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Old 08-02-2006, 04:55 AM   #1
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Default 10psi???

My current set up is:

greddy turbo, sterion IC, walbro 190 f/p, 1.8 injectors, JB BC, 2.5" cat. back, bipes ACU, new fuel filter, hks SSQBOV, TSI, exedy stage II clutch, JRAFPR

On the Mustang dyno, i hit [email protected] and [email protected] with my current set up. I heard i need to add about 15% if i want to get dynojet #'s.

Currently boosting at 8psi max, and 6psi constant.

I want to hit 12psi max, and 10psi constant.

To get there, i beleive that i will have to change my injectors to 315cc, emanage, and...???

it currently is detonating at full boost. Any recomendations on emanage or ultimate??? i dont need to be flashy so it doesnt matter. i heard that emanage is good enough. but then there are people who tell me that i should get the ultimate.

any other recomendations to get to 12psi peek and 10psi constant?

ps, the boost max out at about 5500rpm. how can i get the boost to redline???
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Old 08-02-2006, 07:31 AM   #2
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What is your fuel pressure at 8 psi boost?
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Old 08-02-2006, 09:02 AM   #3
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Did the dyno measure your A/F ratio as well? Would help to determine how lean you are running when you are detonating or if your fueling is fine it is a timing/heat issue.
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Old 08-03-2006, 04:07 AM   #4
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ok, i will have to measure that when i get back to the states at the end of this month. When it was on the dyno, the air fuel was good. it didnt detonate on the dyno which was weird. timing is set at i beleive 12 or 11 and pull back 6 with bipes. i m not sure because i am not in the states rite now. i will keep everyone posted. i see that there are some people with the same equipment and set up, but they can hit 10-12psi with no problem.
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Old 08-10-2006, 01:25 PM   #5
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will the Emanage get me to 10-12psi??? i will get one of those when i get back to the states. I m really trying to get to 10-12psi with my set up.
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Old 08-10-2006, 01:37 PM   #6
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It should heck i am getting it without so you should get it with.
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Old 08-10-2006, 01:39 PM   #7
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Quote:
Originally Posted by magnamx-5
It should heck i am getting it without so you should get it with.
what psi are u running and how did u get there? what is your set up?
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Old 08-10-2006, 01:43 PM   #8
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According to others that have more experience in the area you should be able to get to 12psi with your current setup and an emanage blue.

I would be concerned that you are having issues with knock at 6-8psi. There is an underlying problem, that will likely not go away on your quest for 12psi.

You might not be getting high enough fuel pressure, or it isn't rising fast enough. Not sure what the JRAFPR is like, I would assume it has some adjustability.

Get the car sorted out with your current setup before adding in more complexity. You should have no issue with with knock at that boost level and the gear you've got. I would hazard to say you could probably get to 8-10psi safely.

How old is your fuel filter? Are the injectors in good shape? How hot was it the day you were on the dyno compared to the days you've been getting knock?

Jay
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Old 08-10-2006, 01:54 PM   #9
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well, it was pretty hot day(80-85f) and we dynoed the car with no detonation. then we went to get food and it did it. the fuel filter is new and the JRAFPR is also new. It can be adjusted so that wont be an issue. the injectors were bought off ebay, and i went through 2 bottles of cheveron w/ techron fuel injector cleaner, so they should be in good shape(the 1.8injectors does seem louder than 1.6) where is my fueling suppose to be? so w/o the emanage, and with my current set up, am i suppose to be at the 8-10psi level? darn, for some strange reason, when i push the car hard, night or day, it will detonate(marbles). can figure that out.
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Old 08-10-2006, 02:24 PM   #10
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I'm sure someone will correct me if I'm wrong.

At 10psi you'd want your fuel pressure to be 110psi. Even if you dead head that high doesn't mean you'll see that pressure, all it means is your pump is probably capable. What you need to do is have a fuel presure gauge installed in the car and then do some runs and carefully watch it. Entering boost it should be 50psi, at 5psi it should be 80, at 8 it should be 98. That's just a VERY loose rule of thumb (50base + 6psi fule for every psi of boost). With the 1.8 injectors you can likely be lower, but you should err on the side of safety.

A lot of people will say that 8psi is the maximum you should push it with out going to another method of management.

If you are getting knock, have you tried to pull more timing with the bipes? Or being more aggressive with it?

