3/5/7 angle valve jobs?
Discussion
Mr Puma, I'd be very interested in your opinion for a new composite intake manifold with integral throttles I'm working on for a TVR 500 engine.
If you had a clean sheet of paper, what would your requiremnts be for a fast road engine running fully mapped fuel and ignition. Head porting allowed (but no scope for replacement heads to place inlet ports in a better location)
So far I'm trying to keep the whole runner as straight as possible (obviously even length) with the flattest of curves keeping the runner as long as possible and the butterflys as central as possible and away from the head. 45mm butterflies and parralel trumpets with a smooth conical reduction and shape change to inlet port area.
Are there any 'non secret tips' you can give a complete novice having a half educated/half guessed 'play' before I go and waste a few weeks evenings and produce something worse than a stock TVR 500 manifold and plenumn?
Ta, muchly. Virgil...a budding 'Dave'
If you had a clean sheet of paper, what would your requiremnts be for a fast road engine running fully mapped fuel and ignition. Head porting allowed (but no scope for replacement heads to place inlet ports in a better location)
So far I'm trying to keep the whole runner as straight as possible (obviously even length) with the flattest of curves keeping the runner as long as possible and the butterflys as central as possible and away from the head. 45mm butterflies and parralel trumpets with a smooth conical reduction and shape change to inlet port area.
Are there any 'non secret tips' you can give a complete novice having a half educated/half guessed 'play' before I go and waste a few weeks evenings and produce something worse than a stock TVR 500 manifold and plenumn?
Ta, muchly. Virgil...a budding 'Dave'
Pumaracing said:
The design of single butterfly plenum manifolds is not one of my strong areas so I'd appreciate more explanation of your thoughts above and what would ideally be done to optimise the design to which I suspect you'll answer "much more plenum volume".
I'd lift the intake runners clear of the walls of the plenum as the first thing if it were me.
Steve_D said:
Pumaracing said:
....The overlap of the trumpet edges might be hurting things a bit....
I think that may just be the way they are sat on the bench.Steve
They are Kinsler ITBs, all the linkages etc are too.
http://www.kinsler.com/page--Home-Page--13.html
Pumaracing said:
Max_Torque said:
I bet the "charge robbing" is horrendous on that^^^^ ally manifold !
The design of single butterfly plenum manifolds is not one of my strong areas so I'd appreciate more explanation of your thoughts above and what would ideally be done to optimise the design to which I suspect you'll answer "much more plenum volume".Currently rethinking and redesigning my entire inlet system
I almost dont want to mention cam profiles!
Word got out I'd say.
I have something to add to this thread. First of all, what I believe what would be required for port speed recovery, is what is commonly described as laminar flow. It's why dimples on golf balls work, but not on leading edges of airplane wings. It's what gives down force, but not drag on formula 1 car bodies. A lot of math has been done on this in formula one, but also in rocket engine design. Check out de Laval nozzles for some very interesting reading on expansion, speed and shape theories for gas flow.
All that brings me to a question the Daves might be able to share some discussion, wisdom or just a good joke on. What -if any- influence does exhaust pipe material have on the ideal length, diameter and such for exhaust headers? I'm certain that the temperature of the exhaust gasses changes dramatically once they exit he cylinder head. Speed, pressure and temperature have an influence on the speed the gasses travel, their resonance frequency and all. This makes it hard for me to believe that any simplified equation for exhaust header length and diameter will give me close to full benefits. Is the chosen material, thickness and optionally, wrapping of the headers significant here? Adding to that question, I recently read something on another forum where some knowledgeable people were discussing the speed of the exhaust flow and the shape and expansion rate of the port. This is where my de Laval reference came from. Would anyone here have experimented with this and did it work?
I have something to add to this thread. First of all, what I believe what would be required for port speed recovery, is what is commonly described as laminar flow. It's why dimples on golf balls work, but not on leading edges of airplane wings. It's what gives down force, but not drag on formula 1 car bodies. A lot of math has been done on this in formula one, but also in rocket engine design. Check out de Laval nozzles for some very interesting reading on expansion, speed and shape theories for gas flow.
