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MG MGB Technical - V8 conversion
| Hi guys, My MGBGT has 115BHP ATFW, but i want more. Oselli tell me that to get more BHP i will have to go upto 19600cc and shell out loads of money for small gains. So i was thinking that it may be a better project to do a V8 conversion. I am at the very early stages of research, but i was wondering if people who have completed the conversion before could give me some advice. Will i need a new box and rear axle? How easy is it to fit under the bonnet? How many new parts am i going to need? Where can i find out more information? AND HOW MUCH IS A 115BHP 'B' SERIES ENGINE WORTH? |
| joseph phillips |
| Jeez, your idea is really bushwhacking, no one's ever tried this before so I don't think you'll find much in the archives ... ;-) ... only givin' ya crap good heavens there's so much info on this topic out there in the world and in the archives and in the tome "How to Give your MGB V-8 Power" it's just insane. Every problem you're likely to face has been licked many times over so DEFINITELY read up. But it's a ton of work if you want to do it right. And why do anything if you're not gonna do it right? |
| Ted |
| Hi, i did a search but the threads that came up were of no use. So where is the best place to get information?? Cheers Joe |
| joseph phillips |
| For a start tune in to the V8 and V8 Conversions page on this BBS. Then buy the book Ted mentions. Its by Roger Williams and tells you most of what needs to be done. It's not completely straight-forward. What age is your car? It's easier on a rubber bumper car than a chrome one. Yes you need a stronger gearbox and yes you need a higher ratio (lower number) in your back axle. You also need a different radiator, speedo and rev counter, exhaust system and you really should upgrade the front brakes. You may also want to do something to the suspension. If you have a chrome bumper car, you have to alter the front bulkhead where the steering column comes out and the equivalent piece on the passenger side. You have to make the gearbox tunnel higher. You have to saw off the engine mountings and weld on different ones. You have to move the radiator support panel further forward. You have to alter the angle of the steering column and fit a smaller universal joint. You have to alter the crossmember that the gearbox sits on and you have to resolve the fact that the gear lever doesn't come up through the middle of the hole in the car. You will need a new propshaft. If you buy a Rover engine, it won't go straight in. You will need to alter the oil pump and oil filter, water pump, crank pulley, rocker covers and alternator mounting. Then you have to think about what carburation you will use - SUs or Holley or Weber or EFI, and you have to get it all under the bonnet with the lid shut. What about the exhausts? Many folk are now using RV8 manifolds which entails cutting holes in the inner wheelarches, but the old block huggers are still available. Two exhausts or one? One is simpler to organise as you can leave the fuel tank alone. I'm not trying to put you off - many folk have done this. I just don't want you to have any illusions that this is a straight swap, 'cos it ain't. Mike |
| Mike Howlett |
| Joseph, Start here: http://www.BritishV8.org |
| Dan Masters |
| Joe- The above comments by Mike are valid. The easiest cars to convert are the 1977-1980 models because they have the necessary dished wheel wells and the relocated forward radiator. Pre-1977 models can be converted, but it's much more work. If you want more than 160 HP, you'll need a different gearbox if you want reliability. Here is the USA we tend to use the Chevrolet Camaro transmission, in the UK the Rover transmission is commonly used. The Salisbury tube-type axle of your car can handle up 200 HP if it's in like-new condition. You might want to rebuild it with the stronger Quaife Engineering Limited slip differential and racing halfshafts. The project won't be simple, quick, or cheap, but you car will be transformed. |
| Steve S. |
| Joseph Oselli know their stuff, but with 115BHP at the fly, i think you have got room for more with your current engine (I seem to recall it is in a mild state of tune). Have you thought of speaking to other B tuners? Peter Burgess might help and also Peter Baldwin - you could do a google search for both. I would recommend you email both with your current set up (include as much info as you can) and ask if there are any mild improvements that can be made to gain more useable BHP. With a rolling road tune up session you may be able to squeeze a few more horses out of your current set up, but not only that, they may be able to suggest some further tweaks which won't break your bank. Can't help but thinking Oselli are selling you short by saying you need to spend a packet more on your engine. I have seen higher figures quoted on this board for various engines, which are essentially at a similar state of tune (i.e. like yours). Always worth a second opinion before you jump feet first into a v8 conversion..... Just a thought ~PHIL |
