Turbo Heads

I have been looking at taking some metal away on the exhaust side .The head has a 31.5mm diameter outlet and the std mani is 34 ..............and that would bring it closer to the inlet size at 35 .Might not sound too much of a diff but it equates to 1.3cm .
There is also a bulge that intrudes ,I can't see any reason for it other than a bit of strength below where the cooling channels run up to the gasket

Be careful not to take too much away at that point.
Not sure if the heads are designed in a similar way but when i had a 'dini' head done it sprang a leak in one of the ports after a few thousand miles of running!

Hmmmmm. I don't know a lot but I'm pretty sure that attempting to gas flow a head in a super/turbo charged engine is pretty pointless. A completely different set of rules to an atmo when you are trying to encourage the gas to flow more easily.
If you want more flow just boost it more. It will have a lot more effect.

Surely though you will only be able to acheive so much through boost.
If there is a given restriction in the line then this will limit the flow whatever the boost!?
This has been talked about before.(not sure how much the heads restict though).

My old 'dini' atmo had a flowed head,lightened flywheel and RS2000 carb.This gave a genuine 90 BHP at the wheels,(Std 93 at fly),so the headwork proved worthwhile on this engine!!

I think it will help a bit,a restiction's a restriction .If you're constipated pushing harder wont help ,but if your a###hole was bigger

lee, i'm with you on this on "in theory".
as rupert says, atmo and turbo are completely differtent.
On a turbo I also think it is pointless to flow the inlet side.
But on the exhaust side surely you want the gasses out of the port ASAP and to hit the turbo AF(ast)AP, afterwich you just want rid of them AFAP.

There's also the reverse flow from exhaust on the overlap

lee, i'm with you on this on "in theory".
as rupert says, atmo and turbo are completely differtent.
On a turbo I also think it is pointless to flow the inlet side.
But on the exhaust side surely you want the gasses out of the port ASAP and to hit the turbo AF(ast)AP, afterwich you just want rid of them AFAP.

Nope, it is completely the opposite.

Any restriction on an atmo (think of it as one bar atmospheric) is doubled when you are running double the air (2 bar atmospheric), so it is doubly important.

If you can make 150bhp n/a, then with a bar of boost (all things being equal double the airflow and double the matched fueling too), then best case scenario would be 300bhp. But this will only happen if you keep everything equal. Why settle for less?

lee, i'm with you on this on "in theory".
as rupert says, atmo and turbo are completely differtent.
On a turbo I also think it is pointless to flow the inlet side.
But on the exhaust side surely you want the gasses out of the port ASAP and to hit the turbo AF(ast)AP, afterwich you just want rid of them AFAP.

toaster, what would he know !

thats that theory blown away.

Stick to wiring Mr T

Simple way of looking at it is compare any 8v turbo engine and power per boost to a 16v variant...

I can not see why please are saying it is pointless. I had the head on my renault 5 turbo ported and polished and it made a world of difference. About 15 bhp weather a car is turbo or n/a does not matter the result is the same just in different digrees, if anything it should make a bigger difference on a turbo because you are talking about bigger pressures and the quicker you can get thoughs pressures out the better.

soory should have said people not please.

is pressure directly proportionate to flowed volume?
so if you add 50% for pressure, do you get 50% more volume of air in/out?

i think i need to read wikipedia a bit more

You don't wanna trust that Wiki stuff , just look at the external links info for the PRV


Better to get this ...........covers everything and more .............
He does say that you should only clean off the ' Dingle Berries ' and the area under the valve seat .A good old smooth and light polish .I think I may still increase the size though
All other work on the seat itself but that gets a bit precise .


http://www.amazon.co.uk/Forced-Inductio ... 876&sr=8-1