Faelflora breaks his promise to break no more parts. He breaks eddy brakes. - Page 172 - Miata Turbo Forum -Boost cars, acquire cats.

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Old 08-16-2012, 07:34 AM   #3421
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Originally Posted by Leafy View Post
Well saying sucks ***** is a bit harsh, more like mildly annoying. Though I constantly humble myself by looking at the 90's haltech we have that you have to tune with dos, and shudder.
No, it DOES suck *****.
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Old 08-16-2012, 07:39 AM   #3422
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Yes, that's me. FM's dyno is pretty accurate, I believe, but the debate lies in whether the SAE correction should be applied to a turbo car to account for the mile-high altitude (my take is that there should be some correction, but not that much). My uncorrected chart from those runs were about 325 whp, which jibes with a local Dynojet run here at 2,000 feet.

Both the FM and local dyno sessions were less than optimal. At FM, we were chasing a fueling issue (ultimately caused by a failing fuel pump) and ignition woes (originally attributed to dwell settings but ultimately fixed by changing out to NGK race plugs). Here at home, I was running with sub-optimal fuel numbers, finally traced to an incorrectly-calibrated WB sensor. In other words, there's more in my system than I can prove with existing dyno charts. Given that, Fae should be making far better numbers than he has (so far). Summary: The Hydra is not the problem.
Ah ok...

I put down 245whp on FM's dyno, and this is probably the slowest 245whp car i've ever driven in my life. Feels more like 150whp at best.

I don't think that Hydra is the problem here, even though i HATE my Hydra, and it seems that FM couldn't even get my car running correctly. (Driveability is downright awful.) The issue here is clearly the dyno. The dyno was so messed up that you can't even accurately say that FaeFae's car is making 350whp.

Judging from videos (because, you know... this is accurate) i'd say he's well into the 400whp range, likely over 450whp.
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Old 08-16-2012, 09:08 AM   #3423
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Originally Posted by Faeflora View Post
OK. Why
because I understand "the 1000 cc injector squirted for X.XX milliseconds" better than I understand "the 1000 cc injector squirted for 70% of the time at whatever RPM I am at"

Also, you said DC was off.
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Old 08-16-2012, 09:19 AM   #3424
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Originally Posted by Faeflora View Post

Maybe i dun busted my regulator
What does it show at idle?
What does it show at idle when you pop off the vac line?
Do your IPW increase when you lean out now vs before when it didn't? Or are they the same.

Talked to my buddy with the crapped out regulator yesterday, and his diaphram started leaking inside the regulator when this started happening.
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Old 08-16-2012, 02:38 PM   #3425
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Originally Posted by 18psi View Post
What does it show at idle?
What does it show at idle when you pop off the vac line?
Do your IPW increase when you lean out now vs before when it didn't? Or are they the same.

Talked to my buddy with the crapped out regulator yesterday, and his diaphram started leaking inside the regulator when this started happening.
Idle is like 70-75psi.

When I pop off vac line I forget what it is at.

IPW did NOT increase when I leaned out. Stay the same.

BTW. I just popped off my fuel rail lines. Both fuel pumps are flowing just fine. Massive, massive, amounts of fuel all over my garage floor.
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Old 08-16-2012, 02:41 PM   #3426
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Oh THAT'S how you test your pumps??!?!

Mind = BLOWN
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Old 08-16-2012, 02:41 PM   #3427
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idle at like 70-75, so your base pressure is like 85ish? which is the pressure that you get when you pull the vac line off the fuel pressure regulator, of if you just jumper the fuel pump on when the car is off.
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Old 08-16-2012, 02:44 PM   #3428
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Whoa... what? No check valve in line to keep engine vacuum from dropping your fuel pressure?
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Old 08-16-2012, 02:46 PM   #3429
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I hope not. you want engine vacuum to drop your fuel pressure. Especially with (fancy) high flow injectors.
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Old 08-16-2012, 02:48 PM   #3430
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Originally Posted by TurboTim View Post
I hope not. you want engine vacuum to drop your fuel pressure. Especially with (fancy) high flow injectors.
I guess the injectors are probably the difference. On one of my other Mazdas i had to run a one-way check valve to keep the vacuum from killing the motor, and that was with 45psi base fuel pressure. (higher than stock.)

Ooorrrrrrrr... maybe i just learned an important lesson?
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Old 08-16-2012, 02:49 PM   #3431
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Originally Posted by TurboTim View Post
I hope not. you want engine vacuum to drop your fuel pressure. Especially with (fancy) high flow injectors.
Yup. You want your fpr to reference manifold pressure any and all manifold pressure. Its so hard to tune an engine in right when the pressure doesnt vary 1:1 in vac never mind boost. You want to keep the same differential pressure across the injectors no matter the conditions in the manifold.
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Old 08-16-2012, 02:54 PM   #3432
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Originally Posted by Leafy View Post
Yup. You want your fpr to reference manifold pressure any and all manifold pressure. Its so hard to tune an engine in right when the pressure doesnt vary 1:1 in vac never mind boost. You want to keep the same differential pressure across the injectors no matter the conditions in the manifold.
I have to run a base pressure of about 65psi just to keep it running smooth at idle without the check valve. That gives me fuel pressure of 85psi+ under full boost 1:1, and that's a bit out of my comfort range when working with a Walbro 255 and stock supra 440 injectors. (And running pretty rich, at that.)

