Rover V8 cylinder head porting advice.

[kiwicar]

"its interesting that many of you say that I dont need to port match the inlet with the inlet gasket, is that correct? "
Hi
certainly what I am saying is not that it is not necessary, what I am saying is that on rover heads it is counter productive to getting the best flow out of them.
As for best tool, a die grinder is ideal, a drill with a flexable extension drive is pretty good, a drill with a long shaft bur is good but a bit clumsey, never used a dremmel for this as I think it would burn it out, it would also be dead slow. I use a drill and a long shank bur for the stuff I have done on the chevy, then verious flap wheels cylingrical sanding thingys and hand tools.
Best rgards
Mike

[unstable load]

The bit that "ramps up" to the guide hole is curious to me.
Would anything be gained by removing that ramp and bullet
profiling the part of the guide that protrudes into the head?
Looking down on it through the seat, it also looks really rough
on the one side, so doing away with it and bulletting the valve
guide should tidy things up nicely there.

Am I on track or missing the point here??

[Eliot]

You would end up with an even shorter valve guide - and dont forget that the valve stem still sticks out of the guide, so I would say there's little to be gained from removing any more material.
If you look at the heads other people have done, I would say my dad's version has gone quite far in terms of reducing that area.

[sidecar]

I'm not trying start a bun fight here but I really don't get why the manifold should not be port matched to the heads. My heads are I guess what most people would call stage III, they have the Real Steel DW500 valves and the tracks have been gas flowed which included opening up the inlets at the inlet gasket face. I run an Eddy Performer manifold and the ports in it are quite small, the manifold would create a huge step at the inlet gasket face if it had not been opened up to match the heads. Without doing this it seems to me that the work done on the heads is sort of a waste. V8 Developments did my heads and they were of the opinion that the manifold would benefit from being port matched.

[kokkolanpoika]

I have seen an chevy 350 engine. It has got some alloy heads witch inlet track has been ported far too big, gas speed is to low. The engine builder who build this engine (porting job already done). First he made a custom inlet gasket, same size as head/manifold ports and they but that engine on dyno, it will make approx 550hp.. Then they realise something is wrong. He take manifold off, take a std size big bore inlet gasket, smaller than tracks. Engine made over 40hp more with same dyno.
It is not neccesary to port match, but its advisable. And it is very hard to see all those sharp corners in STD RV8 efi manifold..

[unstable load]

Eliot,
OK, my apologies, I just had another look at your Dad's head and I see now that the guide is already in place which answers my question.

[kiwicar]

I have seen an chevy 350 engine. It has got some alloy heads witch inlet track has been ported far too big, gas speed is to low. The engine builder who build this engine (porting job already done). First he made a custom inlet gasket, same size as head/manifold ports and they but that engine on dyno, it will make approx 550hp.. Then they realise something is wrong. He take manifold off, take a std size big bore inlet gasket, smaller than tracks. Engine made over 40hp more with same dyno.
It is not neccesary to port match, but its advisable. And it is very hard to see all those sharp corners in STD RV8 efi manifold..

this is even more the case with the rover head, by all means match the port to the manifold if you feal you must but do not match either to the gasket do it with templates and take the absolute minimum of metal off either. You are aiming at a constant taper of around 7% area from the end of the bowel area to the open air (or plenum) the key word here being constant
Best regards
Mike

[sidecar]

I still don't get it..."It not neccessary but advisable".

Also how come all of the stage III heads tha I've seen have had the inlet opened out to be as large as possible?

[Wotland]

each head porting guru seems have his own recipe.
I have huge ports on mines, removed valve guide boss, etc.... Job done by Paul Goodenough when he worked at NCK/TVR : http://www.v8forum.co.uk/forum/viewtopi ... ght=tuscan

[cammmy]

As Mike has said, you want a constant narrowing of the port from the entry of the manifold runner to the valve area. This builds up the velocity of the air and helps cylinder VE.

If you open up the manifold and the port face to match the gasket, you will end up with a taper in the manifold runner and then an expansion where the manifold meets the head and then a taper again from the port face to the valve. Not good for VE as the velocity slows down when it enters the port.

Hope that makes sense

[kiwicar]

Hi
There are a number of reasons for opening the ports up to the gasket,
1/ "It has always been done that way"
2/ "It is what the customer expects"
3/ "It Obviously is correct"
You don't do it for the reason below.