Jay
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Old 08-10-2006, 02:44 PM   #11
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To determine the amount of fuel needed in your Miata follow this calculation:
Needed fuel pressure = ( PR^2 x idle pressure) + boost

Pressure Ratio (PR) = 14.7 + boost / 14.7

Example:
6psi = 1.408
1.408^2 = 1.98
Idle pressure = 36
(1.98 x 36) + 6 = 77.38psi

At 6psi you want to be able to supply 87psi of fuel (10psi more than needed to be safe).

To determine the amount of fuel you can supply with your AFPR or FMU follow this calculation:

Fuel pressue @ rail = Rise x boost + idle pressue
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Old 08-10-2006, 03:06 PM   #12
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what is a good fuel guage to pick up? i want to make sure that i have the "correct/accurate" fuel pressure. will the 1.8 injectors be good enough to supply 10-12psi? i couldnt find too much info or write ups on the emanage. thanks all for the helpful info!
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Old 08-10-2006, 03:30 PM   #13
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Bruce (olderguy) is still running 1.8 injectors and seeing +12psi of boost. Since the Emanage allows you to adjust the length the injectors stay open and so on you can supply sufficient fuel. Otherwise a 230cc injectors is going to be maxed at around 160-170rwhp depending on boost, fuel pressures and so on.
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Old 08-11-2006, 12:04 AM   #14
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wow this is great info! i cant wait to go back to the states and tinker with her! anyone running 12psi know what the hp and 1/4mile time? just estimate.....
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Old 08-11-2006, 12:56 AM   #15
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i am running some 310's and a rx7 maf with WI i will turn up the boost abit soon. now i am runningat 10 psi hope to get atleast 12 i have a 12-1 rrfpr and a walboro hp 190. As i said i still need to dyno but it feels stronger than the 200 dynojet whp at 8-9 psi i got on my previus dyno runs. BTW i also dont run any timming control either it works for me. Andy Floyd runs the peiburg rx7maf and some 330's and turns 12.2 sec 1/4 mile times on his setup at 16 psi or so i forget the exact boost number but it is up there. for injector info go here and play around for a while.
http://www.rceng.com/technical.htm#WORKSHEET
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Old 08-11-2006, 12:57 AM   #16
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i have had it up to 20 psi but it wasnt making power no fuel so i have no doubt my WI is working becouse i wasnt knocking either.
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Old 08-11-2006, 03:29 AM   #17
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what does WI stand for again?
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Old 08-11-2006, 09:36 AM   #18
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Water Injection, instead of using an intercooler.
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Old 08-11-2006, 09:48 AM   #19
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Quote:
Originally Posted by zbossrt
wow this is great info! i cant wait to go back to the states and tinker with her! anyone running 12psi know what the hp and 1/4mile time? just estimate.....
How about more numbers to crunch:

Using these numbers as a guideline, you can select the approximate injector size in the following formula for your Miata to reach an estimated 240HP (est. 195rwhp):

Est. Horsepower x B.S.F.C(.55) / # of injectors x duty cycle(80%) = lb/hr per injector

cc = lb/hr x 10.5

240 x .55 / 4 x .8 = 132 / 3.2 = 41.25 lb/hr x 10.5 = 433cc

Then determine the amount of fuel pressure you will have @ the rail to determine what injector will reach this desired cc level:

PSI / 43.5 = NF

Square Root of NF x est. injector size = cc level

At 12psi with a 8:1 ratio FMU we will have 132psi of fuel @ the rail. We will need to find an injector that will flow 433cc at 132psi.

132 / 43.5 = 1.931

sqrt of 1.931 = 1.74

1.74 x 250cc = 435cc

So with a fuel rail pressure at 132psi 250cc injectors with flow enough to provide you with enough fuel for 12psi and 195rwhp. These numbers aren't exact but it's a close estimate, your idle pressure will change the outcome of these results, I used 36psi.

Or if you dont feel like doing math, or I completely lost you....plug in the numbers here: http://www.rceng.com/technical.htm (use .55 for BSFC, .8 for duty cycle, and use your est. fuel rail pressure)


The problem at this point is your running a lot of fuel pressure in the rail. Now Corky Bell thinks this is perfectly safe (kinda), but if you lines, injectors, rail or fpr ever fail you're not going to be having a good day. With an E-Manage you can lower your fuel rail pressure but still adaquately fuel for 12psi using smaller injectors.

Last edited by Braineack; 08-11-2006 at 10:18 AM.
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Old 08-11-2006, 10:04 AM   #20
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I've found that .55 seems to be a more accurate number for the BSFC figure for our cars, in general.
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