I just did some calculations on injector size and the flow rate of the walbro 255hp fuel pump. my results are cause for alarm. i hope i'm wrong.

it seems to be common practice to get a 12:1 fmu and raise fuel pressure as high as 110 psi in hopes of increasing flow through the stock injectors. this would work fine if the fuel pump had the same flow rate at all pressures, but it doesn't. as you increase the fuel pressure, the pump flows less GPH (gallons per hour).

the walbro 255hp is capable of the following flow rates:

80 psi: 43 GPH, 2714 cc/min
90 psi: 35 GPH, 2209 cc/min
100 psi: 27 GPH, 1704 cc/min
110 psi: 15 GPH, 946 cc/min

15 GPH converts to 946 cc/min.
that breaks down to only 236 cc/min for each injector!

theoretically, your stock 234cc/min injectors should flow 374cc/min at 110 psi. this number seems to be severly limited by the fuel pumps ability to keep up the flow at that pressure.

this data suggests that we should not expect the walbro 255hp to produce sufficient flow at incredible pressures. if you do, you will run lean and we all know what that means. i would think 90 psi is a reasonable MAXIMUM fuel pressure. that pressure would be capable of feeding 4 injectors at 568 cc/min each. this is enough to support about 285-290 hp. lower fuel pressures would also reduce the risk of injector lock-up. 70-80 psi would be an even better pressure range to operate in.

the trick is choosing the right size injector to flow enough without needing extremely high fuel pressures, yet be small enough to either sneak by the stock ECU or be managable by a S-AFC. I know injectors are a little pricey, but after reading this, do you still want to run your stock injectors at 100 psi or higher?

http://www.rceng.com/

http://www.vfaq.com/pump-Walbros.html

Why does it seem that we are all worried about our stock injectors and how much they can flow with these turbo kits???

here is the deal..they do not flow enough to allow us to run more than about 3 lbs. of boost...they are pushing way too much pressure through a tiny little opening!!!! That causes problems like injector lock up, not too mention the fact that pushing that kind of pressure doesn't allow them to atomize the fuel, all it does is dump fuel into the motor! Yes, it works, but you are cheating yourself if you think it works efficiently...

jason
95 GS turbo

so we upgrade our injectors!! will the injectors from GST/GSX work for us?


l e o n

LAST EDITED ON 28-Jan-01 AT 07:47 AM (PST)

LAST EDITED ON 28-Jan-01 AT 07:16 AM (PST)

Unfortunately there are basically 2 types of injectors, low impedance/resistance (peak and hold) and high impedance/resistance (saturated). We have the low impedance (correct me if I'm wrong) while the GST/X's have the other. The only way to use the high impedance is with the use of a fuel computer (like the Super AFC or Haltech).

BTW, I believe the first post about the Walbro pump only supplying 234 cc/min of fuel is wrong, I don't have formulas or figures to argue with, but if all the GST/X owners upgrade to this same pump, or a variation of (the Nippon Denso pump flows at 255 gph also) as well as this same pump is good for a Mustang GT (2 times the numer of cylinders as us) then this should be good enough for our turbo charge needs... (once again, correct me if I'm wrong)...

DoN

'99 GS Sports Edition
Star Stage 2, CFDF Clutch
Greddy Manual Boost Controller
Greddy BOV and EVO Exhaust
Greddy TT and shift knob
B&M Edge Short Shifter
Eibach Sportlines with Tokiko Blues

Good post - rigtht idea, just mixed up injectors - we have saturated, GS-T have peak and hold - we can use the peak and hold if using a proper ecu like HRC's Accell

MuRiX
97 Eclipse GS HRC Stage II
And a whole lot of other mods...
89 Accord LSi - yes it's mine :(
http://murix.home.icq.com/index.html

Thanks for clearing that up...

