legacycentral bbs

I know most in here go for the 16g as the normal upgrade route.
I was wondering if anyone has moved to a 18g?

I know I will have to do a serious injector upgrade/ecu mod, FMIC, the big fuel pump.

This spring I plan on working with Kelley on it. Am I going to be the first? My goal is in the 300's at the wheels.

VERY nice!! Kelley will be a good route. It sounds like he has some good stuff for all the things you want to change. If I had more money, I'd definately be considering it as well. His ecu upgrade is very tempting to me.

i plan on going 16g with 18g internals next summer with a modded n/a fuel system. that or a green but it wont be for about a year

Well I'm not really up on all the Mitisu turbos but it sounds good.
Just don't go bigger is better, do the research and get the turbo that will fit your needs.

Good luck

The 18 spools a hair slower than the 16, but has a lot more top end. It is capable of constant 19-20 psi and would work for pushing the 2.2 over the 300 mark. I just have to make sure the ECU, injectors, FMIC and pump can handle the push.

Well the big thing is get a turbo that will get you what you want for power. If you know enough about it and that it will get you what you want it sounds good.
I don't think anyone here is running that big of a turbo. Any plans for the heads. A lot of people talk crap about them but I would like to see how far you can push them.

Good luck with the 300whp

Could the stock tranny handle 300whp?

most likely no

IF I don't do stupid launches, the tranny should do ok. I don't plan on racing it, so it should last for a bit. Long enough for me to find a RA gearset that can handle the power. Or a re-worked tranny.

The 18G won't be the greatest match for our setup.

While we could flow enough fuel for the boost, we don't flow air through the heads fast enough to build sufficient boost. I am at full boost on a 16G with a very well breathing system at around 3300 RPM, and the rev's sweep quick from 3300 to redline. I think you'd probably be at full boost closer to 4000 RPM and by then, you'd have so much lag on the fly, that you'd make 300awhp but only from a launch. You'd take forever to spool up on the highway, and be in gear for to short a time to be in boost for very long before shifting. It would basically be a dyno queen with something that large.

Not to say it's not a cool idea, and hey, I have thought about doing it too. But I would have do go with DOHC and a BUILT valve train to be able to take advantage of the super high flowing turbo. Not to mention your crank case would want to murder you after all of that boost.

I've got an ace up my sleeve for after I get fuel taken care of. Just you guys wait

OK, so what is that ace?
If I go 16G, then I will get nowhere near my goal of around 300+ at the wheels.

Sensei, with what would you suggest this grasshopper do to reach his goal?

ok, i spent a good portion of my day reading up in all the subaru forums on the 18g, 20g, and all the VF series turbos. Since no one has gone my route with the 2.2T, I will worry about head flow if it comes to where that is majorly affecting my overall goal.

I can easily find a set of SOHC or DOHC heads from an early J/E-spec WRX, so If i needed to , I would have parts availability. everyone says the Heads are the worst part of this engine, so I am going to find out at what point that it becomes an issue.

People put 300 to the wheels on the 16G all day long. It's capable of pushing something like 24psi at 7000 RPM. The only problem I see with this, is our head's ability to ingest air. I don't know the specifics of our head flow rates, but I would imagine, that there is significant room for improvement. The problem of "finding out what point it become an issue" is that it is an issue at all points. If the heads flow better, the engine can make more efficient use of the turbo. You want to be able to flow as much air as possible at a given PSI.

Think of it like a garden hose. At a given PSI, unblocked, you get x flow. Reduce the opening at the hose by 50% and the water pressure increases, and the flow rate decreases. This is how it works with heads. The air pressure increases and flow doesn't increase at the same rate. It's like a bottle neck in the intake tract.

Even at 16psi, if the heads flowed better, it would make more power at the same given boost. Backpressure is the devil.

Doing a hybrid head swap, in an application like ours, you want a head that matches fairly well to the coolant passages and such.

Morgie used EJ20TT heads I believe, and had luck with them. If I were to go to DOHC, I'd try and source these heads (do you have a connection to a set of these heads? I would be interested if you did). Then you just need all the internals and such, and put it all together and control it with a standalone ecu. You lose a little low end, but you can make it up in the upper revs with the right setup.

