Burn patterns on piston and chamber

General engine tech -- Drag Racing to Circle Track

Moderator: Team

Post Reply
steve cowan
Guru
Guru
Posts: 2253
Joined: Wed Jul 27, 2011 5:22 am
Location: brisbane AUSTRALIA

Burn patterns on piston and chamber

Post by steve cowan »

20221203_182359.jpg
20221203_180151.jpg
Curious on what to look for and which direction one should take when looking at burn patterns.
Spark plug wetting seems to be a issue for a lot of early OEM type cylinder heads.
The fuel used here was MS109
I am interested in opinions on what guys think is happening in the burn process.
You do not have the required permissions to view the files attached to this post.
steve c
"Pretty don't make power"
mag2555
Guru
Guru
Posts: 4584
Joined: Sun Sep 18, 2011 11:31 am
Location: Heading for a bang up with Andromeda as we all are.

Re: Burn patterns on piston and chamber

Post by mag2555 »

Do you have a back cut on the intake valve?
You can cut a man's tongue from his mouth, but that does not mean he’s a liar, it just shows that you fear the truth he might speak about you!
steve cowan
Guru
Guru
Posts: 2253
Joined: Wed Jul 27, 2011 5:22 am
Location: brisbane AUSTRALIA

Re: Burn patterns on piston and chamber

Post by steve cowan »

mag2555 wrote: Sat Dec 03, 2022 4:08 pm Do you have a back cut on the intake valve?
50 degree seats and no back cuts
steve c
"Pretty don't make power"
Lloyd klem
Member
Member
Posts: 115
Joined: Wed Jul 27, 2022 8:58 pm
Location: Midwest

Re: Burn patterns on piston and chamber

Post by Lloyd klem »

You could pull a bunch of fuel out of that.Your pistons don't have near enough coverage imo.Need to get some texture too them.
Lloyd klem
Member
Member
Posts: 115
Joined: Wed Jul 27, 2022 8:58 pm
Location: Midwest

Re: Burn patterns on piston and chamber

Post by Lloyd klem »

Yes,you are leaving a bunch of power behind there.Im no flat top piston fan at all .That being said even on alky piston should have 95 percent plus coverage if your engine is sealed and your valve job is correct.
Erland Cox
Guru
Guru
Posts: 4142
Joined: Sun Jan 29, 2006 9:46 pm
Location: Lund in Sweden
Contact:

Re: Burn patterns on piston and chamber

Post by Erland Cox »

Image

With burr finish in ports and chamber.
Should I try burr finish on the piston too?

Erland
User avatar
Tom68
HotPass
HotPass
Posts: 2541
Joined: Mon Feb 07, 2022 3:43 am
Location: VIC OZ

Re: Burn patterns on piston and chamber

Post by Tom68 »

steve cowan wrote: Sat Dec 03, 2022 2:48 pm 20221203_182359.jpg20221203_180151.jpg
Curious on what to look for and which direction one should take when looking at burn patterns.
Spark plug wetting seems to be a issue for a lot of early OEM type cylinder heads.
The fuel used here was MS109
I am interested in opinions on what guys think is happening in the burn process.
Hottest part stains first, hold it full load at 6000 for several minutes and I think it'll look a lot different.
Ignorance leads to confidence more often than knowledge does.
Nah, I'm not leaving myself out of the ignorant brigade....at times.
In-Tech
Vendor
Posts: 2812
Joined: Wed Apr 21, 2010 4:35 am
Location: Fresno, CA

Re: Burn patterns on piston and chamber

Post by In-Tech »

I assume this is an engine you built so I don't have to ask you about texture in the intake manifold or ports. The fuel is dropping out of suspension and you need less quench area. A lot of people thru the years have added fuel coolers #-o . Cold air, hot fuel is a key. And yes, I agree with others, you are extremely rich. Some of this could be the fuel suspension problem.
Heat is energy, energy is horsepower...but you gotta control the heat.
-Carl
Lloyd klem
Member
Member
Posts: 115
Joined: Wed Jul 27, 2022 8:58 pm
Location: Midwest

Re: Burn patterns on piston and chamber

Post by Lloyd klem »

Erland Cox wrote: Sat Dec 03, 2022 6:14 pm Image

With burr finish in ports and chamber.
Should I try burr finish on the piston too?

