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I have read with interest several threads about supercharging as it's something I want to do to my 4.6 110 but I don't know much about superchargers.

Quite a few of the local "petrol heads" are driving modified Jap saloons with insanely huge turbos, even though these all seem to have variable boost they all have waste gates.

My L322 is supercharged but it certainly doesn't have anything like a waste gate so what is governing the air pressure?

Is it just a case of selecting the correct supercharger pulley size so it can't exceed the desired boost pressure at maximum RPM?

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That's exactly how it's done, vary the size of the pulley to limit boost.

The dump valves are only put in place to prevent damage to the throttle assembly if the supercharger is fitted upstream.

If you rearrange the inlet system so the throttle is fitted before the supercharger this isn't required.

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This was prior to the finished result in my set up.

I used an adapted Ford Lightning inlet jointed to a Range Rover throttle body, it gave me the perfect throttle sensor, size and shape for my snorkel arrangement, my kickdown / accelerator cable was kept simple and standard'ish, removed the need for a dump valve and finally kept it simple for stupid.

Big bonus - sounds awesome.....

post-1382-0-03889100-1426405768_thumb.jpg

post-1382-0-91775500-1426405853_thumb.jpg

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Well noted Mr Conway, buts that is the normal way that I see it, and why are you up so early????

Sorry folks for some reason - probably because I'm dim, I have manage to post the same'ish photo upside down twice.

Also for the more astute amongst you may notice that the belt is bypassing the charger pulley, this was because the coupling adaptor was rattling its head off and I used it to do a competition the next day, so decided to do it with charger in place but just revolving itself in the airstream. I was just trying to show the rear throttle body was that I have used.

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It is still recommended to use a bypass valve to provide some cruise efficiency (fuel + cost) savings when you don't need the boost.

A bypass valve is not the same as a dump valve, it is basically a butterfly valve run in parallel across the supercharger, and has a pneumatic vacuum actuator on it, so that when the engine is cruising, and there is vacuum behind the throttle valve, the vacuum developed partially opens the bypass butterfly valve and reduces the boos pressure across the supercharger. As you open the throttle, the vaccume reduces and the bypass butterfly valve closes and the supercharger boost pressure increases.

I don't know how much you know about superchargers, and I've probably listed this before, but there is an old spreadsheet that was developed by Sprintex Australia that had a whole load of manufacturers at the time (early 2000's ) listed with alternative superchargers that allowed you to play around with the figures a bit, note it's not 100% correct as there is no density correction (as when you compress air it increases it's temperature so becomes less dense), and there is no allowance for supercharger efficiency / rotor efficiency but it will give you a start on supercharger selection (note if you get the new version of the sprintex site, they wisely got rid of their competitors products.... given everyone was just selecting other products with it).

http://tomasz.data2net.org/Blower_Calculator.xls

The thing that governs / limits supercharger selection is a combination of maximum intended engine RPM not exceeding the superchargers boost at it's rated maximum RPM.

Edit (try to add a bit more info when I get the chance [life, kids, wife etc]):

There are 3 basic designs / types of supercharger:

Lysholm, (twin screw) positive displacement supercharger, it is the most efficient (i.e has the least leakage, plus lowest temperature gain) the list of manufacturers include: sprintex, whipple, and opcon as far as I am aware (Magnacharger is another one, although I thought that they were whipple SC's rebadged..... happy to be corrected) not EATON! (I'll come to that later on below). These are the least common design as the rotors are very complex to machine, the original Sprintex (made by DPR of Yeovil [Dennis Prindle Racing of drag fame]) used an older rotor pattern that may have been one the edge of copyright. Anyone producing a lysholm supercharger needs to pay a licencing fee to the patent holder I believe, hence the cost premium plus to some extent. I found a piece of software that was developed by a university a while ago (cambridge may have been) that would design the rotors for you to your parameters and was very interesting especially as it could do 5-lobe design.

Then there is the traditional dragster + run of the mill (most common) type which is the Roots blower, think "fan" running at high speed, with close tolerances to the walls to limit leakage.... list of manufacturers include roots, eaton, and quite a few others.

Then there is the centrifugal supercharger, think turbocharger but belt driven at high speed, manufacturers include procharger and paxton as well as a few others.

For me lysholm design every time.

