Wanted to document this as we go, as the development of a starter bin to be used with the EBL Flash system was recently initiated. First things first, very little information is known about this particular engine with respect to its' stock tuning specifications. Did not come across any stock Bin's out there to use as a reference in relation with, well, anything. Meaning, ask ten different L83 owners what size injectors this engine came with, and you'll get ten different answers. There does seem to be an early chip that was released by Hypertech, but you would have better luck stumbling across a 1943 copper penny as opposed to cross referencing any of its' information. So we're starting from scratch, albeit with some help from the LO3 and LO5 bins which both share its' two fuel injector fueling system. Now, when we first started, I was told that the injectors came staggered from GM, meaning one flows more than another. Other than the part numbers of the injectors themselves, in which I did come across, I cannot verify what that fuel flow rating is at 13-psi of fuel pressure, and nobody seems to know for sure. So since we are tuning the VE ourselves anyway based on AFR, the injector flow information, though helpful, isn't really needed. It's just annoying that the BPC will not be 100% perfect, though will in fact be close. How? Well, let's base our fuel flow information on how GM selects injectors, usually by horsepower and a cap of 80% duty cycle. So, if say a stock 305 and 350 Tuned Port Injection came from the factory with anywhere between 220 and 250 flywheel horsepower, and a stock 350 LT1 came from the factory with 300 flywheel horsepower, then;

8- 18# Injectors @ 0.50 BSFC @ 80% Duty Cycle is good for about 230 Horsepower...
8 - 20# Injectors @ 0.50 BSFC @ 80% Duty Cycle is good for about 250 Horsepower..
8 - 23# injectors @ 0.50 BSFC @ 80% Duty Cycle is good for about 300 Horsepower..

So with a staggered two injector system for the L83, we do know that these engines came from the factory with about 200 Horsepower, and GM more than likely used 80% as its' cap like it always did. The fuel flow in the tune was also more than likely averaged, being that both injectors are forced to share the same VE table. So;

2 - 62.5 Injectors @ 0.50 BSFC @ 80% Duty Cycle is good for about 200 Horsepower...

Again, we don't know the fuel flow rating at 13-psi for those two L83 injectors, we only know that they were staggered. Anything else is just a guess. So if we average them out, and if we base the injector size on what was readily available through GM, we'll have one injector at about 61#, and the other at about 65#, giving us our 62.5# average for 200 flywheel horsepower. Close enough as far as I'm concerned, so with using 62.5 at 13-psi in the WUD utility, the BPC is 133. Be sure to leave the Vacuum Reference button unchecked because the L83 did not use any...

So now we move onto spark advance. All L83 owners agree, Base/Initial timing is 6* BTDC. Nobody seems to know SA Idle State for the L83 though, so we'll try basing that on what we find on the LO3/LO5 setup, between 15* to 20*. I mean' we're talking about a 200 horsepower engine here. But just for sake of performance, let's start with 22* at idle for the L83. The other parameters, like the IAC settings, Cold AFR, beginning VE table etc, will be based on the LO3/LO5 as well, mainly because they share the same size injector flow from the factory, not to mention being that we have nothing else to go with. Should be close either way. Though I will point out that the Main Spark Table was smoothed out to compensate for the 22* idle state in the lower RPM area. The VE we will dial in as we watch the INT/BLM, as we also have no wideband feedback to go by with the test engine(s) who have volunteered for this, so we'll be tuning old school for now, just to get it up and running.

Okay, so with the Bin being based on a 133 BPC, 6* Base/Initial, 22* Idle State, and LO3 VE table, the first Crossfire L83 engine fired right up and idled. However, the engine was running rough at idle. First thing noticed was the BLM, it was pegged at 108. Though the INT tried its'; best, the fueling was just way too rich. the BLM remained at 108 throughout. Pulled fuel repeatedly to dial it in, and after all was said and done, and after about 30% of fuel being taken out, the BLM was finally at 120-BLM. Tad more fuel was pulled, and it settled closer to 128. However, the roughness remained. Despite the roughness, started to dial in some of the other areas to give the engine a little more kick off idle, part throttle and wide open throttle. Owner liked the additional power over the stock setup, but the roughness remained. Hmm. INT/BLM is rock solid, idle RPM is averaging right where its' being commanded. Rough? Fouled spark plugs? Arcing wires? Let's start the process of elimination. Up until this point, we were just testing on one L83 engine. Took the same tune and applied it to another stock L83 engine, that engine showed to be lean so 6% more fuel was added. That was kind of strange though, as both are stock, first was tuned to stoich, yet second needed 6% more fuel. Chalk it up to every engine being different, or maybe one had an open element air filter. Anyway, though the second owner also loved the increase in performance, he too had stated the engine was running rough at idle. When both were asked to clarify more, roughness is down low at idle and off idle, 700-RPM t0 1000-RPM.

