M10 cylinder heads-quench area

[Retoropak]

Lets talk m10 cylinder heads.

I have a 1.8 and e21 casting heads.
Both flows similarly with e21 a bit better on the exhaust side and 1.8 better on the intake side.

I noticed that the e21 have a spark plug located close to the quench area whereas 1.8 have the plug located on the opposite side of the quench.

How does it affect the flame propagation and combustion efficiency.

I am planning to run a lot of boost and want to pick the head that is less prone to detonation.




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[320iAman]

Your talking about the 2.0 Head vs 1.8 Head,,both are E21 Cylinder Heads, the stamps on the heads---e21--1.8i---4th cylinder intake side,, The Casting Numbers are different as well.

here is some threads on this with good info :

https://www.bimmerforums.com/forum/s...hts-Experinces

https://www.bimmerforums.com/forum/s...ng-M10-engines

https://www.bimmerforums.com/forum/s...pression-ratio

https://www.bimmerforums.com/forum/s...-best-M10-head

Randy

[Retoropak]

Correct.

I believe early e21 and some late 2002 heads had a e21 cast on the side of the head.





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[320iAman]

https://www.bimmerforums.com/forum/s...-best-M10-head

There is more to a good head than max air flow...

Each head has + and -.

1.8L casting head, MAY flow a little more than other heads due to the open chamber, I doubt it personally because these heads have canted valves that unshroud as they open because they move towards the center of the combustion chamber. They do come with the largest valves used in stock heads. Other heads use the same valves and some use smaller valves. These heads have injector hole in them. 1.8L pistons have a slight dome I believe (never had the head of my 1.8L so not positive) that won't work with other heads. Largest combustion chamber volume of all the m10 heads. Might be a great head with custom pistons with domes that match the combustion camber edge closely as often done with Harley Davidson Sportster Evo heads.

e21 casting head, Semi open chamber with one "quench pad". Quench pads promote turbulance and better combustion if the piston comes within .050" of the pad, any more clearance than that and the benifit deminishies greatly. Largest valves also. No injector holes. Won't work with 1.8L pistons-the dome will hit the quench pad. 2.0L engines with this head have a small dome.

121 casting, Closed chamber with two "quench pads" for even better combustion efficency but MAY not flow as well due to the closed chamber. I have not measured the valves from this head, they may be slightly smaller than the e21/1.8L valves but that's a pretty easy fix if you are redoing the head anyway. Personally, I would like to use this head myself, I think it would work great with a 92mm bore and flat top pistons.

These are 3 of the castings available that I have looked at, there are others out there also. Early 1600 and 2002 heads have smaller valves and closed chambers from what I have heard.

For info on head porting visit my page:

http://www.e21motorsports.com/kendan...er%20head.html

hope this helps some,
ken

Last edited by kdanielson; 11-17-2005 at 06:25 PM.

This I Like. 1.8L Casting Head

"Largest combustion chamber volume of all the m10 heads. Might be a great head with custom pistons with domes that match the combustion camber edge closely as often done with Harley Davidson Sportster Evo heads."



Randy

[Retoropak]

Thank you sir.

I am not really interested in the flow comparison. I totally agree with you that there is more than flow if it comes to good head design.

I am just getting ready to build my motor and the piston selection will depend on what head i will chose.

I have both 1.8 and 2.0 e21 heads available.

Let me digest the information you posted before i continue with discussion


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[autox320]

adding to this from the 02faq
121/121ti head: 58cc, 1972 and earlier

e12 head: 61cc, 1973 to 1975

e21 2.0 head: 60cc, 2002 and 320i, 1976 to 1979

1.8i head: 63cc, 320i and 318i 1980 to 1984


i used an older 79 casting 1.8i head on my build. Largest valves, sure has injector holes but plug them with jbweld etc it needed. Shave or mill down to take off what you need to tighten it up. Quench area imo should be .030-.035 to best fight detonation. I ended with chamber volume of 40cc using popup pistons. Yes I like the spark plug orientation of the 1.8 best especially if using boost.

