Burn patterns on piston and chamber

[steve cowan]

He is using ms109 fuel. Makes what ?1.5hp per cube . Highly doubt anyone could make more with parts being used.

That burn pattern or lack of tells me there is quite a bit left.A good running engine has a nice even burn across 90 percent of piston and chamber.It should have a light gray/tan light dusty texture if right.When you have a sludge look across 1/3 of your piston and no even heat or cover across the rest ,you are leaving pretty good power behind.Could be cyl prep or ring type issue but I see allot of room in the valve job in that pic that needs addressed also.It will taking going to a bigger valve to get all the cuts sharp and correct again,it don't look like it could be fixed any other way.jmo.No disrespect to anyone involved but I see allot could be improved on.I never put a engine together without roll radius the sharp edges and laying some texture on top of piston to help with a even burn.im no fan of flattops to get a nice mixture motion,if that's used your valve job and head and ring seal needs to 100 percent on point.

Appreciate everyone feedback and no my feelings are not hurt lol.i am here to learn and any constructive criticism is fine by me.
Just to clarify-
Heads 165cc ported to 186cc
2.10" avg csa
1.94" - 1.5" valves
89% throat on intake
Bowl 100% of intake valve.
I done valve job with stones as that's all I have.
40,50,60,70,82
I ported heads,intake and built engine.
The block was honed using profilometer by my machine shop I use,they honed to JE recommendations.
Cam is a comp roller
240 - 256 @ 0.050 "
406 lobes
1.7 - 1.5 rockers.
Ran best ET,mph at track 109 ICL,109 LSA.
Made 522 ft/ lbs @ 5300rpm
570hp @ 6600rpm
Down 5 hp @ 7000rpm.
3620 pound Streeter
1.46 in 60ft
6.71 @ 101mph
10.62 @ 124. 65mph.
So I have some work to do by the sounds of it, I wonder if the MS109 fuel is not suitable for 11.4 compression?
I used it because of the short cam worried about cylinder pressure.
This year it had 20 dyno pulls,30 passes at track and maybe 500 miles of street, so not alot of work.
I have plenty to think about.

[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.

If he added texture to the pistons would that allow more incomplete combusted hydrocarbons to adhere to the piston with no real change to the status quo? Piston top would read different than with a shiny top that carbon is less susceptible to stick to with no difference in outcome?

What do you find unfavorable with flat top pistons and in what application?

What’s the preference over flat tops?

I have always put a texture on piston when radius work on edges done.I have never saw a light carbon trail across entire piston not work.Nobody likes their comb chamber shiny smooth?
I always have made power with light dome on piston over flattop.If I have to crowd a chamber down so hard to make comp with a flattop I can't get a valve in it I want.If I'm going to trouble and expense to build an engine ,I'm going after every aspect!Now if a guy can't seal his motor then a piston of any roughness isn't gona save it.

[Lloyd klem]

We were running like 9.04-9.06 and 148 mph.We were just altering some poor fuel to find a little more power.Our timing was on edge for fuel being used ,it got me my 8.98 and 150 mph ticket tho.We had made enough attempts and realized I probably didn't have enough fuel to drive back home 55 miles.So I loaded it on buddies trailer.Its been sitting his shop since.I figured I pull plugs today and set valves and drive it home.

Must be making around 900hp NA................impressive for only 383ci, driving to and from track.

What's peak rpm's?

Never been on Dyno but it's runs best in 8800-9200 area.Its been tried all over the board.It is 3.525 stroke.So rpm is it's friend.It has nice pieces in it and really cam is not way stupid or springs being run.Im gona tear it down and freshen ,it's sold.

[SpeierRacingHeads]

Super Stock engine off the dyno.

Chad,
Are you using leaded fuel??

NHRA has a list of fuels. Tried them all. It made the same power with VPc12 and I like the smell. Brings back memories!

[Lloyd klem]

Super Stock engine off the dyno.

Chad,
Are you using leaded fuel??

