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PostPosted: Fri Feb 25, 2011 2:03 am 
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I know bmw put 4 cyl turboed engines in their formula one cars along time ago and were making around 1200hp from 2 liters ..but these things were like hand grinades ,they dont even bother measuring boost in psi ,its bar at that point.I know that guys have got well over 1000 hp from almost stock rb26dett 's that came in japanese skylines but to get that sort of power was twisting the blocks and cracking them,they then built grank girdles that helped,look its my understanding that building the engine properly is half the equation ,the other being fuel and ignition management,there are a few companys out there that build computers to run these engines but they alone cost thousands,to get what you want id say you had better empty your piggy bank of around 25 grand.


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PostPosted: Fri Feb 25, 2011 11:35 am 
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The BMW F1 engine once went as high as 5.5 (80psi, estimated 1300HP) and didn't get far past the end of the pitlane but did make it the most powerful race engine ever to see a race track even if for 100 meters. The F1 teams ran around 4.0 bar reliably eventually at around 900HP more for qualifying. Renault ran cast iron blocks for big boost qualifying and aluminium for race.

Theres some crazy comments in this thread.


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PostPosted: Fri Feb 25, 2011 3:04 pm 
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flat4 wrote:
mild steel is 2 times stronger than cast iron and 10 times the fatigue life.


Stop right here. Go to homemodelenginemachinist.com and lurk their forums, then build a small ICE from scratch, only after you have done this can you even think about making major engine parts from scratch. Mild steel may be stronger than cast iron but if it's Cold Rolled then it's stressed and you can't do anything with it. You need stress relieved Mild steel which you can't afford (of your own admission). There is a reason that engineers design engines in aluminum and cast iron, and if it was just for cost effectiveness then they wouldn't appear in race engines (which they do).


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PostPosted: Fri Feb 25, 2011 3:08 pm 
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Cheapracer said:
Quote:
Theres some crazy comments in this thread.


And while that is the truth, is it really all that different from the other ones in here??? :lol:

:cheers:

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PostPosted: Fri Feb 25, 2011 3:35 pm 
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13B with a turbo. .. if you want really light use the aluminum end castings available, you end up at ~110 lbs for the assembled block.

Are you perhaps asking about maximum cylinder pressure rather than manifold pressure? A turbo and engine is just an air pump feeding an air pump, manifold pressure is a ratio of what they can each process at a given moment in time.
Cylinder pressure on the other hand is what beats on the rods and crank throws as well as the tops of the pistons.
Theres a lot to consider, you can offset piston pins to increase torque directionality, rod ratio, crank throw and material, rod material, just to name a few. Will a block flex? Sure but only as much as you fail to convert the vertical piston movement to a circular crankshaft rotation. Its all about the math, so define the variables first.

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PostPosted: Sat Feb 26, 2011 3:47 am 
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GonzoRacer wrote:
Cheapracer said:
Quote:
Theres some crazy comments in this thread.


And while that is the truth, is it really all that different from the other ones in here??? :lol:

:cheers:


I laffed! :lol:

Note to Mods: This forum seriously needs a better LOL and Thumbs Up smiley!


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PostPosted: Sat Feb 26, 2011 6:14 am 
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flat4 wrote:
ok i found out that highly turbocharged engines can reach 3000 psi. thats all i need.


Wut.


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PostPosted: Sat Feb 26, 2011 10:09 am 
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milo wrote:
flat4 wrote:
mild steel is 2 times stronger than cast iron and 10 times the fatigue life.


Stop right here. Go to homemodelenginemachinist.com and lurk their forums, then build a small ICE from scratch, only after you have done this can you even think about making major engine parts from scratch. Mild steel may be stronger than cast iron but if it's Cold Rolled then it's stressed and you can't do anything with it. You need stress relieved Mild steel which you can't afford (of your own admission). There is a reason that engineers design engines in aluminum and cast iron, and if it was just for cost effectiveness then they wouldn't appear in race engines (which they do).


thanks for the link! its very interesting.

hot rolled mild steel is good enough. race engines dont use steel because welded crankcases are not allowed by the rules. whats the point of using cast steel? really thin castings is very hard to do. better to cast aluminum in thick sections. if welding was allowed they would all be using friction stir welded aluminum cases.

i can cast an aluminum crankcase if needed. but then whats the point? id rather use a subaru.

the tvr cerbera speed 12 used a welded steel crankcase and it worked. but as tvr noted its not amenable to high volume production. but with the current welding technology, low volume production is feasible. with cnc machines economy of scale dont mean anything any more.


