Head choices
Turbo Mini Forums

Hi guys, been a little while since I have thought about my mini build due to work etc but keen to get back on the build. The shell is completely done and re-sprayed so I'm at the stage where I'm bolting things on etc.

I have a fresh bored 1275 to 1310, a decent straight cut box and proper LSD with semi helical gears, and 286 cam, I built the shell for some low level rallying/auto tests etc so the engine needs to make decent power but be reliable hence staying at 1310cc.

It's not going to be eligible for historic classes so I may as well do something decent with the head i.e. 7/8 port, I do have a 12g940(IIRC) and a Weber DCOE on long manifold already, but I was wondering if it is worth either going with a 7 port head, or a BMW K1200 conversion? I want to stick with carbs, I am using Nodiz/Megajolt, are there any major pro's and con's to either? p.s. it's a clubman front so should be room for carbs.

Cheers,
TC

www.topcatcustom.co.uk

I'd probably put a 7 port on, good gains for less hassle

It seems that to get decent gains and good drivability its best to go with EFI with a 7 port.

Out of all the 7 port heads I've seen the specialist components kit is one; if not the best. It's so nice and light as well. You can buy the complete kit with EFI and TB's so it's more or less bolt on.

Also with the 7 port everything is standard run of the mill A series bar the head. So you got a wide range of choice with cams and exhaust manifolds etc. With 8 port you need a special ground cam, longer push rods, different exhaust manifold etc.

Cant help with k head as it's not my sort of thing.

Out of all your options 7 port is probably the most straight foward in terms of building and setting up, it just depends how far you want to go really.

Edited by Pauly on 12th Oct, 2014.

Cool thanks, I was thinking by the time you add exhaust, cams, timing gear etc for the BMW head it would get up to a similar cost to the SC 7 port.

Is there scope to add more cam with a 7 port on twin Webers over a 5 port, i.e. 296 or something a bit more pokey than the classic 286?

www.topcatcustom.co.uk

No point going 7/8 port and sticking with carbs in my opinion.

I have a injected 7 port turbo. Drives like a modern car. Consistent AFR and better drivability.

I'm also building a race spec NA 7 port, that will be injected. Both using Specialist Componehts Billet head & Throttle bodies.
Prevously I had a piece manifolds (MED) 7 port with twin 40 DCOE's, running a 286. It was pretty poor below 3.5k. It made good power at 122bhp and sounded nice. I then swapped to AT Power throttle bodies. It was like night & day in terms of drivabilty and sounded equally impressive.

The SC head is far better in my opinion, but built for injection unlike the MED head.

I was planning K Head for my trackday car, but came to the conclusion 7 Port works out cheaper and easier.

In terms on camshaft I'll be using a 300degree custom race profile for the track, but the car will also be road legal and used regularly on the road. Made possible by EFi and no charge robbing from siamese ports on overlap. I'm hoping it should behave like a 286 in a 5 port.

Edited by alaskanow0 on 12th Oct, 2014.

Class C 3rd Place Avon 2011 14.18 @101mph

What about a RE13 cam, I have one but have not finished the engine yet so can not comment on drive ability.
John

“A turbo: exhaust gasses go into the turbocharger and spin it, witchcraft happens and you go faster.” - Jeremy Clarkson

I can confirm that the re13 loves revs!

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

I don't know about the RE13 cam, would it be something between a 286 and 296 in old money terms?!

I'm still hanging on to the last remaining months of my 20's at the moment, so should be embracing technology like injection but I still love carbs and a dissy (although I am going to use Nodiz or MJ on this one).

I'm hoping for something like 115bhp on this build, I was hoping it would be do-able with a 5 port but much easier with a 7, do you think this is realistic?

-

alaskanow0 Which MED head did you have- trackday or race spec? And with the big valves of the race spec is there no chance of cracking the heads as you could with a cast iron 5 port? I have to say the MED heads look appealing as they are ready to take Webers, and if lumpy below 3500rpm it's not the end of the world in competition use?

Edited by topcat on 14th Oct, 2014.

www.topcatcustom.co.uk

RE13
Timing: (Intake): 34.5/61.5 (Exhaust): 63.5/32.5
Nominal lobe lift: (Intake): 0.290" (Exhaust): 0.290"
Duration (Intake): 276 (Exhaust): 276

RE 83
duration 260
Valve timing IN OP 20 deg btdc closes 60 deg abdc
EX op 60 deg bbdc closes 20 deg atdc
Cam Lift .270

“A turbo: exhaust gasses go into the turbocharger and spin it, witchcraft happens and you go faster.” - Jeremy Clarkson