54 replies to this topic

[mike.]

I really do love the idea of the BMW head conversion but there is a lot involved and the 7 port will work out cheaper like phil says.

Also if you inc VAT and SC providing a head for you it'll be closer to £3500

[jamiestevenbell]

ok wel ill have a lookinto an 8port too whats best of the 3i would rather spend the extra 1k end be totally satisfied

[MJWarren]

Theres no point paying all that money for a 7 port head and not running it injection. The main advantage of them is how well suited they are to injection.

Using the parts from other cars, I don't think injecting it will cost as much as a set of webers and then the tunability you'll have will be great. The good thing about injection is you can tune the fueling and timing perfectly for your spec across the whole rev range and for different loads on the engine. You can't do this with carbs and a dizzy.

With injection you'll be able to improve the drive ability of the car and make the cam less lumpy too.

I agree that fuel injection is better. But at a cost.

The advantage of fuel injection over webers is you can very accurately set the fueling at smal throttle openings, which is where on a road engine your operating quite a lot of the time. Webers often have to be set rich at this point as a consequence of getting the fueling right for max power, this makes a carbed engine very uneconomical when your just tooling around.

With a 7 port head you can put a single throttle body on and yes you can map the fueling as stated above. But why would you do that on a n/a engine. The whole idea of the 7 port head isnt for the ease of fuel injection as i see it, its for the X flow head which allows you to use a choke per cylinder.

Yes if you have the money put it on Fuel injection this would be ideal, if not go for webers. In my opinion single throttle body wouldnt even enter my mind.

[jamiestevenbell]

ok wel ill have a lookinto an 8port too whats best of the 3i would rather spend the extra 1k end be totally satisfied

[summs116]

wel from my engines i had a 110 bhp at fly with 1330cc,piper 649+ cam large port 36 31 valves webber 45 with all the other bits and it was a fantastic fast road trackday engine,revved it to 6800,done 5k and still had the same power 18months later,cost 2.5k

my 7port twin weber 45s 1380 296cam steel rods steel crank all the best bits revving to 7800 had 139bhp 108ft tourque,not really any good under 3.5k was trackdays only and the odd road thrash.rebuilt it every winter, simple rings oil pump bearings lap in valves and they last forever.cost was 5-6k

my arden 8port is total different.rally engine and built for tourque and drivability. with the 8 port you got great expense eg.. the head,rockers camshaft exhaust manifold,inlet manifold push rods head bolts.piston and con rod machineing.plus all the crank rods ect.cost wise 8.5k and 125bhp 118ft tourque

my lastest 5porter all steel full race revs to 9000rpm with 135bhp and 106 ft cost 15500k.rebuilt every 3-5 meetings and runs on 4star petrol at £2.10 a litre and 1 race is 40 mins with 30 mins qualifying
swiftune built

all engines have sccr swift dogbox's drops and tran x lsd's

as already said yours sounds fun but i know how you feel.always want more power.
i personally would leave your as it is. find another lower half,and build it up over time
do it once properly and it will last,its all the little things that make it strong,shot peening,arp fixings,line boring 4 bolt straps nitroding the crank and camshaft.balance componets.

[Turbo Phil]

If you want to use it on the road you could build a decent 130hp Turbo motor for far less than an equivalent powered NA motor, plus the Turbo motor will produce much more torque, you won't have to rev the nuts off it & it will be totally street useable.

[Ian2988]

Hi, new to the forum. Just fitted MED seven port to my 65 S. spec as follows:
MED seven port 37/30 head 11:1 CR
Twin weber 40's
1293 s block crank rods
Aldon red dizzy
Str930 (649) billet cam
Full roller 1.5:1 rockers
Maniflow stage 2 lcb
Maniflow works replica exhaust

On its visit to the rollers it made 105hp at the flywheel, and 89ft lb which I'm a little disappointed with.
Anyone able to offer an opinion on this before I speak with MED?

[bmcecosse]

Can't say I would use the 1.5 rockers with that cam...... And what size chokes are in the carbs?

[Ian2988]

Really? MED thought it was a good idea ha ha! The chokes are 33mm again as per MED's advice...

[Turbo Phil]

I don't see why the 1.5s won't work with that cam, afterall the 649 is a little short on lift.