Head work (not the rude way)

[Simon13]

Can anyone recommend or know anywhere that can things such as
5 angle valve regrind
proper porting and flowing on a test bench
bigger valves
raising comp ratio
etc can be done for my 2.7 project

shame Griffen motorsport are dead now as i would of gone there!

[HartgeH27]

Si,

Cylinder Head Engineering in Fareham Hants - not a huge distance from you but the dogs m8

http://www.applegate.co.uk/company/06/02/607.htm

Fantastic work - buzz me sometime if you want to talk in detail.....

Iain

07810 650 395

[mason]

Hello Mate just a thought

Dont no if it would be of any help but all my cossie mates use H.T Howard in slough for all there head work and all report back very happy and its quite local

Mason

[Jordan]

Can anyone recommend or know anywhere that can things such as
5 angle valve regrind
proper porting and flowing on a test bench
bigger valves
raising comp ratio
etc can be done for my 2.7 project

shame Griffen motorsport are dead now as i would of gone there!

A 5 angle grind really is no better then a 3 on these heads. that said I still have a 5 angle job on mine.

Bigger valves really provide no gain on this motor at all. look up the math for calculating volume over a port size and you will see. +1mm is all you can do without putting new larger seats in. +1mm makes for less then 1% power gain. Not worth the time and money.

[HartgeH27]

Agree with Jordan - not much gains from 3 to 5 angle grind, the major gains are with the porting both sides and proper polishing.
BBTB + port + polish + 3 angle grind + decent cam + good 6 brancher is imho what is required. With this combination you will get maximum gains.
Headwork labour alone will be nothing less that Ԛ£750 as a guide but the difference is HUGE.

[Demlotcrew]

Jordan where are you getting your calculations from? 1mm bigger valves is alot! and im sure it would yeild more than 1% of power.

Bigger valves with five angle cuts will yeild more top end power on a 2v per cylinder engine. Simon needs a car thats sensible and an everyday driver thats why i would recommend he goes for a mild high lift cam with bigger valves and seat re-grind.

I will need to fish out a technical manual which shows how all these principles will help in top end performance and HP.

Andrew

[Ant]

if you get the std seats reground you'll find both valves are masked by the head casting and will require relieving to get any gains, downside of unmasking them is more material needs removing from the head reducing compression again.

all this Ԛ£Ã”šÃ‚£ for a NA slug, madness , and I know exactly what I'd use that 'Pina crank for ,
Whoooosh psssssssssst !

anything else is a waste unless its attached to a minty C2 with all the pedigree under the sun.

just my poinion though of course fellas

[bigkev]

does the extra cc's come from bigger bore and longer stroke ant if its bigger bore then the valves are already unmasked

[Ant]

its longer stroke Kev, the bore remains 84mm

these heads flow well anyways, little point in masses of porting work IMHO, the ports are large enough without opening them out, minor cleanup on the valve throat area and jobs a good -un

[Demlotcrew]

Ant are you talking about the valve reliefÔš's on the piston?

Andrew

[Ant]

no mate, look at the stock head with valves installed, you'll see the area I'm on about

[bigkev]

simon have you heard of velocity porting??

[chip-3door]

5 angle seats are an absolute waste of time IME on any engine, it really doesnt effect flow by any amount thats registerable on the rollers.

As above, the valve throats are the key to pretty much any head, and there is no point going bigger on the valves unless the throats are done accordingly.

Worth going wasited stem on them too IMHO

[bigkev]

are the valves not sodium filled gotta be carefull when waisting them

[chip-3door]

are the valves not sodium filled gotta be carefull when waisting them

I meant a nice set of 21-4N one piece replacements, wouldnt ever machine the standard ones.

[Simon13]

hmmm opinions!

turbo is great but not for this puppy. I might do one of those with an eta crank, seeing as there is nothing wrong with them! with the left over low comp pistons

back to heads. Theres defo some stuff worth getting done then like 3/5 valve angle and a good port and polish. So we established something!

[HartgeH27]

its longer stroke Kev, the bore remains 84mm

these heads flow well anyways, little point in masses of porting work IMHO, the ports are large enough without opening them out, minor cleanup on the valve throat area and jobs a good -un

IMHO Ant, the porting is not necessarily about opening up the ports and making them larger but it is porting to match inlet and exhaust to head to maximise good flow. Thats my non techy understanding of what is partly done to the Hartge/Alpina head ??? What you think ??

[Ant]

agreed Iain , port matching is a good plan for any engine.

Simon has a few things to work with now, I just dont want to see him throw Ԛ£Ã”šÃ‚£ away on head mods that look good on a spec sheet, but deliver nothing in the real world, no need for a monster cam either, just takes away all the bottom end gained with the stroker crank, pushed it back up the rpm range

M20 is like a Ford pinto, ports are already a bit large for the capacity , and the valve throat and seat are is where gains are to be had, no polishing required

M20 valves are one piece BTW, M42 has sodium filled exhaust valves but I think its the ony one to do so.

this is another case of horses for courses though, I hate peaky deliveries, always feel quick but fail to deliver any driving enjoyment for me, but I'm a lazy driver anyways

[Simon13]

this is another way i see it. Look at the differences between a 2.0ltr head and a 2.5.

