40 replies to this topic

[The Matt]

I'm weighing up the pros and cons of both options for a fruity little 1330 I'd like to build.

To me, the 7 port ticks all of the boxes, but what are everyone's thoughts on how they compare?

I would like to go for a really revvy little number on decent rods and crank. I just want something a bit different. The 7 port seems to be more of a standard fitment than the 8 port (cam, exhaust etc) but are the 8 ports worth the extra hassle?

Thanks in advance

[vx220]

I think it comes down to how much power you need, as to whether it's worth the extra £££

Bear in mind the additional cost involved for induction (over a 5 port) and whether space is available for this up front?

IIRC a 7/8 port makes a lumpier cam more driveable, but are you going to build the bottom end to support the higher revs?

[mini13]

ok lots of variables here,

 

what heads are you looking at?

 

The arden 8 port will (nearly always) need a special bottom end built using S rods or billet ones as the 8 port cam lobes hit the rods,

 

The Minisport/AKM 7 port has big ports and looses a lot of gas speed at lower revs so can end up being extra cammy,

 

the Specialist components 7 port, is a good head, well sized ports and flows well, and is a lot more bolt on.

[nicklouse]

I would not bother.

Mapped ignition and mapped injection on a good 5 port with correctly sized exhaust and inlets.

[The Matt]

I was looking at the Arden 8 port or the Mini sport 7 port. Also considering a KAD setup as a possible option. I do want it to fit under a standard round nose and would ideally run a custom plenum/TB or look at using Jenveys. Not fussed about a load of little holes in the bonnet to feed the air in but don't want a huge airfilter sticking out if it can be avoided.

Hoping to go short stroke crank, 4 bolt centre main, Arrow or similar rods, forged pistons for the bottom end to make it uber revvy.

It will be for nothing but fun and to build something quick. But I want it to look fairly standard externally if possible.

[mini13]

also look at the SC BMW K head conversions,

[The Matt]

Yeah, there's one of those going down at our unit at the mo. I did wonder about one of those to be honest.

[Spider]

also look at the SC BMW K head conversions,

 

I gotta agree. For the money / effort / result ratio, a 16 valve head (though not necessarily a K1100 head) is the way to go - if you want to go down this track, but as nicklouse has posted above, don't overlook a decent 5 port with a proper injection set up either.

[Orange-Phantom]

I've got the AKM 7 port on mine.  It's very driveable, great fun and revs rather sweetly.  It's fine low down and isn't too cammy and I'm running a Swiftune SW10 cam and it's just as much a bolt on as the Specialist Components 7 port although each has it's own strengths and weaknesses.

 

I've got twin DCOE 38's on the front of mine and an ITG Air filter and it's fits fine under the bonnet.

 

Ultimately everyone is going to have their own opinion and what they think is best.  The 7 port option is definitely the most bolt on whereas the 8 port requires a-lot more custom gear to make it work e.g. exhaust manifold, cam.  The 16 valve stuff can work out to be very expensive, but saying that will give you the most performance gain, there being no substitute to the breathing advantages of the 16 valve head.

[The Matt]

I think if I was going 16V I'd want it to be a KAD build really.

The cost isn't so much the concern, it's more about assessing whether that cost results in something that is worthwhile.

Has anybody heard of any porosity issues with the Minisport 7 port heads?

I'm leaning toward an Arden 8 port build after a chat with someone in the know.

[nicklouse]

Oh how I remember drooling over the KAD stuff when it first came out. I even went as far as long phone calls and receiving a quote in the post.

Overly bits of kit but then you need to make sure the rest is up to it.

[The Matt]

Oh I'm putting ideas together for a very special bottom end to get the Revesby right up!

[SiZT]

Get as long a conrod as you can whilst keeping a decent crown on the piston  as for the head, a proper exhaust manifold as opposed to one built for siamesed ports would be better but it depends on the gains vs cost

Edited by SiZT, 03 January 2015 - 04:35 PM.

[Orange-Phantom]

Over the extra exhaust port I'd like to know what other gains/benefits the 8 port has over the 7 port and how much extra power/torque this actually translates into.

 

I've not heard of any issues with the porosity of the AKM / Minisport  heads.  Would like to know why you may think there is may be an issue with Porosity with these heads over any other head on the market.

 

If money were no object I would definitely have a KAD 16V setup, they make some beautiful equipment with some rather potent torque and bhp figures to back it up.

 

My bottom end could take it no problem, custom pistons, ARP Bolts, DKE billet crank, full Miglia spec bearing straps Jack Knight SC Drop Gears, 6 Speed Dog Box.

 

Saying all that my brother could well give me a damm good run for my money in his 5 port with single Webber 45 and Kent 296 cam that he uses for road racing and hill climbs over here.  He won his class in the last Manx Classic Hill climb and this is on an engine that he built himself and has not even been on a rolling road!  (We don't have one over here).

[nicklouse]

 
Saying all that my brother could well give me a damm good run for my money in his 5 port with single Webber 45 and Kent 296 cam that he uses for road racing and hill climbs over here.

Exactly. At Hatewood it took them 11 years to best a 5 port A series in class A.


Matt how many Rpm are you wanting and what will you be using it for? Race or just Hooning?