mbc

[shaunturner306]

I have fitted a mbc to my hdi as it is now front mounted what boost should I be running as standard as I havent mapped the car yet

[ADV_93]

13/14 psi, althought may get a drop of 1 or 2 psi if it's FMIC'd

[Slam Wagon]

shouldnt have a drop at all, should still be feeding the intake the same pressures. may just take a bit longer to boost as theres a larger volume to fill.

[Poodle]

Theoretically if the intercooler is 100% efficient you wouldn't have a pressure drop, but that's physically impossible lol. 1-2psi loss is about right.

[shaunturner306]

I havent run the car since it was fitted at the garage this morning an may have to adjust the mbc as I dont no what boost its running at yet

[Poodle]

Just wind it all the way out and it'll put all the load on the wastegate, therefore working as normal.

[shaunturner306]

Ok thanks

[ADV_93]

You don't wanna boost too much or else you'll blow the welds on the intake

[shaunturner306]

So whats the best way to adjust the boost with out driving the car

[ADV_93]

Best way is to drive to car. If you have a boost gauge installed, set the MBC to it's lowest "-" setting if it has one. Then give it a click, or a turn, then drive off and see what the increase in boost is. If you're still running standard atm, messing with the boost could make the car run funny.

[shaunturner306]

The car is standard just getting ready for stage but I dont no how the mbc was set be it was installed

[ADV_93]

The car is standard just getting ready for stage but I dont no how the mbc was set be it was installed

Not a problem, do you know what type of MBC you have had fitted? Can you send a picture?

[shaunturner306]

Its a turbo revs one off ebay

[ADV_93]

[attachment=18394] Is it this type? If so, the silver bit on the ends twists. If you look on it, it'll have a "+" and a "-" with arrows pointing in the direction. If you twist it toward the "-" but go probably a click or two off the bottom then the mbc will barely have an effect and it will boost off the normal actuator pressure.

[shaunturner306]

Thats the one mate in sliver cheers

[Poodle]

You don't wanna boost too much or else you'll blow the welds on the intake

Never heard of that happening before, who was that?

[shaunturner306]

Cars running but its only boosting at 10 psi underload even with mbc open full soundd like theres a boost leak but cant find where its coming from

[Piggy]

Probably to do with that crap MBC.

Get a decent brass n ball one and you may find it sorts itself

[shaunturner306]

Tbh mate the bloke at the garage who fitted it has never a mbc to a diesel an im not sure if its plumbed in right

[Jtrigga]

You don't wanna boost too much or else you'll blow the welds on the intake

Never heard of that happening before, who was that?

Brian o conner

[Piggy]

Tbh mate the bloke at the garage who fitted it has never a mbc to a diesel an im not sure if its plumbed in right

Serious?!

1) you paid a garage to do it?!

2) he wasnt sure how even though he had done petrols!?

[Poodle]

Brian o conner

*facepalm*

That went completely over my head.

Not boosting enough is very unlikely to be the mbc at fault, i'm not sure that's even physically possible lol. More likely a boost leak, poor piping or knackered turbo.

[shaunturner306]

I havent paid him yet an only found 2 leaks an pipe work is fine an nothing wrong with turbo

[pro_steve]

If you've got the one from that picture (bleed valve) they have to be plumbed up differently to the normal ball and spring MBCs, here's a simple guide for each type that you can show your garage (I think you have the second type): http://hdi-tuning.co.uk/downloads/MBC-Me...-guide.pdf

As for setting up the boost it's not a big deal.
Get your stage 2 map on there then start with the MBC screwed out all the way. Drive the car hard and see what the boost is at. Stop, screw it in a bit then drive again until you get to 20 psi once boost has stabilised.

Don't push much past 20 psi as this it's not beneficial and you'll just end up killing the turbo.