All that brings me to a question the Daves might be able to share some discussion, wisdom or just a good joke on. What -if any- influence does exhaust pipe material have on the ideal length, diameter and such for exhaust headers? I'm certain that the temperature of the exhaust gasses changes dramatically once they exit he cylinder head. Speed, pressure and temperature have an influence on the speed the gasses travel, their resonance frequency and all. This makes it hard for me to believe that any simplified equation for exhaust header length and diameter will give me close to full benefits. Is the chosen material, thickness and optionally, wrapping of the headers significant here? Adding to that question, I recently read something on another forum where some knowledgeable people were discussing the speed of the exhaust flow and the shape and expansion rate of the port. This is where my de Laval reference came from. Would anyone here have experimented with this and did it work?
every days a school day and all that 
Well I'm just new to the site, but I must say that so far I am impressed with what I have read here on port flow etc. I want to start doing my own heads for my engine and am in the process of building my own flowbench so I'm interested to learn if some of you are interested to teach
Cheers !
Cheers !
Workshop said:
Well I'm just new to the site, but I must say that so far I am impressed with what I have read here on port flow etc. I want to start doing my own heads for my engine and am in the process of building my own flowbench so I'm interested to learn if some of you are interested to teach
Cheers !
Before you start building an expensive/complex bench you might want to read my porting book (out about April)- it's already listed on Amazon.Cheers !
The method I detail to build a bench can be done for very little (under $150) and could be finished in a weekend. Also it will produce more meaningful results than one of those big blue benches costing upward of $10,000. The book will also explain a ton of tech you simple won't get unless you wring it out of Dave Baker (sorry Dave - had to get that one in!!)
David Vizard
Thanks , that's a lot of sleeps till April !!!
Yeah, I hope Mr Baker will add a few comments as well.
I've ported a couple of sets of my own heads before but they were pretty much just a clean up and I felt like blind Freddy because I was really taking a guess as to what I was doing. This limited me to what I could do with the port.I'm now a a stage where I want go further with a port but most importantly understand what I am doing it and why I'm doing it.
Cam selection is another thing I'm studying now. Most times I usually let the grinder choose the profile but I decided to put in the study and start to select and spec my own.
It's all very interesting stuff
Cheers
Yeah, I hope Mr Baker will add a few comments as well.
I've ported a couple of sets of my own heads before but they were pretty much just a clean up and I felt like blind Freddy because I was really taking a guess as to what I was doing. This limited me to what I could do with the port.I'm now a a stage where I want go further with a port but most importantly understand what I am doing it and why I'm doing it.
Cam selection is another thing I'm studying now. Most times I usually let the grinder choose the profile but I decided to put in the study and start to select and spec my own.
It's all very interesting stuff
Cheers
Workshop said:
Thanks , that's a lot of sleeps till April !!!
Yeah, I hope Mr Baker will add a few comments as well.
I've ported a couple of sets of my own heads before but they were pretty much just a clean up and I felt like blind Freddy because I was really taking a guess as to what I was doing. This limited me to what I could do with the port.I'm now a a stage where I want go further with a port but most importantly understand what I am doing it and why I'm doing it.
Cam selection is another thing I'm studying now. Most times I usually let the grinder choose the profile but I decided to put in the study and start to select and spec my own.
It's all very interesting stuff
Cheers
The book covers cam selection and why it is important for a head porter to know what is going on here. leaving it to the cam company is - well ----- not the best idea. They can only take you so far. With what i cover in the book you will be able to outspec evewn the best cam grinders - yes really!!Yeah, I hope Mr Baker will add a few comments as well.
I've ported a couple of sets of my own heads before but they were pretty much just a clean up and I felt like blind Freddy because I was really taking a guess as to what I was doing. This limited me to what I could do with the port.I'm now a a stage where I want go further with a port but most importantly understand what I am doing it and why I'm doing it.
Cam selection is another thing I'm studying now. Most times I usually let the grinder choose the profile but I decided to put in the study and start to select and spec my own.
It's all very interesting stuff
Cheers
DV
David Vizard said:
The book covers cam selection and why it is important for a head porter to know what is going on here. leaving it to the cam company is - well ----- not the best idea. They can only take you so far. With what i cover in the book you will be able to outspec evewn the best cam grinders - yes really!!
