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hmmmmm. Kompressor RS.........

Just did the deal on a Rotrex S/30-74 supercharger.. aghhhhh

500 squids...

will have to try changing the power steering pump for an electric one to make room...

hmmmmmmmmmmm,,,......... me likes forced induction..............

Joe.... watch this space......
  172 Cup, V6 255, Williams


Are you doing this yourself?

I am currently building a project R1916v, and am thinking about blowing the F7P engine (same as clio 16v engine)


Hi Guys, yes, I will be doing this myself - time permitting -

The blower is from a volkswagon specialist, I was ringing around trying to get a g-lader compressor when I found a guy with the Rotrex, he had it on a 20v vw unit giving about 275 @ flywheel. Unit is 3 weeks use only - he changed to a giant turbo lol..

For £500 I managed to get the blower - which is tiny.. , the oil cooler (although it can be lubricated from the power steering circuit) and a couple of pipe lengths.

heres the plan so far..

where to mount it..

on a 172 there is hardly any spare sace at the alternator end of the unit, I would also require my A/C to be retained. the mounting at the mo in the 172 for anilliaries is - bottom to top - a/c unit, power steering pump then alternator.
I am hoping to move the power steering pump - either by using an electric pump from the cup series (bulkhead mount) or by driving the pump from the rear of the alternator (as per some vauxhall).

the alternator can be moved down, and then the blower mounted where the alternator sits now - similar size too.

one belt will be used to drive a/c, alternator and blower.

the front ali housing for the ancilliaries may need replacing with a custom unit .. that will be fun..

I am looking for about 7-9 psi boost, this should give about 250 at the flywheel.

a water to air heat exchanger (homemade) will cool the charge. Electric pump for the coolant to a front mounted rad - can be a lot smaller than an air to air intercooler too.

as for ecu mods etc.hmmmmmmmmmmm

well, the biggest problem with the 172 mk2 is that the fuel rail is a returnless system, the pump and regulator is in the tank. some of the bosch units (not sure what reno use yet) are electricaly adjustabe for pressure.. so thats a possibility, otherwise a seperate fuel pump and reg may have to be used..

alternatives are bigger injectors but will have to see how the ecu handles that.

as for map sensor etc, it may well be possible to apply pressurised air to the atmospheric port on the MAP sensor so it never sees boost, I am working on that now LOL...

no ignition mods planned at this stage as the boost will be relatively low.

money has not exhacnaged hands yet as I am awaiting confirmation of the exact model number - all flow maps are available on the rotrex site.

out of interest, I have also been offered a sprintex unit.. this is much bigger, but may actually mount more easily along the front of the engine

I am looking into this at the mo..

heres some shots of the sprintex unit.. the carbs and manifold are replaced with an elbow, the outlet is also changed to an elbow.

this unit, although larger, may well be able to use the existing power steering pump drive housing with the blower along the front of the engine, the electric fan would need moving though..



re fitting... the best plan so far is to replace the powersteering pump with the cup electric unit... then run a shaft from the ps pump mounting to the gearbox - air filter housing location.

this would allow the blower to be mounted where the existing airbox is.

the problem is going to be fabricating the shaft, tube and bearings assembly, however, my neighbour has an engineering company and we are looking into this as we speak.


Jeeeeeeeeezus Cap, I really wish I know what you were talking about, I really do, seriously ! Sounds like a very interesting project and if it comes off then the car should be mental !

What sort of performance difference do you expect in terms of time ? I understand that much !

MATE, i hope you pull this off.....lots of luck!!!

Man, and i thought i did a few silly things. if there is little space, in some cases wouldnt it be easier to fabricate a new front crossmember?

Hiya Ben,

thats a possibility, but I would like to keep the car as standard as poss in other areas.

the Drive arrangement should be fine, providing the thing is true with adequate bearings and lube.

it has other advantages too, eg - Pully changes will be easier, there is also the possibility of driving the original ps pump from the blower end.

Also, the original ps pully will be used at the alternator end of the shaft.. this will mean no changes to the existing belt drive assembly.

another area of interest is the non return fuel line of the 172rs Mk2.. it is possible to put an inline pump in the existing fuel feed and PWM the pump motor to act as a booster pump. It needs a pressure sensor in the induction to control the pwm pulses, but Maplin do one for 25 squid. the pwm controller can be a pic micro.

this means that the original injectors are used with the extra fueling being controlled by the booster pump in relation to the blower boost pressure.


i thought the injectors can handle another 20-25% flow. Didnt know there was no return line.

Are you just gonna run the injection system as standard? i.e just increase fuelling?

Hi Ben,

there are several possibilities.

first, increase the fuel pressure on boost only (using an inline pump much the same as a shower booster pump)

run a dedicated management system...

or, increase the fuel pressure by electronically controlling the pump regulator in the tank (If this is a bosch unit I have the details)

I think the first plan is to get the physical blower into the vehicle with a drive system, then, worry about fuelling etc.. I am confident the mechanics will be more complex than the electronics.

once the unit is actually working on low boost only... with pressure increases on boost only .. then the next stage would be to remove the engine, fit vel-satis low comp pistons - or forged units ... increase the boost and fit a full engine management system.