NHRA has a list of fuels. Tried them all. It made the same power with VPc12 and I like the smell. Brings back memories!

You run b32,b33,or b37 Phillips back in yester year?

[SpeierRacingHeads]

Chad,
Are you using leaded fuel??

NHRA has a list of fuels. Tried them all. It made the same power with VPc12 and I like the smell. Brings back memories!

You run b32,b33,or b37 Phillips back in yester year?

No, never did. We ran the Union 76 one year.

[rgalajda]

“From memory we were 8% richer than stoich for MS109.”

“Engine came off dyno and went in my car showing 12.5 AFR @ WOT.
I have used 2 other carbs but worked on the 12.5:1 at the track 
950 hp (750) 850 annular. 
Idle afr is 12.5
Cruise on transfer slot is 15.0
WOT steady 12.5.”


Your cruise rpm would have to be low to be on the transfer slot alone.
A 950 HP and a 850 annular are completely different carbs when looking at fuel atomization. The 950 came in different sized venturi and throttle bores depending on which model.
These holley carbs never run 15:1 AFR at cruise rpm without work. They are always way to rich.

Fuel wash usually means fixing fuel atomization. Using the correct booster for the size of the venturi .
Mechanical Secondary could be opening too soon. Too much venturi area too soon.
More intake temperature for vaporizing of fuel.
Port shaping and sizing of the cylinder head and intake manifold. Manifold finish.

[SpeierRacingHeads]

Here is what I have been doing for several years. I had a Mondello for several years and it was a complicated MOFO. So I took what I seen and applied to the simple, but effective, alcohol/dykem..

This is my SS head. You can see it came off the dyno HORRIBLE and pathetic. So I confirmed what I was seeing with alcohol/dykem. Then worked on the port, more. The actual chamber and the dykem chamber look a little different, but remember this was at .800 lift and steady state. But it still gives you a visual of what is and will happen. It's hillbilly all the way! But you can learn something..

Then after I got the chamber how I felt was better, I worked on mixture motion, shown in the first picture.

[Erland Cox]

I asked what acceleration enrichment was for and only got a few answers.
Most of it is to wet the manifold and cylinder head runner walls after they have been dried out when throttle was closed.
The EFI strategy for this is called X-tau.

http://www.megamanual.com/ms2/xtau.htm

In tests I have seen that burr finished walls hold less fuel than 60 grit walls.
I could use less fuel and less acc. enrichment with burr finish.

Erland

[juuhanaa]

I asked what acceleration enrichment was for and only got a few answers.
Most of it is to wet the manifold and cylinder head runner walls after they have been dried out when throttle was closed.
The EFI strategy for this is called X-tau.

http://www.megamanual.com/ms2/xtau.htm

In tests I have seen that burr finished walls hold less fuel than 60 grit walls.
I could use less fuel and less acc. enrichment with burr finish.

Erland

Interesting that enrichment is said to be needed to wet the walls, but at the same time you needed less enrichment on drier, burr finish walls?

Where did you spray the fuel? Injector location changes enrichment and timing.



-juhana

[Erland Cox]

I used Weber carburetors as carbs and I used TB:s with injectors in them.
The burr finish holds less fuel than the 60 grit surface.
So when the walls have dried during off throttle they needs less fuel to go to full wet again.

Erland

[brentry]

200,000 mile stock LS head ,did this test years ago, and it's spark plug. 1st thing I noticed was black on plug is exactly where the blue hit the plug on bench. All 8 old plugs had same black spot.
Sanded carbon off before flowing so I could see where the dye hit

[juuhanaa]

I used Weber carburetors as carbs and I used TB:s with injectors in them.
The burr finish holds less fuel than the 60 grit surface.
So when the walls have dried during off throttle they needs less fuel to go to full wet again.

Erland

Ok, thanks.

[HQM383]

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.

If he added texture to the pistons would that allow more incomplete combusted hydrocarbons to adhere to the piston with no real change to the status quo? Piston top would read different than with a shiny top that carbon is less susceptible to stick to with no difference in outcome?

