Pro's and Con's re Superchargine | MG MGB Technical

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MG MGB Technical - Pro's and Con's re Superchargine

This winter I will strip and rebuild my 70B engine. I was wondering, which way to go, Rebuild using the usual path of Cam, Raised compression, Dual Valve Springs etc. etc. OR cleaning up the ports lowering the compression and bolting on a Supercharger.I haven't seen much on our BBS re: Supercharging
Just a question.
David

David W

As that popular credit card TV commercial often asks: "...so...what's in YOUR wallet?"

Me? I always favor the "K.I.S.S." Principle (= Keep It Simple, St_pid)

As in all things mechanical - they wear and need maintenance, and breakdown.

If your B is your daily driver - can you imagine yourself fussing with a seized or goofed supercharger
while stuck along a dark, snowy, Canadian winter highway?

I've never chatted with an MG owner with a blown B engine, but I know some guys with Paxton blowers
on their Shelby GT-350's - and the engine heat they generate is something to always be concerned
with during hot days. The cooling systems on MGB's do not have much in the way of extra capacity
and will have to be uprated.

Me? I'd vote for rebuilding the engine with HC pistons, mild cam & springs, a good balance job,
and mild porting, etc. By not supercharging, you can use the money you'd save to get another
used B engine to tinker with. Then, you'd have a ready spare in your garage.

If, however, I were to insist on including a supercharger or turbo in my B engine plans - I'd include
forged (not cast) LC pistons, a mild cam and springs, and a big radiator & fan. These items would
eliminate any thoughts of cost advantages, when weighed against a more conventional rebuild,
but then, it's all in fun, right?

Just my thoughts.

Daniel Wong

David-
ADVANTAGES
1) The car will go like stink.

DISADVANTAGES
1) Blown head gaskets
2) Beat up bearings
3) Broken rings
4) Detonation blowing holes in the pistons
5) Bent and/or broken connecting rods
6) Overheating
7) Bent drive shafts
8) Blown U-joints
9) Busted transmission gears
10) Need I go on?

Ask yourself these two questions:
"Do I live near a Drag Strip?"
"Do I want a car that will be slower than an MGB with a nice, reliable Rover V8 in it, yet be a monster to live with?"

Steve S.

Advantages:
As Steve said, It will go like a scalded cat.
It will be unique. As rare as MG's are, there are even fewer with any form of forced induction.
If you enjoy figuring out complex engineering problems and building things, it could be a fun project.

Disadvantages:

$$$$$$$$$$$$$$$$$$$$$$$$$$$$$

If not done carefully, you could turn your engine into a pile of scrap iron. The B-series engine was never designed for the kind of HP you could create. The bottom end might not take it. Even if done carefully, you could trash your engine.

More $$$$$$$$$$$$$$$$$$$$$$$$$$

The aren't many people out there who can help you if you have trouble. There are lots on this BBS and other internet resources who can help with a four-banger, even a built-up four.

Re-sale. MGB's are not marketed to mainstream buyers as it is, but a turbo or super-charger will further reduce the market. Someone who just wants a fun car for summer drives, but is not an enthusiast, won't want the complexity. An enthusiast may not want it, because of the lack of originality. Many of us are not originality freaks (some are), but there is a limit for many as to how far they will go with customizing.

The standard clutch and transmission may not take that much power. The rear end, however will probably leave the ground before you can destroy the differential. That's another problem; keeping that much power on the ground in a light car.

BTW, I wouldn't even think about doing it with wire wheels on the car. If your car has wires, change over to bolt-ons.

Last word:

Its your car and your money. If it floats your boat, go for it. These cars are meant to be enjoyed. If that means a supercharger, have at it.

Paul Noble

David,

I would agree with Steve
Do I want a car that will be slower than an MGB with a nice, reliable Rover V8 in it, yet be a monster to live with?
Option is available
http://www.hi-flow.com/HP2MGSuper%20.htm
but I would prefer to go this route
http://www.fallaclassics.co.uk/project_cosworth.htm
but a V8 gets there with a rumble.