I am hoping the low boost would give about 180 @ the wheels, the higher boost is the land of the faires as noone as done it yet... thats when the fun starts with the clutch and box, although I am confident that the smooth deliver of power should be kind to the box - albeit the clutch will need upgrading..

stage 2 of the project, if stage one is succesful, should push over 200@ wheels.. depending on strength of the unit...


Stu, lol

if you want any of this explaining, just let me know.

there are quite a few guys on here that could help decode this too.


in a nutshell.... the engine is an air pump..

increase the pressure of the inlet air and you get a bigger bang (providing fuelling is correct). (More air fuel mixture in the cylinders per rev)

all the stuff re engine management is simply to achieve a way of controlling the mixture (fuel added to the increased air) and then later retarding the ignition so that the engine doesnt suffer detonation (pinking or pinging which can destroy all known germs and engines LOL)....


Well I learned alot today by reading all this, thnx for the explainations Joe.

Best of luck with it and I would like to see the follow up when ya complete it.
  CTR EK9 turbo

Woa, good! If you manage to get it to work on yours, would you mind doing the same to mine if i gave you a Marsbar?!

Hi Simon LOLOL...

just ONE marsbar... ??

What I can do is document the process so that if it turns out ok, there is a plan for others to follow.

I have no probs with that at all.


Hi Paul.

Thanks M8.. I would appreciate any input you guys can offer.

the goal is not only to supercharge it, but also to keep the unit (in the first stage of the project) as close to manufacturers spec as possible - ie, make no huge changes to the engine bay. it must be capable of being removed if necessary.


cant you skim the pistons to lower comp, or just enlarge the valve pockets?

Ive been studying engine management and its very time consuming. All the load sites, speed sites and maps etc. But its all very very interesting.

But i wouldnt worry about pinking, detonation (pre-ignition) is what i would worry about. Besides, with the knock sensor, itll be very hard to get the engine to pink.

Plugs are gona be important if cylinder temps rise and you get detonation....but if that happens, youll know about it.......we wont have an engine after that will we!

DOH, i just rambled on and on and noticed you mentioned detonation already!!!

Go with the rotrex mate, its miles smaller!!

And if you gonna run a full EMS, than i highly recommend Emeralds M3D system. Can run anything from TBs to SC & Turbos....And its dead simple.

Anyway, back to the plumbing, are you planning to connect straight to the throttle body? Theres not uch else you can do within reason is there?

Maybe a centrifugal clutch system on the charger means low down bhp aint robbed by the charger and so itll kick in at say 2000-2500-3000rpm depending on the stength of the springs? Bit filldy though, maybe a kart clutch?

nice comp!
i got into overworking processors, but my heat sink designs never worked, even when water cooled and placing the heat exchanger next to my aircon....i went through 3 processors.....then gave up.

p.s. what about megane pistons?
  CTR EK9 turbo

Hahaha, oh dear, cool! Ok, ill stretch to a "big one" marsbar...Thatd be cool if a company took on your design and developed the supercharger. Maybe Hillpower could fit them to our 172s?

Hi Ben.

skimming the pistons or pocketing can often decrease the valuable amount of strength in this critical area, it would be fairly easy to use Reno Vel Satis pistons me thinks.. forged ones may be a good investment..

Engine management is one of my hobbies.. we have a ford eec-iv unit here with a home made flashram adapter on the J3 port, it is capable of being programmed fully, however, yes, the emerald, dta or luminition are good candidates. It is often the case that you loose the ability to have the knock sensor in circuit though with the addon units.

Plumbing, Nick Hill recommended running the throttle body from the existing plenum on the intake to the supercharger.. I hadnt considered this, but it makes sense.. otherwise the pressur build up in the system at throttle plate closure would necessitate a dump valve or bypass circuit. so thats the route I will take. The Mk2 is great as it has the fry by wire throttle, so no cable to hook up, the stepper drive for the throttle plate is already on the detachabe body part too ...

the rotrex (Yep, I did decide on it) consumes little power as compared to the sprintex so I hopefully wont need it, the boost is instantaneous too, but is obviously fully proportional to engine speed only.. if I went the route of a clutch, it may be a possibility to use an aircon electronic clutch and controll it from an rpm sensor... but, as said, I dont think it will be necessary.

plugs, yes, they will need to be considered absolutely..

I am unlikely to need intercooling in stage 1, but will probably add it to prepare for stage 2 (Low comp high boost ignition r****d etc) the intercooling of the charge air will help maintain a lower cylinder temp too.


ok, let me get this straight. Your putting on a supercharger to run at 7-9psi, with standard compression and not altering the fueling.?

