1971 MGB Roadster - V8 Swap for 1.8 unit

[Packman]

Hi,

I will be taking my engine out of my MGB Roadster the comming winter to refresh the engine bay (Re-Paint etc) and was wondering how much work there is involved in fitting a V8 in its place?

Some of you must have done it? Is it a pain to do? and how much is it likely to cost me?

Can't afford a new unit so "good used" is the baseline.

Thanks

[na]

quite common loads of stuff about it on net, probably a few threads about it on PH, sure there was one not so long back

are you sure you've had the 1.8 long enough to get it up to best condition with full and proper servicing and regular driving, perhaps even rolling road tune-up (if all service work has been done)

or it could be that you just like the getting your hands dirty work

or like many of us have you bought one model and wished you'd bought the other

unless you want and enjoy doing the swap work it would probably work out less expensive to sell the car you have now and buy one that's already converted (or factory BGT) and has had all the swap and additional work done and has been shaked down and fettled

a V8 in a B isn't necessarily that fast or quick more about the torque - and petrol consumption for the faster V8s

ETA: and I'd suggest not taking the car off the road for too long in the winter otherwise you lose some of the benefits to the car and you of sdriving it regularly - and I bet there'll more pleasant weather driving days or oppitunities this winter than there have been
this summer

Edited by na on Wednesday 15th August 13:27

[williredale]

There's also a book called 'how to give your mgb v8 power'. Catchy title!

I'd echo what na said though about whether you do it yourself which sounds interesting or buy one which has been done.

[na]

williredale said:

There's also a book called 'how to give your mgb v8 power'. Catchy title!

I just couldn't remember the title of that book so left it out!
I've got an old and always was low grade brain

[900T-R]

Many moons ago, when TVR Griffths and Chimaeras were still very expensive on these shores, I did some research into this. The bottom line was that this is easiest to do starting from a 1976-on shell (you can always convert back to chrome bumpers) or the engine bay must be modified somewhat, that apart from this it's basically a bolt-in conversion as all parts are readily available, and that if done right the parts added up to a quite substantial sum that is not refelected in the value of a car someone else already converted...

[na]

the engine of course is one of the least important aspects, if you're inceasing the car's potential power and speed then obviously you need to factor in the cost of good condition or increased braking, tyres and suspension

then add in cooling, transmission and final drive, engine auxcileries, good battery(ies) and connecting cables, exhaust, alterations to existing car and probably other stuff I've forgot

ETA: front crossmember

Edited by na on Wednesday 15th August 13:24

[Packman]

Thanks for the info everyone.

Yes i enjoy working on cars and have the tools facilities and skills to do it. I will be taking the engine out late September to refresh the engine bay so thought fitting a V8 would be a good idea.

Not interested in the gains that it will give me although the torque will be nice. More interested in the bling factor as the rest of the car is just stunning and mechanically perfect and I want it to look impressive when I lift the bonnet too.

Will I need to change the Gearbox? I will get a copy of the book, perhaps that will tell me.

[v8250]

OP, a V8 changeover is not always as straightforward as some make out. It is relatively easy provided it's thought through. In addition to Roger William's book 'How To Give Your MGB V8 Power', there's also 'How To Power Tune Rover V8 Engines' by Des Hamill. Both published by Veloce and can be bought cheaply via Amazon.

Roger's book gives you all the tech data required for engine and gearbox spec's, and also, well proven requirements to suspension, brakes, exhaust options [read this carefully] and electrics. I have spec'd and budgeted for a V8 changeover at some time in the near future. I'll be using a 3.9ltr unit with R380 gearbox, some back-end mods, but, will be keeping lever arms for more original type handling. You will need to consider if you'd prefer block hugger manifolds or hole your inner wings. Personally, I'd route manfolds out through inner wings every time as you get far better extraction efficiencies, and, give increased under bonnet temperatures somewhere to exit.

Good luck with the project.

