Does quench affect power?

[ptuomov]

Why not put in the biggest intake valves that fit and aren’t shrouded and then keep the port small at valve guides?

The biggest unshrouded would be around 33 mm at intake and around 28 mm at exhaust. That 4-valve head has shrouded areas already from OEM status on. May we define how much shrouding still improves flow to find the optimum for the application? I assume this is very engine and application specific .

The stock 35mm valves are pretty big, but I think others have installed 36mm or even 37mm intake valves in those heads.

I agree that the valves never be completely unshrouded, just the flow from the second intake valve alone guides the flow from the valve.

In my humble opinion, the larger valves in freely shaped ports allow for a larger fraction of the flow to be directed on the side of the valve head that promotes tumble. I don’t see any meaningful penalty from larger valves in terms of combustion quality, as the larger valve reliefs can presumably be made smaller at the same flow rates.

[hoffman900]

Why not put in the biggest intake valves that fit and aren’t shrouded and then keep the port small at valve guides?

The biggest unshrouded would be around 33 mm at intake and around 28 mm at exhaust. That 4-valve head has shrouded areas already from OEM status on. May we define how much shrouding still improves flow to find the optimum for the application? I assume this is very engine and application specific .

The stock 35mm valves are pretty big, but I think others have installed 36mm or even 37mm intake valves in those heads.

I agree that the valves never be completely unshrouded, just the flow from the second intake valve alone guides the flow from the valve.

In my humble opinion, the larger valves in freely shaped ports allow for a larger fraction of the flow to be directed on the side of the valve head that promotes tumble. I don’t see any meaningful penalty from larger valves in terms of combustion quality, as the larger valve reliefs can presumably be made smaller at the same flow rates.

Toyota used laser clad valve seats so they could run less valve margin, and run a larger intake valve, because with their tumble designs, they aren’t using the full diameter. The Honda paper with the 2 valve hemi does something similar.

[LotusElise]

The stock 35mm valves are pretty big, but I think others have installed 36mm or even 37mm intake valves in those heads....I don’t see any meaningful penalty from larger valves in terms of combustion quality, as the larger valve reliefs can presumably be made smaller at the same flow rates.

I got you point like following:

• Running an e.g. 36 mm intake valve at the same throat diameter = decreasing the valve-throat-ratio
• Resulting in the same impulse promoting velocity in some kind and improves the over valve head flow, means a higher tumble number
• The piston valve relief depth can be smaller when one aims for the same scavenging efficiency which would improve combustion because of a lower max dome height

Is that correct?

[LotusElise]

Toyota used laser clad valve seats so they could run less valve margin, and run a larger intake valve, because with their tumble designs, they aren’t using the full diameter. The Honda paper with the 2 valve hemi does something similar.

I see your point, pointing in a similar direction like the above mentioned one. What is the title of that mentioned paper, or would you even share it?

[hoffman900]

Chevy R07 combustion chamber and pistons, from PME:



12:1 compression, 4.190in bore.

[hoffman900]

Toyota used laser clad valve seats so they could run less valve margin, and run a larger intake valve, because with their tumble designs, they aren’t using the full diameter. The Honda paper with the 2 valve hemi does something similar.

I see your point, pointing in a similar direction like the above mentioned one. What is the title of that mentioned paper, or would you even share it?

Toyota Dynamic Force Engine:
https://www.youtube.com/watch?v=cWHq-Qr903g


https://www.hondarandd.jp/point.php?pid=976&lang=en

Research on Combustion Improvement Techniques by Intake Valve Offset and Squish Effect , 2013

