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 Post subject: 2 stroke 1 liter v4. ..
PostPosted: Thu Oct 21, 2010 8:39 pm 
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ok its not very realistic but http://www.aaenperformance.com/V4_racing_engine.asp


Aaen V-4 Two Stroke Racing Engine

Weight Width Length Height

95 Lbs. 18" 16" 14"

44 kg. 457 mm 406 mm 355 mm


Aaen V-4 Two Stroke Racing Engine

Engine Config. Bore & Stroke Displacement HP @ RPM

V-4 Drag 65 X 58.5 800cc 215 @ 10,000
V-4 Drag 74 X 58.5 1025cc 275 @ 10,000
V-4 Road Racing 67.5 X 58.5 850cc 200 @ 9250


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V4_engine.jpg
V4_engine.jpg [ 13.46 KiB | Viewed 3792 times ]

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PostPosted: Thu Oct 21, 2010 9:13 pm 
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This might hold back some low cost builders.

"We will only sell these engines to qualified Race Teams with solid budgets large enough to support extensive development necessary for top level racing, for more information on the V-4 Engine, please refer to the SAE papers #983071 and #983080 presented at the 1998 Motorsports Conference in Detroit. "

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PostPosted: Thu Oct 21, 2010 9:25 pm 
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Sounds like they want customers to fund their research. Must be nice.

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PostPosted: Fri Oct 22, 2010 3:16 am 
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Even besides what Kurt said, I can't be the only one skeptical of the longevity and reliability of engines advertised for racing.

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PostPosted: Fri Oct 22, 2010 10:45 am 
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Even besides what Kurt said, I can't be the only one skeptical of the longevity and reliability of engines advertised for racing.


Well they're made from good stuff. I think the 10 hour service life for a road racing engine is largely a reflection of running it's parts very close to the limit for failure.

If you drop the redline about %20, that would get you a big increase in life. If you can detune a bit with a milder cam to reduce valvetrain loads now you would get many more miles. Maybe not 250k, but you would get 100 times the life probably. The life decreases very rapidly at the limit.

It would be harder to detune these two strokes though, but if you could move the ports down a bit that would be a big help. I think they do have some legitimate concern not to sell their product to folks who have no idea how to feed and maintain very high power two strokes. They just aren't casual endeavors.

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PostPosted: Fri Oct 22, 2010 10:49 am 
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No cams in a 2 stroke.

Notice the decrease in rpm and hp on the road race version.

That would sure sound gnarly tho!

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PostPosted: Fri Oct 22, 2010 10:54 am 
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No cams in a 2 stroke.


Not this one. But I was talking in general. For those that really want a DFV :)

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PostPosted: Fri Oct 22, 2010 1:47 pm 
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What's special about high power two strokes? I've never dealt with them, and have no idea about their potential.

I can see how putting the
Quote:
We will only sell these engines to qualified Race Teams with solid budgets large enough to support extensive development necessary for top level racing, for more information on the V-4 Engine, please refer to the SAE papers #983071 and #983080 presented at the 1998 Motorsports Conference in Detroit.
disclaimer would really reduce the amount of inquiries with no hope of a sale.

It would be a really interesting engine IF:
1. Detuned, it still put out comparable power to a hayabusa or r1 car kit
2. Lasted as long as those bike engines in cars(I've read bike engines are only good for 10-15k miles in cars, before needing a rebuild. Any truth to that?)
3. Was priced competitively compared to a hayabusa+dry sump(if dry sump is included)+reverse box(since I'm assuming you'll mate this to a car transmission with reverse). But even then, r1+baffled sump is so much cheaper.
4. Easily available, reasonably priced bellhousings to a common, locost friendly car transmission.

The fact their contact email on their website bounces doesn't exactly encourage anybody however.

Here is a 165 lb, similarly sized 200hp motor.
http://www.weber-motor.com/en/products/ ... index.html
http://www.weber-motor.com/fileadmin/te ... /V4_NA.pdf
But again, I'm clueless as to the expected longevity of powersport motors, and how that would translate into a car. Though they state automotive use, there are no car pictures.

