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DIY Turbo Discussion greddy on a 1.8? homebrew kit?

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Old 08-17-2007, 11:31 AM   #21
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Quote:
Originally Posted by greddymx5 View Post
you need 6 psi fp / psi off boost.
I keep seeing that "fact" thrown around here. The required rise in fuel pressure is totally dependent on fuel supply/demand, i.e. injectors and power (which is not totally dependent on boost).

Maybe I misunderstood your post in the holistic sense, but 6psi fuel pressure rise per pound of boost is not a be all and end all truth. In fact, it isn't even a decent guideline. Some quick math is a much better, much safer way to figure it out.
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Old 08-17-2007, 03:02 PM   #22
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If you're seeing an increasing lean condition during Boost, then you don't have enough fuel. What disc ratio in the Vortech are you running? What injectors are you running (stock?). If you're running a 12:1 disc in the Vortech, even on an EVO8 pump (which I suspect is stronger than a stock Miata), and stock injectors.... YOU PROBABLY DON'T HAVE ENOUGH FUEL! You need a fuel pressure gauge that you can see while driving to get a pressure reading so you can do the math and see if you've got enough fuel.
Stock injectors are good to over 130psi of fuel pressure (maybe more, Corky says injector lock is almost impossible on the inj's we run).

I'm surprised nobody has mentioned a fuel filter. You need to change it.

If you'll look back to my first post, you'll see I asked about YOUR CLUTCH!!! If you are spiking to 15psi, I GUARANTEE YOUR CLUTCH IS SLIPPING!!! Do you know what a slipping clutch feels like? Boost+RPM increase+no power= possible slipping clutch! Even the 8psi you think you're running is more than enough to smoke the stock clutch.

I also see that your valve cover breather tube is just open to the air. You need to route it properly... at least put a filter on it or something.
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Old 08-17-2007, 03:55 PM   #23
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Quote:
Originally Posted by Atlanta93LE View Post
I keep seeing that "fact" thrown around here. The required rise in fuel pressure is totally dependent on fuel supply/demand, i.e. injectors and power (which is not totally dependent on boost).
So many people speak as if psi is an absolute. "How many psi before my head gasket blows? How many psi can I run with X? How many psi can the stock engine handle? What size fuel injector do I need for 10psi?" 10psi on a Greddy is not the same as 10psi on a T25 is not the same as 10psi on a GT35R is not the same as...and etc.

Anyway, just wanted to rant a bit.

In my experience, if the car has boost and isn't "moving", as in it's making a **** ton of noise but the RPMs won't climb, it's a lean issue.
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Old 08-17-2007, 04:17 PM   #24
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Quote:
Originally Posted by Atlanta93LE View Post
I keep seeing that "fact" thrown around here. The required rise in fuel pressure is totally dependent on fuel supply/demand, i.e. injectors and power (which is not totally dependent on boost).

Maybe I misunderstood your post in the holistic sense, but 6psi fuel pressure rise per pound of boost is not a be all and end all truth. In fact, it isn't even a decent guideline. Some quick math is a much better, much safer way to figure it out.
I totally understand that with a diff turbo the fuel requiements will change, just want to point out where his problem might be... Not a guideline for tuning all turbo's...

Setting a car up just with a vortech req a lot of calculation.12:1 to much for everything above 6psi or a larger fuelpump.

Get a calibration set and a walbro and check in out...
It's a nice,cheap option to let the car run rich in boost.
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Old 08-17-2007, 09:32 PM   #25
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This is just a whole accident waiting to happen. For one, you need to have some measure of boost (gauge). Second, you really need to retard timing if you do not have a controller. I have a MSD box for sale for like 75 shipped if you want it. Third, jesus measure some fuel. I am willing to bet your exceeding your present fuel system. You have too many variables which ultimately lead to engine failure. Fix them fast before you decide to keep driving it.
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Old 08-17-2007, 09:40 PM   #26
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You have no boost gauge and no timing controller? Have fun blowing up your motor.
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Old 08-17-2007, 10:07 PM   #27
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damn i missed that go buy a frigin boostgauge damn.
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Old 08-18-2007, 02:21 AM   #28
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i mentioned that i had a faulty boost gauge...and that has already been replaced...and i have dialed in the wastegate arm...im now running 5lbs of boost which should by me some time so i can throw the money down to get some type of fuel management!!!!...the car is running great but i have yet to adjust the cas...where is the bolt that im looking for?...as far as the clutch, it was replaced with a spec stage 3 6puck sprunged clutch...basically the first thing i replaced when i bought the car!!!(3months old)...I believe a company rre(big time 4g63 guys) pressure tested the evo8 fuel pump and with good results the pump flowed close to a 190 both at 12v and 14v(is it possible to increase voltage?) http://www.roadraceengineering.com/f...pflowrates.htm the vortec fmu is a 12:1 and afrs are fluctuating between 12:8-13:1 in the upper rpms(keep in mind this is now 5lbs and with the evo 8 pump installed)...
--the car no longer bogs because i wasnt able to see how much boost i was running...so all i really need to do is tune the base timing to get rid of knock!!!
--thanks guys!!! the pics of the setup was the first day i installed my pieced up turbo kit!!!

