36 replies to this topic

[maph2]

dont bother with a 7 port, u still have stupid siameese ports on the exhaust. If ur willing to spend money on a 'different' head go for a 8 port.

As for getting engines from minisport... i wouldnt, but its your choice.

the main issue with the siamesed ports is on the inlet side i thought - (charge robbing etc), which is why the 1 port per cylinder is a performance gain. appreciated that porper crossflow is the best but i think 7ports make good power for the price (unless you go turbo/supercharger) compared to the 8port which is mega money.

go 7port and fuel inject for power and reliability if you are sticking with a series. if you fuel inject using the jenvey "narrow" throttle bodies and short trumpets, it will fit under a standard bonnet

[alexcrosse]

you cant moan about having to change a cam on an engine your building up yourself! lmao. And with a 1430 you need cooper s rods n e way, so thats all normal. So rubbish, 7 port is just as much hassle as 8 on a 1430 self build. The only thing you would have to actually spend more money on if putting a 8 port head on a 1430 rather than a 7 is longer push rods which cost pennies!

+ you do get less power because of the siameased exhaust ports, thats why you can get so much more power out of Xflow ford engines, because there much more free flowing.

you can also fit a 8 port with throttle bodies under a bonnet, not that i ever would, the power you would loose is stupid, like using a swan neck manifold on a weber.

Edited by alexcrosse, 06 November 2007 - 12:31 PM.

[Jammy]

But if your taking advantage of the increase in power the 8 port would give you then you'd need to upgrade certain components, ie X-pin diff, at least a grey diaphragm.

Plus you then have the cost of two 8 port camshafts (one being relatively more expensive than a normal A series camshaft anyway), and little things like cam pulleys, etc. Then there are fewer people around that actually know how to properly tune an 8 port.

[The Matt]

you cant moan about having to change a cam on an engine your building up yourself! lmao. And with a 1430 you need cooper s rods n e way, so thats all normal. So rubbish, 7 port is just as much hassle as 8 on a 1430 self build. The only thing you would have to actually spend more money on if putting a 8 port head on a 1430 rather than a 7 is longer push rods which cost pennies!

I wasn't saying that physically changing a cam was a problem, that's not the difficult bit is it!

I was thinking more along the lines of having more cam options, having more exhaust options, cams are cheaper, manifolds are cheaper and more readily available, they're all tried and tested, you can get stuff second hand, you can use the same rocker gear, you can...........

Actually, you seem to know it all, dunno why I bothered to offer an opinion to someone that dared to be different to yours!!!

IMO the main issue (as said above) is the distribution of the inlet charge on a siamese port system. This is exaggerated on anything but split webers or twin SUs, the way the fuel flows into the outer two cylinders is NEVER the same as the way it flows into the two inner cylinders. The centre exhaust port still gets shared across 2 cylinders on a 7 port head, so what! As for building an 8 port over a 7 port, of course you're going to have to do extra work for the 8 port build, the valves don't even open in the same order IIRC. I think they are arranged inlet, exhaust, inlet, exhaust, inlet, exhaust, inlet, exhaust, not exhaust, inlet, inlet, exhaust, exhaust, inlet, inlet, exhaust. Building a 1430 is nothing special, there are hundreds of them around, adding an 8 port head into the equation would make it a far more complex/different build. Adding a ready made 7 port head is a bolt on option!

[pmorrise]

I seemed to have open a can of worms here.... just to wind things back a bit.... this is my first complete engine build, so I was thinking about keeping it as simple as possible...... so it looks like it will be a stage 5 head on the 1430cc block which I hope is good for around 125bhp, thats quick enough for me.

[neil_g]

check that so called "stage 5" is not leaded fuel only.

[Jammy]

Ignoring whats been said already...

Get yourself the Mini Builder DVD, where they fully build a 1380, that plus maybe a workshop manual and the earlier Haynes (the earlier one has a MUCH better gearbox rebuild guide) should help you out no end if your building your first engine. Also, 'How to Modify the A Series Engine' by David Vizard contains just about all the information any novice engine builder will ever need to decide on an engine spec.

Believe me, after you've drove a few cars with a range of engines (ill-tuned 1275, Stage 1 998 and full race 1425), you start ignoring bhp figures and begin to think about the general make up of the engine and how well it suits the type of driving you'll be doing with it. Theres no point in building something with 130bhp if it only has that power at the top end and you spend all day driving around town, or if you have loads of power and no torque, and you spend all day on a motorway...

