Max boost on stock injectors....

Dr. Gonzo · Post by **Dr. Gonzo** » Wed Aug 27, 2008 10:25 pm

I've done a little searching and haven't found my exact application addressed so here's my Q:
I have a TD04, 06' TMIC, 3" exhaust, 45 degree intake & 255lph pump and I'd like to know at what boost level I'll max out the stock injectors (no, I have no way of measuring duty cycle, just looking for a best guess). Using equations found on here I can guess what the stock injectors will max out at in terms of HP, but I don't know what that exactly translates into as far as what psi I set my car at? Oh yeah, I'm at 5000 Ft ASL and currently set at 11psi with no sign detonation. I have a FCD that I won't put on utnill I know I'm safe above 12 psi or I get EM, which ever comes first. (I have bigger injectors but i found out they're 480cc not 440cc's so I need to save up for EM in order to run them which may be a couple months.)
Thanks in advance

Arctic Assassian · Post by **Arctic Assassian** » Thu Aug 28, 2008 2:08 am

about 15 psi

dzx · Post by **dzx** » Fri Aug 29, 2008 6:26 pm

I run about 18psi but i think the gauge shows less than what a dyno pressure guage would show. Never heard the engine ping or seen signs of detonation.

farfrumwork · Post by **farfrumwork** » Tue Sep 02, 2008 10:38 pm

Hey fellow CO subie-dude,

What I do is look for where the injectors go static. Basically at some air flow (which is related to boost) the MAF goes to 5.0v which in turn makes the injectors go static.

I stripped some wire to fit into the MAF connector (some diagrams somewhere here that shows which wire is which) and then metered that with a multimeter (tapped to the windshield - classy!) I found that on a cool day (~45F) I was hitting 4.8v at around 13psi. I leave it at that level usually as to have some headroom.

I know many EJ22T owners run boost levels that must throw the injectors into static and get away with it, but 100% duty cycle isn't good for your motor, injectors, emissions, and most importantly not good for POWA

It's obvious with these motors that much massaging at all leads to bigger injectors, bigger (or deleted) MAF, and EM real fast. That's where I am now.... I can't add anymore boost (due to air metering and therefore injectors) and I have no way to control timing, which is key for making good power.

Short answer - (here at altitude) somewhere around 13-14psi (in 4th) if you want to be in the range that the system can control.

Dr. Gonzo · Post by **Dr. Gonzo** » Wed Sep 03, 2008 4:51 am

Thanks for the first hand high altitude advice, farmfrumwork

. Your approach is logical and sounds pretty realistic. I'm going to set it around 13-14 and save for EM...
Do you have a similar setup?
Going back to bandimere any time soon?

dzx · Post by **dzx** » Wed Sep 03, 2008 8:42 pm

I run the jecs maf and haven't seen the injectors go static yet. With the hitachi maf though they would go static and the engine wouldn't make much power. I recently starting mixing e85 with 91 octane and like how it feels.

farfrumwork · Post by **farfrumwork** » Thu Sep 04, 2008 11:17 pm

We have sort of similar setups.

My '93:
VF12 (closer to a 16G size-wise)
Custom A/W intercooler
3" CES TBE (catted)
MBC
LW underdriven Pulley

I'll be back to Bandi to run next year when I have something new to test... probably some P&P headers with high flow cross-pipe early spring (and maybe EM by the end of the 2009 season)

I'm down there this Sun (9/7) for the import drags - just a spectator though

dzx · Post by **dzx** » Mon Sep 08, 2008 11:11 pm

Let me know when you go, I should run my legacy at the track sometime.

Dr. Gonzo · Post by **Dr. Gonzo** » Tue Sep 09, 2008 5:50 am

Yeah, I'd be game as well.

farfrumwork- see any legacy's?

Dr. Gonzo · Post by **Dr. Gonzo** » Wed Sep 10, 2008 5:07 am

Thread hi-Jack FYI- I'm going to bandimere on the 26th, see you there...

farfrumwork · Post by **farfrumwork** » Thu Sep 11, 2008 5:53 pm

nope no old school Legacy's at the "tuner mayhem" - but a Outback XT with roof mnt bike racks was running 101mph - sweet.

I liked seeing ALL the cars that are slower than mine though

. The biggest class was 15.0 and slower (emphasis on "slower") - I could take every single car in the class

- I felt smug sitting in the crowd. Of course there were many cars that would totally destroy mine - but that's always the case.

