster@bristolcars.info> wrote:
From: Bristol Cars - Owners and Enthusiasts Forum <webmaster@bristolcars.info> Subject: RE: [6 cyl Bristol cars-t-396] Bristol Engines To: geoffkingston15@btinternet.com Date: Tuesday, 9 March, 2010, 20:46 (Please type your reply below this line!!) -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Kevin, .I think for this exercise and in respect of the survey you are probably right most will probably want to stick to the basic original specification but if Bristol themselves are going down the route of a 2.5 engine it has to be worth considering as an option. Otherwise as long as its based on one of the 100 series engines and does not cost an arm and a leg I am seriously interested in what develops out of all this. The BMW meanderings especially the V8 were based more on past than present thoughts. Geoff -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- (Please type your reply above this line!!) You may increase the space between the above lines as needed. ______________________ CURRENT MESSAGE FROM: Kevin Howard If you are going to vary the capacity and design of the new engine you should probably look at incorporating this into any survey of the potential market, because purists may be put off by something which moves too far away from the original. Kevin H ______________________ PREVIOUS MESSAGE FROM: Geoff Kingston 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. ______________________ This thread is located at: http://www.bristolcars.info/forums/6...l-engines.html To unsubscribe from this forum, please visit this page: http://www.bristolcars.info/forums/s...bscription&f=2 You may reply to this email to post a reply to the forum. You can also begin a new thread by sending an email to
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10-03-10, 12:55 PM
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Could this be a way of gaining the extra power without sacrificing any originality ? Is this possible / feasible or barking up the wrong tree again.
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11-03-10, 11:00 PM
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Cost Effective 2.5l "bristol" Engine
Enthusiasts,
If you are keen to build a cost effective 2.5L "Bristol" engine which looks very much like the "real deal" then you may like to consider the following: 1. Utilise a Triumph 2500 block and crank - strong,affordable,4brg mains, 75bore by 95mm stroke. 2. Cast a "Bristol" style - cross pushrod head utilising 3 IDA webbers (a la 12 port racing Bristol head) or 3 ICH carbs. Recall that BMW retrofitted their std block in the same fashion to arrive at the legendary 328 hemi head arrangement. In essence, you would be going down the same pathway! 170 bhp and suitable torque would be guaranteed- at a reasonable price. The key point being that the engine would look like a Bristol product! The bonus being that aftermarket TR to Celica or Supra bellhousings already exist. Brett
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12-03-10, 01:15 AM
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Cost Effective 2.5l "bristol" Engine
Why dont you just fit a TR engine , saves the cost of the expensive alloy
head, just don't open the bonnet at the Annual Concourse. Who will spend big money fitting a replica 2 litre engine to a Bristol saloon , I'd say no one . There are plenty of good used ones around from cars that have been wrecked. Only AC , Frazer Nash and Cooper owners might spend big money on a engine , but they are more likely to buy another tatty 405 and sent it to its grave for just a few engine parts that they will probably never use. Original blocks are always repairable , new cranks & other moving parts are available , original heads can be repaired . I think this forum talk about new replica engines will lead no where, but good luck anyway. When I got the Bristol bug about 35 years ago the BOCA members said it was impossible to get a 100 series engine , let alone a 100D engine . Within a few years I had 2 D engines and a 100A fitted in a Ace , Aceca and my 400 , then later a 100A for a engineless 404 . The same still applies , if you want one it's only a matter of looking , now it's so much easier with a computer & Forums like this. Save the planet and use existing parts. Geoff Geoff
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12-03-10, 10:17 AM
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Cost Effective 2.5l "bristol" Engine
Geoff D,
I agree that that the most cost effective approach to re equipe an engineless Bristol saloon would be to hunt down original gear and restore it. A couple of people on the forum broached the topic of a big bore 6 cyl Bristol engine ie 2.5/3L. My suggestion is just that - if you want a significantly bigger engine that looks something like the original without having to build the bottom end you may consider starting with something like a TR bottom end and fit a specially cast Bristol type head ( not an original Bristol head). As you well know, even Jack Brabham or Mike Hawthorn could not overbore a std block to 2.5L and get it to hang together! I would take a guess that a fully engineered 2.5L 100D2 engine (which I don't think exists) would require at least 40 000 pounds. A specially cast oversized head (for the sake of the argument, lets call it a 2.5L head) may cost 10 000 pounds. I know that I am oversimplifying the engineering problem and indeed ,the market/volume/unit price problem, but the TR route would have to save 30 000 pounds! I reiterate Geoff's question, how many people really want a bigger 6 cyl engine which looks like a Bristol if the complete engine and modern 5 spd box is going to cost (at a guess) upwards of 12 000 pounds? (engine and box not fitted to your car) Brett
