Increasing the boost
Turbo Mini Forums

Hi,

As far as increasing the boost goes, what is the most reliable and safe method of increasing the boost?

Any advice appreciated,

Cheers, Tim

89' Metro Turbo
157 BHP , 170 lb ft @ 15psi .... So far....
Mikeanics Rolling Road
WINNER OF RETRO CARS SHOW BEST 80's MODIFIED CAR

There are 2 main ways

1). Modified actuator

2). Bleed valve method (under bonnet or dash mounted)

IMO

The best way is to use a modified actuator, as non of the boost pressure is bleed off to atmosphere, you can get these from Avonbar and various other mini speciallist.

The pressure is set by adjusting the pre load, by adjusting the length of the actuator arm.

The bleed valves are cheaper, but as the name suggests bleeds off the boost pressure which is being used to actuate the wastegate actuator, thus allowing the boost to reach a higher level, the amount you bleed off dictates the level of boost reached.

If you want to increase you boost pressure you will have to make several modifications to your engine or you will damage it.

First of all choose the boost pressure you want. You must stick to it (10PSI for example)

Then you will have to do the following (Briefly)

1). Reduce your CR, this is achieved by either using pistons with a bigger dish or increasing the volume of your combustion chambers in your head or a combination of the 2. A figure of 8.5:1 would be a good start. Recommend using a BK450 Payen head gasket. Also you should consider having the deck of your block surface ground and also the cylinder head face. You should also make sure the bottom end of the engine is in good condition.

2). You will have to change your needle and spring to high boost types ie 10PSI Rating, and uprate the spring in the standard dump valve in the plenum chamber.

3). Uprate clutch and diff.

4). The fuel regulator will look after itself but you should have the engine properly tuned on a rolling road to be sure of the mixture across the rev range and also to optimise your ignition timing. As when you up the boost things tend to burn out very quickly if every thing isn't 100%

This is just the start, but there are plenty of people on here that can advise on more specific questions, but as you can see you cannot go about this lightly....

Cheers Brocky

Edited by Brocky on 17th Nov, 2005.

BTW - I took my buddy VTEC Pete out for a spin this weekend, and even though I am running her in, he gave it a name, the "Brocket"...cause I'm a brocket maaannn, nah nah nah nah nah nah nah nah nah nah nah....

Build thread - http://www.turbominis.co.uk/forums/index.php?p=vt&tid=7483

Katy Mini Owners Club Thread - http://www.turbominis.co.uk/forums/index.php?p=vt&tid=505552

Let's make sure you embarrass at least one VTEC MINI today !

https://www.facebook.com/groups/17557298589...096464253807802

Increasing the boost is simply a matter of fitting a bleed valve in line to the wastegate actuator to bleed off some signal pressure, so the actuator does not open at the pressure it used to.

However, you need to make sure that the rest of your engine will cope with it, simply turning up the boost on an unknown/old/tired engine is a recipe for "KABOOM!"

i second that.....lol

Am i right in saying that the standard ECU operates at a 4psi boost pressure, with an overboost of 7 psi?

Does this mean that there is 4psi of boost pressure nornally, then after a set rpm is can increase to 7psi? Say 4000rpm for example?

This may sound silly, but is there a way of having progressive boost without the ECU?

Edited by Metro Turbo on 23rd Nov, 2005.

89' Metro Turbo
157 BHP , 170 lb ft @ 15psi .... So far....
Mikeanics Rolling Road
WINNER OF RETRO CARS SHOW BEST 80's MODIFIED CAR

You're right, yes. The actuator is set to 4psi, but when 4,500 rpm is achieved the ECU bleeds some of the actuator signal off, allowing the boost to increase to 7psi.

Phil.

WWW.TURBO-MINI.COM