[Retoropak]

I welded the injector holes in my 1.8 head. Took a lot of heat. My 200 amp welder was barely enough.




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[320iAman]

Here is another link with good info on quench.ect.

http://dsportmag.com/the-tech/cylind...orts-in-shape/


Lets see it-- Quench in a wedge-shaped combustion chamber is the area between the top of the piston and the flat portion of the combustion chamber.

782463.jpg Squish courtesy of HD Evo. squish.gif


More detail on squish/quench

https://www.hotrodders.com/forum/favo...+quench+squish Post #12
“In theory a flat top piston in a wedge chamber gives the best flame characteristics, that is fastest travel speed across the chamber with excellent squish and quench characteristics. Pop up domes get in the way of the flame front slowing it down which is compensated for with excessive ignition advance which then introduces problems with detonation and preignition combined with high fuel consumption and emissions. A circular dish piston reduces compression to that tolerable by the fuels used, these are typical of OEM low manufacturing cost solutions, these have poor squish and quench as too much of the piston crown is too far from the head's squish/quench deck to be effective. This results in a tendency to detonate and preignite combined with poor power and excessive fuel consumption. The D dish piston keeps the flat top's fast burn rate, eliminating the use of excessive advance and its problems; it brings the flat top's excellent squish and quench characteristics making for much greater detonation and preignition resistance, this is often referred to as mechanical octane. Like the flat top, it pushes the mixture into a pocket in front of the spark plug giving a more reliable light off and through burn for good power and lowest fuel consumption with that power. The dish is available in several volumes and with the deck clearance space, head gasket volume, and combustion chamber space is used to optimize the compression ratio that available fuels can tolerate.

“A digression to squish and quench. All engines hemi, pent, or wedge use this in some design form. It is an area where the piston and head close very closely together. With hemi's and pent's it's located around the outside diameter of the bore pushing the mixture toward the middle. On a wedge chamber it is found on the side opposite the sparkplug and valve pocket, pushing the mixture toward the sparkplug. These parts, or features of parts, perform two functions; one is squish the other is quench. They are separated by time in the cycle of compression to power. Squish happens first on compression as the flat surface of the piston closes toward the matching surface of the head. This ejects the mixture toward the sparkplug with great force both stirring the fuel and air together and increasing the density of the mixture directly in front of the spark plug. This both improves the chance of the plug lighting a burn (reduces miss and late fires), and it speeds the burn so cylinder pressure is optimized for piston position to press on the crankshaft with the greatest force possible (best power and use of the energy you pay for). At what is called the "late burn" part of the cycle is where detonation is like to occur. The temperatures and pressures ahead of the flame front are getting very high to where the remaining mixture is entering the "diesel" zone where it's happy to just blow up. To counter act this tendency is now the quench function of the close fitting parts of the combustion chamber. This is now a zone with a lot of surface area to volume, so it acts as a heat sink, delaying the point where the temperatures and pressures become so great that the mixture explodes instead of burns. These days of restricted octane fuels has made this feature very important as you can no longer just throw more Tetra-Ethyl-Lead at the problem.”


Randy

[autox320]

The old school repeat posts of M10 cc figures I wondered if they were counting the valves and plugs installed, but seems like bare chambers. I know mine was shaved a bunch which is common upping compression on the cheap, but they were 57cc.

Quench is an area often overlooked for motor builds, and does make a nice noticeable difference IMO. Lots of ways to get it close starting with pistons CH, but often need to adjust by headgasket (compressed thickness after fully torqued down) vs deck surface itself and compensate decking a bit. don't forget rod bearing clearance so take into account also if running super close. One word of caution is run the numbers if tighten up a bit cause does affect compression increasing it.

