53 replies to this topic

[who_loves_the_mini?]

I did a quick search but couldnt find the thread I was thinking off, i may have dreamt it. So... Lets start a nice factual and healthy debate, pros and cons of the above 3 heads in fast road form, on a 1380 if need be. What carbs or fuel injection should be used, a rough spec of each engine and why one is better than the rest

[pikey7]

Just my thought. I may be wrong.......

5-port
+ cheap (as in free if you already own a mini!)
+ well known
+ cheap (relatively) carb setup
- does not have potential to breathe (and therefore perform) as well as the others

7-port
- Its sold by minisport
- no-one really knows yet if the casting issues have been fixed
- expensive for what it is
- expensive twin carbs needed

8-port
+ loadsa potential for high power
+ bill richards can tune them!
- expensive
- expensive twin carbs needed
- different cam needed (IIRC, it uses completely different timing.....?)

As I say, I stand to be corrected. My comments are just what I recall from old posts over the various boards.

by the way, I'll be going 8-port!

[Jammy]

I think Pikey7 has summed it up pretty well there! If you ask me theres 3 choices; tuning 5 port, 16V head (Morspeeds devlopment or KAD 16V), or 8 port in which case your talking about the Arden cast which a number of well known engine builders can do for ya, and Bill Richards is well renouned for building these 8 ports.

5 port tuning is going to cost the least (relatively), and if you keep if NA then your looking at a maximum power of about 130-140bhp which will cost you upwards from 2.5k depending on where you go (don't go to MiniSpares, MiniSport, MiniSpeed, they are parts suppliers, not engine builders!).

16V I think just has the edge over 8 port interms of power, but I believe it costs a bit more. The Webster brothers have KAD 16Vers each with 165bhp and 185bhp and they are really quick. Expect a built engine from KAD to cost upwards from 8k depending on spec. Simon at Morspeed has recently devloped a 16V head. I believe the conversion kit costs about 2.5k, so add that to the cost of a short and gearbox, etc. I think it would be slightly cheaper than KAD in the end though.

Then you have the traditional 8 port. Personally my favourite since it has heritage going back to the glory rallying years. Don't go for the Weslake head, the angle of the exhaust manifold makes them prone to cracking. The Arden design is superior, and you can get many engine builders to create you an engine with this head; Bil Richards (as recommended by MiniSpares), MED, Morspeed, MBE, etc. When I went to Bill Richards to see if he could 8 port my 1425 he said I could expect about 170-180bhp and twice the amount of torque I currently have (so near to 190lbl/ft!!). Expect an 8 port engine, fully built to cost upwards from 7k.

[pikey7]

I'm also gonna mention the word Turbo.

I have some experience with tuning turbo cars, and based on the 944 turbo we tried things out on, the 16v head actually LOST power compared to an 8v head with similar flow "numbers". Why this is, we haven't quite figured out yet.

Whether or it was the combustion/inlet chamber shape, or the huge turbo, or just that the twin-inlet doesn't like it is a question I don't have the answers to, needless to say companies like Suzuki have smaller capacity/smaller turbo 16v that work fine....... (so it was probably just me! )

[Dan]

When the Dutch (or was it Danish, I forget) designed the 7 port head the idea behind it was that it was supposed to give you improved breathing on the inlet side by loosing the siamesed ports and giving good carb options, while allowing you to use the vast selection of standard type uprated Mini cams available at a massively reduced cost compared to the 8 port casting. The minor drawback of it was having 1 siamesed exhaust port. In essence it was supposed to give you all the good points of the 8 and 5 port heads rolled into 1. By hugely increasing the price Mini Sport have shot themselves in the foot a bit and the only advantage of it now over the 8 port is the bigger choice of cams.

And don't forget the Jack Knight 16 valve too, the price on that is supposed to be coming down massively this year. If they EVER get their new website finished then I suppose we'll ge tto find out more about it.

Edited by Dan, 08 March 2006 - 01:39 PM.

[Jammy]

A lil OT: But has JK gone under new management or something? A while back there was tqalk of them disappearing, and while that talk has gone it seems JK aren't the force they used to be??

[Dan]

They went through a management buyout. The son of Jack Knight came back to the newly formed company and has started a lot of design work. They are back to being as strong and brilliant as they were in the past. They are now making a power steering system for all new Morgans which thay also sell as a kit for old Morgans, they make the steering and gearboxes for the new A1 Grand Prix series which as I'm sure you know is a single car series so they supply all the teams and are generally getting better and better since October last year. Could do with getting a new website company though as they promised the site would be finished in December and it's still not all there. They are promising lots of cool new Mini products this year and have re-tooled a lot of the parts for the 16v head making it cheaper to produce.

[who_loves_the_mini?]

Just had a look on the minispares website and you can get the 8 port head and carbs for just over £2k which is only slightly more than the minisport 7 port, how can minisport charge so much?

only problem with the 8 port is the need for extras such as new cams etc, the 7 port dont require these

Is the 7 port head worth the hassle of doing or would it be better just to stick with the 5 port and dream of the 16v?

[pikey7]

As I understand it from the minispares site, the head assy is £1700 and still needs some work on the chambers (prob another £2-300), the cam is £260, the amal carbs are £520 (webers would be more like £1.5k inc manifolds), exhaust manifold is £260 and then you'd need things like cables, filters, gaskets and little bits. That would probably be around £3.5-4k total.

The only things you save on the 7-port is the cam, the exhaust and the rework.

But then that's just bolting on the bits yourself. The trick is in getting the balance of the complete motor right (which would mean paying a proper builder ca £7k)


Swings & roundabouts really........

[Oldskoolbaby]

Im building up a 7 Port at the moment and I bought it from Minisport because Ive heard and read much more positives than the rest. Reading the Big Yellow bible of Dave Vizard, he says one will not require alot of work to get 150bhp and if a suitable C/r and cam is used 185+bhp is on the cards.

As for the siamese exhaust problem

The minor drawback of it was having 1 siamesed exhaust port.

This is non existant. It is actually beneficial apparently. Its to do with the exhaust pulses at certain revs. Ill dig out my bible and give some more indepth info on this.

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[Oldskoolbaby]

Id much rather have the front end of my mini look like this....................no comparison really........is there?

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[who_loves_the_mini?]

Id much rather have the front end of my mini look like this....................no comparison really........is there?

hell yeah, would much rather have that than a vtec, although i wouldnt say no if someone wanted to buy one for me, lol

I really want a 7 port head now, big power benefits of the 8 port but with the ability to use the 5 port cams etc.

Oldschool - just been reading your project thread and those carbs look amazing, i love them. Just wish I had enough to get an engine like yours

[Oldskoolbaby]

As Im only 20, it does seem like a fairly expensive hobby I agree, but its money well spent .

Ive heard loads of good things about the other coversions but this one suited me better than the rest. I know this may sound petty but one thing that was important to me was that the exhaust note must sound like a Mini's exhaust note usually does, all be it a bit louder. Because of the 3 exhaust ports, it still retains this.

[Sprocket]

Very much a 16valve man my self and that will be on an A series engine thank you very much

[pikey7]

Maybe I just don't get the 16v/VTEC conversions. What exactly is the challenge in being able to wield a torque wrench?

Although my challenge will be in using parts that have been used before, I want to have to think about using them in a way that they haven't been used before. That's what challenges a person; His intellect, not the size of his tool box.