3/5/7 angle valve jobs?

[Pumaracing]

I've asked a friend of mine to subscribe on here and add his wisdom to the forum. Hopefully you'll hear from him soon.

[DaveL485]

Pumaracing said:

DaveL485 said:

Pumaracing said:

If we can maintain a high gas speed just below and around the valve seat the kinetic energy of the incoming gas will resist this piston pressure and fill the cylinder better than might otherwise be the case. The conclusion this immediately leads us to is the the valve throat must not be too large or the gas speed will drop.

How does this rule alter when you introduce forced induction? We can keep the valve open a little longer, i'd assume, and use a bigger throat as the gas speed is artificially boosted?

Oh dear. The dreaded assumption - and the invariably incorrect conclusions that follow from it. Never AssUMe, and you know the rest.

The port gas speed doesn't alter a jot when an engine has forced induction. If the manifold pressure doubles then so does the gas density and therefore the mass flow and power. The speed stays the same.

Interesting. One must mull this over for a while before probably asking a load more questions lol

Pumaracing said:

DaveL485 said:

Would you alter the seat specifications from what has been talked about?

I don't change anything with forced induction engines, even very high boost ones, with the possible exception of my underwear.

Thankyou....my head is going from NA to Turbocharged so I shall be absorbing what you have said for when I get new valves made/fitted to cope with the heat.

[Brummmie]

stevieturbo said:

Yes, but do the 255cc heads have reduced guides ?

Even on my old "stg3" ported RV8 heads. They still left full bullet nose guides in place, because shortening them made no difference whatsoever.

Agreed, dont want them shortened, but just thinking less metal in the way and a nicer shape?

This is a set Dart's that are their 245cc CNC jobbies,

[anonymous-user]

Pumaracing said:

I've asked a friend of mine to subscribe on here and add his wisdom to the forum. Hopefully you'll hear from him soon.

He's is your "alter ego" isn't he Puma ??? ;-)

(the one who wears his Y-fronts on the outside of his trousers ! lol)

[David Vizard]

Hi all,

Mr. Puma Racing convinced me I should join this forum so --- here I am. Took a look through the stuff that Puma had written and I would have to say that he has taken a complex subject and put some very good ground rules in place. Stick with these and you won't go far wrong for all your basic needs.

I felt sure there was a place for a new book on porting and head flow/combustion characteristics in general but reading between the lines I suspect that the knowledge base out there is less than I even I had anticipated. Funny back when computers became all the rage there was a down slide in Auto tech in the popular press (books and magazine articles.) Sure they were out there but harder to find. I think we are now reaping the effects of this. The good news here is I will have a new porting book out about Jan/Feb 2012 which Mr. Puma has had a little more than just a passing helping hand in.

It's short notice but I will be at the Motorsports Show In Birmingham 12-15th Jan as a guest of Mountune Race Engines. Anyone want to swing by and visit or get an autograph is welcome. Also I am going to be doing a big Seminar at Swansea Metropolitan University next Sept. Check my web site at www.davidvizardseminars.com.

Just as a matter of reference just how many members does this site have???

Hope everybody has a great Christmas and Santa brings a brand new Boss 302 Mustang. (you gotta check that one out)

David Vizard

[dbv8]

[Pumaracing]

Clicking on Members then Directory you can see how many members are in each country although I can't see a final total anywhere. However just over 160,000 in the UK, 4000 in the USA - probably 180,000 total worldwide I'm estimating.

[Johnboy Mac]

dbv8 said:

Yep!

[Pumaracing]

dbv8 said:

Oi! Don't start f**king bowing to him. He's got a big enough ego as it is. He already thinks that when he dies and goes to heaven there'll be a special seat for him at God's right hand with "God's Chosen Engine Tuner" stencilled on the back.

You should see all the bol**ks he's written in the draft copy of this new porting book I'm trying to plough my way through and put him straight on before it gets printed

[Pumaracing]

Max_Torque said:

Pumaracing said:

I've asked a friend of mine to subscribe on here and add his wisdom to the forum. Hopefully you'll hear from him soon.

He's is your "alter ego" isn't he Puma ??? ;-)

(the one who wears his Y-fronts on the outside of his trousers ! lol)

Dunno whether he wears Y-fronts or boxers or for that matter on which side of his trousers but you can ask him yourself now

[phumy]

God has just emerged...

[stevieturbo]

I'm sure I speak for all when I say it's a privilege to have you here David, and thanks for taking the time to join.

As for members...there will be very many. But this is but a small section of a very large community.
Regular and active members in this specific section of the forum would be in the 3 figures I think.

People with your and Dave's experience are always very welcome though ! Even if some of the info can go over our heads lol.

[DaveL485]

David Vizard said:

Hi all

Hello! Pleasure to have you on board.

While you are both here, would you mind suggesting somewhere I can get a set of exhaust valves made please? The OE valves in the head im using won't put up with the stresses of forced induction.
There is no aftermarket option of any sort for the head, its custom application or nothing.

OP- sorry for the hijack but must take opportunity when it offers itself

[Megaflow]

Woah... The David Vizard.

[jeremyc]

David Vizard said:

Just as a matter of reference just how many members does this site have???

Well you were the 290,748th member to register on the forum. Many, many more are unregistered browsers, and I believe the site as a whole receives more than 4m unique visitors per month.

[Brummmie]

Yes, and he joined on my thread!!

But what about me bloody heads?

[stevieturbo]

What size exhaust valves are you using ? TFS fitted Inconel ones into mine.

You could also give the likes of Kurt Urban a shout, or Fraser at AES Engines.

http://kurturbanperformance.com/

http://www.aesracing.net/about.htm

[Pumaracing]

DaveL485 said:

Hello! Pleasure to have you on board.

While you are both here, would you mind suggesting somewhere I can get a set of exhaust valves made please? The OE valves in the head im using won't put up with the stresses of forced induction.

Who says?

[David Vizard]

Pumaracing said:

Oi! Don't start f**king bowing to him. He's got a big enough ego as it is. He already thinks that when he dies and goes to heaven there'll be a special seat for him at God's right hand with "God's Chosen Engine Tuner" stencilled on the back.

You should see all the bol**ks he's written in the draft copy of this new porting book I'm trying to plough my way through and put him straight on before it gets printed

I have known Mr.Pumaracing for over twenty years know and can tell you, smart though he may be, his humor can often be off in left field somewhere.
Right know I am trying to get him back to doing something that he is actually proving remarkably talented at (other than heads that is) - namely the writing of a scifi book. Read a few advance chapters so far and if I can get him to focus on it then I have a likely race car sponsor from all the money he will make when he sells the movie rights.

David Vizard

Next post, Mr. Pumaracing permitting, I will get onto something a little more technical!!

[David Vizard]

It's the holiday season and I have had quite a few of my old buddies in the UK call and ask how I'm doing and what I am up to theses days. Well I have now told the same hour long story (that's the short version) too a bunch of people and it occurred to me that maybe I should post something complete with pics and text of the short version of what I am currently doing in the motor sport field. It seems it would make a pretty decent article but I really don't know in what section I should post it to hit the most readers or what format it should take.
Let me have some input here and can anyone help as to the format. I envisage an article like a magazine deal but that does not seem to fit a regular posting format.
Suggestions welcome.
DV