cylinder head
Turbo Mini Forums

been looking at different options recently, but a bit confused avonbar say you dont need to increase the exhaust ports but everone else does it so who's right any one had any experience with these heads or if avonbar could explain that would be great, been loooking at vmax heads they look good also what do you reckon cheers

I dont think many people enlarge the ports too much, just a decent gas flow. Mine certainly are pretty much the same size as standard as i think it gives better drivability, im sure you will loose a bit of low end pull and produce more lag with bigger ports!!!!

-MINI CLUBMAN 1380 TURBO-

i thought IPC owned max power????

Everyone knows that instructions only have to be read if the thing doesn't work....

ok who changed the thing under my name!!

Look at the exhaust manifold. If you open the ports in the head a lot, it WILL NOT fit the exhaust manifold ports.

This means enlarging the ports in the head a lot is a bad idea. Smoothen them out a bit, but don't enlargen much.

vmax also modify the manifold as well though,
and really whoever changed the thing under my name please change it back, must be an admin otherwise sumone guessed my random password

Ha ha ha ha ha ha ha!!!

You can't change that yourself, one of the mods will have done it!!

I vote for it to stay but there you go!!!!!!

Vmax may well open out the manifold at either end, but it will only be opened out in the middle of the branches with magic, or extrude honing!

I personally favour small inlet and exhaust ports - mine are slightly larger than stock on the inlet and the exhaust - but each to their own.

Edit: a bit of clarification - when i say my ports are slightly larger than stock, I'm reffering to the straight sections of the port; All the ports are obviously modified around the 'bend' on both inlet and exhaust, this being the most restrictive part of the whole cylinder head by far (discounting the valves clever clogs)

Edited by turbodave16v on 21st Feb, 2005.

cheers tom

% increase in flow is gained most in the area from valve to straight section of port , have a look at a cut away in vizzard its unreal how much you can remove !!!

Everyone knows that instructions only have to be read if the thing doesn't work....

so the avonbar one looks better to me vmax go up to a 35 chamber though i take it this will lower the comp ratio quite a bit or am i wrong?

I just got a vmax head of ebay,a bit cheaper than the one on there at the mo just wonderd which one is best spec

mine
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?Vie...me=STRK:MEWN:IT

the other one

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?Vie...4528692606&rd=1

Edited by Dangerous on 21st Feb, 2005.

Metro turbo weekend driver,Mini turbo in the making again!

The one you bought has the Gp "A" size valves with the 31mm exhaust, as opposed to the standard 29mm. Some people say there is no advantage using a larger exhaust valve on a Turbo motor, but if that's true then why did the Gp "A" motors use a larger valve ? was it purely to give more surface area to dissapate heat ? possibly.................
I am curently using a head with a larger exhaust valve, and from "seat of the pants testing" the motor is going well, with a noticable improvement over my old 29/36 head. I did change the cam at the same time though so i think it could be a combination of the two. As usual i have no rolling road data to back this up, just gut feeling.
Saying that, there are plenty of people running standard exhaust valves with good results, but i can't see a larger one doing any harm.

One thing to do, even when keeping the exhaust ports totally or almost standard, is to match, or make slightly larger the exhaust manifold runners where it meets the head face. I found even on a standard head that the manifold overlapped and blocked slightly the exhaust port on the head face. This was worst on the outer two ports. You could see where the carbon had built up on the manifold face, 1/8" or so.

Phil.

Edited by Turbo Phil on 21st Feb, 2005.

WWW.TURBO-MINI.COM

theres not much point in making the ports in the head massive , i open out the head to be slightly smaller than the gasket and then match the manifold to this size , the manifold is smaller inside but the longer the distance you have to change shape/size to less restrictive it should be , always check the exhaust manifold as they can be cast a long way out
where the manifold meets the turbo round off the dividers profile to reduce cracking
my opinion is the 32 mm ex valve is the opimum size for ex flow combined with a 34 -36 inlet
this is based on experience ,compatabillity for unleaded inserts, flow bench, and rolling road testing

ok got bored and realised i need a new subframe so a rebuild is on the way, thinking of avonbar for the bottom end and vmax for the head

why not vmax for everything~?

alex

AlexF

dunno avonbar seem quite good and not badly priced theres no prices on vmax website for bottom end

Then I would take time to find out. I've just bought a head from Vmax and it does look the the biz. Would be interested to know myself if Vmax can sort the rest of my engine.

P.M. sent Stuart.

You are probably even younger then I am( based on the fact that you read MaxPower), but when I was young, we had this great little device called telephone. It was like magic. You could call people and talk to them, just like they were right beside you. If there was a question about something, you could dial a number (almost everyone had their own) and talk to people. This Internet (is it) sort of killed the telephone. Pity that!

lol@Vegard !

WWW.TURBO-MINI.COM

i dont read max power!

but am probably younger lol!

I find the phone much better than writing on here for find out about services and product to V....

LOL

alex

AlexF

I was going to go for a moorspeed one because i was taken in by the info they give, but i would concider an Avonbar because i heard he's going to give turbominis.co.uk discount somewhere on here

Previous Engine: 1040cc Morespeed engine, 1275 turbo head T2 Turbo Mirage Manifolds Megajolt
Previous engine: STD metro turbo, megajolt
Drives: 399bananahp (flywheel) Honda Civic Vtec b18c4 T28 Turbo 1968 Mini

Megajolt maps to download: http://www.jamesfawcett.co.uk/cms/index.ph...&gid=3&Itemid=3