I'd have to run the numbers again but think ours actually came out to .035". Gasket compressed .063" minus pistons above deck .028". Makes for some zip and don't have to run crazy advanced timing. I mean was going for all it's worth limited on a NA powerplant sucking on a 2bbl downdraft carb


Nice head welding the ports but my first thought is the issue I had. Plugging the inside holes to profile the port itself. JBweld is knocked on a lot but the stuff works super doing this job, you just have to wait for it to cure then get in there with the sander.

[jrcook320]

I think it's generally better to have unshrowded valves, with the quench pad projecting squish toward the plug. My understanding of the science is very high level though. I think more important will be achieving the ideal .035"-.040" squish to maximize combustion efficiency.

I had my chambers cc'd (with spark plug) after the valves were done/head decked and they came in at 63cc on my 1.8i head. My head deck thickness is still above the min thickness spec.

I'd have to run the numbers again but think ours actually came out to .035". Gasket compressed .063" minus pistons above deck .028". Makes for some zip and don't have to run crazy advanced timing. I mean was going for all it's worth limited on a NA powerplant sucking on a 2bbl downdraft carb

Nice head welding the ports but my first thought is the issue I had. Plugging the inside holes to profile the port itself. JBweld is knocked on a lot but the stuff works super doing this job, you just have to wait for it to cure then get in there with the sander.

Stock pistons came up .028" above deck? Any idea how much the block had been decked?

I've read going tighter than .040" squish doesn't yield any improvement. I've been planning on aiming for .040", but may go closer to .035". Any thoughts on that?

I've also been indecisive on how to plug the injector holes, waffling between custom machined aluminum plugs, tapping the head for stainless bolts, or JB weld. Smooth port finish is a must either way. The JB looks impressive - withstands 3960 psi and 550*F - wow! I was most worried about temp, but if I get half that hot the motor's cooked anyway.

[Retoropak]

I pluged the holes using aluminum rod and welded it than used carbide burr to
Make it even with the port. Fit was a bit loose but i dont like the idea of jbweld crumbling and getting into the engine and messing with valves and turbine blades.


It looks like 1.8 head is preferred. I believe my 1.8 head has bad guides. I found some nice brass colored glitter in oil and the car smokes on decel but only after getting revs past 5 grand.

Does anybody know if Wiseco makes m10 pistons?

What other brands might have something for m10?

So far i saw IE and CP pistons. How about JE’s?


One last question. Would you bother with 144mm rods??


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[autox320]

I think it's generally better to have unshrowded valves, with the quench pad projecting squish toward the plug. My understanding of the science is very high level though. I think more important will be achieving the ideal .035"-.040" squish to maximize combustion efficiency.

I had my chambers cc'd (with spark plug) after the valves were done/head decked and they came in at 63cc on my 1.8i head. My head deck thickness is still above the min thickness spec.


Stock pistons came up .028" above deck? Any idea how much the block had been decked?

I've read going tighter than .040" squish doesn't yield any improvement. I've been planning on aiming for .040", but may go closer to .035". Any thoughts on that?

I've also been indecisive on how to plug the injector holes, waffling between custom machined aluminum plugs, tapping the head for stainless bolts, or JB weld. Smooth port finish is a must either way. The JB looks impressive - withstands 3960 psi and 550*F - wow! I was most worried about temp, but if I get half that hot the motor's cooked anyway.

Ok on the 63cc I just didn't do a stock head so had to wonder, just measured during the build of my doorstop. I'm sure my thickness is well below with a machinist death cross stamped on it.

Not stock pistons but during my build with the JE's I used. Decked my block .018" to reach .035" quench using a stock 2.3 95mm bore S14 gasket. I'd have to measure a stock 1.8 m10 but think I remember the piston was below deck maybe .010"? which is over .060" factory quench range. Just plugging figures into a compression calculator to give an idea using my parameters things can get interesting fast. Going from factory quench to what I used is difference between 11.8 - 13.3 compression. So food for thought, check numbers twice. IMO this is good though as the article and some point out it's less likely to have detonation and actually run on even less octane than you'd think. Less timing to get max output is also the advantage stated. All true. I know some use even tighter quench figures close to kissing the head but things grow with heat and .030 with steel rods etc would be my max since that's about where the dtm guys stopped and most do for hot motors. Just a side note but if using aluminum rods like some drag guys do imagine the stretch and you can't run this tight of quench or would always smack the head when hot.

