I have been seriously considering purchasing a Bosch fuel pump (from Endyn). The RealTime guys use Bosch fuel pumps so it must be worth the expense and I'm sure they are not running 12:1. Have any of you with big kahona compression upgraded your fuel pump and injectors? Do you recommend Bosch or any other?

Secondly, have you used an in tank pump or external inline?

 

You only need a fuel pump if you really require a lot of fuel or high fuel pressure. I'm sure with ecu tuning and bigger injectors the stock fuel pump should hold up just fine.

 

Fast94gsr what compression are you running? I just like my engine to last so can I ask ? : What's your rationale for thinking the stock fuel pump is ok with 12:1? I just like to understand why people do things as opposed to accepting a statement...call me skeptical....

 

my guys at aj tell me to keep fuel injectors and fuel pump. even stock pressure and you can get enough fuel to your engine. I am running 12.5 compression too. we'll see on the dyno, but i dont' think i am running lean.

 

STOCK Fuel Pump is plenty

__________

97 R 58
01 F150 5.4 Supercrew
97 M3 4 Dr

 

hey Michael,

I run about 11.4:1 compression. I have a skunk ecu which is a very rich program, stock fuel pump, and stock injectors along with a vafc.

Judging by the air fuel meter which was hooked up to the dyno I didn't require any extra fuel. I verified by looking at my a.f ratio which was dialed in at around 13:1.

 

only if you run high hp and/or high pressure do you require a better fuel pump.

Compression ratio has no bearing on fuel pump selection

FYI, I am using the bosch pump, but I am also running 370cc injectors at
75psi. But soon 450-550cc injectors and my problems will be alleviated.

 

what is considered high hp and high pressure?

 

Most of us run our cars on the street where full throttle runs will never extend beyond 2 minutes or so and for some never beyond 15 seconds.

The use of the bosch pump is most likely for relability and consistancy. Running full throttle constantly is taxing on the stock pump especially since the Real Time cars are making about 40hp more than stock. For example in Japan the N1 cars have to use stock engines and the only mods allowed is an ECU upgrade and exhaust (stock header) but those guys use upgraded fuel pumps. The main reason being reliability under those racing conditions.

I know guys that ran low 13's all motor (back in 1996) with stock pumps in hybrid civics that originally came with 100hp engines.

 

high pressure anything over 75psi high hp i'm taking a guess anything over 220 hp.

stock fuel pump would probably burn up if kept at that high pressure for long sustained durations..

 

My .02

I'm running 12.0:1 compression, 210 whp, 430cc injectors, stock fuel pump (99 Si) and stock fuel pressure. I have no loss of pressure running up to 9500 rpms.

HTH

BTW, what Steve said, stock is fine until you start upping the pressures

 

jezass christ, 430 cc injectors? Arent' those just a little too extreme for your application? Does your car even idle? I mean damn i know guys that use those in turbocharged applications..I can't see why you need such a large injector if you're only making 210 hp..Call me ignorant but I can't figure out why.

 

Stephen: I presumed that fuel delivery requirements prevented detonation, dependent of course on mixture quality in the combustion chamber. At higher peak cylinder pressures with 12:1, I presumed that delivering more fuel via a pump would be an insurance policy I want to take out.

TodaSi: I'm assuming Dan and you are of the philosophy that increasing fuel injector size at lower fuel pressures is the best way to ensure reliable fuel delivery under high detonation risk conditions. Stephen is running a fairly hefty injector size as well but has also used a fuel pump upgrade to back up the injectors, since they require higher than stock range fuel pressures (I'm again guessing here what he considers as "high"). I'm wondering if the quality of spray/atomisation decreases with bigger injector size and use of a stock pump? I'm thinking of the analogy of priming with more "top up" fuel pressure before getting to the injector by using a pump has to be better than pinching down the hose to get more pressure going to the injector. Are you getting any washing down or separation of fuel from the air-fuel mix?

Adding a fuel pump regardless of fuel pressure is insurance just like getting good valvesprings. Pushing parts to their maximal tolerance all the time cannot be good for longevity. I'll be running 270 cc/min saturated injectors with 12:1 compression and from what I see around here people like 310 cc/min injector sizing as a minimum for that air delivery capability and compression combination. So to get the same flow as 310's at 80% duty cycle max., approx. 55 psi FP is required on the 270's at 80% duty cycle max. So maybe I won't need a fuel pump as you suggest. My goal is 200-210 whp. Not like you guys who have 215+ power.

The idea of running lower FP's and less duty cycle (more reserve) to get the same flow required appeals to me. Unlike many here, my budget is not limitless and an engine lasting by running with more reserve at hand is one of my goals.
Thanks for all your input .


[Modified by Michael Delaney, 11:38 AM 8/2/2001]

 

That's for the afterburners that he has on his car.

 

I am running a 1 point higher and a bigger motor using 370cc, 430 I think is a little too big. But is all depends on how your fuel mapping, injector duration and pressure. Stock fuel pump and regulator, ECU, etc too big of the injectors will make it run like ****. So is all depends on the fuel mapping setup.