Don

'99 GS Sports Edition
Star Stage 2, CFDF Clutch
Greddy Manual Boost Controller
Greddy BOV and EVO Exhaust
Greddy TT and shift knob
B&M Edge Short Shifter
Eibach Sportlines with Tokiko Blues

jason, i'm NOT worried about trying to use the stock injectors. i thought i made it clear that i think it's a bad idea. if you need that much more fuel, it's time to call RC Engineering and order some new squirters.

don, i'm saying that if you try to run the walbro pump at 110 psi, it will only flow 946 cc/min. (236 x 4) if the GST guys are upgrading to the walbro pump and running it at these insane pressures, then they are cheating themselves out of fuel too.

there is NOTHING WRONG with the walbro pump. it is plenty adequate for supplying fuel to a turbo'ed 420A. the problem is that asking the pump for 110 psi is expecting too much.

run the walbro at 80 psi and you'll have enough flow for 4 injectors at 678cc/min each. that should be enough, eh?

moral of the story: get new injectors and a S-AFC if you're going to run more than a few pounds of boost.

This thread elaborates upon the inadequate fuel flow aspects of the Walbro pumps that I brought up recently.

A correct conclusion: use a pump that can keep up with the demand at hi pressure. The stock injectors have shown themselves to work well in our HRC turbosystem installations with a correct fuel supply such as our ACCEL pump.

The Walbro pump, as I mentioned earlier, is adequate for factory turbo applications (GS-T, GS-X) which never see more than 65-70 PSI pressure. It is NOT adequate for VROG equipped installations such as our 420A turbo cars, as it was never intended for such high pressure delivery.

Please DO NOT try to run at a lower fuel pressure under boost as mentioned in this thread. If HRC customers have further questions about these issues (although they have nothing to worry about, since their systems come with a properly engineered fuel setup), they can contact HRC Tech Support daily at 630-801-9065.

please re-read my posts carefully. i did NOT recommend simply turning down the fuel pressure and leaving everything else the same. that would certainly kill your engine.

i suggested getting larger injectors and a S-AFC so you wouldn't have to run such ridiculously high fuel pressures.

440cc/min injectors wouldn't need 110 psi to flow enough fuel, correct?

sure you can get the accel pump if it can supply enough flow at those pressures. i don't have the specs on that pump, but if you say it can supply enough fuel, i'll take your word for it. i was simply stating that it's a bad idea to run the walbro at 110 psi with stock injectors and think everything is fine. it's not.

that's all i'm saying.

I did understand your intentions, but I feared that others who read the posts might not.

Thanks for clarifying that one would also need larger injectors to consider running lower fuel pressures.

Not trying to knock STAR - just making a point here - this is what happens when you just throw a kit together without real development and testing ....

MuRiX
97 Eclipse GS HRC Stage II
And a whole lot of other mods...
89 Accord LSi - yes it's mine :(
http://murix.home.icq.com/index.html

Also, for Hoot's benefit, the HRC kit uses a TWO FUEL PUMPS.

HRC retains your stock fuel pump, and then also uses the in-line accel pump. I guess both of those pumps in tandem supply all the needed fuel to run 110 psi of fuel through 235cc fuel injectors.


Jason
98' Eagle Talon ESi-T
Mitsu Super 16g Turbo(HRC)


http://springfielddsm.homestead.com/JasonsPics.html

HRC, can we order the in line pump kit? =)


l e o n

i just want to say that it was definately not my intention to discredit any kit manufacturer. as more of us go turbo, some will try to build custom kits or mix-n-match parts to try to get the best of both worlds or to be 'one-up' on the guy down the street. i just wanted to point out a potential trouble area that could be easily avoided by doing a little home-work.

Ok, here is my take on this whole topic of fuel pressure, larger injectors, and shotty fuel pumps.