| Phil |
| Cheers Phil, I have abandoned the project already as it sounds like way too much work. I cant see how i can get more power out of my B. It has been on a RR and the only thing that Oselli suggested was that i bored it out to 1960cc at the cost of 1200 quid for about 10BHP. I will send Peter Burgess an e-mail, but i dont think anymore work can be done on the cylinder head. Cheers Joe |
| joseph phillips |
| Joseph, have you noticed the thread about supercharging in the MGB General BBS? There's also a link to the manufacturer“s site, and if I had the money, and didn't have about 1,002,006 other things to repair and/or install on my B, I'd go for it. Pricey, yes, but if the benefits are half as big as the mfr suggests, it would be a great buy. Just my EUR 0.02 worth... |
| Kari S |
| Joseph Well, for a start £1200 for a 1960cc engine is rather steep. You could buy a short block of this size from say Chris Betson for around half this figure and then transfer your head over. So for a rebore this figure is phenomenal! Also when it comes to modifying the head, you can essentially have the same things done to two seperate heads by two seperate machine shops but they will come out completely different, so there may be some room for improvement. Have you tried a cold air feed into the engine bay?? After my massive power loss in france this year due to the heat (my excuse and i am sticking to it), this is one of my next projects - i can't rememeber is exactly, but the figures are something like 1BHP for every 1'c that you lower the temp by.... Ok that example isn't going to give you massive power but it was a thought.... After that the improvement may come from tuning. I haven't had my engne rolling road tuned yet, but i sent my brother to get his mk1 cavalier to get RR tuned for his birthday. He went to Peter Baldwin in Cambridge (he races mini's with good success and is considered a genius with carb fed rear wheel drive cars). Standard tune for his car is 100BHP. With a new sports exhaust and about an ahour and half of peter's time, the car left with 115BHP on tap and goes like an absolute rocket.... When it went in, the car was running on our best result of about 92BHP i think. Good luck anyway... ~PHIL BTW to go the supercharger route you would need further cam, piston and CR changes to get yours closer to standard spec. And it is more pricey than the price quoted for the 1950cc - i reckon a better solution though! ;-> |
| Phil |
| Joseph, what you have to remember is that the MGB engine is an antiquated design first put into production in 1947. It wasn't state of the art in 1963 when the B was introduced, and another 40 years has passed since then. Yes, big gains can be made by careful head work but you are never going to get it to produce power like a modern 1800 can. Well not quite true, you can get lots of horsepower, but the car will be almost unusable as a road going vehicle with all the power high up the rev band and a complete bas**rd at low revs. Talk to Peter Burgess (there are links to his company on this website). He has so much experience of these engines. You need to be careful about big bore B engines as the cylinder walls become awfully thin and the gains aren't as much as you expect. Tuning follows the law of diminishing returns. The first increases are easily and cheaply gained, but each subsequent increase becomes harder and more expensive. If you want a flying machine, don't use an MGB, get a modern car. Use an MGB because you like the looks and it's a pleasant car to drive, not as an out-and-out performance machine. Mike |
| Mike Howlett |
