Cartech FPR or Vortech SFMU?

Okay, does anybody have any experience with either of these and if so, which would you recommend? I am going to be installing a Jackson Racing supercharger in the next couple of weeks and have narrowed my fuel management down to one of these two. The Vortech SFMU seems more adjustable, according to their website, but not sure about the reliability of the unit.

Thanks in Advance,

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Best Regards,

Darren D. Wall
darrenwall@netzero.net
kirbyator@yahoo.com
1995 Civic DX HB
Go: Gude, AEM, DC Sports, Weapon-R, 5-Zigen
Turn: AGX, Tenzo-R, Pirelli
Look: PPG, APC, Wings West

i'd pick the cheaper one, since they both work off the same principles and internally are for all sakes and purposes, equivalent.

you are aware that these units will give you real High fuel pressures right? You will need a large pump or a secondary pump inline in the fuel system

I am installing a new fuel pump at the same time. The reason for using a different fuel pressure regulator than comes with the supercharger is exactly that, to keep fuel pressures down. The rising rate regulator that comes with the JRSC kit adds 5 psi fuel pressure for every psi boost. So with 6 psi boost from the supercharger, it adds 30 psi of fuel pressure.

I already have higher flow injectors than stock as well as a modified ECU that changes the injector duty cycle above 4000 rpm, so I don't think I will need that high of fuel pressures to get the proper air/fuel ratio. The Cartech or Vortech unit will allow me to set the fuel pressure rise, anywhere from 1 psi per lb boost to 7-8 psi per lb boost.

My understanding is that the stock fuel system is good to around 60-65 psi, at which time the lines are stressed and the injectors reliability will drop. My current static pressure is about 30, so adding 30 psi at 6 lbs boost would put me near the limit. But, again, I don't think I will need that high of pressure due to the larger injectors and modified ecu.

----------
Best Regards,

Darren D. Wall
darrenwall@netzero.net
kirbyator@yahoo.com
1995 Civic DX HB
Go: Gude, AEM, DC Sports, Weapon-R, 5-Zigen
Turn: AGX, Tenzo-R, Pirelli
Look: PPG, APC, Wings West

Originally posted by darrenwall
I am installing a new fuel pump at the same time. The reason for using a different fuel pressure regulator than comes with the supercharger is exactly that, to keep fuel pressures down. The rising rate regulator that comes with the JRSC kit adds 5 psi fuel pressure for every psi boost. So with 6 psi boost from the supercharger, it adds 30 psi of fuel pressure.

I already have higher flow injectors than stock as well as a modified ECU that changes the injector duty cycle above 4000 rpm, so I don't think I will need that high of fuel pressures to get the proper air/fuel ratio. The Cartech or Vortech unit will allow me to set the fuel pressure rise, anywhere from 1 psi per lb boost to 7-8 psi per lb boost.

My understanding is that the stock fuel system is good to around 60-65 psi, at which time the lines are stressed and the injectors reliability will drop. My current static pressure is about 30, so adding 30 psi at 6 lbs boost would put me near the limit. But, again, I don't think I will need that high of pressure due to the larger injectors and modified ecu.



the RR FMU will not be useful then...have you seen them in action yet? They really project the pressure up(with any disc you use).

As for the FPR that comes with the JR kit, both of my buddies with the JRSC got one just like any other non-boost dependent regulator. I can't speak for you though.

If you already have higher flow injectors, just run the JR FPR and turn the pressure down with that....

Did you say the Vortech FMU is worthless? If so, what is a good boost dependent regulator to use?

Thanks...

I was actually looking at Vortechs "Super" FMU, which doesn't require the disc to be replaced to change the fuel pressure rise rate. It is adjustable from 1 psi fuel pressure raise per lb boost to 7-8 psi fuel pressure raise per lb boost.

sleeperteg: a good fuel setup for boost would be higher flow injectors with any FPR that can adjust fuel pressure tuned on the dyno.

darrenwall: I thought you meant the ones that come with the turbo kits...

Hello all, this is my first post here. I am still in mostly a lurking stage, but the subject of this question relates directly to something I want to make sure I understand. I plan on going FI in the future, and I need to sort all of this out. ;)

Corky Bell's Turbo book has very specific advice on fuel management systems. In the case of fuel management, turbo is the same as supercharging, because we are really just talking about boost pressure in this context.

Corky states that fuel enrichment based on boost pressure is "technical nonsense". Isn't the Cartech and Vortech FMUs basically fuel enrichment devices based on boost pressure? These devices fall down, as I understand it, because it adds the same amount of fuel at all RPMs, based only on boost pressure. So the amount of added fuel at 3k RPM is the same as the amount of added fuel at 7k RPM, as long as the boost pressure is the same. That doesn't sound right to me. :confused:

I thought that the only true way to get accurate fuel management under boost is to :
[list=1]
Run injectors large enough to sustain stoich fuel levels at redline at top boost pressure
Run a reprogrammed ECU to control the larger injectors
[/list=1]

Am I wrong about this? If I interpret Corky's book correctly, this is what he says also.