What do you find unfavorable with flat top pistons and in what application?

What’s the preference over flat tops?

I have always put a texture on piston when radius work on edges done.I have never saw a light carbon trail across entire piston not work.Nobody likes their comb chamber shiny smooth?
I always have made power with light dome on piston over flattop.If I have to crowd a chamber down so hard to make comp with a flattop I can't get a valve in it I want.If I'm going to trouble and expense to build an engine ,I'm going after every aspect!Now if a guy can't seal his motor then a piston of any roughness isn't gona save it.

Makes sense for building compression without combustion chamber compromises. What about flat tops for engines that don’t need big compression such as a 10.5:1 deal?

Two schools of thought on piston top finish are having a smooth top (sometimes smooth and shiny) to avoid carbon build up and reflect heat from the piston and back into the chamber and the other is to do as you do and texture the piston to purposefully get a layer of carbon as an insulator to the piston and keep heat in the chamber. As a hypothetical, with identical combustion events occurring on both of these piston finishes wouldn’t we see a different carbon pattern?

I see carbon deposits as the poorly burnt excess hydrocarbons that we have in our A/F ratio for making power to ensure all oxygen that is drawn in is consumed (excess fuel has that cooling effect too). It’s the hydrocarbon molecules that didn’t have enough oxygen molecules to consume it. On Steve’s low mileage engine it looks like deposits are beginning to form around the area of combustion initiation that’s imperfect and not long after that better combustion eventuates. Also carbon is sticking around the hottest areas first. The carbon can’t yet stick to all the clean smoothish surfaces but will likely spread over time. Barely any coloring on the cylinder wall above top ring but it eventually would have. The wet look of the carbon area could be fuel gum and varnish due to oxidization of partially burnt fuel. Running rich mixtures are not often going to be perfectly homogeneous either with rich and lean pockets with each combustion event. Rich pocket = carbon pocket. In such a low mileage engine as Steve’s I’d be concerned if incomplete burned fuel was all over the combustion space already without a rougher texture on components for it to adhere to. But like you said we can be successful with different experiences so I certainly accept where you’re coming from.

Tell us more about your 383 street/strip combo running 8s and 150? That’s one kick ass combo that can be driven to and from the track.

[Tom68]

Just to clarify-
Heads 165cc ported to 186cc
2.10" avg csa
1.94" - 1.5" valves
89% throat on intake
Bowl 100% of intake valve.
I done valve job with stones as that's all I have.
40,50,60,70,82
I ported heads,intake and built engine.
The block was honed using profilometer by my machine shop I use,they honed to JE recommendations.
Cam is a comp roller
240 - 256 @ 0.050 "
406 lobes
1.7 - 1.5 rockers.
Ran best ET,mph at track 109 ICL,109 LSA.
Made 522 ft/ lbs @ 5300rpm
570hp @ 6600rpm
Down 5 hp @ 7000rpm.
3620 pound Streeter
1.46 in 60ft
6.71 @ 101mph
10.62 @ 124. 65mph.
So I have some work to do by the sounds of it, I wonder if the MS109 fuel is not suitable for 11.4 compression?
I used it because of the short cam worried about cylinder pressure.
This year it had 20 dyno pulls,30 passes at track and maybe 500 miles of street, so not alot of work.
I have plenty to think about.

S C 383.jpg

Well I'll be interested to see if more piston and chamber area covered in carbon for the same amount of work done results in more power. Because more power is what you're after, what everything looks like is less important as long as nothings melted.

If one black dot in the middle of the piston makes the most power on the dyno, then in the absence of a dyno we should be shooting to replicate that one black dot.

Seems like it's doing pretty good now for intake port volume, intake valve size and mid size camshaft.

Just looked in the plug hole of a boat motor I threw together last Summer that spent a few weeks running up and down the Murray, it appears all black inside, but then I think it is pig rich and fuel does turn into carbon.