Obviously, HRC has done the most amount of homework on their kits. But, i still disagree with how either of the setups can truly be good. You are pushing in excess of 100 lbs. of fuel pressure through injectors not really meant to see over maybe 60-70 lbs. Does it work? Yes. But, at that kind of pressure, it can cause injector lock up, leakage, and i would assume injector failure. Something i don't think you would want to see on a turbo car.

So, my opinion on what would remedy this...

stock block--Well, it seems chris has a setup that works pretty well doesn't he? he even has dyno's to prove it. You want to get something safe and reliable for 10-12 lbs. of boost? Get some 400 CC injectors, a super AFC, and an adjustable FMU if you bought the star kit. turn down the base idle pressure so the AFC doesn't have to do as much work, set it at a lower gain rate than the typical 12:1, and use the AFC to fine tune everything? Chris, am i correct in this is how your car is setup?

if you want to safely run 10 lbs. and not deal with the electronics, get the 310 CC injectors that our computer can compensate for, or at least supposedly compensate for. I'd really like to know if this truly works right or not.

Built motor--well, if you don't plan on racing it and trying to hit the 11's, then the setup above would probably be quite adaquate. But, if you want to get to where Hahn is at, you are gonna need a setup similiar to hahns, which is the accel DFI that comes with their stage IV and V kits. The other option is a standalone like the haltech. I am opting for a haltech e6kbecause you can tune the timing as well as the fuel. I have one ordered, and hope to have it ready to be installed by spring. I will definitely keep you posted on how it goes. But to seriously be able to get enough fuel to run those kind of numbers like i know people like wyatt are trying to do, you are gonna need some large injectors, like 625's (hahns) or some 660s or 720s. There is no real way to control injectors this large without a standalone? am i correct HRC?

My ideal setup would be a sheet metal intake manifold with 8 injectors, 4-310 cc's to run at normal off boost operation to keep it more streetable, and 4-550's for boost. Then use the haltech to controll it. Would make for a pretty intersting ride i would think.

ANyway, i have rambled on here long enough, if anyone wants to correct me on any of this, i would be glad to hear it.


jason
95 GS turbo


hehehe...beater car...

I JUST read that 8 injector setup somewhere, Jason. Maybe the neon boards??

We've been slumbing in the same districts, I see. hehehe. I know from I prior aim chats that you've definitly done some homework on this.

The bottom line though on running the +100psi of fuel through the stockers is that it's at least been tested by HRC. Some people refer to this happening, but I have yet to hear of an instance of it occurring. (not saying it sin't possible, maybe just unlikely) I know that many are running high amounts of fuel with the HRC kit and all is going well.

I myself like the sounds of bigger injectors(440cc) and some S-AFC help.


Jason
98' Eagle Talon ESi-T
Mitsu Super 16g Turbo(HRC)


http://springfielddsm.homestead.com/JasonsPics.html

Yeah, i see we are playing around here at the same time. Like i said, HRC has done their homework which is great, i wish star would have done theirs as well, but for the price difference, i guess i can see why. Whether or not it will happen, is something i can't say. I have read it can happen, and i bet if you ask some honda kats who seem to have been turboing cars alot longer than us, i bet they will say it can happen. But, only time will tell, but, since i plan to do a haltech, i ain't gonna worry about it.

as for the 8 injector deal..alot of racers do it. like brent rau? you guys know him right, or sean glazar?

jason
95 GS turbo

LAST EDITED ON 29-Jan-01 AT 02:37 PM (PST)

hey 95esi,

I think HRC had already posted that they were making their fuel system available to the public. You can choose to just get their fuel pump, or the whole shabang, I think. Anyhow, here's the string I was talking about:

http://www.2gnt.com/dcforum/DCForumID16/170.html

And Hoot,

I don't think anyone including HRC thinks you either intentionally or unintentionally discredited any kit. If anything, I think you have done an OUTSTANDING job illuminating many of us with your fuel pressure figures, including myself. Besides, I've been trying to find some answers or clues as to why it seems like "more" STAR kits had a tendency to detonate as opposed to HRC owners. IT seems you may have stumbled upon a sort of "breakthrough" for us. Knowledge is power, my friend. So I think some people can "owe ya one." As a matter of fact, thank you.

