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Clevo120Y

crossflow porting results

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Agreed. The manifold is a terrible restriction in speedway classes forced to run the visually standard manifold. Marusic's head makes some solid numbers. 1.925 valve would be helping there, but none the less very good results.

Brenton also removes a lot of the intake guide to the point that there is none protruding into the intake runner. We have never done this due to concerns about valve stability under sustained high rpm.  I imagine it would be less of a concern in short duration motor sport. Perhaps it's time to try that in a runner and see if it makes a difference. The guide boss is actually a fairly big restriction to flow.  I know Ken Lowe makes his own nitrous nozzles for this very reason.  Hmm. More things to try. 

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On 10/15/2017 at 8:49 PM, CHESTNUTXE said:

for us that are interested in these results but dont no what they mean can someone explain how it reads like the head flows 380hp with so much lift ? is that estimated cam lift ?

Thats just a good starting point of a possible power figure and not to be taken as gospel per say.

So back to getting...Brentons head flowed as good as 440hp yet the engine made 380plus. My head flows only 260cfm or 390hp but has run 11.5 and 120.6 mph. So weight shifted it shows 417 @ the crank on ET and 460 on MPH (by Wallace racing site which use's the moroso slide rule) to move 1497kg with driver.

My car gained hp on the dyno but showed ZERO ET improvement last time around. This time the only dyno has been the track and tuning has been done with AFR's plugs fuel and laps.  

So yes it's a good guide but also shows dyno's and flow benches are just tools and to be taken with a grain of salt. Track is the only place where the truth shows,good or bad. 

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Just now, dex said:

How bout smooth pasteing the manifolds ,? 

You still need to port em...Some people use epoxies to seal up,remake or build up areas looking for gains. Simply putting goo in there and smoothing it will not improve anything.

Most leave a textured finish to the cyl heads and manifolds to help attomisation.     

 

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Some CNC mobs are putting golf ball dimples in certain areas to keep the flow attached. Goes against your instinct to look at but interesting nonetheless.

Sent from my CPH1607 using Tapatalk

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2 hours ago, gerg said:

Some CNC mobs are putting golf ball dimples in certain areas to keep the flow attached. Goes against your instinct to look at but interesting nonetheless.

Sent from my CPH1607 using Tapatalk
 

Flow seperation is a killer, has the effect of making your ports smaller.

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Flow seperation is a killer, has the effect of making your ports smaller.
If it does work, I could see merit in it if used on the short turn.

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As stated before but I'll post it so all can read anyway.Shows why inlet to exhuast percentages is pointless and a waste of time and how chamber recovery (Matt) is important.     

 

COMBUSTION CHAMBER DESIGN

Here is a little known fact: the chamber is part of the intake port. The chamber walls are an extension of the intake port design and effect how it flows dynamically in the running engine. As the intake valve opens, pressure recovery takes place. To put it simply, this means that the air exiting the valve is being slowed down at the correct rate. The flow bench will flat out lie to you in this case, because a poorly designed chamber can flow more air than a proper one! People forget that the intake pressures we deal with on a flow bench are 5.5 times less than what you’re dealing with in the running engine. The dynamics of the running engine cannot be fully simulated on the flow bench. This is one of those instances.

EXHAUST PORT DESIGN

I have bad news. You can not design an exhaust port on a flow bench the way you do an intake port. If you’re designing exhaust ports to flow the most air possible, you’re destroying the engines ability to blow the cylinder down and exhaust properly. If you design an exhaust port to flow the most air possible on the flow bench, the power will be lower, fuel signal will decrease, and the engines acceleration will suffer. Professionals understand that designing an exhaust port on the flow bench has nothing to do with how much it flows, but everything to do with how it flows and at what air speed. The exact size, shape, and air speed of the port in conjunction with how smooth it flows, are the primary points to consider. Personally, I care very little about how much the exhaust port flows. It’s at the very bottom of my list of importance. I don’t try and make the exhaust port flow as much as possible, because I have been down that path hundreds of times and it’s a dead end street! The pressures the exhaust port has to deal with in the running engine are hundreds of times greater than the flow bench could possibly simulate. Ask yourself this: why would you design a port using 1 PSI test pressure at 70°F, when it’s actually flowing at 500PSI+ and 1300°F?

