Installed EBL on my 82 Corvette back in March. Rebuilt CFI with Renegade, Voodoo cam (112 lsa, 213/219 @.050, .484/.499 lift w/ 1.6 rockers) Dart SHP heads, 72cc chambers 200 cc runners, Forged flat top pistons, 9.5:1 compression, .045 quench. Lots of VE learns have my fueling solid, I haven't done much of the high speed tables yet, still learning stuff. I'm stumped on how to get the surge out of my idle. Attached are a data log and my latest attempt at editing the .bin to eliminate it. The data log was taken with this .bin active. Any help would be greatly appreciated!

Forgot to include: Stock injectors, 13.5 psi stable

 

Trying to idle at too low of a RPM. I'd go for a 750 RPM warm idle idle speed. Open both idle speed tables and add 225 RPM to all entries:

IAC - Idle Speed: Drive
IAC - Idle Speed: Park/Neut

Then see how it is. May need some additional tweaks but is a good start.

RBob.

 

That solidified the idle, thank you Did you notice anything else that I need to change?

 

May want to raise the stall saver RPM values by the same amount. Other then that would need to see if there are issues with how the engine now runs.

RBob.

 

No issues that I can see/hear/feel. The only issues I was having was the idle surge. Good smooth power and operation everywhere else so far. I haven't started working on AE or anything else yet. Take a look at my Low Speed VE table and see what you think. It has a weird spike at 55 kpa/2000 rpm. Goes up to 80.78 then drops to 68.24 at 65 kpa/2000 rpm. I had that area smoothed and a VE learn set those values. Other than that, the graph is pretty smooth. Knock count on that run was 8, forget where in the rpm/kpa range though, I'm thinking right around the same area. No counts there since, though, so I haven't messed with it.

 

My set up is similar- Renegade & CFI.

I've taken my TBs out to 49.5mm and I'm running a .465/.488 cam on 1.5 rockers with 9:1 CR. I needed larger injectors, 85 fuel pump, 20 psi, and then a VAFPR to get the fueling worked out with VE and injector duty cycle to get it to run well.

I also added a wideband for tuning- and that's helped too. Not sure if you have one, but they really do make a world of a difference and the tuning is a lot easier with one as the reference point for AFR.

I'm still working on a few things here and there... but it's been a lot of fun and a great learning experience

Your cam should be up to 5,500rpm for it's range, according to Lunati. If you have the OEM governor, a 700R4, and the OE gear ratio in the back... what RPM does your shift from the 1-2 happen?

I bring this up because mine shifted at 5k until I reprogrammed the governor. I needed to swap springs out to get mine to shift out of first at 5,400 (~ B&M purple and B&M orange springs) and from 2-3 at 5k rpm. Max HP for me is around 5,300rpm and I wanted to get just on the other side of it before I left 1st gear.

And with more rpm... I needed more fuel, more fuel pressure, and more duty cycle.

Just food for thought...

 

In the process of moving to 3.54:1 rear gears, currently the stock 2.87:1 now. Shift points are stock, haven't done any WOT runs yet, still working on low speed VE. I'm looking at the 454 injectors. You said you went to VAFPR, did you parallel plumb? How did you set that up if you didn't go parallel? I can stay with my current injectors if I wanted to really push the pressure up, I do have a TPI pump installed. I'm not convinced the stock pods could handle upwards of 30 psi though, so I'm looking at 80-90 lb injectors. Pulse width at low rpm and idle concerns me with that large an injector. Also, getting the TBs bored and retaining the balance ports is a concern. I do have a spare set that I will be bushing soon, if there is anyone out there still boring them out, I'd like to find them. Keeping the balance ports functional is a deal breaker, though. I'm not racing the car or burning up the asphalt light to light, I just want really good drivability with power available when needed.

 

That was EXACTLY what I was going for as well.

I'm going to move up to a 3.55 rear end next summer- and perhaps 1.6 rockers too.

With the Renegade intake, I have been able to get up to 95-96 KPAs (out of 98 KPAs possible) on WOT at 5,400rpm with stock air box, headers, etc. on 49.5mm TBs. So, I guess the set up flows decent. I've been pretty happy with it as the acceleration is pretty good.

I went with Maxbore to bore the TBs. I too wanted to keep the balance ports- sounds like you and I are working on similar cars.

I didn't go parallel because for me... keeping an almost dead-stock appearance is important.

I want to keep the sleeper look. Since I'm not running down the drag strip, I guess it's okay to have slightly different pressures between the pods.

From what a bunch of guys here have found (like Grumpy & Dom)... is the higher the fuel pressure and the larger the injector, the more noticeable the differences are between TBs when running in a series. Running parallel removes that problem. I'm not sure how noticeable it is at lower pressures with larger injectors- so maybe Dominic would chime in based upon his convos with Grumpy in the past.

I have a modified GM marine application pressure regulator where the relief port is being used as a vacuum port. It was a pretty common mod a few years ago, but it's seen less often as the parts are now discontinued.

 

"From what a bunch of guys here have found (like Grumpy & Dom)... is the higher the fuel pressure and the larger the injector, the more noticeable the differences are between TBs when running in a series. Running parallel removes that problem. I'm not sure how noticeable it is at lower pressures with larger injectors- so maybe Dominic would chime in based upon his convos with Grumpy in the past.

I have a modified GM marine application pressure regulator where the relief port is being used as a vacuum port. It was a pretty common mod a few years ago, but it's seen less often as the parts are now discontinued."