We just gotta pick on you Avenger owners is all. ;-)


Jason
98' Eagle Talon ESi-T
Mitsu Super 16g Turbo(HRC)


http://springfielddsm.homestead.com/JasonsPics.html

Hell yes, Hoot! Good info. Please forgive my tone if I came off "superior"; I am always on the lookout for ways to keep my boyz out of trouble.

Thanks for bringing this issue further into the open!

And as for the question from Jason 95 GS about standalone systems being required to run large injectors: Yes and no. How's that for definitive!

But seriously: we use an ACCEL-DFI, which is a standalone. This setup can control virtually any size single injector, or staged operation with two sets of injectors. We use it for anything above 500cc injectors on these cars. On Len's Neon, it controls 800cc injectors and also controls / provides fuel enrichment for the car's 100 HP stage of N20.

thanks for the praise guys.

"you like me... you really like me." remember her? LOL

but to get the record straight, i own a SEBRING! ;)

LAST EDITED ON 30-Jan-01 AT 03:43 AM (PST)

stock block--Well, it seems chris has a setup that works pretty well doesn't he? he even has dyno's to prove it. You want to get something safe and reliable for 10-12 lbs. of boost? Get some 400 CC injectors, a super AFC, and an adjustable FMU if you bought the star kit. turn down the base idle pressure so the AFC doesn't have to do as much work, set it at a lower gain rate than the typical 12:1, and use the AFC to fine tune everything? Chris, am i correct in this is how your car is setup?



Yeah that sounds right. Fyi, its turned down to 35psi at idle. But damnit, I'm running 17psi, pump gas, daily driven, HRC sidemount!!! And quite hard I might add. I never take it easy on my car.

You think I will last like this Bill? I mean this fuel setup at this high boost. I can't let Armond and his 'Avenger' get too much faster than me or it will go to his head and all those other Avenger guys ;-). I already enjoy whooping up on his almighty Stealth Twin Turbo :) Am I going to make it on race gas with this setup and 24psi? I was originally thinking of just going to a 500cc or something like that and use the AFC. Perhaps I should start looking into the Accell myself.

MuRiX
97 Eclipse GS HRC Stage II
And a whole lot of other mods...
89 Accord LSi - yes it's mine :(
http://murix.home.icq.com/index.html

did u rebuild your bottom end to run 17 psi?

l e o n

Hrmmm.

I think I did....
From my webpage under mods....

Performance Mod's:

Engine:

HRC Super 16G
HRC sidemount intercooler (ApexI FMIC IC to go on soon)
HRC upper/lower IC piping
HRC exhaust manifold
K&N intake
AEM cam gears
Copper Head gasket
Crower Rods
JE 8.8:1 Pistons
Port/Polish
Blueprint/Balance
Blitz BOV

Ignition:
NGK BKR6E
NGK 8mm Wires
Optima Blue top
MSD DIS-2

Exhaust:
Custom 2.5" downpipe
Tanabe G-Medallion 70mm cat-back exhaust

Fuel:
Inline Fuel pump
Adjustable Fuel Pressure Regulator
400CC Fuel Injectors
VC-1

Electronics/Gauges:
ApexI Super AFC
Greddy Profec B
Blitz FATT
PSI boost guage
Autometer A/F gauge
Autometer EGT

Transmission:
Custom carbon-kevlar 4-puck clutch - non-modular
Short shift kit

Suspension:
Energy Suspension Polyurethane Motor mounts
H&R Sport springs
Tokico adjustable struts
Ingalls Camber Kit front
RRE Camber Kit rear
Front/Rear Strut Tower Brace (Lower tie bar on the way)
TSW Revo 17x8
Falken GRB 225/45ZR17

