[phpBB Debug] PHP Warning: in file [ROOT]/includes/bbcode.php on line 483: preg_replace(): The /e modifier is no longer supported, use preg_replace_callback instead [phpBB Debug] PHP Warning: in file [ROOT]/includes/bbcode.php on line 483: preg_replace(): The /e modifier is no longer supported, use preg_replace_callback instead [phpBB Debug] PHP Warning: in file [ROOT]/includes/bbcode.php on line 483: preg_replace(): The /e modifier is no longer supported, use preg_replace_callback instead [phpBB Debug] PHP Warning: in file [ROOT]/includes/bbcode.php on line 483: preg_replace(): The /e modifier is no longer supported, use preg_replace_callback instead [phpBB Debug] PHP Warning: in file [ROOT]/includes/bbcode.php on line 483: preg_replace(): The /e modifier is no longer supported, use preg_replace_callback instead [phpBB Debug] PHP Warning: in file [ROOT]/includes/bbcode.php on line 483: preg_replace(): The /e modifier is no longer supported, use preg_replace_callback instead [phpBB Debug] PHP Warning: in file [ROOT]/includes/bbcode.php on line 483: preg_replace(): The /e modifier is no longer supported, use preg_replace_callback instead [phpBB Debug] PHP Warning: in file [ROOT]/includes/bbcode.php on line 483: preg_replace(): The /e modifier is no longer supported, use preg_replace_callback instead [phpBB Debug] PHP Warning: in file [ROOT]/includes/bbcode.php on line 483: preg_replace(): The /e modifier is no longer supported, use preg_replace_callback instead [phpBB Debug] PHP Warning: in file [ROOT]/includes/bbcode.php on line 483: preg_replace(): The /e modifier is no longer supported, use preg_replace_callback instead [phpBB Debug] PHP Warning: in file [ROOT]/includes/bbcode.php on line 483: preg_replace(): The /e modifier is no longer supported, use preg_replace_callback instead [phpBB Debug] PHP Warning: in file [ROOT]/includes/bbcode.php on line 483: preg_replace(): The /e modifier is no longer supported, use preg_replace_callback instead [phpBB Debug] PHP Warning: in file [ROOT]/includes/bbcode.php on line 483: preg_replace(): The /e modifier is no longer supported, use preg_replace_callback instead [phpBB Debug] PHP Warning: in file [ROOT]/includes/bbcode.php on line 483: preg_replace(): The /e modifier is no longer supported, use preg_replace_callback instead [phpBB Debug] PHP Warning: in file [ROOT]/includes/bbcode.php on line 483: preg_replace(): The /e modifier is no longer supported, use preg_replace_callback instead [phpBB Debug] PHP Warning: in file [ROOT]/includes/bbcode.php on line 483: preg_replace(): The /e modifier is no longer supported, use preg_replace_callback instead [phpBB Debug] PHP Warning: in file [ROOT]/includes/bbcode.php on line 483: preg_replace(): The /e modifier is no longer supported, use preg_replace_callback instead [phpBB Debug] PHP Warning: in file [ROOT]/includes/bbcode.php on line 483: preg_replace(): The /e modifier is no longer supported, use preg_replace_callback instead [phpBB Debug] PHP Warning: in file [ROOT]/includes/bbcode.php on line 483: preg_replace(): The /e modifier is no longer supported, use preg_replace_callback instead [phpBB Debug] PHP Warning: in file [ROOT]/includes/bbcode.php on line 483: preg_replace(): The /e modifier is no longer supported, use preg_replace_callback instead [phpBB Debug] PHP Warning: in file [ROOT]/includes/bbcode.php on line 483: preg_replace(): The /e modifier is no longer supported, use preg_replace_callback instead [phpBB Debug] PHP Warning: in file [ROOT]/includes/bbcode.php on line 483: preg_replace(): The /e modifier is no longer supported, use preg_replace_callback instead [phpBB Debug] PHP Warning: in file [ROOT]/includes/bbcode.php on line 483: preg_replace(): The /e modifier is no longer supported, use preg_replace_callback instead [phpBB Debug] PHP Warning: in file [ROOT]/includes/bbcode.php on line 483: preg_replace(): The /e modifier is no longer supported, use preg_replace_callback instead [phpBB Debug] PHP Warning: in file [ROOT]/includes/bbcode.php on line 483: preg_replace(): The /e modifier is no longer supported, use preg_replace_callback instead [phpBB Debug] PHP Warning: in file [ROOT]/includes/bbcode.php on line 483: preg_replace(): The /e modifier is no longer supported, use preg_replace_callback instead [phpBB Debug] PHP Warning: in file [ROOT]/includes/bbcode.php on line 112: preg_replace(): The /e modifier is no longer supported, use preg_replace_callback instead [phpBB Debug] PHP Warning: in file [ROOT]/includes/bbcode.php on line 112: preg_replace(): The /e modifier is no longer supported, use preg_replace_callback instead [phpBB Debug] PHP Warning: in file [ROOT]/includes/bbcode.php on line 112: preg_replace(): The /e modifier is no longer supported, use preg_replace_callback instead [phpBB Debug] PHP Warning: in file [ROOT]/includes/bbcode.php on line 112: preg_replace(): The /e modifier is no longer supported, use preg_replace_callback instead [phpBB Debug] PHP Warning: in file [ROOT]/includes/functions.php on line 4752: Cannot modify header information - headers already sent by (output started at [ROOT]/includes/functions.php:3887) [phpBB Debug] PHP Warning: in file [ROOT]/includes/functions.php on line 4754: Cannot modify header information - headers already sent by (output started at [ROOT]/includes/functions.php:3887) [phpBB Debug] PHP Warning: in file [ROOT]/includes/functions.php on line 4755: Cannot modify header information - headers already sent by (output started at [ROOT]/includes/functions.php:3887) [phpBB Debug] PHP Warning: in file [ROOT]/includes/functions.php on line 4756: Cannot modify header information - headers already sent by (output started at [ROOT]/includes/functions.php:3887) RS Motorsport :: Classic Speed Restored • View topic - Pinto Cylinder head development - Valve sizes
Based on some reading I have been doing recently it appears that pinto head has inlet valves which are too small for maximum power even when using the group 1 valve sizes of 1.75 inch.
