duratec 2.0 turbo motor into my new project mx3.

[seawulff]

well mpg is a little more complicated than that. engine efficiency to intake tune to motor tune to transmission gearing. all of which play a role and have to be matched to each other and even many other things. as far as cost, its not anymore expensive to build a duratec then a bp motor. i got a duratec for 200 bucks but the nice thing is its a new motor so i dont have to do any machining to the crank or cylinder walls. as far as making it fit, its pretty easy and not really any more expensive then a bp. parts are very prevalent just like the bp and pretty much the same price. now the big difference is head flow and efficiency. the duratec has a way more efficient head design and efficiency then the bp simply cause its newer tech. there isnt really any real need for porting on the duratec either. as far as bearings, higher load on the bearings on a reg basis equals faster wear. i can build and tune it for 400s but keep the boost down for my daily driving so im not tearing my motor up faster. o and the duratec has bigger bearings equaling more surface area to recieve the load. this gives more longevity to the bearing life. only thing that sucks about the duratec is it does not have piston oil injectors but i am getting it machined for a couple hundred bucks so not a big deal. only thing better i could think of is the direct injection motor but then you are talking a lot of money. the duratec is one of the best motors on the market as of today. all motors are not created equal. i will still be building a b6 motor car because i have two mx3s and i am curious how much fuel efficiency i can get out of a b6 motor. morbid curiosity.

[300zxrb26dett]

as far as bearings, higher load on the bearings on a reg basis equals faster wear. i can build and tune it for 400s but keep the boost down for my daily driving so im not tearing my motor up faster. o and the duratec has bigger bearings equaling more surface area to recieve the load. this gives more longevity to the bearing life.

Oh boy, just for curiosity, where have you been getting this info?

If this was a roller bearing or a similar type that actually made physical contact with the surface it rides on then yes I would agree with you. BUT, an engine bearing does not make physical contact with a crank journal, and if it does, it finished. As long as you have oil pressure, the bearing will be fine no matter how much power you make.

Let me ask you a simple question-------Does liquid compress? (please I am only asking the OP on this one. I dont need anyone else to answer.)

[seawulff]

well then, i respond with a simple question. what wears out bearings. they do not last forever. especial in high output motors.

[seawulff]

The answer is yes, you can compress a liquid, or almost any material. However, it requires a great deal of pressure to accomplish a little compression.

[Ryan]

You guys are arguing semantics...

Yes, how much power you make affects the bearings differently. Do you think the force is just magically absorbed by the oil? It is still transferred to the bearing, no matter if there was a micron of oil, or a litre of oil between them. The loading and unloading causes stress, fatigue, and wear (oil contains small metal particles that do 90% of the damage, and these can't be caught by the filter)

[300zxrb26dett]

Yes thats right liquid does compress, but the amount of pressure that occurs inside the engine is not enough to compress your oil and cause wear..

Your wear comes from cold starts, when there is little to no oil pressure, and the engine computer right away causes the idle to be high. The weight of the crank can squeeze the oil out, and the small fraction of a second at startup is when the wear occurs. One of the other reasons you get bearing wear is dirty oil or maybe the oil is new but some particles got inside when you changed the oil or valve cover gasket, or did not keep every thing clean when you rebuilt the engine. Most of the wear occurs from these 2 things.

The other reasons can be-- improper oil clearances, improperly installed bearings, and what your referring to with a "high output engine" the stretching and compressing of the rod causing the big end to slightly change shape, thus changing the oil clearances and causing your wear. Although this type of wear is more pronounced with a high revving engine then a lower revving one, which is the reason why you should have little concern for having to change your engine bearings at 30k because of your "high output" engine that is not seeing racing duty.

Ryan I dont know what your talking about with the load transferred to the bearing?? According to what your saying the bearing should fail from flexing and stress cracking from all the pounding its getting. Show me a bearing that has failed from stress and fatigue. The bearing is designed to flex, and yes I agree that how much power you make effects bearing wear, but not to the degree the OP is talking about.