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I never doubted your combustion chamber comments if that is why my name is in brackets? I just like to see what has been done and works.

Haha... "little known fact". This guy must have just learnt it. I am sure the guy is very smart, but that is a bit rich. The air doesn't stop at the port so that is obvious. But he is correct about the pressure thing which is why Vizard recommends the variable pressure flow bench.

The influence of exhaust to inlet port has been understood for decades, but perhaps not the finer details which like everything fluid dynamics related may never fully be. The so called rules of inlet to exhaust ratio only apply if you are using the maximum valve space allowable and are still based on some very old experiments from Charles Taylor (despite some claiming it as their own). So the post is right there too. Making an exhaust valve smaller  (unless there is something horrible wrong) is not going to make you faster and if your exhaust is flowing at least 60% of your inlet your not giving that much up. But, if it is flowing 90% you are not either unless you have hammered the port in the process. I think that influence of exhaust tunning is often overstated and Sly's post also suggests a hint of that.

The very last point made in Sly's post is the main point, why do we test at a constant arbitrary pressure drop?  Because it's easy and gives us a good starting point to work with. If you were to design a new head using CFD, you wouldn't do it, but at least it gives you some information to work with.

It is a good post with some good points, but he is still talking in black art.

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Agreed Matt. It is a black art and whilst the unknown author in Sly's post doesn't mention anything about intake to exhaust percentages, he does raise some very valid points.  In particular the flow bench being a constant pressure, something the engine in dynamic form never sees.

He sort of contradicts himself a little when he says "Professionals understand that designing an exhaust port on the flow bench has nothing to do with how much it flows, but everything to do with how it flows and at what air speed. The exact size, shape, and air speed of the port in conjunction with how smooth it flows, are the primary points to consider.  

 Isn't that what the bench is measuring, how it flows and at what air speed?  Perhaps he is saying peak flow is immaterial but how it flows is more important? Agreed that designing the exhaust port primarily on flow bench readings is probably not the best way to go.  But you want ex flow.  Look at efi Windsor heads.  They are just junk because you can't even fit your thumb in the exhaust port.  Improving the intake on those heads is an excercise in frustration, cause they still won't work - hence the reason aftermarket alloy Windsor heads sell so well. 

For me the flow bench is a tool used to measure gains (or not) from changes in the (complete) port shape, including chamber of course. Vizard and others theories are just that, theories. Everyone has their own idea on what makes engines fast.  Supercars is a classic example of this. All different ideas, but they all come together and are within tenths of each other. 

For me it's purely physics. The more you get in - the more you have to get out.  More air in, equals more fuel in, equals more waste to deal with. Yes the exhaust is a pressure system - not a suction system but it must be efficient or cylinder evacuation suffers. 

Anthony changes the heads on his flow bench so that they are blowing when the exhaust port is flowed.  Yes it's not the same as the dynamics happening inside the engine, but it's as good a tool as any to measure stuff that can then be tested in the real world to see if there are gains or not.

 

 

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The "guy" is Darrin Morgan of Reheer and Morrison. So no didn't just learn it. I was once told he knew nothing. Based on his success and the teams I'd say I know why knows more and who is the successful one.     

Yes you can use it as a base and a tool and even he still doe's derrrrrrr but alot are missing the point of values,how to use it and what to look for.That part seemed obvious to me and some could use the info or not LOL 

Everyone can take it how you want but I'm yet to find a person who has used his work/seminars or tips go backwards.Real results,Just saying.

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100%.  And we will just keep doing what we do.  When you do a head for a bloke and he puts it on and goes and sets a track lap record at an Aussie title, is the fastest car in qualifying,  highest point scorer after all the heats and qualifies on pole for an Aussie title against some of the biggest budgets and best cars in Australia - you must be doing something right.

