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No longer mom's grocery getter(1991 244)

Re: timing

Sorry, my question came off like the rest of my comments: dickish. From reading Njal's post, it sounded like the big advantage was to be able to add extra timing and to run leaner. Was curious what you were going to do.

:cheers:


WHY GROOVE?!


I want to increase the detonation threshold. I want to be able to run more advanced ignition timing(if necessary to make more power). I want to have better idle quality and reduced emissions at idle while still having a decently large camshaft(see the emissions test results from last year below). I want to be able to drive around the car at obnoxiously low rpm when I don't need more power for better gas mileage. I want better acceleration under 2000rpm without going to a smaller camshaft. I want to be able to run even higher static compression with an even larger camshaft in the future, without giving up all of my low rpm drivability.

The head is now off, I just need to do the grooves after I figure out exactly how I'm going to do them and then put the head back on the car. I am NOT even cleaning the carbon build-up in the chambers or piston tops so it's a back to back comparison. Not changing the spark plugs(or their rotation). Nothing is being changed but the grooves and a fresh oil change. The oil that's in the engine now only has 2,000 miles on it and is clean still, barely darker than fresh.
 
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Car's current spec:

-230k mile, original bottom end, never been touched and with some cylinder bore wear and very slight oil consumption. Full synthetic oil.
-Stock 530 cylinder head with low hours/mileage since rebuilding(was used on the General Leif for a while). Very mild port work. ~.032" shaved off of it. Untouched chambers.
-H camshaft advanced 2? with valve clearances initially set to ~.015" on the intakes and ~.017" on the exhausts.
-.036" MLS headgasket.
-87? C thermostat, stock cooling system with proper air guides.
-Stock b230F intake manifold, air filter and airbox with exhaust preheat routed to cold air and flapper removed.
-KGT/Timos Type 1 header with 44mm primaries and custom Type 3/51mm sized secondaries added. Shortened secondaries when compared to original header using Columbia River Mandrel Bending's tubing and merge.
-Custom 2.5" exhaust with a small Magnaflow spun/race cat, a small Magnaflow muffler for a resonator in stock location and a Dynomax Super Turbo(junk, just wanted it quieter but it really needs softer motor mounts) at the back.
-LH2.4 + EZK, various tunes including stock and not depending on what I want and the temperature and so on.
-Stock ignition components, NGK BPR7ES spark plugs.
-M47 transmission w/3.73 rear end(Trutrac diff).
-225/45-17 DWS 06 tires on Tethys.
-Full interior with added sound deadening and a 10" sub w/amp in the trunk.
-Chevron "Supreme" 92 octane gas, full tank.

Combustion chamber pictures after 12,000 miles since last cleaned/installed(sorry for size):

27982920_10103204399320068_3522055292817958118_o.jpg


#1-3 look generally like this:
27797354_10103204399340028_5504345452282279657_o.jpg


#4 has more build-up, maybe from oil burning? Maybe from #4 running hotter because it's at the back of the engine? Maybe because?
27993595_10103204399359988_3021779298511098723_o.jpg
 
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Performance:(more information to come)

28515179_10103225845027698_9154587822726275007_o.jpg


Emissions testing from early 2017 with the same setup but the valves adjusted to .018/.020"(later checked at .020-.021" before resetting them to .015/.017" after passing DEQ)

26908087_10103172257462608_3686237854022147110_n.jpg
 
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HMMM!

27913395_10103207418883838_2119872513765423409_o.jpg


#4 is the old way of thinking and more tried and true Somender Singh groove variant(with various number of grooves on the larger quench surface). The swirl in the chamber supposedly goes opposite that groove towards the spark plug though, so options 2 and 3 may be better???

That being said, more modern OEM 2V heads look more like #1 with the quench pads even more gone, particularly on the exhaust side(tapered into the cylinder) and the spark plug unshrouded. I don't want to reduce my compression that much and make that large of a change on this iteration, though. This is more of a basic proof of concept attempt and then I'll go further with my big valve, ported head for the next setup.
Interesting info from Datsun L series heads:
"There are two main combustion chamber designs, commonly known as “open” and “closed,” or “peanut,” referencing the similarity of the closed-chamber shape to that of the typical peanut shell. Neither book referenced earlier really describes the differences in chamber design or why there are differences in the first place. Put simply, the open heads resulted in lower compression ratios. The open chamber design reduced hydrocarbon (HC) emissions for US offerings and did not do much else beneficial to the 510 enthusiast. With their lower compression the engines were tuned less aggressively and produced somewhat less emissions but as a result were less efficient and more susceptible to detonation.

The closed heads were designed with a good amount of quench area, the flat bottom of the cylinder head exposed to the combustion chamber. This quench area helps to add turbulence to the intake charge as the piston rises to TDC on the combustion stroke. This turbulence is beneficial because it helps to mix the air and fuel, providing a more homogeneous mixture and a stronger power stroke upon ignition. As typically the closed heads were fitted to engines with flat-top pistons to maximize the benefits of the closed-head design, there was minimal space between the top of the piston and the quench area (often just the thickness of the head gasket). The one downside of closed chambered heads is that the quench area can shield a small amount of the fuel from igniting, resulting in higher HC emissions. Thus the closed chambered heads were not selected for meeting USA emissions requirements."

https://en.wikipedia.org/wiki/Hemispherical_combustion_chamber
Modern design at the bottom, basically spark plug is more in the chamber instead of being shrouded, the chamber is open with smaller quench pads and everything is tapered up. None of these vertical walls that Volvo has in the combustion chamber design from the '40s or whatever.