Reported in this paper are the technologies for improvement of combustion efficiency by applying two simple methods to a single cylinder, 110 cm3 displacement, four-stroke, two-valve gasoline engine.
In the first attempt, we tried to improve combustion efficiency by increasing tumble of the air-fuel mixture flow. To increase tumble, we devised an offset intake valve design in which a part of the intake valve was located outside of the cylinder bore. With this offset intake valve configuration, a part of the inlet port perimeter was blocked causing disturbance of air-fuel mixture flow along the cylinder wall that resulted in a strong turbulence. The increased turbulence permitted lean burn at an air-fuel ratio leaner by two points, reducing Indicated Specific Fuel Consumption by 4.8% from that of the base engine. With the intake valve shifted outwards against the cylinder bore, the spacing next to the exhaust valve increased, allowing the intake valve diameter to be enlarged to compensate for the deterioration of the maximum power.
In the second attempt, we tried to improve combustion efficiency by increasing the reversed squish flow of the air-fuel mixture. As the means to increase reversed squish flow, we employed a slant-parallel squish configuration. With the application of this squish arrangement, the margin against knocking generation was enhanced and the compression ratio was increased to 9.5 from the original 9.0 while reducing the Indicated Specific Fuel Consumption by 2.6%. The offset intake valve design coupled with the high compression ratio produced by the slant-parallel squish design lowered the Indicated Specific Fuel Consumption by 6.0% compared to the base engine.

[hoffman900]

Here are 37cc chambers for a Ford RY45 Pro 4 / Trophy Truck engine. Makes 15:1 compression with pistons like you see in that R07 example:

[juuhanaa]

Why not put in the biggest intake valves that fit and aren’t shrouded and then keep the port small at valve guides?

The biggest unshrouded would be around 33 mm at intake and around 28 mm at exhaust. That 4-valve head has shrouded areas already from OEM status on. May we define how much shrouding still improves flow to find the optimum for the application? I assume this is very engine and application specific .

The stock 35mm valves are pretty big, but I think others have installed 36mm or even 37mm intake valves in those heads.

I agree that the valves never be completely unshrouded, just the flow from the second intake valve alone guides the flow from the valve.

In my humble opinion, the larger valves in freely shaped ports allow for a larger fraction of the flow to be directed on the side of the valve head that promotes tumble. I don’t see any meaningful penalty from larger valves in terms of combustion quality, as the larger valve reliefs can presumably be made smaller at the same flow rates.

I remembered another example of a historic Renault engine...

https://www.youtube.com/watch?v=UU9lBxQaJrs


Group N and A Homologations dated 1991:

https://historicdb.fia.com/sites/defaul ... roup_n.pdf

https://historicdb.fia.com/sites/defaul ... roup_a.pdf


Highlights from papers dated 1991:

Cylinder capacity: 440,96cm3
Total: 1764cm3
Bore: 82mm
Total minimum volume of combustion chamber: 48,7cm3
Minimum volume of a combustion chamber in the cylinder head: 43,39cm3
Maximum diameter of the inlet valves: 30,9mm
Cylinder head inlet ports, manifold side: 1595,44mm2


I have also found some Renault cylinder head flow data from Stan Weiss site, but here is a calculus regarding "hole process":

F7P harmonics.png

FHD0024.JPG

-juhana

[juuhanaa]

It is a pain, because of memories.

But good memories finally, aren't those?

Link below is a visual example of the R19 ECU injector firing I remember F7R engine basis on a R19 wiring was different in terms of starting and throttle response, compared to Megane F7R stock sequential fuel injection, but i also had flaws in optimizing those ECUs with different combinations..

https://www.youtube.com/watch?v=vjnIE2lWB_M


Anyway... My rally car has currently F7R engine basis with stock injector location, MoTec M400, 4.2bar fuel pressure and 380cc injectors/3bar. It is different compared to F4R setup where injectors were mounted further away from the valves, because F7R engine start using less amount of fuel combined with a later injection timing.

Now back to R19 ECU and experimental stuff. Its just me thinking loud and oversimplifying things.. if starting and throttle response is some how worse doe to wet flow, then i also may need more harmonious mixture on upper revs? So possible tighter cold quench clearance especially, if i use a straighter intake port design and a bigger dish in a piston...


A couple Renault F7P related combustion videos that i found on youtube, and i forgot to mention in my previous post:

https://www.youtube.com/watch?v=aDfqsR7s5X8

https://www.youtube.com/watch?v=XqBemF7lOek



-juhana

[MetricMuscle]

Toyota used laser clad valve seats so they could run less valve margin, and run a larger intake valve, because with their tumble designs, they aren’t using the full diameter. The Honda paper with the 2 valve hemi does something similar.

