however, the price of a FP or walbro is so cheap that its good insurance anyways

 

Well that is going to be my next mod since the IDC is at 98%.

 

Personally i don't like IDC's that high but i have run 90+ on other cars for years and not had problems.

While we're talking about it what IDC do the injectors go static on these cars?

IF you're at 98% duty cycle and it's still lean then i would start with a pump AND more fuel pressure for sure. Larger injectors would go a long way toward safety.

 

He is a log that I did today, running 3rd and 4th gear. I am at 25psi peak holding 22psi to redline. Mods are in signature. I am seeing IDC of 101%, what do you guys think!

To view file just saved it and remove the .txt extencion.

 

yes definatley need a FP upgrade.

do that first (coz you will have to anyways)

then retune your AFR's and recheck your IDC, it should drop by 5% maybe... if it dosen't then consider getting bigger injectors too.. Not good to be running around at 100%

 

Whys does the pump need replacement?

Will IDC go down with pump replacement?

Shouldn't the Injectors be replaced instead since it is the one that is maxed?

 

Evo 8's are known the have dodgey fuel pumps - adding a walbro will push more fuel through the injectors thus requiring less IDC.

as I said, since he _needs_ todo the FP anyways he might as well see what his IDC's are after b4 doing injectors...

 

I know I have posted this graph from AMS' tests in several other threads, but it's a good one, so one more time won't hurt. It shows how the Evo VIII pump drops off in flow:

 

Looking at that graph, why doesn't twin internal pumps push twice as much fuel as one, since the external pumps will do that? Is there some limiting part int the fuel line near intank pumps?

 

So power wise, how much horse power can the stock fuel pump handle? I only have TBE and intake with flter, basically the boost went up by just adding those things, I could turn the boost down a little until I get the fuel pump.

 

Well not quiet what your asking for but ....
Stock IX fuel pump was fine for me @ 355WHP @ 11.3's A/F @ 100-110 IDC
Now its cold out and the IDC are over 120 A/F went over 12.0 uptop .
So I had to drop boost 2 psi,add fuel and drop 2* of timing just to stay out of knock .
Ix pumps > VIII pumps and I just have Intake, 3"TB,IC@25psi .
I hope Santa brings me a FP b/c iam in need .

 

Well I just ordered a walbro fuel pump today, hope to install it as soon as it gets to me. One thing to note is that I ran 12.0 AFR uptop and I saw no knock, right now I am running 11.1 ARF at 6000rpm to 7000rpm, can I add more timing, I have not mess too much with the timing tables.

 

So is it always the pump that is maxed out first before the injectors?

I have IX w/ TBE, mbc, and Walbro FP and still see 90-95% IDC on 11.4-11.5 afr up top.

Sorry to hijack your thread pupo.

 

Well, like tephra said on a few post backs, by adding a fuel pump you get extra pressure wich make the injectors flow more fuel, but you still need bigger injectors, the fuel pump will help get lower IDC. In my case I think that just upgrading the fuel pump will help me achive what I want and that is to not run at 100% IDC. Eventually as I keep upgrading thinks I will need bigger injectors.

 

The stock injectors can flow enough to support a maxed out stock turbo. The stock IX pump, based on AMS' test above can as well. What we don't have are the numbers at something more realistic, like 12V. The voltage at the pump is the real factor there.


Eric