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PostPosted: Sat Feb 26, 2011 10:18 am 
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JSullivan wrote:
Wait.

Let me get this straight.

You aren't an engineer, you aren't willing to pay an engineer.

But you want to build your own turbo engine from scratch that is under 95kg and can be a stressed member that can last 1000 hours?


im a retired software engineer. i wrote engineering software for 10 years. i can do the math given the time and data.

well a type 1 vw can produce 40 hp continuously for a long long time. i am trying to build on that. im not trying to outdo the f1 guys.

have you seen a pauter super pro case? costs an arm and a leg and yet people buy those!


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PostPosted: Sat Feb 26, 2011 10:26 am 
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oldejack wrote:
13B with a turbo. .. if you want really light use the aluminum end castings available, you end up at ~110 lbs for the assembled block.

Are you perhaps asking about maximum cylinder pressure rather than manifold pressure? A turbo and engine is just an air pump feeding an air pump, manifold pressure is a ratio of what they can each process at a given moment in time.
Cylinder pressure on the other hand is what beats on the rods and crank throws as well as the tops of the pistons.
Theres a lot to consider, you can offset piston pins to increase torque directionality, rod ratio, crank throw and material, rod material, just to name a few. Will a block flex? Sure but only as much as you fail to convert the vertical piston movement to a circular crankshaft rotation. Its all about the math, so define the variables first.


sorry to be ambiguous. i meant peak cylinder pressure.


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PostPosted: Sat Feb 26, 2011 10:30 am 
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cheapracer wrote:
The BMW F1 engine once went as high as 5.5 (80psi, estimated 1300HP) and didn't get far past the end of the pitlane but did make it the most powerful race engine ever to see a race track even if for 100 meters. The F1 teams ran around 4.0 bar reliably eventually at around 900HP more for qualifying. Renault ran cast iron blocks for big boost qualifying and aluminium for race.

Theres some crazy comments in this thread.


im not trying to outdo the f1 guys.

i just want an engine that can do high boost continuously. the main constraint is the weight. a 1930 design can do 40 hp continuous. surely using the lastest science on it can make do more.


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PostPosted: Sat Feb 26, 2011 10:38 am 
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wayne-o wrote:
I know bmw put 4 cyl turboed engines in their formula one cars along time ago and were making around 1200hp from 2 liters ..but these things were like hand grinades ,they dont even bother measuring boost in psi ,its bar at that point.I know that guys have got well over 1000 hp from almost stock rb26dett 's that came in japanese skylines but to get that sort of power was twisting the blocks and cracking them,they then built grank girdles that helped,look its my understanding that building the engine properly is half the equation ,the other being fuel and ignition management,there are a few companys out there that build computers to run these engines but they alone cost thousands,to get what you want id say you had better empty your piggy bank of around 25 grand.


i need continuous boost. not a 30 second 1000 hp burst. if it is 150 hp or 200 hp doesnt matter. i just need that 95 kg lump to put out as much as it can.

if im going to spend that much anyway i think its better to spend them on interesting stuff!


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PostPosted: Sat Feb 26, 2011 10:45 am 
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Laminar wrote:
flat4 wrote:
ok i found out that highly turbocharged engines can reach 3000 psi. thats all i need.


Wut.


i meant peak cylinder pressure. that is very high i know. only 60 plus psi boost can generate those. im only looking at 14 psi boost.


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PostPosted: Sat Feb 26, 2011 10:50 am 
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oldejack wrote:
13B with a turbo. .. if you want really light use the aluminum end castings available, you end up at ~110 lbs for the assembled block.



nice but i need it to take chassis loads.

but then whats the duty cycle for peak power? 75% power?


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PostPosted: Sat Feb 26, 2011 11:21 am 
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To be honest I don't know what the rated power is on one of those in an airplane application but using a rotary is a fairly common means of powering sport aircraft. They do use a beam bolted to the front of the engine as a motor mount in stock applications.
Another possibility given your current "blank slate" stage is something along the lines of a "gnome" engine.
A lot of advantages given that airplanes need torque more than acceleration and you could have the prop blades bolt directly to a cylinder wall exterior. Air cooling becomes a given since the cylinders are out in the airflow which reduces weight and since those engines use the bulkhead as an intergral part of the engine I'd say it would definitely be a stressed member.http://www.animatedengines.com/gnome.shtml

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For instance, a whole beer bottle isn't half the weapon that half a beer bottle is ..." Randall Garrett


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