MGExp

MG Engine Swaps Forum

Simplest modern MGB swap

Moss Motors
AutoShrine Sponsor
AutoShrine Sponsor
AutoShrine Sponsor
AutoShrine Sponsor

Tremelune Avatar
Tremelune Will Benedict
Los Angeles, CA, USA   USA
I had a '65 Austin-Healey Sprite a while back, and it was an extremely fun car to own and drive. I'm getting the bug again, and have been eyeballing MGBs to get a bit more highway capability, and because it seems like I can get a lot of modern comforts (reliability, torque, gears, high-power electronics) by swapping in a modern motor and transmission. I don't have to worry about California smog in a pre-'75 MGB, so I'd like to take advantage of that freedom to monkey with the motor. I also just like to mess with things. AC isn't needed, but heat might be nice. I'd like to use all stock gauges if possible. I'm basically looking to build a fair-weather, dailyish driver that will be nice to bump around town traffic in and run up the mountains from time to time.

I can piece together a car, and wiring/electronics don't scare me, but machining and fabrication are not skills or tools that I have. I'm interested in doing an engine swap with as little of that as possible. It'd be neat to have an I4 twin-scroll turbo in there, but from what I've read around here, it seems like the easiest swaps are the Rover V8 and the 3.4L GM V6. I found Bill's kit here, which seems like the ticket. I suspect the old V8s are heavier than the new V6s and don't put down more power anyway...

I don't know my High Value motors from my High Feature, 60°, or EcoTec3 motors, and I realize that "3.4L GM V6" can refer to many...I mostly know that FWD versions will take more work than RWD versions, so it seems wise to go the latter route. 200hp would be plenty (for now winking smiley ), and light weight is always nice. The car could see 40°F temperature and 8,000ft elevation swings in the same drive (seriously), so modern EFI seems very beneficial. Is OBD2 still a concern, or are their aftermarket EFI kits that get around those closed boxes (or maybe there's a way to trick them)? It seems like (possible OBD2 issues aside), I'd want to go with the most modern RWD 3.4L GM V6 available that will fit the kit, no?

How much custom work needs to be done if I bought every kit piece I could find? Let's say the motor is free. What would be the best one(s) for me to use?

Are there any model year considerations? I like the early cars for the steel dash, but the later cars for the stronger axles and (relatively) modern amenities, though I won't go later than 74.5.





Edited 1 time(s). Last edit at 2018-04-10 04:29 PM by Tremelune.

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
converse212 Avatar
converse212 Eric Morgan
Atlanta, GA, USA   USA
1958 MG MGA
1970 MG MGB "Daily Driver"
1970 MG MGB GT "Rusty"
1971 MG MGB GT    & more
Are you set on an engine swap, and have you driven a stock MGB? They’re relatively capable in stock or slightly modified form, and that is without a doubt the lowest cost, simplest option



Daily driving a '71 MGB

Resurrecting a '58 MGA

BMC Avatar
BMC Gold Member Brian Mc Cullough
Minneapolis, Minnesota, USA   USA
I agree, the Austin B series engine in the MGB can be a very nice engine in stock form in the right circumstances. Highly enough tuned and it should have decent power, especially for flatlanders like myself. It still requires better gearing- an overdrive or a rear end change or both. I believe a 3.7 rear plus a 0.82 overdrive combo would help out alot for the average MGB owner determined to keep the car in a fairly standardised form. My Dad continues to run his B Series and I would love to have another 1800 in my someday on the road MGA.

Adding a supercharger adds about 30 pounds to the driveline and about 30 foot pounds of torque and removes at least 5 mpg. In comparison, the average 3.4L SFI V6 is getting around 30mpg, removes 20-30 pound of weight from the driveline after adding a 5th gear and has more torque just off idle than a supercharged MGB has Anywhere in the powerband. You can drive it poorly and still out accelerate a half way decent supercharged MGB and not strain the engine.

You show that you're location is Los Angeles which shows over 4,000 feet above sea level and surrounded by mountains. Driving in stop and go traffic is probably fine in the MGB but once you get out of the jamb and into the hills, that may be another story.

My wife and I drove her Neon Sport up to the top of pikes peak and through the mountains and I was impressed at how much power is Removed up top. Even at elevations above 5,000, I could feel quite a difference in that fuel injected 2.0L with a car that was under 2500 pounds. I've had an MGB 3.4L SFI V6 just like the red one in Will's post above with the exact same engine build, computer tune and everything as the one above (we built the one in Will's photo as well), to 8700+ feet above sea level or so when we drove it to the owners residence from Minnesota to the west of Denver. Although I could feel a drop in the power of the 3.4L in a 2200 pound MGB, the power loss wasn't anything like it was in any other car I've had through the mountains. One of the neat things about a good build is that Compared to a stock MGB driveline, a properly built V6/V8 conversion has so much torque that both 4th and 5th gears are overdrive and any gear has more power at a wider variety of engine speeds than a supercharged MGB would have- plus the conversions give better fuel economy too.