Real results as you say. Oh and he was saying he had the wrong gear set in, but it still pulled through that. Imagine what it would do with the correct gear set.  Oh you don't have to. It went to the Qld title and won that feature by the length of the straight after starting in 13th. Another real result. 

I have no doubt that the Mr Darrin Morgan of Reheer and Morrison knows his stuff as I'm sure he is well paid to do that job and that job alone. Myself and Cam both do what we do as we are interested in the field and when time permits, we play. I'd love to be paid to do this stuff all day, as would cam, but the reality is the amount of people making a proper living from it is minimal.  

Theories abound and always will.

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No doubt Mr Morgan knows some stuff, but he needs to work on being less condescending in his writing style ("little known fact..." is still making me giggle). Still some good points came out of it.

The reality is that if you want an optimized head, you need an engineer to do it and probably one with a PhD and that is going to cost you big time and nobody is going to do it. That's why its great to see Ando and the like putting in hard work and seeing what works for themselves. If we can see what works and what does not we can all reverse engineer to understand why, just like these "professionals".

Keep it up guys, I'm too tight and lazy atm so I will sit back and watch you.

Build a variable pressure flow bench Ando.

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Just as power is needed to turn your workshop air compressor, it stands to reason that on an engine, any pressure built up inside the cylinder on the exhaust stroke would have the engine working against it, with a proportional loss of power ie: pumping losses.

Of course getting the exhaust to flow well is always a compromise to the potential inlet flow, but I suppose that's where the "black art" lies.... In finding that sweet spot.

For argument's sake, a 4" piston pushing 5 psi of pressure imparts a force of 62.83 lbs on the conrod. On a 3.5" stroke crank, this results in a peak of 9.16 lb-ft of torque (ie when the crank and rod are perpendicular). What that works out at on average I don't know how to calculate (sine curve perhaps?) but that plus reduced scavenging has to add up to a lot.

Theories indeed...

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9 hours ago, ando76 said:

100%.  And we will just keep doing what we do.  When you do a head for a bloke and he puts it on and goes and sets a track lap record at an Aussie title, is the fastest car in qualifying,  highest point scorer after all the heats and qualifies on pole for an Aussie title against some of the biggest budgets and best cars in Australia - you must be doing something right.

Real results as you say. Oh and he was saying he had the wrong gear set in, but it still pulled through that. Imagine what it would do with the correct gear set.  Oh you don't have to. It went to the Qld title and won that feature by the length of the straight after starting in 13th. Another real result. 

I have no doubt that the Mr Darrin Morgan of Reheer and Morrison knows his stuff as I'm sure he is well paid to do that job and that job alone. Myself and Cam both do what we do as we are interested in the field and when time permits, we play. I'd love to be paid to do this stuff all day, as would cam, but the reality is the amount of people making a proper living from it is minimal.  

Theories abound and always will.

Same car won all the same races car using John White Racing power and as you said many time's that car wasn't legal Ando. Don't know if I would call that a achievement myself been as honest and non derogatory as I can here.

I don't see Darrin as condescending more like just showing telling everyone the biggest thing they miss. As his txt is aimed to help not slur or slag on anyones work (hence posting it here for people to read) just help. Can't control how people read or take written txt. Use it or don't,agree or don't argue or cry or don't.

In the end it's all just about the cars,the rest is meaningless to me and over. 

            

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You may want to do your research on that car a little better. It never set fastest time at an Aussie title with the previous head, nor broke the Lismore track record with that other head.  It never top qualified on points in an Aussie title and certainly wasn't able to pull the wrong gear set before. As to the legality of the car, my opinion matters for squat. It passed scrutineering before and after that meeting (the top 5 cars all get inspected post race) and the Queensland title, so therefore it is legal.  

Your entitled to your opinion on whether it's an achievement or not, as am I. Sadly this thread is going down the same road as a couple of weeks back. Never mind we should have some further results shortly to bring it back on track. 

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