I used plenty of JB weld in my build in the head and in the manifold. It's in the thread just after the paint job.

I pluged the holes using aluminum rod and welded it than used carbide burr to
Make it even with the port. Fit was a bit loose but i dont like the idea of jbweld crumbling and getting into the engine and messing with valves and turbine blades.


It looks like 1.8 head is preferred. I believe my 1.8 head has bad guides. I found some nice brass colored glitter in oil and the car smokes on decel but only after getting revs past 5 grand.

Does anybody know if Wiseco makes m10 pistons?

What other brands might have something for m10?

So far i saw IE and CP pistons. How about JE’s?


One last question. Would you bother with 144mm rods??


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Yes wiseco makes m10 pistons. So does Ross, CP, and JE. I've JE in my build ordered job code through RaceTep.
If you build from scratch and order pistons for a 144mm rod then yep I'd always choose the longer rod combo.

[Retoropak]

Specifying custom flat tops is easy how about the pistons to be used with 1.8 head? I guess to end up with lower compression and good squish the dome height would have to be altered or maybe valve reliefs cut to accommodate the squish and hotter cam.
I would like to get a custom set to be used with 144mm rods and 1.8 head with the 8.5-9:1 compression ratio.

When you order custom piston, how do you specify the dome size and shape? Should i go with the same dome shape as stock 1.8 piston and alter the dome height to get the proper compression ratio?


Edit:


I run quick calcs

Block height: 217.5mm
Rod lenght : 144mm
Stroke : 80mm
Compression height :34-34.2mm This number would have to be adjusted to get the proper squish
Head gasket: 1.5mm or 1.8mm How thick is the stock s14 gasket?
Deck height = squish = 0.035-0.04" = 0.89-1.0 mm

Now to get the proper compression ratio i will need to get the dome volume adjusted

Chamber volume = 63cc is it realy 63 on the 1.8 head
With the 92mm bore, .089 deck clearance, 1.5mm gasket and 10cc dome volume i would end up with 8.6:1
13cc domes would give me close to 9:1


What is the volume of the stock 1.8 piston domes?


Am i thinking correctly?

[autox320]

Specifying custom flat tops is easy how about the pistons to be used with 1.8 head? I guess to end up with lower compression and good squish the dome height would have to be altered or maybe valve reliefs cut to accommodate the squish and hotter cam.
I would like to get a custom set to be used with 144mm rods and 1.8 head with the 8.5-9:1 compression ratio.

When you order custom piston, how do you specify the dome size and shape? Should i go with the same dome shape as stock 1.8 piston and alter the dome height to get the proper compression ratio?


Edit:


I run quick calcs

Block height: 217.5mm
Rod lenght : 144mm
Stroke : 80mm
Compression height :34-34.2mm This number would have to be adjusted to get the proper squish
Head gasket: 1.5mm or 1.8mm How thick is the stock s14 gasket?
Deck height = squish = 0.035-0.04" = 0.89-1.0 mm

Now to get the proper compression ratio i will need to get the dome volume adjusted

Chamber volume = 63cc is it realy 63 on the 1.8 head
With the 92mm bore, .089 deck clearance, 1.5mm gasket and 10cc dome volume i would end up with 8.6:1
13cc domes would give me close to 9:1


What is the volume of the stock 1.8 piston domes?


Am i thinking correctly?

