Supercharging - Formula For Success?

I'm finally getting ready to rebuilt the engine in the '65, and it will receive a Moss Supercharger during the project. To anyone who has built a purpose supercharged engine, can you list the details of your setup and the pros and cons you have run into? I have many factors I'm considering from heat to originality to performance to components and would appreciate any information you can provide.

This will be a daily driver so reliability is a must. I have planned this engine out many times and keep changing my mind on various aspects. So now I'm back to the basics, but have this so far...

+10 or +20 overbore (I want the engine to last forever so no huge bores)
Moss SC kit
Burgess or Sean Brown SC Head
Cam - no idea at this point!
Pistons - also no idea
Fasteners - ARP
Radiator - 5-row
Ignition - Stock if possible, Lucas Sport Coil, NGK plugs (type?)

Thanks in advance for any input!

make ur compression ratio about between 8 and 7 to 1 so u can make boost but still have it drivable as a daily

I'm already planning to reduce compression from 8.9:1 down to the low 8's.

Steve, I'm no expert (have the moss s/c, but, everything else is stock), but, here's what I've gleaned. Make sure the bottom end is bullet proof. Some of your mods are going to overlap - i.e., the moss s/c gives such a power/torque boost b/c the old cast iron head didn't flow that well. If you flow the head and change the cam, you overlap what the s/c does, so it won't make as big a difference. With the cam, be careful that you don't go too hairy with long exhaust duration b/c you end up working at cross purposes with the blower. Rumor has it that Hans Pederson (hiflow.com) in Australia or N.Z. has developed a s/c cam (or at least the specs to get your own cut) for the B. Chris at Octarine Services in England might have some experience with s/c cams, and I think I recall a suggestion somewhere that John Twist (University Motors) or Carl Heideman (eclectic motorworks) - probably Carl - has worked on s/c and cams. They might be able to offer some advice. it seems like most people just go with the stock B cam b/c the uprated ones don't add enough to justify the cost - but, this is the non-s/c-specific ones.

The radiator - I'm currently running a little hot with the stock cooling system and electric puller fan, but, I think that is timing. I've got a rebuilt/early curved dizzy on the way which I hope solves the problem. The general consensus is that the later stock radiator is plenty and works even in hot climates. Mine runs hotter with the s/c (and as noted, I'm still working on things) but, even in 95+, high humidity, in stop and go, I didn't boil over.

Jeremy

Steve, the stock compression in fine, you don't have to change that.

I assume that you have a GB engine like me?

I found a really good article on this, I'll see if I can find it.

If you are trying to extract more than 125 at the wheels, it's easily done with minimal head work, a mild cam, and forged pistons, if you want to spend that kind of money, they're expensive.

The stock Moss SC doesn't create that much boost at all, unless you modify it with different pulleys or internals, you'll be fine with regular pistons and the regular 8.75:1 comp ratio.

The forged pistons are also key if you're gonna build a burner, but you can use the stock ones if you stay stock.

The kit as sold in the box was designed with a very low boost to work on an engine that was used and STOCK.

But, that's just a starting point. There's many, many roads to take from there.

Keep me in the loop with whatever you find. I'm currently doing this too.

I actually got a fender on yesterday. Lots of work to do on that. It doesn;t fit "perfectly" I'm glad I put it on before painting!!!!

Brian

I have never gotten a break down to know the price of forged pistons but if it were mine that would be a must. Do it once, do it right.

A blower and reliability? Thats a lot to ask from these old engines.Anyway ,don't use cast pistons or you may get holes in the domes.Have the crank counterweighted and use plastigage when fitting the bearings so you will know its a good fit.Get the strongest connecting rods. Use an oil cooler and change the oil often.If you drive hard and do good maintenance you may get half the life from your blown engine.If you drive easy most of the time ,you may get the same life as without the blower.

I've already looked into Hans' cam and I'm leaning that way. But I'm not set on it just yet. I do know a couple people running that cam so I am looking forward to their latest reports.

Forged pistons are almost a certainty. I will need new pistons anyway since I'm boring the block slightly. Since my compression is already above the standard high compression engine, I will be lowering it slightly. I won't know exactly which pistons I'm getting until I have the data on the head I will be using.

I have the basics covered, really, so I'm mainly looking for real-world experience with various mixtures of components.

What is your compression now?

On pump gas you can run on a standard HC stock engine with 8.75:1 pistons you can run almost 11 psi of boost. Thats 3-4 psi higher than the stock Moss SC that puts out between 7-8 psi at sea level. Which we're at thankfully. To get to 11 psi you would be going up 2 standard pulley steps to get there. Once you start getting over 11 psi then you're starting to get into the realm of race gas and good forged pistons.

At the standard psi, they're NOT essential. If you get them, they are definitely a bonus, and I agree that while you're spending this money, what's another $7-800 bucks, that's what they usually cost, sometimes a lot more!

I saw a set for an MGB that are Forged AE pistons from SC Parts in England and they are 658 brit pounds which is about $1300 US dollars. So they add a substantial amount. I do believe that they can be had for less from a US supplier.

If you feel that lowering your compression is necessary, then do it. But, from what I've researched since I got the Supercharger 3 years ago, it's not necessary.

The compression ratio and the amount of boost put out by the supercharger are proportional, I don't know the exact ratio, but it's something like for every 2 psi of boost at the SC it's equal to 1 or so as far as the compression ratio is concerned. In other words if you put a higher psi pulley on your SC that pumped out 9-10 psi, it would be similar to raising your compression ratio in the engine to 9.75:1 assuming that you have 8.75:1 pistons. And you can still run premium pump gas at that level, anything higher and you'll start to get some detonation.

Brian

My compression now is believed to be around 8.9:1 or 9.0:1 but it hasn't been accurately measured yet. I will NOT be running 11 PSI!!! Reliability is very important to me since I drive my MG to jobs that I cannot be late for most of the time. I think the standard pulley will be just fine. From reading the reports in the UK BBS' Supercharging Forum, many people have found that lower compression and more boost tend to equal more power than the opposite setup. I'm thinking that 7-8 PSI will be about all I can handle but there will certainly be some amount of experimentation at first. I do want to minimize the "fiddling" though. I'd rather drive than tune any day. :)