Hmm. Both datalogs are showing 17-18" of vacuum at idle, kPa at around 45 or so. Fuel flow must be close, it would have to be, and even if it weren't, the INT/BLM trims are exactly where they need to be. Should be running smooth. Now I am thinking Injector offsets, and Spark Latency. Again, nothing is known with the L83 other than being a problem child for most owners for some reason. Looked at the Injector Offsets for the LO3, immediately noticed that the first two values (0 to 1.6 volts) were halved from the 3.2 through 6.4 range. Seems common with the TBI engines when looking at the other Bins, but this is trial and error, lets see what happens through experimentation. Common practice with port injection is to raise the 0 to 1.6 volts to match the 3.2 through 6.4 volt range. So we tried that. Engine had trouble starting, and was very flat off idle. Okay, so we'll go the other way, let's zero them out. Not only did we zero those two injector offset values out, but we also lowered the Idle State from 22* down to 18*....

That is where we are at the moment. Will have feedback today from both test cars. So far, both engines have excellent power, one enjoys chirping the tires on both first, second and third gear in an automatic. But it's the roughness at idle and off idle that is the setback at this point. Now, I was just told there was someone in my area that would also like to be used as a test subject, so tuning the engine in person will make one hell of a difference, which should take minutes at this point, especially with the Bin almost being wrapped already, save for the roughness issue. Will continue to add to this thread as the Crossfire Bin is finalized. More and more L83 owners are going EBL, so a solid starting point will, at the very least, help them out...

More soon.

- Rob

 

Thanks Rob for starting this thread and an excellent post about this journey so far. It has been interesting to say the least and I sincerely appreciate the cooperation from you and the three 82 corvette owners that are using their stock CFI corvettes as test mules on this project. Since they all are using the EBL, it will only benefit anyone with a 82/84 corvette when their stock ECM dies and they go this route with the EBL. The only reason we are doing this is because there is nothing out there at the moment to help the CF corvette guys as far as a tune goes. I'm excited to hear that you may be able to physically get hands on tuning on a 82 locally, what a huge benefit that should be in all this. I say the performance gain will be very nice as evidenced by one of the owners so far, much better than stock. Don't know about mpg though, but it's a corvette, so who cares, right?

 

Update; feedback received from the two test vehicles above. But before we get into that, need to clarify the differences in the tuning. The Injector fuel flow was always questionable with this particular engine. I was satisfied with the 61#/65# combination (which averaged 62.5#), but just as a fail safe, we also started with the fuel flow of 67# on one of the two as an average to see how it would respond with the change in injector dwell;

First test engine with the 67# BPC @ 13-psi of fuel pressure; we initially tested this engine with the stock dwell setting with the first two (lower) values being halved from the ones that came after up until 6 volts, The engine ran rough at idle from the getgo, though started up from cold well. We then doubled the first two values, with the engine immediately having trouble starting and feeling flat off idle. We then zeroed out the first two values and reduced the idle state to 18*, and the engine was still rough. Remember, this is starting with a 67# BPC.

Second test engine with 62.5# BPC @ 13-psi of fuel pressure, we initially started with the same two values in the offsets using the stock setting, halved. Engine was the same, rough down low, though did start up okay when cold. We then doubled those two values to match the values that came after up until 6 volts, and the same thing happened, engine had trouble starting, and was very flat off idle. We then zeroed out those two values and reduced the idle state to 18*, and the owner immediately reported the engine being next to perfect. Started perfectly when cold, warm, hot, and had excellent power which made him grin from ear to ear (was happy to hear that). So in his case, we'll slowly raise the timing until raising it doesn't do anything anymore, then back it down a tad. Excellent.

