Yet another BMC A- series mod this time for supercharger.

Competition engines and ancillaries - general discussion
Post Reply
SirYun
Posts: 81
Joined: June 22nd, 2006, 9:42 pm
Location: Maastricht, the Netherlands & Zyfflich, Germany
Contact:

Yet another BMC A- series mod this time for supercharger.

Post by SirYun »

Hi.

a short report on a lower compression 5 porter head, i will try and add photos and text as the project slowly moves along.

I was asked if i could have a go at converting a head for a supercharger conversion.

A kit sold by several companies uses a decompression plate ( and two headgaskets) to lower the compression ratio.
The owner found this idea not too enticing and asked if i could try and lower the compression of a head as well has make it breathe a bit better.

GOALS:
1# lower compression as much as possible while staying well within the limits of the casting (including core shifts).
2# improve breathing by reworking the ports.

Method:
1# lower floor, cut out beak region, cut back chamber walls.

Result:
1# increased volume from 23 to 28 cc with minimal deepening of the chamber ( which is bad for the approach of the port to the seat)
2# work in progress
Attachments
two chambers roughly finished and matched. i used a high speed router and a large mounted point to grid the chambers to a set depth. a methods wich has proved to be easy and very accurate due to the micro meter adjustment and the straight valve setup
two chambers roughly finished and matched. i used a high speed router and a large mounted point to grid the chambers to a set depth. a methods wich has proved to be easy and very accurate due to the micro meter adjustment and the straight valve setup
head-supercharger.jpg (72.97 KiB) Viewed 4838 times
Joost M. Riphagen
SteveninNI
Posts: 23
Joined: November 26th, 2007, 5:09 pm
Location: Northern Ireland (A)
Contact:

Re: Yet another BMC A- series mod this time for supercharger.

Post by SteveninNI »

I have done several heads around that chamber volume when we were running a couple of clients in the Group A metro turbos in 90s... over 200bhp was attainable but the drop gears never lasted very long!

good luck with the project.
SirYun
Posts: 81
Joined: June 22nd, 2006, 9:42 pm
Location: Maastricht, the Netherlands & Zyfflich, Germany
Contact:

Re: Yet another BMC A- series mod this time for supercharger.

Post by SirYun »

the head is very much in developement stages and need tons of work. I have finished the one intake port and that has to be copied to the other siamese port. i'm allways suprised how hard it is to copy the shape and the dimensions along a port to a new port



it has since moved on quite a bit and i hope to get this one done as well as a new, more elaborate version of the 12g202 i did. After that i finally get to build something for myself..a new short block for my new project (modified 1380 cc A+ with a 16v bmw bike head. projected power 125-130 bhp at a leasurely 7800, torque about 130 to 140 NM).

you're S.Gault are you not? I would like to pick your brain about a few things..
Last edited by SirYun on January 26th, 2008, 1:56 am, edited 2 times in total.
Joost M. Riphagen
SteveninNI
Posts: 23
Joined: November 26th, 2007, 5:09 pm
Location: Northern Ireland (A)
Contact:

Re: Yet another BMC A- series mod this time for supercharger.

Post by SteveninNI »

I am indeed Steven Gault.

Guys site is great isnt it!

Good luck with the new project. Should find that hp easily
Post Reply

Who is online

Users browsing this forum: No registered users and 41 guests