I'll get on the dyno one of these days, and see what I put down. The ole butt dyno, as well as my comparison performance to dyno'd cars, leads me to believe I am putting down between 220 and 250 to the wheels. And that's at 16psi.

hidden cards arent cool. whats the ace?

how much cfm would a head need to flow?

Well, let's do a back-of-the-envelope calculation.

Very roughly 15 pounds of air burn 1 pound of fuel stoichiometrically.

Most Otto-cycle motors burn very roughly half a pound of fuel per horsepower per hour.

So one horsepower is roughly 7.5 pounds of air per hour.

Air weighs about a thirteenth of a pound per cubic foot.

So one horsepower is around a hundred cubic feet per hour, or 1.6 CFM.

Sound right?

I would love to see what people with 16G's are doing on the dyno. If I can go that route, it would be better and cost less.

TT heads (if they work) are not hard to find, because those engines only fit in certain cars (without doing major massaging)

If need be, I can source from Japan and possibly Australia.

It is sad to think that these engines are fairly bulletproof, yet we can't go too far because of the lack of decent heads.

I think in uderstand but just ot be sure to make 300 at the crank you'd have to flow 480 cfm? That sounds huge. Especially considering SOHC EJ25 heads flow 240 cfm, EJ22T heads flow 193 CFM and EJ20 heads flow 151 CFM

Unless I'm completely off my rocker, 99% of the time someone quotes a "CFM number" it's nearly meaningless because of omitted information. People quote CFM numbers all the time, saying "this turbo flows this many CFM" or "this downpipe flows this many CFM" or whatever... The only way to really evaluate a centrifugal compressor, for example, is with a compressor efficiency map, which allows you to correlate efficiency with pressure ratio and flow rate. Those flow numbers were presumably measured on a particular engine at a particular boost level, and the number is only significant for that engine at that boost level.

Similarly, flow benches don't tell you how much flow something can handle. They tell you how much flow it can handle under a certain set of fixed circumstances. Typically this fixed parameter is a pressure differential; you flow enough air through the head to cause a pressure drop of x psi. That airflow then represents how free air is to flow through the head.

But you can certainly force more air through it.

You can flow as much as you want until the air starts to reach the speed of sound. You just get more and more pressure drop as the restriction becomes more and more significant. When we talk about heads, this restriction manifests itself as a loss in volumetric efficiency.

Sorry, that first paragraph was kind of a rant. But it's true. I think.

if these posts wernt so techinal id probaly understand them

What part is unclear? I'll try to explain it in simpler terms...

Go with the stock heads. I sooo want to see how far they can be pushed.

It seems any EJ head will work with our block. 2.5RS guys have swaped in our block on the SOHC and DOHC. CR is the only issue I see.

And come on, out with the Ace.

I have to agree, in that you can force a certain amount of air through the passages and at some point you will get a drop due to the limitations of the valve size or flow characteristics.

the true questions is: WHAT ARE THE TRUE LIMITS?
While I may not be a Chuck Yaeger, I figure, hell, for the extra $200 and a moment on the dyno, we can find out if the 18g pushes the heads to where we see a drop at a certain flow.

Everyone touts these numbers` or those numbers, but if no one has actually tried it, then maybe we should all reserve our judgement until the numbers for this application come in.

If there is an upper limit, I would rather find it than guess.

I'm no fluid dynamicist, but my understanding is that you will always have a pressure drop. The heads are always going to be a restriction at any significant amount of flow. Like I said, the ultimate limit is the choke condition, when air reaches the speed of sound.

I don't think you're going to get near the choke condition. I don't see why an 18G wouldn't work well. You just won't get as much flow at any given boost pressure as you would with better-flowing heads.

-K- wrote:.

It seems any EJ head will work with our block. 2.5RS guys have swaped in our block on the SOHC and DOHC. CR is the only issue I see.

I don't think it's really as simple as that though. I know guys are swapping heads onto our blocks but I know there have been some problems too. Some coolant passages don't match up right, longer headbolts can be needed, and I think Morgie found on the EJ20T heads that one of the headbolts didn't line up right at all. Those are just things I remember off the top of my head but if I'm wrong, I'll be more then happy to admit it. =)