Brakes:
GSX 2-Piston Calipers
Powerslot Rotors
MetalMaster brake pads

Crap that doesn't help my performance-

Trust Blue Shift knob
Trust Blue Oil Cap
Goodridge Blue Silicone Hoses
Racing pedals
Ignited starter button
Carbon fiber dashkit
NR white face gauges
Eclipse by Fujitsu Ten CD Player
Alpine alarm system
Smoked taillenses
Clear corners
Projector headlights

Most of this was done since 99. I have a new round of mods to do before the shootout, mainly for some more traction :(

MuRiX
97 Eclipse GS HRC Stage II
And a whole lot of other mods...
89 Accord LSi - yes it's mine :(
http://murix.home.icq.com/index.html

Murix: As long as you are able to achieve correct A/F ratios with your setup under boost, you should have no problem. I can help determine more tuning parameters for you if you email me: eng@turbosystem.com.

is it possible to just run the Accel fuel pump with the star kit and just sell the walbro that comes with it? would this solve the injector problem and allow 10-12psi? shouldnt this be considerably cheaper than buying $350 worth of injectors and then a SAFC, plus you cold install this from the get-go and get the correct fuel setup that HRC picked to run the perfect star setup, problem-free (this seems to be the only problem with the star kit ive seen so far)
http://www.geocities.com/blue2gnt
blue2gnt@hotmail.com AOL IM - ThreeRedDiamonds

Of course you could use an inline instead of the Walbro in-tank, but hell, you could just run the Walbro and the Accell... that's what I would do if I already had a Walbro in-tank (which I will, and from what I'm hearing, I may also get one of these accell units too).


1996 Eclipse RS / 5-Speed / Body Components by Aerogear / Coated in Magnetic Red Metallic v2 - More at http://home.insightbb.com/~mgalyan/
Mark Galyan - Greenwood, Indiana

Who are you talking to? This thread is 2 years old :wary

c'mon now. At least someone is searching the archives. :thumbsup


95 Eclipse RS : 5 speed
Jeep TB writeup - http://www.dimensia.com:81/jimbo/JeepTBfor2gnt.html

HAHAHAHA
This is too funny...

Nick

What the hell... how did it get to the top of the list... didn't even look at the dates...

1996 Eclipse RS / 5-Speed / Body Components by Aerogear / Coated in Magnetic Red Metallic v2 - More at http://home.insightbb.com/~mgalyan/
Mark Galyan - Greenwood, Indiana

Whoa. Old school thread alert.

word up

Well somehow this got to the top of the list, and I didn't pay attention to the dates, lol. Anyway, this is a great post. I had no idea that the Walbro 255 would be insufficient with stock injectors at higher boost levels. Guess I'll be ordering 30# injectors with my kit from Motofool.... only like 90 bucks more anyway, and I won't have to buy a SAFC or e-manage yet.


1996 Eclipse RS / 5-Speed / Body Components by Aerogear / Coated in Magnetic Red Metallic v2 - More at http://home.insightbb.com/~mgalyan/
Mark Galyan - Greenwood, Indiana

That's the whole point of this thread - the 255 is fine at 5-6psi (stock STAR boost) but anything more and it can't flow enough at those pressures. Bigger injectors, with lower pressures, and you're once again back in the acceptable range in with the 255.

I can't beleive this thread is already two and a half years old..

About how much pressure would you need @ 8 psi of boost with 310cc injectors? How do you find out these numbers anyway?

1996 Eclipse RS / 5-Speed / Body Components by Aerogear / Coated in Magnetic Red Metallic v2 - More at http://home.insightbb.com/~mgalyan/
Mark Galyan - Greenwood, Indiana

>About how much pressure would you need @ 8 psi of boost with
>310cc injectors? How do you find out these numbers anyway?
>

check out Corbin's site
http://www.geocities.com/vttalon/tech.html

This was obviously pre "corbin's-fabricate-o-rama"