Paul

Paul

Thanks Guys
I threw out the question because a friend and I, was saying that we handn't seen or read much about supercharging a B. Daniel, has a good point about cooling, B's are not known for the best cooling system, even when new. Steve, I know you are right and the head gasket issue is a valid one. Paul, resale is a question re: original versus modified. Paul H, you are 100% right re: Cosworth RS.this is something MGB should have gone for years ago.
My decision: I think I will not swim upstream and do the usual things, Port/Polish, Cam, Flat top pistons, Balanced etc.etc.
Thanks for all your in-puts. and
Merry Christmas and Lets have a great, (top down New Year )
PS The snow has just arrived at our Mt.Washington it's nice to look at it from the Living room window and not have to clear it out of the driveway.
David

David

Have been looking into supercharging for a while as i really like the idea of something that isnt "just another v8" as this is the most favorable route into raising power in a 'B'.

I would have to do an engine rebuild anyway, so this would be the point at which i decide. Thinking specifically towards the hi-flow kit available. Quoted power is somewhere between 150-180bhp although with adjusting boost, probably much more so. This is a bad 'bang for bucks' ratio but you do get something a little 'different' than your average run of the mill MGB.

Also, this power hike is nowhere near what some guys are achieving with v8's, so firstly i dont think there would be a problem with clutch, gearbox, rear end etc, providing in good condition. Any worries could surely be attended to by the v8 boys as anything they are using eg clutch types etc , would surely be sufficient for an SC equipped 4pot given the power hike we are talking of here.

Dave Munroe is an interesting guy and one who has fitted this kit and has some experience now of its behaviour. The one thing that worried me is how the car would cope on the weekly grocery run etc, Dave has some favorable comments on this aspect of a cars workload, although i am still thinking about this one.

Originality is not too much of a problem in terms of MG because factory MG's have been fitted with superchargers, although i dont think this ever stretched to the B series.

Fundamentally i cant see the probs with putting a sc on a b series engine, if it is done with the proper care and preparation that should be undertaken during any engine rebuild. Speaking to the guys you are getting the kit off of should provide invaluable information to suitable camshaft profiles, piston types etc for their type of SC, which should go some way to cutting back on the things that could go wrong as quoted by Steve S. These things would be more aparent if the SC was simply bolted on to a standard MG 4pot!! Again Dave Munroe has an interesting story along these lines.

One final thing in favour of a supercharged 4pot, is that it doesnt drastically alter the characteristics of the standard engine, more enhance it. Most people stick hi lift cams, reprofiled dizzys etc to their B's, i was thinking along these lines too, but this(depending on degree of tuning carried out) changes the driving style of the B from a lazy 'torquey' engine which pulls away from lower revs in most gears, to one that really only comes alive after 3000rpm. Fun, but not always practical - which is also why v8 conversions are so popular. Supercharging, should (in theory) give you both enhanced torque curve and better top end resonse...

Downsides

1) $$$$$$$$$ :-< This means i have to wait to experiment with this until i can afford to do it properly and thus save myself some hard work in the long run....

2) NOISE Doesnt matter what you do to a 4pot, it will never, ever, sound as glorious as a v8 on full song.....

~PHIL

Phil

David,
If it is in your budget to supercharge, go for it.
The modern supercharges are a far cry from the old Roots types the factory put on their two main bearing four cylinder engines. One of the problems with the MGB engines is a very poorly designed head (for HP anyway) that does not breath well, so in order make HP you have to run them at high RPM to get a ram effect through the siamesed (SP) ports. If you don't follow the Hot Rodders Creed 'If some is good then more is better and too much is just right' then you can build very streetable supercharged B. I would go for go for 4 or 5 pounds boost and a throttle body injection in place of the SU. That should give you a small increase in HP with a good increase in low and mid-range torque, so it will feel like a lot more power because you will feel it at lower rpm. With the driveability at lower RPM, I would execpt the bearings, rings, valve train, etc. to last longer than a engine making HP through RPMs. With the new style resin head gaskets, I ran my 11.5 to 1 race engine for a full season without a problem but head gasket problems can be addressed if they are encountered, same with cooling problems. The drive train shouldn't have any problems with the power your going to get as it handled the MGC six and the factory V-8s. As for resell, that will depend on how nice of job you do. I think you will find just as many buyers looking for a nice tricked up B as looking for an all stock car. Currently US vintage cars are going for higher prices as hot rods than stock.

