Building a Turbo Duratec. 2.0 or 2.3?
Posted by espacef1fan
Kirk Coughlin Professional Moderator Location: Saint Paul, MN Join Date: 01/08/2006 Age: Possibly Wise Posts: 493 Rally Car: Dreaming of escorts and xrats |
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John Vanlandingham Mega Moderator Location: Ford Asylum, Sleezattle, WA Join Date: 12/20/2005 Age: Fossilized Posts: 14,152 Rally Car: Saab 96 V4 |
Know those flat areas on ahead in the chamber? 
They are relatively speaking much cooler than what's happening in the chamber---which is very hot when the gas burns. If we bring the pistons up as close as we dare, flush or slightly out of the deck surface, and have say .030" to .036", the piston crown edge is close to the quench areas and doesn't get the full effect of all the fire-n-shit happening in the chamber.. If its cooler, it doesn't lose strength and bend from all the pressure on the crown ---the pressure big enough to move the car----and pinch the top ring.. Look at the piston in cross section: 
The top groove leaves an overhanging bit that--in thos case is real thick cause this is some sick turbo diesel, but in modern cars is just asking to push down and pinch the ring---there's only .002 clearence.... So anything we can do to keep the edge cool means the piston lives better.. Getting the piston that close also smooshes all the gasses into the chamber where is burns rapidly...not hanging out round the cylinder walls or a big gap tween head and crown like oh, say 1.7 Ford V4 for USA which ---to meet EPA NOX requirements long before Catalytic confusers-----had, like everybody in 71 o so, 8:1 comp. Ford lowered compression by lopping 2mm off the crown leving piston down the bore 2mm+ 1 mm gasket thickness.. Those fawkers pinged their brains out Bringing piston UP till it sticks out .004"/ 0,1mm and having a less than .0404/ 1mm gasket means I can do about 11.3:1 comp on 92 okt without ping--and a cast iron head.. Happily, the V4 has a compact combustion chamber and generous quench pads... Everybody is not so lucky: 22R Toiletta: 
Old Misterbitchi G32B like old Colts: Nissan Z-20/Z-22 heads--see a trend going on? 
Al least old L16 had a bit of quench: 
But look at a modern Chevy V8 pushrod head: 
The distance thing is "how many mm is the bore cause if its 81-86mm in X time the flame has burned completely and makes the heat and pressure enough to scoot the car along pretty good..... But in X time in a 90 or 92 or 96mm bore, when its gone 81 or 86mm there's lots of heat and lots of pressure but it still has a way to go to burn everything, and we wanna burn.. Problem is temp is so high after say 86mm that the remaining charge wants to pop off on its own..Detonation... Note the bore size on a shit-ton of modern 2.0 motors that have done well in last 20 years. A huge pile are 86 x 86: GM 2.0 XE; Ford F2 "RS2000" motor, Toyota 3GSET, Nissan SR20DE; the new Evo 10 motor, the new Subie 2.0 motor in the Toyoburu thing , some---Misterbitchy 4G62 , some of the Renault/Peugeot and Citroen motors have been 85 x 90ish--and Ford themsellves reduced bore in the Fuckki WRC cars from 87.5mm to 85--and made it back up with stroke... Contrast that with old 60s designs like the 1.5 and 1.7 V4s, and Saab OHC and DOHC motors at 90mm, Oldpiles at 93 for USA or 95.2 for 2.0 Ascona/Manta, Volvo at 92 for B21 or 96 for B23, Pintoid at 90,8mm so also YB Cossie likewise.. Sub-a-rat EJ20 at 92 well there more room for valves but harder to get the real bang out of them (you have to do everything right) without detonation.. More later. I gotta go make chips fly. John Vanlandingham Sleezattle, WA, USA Vive le Prole-le-ralliat www.rallyrace.net/jvab CALL +1 206 431-9696 Remember! Pacific Standard Time is 3 hours behind Eastern Standard Time. Edited 1 time(s). Last edit at 02/10/2013 02:17PM by john vanlandingham. |
Kirk Coughlin Professional Moderator Location: Saint Paul, MN Join Date: 01/08/2006 Age: Possibly Wise Posts: 493 Rally Car: Dreaming of escorts and xrats |
This is the kind of info I've missed. I should have come back sooner.
So how many cylinder heads have some kind of cooling passages on them... better still, Why don't they come standard with heat sinks on them? Kirk Coughlin Woodbury, MN and River Falls, WI Quemadmodum gladius neminem occidit, occidentis telum est. |
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