More comments welcome.

Originally posted by Artifex
Hello all, this is my first post here. I am still in mostly a lurking stage, but the subject of this question relates directly to something I want to make sure I understand. I plan on going FI in the future, and I need to sort all of this out. ;)

Corky Bell's Turbo book has very specific advice on fuel management systems. In the case of fuel management, turbo is the same as supercharging, because we are really just talking about boost pressure in this context.

Corky states that fuel enrichment based on boost pressure is "technical nonsense". Isn't the Cartech and Vortech FMUs basically fuel enrichment devices based on boost pressure? These devices fall down, as I understand it, because it adds the same amount of fuel at all RPMs, based only on boost pressure. So the amount of added fuel at 3k RPM is the same as the amount of added fuel at 7k RPM, as long as the boost pressure is the same. That doesn't sound right to me. :confused:

I thought that the only true way to get accurate fuel management under boost is to :
[list=1]
Run injectors large enough to sustain stoich fuel levels at redline at top boost pressure
Run a reprogrammed ECU to control the larger injectors
[/list=1]

Am I wrong about this? If I interpret Corky's book correctly, this is what he says also.

More comments welcome.

you pretty got it down....

maximum boost is a great book BTW, I highly reccomend it

This may be another stupid question then, but what is with this thread? Why are we talking about FPRs when they can't cut the mustard? Shouldn't the correct reply be : "Get a Hondata (or some similar)" ?

For that matter, does JR expect people to be happy with just a new FPR shipped with the kit? Is that their idea of proper fuel management? That is amazingly dangerous of them to have that attitude. It's a wonder that JRSC cars don't blow up every day (maybe they do :silly2: ).

Darren: I've never actually done this before, but all the information I know of tells me to get a complete, integrated replacement ECU for your car. The Hondatas are very popular for this. Since you are a soon-to-be SC owner, I highly, highly reccomend getting Corky Bell's Supercharger book (you can find it on Amazon). There is so much in there that is basic knowledge, even if you already own a kit.

Gook luck and let us know how the install goes.

I think technically your right, and wrong. The FPR really just tricks your injectors into injecting more fuel based on boost. How much fuel you inject is a function of fuel pressure AND injection pulse. The ECU controls the injector pulse based on throttle position, RPM and several other factors. On a stock Honda, you get more fuel at higher RPM's because the ECU lengthens the injector pulse.

The only new addition here is boost, which will require more fuel per each psi boost. You will get more fuel at 6 lbs of boost and 6000 rpm than you will with 6 lbs of boost at 3000 rpm, because the injector pulse will be longer at 6000 rpm (due to the ECU).

That said, yes a proper programmed ECU is the better option, it will be able to better follow the fuel requirements of the engine as well as react quicker. The reason most "boost vendors" (turbo and supercharger alike) don't provide new ECU's is they are expensive. AEM's new standalone is $1400, and its about half what other systems cost!

The way they make "piggyback" systems safe is too keep the system overly-rich. Providing too much fuel cuts the power gains down, but prevents engine-breaking lean conditions. All the vendors that sell turbo/supercharger kits do this some way (Jackson Racing, Greddy, A'Pexi, FMAX). I don't believe Drag even sells fuel control with their turbo kit, they leave it solely up to the purchaser to determine how to manage fuel.

The downside to a Hondadata is you need to either have them program it for your car on their dyno, or buy the programming software and program it yourself on a dyno. I don't have a dyno nor the $1000 to get enough time on one to properly program it.

For now, I have to go the piggyback route, which won't give me the best fuel ratios or power, but if done properly, will be safe.

Darren:

I've got the Cartech 2025 FMU and will be installing it this Mon when I go to 8psi on my JRSC.

Now for which one to go for is up to you. With the Cartech, at the stock 6psi setup, it is good. It eliminates the dread tip-in detonation by raising the FP before the onset of positive manifold pressures. It is also good because it replaces the ever s faulty JR FMU. It is known to crap out or stick making FP readings look wierd. You can use the Cartech in conjunction with an aftermarket FPR (AEM) or your stock one.

The Vortech SFMU basically does the same as the Cartech but you can remove the stock/aftermarket FPR out of the fueling equation. It can basically do double duty.

Both units can be adjusted if you decide to increase your boost and add larger injectors to reduce your FP.

for artifex, just so you know, at our altitude, 5800 ft, there have been a few cars with just the jrsc kits, no other fuel mods except for their fpr, that have blown engines due to detonation. This is probably an altitude thing, but you are correct that the fpr isn't a suitable answer.