| Joseph, You give up too easy! In truth, it's not all that hard to put a BOP/Rover engine into an MGB, well within the capability of the average backyard mechanic. Plenty of them have done it, the work has been well documented, all the parts and pieces needed are readily available at a reasonable price, help is just an e-mail away if you do run into problems, and there is an annual convention where you can go and get a first hand look at completed examples and talk to the converters first hand. When you consider the ratio of HP gains vs work/time/money spent, a V8 swap is hard to beat. 200HP out of your old 4-banger, if you can get it, will never be as satisfactory as 200HP from a V8, and you can indeed get that, and very easily. Any other changes needed to accommodate 200HP will be needed whichever route you take to get the 200HP. Putting on a turbocharger or a supercharger will add weight on the front end - sticking in a BOP/Rover will reduce weight. If you get 200HP out of your 4-banger and decide later that you want more, you're out of luck. If you want more out of your V8 later, go for it - up to 300 is easy to get, 400 if you want to spend the bucks (although you probably wouldn't be able to use that much power). C'mon, where's your American "can do" spirit? Go for it! |
| Dan Masters |
| Phil, Does Chris Betson have a website as i can't find it? I don't want mega power guys, just a bit more than i have at the moment. Cheers Joe |
| joseph phillips |
| Yep - sure do - just click on link above... |
| Chris Betson |
| Dan, The thing that is putting me off is that i am starting my last year of Uni in September so i dont have much disposable income and i need to concentrate on Uni work. When i have finished Uni then i will think more about it. Cheers Joe |
| joseph phillips |
| Chris, I have decide that i want my motor fully balanced and bored which will give it more torque, so making it more drivable and allowing me to put a higher lift cam in it. Is that correct Cheers Joe |
| joseph phillips |
| Are there any casting codes on the block? Are some blocks thicker than others? If yes what is the code for a thicker block? i know with the ford crossflow the use T1-T20 codes, t20 being thicker. Should i just exchange my block for one already bored? |
| joseph phillips |
| BUMP!! just keeping it at the top. |
| joseph phillips |
| Awaiting the flame I query: V-6? ( Bill Guzman @ KillerBee) |
| vem myers |
| Joseph Have you looked at a cross-flow head? FWIW |
| Martin |
| Martin, Ye i have looked at cross flow heads but they seem a bit expensive to me. I have a friend who can balance all my internals and get me some new cast pistons. All i now need to know is a price to bore my block, or a off the shelf bored block. Does anyone know anything about the casting codes?? Or are all blocks the same?? Cheers Joe |
| joseph phillips |
| >>>>Awaiting the flame I query: V-6? ( Bill Guzman @ KillerBee) not much point as we europeons don't use V6's!!! |
| Cecil Kimber |
| Joe, You are not going to get a noticeable increase in power without spending lots more money - at 115 bhp ( probably around 85 at the wheels) you are already getting 30% more than the standard engine with your 1868 stage 2 spec. You will pay between £725 and £1500 for a 1950 short engine depending on piston quality and still not realise all the power because the stage 2 head will not keep up - you will probably need to go for large valves and a 285 or even 300 degree duration cam to get another 10 to 15 bhp. The alternative is to fit an M16 twin cam Rover engine - these give 140 bhp with multipoint injection - just find yourself a Rover 820 in the scrapyard and use the engine - Roger Parker has done these conversions and can advise on the necessary parts and methods. Basically you need parts from an O2 Sherpa van engine and the whole job is a bolt in affair except for fabricating engine mounts and modifying the crossmember to take the oil filter. You can also use the Rover 5 speed gearbox which mates up directly to the O2 backplate which in turn fits the M16 block. I am looking at using an O2 Diesel oil pump with a remote filter to get round thsi problem but my project is on the back burner - I just don't have enough time to build engines and gearboxes AND develop new stuff! |
| Chris Betson |
| Cecil MG Rover do a fantastic V6 that I would love to see fitted to a B! Must away and find my flame proof suit..... |
| Martin |
| Martin, There are lots of MGBs being fitted with various V6 engines. Makes a real neat swap. Check http://www.britishv8.org to see some examples. |
| Dan Masters |
