16v Bore And Stroke Info Please..

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16v Bore And Stroke Info Please..; inept at finding facts and figures
Topic Started: Wed Apr 2, 2008 10:33 am (272 Views)
zoomer46	Wed Apr 2, 2008 10:33 am Post #1
Member Posts: 1,296 Group: Members Member #509 Joined: September 2, 2006	can anyone find the bore and stroke for 2.3-16 2.5-16 2.5-16 evo1 2.5-16 evo2 oettinger16v 2.6,2.8 and who can supply forged pistons in the south? thanks in advance..



RobertE	Wed Apr 2, 2008 11:07 am Post #2
Serial victim... Posts: 7,829 Group: Members Member #1,403 Joined: June 13, 2007	2.3 - 16: Bore 95.5 Stroke 80.25 2.5 - 16: Bore 95.5 Stroke 87.20 2.5 Evo: Bore 97.3 Stroke 82.8 Oettinger: No idea! Mahle Powertrain in Northampton (who bought the Cosworth Engineering group when Cosworth was broken up) can supply original or custom made pistons. Phone number is 0870 157 3000



zoomer46	Wed Apr 2, 2008 11:14 am Post #3
Member Posts: 1,296 Group: Members Member #509 Joined: September 2, 2006	good work that man! and phone no.s too! i knew that bores on 2.3&2.5 are the same, and the evo's have shorter stroke and bigger bore ,but didnt know what the exact measurements were... seeing as we're here,what cc would the combo 0f the 2.5's crank and the bore of the evo's produce ?? i'm not so sure of my cm3's.



RobertE	Wed Apr 2, 2008 11:38 am Post #4
Serial victim... Posts: 7,829 Group: Members Member #1,403 Joined: June 13, 2007	2,594 cc, if I'm not mistaken! But, one could go further. Evo bore combined with 2.3 stroke would offer 2,387 cc, but think of the revs! You'd need an Evo block, 2.3 rods and some complicated pistons to achieve it and the bore/stroke ration would be radical for the time...



dave_irl	Wed Apr 2, 2008 11:54 am Post #5
Defector Posts: 8,735 Group: Moderator Member #6 Joined: November 2, 2005	a handy bore/stoke/capacity calculator use the second one down, and dont forget to change to 4 cylinders, then just click outside the boxes to calculate. I did all those calculations in college but 2 yrs of office job has killed my brain, that is much handier. For example now I am pleased to know that just a +1mm overbore on my new pistons now gives me 1837.5cc. So forgive me if I start calling her the one point eight four Anyway you should find that useful..



zoomer46	Wed Apr 2, 2008 12:07 pm Post #6
Member Posts: 1,296 Group: Members Member #509 Joined: September 2, 2006	spot on robertE, and a handy calculator too. now i see how oettinger got the 2.6 conv numbers , but the 2.8 version would of needed a 101mm bore. racing said that its a good strong thick block,so it seems that it must have enough beef to lose to be able to get the 2.8 oettinger had,not sure if its enough left if running a turbo on high boost.



zoomer46	Wed Apr 2, 2008 1:12 pm Post #7
Member Posts: 1,296 Group: Members Member #509 Joined: September 2, 2006	aha,found the thread from a while back,some oettinger figs found the 2.7 version too. http://www.baureihe201.de/W201/tuning.htm bore and stroke 2.3 - 16: Bore 95.5 Stroke 80.25 2.5 - 16: Bore 95.5 Stroke 87.20 2.5 Evo: Bore 97.3 Stroke 82.8 oettingers bore and stroke 2.6-16 : 95.5 x 90.5 =2593cc standard bore/larger stroke 2.7-16 : 95.5 x 94.5 =2708cc standard bore/ xlarge stroke 2.8-16 :(est) 97.3 x 94.5 =2811cc large bore / xlarge stroke out of interest , to make it a 3litre or 3.0-16(how odd sounding) it would need 3.0-16 : 99.9 x 94.5 =2963cc xlarge bore / xlarge stroke



zoomer46	Wed Apr 2, 2008 2:53 pm Post #8
Member Posts: 1,296 Group: Members Member #509 Joined: September 2, 2006	some oettinger pics,



hal9000	Wed Apr 2, 2008 4:55 pm Post #9
Member Posts: 679 Group: Members Member #365 Joined: June 25, 2006	There's a water jacket between the cylinders of the standard m102 block, and I think that you'll find that the maximum useable bore is probably around the 98mm mark. The only problem with that is that you've thinned the cylinder walls down enough that you can never re-bore or repair the block and you may need to replace it with every rebuild. Also, you've reduced the sealing area for the headgasket and you may run into problems with blown head gaskets. Also, if you are going to turbocharge the engine, having super thin cylinder walls is not very advisable. Differential heating and cooling will caust minor fluctuations in the cylinder wall and can lead to poor sealing and excessive blow by... Forced induction just makes that problem that much worse.



