neil-h

Don't get me wrong, it's a very interesting project. Always like reading proper DIY projects like this one and supercharging is definitely a left field option.

Just think superchargers sound funny

BlownImpreza

Hi everyone!

Not so many updates this week...I definitely didn't buy a front mount intercooler kit thats turning up on Thursday

neil-h: Yes, the Supercharger whine is definitely an acquired taste, but actually after a while you do get used to it

Hopefully I am going to get in the garage this weekend to get the intercooler (that I didn't order!) fitted!

Thanks!

mikeblackett

hi, im new to the site but have good knowledge of supercharging the subaru impreza, I came across your story and Ive noticed some fundamental flaws in your set up and I want to help you see this project succeed.

firstly you must do the calculations for the eaton 45 regarding cfm outputs from an eaton map, pulley sizes on both supercharger and engine crank pulley size are also required for the calcs.

secondly there is only one way to install a supercharger on any car the tb must be on the inlet side of s/c to control air flow there must also be a control bypass valve fitted in the system before the inlet manifold and you must be aware of parasitic loss of boost running an intercooler which should be taken into account when doing your calculations

As it stands just now you are heading for serious problems and it wont correctly work not to mention time and money wasted.

Il be honest with you getting the supercharger in and lined up is the hardest bit which you have done.

regards mike

BlownImpreza

Hello Mike and welcome,

Thanks for your input, I'd be interested in seeing some of the Impreza Supercharger projects you've completed and/or been involved in.

In response to your post, I guess I have a few comments/questions.

1) Regarding the cfm outputs, I did already mention the following:

"gazney101 - I don't have any data on the Supercharger regarding what sort of volume it moves etc, I will do some rough calculations at some point as I suspect a pulley change will be due further down the road. However, I was hoping to come up with something to control max boost that would mean not having to change pulley's...I have an idea in my head but am working out the kinks!"

So its not that I'm not going to/cant be bothered etc. I do now have some rough calcs regarding cfm.

2) The throttle body - to be honest I surprised its taken to page 3 before its mention. I have read countless posts/articles/technical sheets about the pros and cons of placing the throttle body before or after the charger.

I'd like to think i have a good understanding on the reasons for placing it before the charger. However, as my car does not have any pre-throttle body sensors I felt no reason to relocate it, I have spoken to and read about many a success story where the throttle body has been left after the Supercharger.

This does of course bring up the issue of excess boost, potentially flowing in the opposite direction, or forcing its way past a closed throttle butterfly and damaging it. There are some things that go without saying and one of them is a BPV. I will be fitting one, I've not decided on weather its a standard one adapted for my application (The Mini Cooper-S one is looking promising) or whether it'll be something I create from scratch etc.

Regarding the intercooler yes, I understand there will be losses - I have charged NA cars before so am aware about such things.

What I will say is that a lot of context gets lost in plain text and it ends up all coming across as arrogant - I don't want you to feel I have ignored your helpful advice and that I am blinded by "I know best" syndrome.

This project was deliberated on countless times before I even bought the car, and I have read and read into the wee hours of the morning to the point I'm confident about where I am going with it.

But as always help and constructive input is always welcome

Obviously if I stop posting it means everything I thought was wrong and I have a pile of broken bits where I once had an engine!

"Always look on the bright side of life...do do, do do do do do do!"

Thanks all

trails

iTrader: (41)

Nice reply

mikeblackett

hi,
I did not mean to offend you in any way with regards to the project just trying to offer advise.
As I was saying the only way to correctly control the air flow is to put the tb on the inlet side of s/c it doesn't matter whether if tb has sensors or not you must be able to control air flow pre supercharger and this will solve your concern with air forcing against the closed butterfly valve during idle or cruise conditions as the cbv will open under these conditions to eliminate this.
I know that the eaton m45 is off a cooper s which I do believe is 1600 cc and you are now fitting this to a 2000cc therefore it goes without saying the with the current s/c pulley it will not be able to displace the required cfm you envisage to require boost
I know you could install a smaller a pulley to increase displacement but there is a limit to how small you can go as the delta would increase due to the s/c having to work much harder and more stress on s/c resulting on s/c failure at the very least.
I have seen various supercharged project you say they have varying degrees of success this is due to mainly tb location and calc oversights for pulleys.
I would rather hear from you a complete success with your build than a failed engine and dream.