[na]

if you're going for a Rover V8 engine the 4.6 is the smoothest as standard with reasonable power, torque and speed without going over the top for the car - provided the rest of the car is balanced to match the engine

now you've admitted your a bling tart don't get all sulky if it's mentioned again

[v8250]

na said:

if you're going for a Rover V8 engine the 4.6 is the smoothest as standard

this is not the case. in std form the 4.0 units are accepted as being the 'smoothest' in power/torque curves, but, this also depends upon the unit running with carbs' or injection. one logical advantage with injection is ecu mapping on a rolling road where the results can readily provide increase in both power and most importantly, fuel economy. though of course one should not preclude a carb' based engine.

one area that can cause a percieved 'unsmooth' engine is how the v8 is installed. a little attention to detail at this point can reap big benefits. all 3.9-4.6 ltr unit front pulleys need to be modified to fit. in planning your project you should consider using a harmonically balanced/dampened pulley to be fitted at installation; this is strongly recommended. upgrading to a v8 engine should also include an engine balance bar as std fitment to 'balance'/restrict torsional movement. clive wheatley sells these at £50 each http://mgv8.homestead.com/bgeng.html.

OP, your original thread asked is there much to do to convert to a v8? have a good read of roger williams' book first as this will give you all the points needed to decide if the conversion's for you or not. there's is much to be said for fitting an 1860cc B series unit that will give you circa' 100bhp at the wheels [subject to driveline being in good nick'].

all mgb'ers know of the good work peter burgess does with his engines. an 'ecotune' unit really does give good perfomance; though without that glorious v8 music!. what is less known is that peter and team also build v8's. they offer ecotune heads for only £640 the pair which is very good value for money. see http://www.mgcars.org.uk/peterburgess/page18.html

hope the above is not information overload but there's a fair amount to digest when considering the conversion.

[na]

yes I should have qualified that, I'm no good at quick posts

the 4.6 injection is by far the smoothest feeling in my experience of owning (a few) and passengering in (many more) Rover V8 engine cars from 3.5 carb to 5.0 injection in different makes and models of car - my B conversion was with a 3.5 carb

I've also had a 4.6 injection engine in another car and just after a 3.9 injection in the same model of car, the 4.6 was just so smooth, neither went on rollers but I felt the difference and the 4.6 felt smoother to me in my opionion and style of driving and use of vehicles

and the ECUs would not have even been for the make or model of car just off the shelf with engine purchace

another for Peter Burgess for rolling road and selling and back up of 123 Dissys

ETA: v8250, it feels more natural to be back to our slighly diverging views

EFS

Edited by na on Thursday 16th August 13:59

[v8250]

na said:

ETA: v8250, it feels more natural to be back to our slighly diverging views

hello nigel, yes diverging views are often fun. it's true that there's no 'true' way of converting to a v8 as we've all got different perspectives, experiences, and targets of what we want from our cars; which i think is great otherwise we'd all be boring clones

interestingly, i keep hearing very good reports of these guys and their standards of workmanship. looking at their site it looks like they know what they're doing http://www.turner-engineering.co.uk/index.html

ps i'm quite useless with all these internet acronyms...what does EFS & ETA mean? i thought ETA means 'estimated time of arrival' or 'Euskadi Ta Askatasuna' [Basque Separatists]

[na]

we're almost agreeing as much as disagreeing now

nothing wrong with different views and experiences

the 'ETA' I wasn't sure about and had to look back on my posts! I put it there to mean 'edited to add' but it probably isn't a recognised one, I don't know I'm not that well up on t'internet speak myself

'EFS' you'll often see from me (when I eventually realise) it means 'edited for spelling'

RPI also get mentioned a lot for Rover engines but I get the feeling OP (original poster) wants to do as much work as possible himself

I bought my B conversion from an engineer and whilst it all worked fine, except one error, it wasn’t quite the finished article and (as a vast generalisation) it reinforced how certain engineers’ thought

[Robert Lees]

I have had a 72 bgt that finally got round to spraying up, hopefully start to put things back together soon,, however I have recently bought my first TVR , a 4.5 chimaera V8, and I was stood looking at the b's little 1.8 engine on the floor of my garage thinking hmmmmm, how easy would putting a rover V8 in it be??. Interested to know what U finally decide. I know mgb's make a nice noise but the rover v8 omg!

[SMGB]

I decided to keep the 1.8 and give it s bit more go. I now have 90+ BHP at the wheels with better fuel consumption than before. The car is a 1967 Mk I soft top so originalty balanced with fun was the aim. Foe V8 I think I would convert a later car, say 74 on if I was doing this. By then the engineers were finished with MGBs, it was the bean counters still making the factory crank them out.