Erland
If my stuff looked that bad I would consider it and I don't burr finish anything.Jmo.It is consistent tho across whole layout.Looks way over fueled/oily compared to what I'm used to seeing.I would work on my valve job and really look at my honing procedure in a mess like that.I would check what ring edges and ring lands look like also.
Last edited by Lloyd klem on Sat Dec 03, 2022 7:34 pm, edited 1 time in total.
steve cowan
Guru
Guru
Posts: 2253
Joined: Wed Jul 27, 2011 5:22 am
Location: brisbane AUSTRALIA

Re: Burn patterns on piston and chamber

Post by steve cowan »

Tom68 wrote: Sat Dec 03, 2022 6:20 pm
steve cowan wrote: Sat Dec 03, 2022 2:48 pm 20221203_182359.jpg20221203_180151.jpg
Curious on what to look for and which direction one should take when looking at burn patterns.
Spark plug wetting seems to be a issue for a lot of early OEM type cylinder heads.
The fuel used here was MS109
I am interested in opinions on what guys think is happening in the burn process.
Hottest part stains first, hold it full load at 6000 for several minutes and I think it'll look a lot different.
Good point tom,
Engine was dynoed for Max power.
When looking at this chamber and piston one has to consider some street miles and driving around pits as well.it looks to me like the engine was cold so to speak.
The carbon is not a build up but like a stain if that makes sense.
steve c
"Pretty don't make power"
SpeierRacingHeads
Vendor
Posts: 937
Joined: Sun May 13, 2012 1:28 pm
Location: KS
Contact:

Re: Burn patterns on piston and chamber

Post by SpeierRacingHeads »

Super Stock engine off the dyno.
You do not have the required permissions to view the files attached to this post.
Speier Racing Heads
Chad Speier
785-623-0963
steve cowan
Guru
Guru
Posts: 2253
Joined: Wed Jul 27, 2011 5:22 am
Location: brisbane AUSTRALIA

Re: Burn patterns on piston and chamber

Post by steve cowan »

Lloyd klem wrote: Sat Dec 03, 2022 5:15 pm You could pull a bunch of fuel out of that.Your pistons don't have near enough coverage imo.Need to get some texture too them.
From memory we were 8% richer than stoich for MS109.
Is the unleaded fuel making this look worse than what it is??
We can not run leaded fuel in Australia.
steve c
"Pretty don't make power"
steve cowan
Guru
Guru
Posts: 2253
Joined: Wed Jul 27, 2011 5:22 am
Location: brisbane AUSTRALIA

Re: Burn patterns on piston and chamber

Post by steve cowan »

20221113_170103.jpg
All exhaust ports and valves look like this
You do not have the required permissions to view the files attached to this post.
steve c
"Pretty don't make power"
steve cowan
Guru
Guru
Posts: 2253
Joined: Wed Jul 27, 2011 5:22 am
Location: brisbane AUSTRALIA

Re: Burn patterns on piston and chamber

Post by steve cowan »

In-Tech wrote: Sat Dec 03, 2022 6:29 pm I assume this is an engine you built so I don't have to ask you about texture in the intake manifold or ports. The fuel is dropping out of suspension and you need less quench area. A lot of people thru the years have added fuel coolers #-o . Cold air, hot fuel is a key. And yes, I agree with others, you are extremely rich. Some of this could be the fuel suspension problem.
I thought on a 23 degree head you need that quench to help with mixture motion etc.
Just for reference this has 0.030"
Piston to head clearance.
steve c
"Pretty don't make power"
1980RS
Guru
Guru
Posts: 1636
Joined: Thu Oct 13, 2016 10:03 am
Location:

Re: Burn patterns on piston and chamber

Post by 1980RS »

My chambers on the L-29 heads and piston crowns looked super after using a burr finish in the intake ports and chambers. I am sold on doing the burr finish after testing it with 2 different sets of heads. Never had intake ports so clean after a few races.
Post Reply