EJ22 boosted?

[Phizinza]

Would like to know about boost and EJ22's. As in, how much can they take, reliably and the most people have got out of them? Is it the ECU that is the issue stopping it from having more boost, or mechanical strength?

[Legacy777]

Are you talking about non-turbo EJ22's? I'm going to assume you are.

 

The big thing is going to be the compression ratio. With the stock compression ratio of 9.5 to 1, you won't be able to run a lot of boost. Most people that I've heard of boosting non-turbo subie engines only run between 5-7 psi of boost. You will also need some form of engine management, piggy back to control things

 

The other thing to note is the pistons are going to be stronger on the turbo motors to help deal with the added temperature and load from the turbo.

[Phizinza]

Yes, non-turbo EJ22.

 

We would be running it purely on LPG with a distributor, no electric management.

 

So would you get more power with less compression and more boost, and how would that work surely less compression means less air thus negating the extra boost?

[NorthWet]

Less base compression means lower thermal efficiency when not super-atmospheric (<1bar).

 

*Edit - OK, it lowers TE throughout, but it will be noticeable when you are off-boost.

Edited November 15, 2010 by NorthWet

[Phizinza]

Ok, I've read some text about turbocharging. I understand the figures and how to work it out, but still don't understand why dropping the pressure and then replacing it with boost makes such a big difference but I trust it works.

So here are my latest thoughts. EJ20t block, EJ18 heads, EJ Disty from NZ, LPG, Supercharger from V6 engine. This is all for a mate, he already has the supercharger and wants to use it for something a little different. Due the conditions we'll be using the car in I've decided LPG is the best fuel for the job. And simpler the better! I know LPG isn't popular in the US, but in Aus it is used on plenty of cars and can be had at every servo.

[idosubaru]

from memory reddevil (username) did some great work supercharging his NA EJ engine. i'd check out his stuff, should be relevant to you.

[Scoobywagon]

Just because I'm curious, and I'm certainly not criticizing, but why are you getting away from the electronic engine management?

[Legacy777]

The main reason you see a decrease in base compression ratio when going to turbo or super charged engines is due to normal gasoline's inability to ward off pre-ignition or autoignition at higher temperatures caused by higher CR's.

 

If you run race gas with a higher octane rating, then you could get away with a higher base compression ratio and run more boost.

 

Since you're planning to run LPG, I'm not sure how that fuel will compare to gasoline. I'd suggest doing some research on what the comparable gasoline anti-knock index or grade would be for LPG. If it is comparable or higher to what your "premium" fuel would be, you can probably get away with a little more boost. If it's lower, you will likely run into issues.

 

 

Edit: Did a quick search and I haven't found any hard numbers, but it's looking like propane has a high anti-knock index. It's not as high as natural gas, but still pretty good compared to gasoline. With that being said, you could likely run the stock CR and more boost without autoignition. This is a document from the DOE's website. It has info on CNG and automobile engines....it may be helpful.

 

http://www.osti.gov/bridge/purl.cover.jsp;jsessionid=42C46D14FA0C3A2886ED35D0E8C0DB2C?purl=/2469-QJvGAp/webviewable/

Edited November 15, 2010 by Legacy777

[GeneralDisorder]

If you wanted to do it you could just use an EJ22T ECU, add the boost control solenoids and MAP sensor, turbo MAF, as well as the turbo injectors (pink top) etc. Then you just drop the boost a little lower than what the ECU runs it at. I've heard of them handling 5 or 6 psi for many years and although that doesn't sound like a lot - at 9.5:1 compression ratio it IS a lot. Supposedly about 200 HP or so with a ton of low-end torque due to the high compression ratio.

 

GD

[Rooster2]

Less base compression means lower thermal efficiency when not super-atmospheric (<1bar).

 

*Edit - OK, it lowers TE throughout, but it will be noticeable when you are off-boost.