I have a feeling all these 'oooh, wouldn't that be nice' engines are impractically expensive. :ack:

I can't be the only one interested in a 160-200hp, 100-150lb engine that'll bolt to a car transmission though. :lol:

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PostPosted: Fri Oct 22, 2010 4:17 pm 
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What's special about high power two strokes? I've never dealt with them, and have no idea about their potential.


Very few moving parts, small size, high power are the basic things. Compare a flat plate for a cylinder head to a 4-stroke with valves, springs, guides, tappets and cams for example.

With a 4 stroke If you want to change the basic tune you have to send your cams out for re-grinds. The equivalent on a 2 stroke is to redesign the shape of the expansion chamber exhaust or grind the ports on the piston with a die grinder.

If you run it lean though problems get bad quickly because the oil is mixed with the gas, so lean mixture also involves oiling failure. The mixture goes thru the crankcase, so even the crank will have oiling troubles.

Their basic power advantage is they fire twice as often.

This is all somewhat simplified and there are exceptions, but that's the overview. If you wanted to build your own motor from scratch a 2 stroke is basically doable.

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PostPosted: Fri Oct 22, 2010 4:20 pm 
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horizenjob wrote:
Quote:
... If you wanted to build your own motor from scratch a 2 stroke is basically doable.


Especially if you do direct cylinder fuel injection.

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PostPosted: Fri Oct 22, 2010 5:43 pm 
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Especially if you do direct cylinder fuel injection.


So you can use a conventional oiling system? It might be sensible, but you need an oil pump and drive, galleys to distribute the oil in the block and crank. The motorcycle 2 strokes I've worked on are scary simple, and there is something to say for that. They use cranks with ball and roller bearings that are built up with press fits. They don't even have rod bolts.

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PostPosted: Sat Oct 23, 2010 4:06 pm 
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I'm noticing a few things written about two stroke engines here that aren't exactly accurate. A lot of them use an oil injection system for lubrication so there is no oil mixed with the fuel. Even with the oil injection, it is very important not to run lean as that will melt pistons and seize an engine very fast. There are also two stroke engines with camshafts, look at an old detroit diesel for an example. They used transfer ports for the intake and a camshaft to control exhaust valves in the head and the injectors.

You can make good power from a small two stroke engine and have it last for quite a while too, if it is properly tuned, but they are very sensitive to altitude changes making them run rich or lean. (I don't have experience with EFI two strokes, so I am refering to carbureted engines.) The reason they have to be carefully tuned is that even a little bit rich will knock the power down big time. The engine in my snowmobile is an old Rotax 670cc twin that makes around 140 hp. It will run reliably at 8700 rpm making max power all day long as long as it is tuned correctly and this engine has probably around 15,000kms on it without being rebuilt. Running at max power it might get 5 mpg, which is a major downfall for two stroke engines. The old 500cc grand prix race bikes were around 200 - 250 hp.

Kristian

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PostPosted: Sun Oct 24, 2010 6:30 am 
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turbo_bird wrote:
I'm noticing a few things written about two stroke engines here that aren't exactly accurate. A lot of them use an oil injection system for lubrication so there is no oil mixed with the fuel. Even with the oil injection, it is very important not to run lean as that will melt pistons and seize an engine very fast. There are also two stroke engines with camshafts, look at an old detroit diesel for an example. They used transfer ports for the intake and a camshaft to control exhaust valves in the head and the injectors.

You can make good power from a small two stroke engine and have it last for quite a while too, if it is properly tuned, but they are very sensitive to altitude changes making them run rich or lean. (I don't have experience with EFI two strokes, so I am refering to carbureted engines.) The reason they have to be carefully tuned is that even a little bit rich will knock the power down big time. The engine in my snowmobile is an old Rotax 670cc twin that makes around 140 hp. It will run reliably at 8700 rpm making max power all day long as long as it is tuned correctly and this engine has probably around 15,000kms on it without being rebuilt. Running at max power it might get 5 mpg, which is a major downfall for two stroke engines. The old 500cc grand prix race bikes were around 200 - 250 hp.

