MR2 Owners Club Forum banner

1 - 19 of 19 Posts

·
Registered
Joined
·
343 Posts
Discussion Starter #1
or is that a no go? i just remember someone saying a walbro pump would be good all theway up to 850's so i was just curious if i could still use my stock pump with 550's thanks
 

·
Registered
Joined
·
5,392 Posts
You can but its not safe. If you wanted to get all of the 550's use and use the stock pump you will need to bump up the base fuel pressure a few psi. Use this as a guide:

http://www.mr2oc.com/showthread.php?t=31686&highlight=fuel+pump

Basically you take your base fuel pressure of approx. 40psi and if you are running 20psi of boost, you look at 60psi. At 60psi that graph will tell you if your pump can keep up or not at those HP levels. It shows at 60psi that 300rwhp is the safe limit. Your 550's are good until about 330rwhp so you cant get all of it there. If you get a large turbo and can produce 330rwhp at 15psi, then your pump should just about be maxing out at the same time as your injectors.
 

·
Registered
Joined
·
5,228 Posts
93smgturbo said:
You can but its not safe. If you wanted to get all of the 550's use and use the stock pump you will need to bump up the base fuel pressure a few psi. Use this as a guide:

http://www.mr2oc.com/showthread.php?t=31686&highlight=fuel+pump

Basically you take your base fuel pressure of approx. 40psi and if you are running 20psi of boost, you look at 60psi. At 60psi that graph will tell you if your pump can keep up or not at those HP levels. It shows at 60psi that 300rwhp is the safe limit. Your 550's are good until about 330rwhp so you cant get all of it there. If you get a large turbo and can produce 330rwhp at 15psi, then your pump should just about be maxing out at the same time as your injectors.
Just a question. I thought that PSI wasnt "absolute"? Meaning that a large turbo running 15 PSI can make just as much power as a smaller turbo at 20 PSI, right? So even if the actual "PSI" is less, wouldnt there still be the same amount of flow from the turbo to make the same power? So then the pump wuldnt necessarily work better with a large turbo at 15 PSI making 330 RWHP than with a smaller turbo running 20 PSI, right? I may be wrong on confused so please elaborate.

Also, another question. How are all the different "turbo terms" "relative" to eachother? Like, if 15 PSI on a small doesnt necessarily have the same flow as 15 PSI on a larger turbo, then what is PSI relative to? Is it like at a given RPM (turbo RPM, not engine RPM), a turbo will produce the same "PSI", but they dont all actually flow the same? Ahhh Im confused lol. ANd sorry if what I wrote was confusing.
 

·
Registered
Joined
·
5,392 Posts
PSI is pressure, not airflow. Bigger turbo's flow more air at lower rpm's because they are more efficient. Your FPR has a neat thing where it raises the fuel pressure 1psi for each psi of boost you produce. So if you run 15psi on the ct26, then your fuel pressure will be(lets say stock is 40) 55psi. You can produce maybe 230rwhp at 15psi. Now slap on a TD06 at 15psi and your fuel pressure will still be 55psi in the higher rpm's when you are boosting. Yet you are now able to produce 280rwhp. Remember psi is pressure, not airflow.
 

·
Registered
Joined
·
467 Posts
Dumb question but its been awhile since I've been on the board. What do you need to run 550's on the stock ecu - FPR, AFC?

Thanks Gregg
 

·
Registered
Joined
·
467 Posts
Sorry guys I'm having someone do this for me and I will have the image down to size soon.
You all like my 2?
 

·
Registered
Joined
·
5,392 Posts
Nice duece, it looks to be in great shape. Are those 5zigen rims? They look nice. To run 550's on the stock ECU you will need one of these options.
1. EMS
2. VPC w/550 chip
3. S-AFC w/ AFPR(set the base pressure lower and add back in fuel, hopefully)
 

·
Premium Member
Joined
·
3,646 Posts
Wolfcatz. So stock pump with 550's and EMS isn't good enough for a ct20b at around 17 psi?


my setup is ct20b, 2.5" dp, greddy pex. stock pump, stock FPR, ats rail or wolfcatz rail, SDR ems, HKS IC. 17 psi at MOST.
 

