UCP Supercar II: Engine Department.

[hightower99]

In my opinion it has to be naturally aspirated all the way.

the sound, the delivery, no turbo/super charger can match it

FI = sledgehammer
NA = scalpel

A low pressure turbo designed for early boost would essentially give the feeling of a larger NA engine, with the added bonus of killing some of the exhaust noise and alot of heat so a less restrictive more acurately toned exhaust can be created.

so in this case

low pressure quick boost FI = Sharper better scalpel

[jediali]

VC idea 1: I am not sure what you mean I have considered what happens when the cam gears are further away or closer to the crankshaft. The main problem is how to maintain a set distance in three locations, from crank to first cam gear, between the two cam gears, and lastly between the last cam gear and the crank. As long as the length of chain is maintained in those areas then the timing isn't affected at all by being closer or farther from the crankshaft. I made a mistake I meant to say that two tension gears are needed per pair of cam gears. Basically extra slack is run between the crank and the first and last cam gear. When the system is set for high compression (i.e. the cam gears are close to the crank) then the tension gear have to take up all the slack. As the head moves up and the cam gears travel further from the crank then the tension gears take up less slack and the timing is unchanged.

VC idea 2: Yes it sounds complicated but I have already simplified the total system somewhat. I plan on the top faces of the pistons being the cup that fits over the piston body which is directly connected to the connecting rod conventionaly. I have tried to minimise the volume of oil needed to move the piston face without reducing the working surface area too much. I have also been thinking of combining both systems because this will allow me to half the distance traveled by both systems and therefore make the total solution more realiable, efficient, safer, and possibly lighter. I am looking at an operating range stretching from 16:1 down to 9:1 compression ratio.

Jediali: I do like your system. I hope that as you refine it you strive to make it as light as possible (judging from the pictures they look really heavy) Also wouldn't it be great if we could control intake and exhaust lift seperatly? and what about being able to control the lift of each intake valve in relation to each other (i.e. in one cylinder one of the two intake valves opens with medium lift but the other only lifts abit), this would help achieve the swirl we will need to get good combustion with lean fueling. I hope that you can get a good operating range (I was thinking from 0mm to something like 10-12mm). I can't wait to see what you get once you have refined it. I think you might want to consider where the air is going to go if you try filling the whole thing with oil to get max lift.

vc1:
http://www.autozine.org/technical_sc...gine_4.htm#SVC
ok your probably right.
vc2:
what about piston shape as it cools/heats

my idea could be lighter if we just used an air spring instead. yes valves are controlled by group of intake or exhaust.and a intake pair could be staggered to create swirl. The constant volume of low pressure air in the resevoir gets compressed to a small volume by the oil before (full lift) or by the cam lobe (more work done by engine)

[jediali]

A low pressure turbo designed for early boost would essentially give the feeling of a larger NA engine, with the added bonus of killing some of the exhaust noise and alot of heat so a less restrictive more acurately toned exhaust can be created.

so in this case

low pressure quick boost FI = Sharper better scalpel

you might also kill the vocal delight as well as the volume of the exhaust noise, however it would be useful to have a freere exhaust. The 335i doesnt sound "as good as" M3. Still with you though.

[hightower99]

VC1: thanks but I am still refining the idea...

VC2: Yeah that has been one point that has been bugging me. I am assuming that with a good deal of oil flowing through the piston (at least in relation to what is normally sprayed on the back) that the piston temperature would be somewhat moderated. However I will need to design the cup to be fairly strong in it's own right (which actually was one of the benefits of lowering the volume of oil used). Also so far the designs I am thinking of all have guided joints that help positively locate the piston face (don't want it to start rotating in relation to the cylinder centre).

Glad to hear that your system is capable

you might also kill the vocal delight as well as the volume of the exhaust noise, however it would be useful to have a freere exhaust. The 335i doesnt sound "as good as" M3. Still with you though.

Volume will be down due to the exhuast being colder and having less kinetic energy. But that doesn't mean that we can't tone the exhaust to those pleasing frequencies actually since the SoS will be lower it would be easier to tone the exhaust

Hahaha yes the M3 does sound better but that is mostly because the M3 has a big V8 and a sports exhaust while the (330i twin turbo I6) which is the one I think you are referring to sounds more docile because it has a long exhaust designed to maximise the turbo response.

Still the 330i doesn't sound half bad does it?

[jediali]

VC1: thanks but I am still refining the idea...

VC2: Yeah that has been one point that has been bugging me. I am assuming that with a good deal of oil flowing through the piston (at least in relation to what is normally sprayed on the back) that the piston temperature would be somewhat moderated. However I will need to design the cup to be fairly strong in it's own right (which actually was one of the benefits of lowering the volume of oil used). Also so far the designs I am thinking of all have guided joints that help positively locate the piston face (don't want it to start rotating in relation to the cylinder centre).

