10 replies to this topic

[Daveb1275]

Morning all, I'm currently building a 1275 engine that will be supercharged using the eaton m45, it will be going in my 1275gt clubman.
Some advice on cams would be much appreciated. I have a couple available, standard 1275, spi, and a piper bp285.
Any thoughts / advice greatly appreciated.
Cheers, Dave.

[mini13]

Pretty sure the SPI and 1275 are the same profile, will work ok for a charger but a bit more edge wouldnt hurt. The 285 will be pretty lairy in a charged engine, basically its a full race came for a super charged engine.

 

I would sugest somthing like a 266, or SW5, the kent 274i would be really good as its on a wide LCA.

[Steve220]

If you can get hold of one, the MG metro cam works great with a charger.

[HUBBA.HUBBA]

Ive got a sw5 on mine and people say its good for a charged engine, but I don't rate it really. Its a great cam for na. I would have a look on the Podifold boost pressure calculator and go for one that reduces the boost pressure in the manifold. A cam that reduces manifold pressure means its getting better flow into the engine.

[Ethel]

A belt driven charger shouldn't be any different to a N/A engine as far as cam choice goes. You can make your power at lower rpm though, so less need to go for anything as lairy. 

[mini13]

I'm going to disagree slightly, although they will work, longer cams with a lot of overlap  really hurt MPG on supercharged engine.

[Daveb1275]

Well you've all given me something to ponder on. I think I'll steer clear of the BP285 on your recommendations.
Hubba, what would be your choice of cam, it seems your not too keen on the SW5.
Cheers.

[Ethel]

I'm going to disagree slightly, although they will work, longer cams with a lot of overlap  really hurt MPG on supercharged engine.

That makes sense. While it might not cost you any power, as it would with a turbo's back pressure, you could get the opposite blowing  straight through to the exhaust. Not only wasted fuel, but bad emissions if you want to drive on the road.

[mini13]

yep, Stu at Vmax is the person to talk at really, I know he's build engines with 286's and got some wide LCA cams done.

[HUBBA.HUBBA]

Well you've all given me something to ponder on. I think I'll steer clear of the BP285 on your recommendations.
Hubba, what would be your choice of cam, it seems your not too keen on the SW5.
Cheers.

 

I'd go for something like the Calver RE13 or Avonbar PH2 Turbo cam.

I definitely think there is a difference between NA and FI cams. My sw5 was superb naturally aspirated and took off at 2500rpm and I don't think it is any coincidence as in forced induction it bogged down in exactly the same rev range. (don't think the long inlet on the suck through helped).

I have spent may hrs and £'s working round the issue.

[Gr4h4m]

Look for something with a wide LCA of about 112. Vamp seel some supercharged specific cams, or the 274i or the Graham rustle re13t which you can get as a 112lca should work off of the shelf.