Hybrid motor (high compresion)

[STIll inspired]

i recently finally got my first car. i knew for a while the only car i wanted was a subaru and wouldn't you i got it!! woohoo. i picked myself up a 2000 lgt high mileage body with a bunch of mods already preformed on the car.the cars original motor had died so the motoer was replaced by a 2.5rs phase II motor but it didn't stop there. the previous owner was big on performance and i don't blame him. he then procceeded to build a hybrid using phase II 2.2 heads and an sti head gasket. but that isn't the end of it he then added a stage 1 crank 04 2.5rs injectors a cold air intake and a few other bits. as of now the car is a blast and has been checked out by a former head tech at subaru and he himself was impressed on the drive and response from the vehicle and it's power delivery. now after reading up on a few threads i have realised there maybe a few issues that could occur with these types of setups. my question to anyone who can help what should i beware of and what can i do to prevent any major issues.
thanks
-Uriah

[StatGSR]

Keep up with regular maintenance.

what issues are you referring to?

[STIll inspired]

i was referring to possibly having the bottom end go out. piston issues or spun bearings. according to other sources i may need forged pistons to handle the compression but that would mean i would have to rebuild the bottom end too.

[jey]

Any modifications to the engine management? As long as that is set up well you should be ok. There are people even doing forced induction on the NA block.

[Huffer]

Treat it right and it'll treat you right. You'll have to be extra wary on important items like temperature, oil pressure etc so if you don't have them yet, get some monitoring gauges.

[STIll inspired]

Any modifications to the engine management? As long as that is set up well you should be ok. There are people even doing forced induction on the NA block.


there has been no modification to the engine management system.

[STIll inspired]

Treat it right and it'll treat you right. You'll have to be extra wary on important items like temperature, oil pressure etc so if you don't have them yet, get some monitoring gauges.



good call... now where can i get the gauges and instrutions on putting everything in?

[Grafton]

As long as you don't knock you should be fine, what octane are you running?

[anothernord]

Run the highest octane you can get your hands on.

To get the most of a good motor like this, you'd ideally want some sort of engine mangment.

[Grafton]

Run the highest octane you can get your hands on.

To get the most of a good motor like this, you'd ideally want some sort of engine mangment.

I agree 100%

[Reason]

Another one, nice

[STIll inspired]

As long as you don't knock you should be fine, what octane are you running?

no knocking at all. knock on wood. i try to run 93 but if not i run 91 or if that's not available idk what i would use i guess 89.

[STIll inspired]

Run the highest octane you can get your hands on.

To get the most of a good motor like this, you'd ideally want some sort of engine mangment.


well i have heard some rediculous prices for engine manage ment and maybe that could be in my future but being 16 i don't believe that i could and should invest in something so expensive at least as of now i thought about doing delta cams as i have seen many people have had success using those but once again that will have to wait for a while yet. hopefully the cash flow will grow soon!!!!!!! :grin:

[anothernord]

Emanage Ultimate can be found for ~$400.

[STIll inspired]

Emanage Ultimate can be found for ~$400.


how well will it preform and does it have a fully optional tuning set up to suit my needs?

[anothernord]

Emanage Ultimate can be found for ~$400.


how well will it preform and does it have a fully optional tuning set up to suit my needs?

Well, its a tuning system, so you have to tune it yourself, or have someone tune it. But it has lots of capability; mainly adding the ability to advance timing, and control fuel. Those two things are really what makes more power in an engine.

[STIll inspired]

Well, its a tuning system, so you have to tune it yourself, or have someone tune it. But it has lots of capability; mainly adding the ability to advance timing, and control fuel. Those two things are really what makes more power in an engine.[/quote]


okay so what kind of power gains could i expect by adding cams, forged pistons, and a complete bottom end rebuild?