Bigger valves by 2mm inlet and exhaust on 325i, but what i don't know is whether the ports either side are bigger. Different combustion chamber too

So the bottom end was bigger on a 2.5 so bmw made a head to suit it. And make use of the extra capacity. Plus the gains were a good 30bhp.
We know if u do it properly a good 2.7 can make 40bhp over a 2.5

Again 2.7 bigger bottom end, so what i need to find out is how to up grade my 2.5 head to optimize this bigger bottom end.

Surely to some extent i can use what bmw did for 2.0 to 2.5 for my 2.7

the fact it's a 2.7 will give me good low down grunt. A mildish cam will give good mid-range. And some well placed head work will give the top end and BHP.

This is the theory i'm working on, but obviously i need to research as much as poss before i go spending. As i only have 1 chance really

Am i making sense?!

Going to the bigger valve thing Jordan and everyone, say the valves are 10mm, thats 60mm overall for a 6pot lump. By increasing your valves to 11m will mean 66mm overall. So to me thats a 10% increase of air getting into the chamber. So from a common sense point of view it seems to make some sense. I know it's all good in theory but there must be something in it surely

[Simon13]

no one have any more thoughts on this?! or places to consider?

[MrDazzle]

S'not a 10% increase in area, it's a 21% increase.

[hoshy]

try steve at sbd motorsport... they're in chesingston very good bloke

[Kos]

simon mate, i'll get a few prices for you for different specs, who ever you use they gota be people who have done bmw heads before so the can tell you what gains they've got and what sort of cam they've used.

the guy i used has now gone back to cyprus, but i'll get in contact with him

as i said before, i got 25hp peak power increace from a head and cam with a bit of ecu trickery.

[Jordan]

Stock Intake 42mm 1384.74mmԚ²
+1mm Intake 43mm 1451.47mmԚ²
Increase +66.73mmԚ²

Stock Exhaust 36mm 1017.36mmԚ²
+1mm Exhaust 37mm 1074.67mmԚ²
Increase +57.31mmԚ²


Really not enough difference to make a damn bit of.. difference.

[chu346]

Well what about me?

I'm using a 2.0 head for my 2.7 I take it I should be using bigger valves. Can I use 325 valves?

I've been looking at http://www.cylinderheadshop.co.uk/ and http://www.pumaracing.co.uk/ to get my 2litre head done.

[Jordan]

the m20 320i and 325e use the same valves right? I'm pretty sure i valves do not fit in a 325e head, so I would assume it wouldn't work well for a 320i head either.

The ports are small on the 731 head anyways, valve size isn't a problem.

[Jordan]

Going to the bigger valve thing Jordan and everyone, say the valves are 10mm, thats 60mm overall for a 6pot lump. By increasing your valves to 11m will mean 66mm overall. So to me thats a 10% increase of air getting into the chamber. So from a common sense point of view it seems to make some sense. I know it's all good in theory but there must be something in it surely

While that all sounds fine and dandy to those that don't know whats going on.. the logic is seriously flawed.

+1mm intake valves result in a 4.6% increase in surface area at the edge of the valve.

+1mm is as large as the stock valve seats can be bored out to.

+2mm can be done with a bored valve seat seat, and new aftermarket valve seats.

I don't think you can get any larger then that in a 885 325i head without running into major clearance issues.

Also a 4.6% increase in outside surface area does NOT mean a 4.6% increase in flow. Ultimately the port entry and valve seat throat remain the same size.

I've seen flow bench numbers showing the difference between a 885 head casting, ported and polished to the max, with and without +1mm valves. The actual CFM difference was so small its laughable.

Don't take my word on it or anything though.

[Simon13]

I'm not going to take your word on it jordan, it's just good to read about other peoples experiences and opinions.

At high rpm's only half of the valve edge is touched isn't it?

I'm not thinking it will make a difference on it's own, but along with lots of other little things might make a decent difference.

Plus again, Alpina used bigger valves on their 2.7's. Must of done it for some reason or another?

[Kos]

hartge use biger inlet and exhaust valves

its a head ache getting it right aint it!!

[Simon13]

I haven't even started, just researching and preparing the bottom end which is happening as we speak, i get brain ache already

[Kos]

i'll get hartge specs for you, and alpina specs if you want??

[chu346]

I wouldn't mind the specs

[reggid]

I am looking at some head work on my M20B25 since my cam is severly worn and hence likely need rockers too. I am thinking

- shrick 272 cam with springs
- new rockers
- potentially new valves ( to be determined by further inspection)
- porting
- polish exhaust only
- bigger valves are not worth it from what i've seen
- Whats a 3 or 5 degree valve regrind actually mean?
- reseat valves and skim face.

how do you port match the inlet and exhaust? Do you send the headers or exhaust manifold (is it even worthwhile with the stock exhaust manifold) / inlet manifold with the head to the machinist?

what esle if any should i do should i do

[chu346]

- Whats a 3 or 5 degree valve regrind actually mean?

A 3 angle grind will give a smoother flow past the valve, and a 5 angle grind would be better still.

[Andy335Touring]

Yes, you send your inlet manifold off with the head and let them match it up