BMC British Automobile is a company located in Isanti, Minnesota that restores and works on British cars. Although they install several different engines into many British cars they are best known for installing GM V6 engines into MGBs.
This 1974 MGB received one of BMC British Automobile’s conversions. They installed the 3.4 L L32 V6 and five-speed manual transmission from a 1993-1995 Camaro/Firebird using their custom mounts. This increased the car’s power from 87 hp and 103 lb-ft of torque to 160 hp and 200 lb-ft of torque.
The 1962-1980 MGB require different parts lists since body and cooling systems vary. Even air conditioning changes will cause the PCM, alternator, and ignition system to change locations and requires a different wiring harness. This is why BMC British Automobile keeps custom build lists according to customers’ requirements.
If you are interested in increasing power in your MGB you can send it to BMC Auto or you can purchase one of their MGB 3.4 L V6 swap kit. They also informed us they are developing a V8 conversion kit.
Source: BMC British Automobile FB page (more photos)
So it’s nearly 2 times bigger than original inline 4, yet it makes less than 2 times more power? The Smoking Tire has a video of Supercharged MGB GT, which made 112 rwhp. And I doubt that this thing will be much faster than that one, even though it has more power, since V6 added weight.
Your right this would weigh more due to it being a newer generation. That 1967 GT Matt says weighs 2,150 lbs with some online sources said up to 2,190 lbs. This 1974 roadster weighs 2,315 lbs. But a similar year (1967) roadster weighs 1,920 lbs due to it having no hard top. So a roadster model with the V6 swap in the same generation would be very close in weight with double the power.
MOPAR, it’s nearly twice the displacement, and it’s nearly twice the horsepower. Also, pretty much twice the torque. I don’t see a problem.
Hi MOPARfan,
The V6 weighs about 20-30 pounds Less than the MGB driveline, not more. When we are done with these, we switch the rear end gears out from the 3.909:1 to either a 3.31:1 or 3.07:1 plus we go to a 0.73 5th gear on average. At 60 MPH (2,000RPM @ 60MPH), you can drop it back in to third gear and move around traffic extremely fast or if you want, leave it in 5th gear and accelerate around the Supercharged 112BHP MGB. 🙂 We have had many people drive these after driving some of the MGB V8 cars and find these very comparable- some quicker. It may have 25% less cylinders than the V8 but that does not mean 25% slower. Due to fuel injection and gearing, the fuel economy is better than the stock MGB and for the average $4k supercharger bolted to an engine that was built for the supercharger at another $3k++ with a 5-speed conversion for around $4k, you can expect to have a car that lasts half as long, gets half the fuel economy but at least it is still the Austin ‘B’ series engine. The ‘B’ series are a good engine but everything has its limits, the popularity of the V6 conversion.
So what kind of rear ended is used with the V6 Camaro engine and the T5 transmission? Also what gear ratio should be considered in the rear and the transmission? I’m looking to get my B to move easily at 80 mph. Not sure what the top end will be with this setup. As u can see I’m new to this but plan to make thx change to my 67 roadster
What did you end up doing about your rear end and what gearing looking to do 80mph
When you state you change the rear end gears out, did you keep the original MG rear end?
V6 weighs less and will give you more gas milage
Actually, the V6 with transmission is lighter than the B 4 banger with transmission.
what was the rough cost of this conversion? just engine/tranny/ part.
Durant,
Let’s make a comparison:
MGB Supercharger from Moss: $4,300. Average 5 speed conversion that is rebuilt and ready to installs appears to be around $4,000. If you install a supercharger on an old engine, get ready to see it give out within a few thousand miles. Since the engine is not built to take it, it will cost more than the average MGB engine rebuild. Right now, not including the engine rebuild, I have already named over $8,000 in parts also not including new hoses, heater valves, radiators and other things that it will need.
Compared to the average V6 conversion, a DIY’er will have about $7,000 between a rebuilt T5 five speed, a used engine and all the bits and pieces to install it.
Everyone has a different requirement and different expectations but to give ‘as close to’ apples to apples comparison, you get the same weight, TWICE the torque which equals cutting the 0-60 time in half, a reliable car that gets better fuel economy and a lower engine speed meaning the car give powerful but more relaxed driving.
~ $7000 for all the parts for this conversion is a STEAL! Could you comment on the “average” labor costs, if your shop were to do this conversion?
The cost strongly depends on how you do it. Most expensive and somewhat easier is to buy everything “ready to go”in kit form. It is convenient, but expensive. Plan to spend $3000 for $1000 worth of goods. I make my own mounts, use the s10 bell housing so I avoid the HTOB, make a couple of simple brackets for the alternator and so on. I have had the exhaust manifolds made locally. The best is to get a whole donor car-although they are getting rarer-or, alternatively, get a well documented motor and transmission from a scrap yard or internet source. (e.g. car-parts.com). The motor can be a 2.8, 3.1 or 3.4. They all do quite well. (There is nothing especially magic about the 3.4 ; all this series motor really wakes up the MG and makes it roadworthy and fun to drive as a modern car.
Who sells motor mounts for a decent price to swap a GM 2.8 liter V-6 into a 1977 MGB. I don’t need a whole kit.
I think classic conversion engineering and BMC Autos do. I make my own. See my journals in MGEXP.com
What do you do about the wiring? I have done a Mini Cooper conversion and had to send the ECU to be reprogrammed then had to tune the engine. Do you have to reprogram the ECU or do anything special with the electrical?
I have a v6 3.4 conversion and my motor mount broke
is there any where to buy just the mount itself
Hi Otha. I recommend contacting BMC Auto or Classic Conversions Engineering about purchasing a single motor mount.
Scott. I pulled my engine out of my MGB this last Monday. I am at a loss as I compared the two engines. I notice the back of the engine to shifter is 29 inches. The back of the V-6 too the shifter is only 18 inches. That’s quite a bit of difference. Am I missing something as I’m told this is an easy swap. Thanks. Kim Butler
Curious as to which T5 you have. I have one from a Firebird/Camaro, and the engine/trans does indeed fit, though I had to relieve the firewall in way of the bellhousing bolts. if you have a T5 from an S10, the shifter is in totally the wrong place.
I now have a T-5 from a Camaro. Have the car running but I need to put a set of headers on it. I’m sticking with the stock rear end to see how it does.
Your right . Mine is from an s-10. I found out the Camaro shifter is about 11 inches mor reward. I go tomorrow to what I hope is the right transmission. I found one for 250 bucks. I am going to compare the two too make sure it works. It’s out of a 1989 Camaro with a 2.8 v-6.