I can't go the 26th - that's my son's birthday! But I look forward to hearing what you put down Gonzo. Launch hard!! I go from 5500 or so for consistent 2.0 60's (a few high 1.9's too)

BXSS · Post by **BXSS** » Thu Sep 11, 2008 7:13 pm

It seems that the 15.0 & slower class is always won by a 19-20 second auto @ my local track while the 12-14.99 class is always mixed in terms of winners.

I plan on dragging the SS alot next year (once I get a v-body & t-converter for my 4eat from IPT) & my target time for bracket racing will be 14.99's in the 12.0-14.99 class - I hope to get a few class winner stickers with this car.
I'm pretty sure the SS should be able to run 14.99's with about 10psi of boost on the 16G/El headers these days.

Dr. Gonzo · Post by **Dr. Gonzo** » Thu Sep 11, 2008 7:20 pm

Hmmm, so should I enter the 15+ class? I hope to break into the 14's but I've only road raced, never drag raced so I'm not to confident in my launching/ starting skills. Is it best to short shift, around 5500 or so? Thats where it feels like the power is falling off.
Thanks!

BXSS · Post by **BXSS** » Thu Sep 11, 2008 8:44 pm

Yeah shift @ around 5500 & you should be OK!

dzx · Post by **dzx** » Fri Sep 12, 2008 7:57 pm

so what happens if you enter the 15+ class and run under?

Dr. Gonzo · Post by **Dr. Gonzo** » Sat Sep 13, 2008 1:03 am

I believe your DQ'd, not sure if you can run again in a faster class??
dzx- Is your leg by chance white? I saw a white one with a front mount at the king soopers in Gun barrel the other day.

Matt Monson · Post by **Matt Monson** » Sat Sep 13, 2008 1:27 am

farfrumwork wrote:nope no old school Legacy's at the "tuner mayhem" - but a Outback XT with roof mnt bike racks was running 101mph - sweet.

You mean this one? You should see under the hood. He's running a rotated mount turbo and E85 on that thing. It makes power in the high 300's at the wheels!

That was taken at the CSP track on Table Mountain last month. Many of the Colorado Suby contingent will be there again on the 27th. Flatirons Tuning along with the financial assistance of SOA is running an all Subaru open track day. It's $50 a head, which is about $100 cheaper than a usual track day. There will be several OG Leggies there including Siouxbe and Etchylives. You guys should come out.

/shameless plug

Matt Monson · Post by **Matt Monson** » Sat Sep 13, 2008 1:28 am

Gonzo,
I see no mention of a FCD mentioned anywhere in this thread. You are currently about 1-1.5psi from hitting fuel cut. If you want to go any higher you will need to either make one or buy one.

dzx · Post by **dzx** » Sat Sep 13, 2008 6:25 am

Yeah it's white, I'm a pharmacy tech there. I need to replace the front window.

Dr. Gonzo · Post by **Dr. Gonzo** » Sat Sep 13, 2008 7:05 am

Matt Monson wrote:Gonzo,
I see no mention of a FCD mentioned anywhere in this thread. You are currently about 1-1.5psi from hitting fuel cut. If you want to go any higher you will need to either make one or buy one.

It's in my original post. I have one but haven't put it on yet, was waiting to see what was safe.

dzx-cool, I work right off of 75th on winchester circle.

tmarcel · Post by **tmarcel** » Fri Sep 19, 2008 2:40 am

Max boost is a little generic as it really comes down to airflow. Anyway, you only have a couple or so options with the factory ECU. Since you aren't able to easily log duty cycle (you could probably rig up a multimeter though) you would otherwise need to look for AFR feedback through a 5v wideband. You would also need to be able to see fuel pressure.

It would go something like; 1.) If the AFR leans out but fuel pressure stays constant then the injectors are likely wide open. Or, 2.) if the AFR leans out and the fuel pressure drops then the pump is likely not able to keep up. Sounds crude but that's fairly basic for tuning a motor.

farfrumwork · Post by **farfrumwork** » Thu Sep 25, 2008 11:25 pm

Matt - yup that was him. super cool.
27th is out for me though.

And weird on the Gunbarrel connection - I work out here too. The big Covidien campus on Longbow Dr. We design and produce electro-surgical products. (previously known as Valleylab)

And on shifting - I run 1st to redline (it's over so fast anyway), and 2nd around 6250, and 3rd 6-6250.

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Max boost on stock injectors....

Max boost on stock injectors....