Evo3 engine blueprints

Hey guys,

the DTM cranks are BALANCED at 1100 RPMs.

if you balance each component to very tight tolerances on their own, then in sum they should be quite ok. gr. A engine specs are for each component (rod, pistons, crank..)   you CAN then dynamic balance the full assembly, but if you ever change the type of clutch/flywheel, it is no better than not balancing the entire assembly -- and it could be detrimental if not all of the components were well balanced each for themselves.  in fact, if I knew my assembly required a further correction as a whole, then when swapping in a new component like a flywheel (which will be balanced on its own), id still check the entire balance again.  do you realize what this entails?  lets say you decide to go from a sachs sport clutch to a tilton or AP twin disc carbon clutch with magnesium flywheel. That would represent a large change in inertia that is seen at the end of the crank.

the second issue to consider here is that I dont trust just anyone on a crank or a balancing machine. BMW has the best machines available, I dont know if your local garage buddy down the street has the same.  When someone starts taking metal off a crank, Im also leary.  Not every Joe knows what the stress inside the crank is. Even engineers dont know it. Thats why they model it, then they run numerous tests. This is something that can effect longevity. Although even the factories have take the inner 2 counter weights OFF ENTIRELY on a 4 cylinder crank. They got it balanced. But it is meant for racing where longevity is not the same issue as on street. As long as we are clear on that, no problem.  With this technique you can get a S14 crank down to sub 14 kg easily enough.  On my own (street) engine, I decided not to go down this route. I still currently have no CF clutch installed (yet), I figure the latter make a huge change in revability (think motorbike), coupled with a magnesium clutch this should be more than necessary to make my engine rev happy -- although it is ALREADY rev happy.  I voluntarily limit it to 8500 rpm. It is built to handle 9600 rpm. I would have to misshift and hit > 10000 rpm before I get piston-valve collisions.

I have a few pictures I got from the internet on the S14 head. whoever it was that wants it email me. They are technical drawings.

I also have some gr. A specs -- motorsport always gives tolerances for their measurments.  I believe (from memory) the head chamber is 43 + 0.5 cc.  I hope you know how to CC more accurate than .5 CC :) If you are getting into this, you are going to need every single spec, every tolerance, and you will have to measure every chamber, every piston, every rod, every fuel injector, the volume of ever intake and exhaust port, piston to valve clearance on every cylinder, valve heights on every valve, valve spring rates and shim stack on every valve, weights of pistons, weights of your shim under buckets, your valve weights, measuremetns of each cam journal etc. etc.  (OK relax: atleast for a few parts, like the cams, if they are motorsport cams you get documented measurements for the cams -- every single journal to very high tolerances)

This is what I believe they mean in the USA when you read "blue printing".  If you do it all -- you will fill about 25-30 pages of engine build charts and spend a lot of time. Some people just measure a SINGLE cylinder and ASSUME the others are the same, as when they dial in cams and just check clearance to the piston on 1 cylinder  -- they also say they have blue printed engines. Thats not really correct (but does not mean their engines not well built anyway, they are just not "blue printed" to the full extent).

So, I hope you know what you are getting into here :)  I can help you with the gr. A stuff, I just need to find it laying around somewhere here.

But BEFORE you get all excited about this -- remember this is also a typical MARKETING/SALES point to pull more money out of your pocket.  The pros really to build top engines like this, but they are also very expensive build ups. They also x-ray engine blocks. Ask your local tuner if he has this capability...  You need to have a very honest builder to work with and have full trust that the work you are asking for is actually being done, and done right with all the proper machines at their disposal. Machines cost money which will reflect itself in the price of the work you are charged. If the shop has no machines, well, they cant do the work, they out source it.  You should be able to drop into the shop without notice to find someone working on your parts and seeing top notch work being performed. There are VERY FEW people at the "grass roots level" I trust with this sort of stuff; the people I do trust know me very well and we have a long working relationship and when I have parts machined, I can stand right there and watch while its done (which I do). Famous companies can probably do the work (like Randlinger/Quintec in Germany, or some of your famous shops in England) -- but they also have nice prices.  There are Randlinger hillclimb S14 engines that cost 100000 DM back in the day (49000 euro).  Unfortunately, with engine work you outsource to various shops, its very hard to say later who did what wrong when something goes wrong. This is part of the reason why a builder should be able (==knowledgeable) to understand all the processes and steps involved -- and check them.  Some builders do this, some just CLAIM to do this.  This is time intensive work, so it also costs a bit of money for all this "blue printing" and checking and double checking. We often read about various engine build prices, but really you can just read a build-spec sheet and know exactly what kind of work went into it unless you did it yourself.