Using the BSFC calculation for determining fuel required at a desired power level, let's look at the stock injectors.
IIRC, the (63.5 + 65)/.5#/hp = 257hp at 100%DC or 218hp@.85DC.
Now this is at the FP used to rate the injectors, which again IIRC was 13psi. My Xfire was putting down 284rwhp. So you can bump the FP to have the stock injectors provide enough flow at WOT. Not sure what that would be but w higher FP, the differential between the 2 injectors is magnified. I once measured the pressure drop between the 2 TBIs and it was about .5# front to rear which is why the rear injector was somewhat larger. Tuning for idle and low rpm cruise was problematic. I was using a 7747 at the time. EBL came out and included support for a VAFPR and variable FP. BINGO!
Now I could use larger 80# injectors with a WOT FP of 20# but drop down to 10psi for idle.
Since there were no larger injectors available that could replicate the flow differential of the stock injectors, I needed to use the same injector in both TBIs, which then requires the same FP at both TB. Ergo, // plumbing. My TBs were bored to 53.25mm. Basically my cam was more aggressive than what I see here, with a tighter LSA, more lift and duration. But it still idled nicely at 800rpm. The cam was very close to the LPE cam for the TPI motors. I think I could have gotten more out of it with a less restrictive exhaust(still using a Y-pipe into a single Random Tech cat) and 2.25" pipe w LPE headers. Best ET was a 13.37 w a 2.0 60'. My best trap was 104.5mph, all on street tires and 3.45s in a Dana 44 behind a ZF-6.
Also installed a Fidanza FW using a Camaro clutch disc.
So bottom line is the stock injectors weren't going to cut it and there really isn't any alternative to using larger injectors. I took my car to the dyno before EBL and no matter what I did to the VE table, my AFR wouldn't drop. That's when I realized injectors were going static.
One other thing, you need to know how much injector you need for WOT before tuning part throttle. Or you end up like me having a nice driveability tune, then finding out you need more injector for WOT.

 

Yes, I've done tons of BSFC calcs. With the stock injectors, I'd need upwards of 30 psi at WOT to get it even close to the fuel needed. I don't trust the stock injector pods at that pressure, I think I'd end up with a pair of fountains in short order. I'd love to see how you plumbed your injectors. This is on my to do list. Thanks for that post, it points me in the right direction and confirms what I already thought.

 

What I'd really like to find is offset data on the stock and the TJ11 injectors. I think that would help tremendously. All my searches have come up empty thus far.

 

Ok, here's a few pics of how I // plumbed and of the car before I sold it. I'll be the first to tell you "Don't do it this way". There are much cleaner examples of how to do it using hard lines.
I've also included a zip file that has one of my last EBL bin cals for the car. Doubtful it will work for yours but it will give you some ideas. I'm hoping it still works w the EBL .xdf. Its from 2006.

 

Thanks, it gives me a place to start. I've already started designing a block off plate and I'll be able (I think) to fab up something for the fuel lines. How much pressure do you think the stock pods and injectors can handle with good block off plates? I've heard higher pressure with smaller injectors is better than larger injectors with lower pressure. I have two sets of stock injectors so I could use two 65# injectors // plumbed at higher pressure (I have an 86 Vette TPI pump installed now). Either way works, 30psi w/ 65# injectors should support up to 373 hp @ 85% duty cycle and I think my combo is capable of about 350 at the flywheel. I can give specs of the build if you like for estimation purposes.

 

Well, higher pressure should give you better atomization, but I'm not sure that is too applicable to TBI. Remember the fuel is being sprayed against the TB wall and then sheared off by the incoming air. Besides, the stock injectors are running at pressures way above their rated pressure. Finally, your time at WOT is minimal in comparison to part throttle and idle. I would opt for reliability and minimizing the stress on components. 20# for max pressure on an 80# injector worked fine. I was able to bloc off the TBs using rubber gasketing material and thin aluminum sheet at that pressure. Also was using LT-1 pump.

 

That sounds reasonable. Thanks for letting me pick your brain on this.

 

Dom- thanks for jumping in. I was pretty sure I was going to butcher what you and I had talked about in another thread. I get the concepts- just not the best at explaining them. So... thanks!

FWIW... I'm running TJ11 injectors. They are supposed to be 90# from what I understand.

I started out running 16 psi based upon the BPC calculation and thought it would be enough. My set up- cam & heads- is capable of around 325 at the flywheel.

I ran out of VE and injector... so I raised the pressure. Yes, I was using higher flowing fuel pump and then had 20 psi on the gauge between the front and rear TBs.

I still didn't have enough injector (DC).

I then went to VAFPR.


That was what I needed... 20 psi and a VAFPR.

 

I'm looking at the Aeromotive 13301 regulator and redoing the hard lines along with limited use of braided lines and some block off plates to move to TJ11's and parallel plumbing. I'm in the planning stages now. All my extra funds went into the diff rebuild so it's gonna be a few months, but I'll get there. Meanwhile I have excellent drivability with my current set up so I don't mind waiting a little while to start, plus that gives me time to plan out how I want to do the project.

 

The Aeromotive is a popular VAFPR. I used it for years and it was very reliable.

 

Damn that LT5 looks sweet

 

It runs even better than it looks. Amazingly, what I learned tuning the Xfire was directly applicable to the LT-5 thx to RBob, Grumpy, Traxion and others. Both are SD motors.