supercharged engine spec?
Turbo Mini Forums

Hi everyone i,m in the process of building my engine up, it`s a 1340 block, omega dished pistons,uprated box,etc
I,m thinking sw5 cam ?
and also the final drive, Ive got a vanden plas engine at mo trouble is im running on tens and to be honest would like a bit more top end,i think the standard vanden plas is 3.44?
if so would a 3.1 be enough of a difference ? thanks for your ideas Stu

And just out of interest how many nanas do u reckon ? its 9.01 compression, no decomp plate here! 1.5 rockers 10% pulley so should be running bout 10psi

If you're running any sort of close gearkit, a 3.1 won't be nice. The VDP is a 3.44 and I would leave it alone.

If you've got leggy gears, I'd perhaps consider a 3.2 (turbo FD). I'd steer away from the SW5 as in my opinion, it doesn't have enough exhaust duration. If it's low torque you're after, try an MG metro cam. The step up in the right direction is a Kent Ph2 turbo cam. Leave the 1.5 rockers out of it with the Ph2.

You want to trap the gases at low speed and have enough exhaust to clear it properly allowing higher revs as well. I'm convinced that a short cam with insufficient exhaust "area" strangles it at higher RPM.

I'm rebuilding mine with a 3.7FD as I have a 2.54 1st gear. It won't go very fast but it will get there faster.

Are we talking an Eaton M45 blower as well?

Bugger off, I'm getting there.

thanks for the reply HEDGEMONKEY it makes sense what youre saying I Was also considering a 270 piper as its the next cam profile up from the cam i have at mo . What do u reckon 130 ish bhp? does anyone else have running probs ? it seems noone can get the damn thing set up properly on their rollers! fluttering bad idle fouled plugs etc Thanks again

The piper 270 has 276 inlet and exhaust, not enough exhaust or too much inlet in my opinion. Stay away from symmetrical cams profiles. The Kent 276 is a better bet with a shorter inlet, longer ex and more lift on the exhaust. It would work better.

Of course, anything works well with boost, but if you're going to make the most out of it, you need to have this cam characteristic. I've looked at the theory and compared it with a load of maths and it's like having a 32mm exhaust valve for area for flow with an extra 10-15deg on the exhaust. Obviously, with a bigger exhaust valve, you could use a shorter exhaust duration.

I did my work assuming S sized valves as I'm too much of a skinflint to go redesigning my head.

The more duration/overlap you have, the more of a slut it will be to get running properly at low revs.

I'd say (but am no means qualified to) that the sooting up of plugs and shitty idle was due to an ignition way-outness.

If you root around on here from years ago, there are my technical thoughts on doing it in huge detail. Obviously not the definitive right ones, but an individual take on it....

Good luck, stu

Bugger off, I'm getting there.

Ive got 36mm inlet and 29mm exhaust so this should be ok Stu reckons its got a 23cc chamber volume. so im thinking that head with 10cc dished omega cast pistons ill have the reliability and with 1293cc also 8:5:1?