________

97 R 58
01 F150 5.4 Supercrew
97 M3 4 Dr.

 

Stock 240 cc injectors and stock B DOHC fuel pumps have been proven to supply up to ~210 whp. Anything more it is better to get bigger injectors and drop the fuel pressure some (for more flow) but you can stay with the stock pump. However if the stock pump has some milage already, I would suggest walbro pumps (a true easy factory sized replacement) which are fine for NA.



[Modified by frank@b16a.com, 1:10 PM 8/2/2001]

 

For hybrid guys, a lot of them upgrade their crappy old ones to GS-R or R pumps with great success. But not too many go 200+ all motor.

I'd say go for it T, you are one who likes to go better safe than sorry, and it certainly isn't a bad idea!

 

I'd like to formally thank asterix for linking me to this site:
http://www.hondata.com/techfuelpump.html







You also learn a lot when you chat with Russ Collins too...there's wisdom . I recommend it to anyone and RC is pretty down to earth.

Well since I couldn't get Stephen to answer my question, this seems to be quite an eye opener. Interesting that the stock Honda pumps max out at 75 psi (internal bypass valve in pump) and 200 flywheel hp. Also interesting is the heat production associated with running at higher pressures.

That pretty much cinches it for me...I'm getting the pump. stock FP, less heat, more power potential...cheaper than a set of 550 cc/min injectors too!

cheers

BTW to the earlier post: we were talking about piston compression not air fuel ratio.

 

To answer a few of your questions, which have been partially answered by the information provided by Hondata already, as to why we are running 430cc injectors.

We are of the philosophy of running a larger injector @ stock pressures and cranking back on pulse-width. This avoids heat build up, injector failure, longer duty-cycles, and maintains the design parameters of the injector. (i.e. pushing beyond 80% duty-cycle)

As for fuel atomization, we have not had any evidence of poor atomization, the 430cc injectors are designed..as every injector is, to run at low duty-cycles...idling comes to mind.

Buying an upgraded fuel pump is always added insurance

Hope I helped

 

I am using a stock 94 civic Si pump on my motor making 216whp. I am rebuilding the motor, and am upgrading to larger 290cc injectors. Havnt decided whether or not to upgrade the pump. The wideband O2 will let me know if its needed when i hit the dyno when im done with the build.

 

Look Tuan,
Fuel pump supplies volume. Until you surpass the volume the pump can supply
then you dont need one. Higher fuel pressures will also necessitate a pump that
can supply volume at higher pressure. You SHOULD know by now that pumps
arent as efficient at higher pressures.

You should upgrade the injectors before going to a larger pump.

Only in cases such as running larger lines and huge injectors or running
higher than stock pressure(which is my case at 75psi) would I change the pump.
The stock pump is quite capable as is shown by all the turbo cars people are
making with stock pumps pushing 250-300whp.

I still dont see how you are trying to correlate pump necessity with compression
ratio. Fuel pumps dont deliver fuel, injectors do. As I stated above, the pump
supplies volume.

As long as you run stock pressure or the pressure the injectors are rated
at(3bar, 43psi) then you will be fine with the stock pump.

 

if you decide to get the Endyn Bosche Mod'ed Pump, don't even think about mounting it in the tank. It was the biggest pain in the ***. The pump is as big as the opening of the hole in the tank, barely fits and you have to secure it somehow which makes the pump assembly bigger than the hole. Not fun. So...take the stock one out, run a line where the stock pump existed and keep the pick-up in the same location as before. Mount the pump with something wrapped around it, the pump is loud, very loud. IMO, it's a bit hardcore, probably too big, but I was dumb enough at first with my turbo to run 90+ psi of fuel pressure with a FMU so I needed a pump. Ditched the FMU, kept the pump, and got a PMS. Now, I'm stuck with PMS with no car to use it on. ahhh.

 

Really?
My bosch is not loud at all.
My old paxton on the other hand..... Dear God.....

 

Stephen,

no offense intended but your answer was sufficiently vague to ask for a clarification of definition.

wrt my fuel pump linkage to compression:

since I'm in the medical field, I'll use the heart as an analogy: cardiac output is dependent on priming of the pump (venous return), pump funtion (inotropy/stroke) , and resistance against which the pump must work. Flow as a function of pressure is volume dependent. So you need a head volume for the pump to have something to work on (not enough priming of the pump and the output is low regardless of how high you want to crank up the pump) . The pump also must overcome resistance to get the fluid to the end organ.

So in a mechanical system, you can't tease out volume from pressure...flow is a volume per unit time. Pressure differentials are indicators of how hard the pump must push to get that flow to the injector. The injector is merely a gatekeeper or control point (like arterioles in the human circulation) . So as you up the volume, you up the pressure at the priming point before the injector.

If volume determines pressure at the injector and pressure dictates flow above the value that the injector is indicated at, then you find that volume affects fuel delivery. Hence the linkage of a pump to fuel delivery and fuel delivery to compression ratio (antidetonation).

sorry, I'm not an engineer.

BTW Larry actually does say that the in line pump is easier to install on the website instructions.

cheers

 

Michael,

What is your setup?