Hi All,
 
Ive recently just purchased a Beams motor for my car and am looking at rebuilding it with the package that gorilla has for sale,

Question regarding the pistons, i want to upgrade them to something a little more aggressive than stock but not sure what size or compression ratio i should go.

The car will be staying N/A and will be seeing a fair bit of track work.
 
any suggestions?

Size, fit what ever your bores clean up at. If just a hone is required then stick with 86mm. If not the bore out the minimum to 86.5mm.

You will need custom pistons, std CR is 11:1, black top is a tad more.

Are you fitting an ecu also? If so then you could go to 12 or 13:1.

thanks for the info, 
 
at this stage ill be sticking with the standard ECU. 

sticking with the standard ECU then you are best off leaving it with standard compression. From my experience stock ECU's don't like big upgrades in comp ratios. sure they can work, you just have to be willing to sacrifice timing and power so that your engine doesn't detonate itself.
 
on my old 4age I had upgraded to higher comp pistons on the stock ecu. I had to run a very easy tune on a set of cam gears and had to retard ignition timing to about 9deg BTDC on base time just to stop the engine smashing a ringland. So the differance in running the higher comp was a complete waste of time. and this was going from 9.4:1 to about 10.8:1

You can go higher compression pistons but counter it with a  thicker head gasket. That way when you do a programmable ecu all you have to do to bump your compression up again is go to a thinner head gasket.
Keep in mind when your buying pistions if you overbore your engine the compression ratio jumps up also and if going for higher compression pistions just make sure there are no issues with your valve to piston clearance.

thanks for the info guys.
 
i had a think about it over lunch and am now deciding to go with the aftermarket ECU , if im building it up might aswell do it right from the beginning 

Why do you want to build a N/A track car?

track_mr2
Why do you want to build a N/A track car?

Simplicity, Reliability, Lightweight, Personal Preference.
Plenty of reasons :)

Knightrous

track_mr2
Why do you want to build a N/A track car?

Simplicity, Reliability, Lightweight, Personal Preference.
Plenty of reasons :)

I know there are good reasons for doing it but there are also good reasons to go turbo over N/A. Just curious as to why they have chosen to go N/A as opposed to turbo. Being a beams engine I'm assuming they planning to put it in a SW20 which are't the lightest cars going around, especially coupled with the power the beams engine put out.

My  Beams SW0 has no power steering and no ABS, so it weighs in at around 1120kg (according to the rego papers), which isn't exactly fat. In fact, with the 200BHP BEAMS Red Top, it has a better power-to-weight ratio than a standard Lotus Elise S... and because it doesn't have a turbo, there's no lag in the throttle response and no ugly 'power surprises' mid corner.
 
All that adds up to a good reason for Voodoo to do what he's doing in my books!