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12-03-10, 11:39 AM
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Cost Effective 2.5l "bristol" Engine
Brett,
maybe I did not express my self clearly , but what is the point of a 2.5 - 3 litre TR block with a very expensive oversize copy of a Bristol head that will not fit in a Bristol chassis with major surgery , removing the gearbox X member and cutting the firewall & floors , new engine mounting brackets etc . The cost of all that would be greater than buying a 2 litre engine from one of the many wrecker / specialists . If you went the TR special head route you would only end up having re engined special that would be worth far less than one fitted with the correct Bristol six. The others that imagine they can make a 2 litre Bristol into 2.5 - 3 litre (and retain the same external dimensions) had better get their measuring tools out and have a good look at a 2 litre six's bore spacings , centre main sizes , crank , head design etc . I believe Bob Gerard in the late 50's removed the liners from a 2 litre block and ran special pistons straight in the block , giving about 2.3 litre . He used this engine in his rear engined Cooper Bristol with 6 port head running on methanol and reportedly produced about 190 - 200 bhp . Ivan Glasby in Sydney has this Cooper and engine but is now back to 2 litre , I doubt that Gerard could make it reliable. Geoff .
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12-03-10, 01:48 PM
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Cost Effective 2.5l "bristol" Engine
Geoff,
I am fully aware of what you outlined - I only offered a technical alternative to acheive a larger bore "Bristol" engine for those who expressed an interest. I am not arguing with you re relative costs of staying original vs the "big block" idea - I agree with you that staying original is cheaper -see my previous post. Re cutting x member etc, let's not forget that the 405's got the "gas axe" treatment from the factory to allow the installation of the laycock overdrive. Brett
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12-03-10, 05:55 PM
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Cost Effective 2.5l "bristol" Engine
If one was thinking about producing a new block and head one should
consider the weak points of the existing design and if it would be possible to improve on this without building a complete new engine. One point to think about is the amount of land between the bores especially between number five and six cylinders.(a hot area) If Bob Gerard removed the liners to increase the size of the engine it would have made the reliability a serious factor. Percy Kemish (responsible for the racing engines) told me the head sealing to the block gave them a problem with the racing engines although he did find a way to make the engines last the length of a race but this was always at the back of this mind. Food for thought. Bellerophon
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12-03-10, 07:36 PM
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Cost Effective 2.5l "bristol" Engine
Geoff
We don't really have to do the imagining on the 2.5Litre engine because Peter Jaye of Jaye engineering is already producing new cylinder heads and tells me that another very well known and well respected firm is or are about to produce new blocks for a 2.5 litre. version of the engine, which his heads will fit with, if memory serves me right, he said minor modifications. As to second hand engines these are neither as plentiful and certainly nowhere as cheap as the were years ago and while blocks and heads can be repaired and built up it does not get over the fact that the original casting are 50 to 60 years old and if nothing else weakened by years of use and probable corrosion of waterways etc. I don't see that producing. a replica engine or even the major parts to build one ether in standard or modified form for cars of the age is a waste of any ones time or effort. If you look at specialists supporting the Rolls Royce and Bentley market the practise is both widespread and well established. and for those of us who like to use. there cars frequently and enjoy their performance to the full the knowledge that people are making these parts, some to a better design that the original components and more able to stand up to modern road conditions is a great comfort. Geoff.
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12-03-10, 11:40 PM
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On Period Engine Options
Borgward Hansa 6cyl 2400 anyone? -see attached.
.....sadly, these well made machines are rarer than Bristols! Perhaps our German friends can elaborate. I believe that these engines developed approx 100 bhp in their final production form. Brett ps The enterprising owner of the attached car is running his machine on gas!
