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Hi-power, tricked EJ... some advice?


MoscowSubaruDude
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I am asking around for a friend of mine, can't say too much, but the engine I'd like to build would be going in a rather large custom mechanized type piece of fun. Think some really weird biped stuff. High-power is a must, and well as low-end torque. Somewhere in the 400-ish HP range. So I was thinking perhaps an EJ25T, fitted with a supercharger instead of a turbo for the low-end torque... perhaps a mild hit of nitrous. Reliability is a must, it doesn't sound like this will be an easily removable engine, so it needs to be semi-durable, as in going at least 2-3 months without any kind of overhaul. Budget is not firm yet, so what I'm looking for is some figures, using two basic sets of criteria:

 

1) low-budget, used engine, junkyard parts, etc etc. belt driven supercharger.

2) hi-priced, brandnew cosworth parts, etc etc.

 

Options for fuel delivery, like MegaSquirt, or whatever... just looking for the basics, and rough dollar figure per engine. Thanks all.

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There is an expression, "You get what you pay for." So, if you are looking for reliability, then don't look for a junk yard engine. Also, just because you buy great parts, if they are not assembled correctly, they might as well be junk yard parts. Cosworth parts are spendy, but if I were to build an all out performance engine, their parts would be a starting point. Before you think about using a supercharger instead of a turbo, do your homework. If this is going to be a biped (aka motorcycle), the torque generated by a turbo engine should be plenty. I'll take you for a ride in my stock JDM powered 96 WRX and you can see how much torque only 260hp (last dyno) will give you, believe me, it's plenty.

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At the very very least... 500 shp, and roughly the same amount of torque. It's a direct-drive machine, so the motor(s) will be driving the machinery via a system of clutches, shafts, and various linkages. I may have to run two engines in this beast, but hey, I can fit 2 suby motors in the space and weight of 1 caddy big-block, which is their proposed engine.

 

To give ya'll a good idea, I've included this link, the company website:

 

www.mechaps.com

 

It's a rather interesting project, and the reason I'm asking all these questions is because I'm going to try and get on the Jan 07 intern cycle as a mechanic, responsible for the engine. Several people in the company are intrigued by the capabilities of the Suby motor. So.... anyone who has any ideas to crank out more power, do tell. I can build anything, so it's not much of a problem, as far as assembly is concerned. Also... I'm debating whether to used the EJ25 4cyl, or the 3.0 6cyl from the outback... and I seem to remember Subaru making a 3.3 liter 6 as well, which would be awesome... so once again, lets hear it.

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400-500 hp plus reliability?

 

Stick with the 472 Caddy Engine!!!!!!!

 

seriously.

 

I see alot of those 400-500 whp Subarus, I also see them broken. To get 400-500 whp you need 25 plus pounds of boost. First, supercharger will never ever boost that much. Second, you sound like you need something that goes and goes. Ever seen the glow of a 500 hp turbo? It lites ************ on fire!

 

I love my supercharger, but I know its limitations. About 300 whp.......

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Ok then... good to know that it's not feasible. I do know that there are suby engines being built to crank out lots of ponies, just don't know if they're entirely reliable. Thanks!

Reliability and performance are inversely related: More power = less reliable. Once you get much beyond 100HP/liter (1HP/CI) reliability starts going south without expensive metallurgy.

 

The route to HP is RPM, not boost.

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...Once you get much beyond 100HP/liter (1HP/CI) ...

Okay, before somebody points out that my two values aren't equivanlent, they were meant to express the last-Millenium view of high-performance: 100HP/liter for foreign OHC engines and 1HP/CI for Detroit pushrod V8s.

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Ya know... i was thinkin about something today... (dangerous, i know) but the STi comes stock with 300 hp, right? In what, a 3-liter? 2.5? that's 100 hp per liter. Now, there are people having a lotta fun with these motors, and how much are they getting? 400? 500? horses? 500 horses... now how much reliability? anyone have a daily driver that comes even remotely close to those numbers? If i can produce that much, I'll be happy. Just a thought...

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  • 2 weeks later...

Ok, so I have seen something subaru based that might get you into this range, with some serious work. Twin turbo'd SVX motor. It displaces 3.3 Litres, and stock NA pulls around 260 hp. It comes with forged pistons, however they are too high compression to be suitable.

 

A preliminary idea of what you will need to do:

 

Exhaust manifold

Perhaps cut, reverse, and reweld the intake manifold

A suitably large intercooler

A much beefyer transmission

A new bottom end if you are really serious

Serious headwork

 

I have seen one example, and it never got finished. And I cannot find the pics. But exist it does.

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