I am Bias as our company offers components mostly for the 3.4L SFI engine but do support other engine types too but the 3.4L still makes the most sense. The reason I say that the 3.4L has been the best is several factors-

*it fits in the MGB engine bays decently. Late model 77-80 use the stock radiator and require no engine bay modifications. The 75-76 require no engine bay modifications but should get a better radiator- not required but very helpful, the 68-74 require removal of engine mounts, a point on the firewall either needs to be dressed or a scalpel taken to it followed by a fairly small amount of welding (that can be done with a portable welding set).

*It offers 160 BHP and more importantly 200 foot pounds of torque. That rating is probably spot on to just a little lower than it actually is, but GM wasn't overrating their engines. This pushes a decent MGB probably somewhere around 0-60 in 6 seconds. If you want a car that does it realistically in 5 seconds, your going to need a lot more engine AND a lot more car with far superior traction. Large engines are nice but of no use without $5,000 or so spent on the rear suspension, wheels, tyres, limited slip and so on.

*If desired, all the major donor pieces can be pulled from a single car. Personally, I find/purchase my used parts from car-part.com but a complete 1993-94-95 Camaro or Firebird with the 3.4L engine can be had for as little as $350. I just found one 2 hours away from me in Eau Claire for an asking price of $400 running/driving but rusted out. Craigslist.

Going back to how easy something can be is depending on parts suppliers, what has to be done to the engine bay as well as skill level and tooling. For the MGB, there are suppliers for the previous generation Ford V8, the BOP/Rover V8 and the GM 60 degree V6. If you are interested in the GM 60 degree V6, give me a call and I can talk to you about the various things possible and get a price list for your conversion along with what you will need in order to take something like this on. There are a lot of people who have completed this conversion that can also speak on and off the messageboards for the various conversions and those who offer them and I encourage you to find out more from those who have been there before you as well.

-BMC.


Member Services:
Minnesota's only Fully Dedicated British Classic only shop providing Professional Restoration & Services & Specialty Products including- proper L.E.D. tail lights, Wiring looms and Engine and five speed Conversion Kits
1744 Avatar
1744 Gold Member Bill Guzman
CA, USA   USA
1973 MG MGB GT "Renegade I GT"
1974 MG MGB "Renegade"
Give me a call, I am 60 or less miles away.
Located in Camarillo Ca.



It is our attitude that will determine the outcome


Member Services:
MG Classic Conversions V6. Wilwood brake dealer.
V8MGBV8 Avatar
V8MGBV8 Carl Floyd
Kinggsport, TN, USA   USA
In reply to # 3714427 by Tremelune I suspect the old V8s are heavier than the new V6s and don't put down more power anyway...


That sentence can encompass way more engines than you intended. Depends on which old V8s & which new V6s.

Not too many are going the FWD route because it is a bit more involved swap. It is lighter, though.

The Buick/Rover & GM 3.4 V6 are very close to the same (& a bit lighter than stock). Although, the Buick 215 is a smidge lighter than the other two. The Ford 302 is a bit heavier than stock (15-60 lbs depending on parts selection).

As has been said many times here in the past, this small variation in weights is a non-issue. It will not be felt in the handling of the car by 99% of the drivers.

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
Tremelune Avatar
Tremelune Will Benedict
Los Angeles, CA, USA   USA
My reasons for a swap are less about power and more about reliability, low maintenance, and modern convenience (though horsepower is always nice). It seems like similar time/money to swap in a full drivetrain from a wreck as it would to get a stock MGB and upgrade the generator to an alternator, swap in an overdrive or 5spd, add an electronic ignition, cobble together an EFI system that's more reliable than well-tuned carbs, etc—and that's assuming the 40-50-year-old motor is in top trim...I'm not interested in messing with a carburetor or points ever again.

I did not realize the pre-'75 models had different chassis than the later cars. That gives me pause, as it seems like converting a rubber-bumper car to the older style is just as involved as swapping in a modern motor, and I prefer the look of the earlier cars.

When I say V8, I mean Rover V8, because my understanding is that it's fairly drop-in due to it having been offered from the factory at one point. A Ford or LS swap seems like it would be a whole lotta fabrication, measuring, fitment, adjustment, trial, error, etc...In terms of V8s, I can't see too many reasons to go with anything other than an LS3 if you're going the route of fully custom fabrication to get it in there...That's not a road that is fun or cost-effective for me, however.

From reading around here, the 3.4L V6 is the "easiest" modern engine swap. Which 3.4L V6 do people like for this application? Is there something special about 93-95 motors? As they're over 20 years old, it seems strange to go through the trouble unless they're much easier to get installed and sorted vs a motor that's 5-10 years old (such as the LA1 or LX9). What about GM High Feature motors?