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13-03-10, 11:54 AM
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Hi, Just to add a few more observations regarding past attempts to enlarge the Bristol 6 cylinder engines by the likes of Bob Gerards , Jack Brabham Mike Hawthorn ETC.
My suggestion that a modern engine and cylinder head built to almost exact Bristol original specs.needs some clarification,When i suggested that the "New"2010 engines dimensions be altered a little i was well aware of the limitations that existed in the say 50s even 60s ,and those were no modern synthetic oils no computer aided design .less empirical knowledge ,This list could go on and on. One other area that has improved dramatically is the balancing of engine components by computer aided machinery. Some of the engine designers of the 40s50s60s era were incredibly clever futuristic engineers who in my opinion were at least 50 years ahead of their time, imagine what they could do with all the modern computer help/metallurgy that is now available. The engine i visualise if it ever happens would be externally identical to the present engine and would be available in more than one capacity,the customer could choose standard bore and stroke at one price and bigger bore or stroke at another price. There are endless examples of engines that have been made " big bore" and it was thought that the limit was found, using a Ford crossflow as an example at 1760 CC Only to discover later that someone managed to make them 1970 ccs.And who would have thought a 3500cc Rover V8 would eventually be more than 5 litres. Tom
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13-03-10, 02:40 PM
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Bristol Engines
Tom,
Re overboring cylinders whilst keeping the external dimensions of the block the same - I think that you will have insufficient sealing area between the bores. The original engine is already marginal in this area! The other issue, as correctly pointed out by Geoff Dowdle, is that a substantially overbored block from say 66 to 75mm diameter would encroach/erode your main bearing area of your block. In short, if you increase your bores to enable 2.5L or more you need a new longer block casting and crankshaft. Hence my TR 2500 engine block and crankshaft suggestion earlier. Can I suggest that you have another look inside any block and you will see what I mean. I guess you could design a "modular" engine with different stroke crankshafts and vary the rod length. Unfortunately the 6cyl Bristol motor is already substantially undersquare and thus increasing the swept volume by increasing the crank throw and fitting shorter rods would be a backward step in efficiency. I think that most designers just set out to optimise the bore to stroke ratio and allow say, a 3mm overbore capacity. Regards, Brett
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05-01-14, 04:59 PM
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Casting new block/head.
Might this new fangled 3D printing provide a cost effective way for fabricating patterns for heads and blocks? Anyone embraced this technology yet?
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16-02-14, 03:03 AM
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Jag Motor??
I must admit that I've been thinking of selling the motor and gearbox from my 401. Then possibly installing a 2.4 Jag motor, which I have. Hopefully not much weight added, as the 2.4 is lighter than a 3.4, though I have no info as to how much less.
Then the 401 would be driven more, with less chance of being stolen and gutted for a fake Ace, etc.
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16-02-14, 10:36 AM
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16-02-14, 06:15 PM
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Cars tub new head/block
Kevin
The clue is in the word "pattern". My (serious) suggestion was to consider using 3D printing to make a pattern of the needed part in plastic, not the part itself. Then use this in a mould to cast the part in iron or aluminium, using the lost wax process. Must be vastly cheaper than constructing a pattern using traditional processes. The Jag 2.4 is a straight 6 in the XK series. Fine design for its time, long stroke, a bit limp compared with its 3.4 and 3.8 litre brethren. You may be thinking of the small V8 that Jaguar fitted in the 250 and Dart. Nice, compact, but I think you may be right that it might be a bit tricky to slip into a Bristol. But maybe it's been done. Selling off the original Bristol engine and replacing it with another unit sounds sacrilegious to me. But if it must be done, why not emulate AC, and slip in a 2.6 litre six cylinder Ford unit from a Zodiac. It's what they did with the later editions of the Ace and Aceca. So not that awful, and there is a distinguished precedent.
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16-02-14, 11:07 PM
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19-02-14, 02:05 AM
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19-02-14, 12:08 PM
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InRacing in Nottingham seem to be energetically using new technology to simplify the manufacture of replacement parts in all kinds of impressive ways, so they might well be using 3D printing to make patterns. They do make new 2-litre heads and blocks already. The fitter who showed me all all this didn't know how much a new block would cost. It might be a matter of 'if you have to ask the price, you can't afford it'.
Hugh
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