If you want to let us know what sort of driving you'll be doing with this engine then we could help you out with the spec. I believe the 1380 that they build on the DVD makes for a great fast road engine, and its not an expensive build. Do that with a good engine builder doing the machining and you can't go wrong.

[pmorrise]

If you want to let us know what sort of driving you'll be doing

I'm going to be running 10" rims and a 4 speed close ratio box, I guess what I'm after is a "rally" type engine if that makes sense. so it has to have good power throughout the rev range, not just top end.

Edited by pmorrise, 06 November 2007 - 02:40 PM.

[maph2]

Ignoring whats been said already...

Get yourself the Mini Builder DVD, where they fully build a 1380, that plus maybe a workshop manual and the earlier Haynes (the earlier one has a MUCH better gearbox rebuild guide) should help you out no end if your building your first engine. Also, 'How to Modify the A Series Engine' by David Vizard contains just about all the information any novice engine builder will ever need to decide on an engine spec.

Believe me, after you've drove a few cars with a range of engines (ill-tuned 1275, Stage 1 998 and full race 1425), you start ignoring bhp figures and begin to think about the general make up of the engine and how well it suits the type of driving you'll be doing with it. Theres no point in building something with 130bhp if it only has that power at the top end and you spend all day driving around town, or if you have loads of power and no torque, and you spend all day on a motorway...

If you want to let us know what sort of driving you'll be doing with this engine then we could help you out with the spec. I believe the 1380 that they build on the DVD makes for a great fast road engine, and its not an expensive build. Do that with a good engine builder doing the machining and you can't go wrong.

wise words /\/\ - listen to the doctor

[Jammy]

If you want to let us know what sort of driving you'll be doing

I'm going to be running 10" rims and a 4 speed close ratio box, I guess what I'm after is a "rally" type engine if that makes sense. so it has to have good power throughout the rev range, not just top end.

Ok, well without trying to sound condescending or anything, is it going to be used for rally driving? Or a daily trip to uni, weekend play thing, motorway commuter, etc.

I do though, appaulade your decision to go with 10" rims!

[pmorrise]

its going to be used as a weekend play toy..... have a standard '94 cooper as a daily run about, oh and a Volvo V50 for the wife.

so this is not a practical engine, its just a fun engine, it'll probably see 2000 miles a year tops !

As for the 10's, yeah, I had some more advice on the wheels and I think 6x10's with 165x70x10 yoko A032-R tyres is the way to go with AVO coil overs and KAD anit roll bars front and rear (and the usual bush kits and camber bars etc)

[Jammy]

Ah ok. If your doing 2k a year then at least the engine should last 3-4 years at least, if your going for an all out performance engine.

I agree with your size of wheels and tyres, personally though I'd start driving it before deciding whether I wanted roll bars. On my last mini that had fully adjustable suspension all setup using lasers and stuff I don't think I would have need anti-roll bars, at least not for road driving anyway.

[alexcrosse]

But if your taking advantage of the increase in power the 8 port would give you then you'd need to upgrade certain components, ie X-pin diff, at least a grey diaphragm.

Plus you then have the cost of two 8 port camshafts (one being relatively more expensive than a normal A series camshaft anyway), and little things like cam pulleys, etc. Then there are fewer people around that actually know how to properly tune an 8 port.

8 ports rnt 16v mate, ur gettin mixed up, im on about arden, 1 cam. If ur lookin to run a 1430 ud hav a xpin dif, grey is no more expensive than orange which ud b runnin on a 1430 as u hav before jammy! lol. U need cooper s rods for a 8 port, ud have them on a 1430 because of the crank. So all you need is the head and cam.
Granted jammy, 16v does need all the pullys, 2 cams etc like you say, and cost alot more mular!

[pmorrise]

yeah, I was hoping to get a few years out of the engine once built... I'll be posting a "project thread" up on the forum so everyone can keep a watch on what I'm up to in a month or so......

But I think I'll go for a 1430cc with a stage 4 or 5 head (depending what runs unleaded) and a single 45 weber, that will be a good first engine build and somthing that will be a lot better then the standard cooper I have now.


I'm off to Amazon now to order all that reading material.....

[neil_g]

youre looking at a marginal performance difference between 7 and 8 ports imo.