Does quench affect power?
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Re: Does quench affect power?
Here is a picture of matching chamber and piston with some dimensions. This one survived, but eventually threw a light weight connecting rod (my own mistake at least in machining). Dished version surprised me, felt more stronger and bent a crank, but thats a good thing. Please forgive me paint art and 2,3 or 4cc margin of error when measuring, but we should get the idea. Cold squish clearance was approx 1.3mm
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A balanced person dares to stagger, and modify ports bigger
Re: Does quench affect power?
I have told earlier that my static cr been on 11 range, but in reality that is approximate and it includes errors in measuring. Anyway its an value where i have been willing to reduce. I started to remember VW did also something in the 90s. Pictures above was added by request
Attached one page of homologation that includes info related to this subject. Full version can be found on internet, just google fia historic database.
Attached one page of homologation that includes info related to this subject. Full version can be found on internet, just google fia historic database.
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A balanced person dares to stagger, and modify ports bigger
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Re: Does quench affect power?
My 310 hp 2-Liter-NA-engine has a valve lift-diameter-ratio of 0.366 and 1.0 mm squish heiht and 12 % squish bore-area.
Very nice. Yeap, IM has the biggest effect on peak power engine speed as well as on VE, as the pressure peak at IVC is very important, the runner length as well as the plenum volume and intake pipe design before TB. Here the 1D-simulation approach is a very good supporter, which can't be done in that detail with simple acoustic approaches.
DAMPFHAMMER engine:
2000 ccm, Honda K20 NA engine
4000 rpm bandwidth of at least 192 ftlb
310 hp@8200 rpm
2000 ccm, Honda K20 NA engine
4000 rpm bandwidth of at least 192 ftlb
310 hp@8200 rpm
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Re: Does quench affect power?
Squish area, only from piston side, don't know if they match the squish area of the head too, is 16.5 % according your data: bore = 84 mm and segment height is 11.5 mm.
DAMPFHAMMER engine:
2000 ccm, Honda K20 NA engine
4000 rpm bandwidth of at least 192 ftlb
310 hp@8200 rpm
2000 ccm, Honda K20 NA engine
4000 rpm bandwidth of at least 192 ftlb
310 hp@8200 rpm
Re: Does quench affect power?
Thanks! Ah of course, i have not looked these things with this precision before. F7R chamber was untouched, so it was approx 8mm on intake side and 6mm on exhaust in relation to 84mm bore wall. In my small head it makes sense that there was less carbon residual on intake side of the piston + some small vortex looking patterns.LotusElise wrote: ↑Wed Sep 28, 2022 7:44 amSquish area, only from piston side, don't know if they match the squish area of the head too, is 16.5 % according your data: bore = 84 mm and segment height is 11.5 mm.
Fascinating but at the same time worrying that I'm single and here we are talking about small squish area! Thanks again LotusElise
-juhana
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Last edited by juuhanaa on Wed Sep 28, 2022 10:22 am, edited 1 time in total.
A balanced person dares to stagger, and modify ports bigger
Re: Does quench affect power?
If your compression ratio requirements are such that you can run an approximately flat top piston in a four-valve pentroof engine, you're just going to win win win whether you have squish or not. Just run a high tumble port.
The trouble begins with large included valve angle heads run normally aspirated at high rpms (so large bore, short stroke) on high octane fuel.
The trouble begins with large included valve angle heads run normally aspirated at high rpms (so large bore, short stroke) on high octane fuel.
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Re: Does quench affect power?
Just an honest question, what are you looking to "improve'? And what do you think you will gain? Just curious. How much time are you willing to spend to make a "gain" that you can't even define? Not trying to be a jerk here, I just don't understand the obsession with this.
Maximum power using simple logic and common sense
Re: Does quench affect power?
The way i see it, its one thing that has to work with the others. In Finland guys run engines like this. it would be nice to have little bit more below 8k. Then i would be bussy in settin the diff and chassy.
-juhana
-juhana
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A balanced person dares to stagger, and modify ports bigger
Re: Does quench affect power?
Then we have Germans, Italians and French..
Aand a lot comes from USA.
https://www.youtube.com/watch?v=i3Xk-hcqVt4
https://www.youtube.com/watch?v=aR4DlG8jDdI
enjoy,
Aand a lot comes from USA.
https://www.youtube.com/watch?v=i3Xk-hcqVt4
https://www.youtube.com/watch?v=aR4DlG8jDdI
enjoy,
A balanced person dares to stagger, and modify ports bigger
Re: Does quench affect power?
Obviously my understanding is inadequate in this subject and i dont know how much tumble i need, but my gut says there might be more torq with less tumble for my application...ptuomov wrote: ↑Wed Sep 28, 2022 10:18 am If your compression ratio requirements are such that you can run an approximately flat top piston in a four-valve pentroof engine, you're just going to win win win whether you have squish or not. Just run a high tumble port.
The trouble begins with large included valve angle heads run normally aspirated at high rpms (so large bore, short stroke) on high octane fuel.
A balanced person dares to stagger, and modify ports bigger
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Re: Does quench affect power?