I did months of research, weeks of build time and still to calculate the build cost. it is a bugeye project and ive just to get the last of the build on the computer but its already to be booked in for the ecu and remap. il hopefully get it on the computer for you to see by end of the week.

regards mike

tubbytommy

iTrader: (20)

very intereresting thread for a change.
cant wait to see if it actually works

BlownImpreza

Thanks for the replies everyone.

Mike, you have not caused any offence - hence what I said about context being lost in text. Plus I did say in my first response that help and constructive input is always welcome.

Equally not wanting to cause offence, but I'm struggling to piece together your response - I'm not sure if you wrote it in a hurry but it seems to have a few mixed words/missing punctuations, so could you clarify the following?

"I know that the eaton m45 is off a cooper s which I do believe is 1600 cc and you are now fitting this to a 2000cc therefore it goes without saying the with the current s/c pulley it will not be able to displace the required cfm you envisage to require boost"

Are you saying that you think the Supercharger fitted to the Impreza's 2.0L engine will not produce sufficient cfm for any type of boost? You are correct that the M45 is fitted to the Mini Cooper S, however Eaton did not manufacture it exclusively for BMW/Mini. This is probably all things you know, so again to reiterate - no offence/cockyness/arrogance is meant.

The M45 model I have is in fact from a Mercedes C200K 2.0L - therefore will be favourably "pulley'd"for a 2.0L engine already. As mentioned previously, I have some calculations.

It would be nice to see some info/images on your current build when you have had it mapped. What Supercharger are you using?

Thanks again.

mikeblackett

Hi.
sorry I was in a rush when I posted last reply.
Your absolutely correct regarding the application of the m45 but it depends on which generation of m45 because as far as i'm aware they have their own individual maps.
Also the cooper and c200k may have different crank pulleys with would affect the output from s/c.
As you said you have done the ve,cr,ap,rpm calcs specific to the s/c and the bugeye and are 100% happy with them you have nothing to worry about gaining your desired hp and boost target.
It is entirely up to you how you proceed with how you control the s/c but there is a good reason why all manufacturers have a a tb on intake because this is how they are designed to work and there are no conns go the other way and you lose control of the system.

I don't want to let the cat out of the bag just yet about my build because I want people to read it complete but I will say mine is capable of double the displacement on your system and considerably larger

regards mike

BlownImpreza

Urm thanks...its nice to have it confirmed that it definitely is my choice.

There we have it everyone...size really does matter apparently.

Thanks to all who have read, enjoyed, may be even shed a tear (too far?) about a build that didn't set out to create huge bhp, didn't start with decent power and added more, but whose aim was to show that with a weekend here and there, sourcing parts from left over brackets and borrowing from Fords and VW Passats, could lead to something a little different and home grown. Not the fastest car with the best parts, more the poor cousin with a good heart.

There probably is a good reason for the throttle body on a Superchargers intake, but then people used to think all cars had to have reciprocating piston designs, then a chap by the name of Felix Wankel decided actually, they didn't.

I'm never afraid of failing...only of failing to try.

I think I'll leave it there...

mickywrx

iTrader: (29)

Late reply, sorry.

No you understood my question perfectly, I hadn't noticed the filter there.

Is it not a little, well quite a bit on the small side?

silver6933

As a fellow IT person that plays spanner jockey on the weekend, I am very interested in following your project. It is nice to see someone actually BUILD/ fabricate a system.

Rather than the normal documenting of a bolt on job.


Good luck bud.

From a

Fellow bugeye owner

BLU

iTrader: (27)

As long as you're leaving it to go and tinker in the garage

I like your attitude towards this build - thinking outside the box! I can't wait to see the results and then the tweaking of the system

Don't forget thinking outside the box and challenging what is normal is how Mr Dyson has made his millions

Also from a fellow Bugeye owner

StuS

iTrader: (5)

Any news on this?

N/A Power

Any more updates on this? and are you running a sohc engine?