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TR6 TR6 Supercharger

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I

ichthos

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I find myself hopelessly addicted to my car. There is always something I can do to make it run or look better. Just when I think I am happy with the performance of my TR6, I recieve my magazine from Moss with an enticing article on how to put in a supercharger. I had wanted to keep my car stock, but ..... Moss states that their supercharger can increase the horsepower from around 75-80 to around 119 horsepower. Of course this is not cheap, costing around $3,500. Can someone explain to me what a supercharger does to increase horse power? What are the implications of supercharging a TR6? Does the gas mileage decrease? With the increased horsepower, does this mean that I would need a different rear end? What are the drawbacks to installing this kit?
Thanks, Kevin
 
Very good question Kevin. I always wondered that myself. Hopefully someone will answer it in layman terms so I can really understand. /ubbthreads/images/graemlins/cheers.gif
 
In layman’s terms:

It's like a funnel and a hose at a frat house. /ubbthreads/images/graemlins/thirsty.gif /ubbthreads/images/graemlins/thirsty.gif /ubbthreads/images/graemlins/pukeface.gif It crams extra fuel and air into your engine. /ubbthreads/images/graemlins/hammer.gif /ubbthreads/images/graemlins/hammer.gif

It’s literally a blower, a fan that increases the flow of air that can accommodate extra fuel. The increased pressure and extra fuel create a bigger bang.

There are different opinions about wear and tear on your engine, etc. Your engine should be in very good condition before considering this.

There was a vintage supercharger for 4-cylinder British cars made by Judson: https://www.infostuff.com/carstuff/mgacbc/mgajudson.htm

You could get a lot of performance work done to your engine for $3,500. /ubbthreads/images/graemlins/yesnod.gif
 
Curious about this myself - anyone know if compression ratio is a big factor here? I was thinking the later model TR6s might be better candidates with the lower initial compression ratio, but I'm just guessing.

Randy
 
Kevin,
A supercharger is basically a compressor. Instead of your motor’s piston going down and sucking in air, a supercharger sucks in the fuel and air, compresses it, and then shoves it into the combustion chamber. This gives you more fuel and air, which gives you a bigger bang. Mileage will decrease if you put your foot into it. By adding all this horsepower, something might give. To do it properly, the motor should be built for the supercharger. I don’t know how strong the rods, crank and pistons are on these motors so I would prefer a motor with a forged crank and forged pistons. Also, good quality rods and bolts. A supercharged motor should also have a lower compression for the extra fuel and air.
That’s the basics.

Bill
 
Dang, Kev, slow down boy! Last week you were getting your lights to work. You've done a lot of reading in a week. Joking aside, beware the supercharger. It is a money pit.


Bill
 
Yipes, that increase would be between 30 to near 40% increase in rear wheel power with out openening the motor! When you consider costs of labor and parts, you may not find anything that can compete.
 
Nitrous is considerably cheaper to purchase, though the long term destruction will cost just as much.
 
[ QUOTE ]
the long term destruction will cost just as much.


[/ QUOTE ]If not more! /ubbthreads/images/graemlins/nopity.gif
 
Our long stroke engines weren't really designed for superchargers, turbochargers and the like. When you introduce something like that, you are going to use it, probably a lot. The added stress on the moving parts is very high and more sudden. A cam is high but more gradual.
I watched a TR6 with nitrous at some drag races. When the driver flipped the switch, the performance was incredible. So were the noises and the smoke when he backed off. I figured each trip to be his last. Personally, I want dependability more than I want a grenade.
 
I agree with the guys that are saying get ready for things to start breaking if that is all you do.

I am not saying not to do it but you will either rebuild everything else before, when they are in one piece, or later, after they are broken.

I can tell you this, things break in progression, weakest first.

You might ask yourself this question. If you were to go out now and wind up your engine and then release the clutch would you worry about breaking things, how about twice, or three times? How would you feel if you addd 50 HP?

The extra power would be fun though! /ubbthreads/images/graemlins/yesnod.gif
 
Thanks for all the replies. And yes, Bill, I probably need to slow down. My wife has been very patient with me, but if she even knew I was considering this, she would blow a fuse.
I have a long ways to go in TR6 education, but I feel as though I could fill a book with the knowledge I have gained from the forum over the last year. I think it is kind of funny that I am considered a "senior member" when it looks like the qulifications for such a title come from the amount of posts I have put up in getting help with my car. Thanks again all. Now for my next post....
 
Hi Kevin,
This thread comes up every so often when the performance bug bites. After running a blower for 6 years I pretty much have discovered the advantages & pitfalls. The SC most commonly used for this car is an Eaton M62 https://www.automotive.eaton.com/product/engine_controls/superchargers/M62.asp
It is a roots style with some advancements in rotor design. It uses two mating rotors that drawer air in , compress it & force it out. The system used with a carburetor is described as a "wet" system since it drawers fuel & air through the blower. More current fuel injected technology has the fuel entering the flow after the blower & being regulated by engine management controls (computer). The beauty of the newer technology is the incorporation of a by-pass valve. What this does is open & close a circulation port that either allows boost or opens for normal driving. You can drive around all day & never see boost. It is truly "power on demand". It is vacuum operated & when vacuum drops in the intake manifold the servo closes the port allowing pressure to build.