[Grafton]

only power adder is the cams, bottom end and pistons are relibity enhancers

I'm not bothering with the bottom end, the people before me haven't, it seems to be up to the task

[STIll inspired]

only power adder is the cams, bottom end and pistons are relibity enhancers

I'm not bothering with the bottom end, the people before me haven't, it seems to be up to the task


i understand the "hp" is added by cams but won't the light weight pistons allow for more torque or at least a quicker response?

[Grafton]

i understand the "hp" is added by cams but won't the light weight pistons allow for more torque or at least a quicker response?

It's not enough weight to make a measurable difference, however a lightweight flywheel make a huge difference.

[impreza_GC8]

Lightweight flywheels are not very good mods for daily driven subarus. Our AWD systems like to have some weight behind them. If you are still N/A, EMS might not be hugely important, I'd be curious to know what your CR actually is, there are ways to compute it that are beyond me but not difficult for someone mathematically minded. Honestly I wouldn't put any more money into that motor build unless it is to turbocharge it.

[grayguy]

Does anyone have any dyno numbers for this setup? My GF wants more power in her 2.5RS...

[rougeben83]

I would seriously try to calculate what CR you are running right now. Unless the heads have been shaved, I don't think the CR is that much higher than stock. Mind you STI headgaskets are slightly thicker than stock, this actually lowers your CR a little.

Also, I don't know what's part of a "stage 1" RS crank...has it been blueprinted? Knife-edged? Who did the modification? None of these, as stated before, actually increase HP, they just allow the crank to work/be lubricated better at higher rpms, thus increasing power. If you don't have a higher redline than stock, you're not going to see any added HP.

Also, AFAIK, 04 rs injectors aren't all that much higher rated than any other n/a subaru. They're going to be around 250-300cc max. For reference, the stock 2.0l wrx injectors flow 340cc stock, and this is for a high-boost application.

I'm sounding like a downer, but what I'm trying to say is find out more about your setup and the particular specs of it; then you can have a better idea about what to address to optimize for power. I've said it time and time again but throwing random parts at a car and hoping it will work for the best is not the most efficient or cost-effective way to make power.

[STIll inspired]

I would seriously try to calculate what CR you are running right now. Unless the heads have been shaved, I don't think the CR is that much higher than stock. Mind you STI headgaskets are slightly thicker than stock, this actually lowers your CR a little.

Also, I don't know what's part of a "stage 1" RS crank...has it been blueprinted? Knife-edged? Who did the modification? None of these, as stated before, actually increase HP, they just allow the crank to work/be lubricated better at higher rpms, thus increasing power. If you don't have a higher redline than stock, you're not going to see any added HP.

Also, AFAIK, 04 rs injectors aren't all that much higher rated than any other n/a subaru. They're going to be around 250-300cc max. For reference, the stock 2.0l wrx injectors flow 340cc stock, and this is for a high-boost application.

I'm sounding like a downer, but what I'm trying to say is find out more about your setup and the particular specs of it; then you can have a better idea about what to address to optimize for power. I've said it time and time again but throwing random parts at a car and hoping it will work for the best is not the most efficient or cost-effective way to make power.



in all honesty i have no details on the crank.
the injectors weren't ment to overload the engine and make it run rich but to allow more flow to compensate for the heads and crank. (i'm assuming)
i will definately try to get ahold of the previous owner and get more details but from personal experience and from a former subaru tech the ride is pretty incredible. there is a noticible power gain from the modification so i will look into figuring out all of the nitty gritty details.

[jey]

Lightweight flywheels are not very good mods for daily driven subarus. Our AWD systems like to have some weight behind them.

Actually I daily drove my Subarus and found the lightweight flywheel to be one of the best mods ever. Still don't understand why Subaru has to use such a heavy flywheel - takes forever to rev-match.

[rougeben83]

Ditto, lightweight flywheel really brought the car to life when I put it on.

[Airgne]

^agreed. i hvae light weight flywheel, aluminium pressure plate, and crank pully. those are some of the best mods i did.

haveing those with cams if you get them, you will run into miss fire codes alot. i get them when im really pushing it.