400FWHP TBI build attempt thread

**Gojira94** · 12-17-2016

Well, the line breaks didn't make it into the post. replaced with screenshot.

**Gojira94** · 12-17-2016

Here are the VE tables I came up with as a starting point. I used a calculator to generate some fairly sparse data points and then filled in and shaped them in TunerPro. They may be total crap, I'm not sure. The transition from low to high is smooth and the highest VE is in the area where the engine should make the most torque efficiently.

**Gojira94** · 12-20-2016

I'm needing some guidance with what to input for BPC calculation in EBL Flash. I originally calculated using the TBI Fueling page at dynamicefi.com before getting started. I reckoned a hair under the example used on the site and came up with 80# injectors at 22-23psi, 85% duty cycle. I realize that's the point at which it would need max fuel for theoretical max HP at 5500-5700RPM and not where the engine will be running 95% of the time. I talked to Sean at SPR when I ordered the TBI, told him my mods/ goals/ expected HP needed to support, that I'd be using an Aeromotive 13301 VRFPR and would need a blockoff plate. He said BBC injectors are not the way to go, just dial up the pressure on the 60.5# injectors. Using the BPC calculator, I get 39psi needed to support that peak HP with 60.5#s. This seems like an easy place to completely blow the tune if BPC is wrong from pressure and flow rates way off. So my questions are 1) How much pressure can the 5235206 injectors handle? 2) If they can handle 39psi, I'm wondering where to set the base pressure on the regulator with the 20-65# spring? 3) Would a minimum of 20# be too much and I should be looking for a spring more like 15-45psi that fits the 13301? Thanks

**Gojira94** · 12-22-2016

I think I've answered my own questions about the pressure. 39-40psi will be ok, EBL's BPC tables will handle it. Base pressure on the 20-60# spring needs to be set at 39-40psi with the vacuum nipple open to air. Then connect it and let vacuum handle the pressure drop at idle, with corresponding BPC vs. VAC table values. I expect a touch over 15" Hg at commanded idle speeds with IAC vs. temp at normal operating temps. Next question is why am I missing the BST-BPC vs Boost for a 1-bar MAP?? I see 4 tables each for 2-bar and 3-bar but none for 1-bar. I looked in the option words and as expected none of the 2 or 3-bar words are set, and apparently I didn't miss turning on the default of 1-bar MAP. So, if using a 1-bar MAP, just don't worry about the BST-BPC vs Boost? I think this is pretty much the last thing for the base starter tune. Again, any feedback or criticism of anything I've posted so far with any of this is appreciated.

**Fast355** · 12-23-2016

Personally I wpuld run the big block injectors at that power level. I have run the 61s as high as 50 psi but the opening and closing times start to get too long for higher rpm use.

**Gojira94** · 12-24-2016

Originally Posted by Fast355

Personally I wpuld run the big block injectors at that power level. I have run the 61s as high as 50 psi but the opening and closing times start to get too long for higher rpm use.

Thanks for the input. When you say higher RPMs, how high? I'm planning to spin no higher than 5500, limiter set at 5750. I'm feeling like I should have insisted on BBC injectors. I think I'd have fewer concerns and questions.

**Fast355** · 12-25-2016

Originally Posted by Gojira94

Thanks for the input. When you say higher RPMs, how high? I'm planning to spin no higher than 5500, limiter set at 5750. I'm feeling like I should have insisted on BBC injectors. I think I'd have fewer concerns and questions.

You are going to have a hard time making 400 hp under 6,000 rpm on a 350 that mild.Pulsewidth to stay under 80% duty cycle goes from 5msec at 5,000 to 4 msec at 6,000. If it takes 500 usec to open the injector and another 250 usec to close you are looking at needing an injector that can get the fuel volume necessary in 3.25 msec. Big injectors are a must for a high hp TBI.