| >>Awaiting the flame I query: V-6? ( Bill Guzman @ KillerBee) vem, I'm disappointed. :- ( You didn't mention me! ;-) (BMC) I write when I have something to say... Or when someone brings V6 up.. LOL! Note that the flaming, albeit in fun or for war over the territory went both ways? About one or two years ago, we all got in some heavy discussions. We all enjoy our own, but expect the others to be fun as well. People talk about the K series in MG Bs and midgets and how this driveline is not availible in the USA. Well if I were to take a trip across the border into Mexico, they sell the new MGs down there.. A least according to the website. Anyways, this would lead me to believe that the new V6 would be availible there and thus to the US market for conversions... So those of us (V6 and V8) who convert have no excuse not to use the K series right? :-) OK, I can read spanish, but very poorly. Joseph, Obviously, there are many alternatives no matter which side of the pond your on. You will not want to use the stock MG gearbox for most conversions as it will show as the weakest link in the chain. The rear axle can be used and always changed at a later date when you have the ability (read time and money) to do such. You can make anything fit under the bonnet, you just might need more room underneath. You will need just about everything new. Well, maybe you can reuse your coil, fuel filter and pump for a lower powered carbureted version. Off hand, if the numbers run scare you or you do not have time- just add the supercharger from Moss or the Austrailian outfit. This is one item that should not depeciate too much if you decide that it does not have the power you are looking for. I think that the average Joe who does not wish to relearn (or really learn) his car would be best off with the superchargers. Not to discurage anyone from conversions, but conversions take time, money and may turn your hairs grey.. With frustration or from driving faster then the speed of light. FWIW, -BMC. |
| BMC Brian McCullough |
| Chris, I already have larger valves and a 285 piper cam and my engine is still 1798cc ( or quite close)!! Should i be seeing more power with this spec? Cheers Joe |
| joseph phillips |
| The main reason that i want to do this is because i want to use the car on some track days. If i cant get that much more power its ok, but i didn't think my B would like being thrashed around a track!! Thats why i am thinking of getting it balanced. Initially i wanted more power through a conversion, but that seems to be to much for me to deal with at the moment. Cheers Joe |
| joseph phillips |
| Joe where do you get your bhp figure from - flywheel figures are notoriously over optimistic - what is the bhp at the rear wheels?? I would be surprised if you notice much more top end power going out to 1868cc - but you will get more mid range torque due to the larger bore. |
| Chris Betson |
| Chris, My MG has been on a RR. Can't find the sheet at the moment but BHP at the wheels is 88.2, but i am not sure at what revs. If the engine is fully balanced will i be able to rev it a bit higher and make use of a higher lift cam?? Cheers Joe |
| joseph phillips |
| why not consider fitting a diesl engine with so many powerful units about. I would have thought a bmw deisl would put out nealy as much torque as the v8 and give better mpg. I am thinking of fitting a deisl engine to my mgb gt at some point although not being worried much about perfomance finding my current 1.8 ample i myself will probably just fit a peogoet engine or something. |
| jim |
| Joe, The standard engine will go to 6,200, fast road to 6,500, full race to 7,500 - which do you want? The issue is " is the engine still producing power at the higher revs?" and the answer is "it depends on the cam and cylinder head as well as timing". So fitting a wider duration cam with increased lift will increase the power band up to higher rpms - but you will loose power lower down the rev range. A BP 320 race cam won't idle well under 3000 rpm and will produce power up to 7,500. Balancing is always a good idea, fully balanced, with appropriate valve springs you should get to 7,500 before valve bounce sets in. |
| Chris Betson |
| Chris, The car is still going to be used mainly on the road so it needs to be useable on the road. I just want to be able to thrash it round a track and drive it home at the end of the day!! Do you do engine balancing? I am getting a few quotes for the job to see how much it will set me back. Cheers Joe |
| joseph phillips |
| BRY- Sorry bud, you de minnesota man on the v-6.Joe and Dan above are massaging the V-8 at 200 horse above and the 3.8 V-6 provides 215 stock and does not require wacking up the car. |
| vem myers |
| There is usually at any time, at least one v8 B on ebay. The price is usually reasonable. For the work and expense involved in the conversion, it's cheaper & easier to just buy someone else's project. Barry |
| Barry Parkinson |
| i supose so |
| lord lucas |
| Joe, No, but I have a man that does, around £100 for dynamic balancing. |
| Chris Betson |
| Barry- Which "e-bay" you been looking at? |
| vem myers |
This thread was discussed between 17/06/2003 and 26/06/2003
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This thread is from the archive. The Live MG MGB Technical BBS is active now.