Where is Pete? Pete supercharged a B in eastern Canada awhile back. I would like to hear his story.

Leland Bradley

Go for it. The B motor is more than strong enought to handle 6 psi of boost. For those of you who say it cant handle it, read the Grassroots Motorsports article about the guy who owns Pierce Manifolds 160 NA horsepower 5 main. He says itl go up to 8000 without a problem. The heads are a major part of the problem though. I would go for a crossflow head that way the exhaust and intake are on separate sides of the motor much like on modern cars. Modern superchargers do not seize unless they are neglected. Just keep to good oil change intervals and youll be fine. Run higher octane gas and dont worry about detonation. Dont run over 9:1 compression and youll be that much better in the battle against detonation. Make a blowthrough box for a single carb (weber or something) and play with the jets to get it right. I like BV8's but something different is great. Personally I like turbos and am thinking about building a turbo B. The only bad thing about superchargers that I will echo from above, the rapid wear of the front main bearing becasue the supercharger is belt driven. Good Luck.

Jarrod

David,
I've been running a blower on my '53 TD for about 2 1/2 years now, and I highly recommend it. The unit I'm using is the Moss Magnacharger for T-Series. (One of the advantages of working here). It is actually the prototype and I'm quite happy with it. So far, I've had no problems, except, as Steve S. said, a blown head gasket. I'm replacing it with one of our solid copper ones, which should solve the problem. I put the unit on a freshly rebuilt engine that was box stock with the exception of a Mallory dual point distributor. How did I manage to blow a head gasket? Well, I'm also Beta testing a "Big Boost" kit that has me up around 9 1/2 pounds. Of course, I don't push it that hard often, but when I do the results are quite staggering. No V8 can match the sound of a blown four at full screech. The blower itself is hardly noticable with an air cleaner fitted, but with a velocity stack on the carb, it howls like a Banshee under full boost. When initially fitted, the blower had 6-6 1/2 pounds of boost, which is what the stock system Moss sells has. At that boost rate, we dynoed the car. Rear wheel HP with carbs was 35.5...with the blower it was 59.9. That seems to me to be in the range of a 40% increase. Is it hard on the engine? Sure. Is it a kick in the a.. to drive a 100hp TD? Ya, sure, you betcha! (As they say in Seattle). What does a TD supercharger have to do with MGB's? Well...I was over in the Moss R&D shop the other day, and I saw the first prototype of the MGB blower mounted on an engine. We're anticipating having it available (hopefully) by late spring. It will use a modern Ford/Eaton rotor pack with a housing, manifold, carb and linkage all custom tailored to the MGB. I sold my own "B" about a year ago..it is now being driven by a 17 year old. When the blower is available, I'm going to have to get another "B" to bolt one on to. Driving a supercharged car is about the most fun you can have with your clothes on.

Craig Cody

Dave Munroe's car was mentioned in an earlier post. For a closer look at his supercharged mgb roadster, go to http://mgb.munroe.ca
Phil

Phil

Craig ....what your best WAG at the price range of the moss kit?

Kevin Lichterman

Jarrod- The OZ Han's Hotter ( his designed and built SC which Dave used) won't go on a x-flow .....yet. Hans has threatened to put the adaptation on his list, and I'm waiting for my 71 x-flow. In the meanwhile, I'm rebuilding a 1980 MGB to 8:1 and hoping to scratch up the scratch to buy that $4k OZ job. Wonder what the Moss unit will be like? Has craig waggied yet?

vem myers

Hmmm. Let me just run out back and disembowel a chicken to I can read the entrails. I'd say, based on what the T-Series costs, but with anticipated sales that will likely be more units, we're probably looking at something $2500ish. Hard to say exactly. If we are able to order the components in large enough quantities, we'll get a price break for the manufacturers which will, in turn let us price the kit at a more tolerable level. I'll keep you posted as I find out more.