V8 high flow head:
http://d23c3kq2pqf30j.cloudfront.net/wp-content/uploads/2012/05/bigchief-2_lg.jpg

Erland's work:
http://www.topplocksverkstan.se/fyrtaktsid6.html

Motordesign:
http://www.motordesign.se/images/Förbräningsrum.JPG

Etc..
 
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From what ive read on chamber readings you want it to be directed torwards the exhaust valve. Are you doing dimples on the clean chamber wall also?
Yeah the volvo chamber sucks for design.
Yes, directing towards the hot exhaust valve is suggested. I'm not doing anything with the chamber walls for now, just adding a single groove or three. Right now I'm leaning towards just doing a larger one on the main quench pad, thus leaving the rest of the chamber open to further modification in the future.
 
Seems like Option 2 might encourage swirl a little more than #3.

That said, what is this BS of doing a controlled test, before/after, numbers, etc.? It's hogwash around here, you know that. lol
/end TB mentality

I'm VERY curious to know what you find! I played with it years back when I swapped on a 530, seemed like it did help the detonation issue slightly, but that was purely SOTP impression. If you find something that does indeed help, I might go that route next time the 531 comes off.
 
Yeah!

Acutoff wheel to the cylinder head is a bit sketchy!!! That said, it gives a nice curved groove with no square edges. I then used a triangular file to open them up and will do a little more before it gets reinstalled. I'll also use rolled and/or folded emery cloth to smooth things a little further.

28337660_10103220166053408_7892997128424936681_o.jpg

28336076_10103220166043428_4046601287734700013_o.jpg

28234806_10103220166103308_6785916719308418832_o.jpg

28424026_10103220166068378_3625049787005035826_o.jpg
 
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Sorry the head is "upside down" in comparison to the previous pictures, but you get the idea. I may smooth the edges of the grooves a little bit more, but I'm basically done and just need to clean the head up for reassembly!

28423277_10103223992570038_148241856861376724_o.jpg

28424676_10103223992575028_9055937949272105501_o.jpg

28167963_10103223992560058_2791765774806574456_n.jpg
 
The grooving process, probably 2-3 hours? Taking my time, being cautious and anal as usual. The cutting with the cutoff wheel took like 5 minutes. The filing and being anal with it took the longest. And cleaning up here and there.
 
I've only made it through just over a tank of gas since I did the work and never got around to doing the back to back tests.

Initial thoughts are that I was not blown away by the result of my SINGLE groove experiment. Performance is basically unchanged(expected only an improvement around idle and maybe under 2000rpm), but there does seem to be improved detonation resistance. So at least it has that going for it.

Initially the idle was worse with reduced idle vacuum. It was acting as if I put in a larger camshaft. I'm pretty sure the valves are at about the same clearance as they were before, but during the downtime the buckets did get mixed up and I did have to reshim a couple. One intake might be a little tighter than before, but I doubt it's enough to make a difference. After the car learned through the tank of gas, it improved and the idle is now higher than before, MOST of the time. Sometimes it doesn't idle higher and it has low vacuum, other times it's comparable to before but the idle rpm is higher(indicating it's more efficient?). I didn't adjust the base idle setting on the throttle after doing the work. Low rpm performance doesn't feel much different, and may have even felt worse at first. I may or may not be able to lug the engine around more at really low rpm and low throttle openings with less interior rattling, but it hasn't been the larger difference I was hoping for.

As far as the detonation threshold goes, I used to have a lot of detonation when running the stock fuel tune and the advanced ignition timing. Even when it was cold out(<40? F) I had problems running that "tune" combination. I have continued driving the car in ambient temps over 65? F without issues. Maybe even as high as 75?. So, I would definitely call that an improvement!

My thoughts on the grooving experiment as a hole(for this round), are that doing ONE groove is not enough.

ONE groove may work ok with additional chamber modifications, such as reducing the squench pad near the spark plug and unshrouding the exhaust valve. Both of which reduce the need for grooves.



In a stock combustion chamber, I think TWO or THREE grooves is required for optimal results.



Nj?l's head is pictured above in post #758 and he had the desired results. Coupled with a K camshaft, he had a massively flat torque curve with good performance and no detonation until PAST MBT while running over 12:1 static compression in a B230. SEE HERE

I'm not sure what I'm going to do at this point. I may pull the head to add some more grooves, or I may just run it as is. Or I may pull the head, add some more grooves and take another mm off the head to bump the compression up some more with new valve stem seals as at least one is leaking some.
 
Took the car out for a beating at the track. Not fully prepared but ran the thing anyway(almost half a tank of gas, sub in trunk). 12 runs in an hour and a half...

Current setup: the very mild ported General Leif 530, single grooved, head shaved 0.032", 0.036" headgasket, M47, 3.73 rear end, custom LH/EZK chips, H cam, opened airbox, full exhaust including header(unnecessary and not helping at this power level) and 17" Tethys with 225/45 DWS 06 tires at full pressure.

WEST COAST BEST COAST NON-TURBO TIME(car 224C):
2.209 60’:
10.492 1/8 at 64.46mph
16.532 1/4 at 81.92mph

57104208_10103811597090868_23219104303284224_n.jpg


Lower times later this year if I get enough time to play with it!
 
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Yes, it could definitely benefit from one(shiny cylinder bores), but I'm not sure how that post about me drag racing makes it stand out? Hah
 
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