Does quench affect power?

General engine tech -- Drag Racing to Circle Track

Moderator: Team

User avatar
juuhanaa
HotPass
HotPass
Posts: 1193
Joined: Fri Oct 15, 2021 7:14 am
Location: Finland
Contact:

Re: Does quench affect power?

Post by juuhanaa »

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

chamber.jpg
You do not have the required permissions to view the files attached to this post.
A balanced person dares to stagger, and modify ports bigger
User avatar
juuhanaa
HotPass
HotPass
Posts: 1193
Joined: Fri Oct 15, 2021 7:14 am
Location: Finland
Contact:

Re: Does quench affect power?

Post by juuhanaa »

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 :D

Attached one page of homologation that includes info related to this subject. Full version can be found on internet, just google fia historic database.

Screenshot_20220928-083115 (1).jpg
You do not have the required permissions to view the files attached to this post.
A balanced person dares to stagger, and modify ports bigger
LotusElise
Member
Member
Posts: 99
Joined: Tue Mar 09, 2021 10:05 am
Location: BW

Re: Does quench affect power?

Post by LotusElise »

juuhanaa wrote: Tue Sep 27, 2022 10:28 am I have lift to valve diameter ratio of .309 and 1.3mm cold squish clearance. Max lift and and piston TDC no contact.
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.
juuhanaa wrote: Tue Sep 27, 2022 10:28 amInteresting to see how this response on a dyno to "slight" intake advance. I mean the rally car i have mentioned in other topic.. Its a coctail engine, but round and round we go :D
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
LotusElise
Member
Member
Posts: 99
Joined: Tue Mar 09, 2021 10:05 am
Location: BW

Re: Does quench affect power?

Post by LotusElise »

juuhanaa wrote: Tue Sep 27, 2022 1:56 pm Here is a picture of matching chamber and piston with some dimensions...Cold squish clearance was approx 1.3mm
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
User avatar
juuhanaa
HotPass
HotPass
Posts: 1193
Joined: Fri Oct 15, 2021 7:14 am
Location: Finland
Contact:

Re: Does quench affect power?

Post by juuhanaa »

LotusElise wrote: Wed Sep 28, 2022 7:44 am
juuhanaa wrote: Tue Sep 27, 2022 1:56 pm Here is a picture of matching chamber and piston with some dimensions...Cold squish clearance was approx 1.3mm
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.
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.

Fascinating but at the same time worrying that I'm single and here we are talking about small squish area! :lol: Thanks again LotusElise

Old bmw piston.jpg


-juhana
You do not have the required permissions to view the files attached to this post.
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
User avatar
ptuomov
Guru
Guru
Posts: 3587
Joined: Fri Aug 07, 2009 3:52 am
Location:

Re: Does quench affect power?

Post by ptuomov »

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.
Paradigms often shift without the clutch -- https://www.youtube.com/watch?v=cxn-LxwsrnU
https://www.instagram.com/ptuomov/
Put Search Keywords Here
Bigchief632
Pro
Pro
Posts: 449
Joined: Tue Aug 09, 2022 9:20 am
Location: US

Re: Does quench affect power?

Post by Bigchief632 »

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
User avatar
juuhanaa
HotPass
HotPass
Posts: 1193
Joined: Fri Oct 15, 2021 7:14 am
Location: Finland
Contact:

Re: Does quench affect power?

Post by juuhanaa »

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
You do not have the required permissions to view the files attached to this post.
A balanced person dares to stagger, and modify ports bigger
User avatar
juuhanaa
HotPass
HotPass
Posts: 1193
Joined: Fri Oct 15, 2021 7:14 am
Location: Finland
Contact:

Re: Does quench affect power?

Post by juuhanaa »

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,
A balanced person dares to stagger, and modify ports bigger
User avatar
juuhanaa
HotPass
HotPass
Posts: 1193
Joined: Fri Oct 15, 2021 7:14 am
Location: Finland
Contact:

Re: Does quench affect power?

Post by juuhanaa »

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.
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...
A balanced person dares to stagger, and modify ports bigger
LotusElise
Member
Member
Posts: 99
Joined: Tue Mar 09, 2021 10:05 am
Location: BW

Re: Does quench affect power?

Post by LotusElise »

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.
You are welcome. I need to recalculate it later...
DAMPFHAMMER engine:
2000 ccm, Honda K20 NA engine
4000 rpm bandwidth of at least 192 ftlb
310 hp@8200 rpm
LotusElise
Member
Member
Posts: 99
Joined: Tue Mar 09, 2021 10:05 am
Location: BW

Re: Does quench affect power?

Post by LotusElise »

juuhanaa wrote: Wed Sep 28, 2022 10:32 am it would be nice to have little bit more below 8k. Then i would be bussy in settin the diff and chassy.
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 :wink:. 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
LotusElise
Member
Member
Posts: 99
Joined: Tue Mar 09, 2021 10:05 am
Location: BW

Re: Does quench affect power?

Post by LotusElise »

ptuomov wrote: Wed Sep 28, 2022 10:18 am The trouble begins with large included valve angle heads run normally aspirated at high rpms (so large bore, short stroke) on high octane fuel.
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
User avatar
ptuomov
Guru
Guru
Posts: 3587
Joined: Fri Aug 07, 2009 3:52 am
Location:

Re: Does quench affect power?

Post by ptuomov »

LotusElise wrote: Wed Sep 28, 2022 2:01 pm
ptuomov wrote: Wed Sep 28, 2022 10:18 am The trouble begins with large included valve angle heads run normally aspirated at high rpms (so large bore, short stroke) on high octane fuel.
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.
Where would you add the material to the head?

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:

.
K20RadDeck3.jpg
.

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.
You do not have the required permissions to view the files attached to this post.
Paradigms often shift without the clutch -- https://www.youtube.com/watch?v=cxn-LxwsrnU
https://www.instagram.com/ptuomov/
Put Search Keywords Here
LotusElise
Member
Member
Posts: 99
Joined: Tue Mar 09, 2021 10:05 am
Location: BW

Re: Does quench affect power?

Post by LotusElise »

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.
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.

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
Post Reply