 

Less base compression would also mean slower acceleration for about the first three to five seconds from a dead stop, when adding a turbo as described. Then as boost spools up, the extra power could be felt.

[Ross]

Since you are running LPG, you should be fine with the higher compression ratio. Depending on the exact mix, it will have an RON of 105 or higher.

 

You wont get good results using a distributor straight from an EJ. At the very least you'd need to change the weights and provide some kind of boost retard system. Much easier and better, IMO, to go with a megasquirt or something and run the standard wasted spark system. Then the only thing you need to do to get a nice tune is some reading, rather than mucking around with distributors.

[Phizinza]

Thanks guys.

I've been reading more on boost and compression ratio. I understand it now and how it works. Same pressure more volume.

Yeah, I've heard LPG is like a 110oct rating. So it should love boost. The reason we want to go with no engine management is to simplify. After a race weekend having trouble with the weber carb loosing power over bumps and seeing all these $100k+ racing 4WD's having fuel issues I thought just keep it simple! And with running LPG, no need for a computer so may as well not have it. But I see what you are saying about the distributor. Hmm, will need to think about it!

 

As far as I know, we don't have EJ22t's in Australia. All the turbo Liberty's we got here had EJ20's. I've been thinking using an import STI block (forged internals) and SOHC heads (to fit into the Brumby). Along with some other parts...

Edited November 16, 2010 by Phizinza

[Ross]

I know what you mean about simplicity, but don't rule out a simple engine management system like the megasquirt. Since you build the system yourself, you know exactly what is doing what, and you can make it as simple or as complicated as you like.

 

I use a megasquirt ecu and a ford falcon throttle body injection unit on my suzuki samurai and have never looked back... although it does take a bit of tuning to start with. Much more reliable than the stock carb that was on there....

[subaru360]

Would like to know about boost and EJ22's. As in, how much can they take, reliably and the most people have got out of them? Is it the ECU that is the issue stopping it from having more boost, or mechanical strength?

 

The EJ22E engine itself will hold up fine. I've run 20+ psi of boost on them and 300 whp. No breakage. I wouldn't push it much harder than that though. After my success a few other guys on nasioc copied me and have run the same setup. EJ22E shortblock with EJ205 heads.

 

You can't run a stock N/A ecu. You will blow it up. The key to making it work is either a factory turbo ecu, standalone or piggyback and a proper fuel system including pump and injectors.

[Xanadu62]

EJ205? is that a typo? I could understand a set of 25 heads. Kinda like putting a set of chevy 305 heads on a 350 block, but in reverse. I have the postal 2.2 in mine, and from what ricearu has told me, it is a bit of a bastard motor. It is a gen 2 non-interference motor. It only has about 112k on it. Do you think that it would be ok to boost it? Anyways, with the right internals, you can boost anything as much as you want. There's diesel pulling competitions where the motors are boosting 135-150psi! I actually agree with the higher comp boost idea though. Subies are kinda fat and need the low end torque to get everything going.

[subaru360]

No EJ205 heads. You need wrx intake manifold, wiring and ecu. It's a nice combination.

 

The postal legacy has the same 2.2 as any other legacy or impreza.

[Ross]

Anyways, with the right internals, you can boost anything as much as you want. There's diesel pulling competitions where the motors are boosting 135-150psi!

 

False. With a petrol engine, internals are really the least of your worries. The limiting factor is controlling pre-ignition. The higher your compression ratio, and the higher your boost pressure (which effectively increases your compression ratio, that's the point) the more trouble you will have preventing the fuel/air mixture from igniting itself before the spark.

 

Because diesel engines only inject the fuel when combustion is wanted, they do not suffer this problem, and can run as much boost as you want to throw at them (within reason....). In fact, throwing more boost at a diesel engine, while keeping fuelling constant, cools down the exhaust gas temperatures -- the main limiting factor on power output of a diesel.

 

Hrm, a bit off topic, but oh well.