You are welcome. I need to recalculate it later...juuhanaa wrote: ↑Wed Sep 28, 2022 9:58 am Thanks! Ah of course, i have not looked these things with this precision before. F7R chamber was untouched, so it was approx 8mm on intake side and 6mm on exhaust in relation to 84mm bore wall. In my small head it makes sense that there was less carbon residual on intake side of the piston + some small vortex looking patterns.
DAMPFHAMMER engine:
2000 ccm, Honda K20 NA engine
4000 rpm bandwidth of at least 192 ftlb
310 hp@8200 rpm
2000 ccm, Honda K20 NA engine
4000 rpm bandwidth of at least 192 ftlb
310 hp@8200 rpm
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Re: Does quench affect power?
A little squish always help to reduce knock as the flame speed beyond 90 % MFB get little affected by this, so to say in the echo of it . If you want a little more below 8 krpm you would need to advance the intake cam or retard, if not already too retarded, the exhaust cam. Just from the alternation of load and VE thingy side. What ignition timings do you run for MBT from 6000-8000 rpm?
DAMPFHAMMER engine:
2000 ccm, Honda K20 NA engine
4000 rpm bandwidth of at least 192 ftlb
310 hp@8200 rpm
2000 ccm, Honda K20 NA engine
4000 rpm bandwidth of at least 192 ftlb
310 hp@8200 rpm
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- Member
- Posts: 99
- Joined: Tue Mar 09, 2021 10:05 am
- Location: BW
Re: Does quench affect power?
Welcome to the amazing Honda K-series world: awesome VE possible but combustion is very slow. I run IGT's at 130 % VE, approximately 130 bar cylinder peak pressure (NA induction) of around 30° BTDC, while MBT is around 8°-10° ATDC. To get this chamber 10° faster from 8000-10000 rpm is my goal. For that 12 ccm dome volume you need squish to reduce IGT delay and to push the heat up of around 0-10 % MFB. One thing which I will do is to reduce dome volume by reduceing the head volume by around 5 ccm.
DAMPFHAMMER engine:
2000 ccm, Honda K20 NA engine
4000 rpm bandwidth of at least 192 ftlb
310 hp@8200 rpm
2000 ccm, Honda K20 NA engine
4000 rpm bandwidth of at least 192 ftlb
310 hp@8200 rpm
Re: Does quench affect power?
Where would you add the material to the head?LotusElise wrote: ↑Wed Sep 28, 2022 2:01 pmWelcome to the amazing Honda K-series world: awesome VE possible but combustion is very slow. I run IGT's at 130 % VE, approximately 130 bar cylinder peak pressure (NA induction) of around 30° BTDC, while MBT is around 8°-10° ATDC. To get this chamber 10° faster from 8000-10000 rpm is my goal. For that 12 ccm dome volume you need squish to reduce IGT delay and to push the heat up of around 0-10 % MFB. One thing which I will do is to reduce dome volume by reduceing the head volume by around 5 ccm.
In my personal and uneducated opinion, adding material to the sides of the 4-valve combustion chamber is a mistake if one has to run a dome on the piston. By sides I mean the area on the outsides between intake and exhaust valves. I wouldn't do that if you have to rely on squish for combustion. If you rely on squish for combustion, that material is better added to the piston crown, because then the squish is directed not to the piston dome (as it would if you add material to the head) but to the spark plug (when adding the material to piston and leaving the side roof as it is). (On flat top or dished pistons, adding material to the sides in the head is probably fine, but a large included valve angle head isn't going to run well normally aspirated without a piston dome.)
The best place to add material in the head would in my uneducated opinion be behind the intake valves and between the intake valves and behind the exhaust valves and between the exhaust valves (cooling issues aside). A little like this:
.
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Then start with a dome that exactly fills the combustion chamber, add valve reliefs, and use a large-radius spherical dish to take out as much of the crown under the spark plug as you can while still making your geometric CR number.
Just uneducated opinions there.
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Re: Does quench affect power?
That's the plan for now: the back of the intake and exhaust valve, integrated a better inflow guide (wall shape) for less broken flow Vorticies. That adds at max. 5 ccm to the head and gives a 5 ccm more design freedome at the dome, which is already 1 mm below the spark plug without adding material for a 12.7:1 CR. The picture is from Larry Widmer's latest K-series head design, can be bought in the aftermarket as Larry sold his stuff to two companies. He built a complete own casted K-series head, amazing stuff and quite a genious idea.ptuomov wrote: ↑Wed Sep 28, 2022 3:54 pm The best place to add material in the head would in my uneducated opinion be behind the intake valves and between the intake valves and behind the exhaust valves and between the exhaust valves (cooling issues aside)...Then start with a dome that exactly fills the combustion chamber, add valve reliefs, and use a large-radius spherical dish to take out as much of the crown under the spark plug as you can while still making your geometric CR number.
Toyota made for their SkyActive-Chamber exactly that on the piston, but it is a direct injected engine, so the PFI system need a wider bowl radius. Once squish tumbles into that piston bowl, that would be nice .
DAMPFHAMMER engine:
2000 ccm, Honda K20 NA engine
4000 rpm bandwidth of at least 192 ftlb
310 hp@8200 rpm
2000 ccm, Honda K20 NA engine
4000 rpm bandwidth of at least 192 ftlb
310 hp@8200 rpm