zoomer46	Thu Apr 3, 2008 3:25 pm Post #10
Member Posts: 1,296 Group: Members Member #509 Joined: September 2, 2006	thanks for the input hal, those are the sort of answers i was after,how far can you go and the complications that are caused.. i.e the head gasket contact area and bore limits but realistically,if you are turbo-ing the engine,it makes up for lots of cc's anyway, as can be seen by the old 80's f1 cars ,1500cc-1300bhp, so going for the cubes is no big deal when you got a good turbo system. the idea of a bigger bore turbo sounds nice,say a 2.7-16 so as not to push things too far,but i thought if you were going to the trouble of building an engine from the ground up,some new pistons and a rebore(or bigbore )may as well be done at the same time..



hal9000	Thu Apr 3, 2008 7:38 pm Post #11
Member Posts: 679 Group: Members Member #365 Joined: June 25, 2006	Don't take this the wrong way, but the accumulation of your recent questions really makes it look like you're trying to do everything to your engine (unless of course this is all academic... More power to you in that case!). Unless you have an unlimited budget or are a mechanical genius with access to your own full service machine shop, you're going to end up with an engine that doesn't do anything well because you've tried to re-invent the wheel. I can pretty much guarantee that if you decide to custom build a wholly experimental large displacement engine with exotic parts, untested cams, a non-oem Fuel injection system, an untested custom turbo system, etc etc..., several things will be likely to happen... 1) you'll spend a TON of money 2) you'll learn all the things you shouldn't have done, 3) you'll end up with a tuning and reliability nightmare 4) you probably won't be happy with the overall performance since you've built up the notion that this will be THE ENGINE, and not just another engine in a long line of them. Remember KISS (Keep it simple stupid). Don't try to build an F1 engine for your car. And especially don't try to do all the things you've been asking about all at once. Instead, just concentrate on one thing, and do it well. You'll be happier that way. (Takes a bow and steps down off soapbox) OK, now then. The old adage of "there's no replacement for displacement" doesn't really hold true for turbo engines at all. And if you do things right, it's not even necessarily true for NA engines. You're better off taking a relatively mild (stock) engine that's built to take all sorts of abuse, and turbocharging that. If you want more power, you just raise the pressure. If you start modifying the engine, you'll almost surely end up reducing the reliability, and you're not guaranteed to improve the power output at all. Also, remember that changing, bore, stroke, and rod length all affect how and where the engine develops power. If you're not careful, you can end up with a bottom end that's built for torque, and a top end that's built for high rpm power. In the end you'll get neither.



zoomer46	Thu Apr 3, 2008 9:28 pm Post #12
Member Posts: 1,296 Group: Members Member #509 Joined: September 2, 2006	it is mostly acedemic! and hyperthetical at times..(3.0-16 ) i like to suss out the limits first and work my way in from there, i know a long throw crank will not want to rev without insane mods to knifedge it and lighten it and make it from bloody billet :lol: but whatever i do it s always going to be an over-square engine.so at least i should achieve some sort of rev-ability. i do want to make the basic engine as un-restrictive as possible for when it comes to hopefully making some fairly big numbers,and i do want to go over the 400 barrier ,for which it seems the standard internals start potentially go awol. so i need in basic terms good crank, new conrods(a little shorter),forged pistons. then the head ,maybe some very slightly more aggressive cams and a touch of exhaust porting,no-more than that there tho, as for the boosting and fuelling side of things, i want to take it in stages, keep the t4 garrett for the mo,may get a different turbo with the same huff but better lower rpm boost, and definately change to a stand alone managemant system for the engine,maybe vems,pos motec who knows? may come down to price or who i can find and what they use and know how to use it? i want to fabricate an intake plenum as the standard one will get me so far but not enough,and am looking into how to ger equal air to all intakes from 1 hole,and get used throttle body to fit it. at the mo i am looking for an engine to use for mock ups, so if anyone knows of any... but i know for a fact that if i was trying to tune a n/a engine i would have absolutey no chance,as i'm sure it gets even more mathematical,and the gains are pretty pants from what i've seen,� for �. but i do have a plan,and i will keep asking questions ,cos i'm so bloody curious! i'm trying not to break new ground,but i also dont want to rip off other peoples ideas,but i do need them as some sort of benchmark to gauge ideas against. but luckily through yourself and the forum members ,i have built up a good amount of contacts to help me answer my newb type of questions, and i'm not scared to look like a wally asking them. its good to get a reality check though,which you've done nicely