There are as many positive as negitive misconceptions of performance and durability gains. The most common is that your engine will blow up & parts will start flying through the block. If you motor is within spec , your compression is under 8.5:1, you can tune your car properly and you follow the rules of any performance enhancement, you will have a very reliable motor with exceptional gains in performance. Is it perfect, almost. I would match idle & start-up ease with any stock TR & I know for sure that the street characteristics of my motor are far more tame than a motor of egual HP done the traditional way, carbs, compression and cam. There will always be something cool about lots of carbs that will never go away but if it's dollar for dollar performance , the blower is the best bang for the buck.

As with any power adder you should considor ignition, exhaust and driveline upgrades. I have abused the car using the stock trany & diff but eventally gave in to the Nissan differential & Toyota trany. These are defintly better units capable of handling the power.

The down side, more speeding tickets, the uncontrolable urge to constanly feel the acceleration & spending much more money on fuel. When your foot is in it you can see the needle go down
/ubbthreads/images/graemlins/cool.gif.
 
Doug:
I agree, the Triumph tractor thing comes back to mind when I think of design and Triumph motors. The long stroke is a problem if over pressurized, as is the short stroke. Generally longevity is reduced when potential power is increased and utilized. I really don’t know how ill suited the supercharger is to a long stroke motor vs nitrous or turbo’s. They all will blow up a motor if over utilized and they will all take a toll on the longevity of the motor. Will the longevity decrease be proportional to power use in all three alternatives?
 
A 30 to 40 percent increase in power puts the TR6 back to where it was designed with the PI system and the pressure that these kits generate is in the 5-7 psi range so even an early high compression US TR6 at 8.5:1 would not be in any danger compression wise.

There have been a few TR6 supercharger kits floating around for about 5 years now. With mostly positive results. A supercharger builds boost linearly with RPM. So the higher the RPM the higher the boost. Turbochargers can build boost much faster. Early turbo technology was famous for massive boost that was very hard on equipment. Modern turbo technology is much easier on equipment until you start building ridiculous amounts of boost as in more than 20psi.

The biggest advantage of mild supercharging (like the Moss kit) is that at lower rpm there is very little difference in performance over a stock TR6. So for mundane motoring, putting along though traffic etc... driveability and gas mileage are pretty much inline with a standard car. But as you dip into the throttle you tap into the power.

The kit in question is a long way away from a Top Fuel Drag Racing supercharger. The stock engine internals are more than adequate for the increase in power provided with this kit. As long as the engine is in good shape. Remember that increasing the power, in any way, will show you where your engine is weak.

With camshafts, most forced induction tuners find that stock cam profiles work better than radical cams (we are talking about street cars and driveablility here).

In regards to gas mileage. Anything that increases power will reduce mileage since it takes more fuel to make more power. Something about no free lunchs. However, when driven sensibly, a TR6 with this kit should see close to stock mileage. But why would you want to drive it sensibly? /ubbthreads/images/graemlins/jester.gif

Forced induction systems are displacement equalizers. Which is why in competiton circles, naturally aspirated engines are allowed to be quite a bit bigger than forced induction engines in the same class. The difference between a forced induction engine and a 'built' naturally aspirated engine creating the same power can be quite a bit. They are two totally different acting engines. A mild supercharger can turn your TR6 into a 'sleeper'. It will start and idle like stock and seem like a normal TR6. The supercharger 'whine' is minimal and when you put your foot down it will basically act like a normal car with a bigger engine. With a 'built' engine. Everyone around you knows its not stock even when it's idiling. Which is why I keep getting challenged by kids in Camaros. /ubbthreads/images/graemlins/grin.gif

There are a few BCFers that have either turbocharged or supercharged TR6's or are in the process of building them. It will be interesting to hear their input.

/ubbthreads/images/graemlins/cheers.gif
 
Hi Swift,
A slight correction, I think you reversed your thoughts.

"A supercharger builds boost linearly with RPM. So the higher the RPM the higher the boost. Turbochargers can build boost much faster. "

Its the other way around. You are correct that SC HP/Torque build in a liniar progression. But this means that the power is prety much the same as rpm's increase. SC'rs boost remains pretty much the same through out the rpm range and generaly build no more than 10lbs for street use. A turbo starts low and builds boost as rpm's increase.This means lower rpm performance suffered. Later turbo technologhy has all but eliminated turbo lag. Since turbo's are exhaust driven ,they speed up as the rpm's increase. A SC is belt driven but has enough rotating speed to produce it's maximum boost just off idle. It sounds like the SC should pump more as the pully spins faster but it's design max's out it's flow capability at a certain rpm and remains constant.

Some race track (drag strip) configuations use a SC for low end performance coupled to a turbo to take over for higher boost pressure at the upper rpm range.
 
As far as the long stroke. The biggest limiter is RPM. It takes a lot to make these engines (TR6) capable of spending time above 6000rpm. Stock TR6's make peak power below 5000rpm. Turbocharging or supercharging these engines are fine as long as you still shoot for the standard rpm range and not try to turn them into a turbo/supercharged 8000rpm monster. The longer stroke just moves the power into the lower rpm range. Those torque monster Cummins turbo diesels, like most diesels, are long stroke motors and they do VERY well with turbocharging.

/ubbthreads/images/graemlins/cheers.gif
 
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