I've read the Honda paper about the 110cc engine but didn't it make less power? They were able to increase compression by 0.5 without detonation, which may have been the purpose of the project, but did anything else happen? Was fuel economy improved?

It is funny how technology can eliminate the need for certain hobbies. Toyota is done worrying about Short Side Radius, apologies to all of you highly skilled race engine porting gurus but we find it just too much trouble to deal with so yup, straight in she goes. It's what the intake charge really wants after all, if they are honest, none of them like to go around bends, we have all known this for a long time.

[juuhanaa]

Toyota used laser clad valve seats so they could run less valve margin, and run a larger intake valve, because with their tumble designs, they aren’t using the full diameter. The Honda paper with the 2 valve hemi does something similar.

I've read the Honda paper about the 110cc engine but didn't it make less power? They were able to increase compression by 0.5 without detonation, which may have been the purpose of the project, but did anything else happen? Was fuel economy improved?

It is funny how technology can eliminate the need for certain hobbies. Toyota is done worrying about Short Side Radius, apologies to all of you highly skilled race engine porting gurus but we find it just too much trouble to deal with so yup, straight in she goes. It's what the intake charge really wants after all, if they are honest, none of them like to go around bends, we have all known this for a long time.

Please open a little how you add fuel into the mixture and what did you find?

I have run direct injection Alfa-Romeo, but i just cant call it a day after finishing second My point is, when i next time went to compete at the same track using French car, i won. So it had to be the SSR ---> troubles are good

just kidding...

https://youtu.be/NpQ2OCT5ukY



-juhana

[hoffman900]

Toyota used laser clad valve seats so they could run less valve margin, and run a larger intake valve, because with their tumble designs, they aren’t using the full diameter. The Honda paper with the 2 valve hemi does something similar.

I've read the Honda paper about the 110cc engine but didn't it make less power? They were able to increase compression by 0.5 without detonation, which may have been the purpose of the project, but did anything else happen? Was fuel economy improved?

It is funny how technology can eliminate the need for certain hobbies. Toyota is done worrying about Short Side Radius, apologies to all of you highly skilled race engine porting gurus but we find it just too much trouble to deal with so yup, straight in she goes. It's what the intake charge really wants after all, if they are honest, none of them like to go around bends, we have all known this for a long time.

Darin Morgan said on the Chevy IRL engines, which they had access to a 100” H2O bench, that the bench and engine responded to making it straighter and straighter, to the point they got rid of the short side radius entirely.

[juuhanaa]

How the valves are arranged in that Chevy IRL engine?

[Tom68]

Toyota used laser clad valve seats so they could run less valve margin, and run a larger intake valve, because with their tumble designs, they aren’t using the full diameter. The Honda paper with the 2 valve hemi does something similar.

I've read the Honda paper about the 110cc engine but didn't it make less power? They were able to increase compression by 0.5 without detonation, which may have been the purpose of the project, but did anything else happen? Was fuel economy improved?

It is funny how technology can eliminate the need for certain hobbies. Toyota is done worrying about Short Side Radius, apologies to all of you highly skilled race engine porting gurus but we find it just too much trouble to deal with so yup, straight in she goes. It's what the intake charge really wants after all, if they are honest, none of them like to go around bends, we have all known this for a long time.

Darin Morgan said on the Chevy IRL engines, which they had access to a 100” H2O bench, that the bench and engine responded to making it straighter and straighter, to the point they got rid of the short side radius entirely.

Straighter as in looooong valve so port is more aligned with valve stem I'd suggest, straighter inlet ports was the only thing the Repco Brabham engine had going for it in 1966 and that worked out pretty good.

[Alkyfool]

Chevy R07 combustion chamber and pistons, from PME:



12:1 compression, 4.190in bore.

Novice observations...is the intake side of the piston much deeper than the exhaust? Is this to encourage mixture motion with valve open and then to bias the mixture to the intake valve side at TDC compression