Back to the first test engine... went back into the Bin, and changed his BPC from an average of 67# fuel flow to 62.5# as well as added 6% fuel back into the VE to compensate for that change. I already had given him the 18* idle state before hand, as well as zeroing out the first two values of the injector offsets, but the BPC was kept at 67# during his last test, which maintained that roughness. So now we are waiting for feedback with the change in his BPC to 62# which I gave test engine two, which will hopefully sort his roughness out. Being that both engines are stock, it should do just that. If it doesn't, then it has to be something mechanical which we'll look for after his feedback, like arcing plug wires, plugs themselves, as well as checking that his base timing really is set to 6* BTDC, and not skewed...

So that is where we are now. Test engine one is pending feedback with the 62.5# BPC, and test engine two is completed. Will be working on test engine three in person some time this week, and will of course be initially starting with test bin number two since we know it is wrapped up.... though I just gave test engine two more timing, and I'd like to get some feedback from that change as well. But the main issue here now, is that test engine one gives us feedback sometime today after testing with the BPC set to 62.5# from 67#. Will update this thread as soon as I hear from him, and if he has great feedback to report, then this Crossfire Bin should be considered a wrap....

More soon...

- Rob

 

Update; we last left off waiting on two datalogs with both test engines running the same exact BPC, VE Table, as well as timing. Test engine one is the one we were anticipating because of the roughness issue. Latency was changed on both engines because of test engine's one's roughness even though test engine two didn't need that change. With the Latency changes, the results were about a 5* timing pull for both, so they experienced hard starting, and dipping of idle. That's actually good news, as they are both on target, so the Latency will be restored to previous values to correct that. However, test engine one's O2mv's were pegged low at wide open throttle (see below comparison), whereas test engine two was right where it needed to be. The VE is still being tuned for off idle which is why both are showing a richer BLM during PE, but our main concern was diagnosing test engine's one's roughness issue. So now we know we're dealing with a fuel pressure issue for test engine one. Also, they are not running a wideband so ignore the wideband AFR. Owner indicated that he is running a new fuel pump, and that he confirmed 13-psi at idle, but had not tested pressure off idle and with a load yet, but he doesn't need to at this point. as the datalog underlined the low of pressure issue. So as we finalize the Bin, test engine one's owner will look for that fuel pressure issue. Latency was returned to its' previous values as of this writing, and new Bin will be sent to the owners tonight. Tomorrow's datalogs will confirm the return of the quick startup, and solid idle, with the Latency change, Am also tuning the third test engine tomorrow in person using this Bin to dial in part throttle VE, and then we'll call it a wrap for all three...

- Rob

 

Update; Forging ahead... we recently learned that test engine one (the one with the roughness) is running replacement injectors from an '84 L83 in his '82 L83. Normally this should not be an issue, as the ECM's are interchangeable between those years, and the injectors should be the same size. However, the Injector Constants may very well be different. Owner sent me what appeared to be a part number off of both injectors, staggered of course, front and back, but the part numbers are not searchable. The only thing I came across was an old ebay auction which listed one of those part numbers exclusively for an '84 Corvette. Luckily the owner still has his factory '82 injectors, and we are waiting for him to reinstall them to at least confirm that the roughness has subsided. Wanted to take a peek at the stock '84 L83 Bin file while waiting, but can't seem to find one, so we'll wait for the owner's feedback after he reinstalls the stockers to see if they did the trick...

Test engine two is extremely happy with the latest Bin sent to him with the increased timing. Just sent him another Bin file today with a tad more timing, so we'll see if the engine likes more, have a feeling it will. So that test engine is a wrap...

Test engine three I visited today. One very pretty C3 Corvette, let me tell ya. I flashed in the most current tune for all three, and despite all three engines being essentially stock, test engine three needed 10% more fuel added into the VE. Also gave him just as much timing as test engine two's latest Bin file, but we have very bad weather here today, so his road test will be delayed. But idle, and off idle, are dead on. So test engine three is pretty much a wrap, pending final road test...

So we're only waiting on test engine one, need to confirm the stock injectors did the trick...

- Rob

 

VERY nice 82 and GREAT posts Rob. Also want to thank Ray for his cooperation in all this and coordinating the use of Lloyds 82 in this project. Rob did an OUTSTANDING job on the tune for this car and the entire tuning process for the other two 82s involved. I was hugely impressed with his work! I'm dying to start my new tune with my 82 and "catapult" it into the 11s. Thank you again guys, you were amazing.