Stock S14 gaskets both 2.3 and 2.5 are 1.82mm. Compressed depending on torque values and method used can vary. I used the last updated torque specs 44 ft-lb, wait 15min, +33deg angle, run engine, then anytime cold or hot after engine temp reached +25deg angle. Compressed gasket can be measured under the edge of the head and a block pad or surface using a feeler gauge. Ours doing this is .063". As my chevy buddy would say. . . too much compression or quench just don't bolt the head down so tight

Factory 1.8 pistons have terrible quench(I may stick the deck gauge on a 1.8 tomorrow for giggles) but dome and factory comp is 8.8:1. As you see skimming the head decreasing chamber size, decking block tightening quench, you really have to plug numbers and order a bit under compression goals of pistons with the CH. If don't know for sure get close then deck the block a few thou to bring into exact spec. Different gaskets have different thickness also.

Just some old gaskets here in my garage. Used S14 2.3 supposed 93.4mm bore is more like 94.5mm and fire rings measured at .066 thick. A used 1.8 M10 gasket 89mm bore and .064" thick at the fire rings. Kind of useless but just gives ideas on how far and torque spec you use these figures can and do change.


I'd honestly just call Steve at Racetep or Jeff at Ireland. Your not the only one to request specs and they have "job" codes of pistons already spec'd for just about everything under the sun. Long rod big bore M10's have been done countless times as well as boosted builds.

If skim the head shrinking the chambers, I'd imagine the pistons will be near flat if not flat with valve reliefs being decreasing compression to compensate . If calling Tep they do make a "turbo" camshaft regrind I'd also recommend asking about.

[autox320]

Stock S14 gaskets both 2.3 and 2.5 are 1.82mm. Compressed depending on torque values and method used can vary. I used the last updated torque specs 44 ft-lb, wait 15min, +33deg angle, run engine, then anytime cold or hot after engine temp reached +25deg angle. Compressed gasket can be measured under the edge of the head and a block pad or surface using a feeler gauge. Ours doing this is .063". As my chevy buddy would say. . . too much compression or quench just don't bolt the head down so tight

Factory 1.8 pistons have terrible quench(I may stick the deck gauge on a 1.8 tomorrow for giggles) but dome and factory comp is 8.8:1. As you see skimming the head decreasing chamber size, decking block tightening quench, you really have to plug numbers and order a bit under compression goals of pistons with the CH. If don't know for sure get close then deck the block a few thou to bring into exact spec. Different gaskets have different thickness also.

Just some old gaskets here in my garage. Used S14 2.3 supposed 93.4mm bore is more like 94.5mm and fire rings measured at .066 thick. A used 1.8 M10 gasket 89mm bore and .064" thick at the fire rings. Kind of useless but just gives ideas on how far and torque spec you use these figures can and do change.


I'd honestly just call Steve at Racetep or Jeff at Ireland. Your not the only one to request specs and they have "job" codes of pistons already spec'd for just about everything under the sun. Long rod big bore M10's have been done countless times as well as boosted builds.

If skim the head shrinking the chambers, I'd imagine the pistons will be near flat if not flat with valve reliefs being decreasing compression to compensate . If calling Tep they do make a "turbo" camshaft regrind I'd also recommend asking about.

I just put a deck gauge on my old 1.8L short block sitting here next to the beer fridge. Cleaned off surfaces to get a good measure. Pistons are BELOW deck .005" so thats .069" quench with the gasket I had on it . . . and yup that's terrible

[320iAman]

Heres a good article on pistons--flat,dish and dome-types of piston tops and ring placement, ect. by JEpistons- Its a good read and quite current 3/2018..

http://blog.jepistons.com/dish-dome-...the-difference



Randy

[Retoropak]

Heres a good article on pistons--flat,dish and dome-types of piston tops and ring placement, ect. by JEpistons- Its a good read and quite current 3/2018..

http://blog.jepistons.com/dish-dome-...the-difference



Randy

Thank you its a very informative article.

It looks like there are some advantages to run flat tops which i agree with. I guess flat tops makes the distribution of fuel-air mix a bit more unjniform.