Craig Cody

Hot Dog and oh goodie

vem myers

I would definately try to get the supercharger to work with the XFlow head. One for temp difference of the air charge and for the higher flow. I imagine that the XFlow and supercharger vs. normal head and supercharger would yeild more power.

Jarrod

Jarrod- Given my limited, one year experience with my x-flow conversion, the idea of supercharging that rig is compelling. I have a Burgess head on a sim engine rebuild, and the 2 seem to approach equity as the rpm level peaks. I've just broken in the Burgess build and both have been taken up to around 5700 RPM. The x-flow however is notably more gruntable at the lower-mid range where I usually run. This is hard data received as you are forced backwards as other traffic seems to suddenly slow way down and the sidelines blurr. To me, its been one of my better $1k investments: bang to buck. To include a supercharger now, would be the best. Happy New Year to all us wacko B guys and gals....Vic

vem myers

It has been done. See crossflow thread, and this link.
<http://groups.msn.com/WinnipegSportsCarClub/mgbghost.msnw?Page=1>
MGAdams

MGAdams

A lot of the comment about the problems relating to supercharging (eg cooling) are the same that you will find with normal aspirated power tuning. Despite what some say supercharging as route for increased power can be cheaper and simpler and more importantly more streetable than the normally aspirated power route.

Advantages are:

Bottom end torque increase
Mid range power.
You might find a Judson unit off the shelf!!
There are lots of good reference books on supercharging.
A close to unique car the envy of others.

Disadvantages are:

The installation weighs whatever X more than the normally aspirated route and it sits right at the front of the car and high up with it so has a handling penalty normally aspirated tuning doesn't have.

Most superchargers suitable for the B are going to be fairly RPM limited so to exploit the power for a higher top speed you might to need re-gear (even with o/d) to match peak power to a realistic peak speed (given the aerodynamics of the car)to peak rpm.

It can difficult to get good advice.

Daniel

Daniel- So wouldn't the x-flow Alloy head be a mate in heaven with the Super Charger, for its heat bleed-off quality?

vem myers

I would think so for the reasons you suggest and also because it will allow more boost/CR than an iron head. The cost of the conversion though is now even more expensive and the manifolding more complex/expensive.

Daniel

If you take a look at the cross-flow head, you'll see that the intake is on the opposite side of it's present location. I would think that this would mean an entirely different kit, definitely a different manifold and possibly even a different blower body. It would seem that an alloy "standard" head would give the heat disbursement advantages with all of the other aluminum head advantages. Keep in mind, that while a cross-flow might add some to the performance, I don't know that it would be a significant enough amount to justify the cost. A cross-flow helps with scavenging of exhaust gasses on a normally aspirated engine, but supercharging is forcing the good stuff in and the bad stuff out. Think about it, even a modest increase of 40% would put the 1800cc four banger almost at the level of the factory stock V8, which I recall was only about 135hp.

Jack Garr

Jack- Hans has just started marketing a 2.5 inch diameter header to go with his SC and get that "bad stuff" out fast. Claims 10-12 BHP increase ! on hiz OZ dyno ( but you know, down there everything flushes backwards)Vic PS- That was meant as a joke, I have nothing but admiration for Han's work and invention. Daniel- Yea, the cost can start looking ridiculous, but I am now searching for some SC, Roots or otherwise, arrangement to adapt to the x-flow anyway.Vic

vem myers

I would think that a x flow head would go perfectly with the supercharger. The main reason I suggested it is because by using that head, the intake and exhaust sides of the head are seperate, meaning a cooler intake charge. You couldd even rig up a small air to water intercooler and be able to run more boost and make more power. The skys the limit. The B block is a very strong tough peice of iron. Hell, it weighs the same amount as some V8's. As to the 2.5" header, that seems a bit large to me. You might make more horsepower with that set up but I am sure torque fell off a bit due to the loss of back pressure. The one thing that I dont understand about the company that make the X Flow head is this: If you went through all the trouble of redesigning the head to allow the X Flow action, why not get rid of the siamese 2nd and 3rd exhaust ports making way for even more power? Thatll ill never understand.
Me, I personally like turbos and would love to see something like that take form.

Jarrod

This thread was discussed between 20/12/2002 and 31/12/2002

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