45psi base w/ check valve hitting around 65psi at full boost yielded good AFRs and an idle that worked.
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Old 08-16-2012, 02:55 PM   #3433
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Quote:
Originally Posted by concealer404 View Post
I guess the injectors are probably the difference. On one of my other Mazdas i had to run a one-way check valve to keep the vacuum from killing the motor, and that was with 45psi base fuel pressure. (higher than stock.)

Ooorrrrrrrr... maybe i just learned an important lesson?
Yeah, like leafy said. 1:1 regulators are the norm, the pressure differential is always the same across the injector. Makes life easier.

And your check valve would hold boost inside the regulator signal... i.e. once you reach your xx psi, that's what the regulator would stay at until it leaks down which, depending on the check valve quality and volume inside the regulator/line, might take a while.
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Old 08-16-2012, 02:57 PM   #3434
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Add more fuel with your tune? I dont know what to tell you. I have run into tuning stock cars that dont have a vac reference fpr and they have a 1d table that modifies the injector pulse width based on vac so that you can get VE tables that make sense.
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Old 08-16-2012, 03:06 PM   #3435
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Originally Posted by Faeflora View Post
Idle is like 70-75psi.

When I pop off vac line I forget what it is at.

IPW did NOT increase when I leaned out. Stay the same.

BTW. I just popped off my fuel rail lines. Both fuel pumps are flowing just fine. Massive, massive, amounts of fuel all over my garage floor.
If your idle fuel pressure is 70PSI, this explains your leaning problems. Your poor fuel pump is crapping out.

1. Disconnect vacuum line to pressure regulator.
2. Set pressure to 45PSI.
3. Connect vacuum line back.
4. Re-tune the fuel map as it will be too lean
5. Give us a good dyno run on a good dyno!

Remember typically regulators are 1:1. So if your idle is 70psi, your open air is 80ish which means with 35psi of boost you will be at 115PSI. Most pumps will have a hard time getting that high or if they do, the volume flow drops dramatically. You have no reason to run 70psi fuel pressure at idle.
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Old 08-16-2012, 03:11 PM   #3436
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He has not 1 but 2 MAMMOTH pumps. Way way way more than he needs. I don't think they're tapped out, but who knows.
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Old 08-16-2012, 03:14 PM   #3437
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Fuel flow typically tapers off exponentially as pressure increases. It would not be surprising if those pumps did not flow nearly enough fuel at 115 psi, but could easily flow enough at 90psi.
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Old 08-16-2012, 03:19 PM   #3438
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Quote:
Originally Posted by TurboTim View Post
Yeah, like leafy said. 1:1 regulators are the norm, the pressure differential is always the same across the injector. Makes life easier.

And your check valve would hold boost inside the regulator signal... i.e. once you reach your xx psi, that's what the regulator would stay at until it leaks down which, depending on the check valve quality and volume inside the regulator/line, might take a while.
Ah ****... i didn't think about that. :(

It is a 1:1 regulator, though. Aeromotive 13109.


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Originally Posted by Leafy View Post
Add more fuel with your tune? I dont know what to tell you. I have run into tuning stock cars that dont have a vac reference fpr and they have a 1d table that modifies the injector pulse width based on vac so that you can get VE tables that make sense.
This is a VAF car with no real tuning provisions at the moment other than a boost controller and AFPR.

I have research to do i see, on the subject of figuring out how to make the car not run at like 8:1 under full boost with 85psi of fuel pressure.

/threadjack
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Old 08-16-2012, 03:39 PM   #3439
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I don't think your problem is fuel flow. Even though you're apparently running the pump beyond what is usually considered advisable or sensible, a single 044 should provide enough flow for the current setup at 35psi. Two of them are super-massive overkill.
I was not able to quickly find published data for flow of the 044 above 100psi, but at 100psi it still flows a massive 390lbs/hr. And the characteristic curve is still almost flat/horizontal in that area. So at 115psi we should still see considerably more than 300lbs/hr.
Fuel Pump Comparison

Still: Lower your fuel-pressure, re-tune and see what's happening!

Leafy: What do you mean "Fuel flow typically tapers off exponentially as pressure increases"? Characteristic curves of fuel pumps are usually pretty well approximated by two or three straight lines. Looks more like something logarithmic to me, if any. Please elaborate what an exponential taper-off is.
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Old 08-16-2012, 03:48 PM   #3440
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Originally Posted by stefanst View Post
Leafy: What do you mean "Fuel flow typically tapers off exponentially as pressure increases"? Characteristic curves of fuel pumps are usually pretty well approximated by two or three straight lines. Looks more like something logarithmic to me, if any. Please elaborate what an exponential taper-off is.
I meant at the trailing end. The couple I've seen where they run the pump pressure all the way up till the pump stops flowing there is a certain point where flow just nose dives. I keep forgetting that the 044 is such a high pressure capable pump that he wasnt likely close to that number. For example, look at that denso pump on that link it starts to drop like a rock.
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