hal9000	Thu Apr 3, 2008 10:03 pm Post #13
Member Posts: 679 Group: Members Member #365 Joined: June 25, 2006	By all means, rip off other peoples ideas whenever you can! There's nothing wrong with the tried and true approach. It'll probably save you time and money in the long run. Regarding your build plans. Shorter rods will also make the engine less rev happy. If you try to install a longer stroke crank, you'll have to be careful about that. Wether the engine is oversquare or not, those two items go hand in hand and will work against the natural ability of the 16V head to flow at high rpm, so even a small change could drastically affect the engine characteristics. Keep your rod ratio around 1.75:1 (about what it is now) if possible. The only two ways I know of to add a stroker crank and do that are to either find pistons with lower compression height, or add a deckplate (which due to the desigh of the M102 block will be a super expensive operation that you don't even want to entertain).



zoomer46	Fri Apr 4, 2008 4:20 pm Post #14
Member Posts: 1,296 Group: Members Member #509 Joined: September 2, 2006	so how does the length of the rod alter the power band other than the fact of lowering the compression ratio? and not too sure of the 1.75;1 thing ? what does this calculate against what? btw ,i'm not plannining on a longer throw crank,i was just curious how the big bore oettingers were configured.. not looking to take the revs over 8500rpm,the 10k's that jesper wants to get is possible but i think only with the special parts he has access to. but 8.5k is enough for most fast roadcars imho. also who is it possble to calculate how much to trim from a pistons crown to reach a specific comp ratio? am planning to replace the rods anyway,with shorter ones ,(jeretto had some specs for this)and stronger than oem obviously. pistons?well i may try to find some good 2.3 ones but seeing as they are a zillion years old now ,i may as well get some new ones . surely if the rods are replaced with only 2-3mm shorter ones that will not harm rev-ability?



hal9000	Fri Apr 4, 2008 5:14 pm Post #15
Member Posts: 679 Group: Members Member #365 Joined: June 25, 2006	The rod ratio is the center to center length of the connecting rod / the stroke of the crank. You want the rod to be about 1.75 times longer than the stroke for nearly every street driven engine. Race engines often have much higher or lower rod ratios, This is one of the tools that they use to "adjust" a car from track to track, but they also build engines to make power through a very narrow rpm range, which you can't do for any engine that you drive on the street. Here's an article to get you started: Rod ratio tutorial There are two main effects that rod length has on engine characteristics. Here my layman's explanation: 1) The longer the connecting rod, the lower the angle between the rod and the piston when the crankshaft is at 90 deg atdc. This means that all other things being the same, a longer connecting rod will transfer a greater percentage of the power generated in the combustion chamber to the crankshaft. It also means less angular loading on the bearings and longer bearing life. 2) The longer the connecting rod, the less time (measure time in degrees of engine rotation, not seconds here) the piston will remain motionless or nearly motionless at the top and bottom of the stroke. As the crankshaft makes its circle and the piston nears at tdc and bdc, the piston slows down, then stops (and reverses direction obviously). When the rod is longer in relation to the crankshaft throw, the rod doesn't have to go through as much angular displacement, so more of the crankshaft motion is translated into up/down motion at each end of the stroke. The stroke of the engine is the same, but the piston acceleration changes. This has a MASSIVE effect on how much fuel/air charge is drawn into the engine at high rpm. If the piston is moving sooner and faster, it will "pump" more charge into and out of the engine per stroke, and you'll develop more power. Basically, a longer rod will raise your dynamic compression.



hal9000	Fri Apr 4, 2008 5:18 pm Post #16
Member Posts: 679 Group: Members Member #365 Joined: June 25, 2006	If you do a search you can find the forumlas and calculators for compression ratio and rod length online, but it's pretty easy to figure out. If you do it by hand a few times, it will become obvious how you can figure out the amount of trimming you'd have to do to get a specific C:R 2-3mm might not make a huge effect, but do the math to find out. I'd consider 1.7:1 the absolute minimum rod ratio you want, and 1.8:1 a maximum, but that's as much personal preference as anything. This is the "butter zone" where you get the widest overall torque curve and rpm range on most engines. If you're building a street motor, that's what you want.



zoomer46	Sat Apr 5, 2008 4:46 pm Post #17
Member Posts: 1,296 Group: Members Member #509 Joined: September 2, 2006	so , if i wanted to change my compression, it would be better to do it via the piston crown? in your opinion , if i shortened the the conrod by 2.3mm ,like joretto, would that still keep me in the butter zone? i am going to try and work that out anyway tho.



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