Does quench affect power?

[Tom68]

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

Or is that giving us a clue as to which valve is the most open on overlap stroke at tdc.

[hoffman900]

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

Or is that giving us a clue as to which valve is the most open on overlap stroke at tdc.

Likely this.

At some level, what is going in the chamber is beyond what we can observe with our eyes or even see on a flowbench, and needs to be modeled with high end software and verified with very expensive in-situ measuring equipment.

[juuhanaa]

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

Or is that giving us a clue as to which valve is the most open on overlap stroke at tdc.

Likely this.

At some level, what is going in the chamber is beyond what we can observe with our eyes or even see on a flowbench, and needs to be modeled with high end software and verified with very expensive in-situ measuring equipment.

It's interesting what we can do with our eyes closed and without those tools, but i dont have the skills to use those tools let alone that i recognize what they are. Speed-Talk helps,



-juhana

[swampbuggy]

Hello Alkyfool, it is hard to say from the picture if the exhaust relief is shallower than the intake side but you can Bet that the depth in the intake valve relief was such to give enough clearance in the area of 15 degrees before and after T.D.C. on the exhaust / intake stroke . Mark H.

[wkuran]

It's also why Pro Stock uses steel rods. I can't show the piston top, but here's a picture of the underside and the rods. This engine had >40 passes on it. You can still see the dimple in the bearing coating from the dial gauge.

Pro Stock Teardown - Jeg Coughlin Jr.jpg

I wouild be slightly upset if someone damaged (dimple) the bearing coating while using a dial gauge.

[wkuran]

Bear in mind if the piston is just barely kissing the head at WOT, it is only doing so at TDC overlap. It's not kissing the head at TDC combustion.

If you close the throttle at high rpm then the piston could touch the head at both TDCs, instead of just TDC overlap.

I know of only one TDC - when the piston is at the top if its stroke. What are TDC overlap and TDC combustion?

[wkuran]

Keep it real? KISS?
I don't need to test it. It's been tested. Ad nauseum.
Look. Yes. Quench matters. In an SBC that's indisputable. Yes. It's from the internet. Yes, we're discussing this via the internet.
General consensus from the thousands of test done (look it up) quench improves combustion efficiency, reduces the propensity for detonation, increases power and reduces emissions.
There is too much evidence to say otherwise. To keep asking how much is enough or too little, or by how much, etc, etc, is a waste of time.
It's up to you to find that out for your own particular ride.
For my particular ride, it'll be a choice between .034" and .047".
Done.

It sounds as if you are talking about squish - not quench. I interested in learning about quench and squish but the two terms are used interchangably in many posts, making it difficult to understand the differeces. If you do mean squish, I agree that there is testing that validates its benefit. The documented benefits of quench seem to be less clear.

Thanks.

[HQM383]

Bear in mind if the piston is just barely kissing the head at WOT, it is only doing so at TDC overlap. It's not kissing the head at TDC combustion.

If you close the throttle at high rpm then the piston could touch the head at both TDCs, instead of just TDC overlap.

I know of only one TDC - when the piston is at the top if its stroke. What are TDC overlap and TDC combustion?

In a 4 cycle engine the piston is at tdc twice during those 4 cycles with two completely different events happening each time. The two times at tdc per 4 cycles need description for clarification when discussing. Combustion and Overlap is just that. Until a functioning valve train is installed there is only one tdc.

[Bigchief632]

Keep it real? KISS?
I don't need to test it. It's been tested. Ad nauseum.
Look. Yes. Quench matters. In an SBC that's indisputable. Yes. It's from the internet. Yes, we're discussing this via the internet.
General consensus from the thousands of test done (look it up) quench improves combustion efficiency, reduces the propensity for detonation, increases power and reduces emissions.
There is too much evidence to say otherwise. To keep asking how much is enough or too little, or by how much, etc, etc, is a waste of time.
It's up to you to find that out for your own particular ride.
For my particular ride, it'll be a choice between .034" and .047".
Done.

It sounds as if you are talking about squish - not quench. I interested in learning about quench and squish but the two terms are used interchangably in many posts, making it difficult to understand the differeces. If you do mean squish, I agree that there is testing that validates its benefit. The documented benefits of quench seem to be less clear.

Thanks.

Squish is generally referencing 2 strokes, quench is 4 strokes. It's essentially the same thing, but it's way more critical in a 2 stroke.

[brentry]

That's completely false
It is not way more critical in a 2t
It depends.
plenty of pump head designs make good power with loose squish in a 2t.

[af2]

That's completely false
It is not way more critical in a 2t
It depends.
plenty of pump head designs make good power with loose squish in a 2t.

Exactly!!

[gunt]

i know its outside your general engines
i built 2 ej20 subaru , one is stroker , the 2.0 i rose the compression , all stock made 350 , the 2.1 i left the compression lower due to [ i was tinking stock cams stroker building compression ] this has a way bigger turbo fit for 450, but it only managed 360 , @14deg ign , but it seams it was knock limiting , take out timing rise boost same ting , low boost rise ign same ting , was it the quench that ultimatlly i changed and fked this , 9.5 v 8.3:1

[gunt]

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

i seen the guys at 4piston racing , stating they had to put back a short side radius on honda's and fords , thing it was an easy 100cfm gain with performance proven and more / higher option available

-juhana

[juuhanaa]

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

i seen the guys at 4piston racing , stating they had to put back a short side radius on honda's and fords , thing it was an easy 100cfm gain with performance proven and more / higher option available

-juhana

Ok, thats cool but 4piston racing and me doing folkrace in the same sentense sounds funny. Anyway here is the SSR i mention and made without a flow bench. Well, lets see if flow testing will change that.

Screenshot_20221210-014748.jpg

-juhana

[wkuran]

I know of only one TDC - when the piston is at the top if its stroke. What are TDC overlap and TDC combustion?

In a 4 cycle engine the piston is at tdc twice during those 4 cycles with two completely different events happening each time. The two times at tdc per 4 cycles need description for clarification when discussing. Combustion and Overlap is just that. Until a functioning valve train is installed there is only one tdc.

Thanks for the explanation. Is this a two cylce thread? If so that may be why I find so many post to be confusing.