This is all helpful; I appreciate everyone entertaining my ruminations.



Edited 1 time(s). Last edit at 2018-04-11 11:22 AM by Tremelune.

BMC Avatar
BMC Gold Member Brian Mc Cullough
Minneapolis, Minnesota, USA   USA
The gearbox tunnel was widened for the 1968 model year and carried on to 1980.
The firewall was widened (slightly) for the 1975 model onward.
The radiator was moved forward for the 1977 model onward.

If the work is the the easiest on the 1977 and later cars, the 1975-76 is slightly more work but hardly worth speaking of. The 1968-74 cars, there is a little firewall work to do but its not doom and gloom, just takes a few hours to peen or cut and weld.

The 1967 and earlier are the cars that require more, but it's not the end of the world, just not something to take lightly.

-BMC.


Member Services:
Minnesota's only Fully Dedicated British Classic only shop providing Professional Restoration & Services & Specialty Products including- proper L.E.D. tail lights, Wiring looms and Engine and five speed Conversion Kits
Ichi Avatar
Ichi Scott Martin
Kenora, ON, Canada   CAN
Will,
The L32 or 93-95 3.4L engines are the rear wheel drive application. The LA1 and LX9 are front wheel drive. Earlier than 93 the Camaro/firechicken had a 2.8L and there may have been a 3.1 in there somewhere before the 3.4. So the 20 yr old 3.4 is actually the best rwd already. In terms of cost, a full 93-95 Camaro junker doner is best- get all the goodies you can from it then turf the shell. You can even use the stock PCM and wiring harness. More is needed for the fwd applications than the rwd ones and the cost is a bit more- provided you don't rebuild the motor. Once you factor in the cost of rebuilding the rwd 3.4, it would be about the same as just dropping in a newer fwd that won't need a rebuild. (not saying you actually NEED to rebuild the motor, but some do)
Scott

Tremelune Avatar
Tremelune Will Benedict
Los Angeles, CA, USA   USA
Aaah, gotcha. That makes sense.

Presumably the LLT/LFX "High Feature" 3.6L V6 used in the Cadillac CTS and later Camaros has a block that is incompatible with the kits available?

V8MGBV8 Avatar
V8MGBV8 Carl Floyd
Kinggsport, TN, USA   USA
That is a whole 'nother animal.

The LFX may well fit & be the swap of the future. You will be blazing the trail, though.

You did say simple. The 3.4 into a '68-'74 MGB would fit your bill, quite easily. Personally. not a fan of the pillow dash. There would have to be a glovebox mod, there. Or, steel dash retrofit.



Edited 1 time(s). Last edit at 2018-04-11 02:21 PM by V8MGBV8.

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
BMC Avatar
BMC Gold Member Brian Mc Cullough
Minneapolis, Minnesota, USA   USA
So here's the best way to do a conversion:


First start with a car.

You're in California so rule out 1976-80.
The 1967 can be done but it's not as easy.

That leaves 1968-1975.

If you do not plan to change the body and you only want chrome bumper, that removes the 1974.5-1975.

Okay, now we're down to 68-74.

Get the car, then the engine choice can come next but if you are trying to watch how much has to be modified then the GM 60 degree is probably best and the easiest is the Camaro/Firebird 3.4L.

-BMC.



Edited 1 time(s). Last edit at 2018-04-11 02:51 PM by BMC.


Member Services:
Minnesota's only Fully Dedicated British Classic only shop providing Professional Restoration & Services & Specialty Products including- proper L.E.D. tail lights, Wiring looms and Engine and five speed Conversion Kits
200mph Avatar
200mph Platinum Member Mike Joy
Winston-Salem, NC, USA   USA
Easiest, cheapest route: . . 1977-80 MGB (cheapest to buy) and Camaro 3.4 V6 and 5 speed, Guzman kit.

If your state has smog issues, use an earlier donor, knowing chrome bumper cars will cost more than rubber ones in equal condition

Forget about a 67 or older donor... prices have climbed to where a V6 transplant would devalue one, and, you do want the folding top, side door beams, collapsing column, etc. that come in the later cars.

I've experienced both Bill's kit and adapting a more modern (2006) FWD V6. Stay with the older motor. Easier to adapt, no special wiring or plumbing, bolt-in install.

Before you start acquiring, take a ride to Camarillo and see Bill. He is a great guy, a wealth of knowledge, will steer you straight, and has a running example you can look at.

(Same would apply to Brian if you were closer to him.)