·
Registered
Joined
·
467 Posts
93smgturbo said:
Nice duece, it looks to be in great shape. Are those 5zigen rims? They look nice. To run 550's on the stock ECU you will need one of these options.
1. EMS
2. VPC w/550 chip
3. S-AFC w/ AFPR(set the base pressure lower and add back in fuel, hopefully)
Thanks and yes those are JDM 5Zigens. Thanks for the 550 answers also.

Gregg
 

·
Registered
Joined
·
2,641 Posts
ek9max said:
Wolfcatz. So stock pump with 550's and EMS isn't good enough for a ct20b at around 17 psi?


my setup is ct20b, 2.5" dp, greddy pex. stock pump, stock FPR, ats rail or wolfcatz rail, SDR ems, HKS IC. 17 psi at MOST.

From my testing, if you have a stock fuel pump and 550's with the 550's held wide open (maxed out) then the stock fuel pump cannot keep up. Durring these test conditions, the stock pump loses the ability to build pressure with boost (for the fuel pressure to "rise") at 10 psi of boost. So at 17 psi of boost, your pump would actually be unable to raise the fuel pressure to the required 57 psi. It would still be at 50 psi. Thus the actual fuel pressure at the injector tip (fuel pressure - boost pressure) would be 50-17 = 33 psi. Thus, your injectors are moving less fuel than they would be at 10 psi of boost (50-10 = 40psi).

Now whether or not your car is using most of the avialable injector pulse width (injectors maxed out), is dependent on the setup or state of tune. If it were my car, I would not run a very large turbo without upgrading the pump.

Hope that helps,
 

·
Premium Member
Joined
·
3,646 Posts
WolfKatz said:
From my testing, if you have a stock fuel pump and 550's with the 550's held wide open (maxed out) then the stock fuel pump cannot keep up. Durring these test conditions, the stock pump loses the ability to build pressure with boost (for the fuel pressure to "rise") at 10 psi of boost. So at 17 psi of boost, your pump would actually be unable to raise the fuel pressure to the required 57 psi. It would still be at 50 psi. Thus the actual fuel pressure at the injector tip (fuel pressure - boost pressure) would be 50-17 = 33 psi. Thus, your injectors are moving less fuel than they would be at 10 psi of boost (50-10 = 40psi).

Now whether or not your car is using most of the avialable injector pulse width (injectors maxed out), is dependent on the setup or state of tune. If it were my car, I would not run a very large turbo without upgrading the pump.

Hope that helps,


So on a Ct20b, woudl I be better off with running stock injectors? I have EMS.
 

·
Registered
Joined
·
5,392 Posts
If you already have an EMS, you might as well put in the 550's. That way you can more safely turn up the boost. Those injectors are so cheap, its worth having that extra insurance and HP capabilites for $150 since you already have the EMS.
 

·
Registered
Joined
·
2,230 Posts
Hmmm... Am I on the verge of blowing my engine?

I have a ct20b that I run at 1.2 bar often (which I believe is a little over 17.5psi) on 91 octane fuel with a stock ECU, stock pump, and 440's. I do have WI for safety but I'm pretty sure I have hit 1.2 bar without it before.

Won't matter as long as this all lasts until tomorrow when I do some upgrades. :)
 

·
Registered
Joined
·
676 Posts
bubblebutt said:
Hmmm... Am I on the verge of blowing my engine?

I have a ct20b that I run at 1.2 bar often (which I believe is a little over 17.5psi) on 91 octane fuel with a stock ECU, stock pump, and 440's. I do have WI for safety but I'm pretty sure I have hit 1.2 bar without it before.

Won't matter as long as this all lasts until tomorrow when I do some upgrades. :)
Easiest way to check without being bombarded with 'you need this product!' is to put it on a dyno with wideband and check a/fs. You dont really wanna go over 12:1 on pump gas. On racegas you can push it a bit further, maybe to 12.3:1.
 
1 - 19 of 19 Posts
Top