Glad to hear that your system is capable


Volume will be down due to the exhuast being colder and having less kinetic energy. But that doesn't mean that we can't tone the exhaust to those pleasing frequencies actually since the SoS will be lower it would be easier to tone the exhaust

Hahaha yes the M3 does sound better but that is mostly because the M3 has a big V8 and a sports exhaust while the (330i twin turbo I6) which is the one I think you are referring to sounds more docile because it has a long exhaust designed to maximise the turbo response.

Still the 330i doesn't sound half bad does it?

good to see your ideas progressing. I actually meant the 343 hp M3 i6 vs the LPT DI i6 in 335i

[fpv_gtho]

Regarding the engine layout, im a fan of the typical NA V12. The V12 especially for smoothness. Afterall, its a GT we're going after and IMO the packaging benefits of a W engine may be best suited for a more raunchy supercar.

[hightower99]

good to see your ideas progressing. I actually meant the 343 hp M3 i6 vs the LPT DI i6 in 335i

Ok in that case I would have to agree with you to.

E46 M3s have one of the greatest engine sounds ever.

But the 335i doesn't sound bad at all I might add.

[hightower99]

Regarding the engine layout, im a fan of the typical NA V12. The V12 especially for smoothness. Afterall, its a GT we're going after and IMO the packaging benefits of a W engine may be best suited for a more raunchy supercar.

May I ask why you think the compactness of a W configuration is suited to a more raunchy supercar?

A W12 is almost just as balanced as a V12 so much so that you would only notice it if you had your hand on it...

[fpv_gtho]

A GT can afford more liberties in its packaging, like a longer engine in this case if it means it'll evoke more passion in the buyers, or it'll simply sound better. A supercar however will be all about performance, so a W layout which can package the engine tighter, will be better appreciated and utilised. I know youve got your mind set on a mid engined GT here, in which case a W layout would ensure more luggage room and perhaps not influence the styling as much as had the car needed to accomodate a V engine.

[hightower99]

A GT can afford more liberties in its packaging, like a longer engine in this case if it means it'll evoke more passion in the buyers, or it'll simply sound better. A supercar however will be all about performance, so a W layout which can package the engine tighter, will be better appreciated and utilised. I know youve got your mind set on a mid engined GT here, in which case a W layout would ensure more luggage room and perhaps not influence the styling as much as had the car needed to accomodate a V engine.

Weird I am thinking almost exactly the opposit.

Basically I don't think anyone would want a W engine in a full out supercar for track racing because of the potential cooling problems, slight increase in vibration, and thin connecting rods.

In a supercar i wouldn't care much about luggage space. and I wouldn't mind having to drive it in a slightly cramped cabin. I would appreciate the smoother engine, lack of cooling problem and stronger connecting rods. As well as the fact that a V12 is slightly lower and would allow me to make the car lower aswell.

I think that in a GT where confort is a priority and a certain amount of luggage space is needed that a W configuration suites the needs better...

IMOA

[jediali]

Ok in that case I would have to agree with you to.

E46 M3s have one of the greatest engine sounds ever.

But the 335i doesn't sound bad at all I might add.

thats why i used quatotation "not as good as"...who would turn down a 335i?

[henk4]

thats why i used quatotation "not as good as"...who would turn down a 335i?

for your info: BMW has an extensive "sound" department, where every engine is tuned to make the sound that the expected clientele likes to hear. (also the sound of closing doors and whatever sound is carefully thought about). So when you think that an M3 sounds better, the BMW people have done their job perfectly. I am sure that they make a 335i sound like an M3 if they wanted to.

[derekthetree]

let's use the Radical V8 then, 2.6 litres...

pff, that's just massive. lets strap a few turbos on this baby



while FI does allow you to have a smaller capacity engine, the cooling requirements necessitate more room...

[jediali]

for your info: BMW has an extensive "sound" department, where every engine is tuned to make the sound that the expected clientele likes to hear. (also the sound of closing doors and whatever sound is carefully thought about). So when you think that an M3 sounds better, the BMW people have done their job perfectly. I am sure that they make a 335i sound like an M3 if they wanted to.

Thats a good point. This team probably also consider NVH, cabin insulation and maybee some other things. Would you still think that an engines sound isnt simply an afterthought but an inherent property of the whole engine design. A turbochargerd engine limits the spectrum of the noise available (without artificial intervention) meaning that the sound may be good/bad (thats subjective) just not comparible...its what ive read in a few magazines/books so sorry if im wrong

335i: noticable t/c exhaust note, despite Light boost - this isnt a bad noise!
http://www.youtube.com/watch?v=mDfINoRJeFs

old M3(csl): listen to the shrill it makes near the rev limiter, and how the frequency tells of the engine speed far more noticably
http://www.youtube.com/watch?v=546L60OPhY8

im just exploring this for myself..

[jediali]

pff, that's just massive. lets strap a few turbos on this baby

i say rotary. they are really compact!

keeps matra happy