Some info on m45 charger and MPI for anyone who's intrested
Turbo Mini Forums

Hey Guys,

I just wanted to share some of my findings for anyone who is intrested with regard to the problems ive had with my supercharged mpi.

I was running the standard VMAX 150mpi kit with the Emerald M3d K3 ECU, both quality items and fitted by vmax

After a final session for a few tweaks with Dave at Emerald today its now about as good as it will get.

Ive had to make the following changes to the base kit:

1) Fabricated a new intake pipe to reposition the IACV across the throttle body as its supposed to be. Also i made sure that the full bore diameter wa maintained along the length of the pipe including at the charger mouth.

2) Modify the inlet manifold to allow fitment of the following,
a)MAP sensor,
b) IAT sensor

3)Remove all the additional recirc pipe and drop the boost by fitting a bigger pulley (as advised by the guys on here)

4) Install Vmax charge cooler kit.

5) Install deep dish forged pistons to drop compression and get rid of the need for spacer plate and 2 Head gaskets


Mine was originally one of kits which runs the standard BMW charger pulley. On a 1293 with standard mpi pulley this developed 18psi without recirc or 13.5 psi with the recirc, this made approx 135bhp but suffered awfully from det with charge temps up to 110 degrees!!!!- Resultantly i screwed a piston crown (when still standard 1275 mpi items)

Ive now dropped the boost to 9psi (without a recirc) thanks to the bigger pulley and have consequently dropped charge temps to circa 60 degrees (still high i know but we can deal with it now) Amazingly the car drives far better throughout the rev range and has only lost 5bhp!!!

In honesty it drives like a standard car but goes like bloody stink now.

I hope anyone going down this route can find some of the above info usefull but if you need any more detail/reasoning please ask, or see my other posts.

Cheers for all the help guys
Andy

Glad its sorted. loosing 5hp doesnt matter when the drive is so much better. That was a similar drop in power when I went with the programable ECU, power dropped, but torque increased where it mattered.

There should be medal for your efforts! whats that now, your fourth trip to Emeralds rollers? with all the extra engineering and you still havent thrown in the towel. I'll bet you are itching to get out and use it :)

I'd still be tempted to fabricate a charger/ manifold intercooler take off spacer and inject after the intercooler

Perhaps you should sell the design to Stuart at v-max!

If something is worth doing, it's worth doing half of.

Hey Guys,

Yeah it was my 4th trip to emerald and i really cant rate daves work high enough.

Your right sprox, its certainly worth losing 5bhp for what its gained elsewhere and in general useability. In honesty ive learned shed loads which i didnt have a clue about on this and now i know a little about charge temps etc and boosting engines i have a few ideas to make it even better.

The main plan is to do as you say and lift the charger to allow the fitment of a take off and then get an intercooler in there. Ive gained a small oil leak which i think is from the crankhalf moon seal so will be pulling the engine out over winter anyway which will give me chance to get everything fabricated and trialed to fit,its a bit tight when its all in there! I think i will go with a carbon fibre bonnet then and just lift it a little at the back to give clearence for the charger.

Doing this would also give me chance to get the boost back up again as well and probably deliver some decent power gains once i get an intercooler on.

Im quite happy to share any of my findings with anyone and would happily show them to Stu at Vmax but he would have to at least make it worth my while travelling all the way down there

I think it would be pretty special and a decent bit of kit if i get an intercooler on there as well, also there would be no reason why a reasonable home mechanic couldnt do it all themselves!

Hi Andy do you have any pics of your car? I am away to embark on a similar build. I am looking to change fro carb to injection. Any pics would be great

This proves what I (and others) have been saying the maths predicts when using the Eaton.

4.5psi only gains you 5bhp, not worth it.

4.5psi gets me over 40bhp gain on my 998 with the turbo.

Good work though, thanks for sharing the info.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

Andy.

Good news mate. Well done.

What was the final torque figure ?

Richard.

Minivanless, but reluctantly happy living with the decision. There'll be another one day.
http://www.youtube.com/profile?user=minimadmotorman#p/u

Cheers Guys,

Lockfast i will get some pictures uploaded over the weekend theres also a few in the gallery i think.