I hope youve saved for a new set of pistons, your going to end up with a hole on one or all of them.

It not going to last very long if you just bolt on and go. You also have to look at getting the timing altered as a forced induction engine needs to fire earlier to get a better burn or you will just end up blowing out the spark.
The ECU wont know what to do when it starts getting air forced into the engine.

You can get an electric power stearing pump of the 1.9 Diesel Clio, I was going to use one as I replced the mechanical one with an air con pump, but decided not to have air con in the end.

Hi Barry, no Sir, I am NOT

the fueling mechanism will be either an inline booster pump with electronic controller or an engine management system. (I did state this above)

at such low boost levels there should be no real problems.. the on board ecu detonation (knock sensor) will take care of ignition (to a point), but for higher boosts, then yes, low comp pistons and boost r****d are mandatory.

Hope that helps..


Barry, also regarding the comment the ecu wont know what its doing

yes it can be made to do so.. the biggest issue is the map sensor - as it cannot see boost.
what needs doing is to apply boost pressure to the atmospheric (open to air_ port on the map sensor. the atmospheirc reading or reference is now= to actual atmos pressure + boost, the DIFFERENCE that the map sensors measures is now back to normal - ie - it doesnt see boost.

so, providing the fueling can be compensated for, the mixture is back to normal.. ie - preplanned internal Stoichiometric table. - (And chemical ratio is established.



WDK, so it looks as if your sorted. Im just learning the mapping and theory right now as im really a carb person (had to adjust blind during races on my 250cc cart!!!)

But if you can get your head round it all (the myth that its terribly difficult) the it makes so much more sense than DCOEs!!! supposing your useing decent TBs though.

Again, Good luck and keep us posted!!!

cheers mate, butim still working through several books, ill probably get back to you on it though.

anytime Sir.

ps, hows the head business going ??.. and did ya get the flow bench sorted ??

I have an idea for a homemade flow meter if u r interested..

Just use a high volume pump - pressure dont need to be too high (aquarium air pumps are great (not the tank ones LOL, the rotary ones to supply 100 tanks at one - about 300 squids...)

a gauge on the input, and another on the output... electronic if poss.. feed it to an op amp differentiator to read the drop. I think I mentioned before, one of my pals from long ago was flowing a 16v vx head, he had to eventually add ali weld to the inlet ports and grind to INCREASE flow...

  BMW 320d Sport

Hmmm...interesting. Itll be good to see how you get on Joe. Lets hope the engine management can supply enough fuel.

Im meddling with a boost r****d unit at the moment to r****d the ignition when Im on gas, Ill see how it performs. Pretty easy to hook up though. Actually you can help me out here (Joe or Ben)...

Ive wired it through a relay so that when the nitrous system is armed *and* firing, the ignition will r****d by between 4 - 8 degrees. However the last bit of wiring is hooking up the r****d unit to the actual coil and all it says on the instructions are to connect it to the + and - of the coil. Now the problem is Ive got an ignition module - a coil and amplifier and there are a couple of multiplugs that connect to it.

So the question is do I leave the multiplugs alone and connect directly to the terminals on the coil or do I cut into the multiplug lines? Ive looked at the wiring diagram in the Haynes and cant fathom it out. Normally the diagrams are no problem but Im really scratching my head over this one!

Downloaded that pdf captain. Im going to see if I understand this malarky Hey some of my electronics degree might come in handy now hehe.


Hi Nick,
hmmmmmm. I presume the following as I am not familiar with your setup.

the module, amp n coil need to be operated as a set, the coil is probably a high discharge unit fed from the amp, the module may well taylor the signal..

the boost r****d would be a simple sample and hold circuit to delay the pulse.. wait a slight amount of time if you know the rpm.. then u can calculate the delay or r****d amount of the ignition pulse to fire the plug.. yep ??

so, if that is the case, one would presume that the trigger to the module needs to be fed to the r****d unit.. (In effect disconecting it from the module).. the conditioned - or retarded output from the r****d unit is then fed to the input of the module (for module read ignition module)

However, the module may well be a decode from the CAS (Crank angle sensor).. if this is the case, then the feed from the module should go to the r****d unit, and the output of the r****d unit should go to the amp...

Jeeeeez, that sounds clear as mud LOL...

nope, I read it again,, it sounds about right LOL... dont just connect to the coil is the main thing.


and Chun.. have fun dooooood, its great stuff.. opens up a whole new world of tuning possibilites...

Ive always been insterested in how mapping was done. Should understand at least some of it Anyone got a pdf on how the renault Ecu is connected to the port inside the car?.


ok, ive never heard of this ecu before so please explain a little.......its late here and i cant be bothered to read i now.

1: a ford ecu
2: ability to control an entire engine from fuelling to ignition.
3: can it handle forced indution?
4: most famous use (i.e modle of car)
5:anything else it difficult to program? do you make your own software?

CHeers Mate