Note: there is a "newer" design of the eaton (roots type) called the TVS, which is still a roots type and despite first looks that it's a positive displacement type (lysholm) it's actually got twisted rotors by quite a high degree of twist, these are interesting as they have improved the efficiency of the simple roots design by quite a bit and are now found on most run of the mill newer cars with a factory fitted supercharger .... including the L322, and LS engined corvette (LS9), ford mustang etc and a lot of other engines. the efficiency is very close to the lysholm and for the most part probably not a lot in it plus it's available in a good range of sizes

If somebody wants them I'll transpose all of the formulas for supercharging and some for turbocharging (note I've still not got my head 100% around turbocharging formulas, around the area of exhaust gas expansion and A/R's and how the two relate or at least by gas velocity)

supercharging is a little less complex by way of calculation, where as turbocharging has a bit which is a black art around A/R selection. [i'd like to maybe in the future use forced induction on the LS hence everything I do has a future proofing concept for space allocation and configuration although it's likely to be turbocharging using twin GT3582's, coupled to gear selected to protect the drivetrane) [there is a "bad boys mustang" that uses this concept and I doubt it's the first]

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Great information, I just looked at the Vortech site, they make centrifugal superchargers but are also a lysholm agent as well.

Thier site has further information, some compelling anti roots type verses centrifugal info but as a lysholm agent they don't compare thier two types against each other.

Although centrfugal is much more effective you can't beat the look af a twin screw blower on top of a V8!!!

Marc

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It is still recommended to use a bypass valve to provide some cruise efficiency (fuel + cost) savings when you don't need the boost.

A bypass valve is not the same as a dump valve, it is basically a butterfly valve run in parallel across the supercharger, and has a pneumatic vacuum actuator on it, so that when the engine is cruising, and there is vacuum behind the throttle valve, the vacuum developed partially opens the bypass butterfly valve and reduces the boos pressure across the supercharger. As you open the throttle, the vaccume reduces and the bypass butterfly valve closes and the supercharger boost pressure increases.

I don't know how much you know about superchargers, and I've probably listed this before, but there is an old spreadsheet that was developed by Sprintex Australia that had a whole load of manufacturers at the time (early 2000's ) listed with alternative superchargers that allowed you to play around with the figures a bit, note it's not 100% correct as there is no density correction (as when you compress air it increases it's temperature so becomes less dense), and there is no allowance for supercharger efficiency / rotor efficiency but it will give you a start on supercharger selection (note if you get the new version of the sprintex site, they wisely got rid of their competitors products.... given everyone was just selecting other products with it).

http://tomasz.data2net.org/Blower_Calculator.xls

The thing that governs / limits supercharger selection is a combination of maximum intended engine RPM not exceeding the superchargers boost at it's rated maximum RPM.

Edit (try to add a bit more info when I get the chance [life, kids, wife etc]):

There are 3 basic designs / types of supercharger:

Lysholm, (twin screw) positive displacement supercharger, it is the most efficient (i.e has the least leakage, plus lowest temperature gain) the list of manufacturers include: sprintex, whipple, and opcon as far as I am aware (Magnacharger is another one, although I thought that they were whipple SC's rebadged..... happy to be corrected) not EATON! (I'll come to that later on below). These are the least common design as the rotors are very complex to machine, the original Sprintex (made by DPR of Yeovil [Dennis Prindle Racing of drag fame]) used an older rotor pattern that may have been one the edge of copyright. Anyone producing a lysholm supercharger needs to pay a licencing fee to the patent holder I believe, hence the cost premium plus to some extent. I found a piece of software that was developed by a university a while ago (cambridge may have been) that would design the rotors for you to your parameters and was very interesting especially as it could do 5-lobe design.

Then there is the traditional dragster + run of the mill (most common) type which is the Roots blower, think "fan" running at high speed, with close tolerances to the walls to limit leakage.... list of manufacturers include roots, eaton, and quite a few others.

Then there is the centrifugal supercharger, think turbocharger but belt driven at high speed, manufacturers include procharger and paxton as well as a few others.

For me lysholm design every time.

Note: there is a "newer" design of the eaton (roots type) called the TVS, which is still a roots type and despite first looks that it's a positive displacement type (lysholm) it's actually got twisted rotors by quite a high degree of twist, these are interesting as they have improved the efficiency of the simple roots design by quite a bit and are now found on most run of the mill newer cars with a factory fitted supercharger .... including the L322, and LS engined corvette (LS9), ford mustang etc and a lot of other engines. the efficiency is very close to the lysholm and for the most part probably not a lot in it plus it's available in a good range of sizes

If somebody wants them I'll transpose all of the formulas for supercharging and some for turbocharging (note I've still not got my head 100% around turbocharging formulas, around the area of exhaust gas expansion and A/R's and how the two relate or at least by gas velocity)

supercharging is a little less complex by way of calculation, where as turbocharging has a bit which is a black art around A/R selection. [i'd like to maybe in the future use forced induction on the LS hence everything I do has a future proofing concept for space allocation and configuration although it's likely to be turbocharging using twin GT3582's, coupled to gear selected to protect the drivetrane) [there is a "bad boys mustang" that uses this concept and I doubt it's the first]

I would have said a better description of the Roots type would be a big oil pump with only 3 or so teeth on the gears, also positive displacement and tend to heat the air a lot. Now days turbos are probably the cheapest option and if sized correctly I doubt they would have any disadvantage to the supercharger at all

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Except the huge heat source under the bonnet which is why US cars sometimes has the turbo under the rear bumper!