BTW, on my engine things like rods and pistons were balanced down to 0 on the scale which had a 0.001 g accuracy. But gr. A does not demand this, and there is also a spec for the rods with the pistons which must be met (I dont remember at moment but can look it up). Getting piston mass perfect is also a bit of a TRADEOFF with compression ratio if you measure any chamber volume differences, or your crank has a slightly longer stroke on one cylinder than another. you can take mass of the underside of the pistons, or on the top at the dome, but the dome is adjusted to get the desired compression ratio. You can go for perfect comression ration on all pistons, or perfect mass on all pistons. doesnt really make sense does it? thats why we have tolerances.  as a result of this, we are also going to see varying intake flow into each cylinder, and injectors are normally rated to 3% unless you have some specially matched ones (gr. A balanced injectors that are matched run 200 euro a piece). Motorsport cam lifts have up to 0.05 (maximum) toleranc on lift though they are usually significantly below this number.

The end result is: you can play the "tight tolerances" game to get as much power as possible, but it does cost time and money. and I will reiterate that I truly believe a lot of shops are not HONEST and tell you a bunch of crap because it sounds good and it pulls the money out of your pocket. So be careful. When you find the right people who know how to do this kind of work, you will know.

John

Hi John, Some good reading!

I'm not after a fully blown racing engine, but a nice, strong, powerfull standard engine. I want to keep this car standard, but to an extremely good standard. I heard the Evo3 in standard trim struggles to make all the 238BHP BMW say it does, so I want to have a go at getting the full 238, or more???? just with ballancing, blueprinting and carefull assembly.

I don't know much about the measurements or capacities, tolerances of the S14 2.5 or the 2.3 either, and have struggled to find any solid technical information and dimensions of all the components.

Any help in this area would be much appreciated.

Are you John with the red Evo3 at the ring? Thats a superb car you have if it is you, and I would love a passenger ride - er...if its on offer ofcourse?

Paul.

Uwe, he wont find much in the TIS. But can find in the gr. A shop manual. e.g. the roughness of the hone is specified in that and much more.

gr. A engine are blueprinted.  but, BMW motorsport "selects" parts. e.g. if you buy bearings they are closer than if you get them from BMW. If you buy their injectors they are a balanced set. If you buy gr A valves they all weigh the same within tight tolerance (I know because I measured them). If you buy valve spring the spring rates are matched.

anyway, back in the day BMW motorsport got 220 hp out of its gr. N engines  when the stock one for the street was only making 200 hp. not all the parts were from normal BMW parts supply, but some special motorsport race parts (like the block which was honed differently)

John

Uwe, I dont know. I thought we were just talking aber a theoretical 84 mm crank in the evo3 block with standard 95.0 mm pistons. rod length 144 mm the same in either case. In such case, we should see around 9.8:1.

I do not see a reason to install an 84 mm crank in the evo3 block.  evo3 cranks are cheaper than 2.3l cranks (or atleast when I checked some time ago).

Roops, I have no experience with Kempower. They may be good. I have to say, since I am in Munich I have access to pretty good machinists, e.g. people that worked for BMW Motorsport for 30 years and can still get a head done like they were done for DTM, because he is one of the SAME guys that worked on them. If I want my block bores+honed, then I have the guy in Bad Tolz that did DTM blocks, if I need an exhaust system, I have 2 people in Bad Tolz that make exhausts. etc.

John

UweM3 wrote: SHEPSM3 wrote: Anyone know what my compression ratio would be with a 2.3 crank fitted to my 2.5 engine? I have been trying to work it out, but its doing my head in! with which pistons?????

Uwe, 2.5ltr pistons. My engine is definately an evo3 engine, except when the engine was rebuilt by a previous owner, they fitted the 2.3 crank. All other parts, ie piston rings, inlet and exhaust valve were all for the 2.5ltr. There is an invoice in the file I have a couple of days after the crank was supplied which is for the nut to hold the front pulley on. IDIOTS! calm!

1.5mm down the bore at TDC must mean alot of compression pressure lost I would have thought. I have still yet to dyno the car to see what power it is putting out with that crank. But it feels alot more powerfull than the 160 it had when I got it!