Single Turbo RX-7's Questions about all aspects of single turbo setups.

Enough Fuel pump & injectors?

Old 03-01-15, 05:43 PM
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Enough Fuel pump & injectors?

Hey guys, im trying to sort out my fuel system for my single turbo setup.

I have read both of Howards threads re Fuel Pump sizing & fuel injector sizing, but just want to make sure I understand this before I order anything (else)..Im done with hasty decisions and buying things twice..

Turbo is a BW S360. I plan on running around 400 RWHP but I understand one should spec the fuel system off the max air the turbo can produce to ensure you have enough fuel in the case of a boost spike / over boost.

Anyway, i was thinking of running the stock primaries and 2 x ID2000 injectors and will be using 98 octane gas. Will this be enough injector to cover me?

For the fuel pump, i already have a new walbro 255 but am having doubts about running it and am thinking maybe I should step up to the Walbro 400lph?

Im a bit confused and not quite sure if the walbro 255 is good for 400 rotary rwhp or 500rwhp? Either way it seems like it may be a little close for comfort? What does anyone think?

I would rather get the big 400lph pump and call it a day, over running two 255's. I don't want to deal with plumbing/wiring of two fuel pumps.

So to cut things short are stock primaries & 2 x ID2000 injectors, and (either a walbro 255, or walbro 400lph) a good match for my BWS360?

My gut feelings are that the injectors should be a good match, and I should go with the walbro 400...

looking for confirmation.
thanks!

Last edited by 96fd3s; 03-01-15 at 05:48 PM.
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Old 03-01-15, 06:56 PM
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as per BW comp map the turbo can make 69 pounds per minute max at 60% eff.

you need 6.9 pounds fuel per minute at 10.0 AFR

6.9/6.35 = 1.086 gallons per minute (4110 CC/Min) Net into the motor max

given you want to run no more than 85% duty cycle and lag removes 13%...

1.086 X 1.35 = 1.466 GPM = 5550 CC/Minute of nominal/Gross injector capacity

you have 5100, maybe more as the 2000 injectors perhaps flow 2200? either way close enough as to injectors.

as to pump.... Walbro gas pump #9000262

at 20 psi boost and 43.5 static pressure will do 5678 cc per minute

at 30 psi and 43,5 static will do 5236

since you need 4110 net into the motor you are fine...

assuming you have 13.5 Volts. you must hardwire the pump and check it w a multimeter.

howard

Last edited by Howard Coleman CPR; 06-24-15 at 01:15 PM. Reason: testing
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Old 03-01-15, 07:08 PM
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Originally Posted by Howard Coleman CPR View Post
as per BW comp map the turbo can make 69 pounds per minute max at 60% eff.

you need 6.9 pounds fuel per minute at 10.0 AFR

6.9/6.35 = 1.086 gallons per minute (4110 CC/Min) Net into the motor max

given you want to run no more than 85% duty cycle and lag removes 13%...

1.086 X 1.35 = 1.466 GPM = 5550 CC/Minute of nominal/Gross injector capacity

you have 5100, maybe more as the 2000 injectors perhaps flow 2200? either way close enough as to injectors.

as to pump.... Walbro gas pump #9000262

at 20 psi boost and 43.5 static pressure will do 5678 cc per minute

at 30 psi and 43,5 static will do 5236

since you need 4110 net into the motor you are fine...

assuming you have 13.5 Volts. you must hardwire the pump and check it w a multimeter.

howard
Thank you good sir!
I shall proceed.
Cheers
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Old 03-02-15, 04:50 PM
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the ID2000 will flow much more fuel with pressure. So even if you bump up fuel pressure base by 5-10psi it will help your situation considerably.
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Old 03-02-15, 05:53 PM
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Originally Posted by rx72c View Post
the ID2000 will flow much more fuel with pressure. So even if you bump up fuel pressure base by 5-10psi it will help your situation considerably.
Thanks
Walbro 400lph pump is now ordered and I will hopefully get the ID2000's ordered over the next week or something.
It feels good getting the right stuff and not having any doubts about my parts

my 2 x tial wastegates are here (by the way, you were the one who pushed me over the edge to do it properly and go twin gate) so now im just waiting on the manifold untill I can have a nice assembly to look at while I continue buying the rest of the parts..

Last edited by 96fd3s; 03-02-15 at 05:55 PM.
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Old 03-09-15, 06:15 PM
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Hey guys, question, rather then starting a new thread & creating clutter I figured id ask here...

Still re the fuel system, Im getting ready to order my fuel rail & injectors and I didn't realize there were multiple size options/configurations for the injectors & rail.

I was thinking I might go with the full function engineering fuel rail (and id2000s), but I notice there are 3 different injector sizes & 3 different fuel rail configurations for 34, 48 & 60mm injectors.

My question is...well..which one should I get? I don't know the pros/cons re going with one or the other or why one would pick one size over the other...

Im converting to single from a stock twin turbo system, and I don't think I will be keeping any kind of emissions equipment if that makes a difference re the best choice for me.

Also, should I get -6AN or -8AN fittings? im guessing -6AN would be fine?

thanks guys
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Old 03-09-15, 08:44 PM
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6AN is fine. 48mm length rail height is best so you eliminate the adapters that comes on the ID injectors. Have you considered this fuel rail system?

Cj MotorSports FPD Rx-7 Fuel System
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Old 03-09-15, 09:51 PM
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Thanks, that's a really good looking kit there.

I had not considered it, but unfortunately it works out too expensive as due to the value id get taxed to hell on it.

I was going to purchase just the secondary rail from overseas, then get the injectors locally. That way I wont get taxed on any of it. The injectors for some reason seem to be cheaper here as well.

(they cost $300 nzd each here locally, or about $239 USD online. $239 USD = $326NZD, then I would also have to pay shipping on-top of that, and 15% tax on the total value as well.)

Is there a more basic CJ kit?
I don't really mind what brand I end up with, I just want something that's proven

cheers
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Old 03-10-15, 12:48 AM
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Define basic? Like just a secondary only rail ? Yes we have that, when time allows I will get them loaded on the site...
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Old 03-10-15, 02:40 AM
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Old 03-10-15, 02:23 PM
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So the CJ Motorsports one is the one to go with? Not FFE? and 48mm is the go.

Originally Posted by Turblown View Post
Define basic? Like just a secondary only rail ? Yes we have that, when time allows I will get them loaded on the site...
Ok, ill message you soon(probably a couple of days) and maybe you can sort that out for me Don't need to add it online if your busy, we can do it via PM.

Would like to support those who support the forum

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Old 03-10-15, 05:07 PM
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Thanks! Just so its clear we are actually the sole distributor for CJ motorsports Rx-7 parts. So we aren't just a place whoring stuff around, I am doing a lot of work back and forth with CJ. They now have all of the CNC machines in house, and Charles is quite a skilled machinist. I have operated hand lathes and mills, just enough to get myself into trouble, so I can appreciate the work they do. Below is an example of the built in Y fitting for the those looking to do parallel fuel systems, also see the built in R35 FPD into the FPD rails. These are parts not offered anywhere else. Nothing on the market comes close.
Attached Thumbnails Enough Fuel pump & injectors?-cj-y-fitting.jpg   Enough Fuel pump & injectors?-cj-motorsports-secondary-rx7-rail.jpg  
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