Kristian


only direct injection will make automotive 2 strokes viable in the long term. all major engine manufacturers have direct injected 2 strokes on the pipeline.

i wonder if race engine designers would consider direct injected 2 strokes if allowed by the rules. i think a loop scavenged design will be capable of even higher rpms than ever. and double the power to weight ratio of 4 strokes with similar displacement.

all giant sized diesels are mostly 2 stroke.


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PostPosted: Sun Oct 24, 2010 2:34 pm 
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flat4 wrote:
turbo_bird wrote:
I'm noticing a few things written about two stroke engines here that aren't exactly accurate. A lot of them use an oil injection system for lubrication so there is no oil mixed with the fuel. There are also two stroke engines with camshafts, look at an old detroit diesel for an example. They used transfer ports for the intake and a camshaft to control exhaust valves in the head and the injectors.
The old 500cc grand prix race bikes were around 200 - 250 hp.

Kristian


only direct injection will make automotive 2 strokes viable in the long term. all major engine manufacturers have direct injected 2 strokes on the pipeline.

i wonder if race engine designers would consider direct injected 2 strokes if allowed by the rules. i think a loop scavenged design will be capable of even higher rpms than ever. and double the power to weight ratio of 4 strokes with similar displacement.

all giant sized diesels are mostly 2 stroke.


Wow a lot of misinformation in this thread.

Oil injection does mix with the fuel, it just saves the owner pre-mixing it by hand. I can't recall a production petrol 2 stroke that doesn't need oil to pass the combustion chamber although I know prototypes with isolated primary compression cycles that don't.

Jimmys (Detroit Diesels) don't have transfer ports, a supercharger positively displaces air direct into the combustion chamber straight through the cylinder wall ports.

500cc GP bikes never passed 200hp on track but I heard a few dyno runs saw just over in perfect test cube conditions.

Some manufacturers have tested 2 strokes mostly modded by The Orbital Engine Company with direct injection but they will never see production. A friend of mine who is a top Ford Engineer handled 3 test cars for Ford Australia driving them around.

Loop scavenged designs? What do you mean? Loop scavenge has been around since the mid 60's since the advent of pressure wave supercharging (expansion chambers). Literally every one of the millions of common 2 strokes has been a loop scavenge since then and up till this very day.

It has been well proven that as the displacement goes up the power advantage of a 2 stroke falls eventually behind a 4 stroke, around a 300cc cylinder is about where they equalize but then the 4 stroke will carry a smaller weight of fuel and be packaged easier due to the lack of expansion chamber. After 300cc, eventually the 2 stroke can't touch the 4 stroke. However the small stuff rocks, an 80cc common kids MX bike puts out more hp per litre than an F1 race car.

Just a couple of other common myths about 2 strokes, they actually make huge torque compared to a 4 stroke and they don't rev hard for comparable power, they just sound like they do. For comparison an older Honda CR250 2 stroke MX bike made 50hp at 7000rpm and a current Honda 250 4 stroke MX makes 35hp at 13,000rpm. For further comparo, a 125MX 2 stroke made 40 hp at 10,000rpm or less.


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PostPosted: Sun Oct 24, 2010 7:54 pm 
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i wasnt referring to current 2 stroke designs using port injection or carburators ans crankcase scavenging. these needs oil mixed in the gasoline or sprayed in the crankcase to lubricate the main bearings. that is one of the root of all 2 stroke problems.

when i said loop scavenged i did not mean crossflow crankcase scavenged; i meant schnuerle ported and blower/supercharge/turbo scavenged. sorry for being vague.

loop scavenged designs are very simple but not as efficient as uniflow or reverse uniflow designs. but they can go really fast.

direct injection solves almost all problems inherent in 2 strokes. like what has been said elsewhere its a totally new ball game for 2 stroke petrols.

2 stroke diesels has been very successful in the very big size applications precisely because it uses direct injection. its a natural for diesels. of course there is also the question of scale but direct injection scales down very well.


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