I know this is for an American V8 but the following excel spreadsheet is still valid in my opinion and based on years of cylinder head development.
If you change the bore size to 3.57 at the top of the spreadsheet it will re-calculate the maximum valve and throat sizes.
I think that the Pinto is canted at 7 degrees so this would indicate that the valve size could possibly go to 1.9 inches. I know that this would be impossible to fit in a standard pinto head but still food for thought. The exhaust valve would have to be left at standard size to come even close to this and would require a lot of changes to the cam timing to make the most of it.
Speed talk is definitely a good way to spend an hour or two, there is alsways something new to keep you interested.
I am planning a bit of experimentation on my pinto in the near future but finances are always an issue, with a house extension, two children and numerous other things going on. I am trying to decide what the best cource of action to take to get the max from my engine without spending the world. I will be buying big valves but want to make the best choice hence the previous posts. I am also looking at welding both combustion chambers and ports so am looking at ways of doing that. I think that the american V8s are the ones to keep a watch on as they seem to be the only ones developing 2valve per cylinder engines any more. I am also trying to do some simulations on the pinto to see what improvements can be made to cam timing and induction/ exhaust lengths.
when you look at realy big valves, IE bigger the what is concidered normal, you need to make sure there is enough metal in the head to accomodate both the valves and porting needed.
Getting few and far between but would like to know what I have to work with first. I dont think I have compared the two side by side, only going from reports such as..
'The inlet port on an injection cylinder head is a lot higher than the standard cylinder head because of the shape required to site the injectors on a road car, so we clean out the bottom of the port with a die grinder to allow an alloy stuffer, designed in house, to blend in and locate without thin edges. The cylinder head is then drilled and tapped to accommodate two 1/4 U.N.C. Allen bolts to hold each stuffer.
We then locate the cylinder head to a jig and the valve guide holes and valve seats are machined at precise angles and locations.
The cylinder head is now jigged and the inlet port is drilled and bored in its new position and angle.
The inlet manifold stud holes are now filled in and re-drilled and tapped to 0.2" further up the cylinder head. This enables the standard two litre inlet manifold gasket and manifold shape to fit the modified parts.
One of the guys on the turbosport forum suggested using mig brazing to fill the floor of the pinto port to improve short side radius rather than using epoxy filler. I was thinking of taking this one stop further and using mig brazing to fill in the combustion chamber and re-shape it as per David Vizards book and the latest V8 heads from the US (Bow tie style chambers)
After a bit of research I found that mig brazing has a working temperature of approx 1000 degrees rather than 1600 degrees for mig welding. Also the melting temperature of the braze is around 800 degrees. While this is lower than the cast iron it is much higher than the melting temperature of aluminium (630 degrees) so should not melt during combustion.
Hopefully this would minimize the banana effect you talk about as this cannot be good with a camshaft running in the head.
Hi Tom
Have a read of the older thread on CNC pinto heads
chanber welding is all sorts of fun, we did it 5 or 6 times
The only tip i can give you is get all the welding (not brazing) done at once, pay attention to the valve seats, if you are not going to run hardened inserts get them welded up too as they will be too deep in the head to get correct stem height
To minimize the warping weld one chamber per day and one port per day making it an 8 day job for someone
The good thing about all this is that the competent place that does the welding will also be able to straighten it all after the event, once the cam fits all the other machining can be done
I personally think you will gain more by changing the chamber shape than you will by raising the inlet ports, you can flow stupid amounts in but you should wory more about what happens once it is in and then getting it out
Some very nice pics there and useful dimensions for machining a port.
I am still at the investigation phase. Things going a bit slow at present. Each time I think that I have the whole story I read something new which points me in a new direction.
The following site looks a bit strange but has some interesting discussion about port flow and port size which has got me thinking again.
Another thing which I came across regarding porting which you may find interesting is as follows. While the document relates to a square tube it is easy to see how this can be applied to a circular port.