4/ "It is what produces best results"
Because 95% of the time it doesn't

If you are buying "stage three" and had 2 sets in front of you, one opened up as far as they would go at the gasket face and one opened up very little, which would you buy? Come on honestly you would expect to see "really big ports"? I bet you do because you will be judging them on criteria 1 and 3, the head porter will be operating on 1 and 2 so when you by "stage 3 heads" that is what you get, in this case number 4 does not get a look in because your average head porter wants to sell heads.
If you don't want to accept this as an argument then fine, but think for a minute who decides which tyre tread patterns you get to buy, it is not the R&D department it is the Marketing department!
Best regards
Mike

[Blown v8]

When I port matched my inlet manifold to the head,I did notice my blower pressure had dropped,surely this is because the air "flows" better ? The same amount of air is flowing,but without restriction.
Or am I missing something ?

[sidecar]

As Mike has said, you want a constant narrowing of the port from the entry of the manifold runner to the valve area. This builds up the velocity of the air and helps cylinder VE.

If you open up the manifold and the port face to match the gasket, you will end up with a taper in the manifold runner and then an expansion where the manifold meets the head and then a taper again from the port face to the valve. Not good for VE as the velocity slows down when it enters the port.

Hope that makes sense

Yes that does make sense and I can see that a sort of bulge in the track would not be very good, however I'm not sure that a step in it would be much good either which is what you will get if you leave the manifold un- matched. I guess if you are really careful it 'might' be possible to open up the manifold and at the same time maintain some sort of taper all the way from teh carb down to the valve.

[kiwicar]

When I port matched my inlet manifold to the head,I did notice my blower pressure had dropped,surely this is because the air "flows" better ? The same amount of air is flowing,but without restriction.
Or am I missing something ?

Again there still seems to be a huge amount of confusion what is being said here.
The original post was about matching the inlet manifold to the heads by matching both to the gasket This causes a reverse taper in the port and is generally bad for overall flow and is to be avoided where ever possable.
On 95% of heads matching the inlet to the ports can be done, and if done carefully removing the minimum of material can show some small gains, however it is often the case that under 80% of circumstances it results in no measurable power gain as there are other things going on here than absolute flow numbers. Power comes from an engine not a flow bench bigger flow numbers do not always result in more power. Often it is not worth the effort on anything other than full race engine and it most certainly does not always result in more power.
A supercharged engine can have very different port flow charicteristics to a normally aspirated engine, what will increase flow and power on one may do the reverse on the other. Hogging out the ports on a blown engine may well result in a lower boost measurment on your boost gauge, weather this is due to better flow through the engine or just better flow into the inlet manifold and away from your measurment point would require a lot of work to find out, also You may have changed the flow mode from turbulent to laminer around the measurment point and that alone would give you a different reading. You may have changed the flow mode through the whole head and gained a lot of flow, have you timmed the car between two points befor and after the change and seen better performance? Yes it may be offering less back pressure but it may not.
Best regards
Mike

[sidecar]

Hi
There are a number of reasons for opening the ports up to the gasket,
1/ "It has always been done that way"
2/ "It is what the customer expects"
3/ "It Obviously is correct"
You don't do it for the reason below.

4/ "It is what produces best results"
Because 95% of the time it doesn't

If you are buying "stage three" and had 2 sets in front of you, one opened up as far as they would go at the gasket face and one opened up very little, which would you buy? Come on honestly you would expect to see "really big ports"? I bet you do because you will be judging them on criteria 1 and 3, the head porter will be operating on 1 and 2 so when you by "stage 3 heads" that is what you get, in this case number 4 does not get a look in because your average head porter wants to sell heads.
If you don't want to accept this as an argument then fine, but think for a minute who decides which tyre tread patterns you get to buy, it is not the R&D department it is the Marketing department!
Best regards
Mike

Hi Mike,

I understand what marketing is all about so yes I do accept what you are saying as a valid argument.

I can also see that opening up the ports is probably a bad thing if the valves are standard and the engine is basically standard. The taper from the inlet down to the valve would be too steep and there would be the 'bulge' at the joint between the manifold and the heads.

Regards,

Pete