[Ryan]

You're right, the OP shouldn't be going through bearings every 30k on a DD, even at 300-400hp, as the car will only put down whatever it puts down at 1/4 throttle at sub 3k anyway.

But you don't seem to understand that the bearing sees 100% of the stress and strain caused by the whole ICE cycle. There is no magic way to transfer the force from the conrod to the crank, it MUST go through the bearing, and all stress and strain causes fatigue and wear, no matter which way you slice it. More power will cause more stress and strain and wear, but, you're right, not for a biannual rebuild.

Yes, you're right, cold starts play a big part, but then again, that is not the only factor. As is the case with the rest of your arguments, you're right, but those are not the only factors, perhaps only the plurality.

Simple mechanics of materials, everything strains, everything fatigues, and everything eventually fails. Faster under harsher conditions and stress, and probably fastest in this case in an poor oiling situation like you were talking about, metal on metal at 7k, causing enough heat to weld the bearing to the crank and cause some obvious damage...

[seawulff]

the 30k miles thing was just a hypothetical number i threw out there. My buddy's Honda has to be replaced every 30k or so but he revs to 14k. im just saying, most likely, mid 300s should be a good area of hp for DD. the more power you are capable of dumping out the faster the internals will wear out IF YOU USE IT. now i get it, if your just cruising than it doesnt matter what the power potential is. i guess i just fig that was a given understanding. the point is i am going to be dumping on the throttle fairly often zipping around town and if i have the motor in a lower max output range, it will last longer. i can turn the boost up for racing and what not which is what i am trying to explain. ultimately i am limiting myself so i wear the motor out slower. ill prob invest in an electronic boost controller so i can adjust on the fly. thing is, if you have information that you think i should know or could use, then thank you for your help, but lets not spend our time being derogatory and trying to make someone feel stupid. there is no benefit for anyone in that.

[seawulff]

i had a question for those of you who have solid knowledge about porting heads. i read that it is especially useful to port older heads because the head flow and consistences were not quite as on key as they are now a days. my question is to the fuel efficiency effect of porting a head. does it affect your mpg. seems like there is a lot going on with velocity and fuel atomization that widening the ports would give less velocity so ?less? atomization. im not so sure but am very interested in anyone's thoughts or facts.

[Ryan]

its much much more complicated than that.

Generally, unless you have the time and money for flowbench time and pro headwork, don't touch it. It isn't the place on the motor where the "It probably couldn't hurt" doesn't apply. Changing the port volume or even shape can cause drivability issues if you don't know what you're doing, and make your powerband very spotty.

[300zxrb26dett]

Fair enough, I wasnt trying to make anyone feel stupid, but i know thats how i come across sometimes.

[seawulff]

update: I decided to sell all my other project cars first cause i need to get rid of this clutter. Im about finished with that. So for the sake of keeping with the MAZDA name, i am going to use the MZR duratec motor instead of the focus duratec, and a mazdaspeed3 6speed trans. its about a 1000 for the trans and i found a full MZR motor for 500. i can get a harness and ecu for nothing. (my friend works at a HUGE wrecking yard). I also met up with a guy who graduated from wyotech doing performance auto, and he is going to help me with the project. so first i will be starting on the body work and prep for paint next week, and should have all my other vehicles sold in 2 to 3 weeks at which time i start the install of the MZR. Im pretty sure i will have the coolest mx around. i picked up some suspension stuff already and am piling up parts for the build lol.

[tehbrookzorz]

Wait... Wouldn't spreading force over a greater surface area reduce the pressure experienced by any one part of the surface area? Also, less lateral stress is experienced by the bearing. Otherwise, we'd be using bearings the width of a paperclip. Not going to happen.

[Ryan]

Not sure how this is related.... but yes.

Stress is measured in force/area.... aka pressure.

[seawulff]

in response to tehbrookzorz, that was exactly my point in the beginning. pressure spread over larger surface area means less pressure per square area and more heat dissipation.