And the on off switch effect, great in reduced speed limits, reach the right revs and all of a sudden you are breaking the law and rushing towards something in front of you! As you can tell I hate turbos?

Supercharger alwas for me.

Marc.

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Except the huge heat source under the bonnet which is why US cars sometimes has the turbo under the rear bumper!

And the on off switch effect, great in reduced speed limits, reach the right revs and all of a sudden you are breaking the law and rushing towards something in front of you! As you can tell I hate turbos?

Supercharger alwas for me.

Marc.

Ive never seen an OEM install under the rear bumper, I have seen a kit like you describe but that was just a cheap nasty way of fitting a turbo to a car that never had one. If sized correctly it is no more of an on off switch than anything with a VTEC type cam setup (unless you are talking about something making big horsepower which is kind of irrelevant anyway).

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I purchased it from a v8 tuning company who had 10 of these kits, new old stock about four years ago.

It was originally fitted to the De-stroked rover v8 powered TVR's which were 2.0L for the Italian market.

They utilised an Eaton M90 supercharger (suits up to 5.7L engines) and had it underdriven as it flowed enough air for the 2.0Lversion.

This kit is essentially the same as what I had intended to fit on my 4.2 v8 in my 110 but you can see it has a bypass valve between the supercharger and throttle body, my kit didn't have this modification.

post-47238-0-31911900-1426461463_thumb.jpgpost-47238-0-55709400-1426461474_thumb.jpgpost-47238-0-67519300-1426461486_thumb.jpg

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Thanks for the pictures.

Care to mention the "V8 tuning company"?

PM me if you prefer.

Did you actually run the supercharger?

By the way I think I've heard your 110 (I work in Disley) I'm not a Diesel fan but it sounds awesome!

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Possibly RPI or V8Developments, it was an eBay listing years ago and I took the last kit...

Unfortunately I never got the chance to run it, I bought it when I was a 19 thinking 300Bhp+ would be nice. My insurance company had quite the opposite thought, so I shelved it.

Although a year later they changed their minds and I fit a cosworth T34 turbo instead.

post-47238-0-01200900-1426462970_thumb.jpg

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And the on off switch effect, great in reduced speed limits, reach the right revs and all of a sudden you are breaking the law and rushing towards something in front of you! As you can tell I hate turbos?

Maybe in the 80's it was like that, or if you are chasing huge power with a small engine, but a modern well setup turbo has very little lag and will start making positive boost at a very low rev range. The old setup I had on my MX5 was a diddy little garret turbo - it started making positive boost at about 1200 RPM which would increase linearly as the revs came up. Driving it it was very much like a car with a larger engine, or just like a supercharged one but without the whine...

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That may also be the improvements in ball bearings against journal bearings

BMW m3 does have two turbos of different sizes so one will spool up at lower rpm and the second at higher rpm but that does not work so well with a v8 application unless you're going to attempt a quad turbo installation

Plus you still need to consider at what rpm do you REALLY need the turbo in your application

Turbo for low boost applications (1.6 or so pressure ratio) seems to be a black art, especially if you're looking for just a bit of a performance improvement (say up to 50% over stock) not looking or wanting major engine rework

Diesel another animal as the engines seem more robust than a na petrol built for emissions control targets (high compression ratio plus high operating thermostat)

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Possibly RPI or V8Developments, it was an eBay listing years ago and I took the last kit...

Unfortunately I never got the chance to run it, I bought it when I was a 19 thinking 300Bhp+ would be nice. My insurance company had quite the opposite thought, so I shelved it.

Although a year later they changed their minds and I fit a cosworth T34 turbo instead.

attachicon.gifimage.jpg

Ash, you're giving me expensive ideas :ph34r:

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I thought RPI were against supercharger installations, and use to have several pages on their website attesting to it given that the outer cylinders tended to end up running leaner than desired (from memory that was their reasoning / thoughts)

http://www.v8engines.com/engine-3.htm

http://www.v8engines.com/projects-020.htm

Eaton M90 anyway.

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