 

You are more than welcome Tom. Everyone who participated made it extremely easy to remote tune, as the feedback I was receiving was perfect, as were the datalogs. Huge credit must go out to Bob Rauscher for creating a system that is so compatible with the Throttle Body Injected OBD1 based engines, and I am extremely glad that the Crossfire Engines have since joined the EBL family. From what I understand, there were in fact some CFI engines out there that have been utilizing the EBL before starting on this, am hoping that what we were able to accomplish will make it that much easier for others to jump onboard now having a strong base tune to start from as well additional power enhancements to make their cars more enjoyable, while maximizing their Crossfire setups. Am also confident we'll be getting your personal Crossfire engine into the 11's when you're back in the saddle with it, but that is for another thread. We'll call this thread a wrap...

Crossfire L83 Tune Complete and initially based on;

6* Base Timing
20* Idle State Timing
Custom Main Spark Table
VE/BPC = 62.5# @ 13-psi
Tuning enhanced off idle, part throttle and wide open throttle
Highway AFR kept in tact
Closed Loop based

For the Crossfire L83 who are starting with different sized injectors and fuel pressure, as well as engine size, and this includes the LU5 guys and gals starting with the 305 Crossfire engine, you would only need to change your BPC to equate to your current engine size and fuel flow, which is easily doable using the WUD utility provided with the system. From their, either trim down, or add to all three VE tables when you calculate the difference in fueling. Eg; if you're running 80# injectors at 20-psi of fuel pressure, the new flow rate would be 99#. After calculating that difference between 62.5# and 99# flow rate, adjust the three VE tables and you will be close. From there, just fine tune either through VE Learning, or manually adjusting and shaping the VE tables.

Bets of luck everyone, and enjoy...

- Rob

 

Just wanted to update this thread one more time in reference to test engine one. To reiterate, the owner has been running replacement injectors since we initially started, but had been complaining about running rough at idle, as well as a lack of power at part throttle and wide open throttle. Datalog showed he was losing fuel pressure at part throttle and wide open throttle, which was explained above. Asked the owner to reinstall the stock injectors as a test, which he did, and immediately he described the front stock injector coming to a halt after two to three seconds after startup. it simply stopped firing, whereas the rear stock injector kept firing. Asked him to check all four injectors with a voltmeter, and all four checked out okay. Then asked him to switch the stock injectors front and back to see if the front one still stopped spraying after two to three seconds again albeit using the rear one in its' place, that test is pending So it's possible we're looking at a connection issue...

I also sent RBob this Crossfire L83 Bin and asked him to host it for other L83 owners wanting to go with the EBL. Also, had a couple of members asking about the LU5, and if people are interested in a Bin made specifically for the LU5 as opposed to starting with the L83 Bin from above and having to change the fueling as well as other parameters to make it work for the Crossfire 305, then shoot me a PM. I would just need one or two stock LU5 engine owners to work with me, and to feed me datalogs. Just say the word, won't take too long at all to complete....

- Rob

 

This is a response to the finalized tune from one of the 82 test mule cars we used for the tuning process and a testimony to Rob's ability to tune CFI nicely! This IS so funny, but great! Thanks again Rob for doing this project.

Tom,
I reset the TPS and took it for a test drive. The doors starting turning into wings, had to back off!! More speed than a cruiser like me will need but nice to know its there. NO PROBLEMS OR ISSUES. BIN 5 IS GOOD TO GO!!

 

Very nice work! I reached out to Bob for the L83 tune to run in my 84' crossfire corvette. Works excellent! Good throttle response and very snappy.

I do have a question tho.. Were the test mule cars all automatics? I have a 4+3 and the engine is unsure on what to do when I push the clutch in and the car is still moving. Idles around 1200 rpm while coasting to a stop, but at a dead stop settles to 950-1000 rpm after about 15 seconds or so. Thoughts?