"Have you ever thought... Everyone driving slower than your MG is a MORON, everyone driving faster must be a FREAKING IDIOT!". . . George Carlin

Ichi Avatar
Ichi Scott Martin
Kenora, ON, Canada   CAN
Will,
One thing I forgot to mention with the Camaro/Firechicken route, and it doesn't apply to the original question of motors, but...... transmission. The v6 t5 has a 1st gear ratio of 3.75 making it pretty much useless with the 3.909 rear end of the mg. The v8 version is much better suited with a 2.95 ratio. So you can still use the v6, just be aware that you may want to swap out the rear gears for something better like a 3.31 or 3.07. The mustang transmissions have a 3.35 1st gear so it's pretty much the same as the original 3.33 mg. In my opinion, cheapest is the v6 t5 from the donor, better is the v8 t5, and best would be the v6 t5 with a 3.31 or 3.07 rear gearset. (3.07 would give you a better 1st, but o/d would be really tall)
Scott
P.S.
Stock gauges need re-working but can be used. There are post in the archives about putting in a resistor or something for the tack, and I believe Jim Blackwood posted a nice workaround for the speedo using the Camaro speedo cable.

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
V8MGBV8 Avatar
V8MGBV8 Carl Floyd
Kinggsport, TN, USA   USA
IMO, a Firebird is not & never was a chicken on fire. I am not a huge Pontiac fan, lean more towards Chevy & Camaros. I can't help but wonder if the Camaro boys coined that silly, derogatory phrase.

BMC Avatar
BMC Gold Member Brian Mc Cullough
Minneapolis, Minnesota, USA   USA
In reply to # 3715268 by Ichi The v8 version is much better suited with a 2.95 ratio.

If this was all that there was to your statement, I would say this is wrong. The 3.4L or any engine that has a power band between idle and 5,000 RPM or so and at least twice the torque of the stock MGB, which has about 100 foot pounds at its peak.

If this was a 9,000 RPM power band engine with no real power below 3,000 RPM, it might be okay.
(practical power where you use it on the street and can gear it the same to use it on the track all the same!)

Why?

The V6/V8 engines we are talking about for the conversions are high torque engines but do not rev to kingdom come. Instead, gear it correctly.

Why is the V8 T5 a BAD item?

The same reason it is for the original MGB 1.8L engine except now the car has TWICE the torque...

1- it goes through the gears in about half the time
and
2- in this case, it's all about 4th gear.
4th in the stock MGB is 1:1 (that means one-to-one)
4th in the V6 T5 gearbox is 1:1
4th in the V8 T5 gearbox is 1:1

Since the peak torque of most of the engines we are talking about is say between 3200-3800 RPM, this puts you right AT the torque peak, not under it. 4th is pretty much useless to downshift to when your running along at 60 MPH.


For the 3.4L, I have had extensive experienced the following ratios:

GM V8 T5 with stock rear end (with several different 5th ear ratios)
GM V8 T5 with 3.73 rear end, 3.42 rear end
GM V6 T5 (both 4.03 and 3.76 1st gear) with 3.31, 3.42 and 3.07
GM V6 T5 with stock rear end.

When I break these down per car, I count about 10 different ways we have built.

There are items that change the formula- camshaft, vehicle weight, mountains or flatlands, mostly city/highway/autocross and so on but the engine has so much power that I will tell you that when your ready, call me and I would talk to you specifically and split hairs with you at that time.

LEAST and MOST satisfying system: V6 T5.... Phase I: least but very easy to take a year to drive the car first and then about a year or two later, Phase II: change the rear end gear ratio.

Satisfying until you have 100 miles on the car and realise that O-N-L-Y 1st and 5th gear are acceptable: a GM V8 T5 with a 2.95:1 first and if your lucky, a 0.63:1 fifth gear.


Going back to what you said:
In reply to # 3715268 by Ichi In my opinion, cheapest is the v6 t5 from the donor, better is the v8 t5, and best would be the v6 t5 with a 3.31 or 3.07 rear gearset. (3.07 would give you a better 1st, but o/d would be really tall)


That I agree with and I have several Very long write ups on this forum, most of which can be found by searching something like V6T5 vs. V8T5 with/without spaces.

Bad Gearing makes for a very poor car, mediocre gearing such as a V8 T5 with a stock rear end is bland but good gearing such as previously noted, gives the car a great feel and Compared to a stock MGB, when geared right, the conversions basically have ratios of both 4th and 5th that are essentially overdrives but hitting the throttle, the engine speed is low but if a person was deaf and had no cabin vibration either way, wouldn't be able to tell that it was overdrive due to the performance.

-BMC.


Member Services:
Minnesota's only Fully Dedicated British Classic only shop providing Professional Restoration & Services & Specialty Products including- proper L.E.D. tail lights, Wiring looms and Engine and five speed Conversion Kits
. Hide banner ads & support this website by becoming a > Gold Supporting Member <

To add your reply, or post your own questions




Registration is FREE and takes less than a minute!


Having trouble posting or changing forum settings?
Read the Forum Help (FAQ) or contact the webmaster