Last edited by o.e.boost; 08-18-2007 at 02:41 AM.
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Old 08-18-2007, 02:37 AM   #29
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a little off topic but the evo guys can help with the flow of the stock fuel pumps...and the evo 8 pump is a lot bigger than that of a stock miata pump!!!...i just might be upgrading to a evo 9 pump since its able to flow more...
heres the link
http://forums.evolutionm.net/showthr...fuel+pump+test
--in my opinion this is an option to those who a) dont really want to hear the noise of a walbro and B) knows a buddy or use to own an evo and has a boat load of stock parts!!!...freebies as i call it!!!
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Old 08-18-2007, 05:01 AM   #30
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It's not flow, it's pressure. To run an FPR, you need a fuel pump that will support 100+psi. If a stock Evo8/9 pump will do it, great; at stock pressures, the stock Miata fuel pump will flow 350+rwhp.

Just get a PNP MS and stop dicking around with all this bandaid ****.
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Old 08-18-2007, 07:03 AM   #31
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I would also run your oil feed line to your turbo so it isn't cable tied to your heater hoses and near your wiring harness. Stainless braid hoses are like a saw blade with all the vibration in a car and will chew through almost anything!
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Old 08-18-2007, 10:28 AM   #32
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Rerence there chart bud at 90+ psi of FP the evo pump flows enough fuel for 0 hp the evo 9 pump can hit 150 hp at 90 psi but the walboro 255 hp supports 300+ hp at 90+ psi fuel pressures. A 190 hp can support up to 340 hp at 90+ psi. The evo pumps flow a little more than a 190 standard pressure. With out the headroom for pressure increase. This is why you are running a FPR increase the FP to make the injectors act like big injectors. Do you understand what we are screaming now, a walboro 190 hp or 255 hp is only 90-100 bucks shipped. How much does a evo pump cost?
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Old 08-19-2007, 04:59 AM   #33
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20 bucks or free on the cost of an evo 8/9 fuel pump!!!...but i do see your point and have come across your point by other fellow miatat.net guys like brain...to sum it up...squeezing a load of fuel through small injectors to act as if you were running x size injectors. But to rely on a fpr/fmu can be fatal if the disc seizes up and wouldn't the idc be off the charts?...im not sure about the accuracy of a tune with a fmu but wouldnt running high pressures decrease the life of the fuel system as well?(pump, injectors,...etc)...i will be dropping the fmu in favor of bigger injectors/rail just because of the reliabilty of another asset added to the miata's fuel system...but i feel that the fmu is an option for me for now, since im on a budget...
--back on the topic, ampz thanks for looking out as i oversaw the oil feed line and the hose/harness...i didn't have much time cleaning up a quick/rushed install...the engine bay still remains dirty but i hope to clean all that dust!!!
--savington...to answer all your questions...i had a faulty boost gauge meaning the gauge was off by alot, which is replaced!!!...besides the stock wastegate on the saab should be @ 8psi wastegate pressure so i expected too much from a virgin wastegate...and to answer your question about dicking around with the bandaid ****...i will be getting pnp ms as an engine management but the funds are not just there...making power and restoring the car is a good sum of money since i didnt buy a car in such a good exterior and interior shape...i just found out i bought a 94 r model miata...besides guys have made respectable power with the very items like a afpr/fmu and are still using them in their current setup...
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