320i Heads on Strokers

[Motorhole]

Whats the advantage of using a 320i head over a 325i head on 2.7 engine conversions? Would it also work on a 2.8 conversion (M52 crank)? Is there any benefit in fitting a 320i head to a standard 325i block?

[Geeman]

320 head mates straight up to the 525e block... though it has smaller valves than the 325 head...

[psychochild187]

im interested in this too

can a 2.5 head be made to fit or is there a way of getting another way to get a 2.7 rather than haveing the smaller ports

[Geeman]

The 325 head WILL fit, but requires work, as well as the block needing mods if I remember correctly (skimming/decking).

Best person to ask is Ian Temple (Templ8e30) I would think, but he used the existing 525e head and modified that instead.

[Templ8e30]

The 325 head WILL fit, but requires work, as well as the block needing mods if I remember correctly (skimming/decking).

Best person to ask is Ian Temple (Templ8e30) I would think, but he used the existing 525e head and modified that instead.

Giles is correct, the 320i head fits straight on to the 525e block for a cheap and easy 2.7 because the 525e and 320i heads use the same combustion chambers and the pistons are the same design (although the 525e has a 4mm larger bore). This method also requires 325i manifolds and injectors and a 2.7 chip available on the zone shop.

To use a 325i head which does give better power you'd need to rebuild the bottom end with 325i pistons that have had the skirts modified to clear the crank and also have the top of the block shaved so the pistons sit at the top of the bores. Because the block has been shaved a vernier cam pulley is required to correct the cam timing.

All in all the 325i route will cost quite a bit in machining costs.

I preferred to fanny about with the 525e head and spend 12 hours plus with a die grinder and drill press to get the ports to 325i spec and drill oil feeds for the previously un-used cam journals

I won't be going down that route again. I'd use a 320i head with the ports matched to 325i manifolds.

Cheers,

Iain T

[Geeman]

I won't be going down that route again. I'd use a 320i head with the ports matched to 325i manifolds.

That's my plan...

[dazleeds]

mine too

[JonnyBravo]

am i right in sayin if you use later 325 pistons then they dont need the skirts modified? and how much do you need to deck the block if using the 325i head? 1.5mm?

Cheers

[Templ8e30]

am i right in sayin if you use later 325 pistons then they dont need the skirts modified? and how much do you need to deck the block if using the 325i head? 1.5mm?

Cheers

The early pistons don't need mods but the later ones do.

I honestly can't remember how much shaving the block needs, think it's a bit more than 1.5mm.

Cheers,

Iain T