Scatter Pattern cam for 7 port crossflow
Turbo Mini Forums

Hi

What's peoples thoughts on running a Scatter Pattern cam on a 7 port head. Any real adverse effects?

I've been recommended and bought a certain cam, unaware it was a Scatter.

I rang the well respected Engine builder / supplier to question why they sold me a cam developed for a 5 port engine. He reckons it showed more power than the none scatter when they tested it on a 7 Port and it will work perfectly. He claimed due to the shared exhaust port.

Now surely the exhaust fires 180degrees, so no benefit wot so ever.

I'm now, in 2 minds to get a refund.

Edited by alaskanow0 on 7th Oct, 2014.

Class C 3rd Place Avon 2011 14.18 @101mph

Scatter cams were developed to minimise port robbing on a five porter if i remember correct. Cant see it being helpful on a seven port

Do they have any evidence to back this claim up, back to back tests etc?

Class C 3rd Place Avon 2011 14.18 @101mph

Send it back. Scatter cams are to even AFR across the inlets. The exhausts are not scattered I don't think?

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

www.twin-turbo.co.uk

Exactly my thoughts.

Class C 3rd Place Avon 2011 14.18 @101mph

Sorry if i sound dumb but what exactly is a scattercam? I have driven a mini with one n hell it was lively but whats the difference?

agreed, why would you want two cylinders to perform worse than the other two by using a cam for a 5 port head with the charge robbing problem that the scatter cam was designed to reduce the effects of

With the scatter cam, the valve timing is different across cylinders to reduce the effects of charge robbing as a result of the significant inlet valve overlap. A normal cam has the same valve timing across all four cylinders.

Ummmm, if you study the yellow bible, Viz suggests that on the more advanced scatter cams the centre exhaust timing is different and hence changes the LSA to suit the siamese exhaust port.

Just saying and have no opinion either way.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

I will be sending it back tomorrow. I honestly didn't think it was a Scatter Pattern, it was only the SP on the timing instructions that gave it away.

The annoying thing is I even said to them. ' I can't use the MED one because it's s scatter pattern'

Edited by alaskanow0 on 6th Oct, 2014.

Class C 3rd Place Avon 2011 14.18 @101mph

I was thinking the same Paul,

if they are testing it against a std pattern cam that has a shit LCA, and 2 of the scatter cam cylinders have a better LCA then it will test better...

still not right though...

Any body had any experience with the 649+ ?

Class C 3rd Place Avon 2011 14.18 @101mph

There's an element of snake oil about scatter pattern cams, but there is also some truth that in the right application they can produce marginally better power.

Fact is, the centre exhaust valves see a different pulse pattern to the outer cylinders due to the siamese exhaust port. It then follows that a different exhaust pattern cam may produce better results.

The whole concept of charge robbing reducing total power output is flawed anyway.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

I see what you're saying paul. If the most advanced scatter cams do indeed have 'scatter' on the exhausts then there may be some benefit.

However, there is no point on the inlets. What you really need is a cam that is specifically designed for the 7-port. i.e scatter on the exhausts and equal inlets (this might work it might not, I have no evidence either way). Not a cam that exists anyway.

The fact that the seller has suggested that the cam worked well might well be shown in an RR graph/graphs, but you never really know what is being compared.

As is usually the case, choose a cam that will put the power band where you want it.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

www.twin-turbo.co.uk

Also, never spend more than approx. £200 on a cam.

Kent will grind whatever you want from a billet for that sort of price as long as you use existing profiles. Timing can be whatever you want.

Well, that's what I did for my custom ground scatter cam about 4 years ago. May have gone up a bit since.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

while i don't have 'data' to show the the two centre cylinders make more or less power with a scatter/ different timing...do any of the ECU's on minis individualise timing/fuel to see what each cylinder wants?

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

thank you paul S, that is good info sorry to OP, carry on