Will, your dead right and i cant thank you guys on here enough for the advice over the past couple of years. In reality ive dropped the boost from 18psi so its a 9psi drop with only 5bhp loss! which shows how mentally inefficient the m45 is at boost anywhere above this!

Its set up quite well now to allow nme to play with things abit so i think im going to have a shot at getting an intercooler in there as well over the winter and then experiment with different boost pressures next year....should be intresting

Richard,

Will post up the final bhp and torque figures once i get the maps from Emerald, i will also stick up the previous ones for comparison.
Thanks
Andy

Very interesting thread Andy, it sure convinces me that blow through is the only way forward!

I wonder how the eaton would perform at 13.5psi with a decent intercooler

Can I ask what this recirc stuff is all about?

I've got an M45 to go onto my new engine when i built it, and It'll be running blow through with an intercooler.

Looking at the charger, it looks very mechanical with no form of recirc or anything like that built in.

if there is something built in, how do i stop it?

Mr. Prawn, the friendly Crustacean- slowly making steps towards forced induction.

I'm think along the blow through s/c route for my second engine (further down the line). Was looking at a different charger to the E45 though.

Hey Prawn

Stu at vmax adds an additional recirc by drilling in to the side of the outlet from the charger and piping this back to the inlet side.

The chargers do also have an internal recirc, where the air can bleed back past the rotors, you can see how this works by looking at the outlet and giving it a bit of thought. This is primarily for economy though i believe and when on low/no throttle and removes the requiement for a BOV.
When i mention the recirc im talking about the additional one fitted by vmax, i no longer run this and its blanked off!

Wheres those piccies ?

I was trying to build a charge cooler plate to site between the charger and the manifold. Put a extra rad at the front. Never got round to it though.

Interesting about the recirc. All I can see this doing is putting hot air back into the charger meaning it'll then superheat it. I wounder what the actual theory is?

If it's there just to drop the pressure, then the pulleys are the wrong ratio.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

I setting up a recirc valve on my suck through rotrex, will using a dumpvalve (or maybe 2) adjust it to be fully open at idle
maybe it will open a little on full boost, haven´t tried it out yet

internationally known as "big" swede

Find these step by step tech articles very informative, well worth a read if you are going sc, last link covers the "dump valve" bypass

http://autospeed.com/cms/A_2511/article.html

http://autospeed.com/cms/A_2512/article.html

http://autospeed.com/cms/A_2513/article.html

http://autospeed.com/cms/A_2514/article.html

Edited by G13B on 10th Sep, 2009.

internationally known as "big" swede

Dump valve on suck through That will just blow of your air/fuel mixture into the engine bay!

On 10th Sep, 2009 G13B said:
I setting up a recirc valve on my suck through rotrex, will using a dumpvalve (or maybe 2) adjust it to be fully open at idle
maybe it will open a little on full boost, haven´t tried it out yet

Do you need a BOV on a rotrex? as it's a centrifugal type SC it'll be making bugger all boost at idle wont it?

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

ap: recirc dump for crying out load!

Will, when downshifting you get a big amount of vacum infront of the throttle, i using slide carb to and i guess fitting a recirc will help operation safe sc seals + charger will get colder when trottle is shut/cruising

internationally known as "big" swede

Of course, I hadn't considered that it's still be moving lots of air at high rpm with the throttle closed.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

G13B, this recirc valve is really interesting. What one are you going to try? Would love to hear how it works out.

Would the recirculating dump not cause overfuelling when you re-open the throttle due to all the atomised fuel in the dump?

If something is worth doing, it's worth doing half of.

moke: i´m going 34 mm forge type, or double saab diafragma types (25mm), problem with the saab ones i don´t know if they will stay open at idle, with the forge i can clip/switch out the spring to create a "custom" valve,

minimadmotor: well there is no fuel when the trottle is shut, just the little that recirculate, i would figure that such a small amount will work as a acc. pump when booting it

internationally known as "big" swede

Sounds like a fair thought G13B.

You will never know unless you try.

If something is worth doing, it's worth doing half of.