DV
On camshafts.DV
I assume most camshafts are now designed based on computer models ? How reliable are the computer models ?
Certainly, as far as the US goes, everyone on LS forums blabs "custom cam this, custom cam that, you need a cam designed for your etc etc"
While this may be true, I always retort that these custom cams they all dream of are nothing but guesswork and no way will the be optimal for their setup unless they test dozens of profiles back to back. They may be a custom grind, but they are still a guess.
Or can some of these dynosim type programs really give good results ?
stevieturbo said:
On camshafts.
I assume most camshafts are now designed based on computer models ?
Or can some of these dynosim type programs really give good results ?
If you completely and accurately characterise your complete valvetrain (in terms of masses, spring rates, friction, geometery, torsional and longitudinal stiffness) and accurately measure the differential pressure each valve sees vs crank angle, then yes, a "computer" generated cam profile will be absolutely spot on with regard to valve motion control. You then need a perfectly correlated multi dimensional fluid dynamics model to be able to optimise the gas exchange process across the complete speed and load operating zone. We do it all the time, it's now absolutely std in terms of OEM development (we will generally have a fully modelled engine before ANY hardware is ever made.I assume most camshafts are now designed based on computer models ?
Or can some of these dynosim type programs really give good results ?
For an aftermarket firm? i'm going to go with "best guess" as the optimium solution......... ;-)
stevieturbo said:
On camshafts.
I assume most camshafts are now designed based on computer models ? How reliable are the computer models ?
Certainly, as far as the US goes, everyone on LS forums blabs "custom cam this, custom cam that, you need a cam designed for your etc etc"
While this may be true, I always retort that these custom cams they all dream of are nothing but guesswork and no way will the be optimal for their setup unless they test dozens of profiles back to back. They may be a custom grind, but they are still a guess.
Or can some of these dynosim type programs really give good results ?
It took me 18 years to research and write my Cam-Master program. It is deadly accurate to the point I flat out challenge the cam companies to beat it with their expertise. Has not happened yet. No the program is not for sale but the output from it has allowed me to come up with an entirely different way to select cams far more accurately than a regular catalog (and just as, if not more accurate, than these big main frame simulations) If you have a copy of my small block or big block performance on a budget books the cam selection section will leave you in zero doubt as to the cam you are gong to need for the builds and variations there-of within the book. I assume most camshafts are now designed based on computer models ? How reliable are the computer models ?
Certainly, as far as the US goes, everyone on LS forums blabs "custom cam this, custom cam that, you need a cam designed for your etc etc"
While this may be true, I always retort that these custom cams they all dream of are nothing but guesswork and no way will the be optimal for their setup unless they test dozens of profiles back to back. They may be a custom grind, but they are still a guess.
Or can some of these dynosim type programs really give good results ?
The cylinder head book out shortly explains that if you port heads without any real understanding of what that cylinder head may require in terms of valve events relative to the spec of major other parts (bore, stroke etc) all you have done is make your work look less effective. Not so good if you want to be seen as the best. My 'How to Build HP' book is used in several universities now as required first year reading because it cuts right to the chase and sidesteps all the myths and erroneous info put out about cam event selection.
As of now my Chevy books allow a complete novice (and I mean a complete novice such as a 10 year old girl who has no idea how and engine even works) to select a cam in 15 seconds flat that will outperform any catalog cam out there and in 99% of cases better than most of the so-called engine experts.
The selection method is a breakthrough.
Given long enough all the major cam companies are likely (once they have overcome the not-invented-here syndrome) to adopt the method I am using in my books because it is so much better.
I hope I have made my point here.
Max_Torque said:
You then need a perfectly correlated multi dimensional fluid dynamics model to be able to optimise the gas exchange process across the complete speed and load operating zone. We do it all the time, it's now absolutely std in terms of OEM development (we will generally have a fully modelled engine before ANY hardware is ever made.
uncorrelated models that have the wrong closed valve heat transfer, wrong friction and wrong wall friction numbers so will predict as much as 10% if not more out 
Still better than the after market technicians though
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