Engine Design
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tjamz wrote:
all are good designs really...I'm sure the domestic guys will say V8, most of the import guys will say I4/I6, and us Subie guys will all say boxer.....most will probably agree w/ me about overhead>pushrod.
when all is said and done, sell the motor to me.
Pushrod, 16 vlave V8 > all...
As for selection, it depends on what you are going for. As for sheer power, V8 engine have the advantage of having more CI. Any engine can be made to flow more, or have N20, or FI strapped too it, but it is much harder to come by those extra cubic inches. -
uhh.. the choice is obvious. You have to build a hemi.
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Forced induction. Design a new rotory that will last 250,000 miles.
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I vote for a forced induction rotary that will run on ethanol. Rotaries have one of if not the best power to weight ratio for engine designs. If you want more torque/hp just add more rotors :). Turbocharged and burnin' moonshine, sounds delicious.
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^yea...make it a four rotor monster
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tjamz wrote:
all are good designs really...I'm sure the domestic guys will say V8, most of the import guys will say I4/I6, and us Subie guys will all say boxer.....most will probably agree w/ me about overhead>pushrod. If you want to build a pretty bad ass motor relatively cheap, get a block from a 90-94 Subaru Legacy Turbo (ej22t is the engine code.) Build the motor to rev to 8,500, stroke it to 2.4 or 2.5 liters and put a T67 on it. 8.5:1 compression, JUN valvetrain & cams on a WRX head that has been P&P'ed. Make sure you port the TB and remove the tumble generator valves, modify the stock injectors (cut the screens off, they will flow ~740cc).when all is said and done, sell the motor to me.
do what he said!
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adog wrote:
What type of application is the engine going to be used with? Of emissions, economy, performance, and durability, which is most important?
I would probably say that performance and durability. The application could be my stang if the engine works out right, but for now its just for display for a huge project for graduation. -
how about a 2L 90deg banked V8, and make it rpm screamer.
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4L straight 8? 90mm bore x 80mm stroke? should produce some mean tq and rev to the sky.
10:1 compression and keep it n/a; aluminum block with iron sleeves (don't screw up and use aluminum like honda did with the b20a5 and the b21)
if you're planning on potentially using this engine, i don't know how large it would be, but i can see it having some real potential. or... you could take the ideas that others have suggested and produce a rotary that will run on alcohol... except that would likely need at least 3 rotary chambers to make enough power considering the lack of energy in alcohol -
Forced Induction Inline 6 all the way.
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So the priorities are performance, then durability, with fuel economy being a secondary concern? I would go with a cast-iron sleeved aluminum block in either an inline-6 or V8 (maybe inline 8 if it could fit). For a car engine, a DOHC 4V/ cylinder setup would be nice, with variable valve timing a plus. Make it continously variable for bonus points. If you really wanted to get crazy, you could design an electrically operated head. If you actually wanted to build it, I would just use a late model Cobra head or a ported 2JZ (I don't know a whole lot of other options for an inline-6). Either way, get as much displacement as you can in your engine bay. (The DOHC V8 will be limited here.) I would keep it over-square (more bore than stroke), but that's just me. Try to keep the piston as short as you can, but remember that shorter pistons require tighter tolerances. For actual use, forged 4340 rods would be nice. Otherwise, or if you're infinitely rich, titanium. Incorporating a girdle into the design would be a big plus with the V8. Keep compression in about the 9-9.5 range. Multi-port fuel injection and a good tune would be good. Then, depending on your preference, use either a twin-screw blower or turbo with moderate boost, intercooled. Bam! All the power you could ever really use, in a fairly street-friendly package and still probably emissions legal and decent on the gas, depending on the cam and exhaust.
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Just copy the designs of the Toyota 2JZ GTE. I may be a Nissan guy, but I won't hesitate to admit that the 2JZ is arguably the best motor designed in the 90s.
I don't know of any other engine that can make over 1000hp on a stock block.
-Peter
1991 240SX
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