Also they stated that squish is not that important in the forced induction engines. I think i disagree with this. I believe squish will affect the speed of burn and will have a positive effect on the ping resistance.

With that said,do you think it would be more beneficial to run e21 head with flat tops and get a nice squish and also a bit higher compression 8.8-9:1(i will run e85). Or maybe stick to 1.8 head but have a bit lower compression 8.4:1.

Or maybe 1.8 with a slightly domed pistons and have a compression in the 9:1 range?

Do you think that half a point will make that much difference? I have fairly large turbo that wont boost until 4k.

I guess pistons will need to stick put of the hole around 0.3-0.5mm for that perfect squish

Thanks


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[OLD MAN]

The 10.5to1 CP racing pistons in our M20B25 have a bowl in them with a domed outer edge. Kinda opposite of what you think a higher compression piston would have.
CP said that .035" is the recommended min clearance piston to head, as their pistons grow some.

IMG_3091.jpg IMG_3105.jpg

[Retoropak]

The 10.5to1 CP racing pistons in our M20B25 have a blow in them with a domed outer edge. Kinda opposite of what you think a higher compression piston would have.
CP said that .035" is the recommended min clearance piston to head, as their pistons grow some.

IMG_3091.jpg IMG_3105.jpg

Looks like they stick out of the hole quite a bit.


It looks like there is a mix
of opinions weather squish has any effect on boosted engines.

Some state that a lot of squish will cause micro-detonation in the quench area, damaging the pistons, heads etc.
They also claim that no squish at all and keeping pistons in the bore is the best way for high boost.

The other group of people think that squish is beneficial to both on boost and off boost conditions. They state that the tight squish will make the motor less prone to ping. Also engine will not need as much timing since the burn rates are faster.

I just wonder if the pinging that the opponents of the tight squish experience is due to the excessive timing.


I kinda lean towards 0.04” squish since my turbo is fairly big and i could benefit from some extra oomph at low rpms.
I plan to rev it to 7-7.5k. Should i go for a bit more clearance to avoid contact?

Also to get that squish, pistons will have to stick out around 0.5-0.7mm out of the hole.

I plan to run fairly large amount of pressure. I will be shooting for 30psi or whatever the ping limit is on e85. I plan to max out my turbo (bw s252sxe). It flows close to 450whp worth of air.







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[autox320]

Looks like they stick out of the hole quite a bit.


It looks like there is a mix
of opinions weather squish has any effect on boosted engines.

Some state that a lot of squish will cause micro-detonation in the quench area, damaging the pistons, heads etc.
They also claim that no squish at all and keeping pistons in the bore is the best way for high boost.

The other group of people think that squish is beneficial to both on boost and off boost conditions. They state that the tight squish will make the motor less prone to ping. Also engine will not need as much timing since the burn rates are faster.

I just wonder if the pinging that the opponents of the tight squish experience is due to the excessive timing.


I kinda lean towards 0.04” squish since my turbo is fairly big and i could benefit from some extra oomph at low rpms.
I plan to rev it to 7-7.5k. Should i go for a bit more clearance to avoid contact?

Also to get that squish, pistons will have to stick out around 0.5-0.7mm out of the hole.

I plan to run fairly large amount of pressure. I will be shooting for 30psi or whatever the ping limit is on e85. I plan to max out my turbo (bw s252sxe). It flows close to 450whp worth of air.
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I think your plan is solid. Nah wouldn't worry about revs for quench. The PV clearance for cam choice and quench go hand in hand but just use a wheel to adjust. Your boosted so cam selection won't be as aggressive as NA. BTW if not using a turbo specific cam I know a guy used a schrick 292 with a T3/T4 hybrid with good results. He also had the LS1 chevy COP setup most use on MS etc.

[Retoropak]

I run ms2 with ls coils in wasted spark configuration. I might switch to full sequential spark and fuel once i upgrade my ecu.

I think i will use TEP turbo grind cam.





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