 

Excellent feedback! Yes, all three test cars were automatic. I am very glad you responded to this thread, as these are the areas that you will want to address for the manual versions;

* IAC - B9in Idle Speed (its currently set at 1000-RPM, but you can change it to either 800-RPM, 850-RPM or 900-RPM if you're modded). However, since your engine is hovering at 1200-RPM while coasting, and this Bin is pre-set for 1000-RPM while coasting, and since your about 950-RPM to 1000-RPM at idle once settled back down, with this Bin being pre-set for 725-RPM, it sounds like you're about 200-RPM higher than what is being commanded. Make sure your IAC steps and TPS are correctly set during idle RPM at operating temperature, you will want to see between 25-35 IAC steps at operating temperature in either Park or Neutral with no throttle being applied, and in between 0.5 to 0.8 TPS in the Diagnostic Screen...

* IAC - Idle Speed Drive & IAC - Idle Speed Park (this is optional, and also depending on your desired idle RPM. You can make these two tables match one another by either cutting and pasting the Drive scaler into Park, or vice versa). A manual will normally only use the IAC - Idle Speed Drive scaler, but its always best practice to keep the Bin as close and correct as possible for the specific engine in all fields, even if unused, so you can match them to keep them in sync...

- Rob

 

Yep, '82 Corvettes could only be had with the 700R4 transmission. Stick was not offered.
Finally had a chance to hop on here and give it a read. Rob's been an absolute blessing for us. I can tell you that other local shops are running into this same issue, as these cars get older, and the ECM's that you can manage to find are all trashed. IMO, this a really elegant solution compared to junking the whole system for a carb or aftermarket EFI. Look for an article in the NCRS Restorer in the coming months.

 

Ray, that is absolutely awesome news! Thank you....!!!!

- Rob

 

Yes it is Ray!... Rob modified that stock CFI bin that works great for the stock CFI for my 383. The new bin for my motor is a starter bin and going from there. I loaded it today and it fired right up with no issues and idled just nicely. I WILL be datalogging that tune soon, but the heat here in Arizona is brutal already. Ugh! I think like Ray and Rob, the EBL Flash IS the best solution for any CFI motor if your ECM goes south and Rob did an awesome job on the stock tune as well.

 

Flashed the tune on the 84 Crossfire Corvette MANUAL changed parameters as noted. All seems excellent! I would suggest a MPH throttle down for the manual transmission. I have not changed it in mine yet, but the throttle down is fine when the clutch is pushed in, but will not idle to SET RPM until you reach the 8-4mph zone. Am I wrong in this thinking?

Thanks for all the hard work!

 

Thanks Tom, you guys have been absolutely awesome, and made the whole process of getting it done a breeze. I'm looking very forward to working on a boosted CFI tune using the EBL Flash, just waiting on a volunteer....

Again, excellent feedback! The throttle follower decay rate can be tricky. Though the Bin is currently set to a VSS Low MPH Breakpoint of 12-mph, the decay rate in the lower filter (12.48%) is more than likely the culprit as to why it isn't fully being realized until 4-8 mph, it's lagging. I agree, this is an area that I would rather the user themselves determine as to where they would want the Breakpoint to begin, and how fast they would want that decay rate to reach commanded idle RPM when it does. 12-mph seems like a solid target, but you can up it to 15-mph to speed up the process. However the 12.48% coefficient is a tad on the slower side. Perhaps increase it closer to 25 to 30% in the Lower filter entry...

* IAC - TF Decay MPH
* IAC - TF Decay Filters

- Rob

 

Am very serious about this. All it takes is the fabrication of the intake to act as a carb hat. Can even make it resemble the stock one if need be, but one solid piece in which both throttle bodies share the same air inlet, would just need it to be a 2 1/2" or 3" round orifice. The universal Vortech system is ideal. Even a home built turbo system will work, and could be made for cheaper. Nothing too crazy, maybe 7 1/2 to 12 pounds of boost, which is safe. Could have a boost tune completed and wrapped for someone based off of this Bin, in fact I already did it lol. Would just need to work the VE in boost with a datalog, as well as install a vacuum referenced adjustable fuel pressure regulator, and of course, larger injectors. Just putting this out there in case anyone running a CFI wants boost...

- Rob

 

That's SO funny that you mention that Rob. I wanted to do that years ago and even started drawing a new airbox for that system using a Procharger. Lots of issues to work out, so I abandoned the project. Sounds like a cool idea though. I think that Joby on C4 CF and the old Crossfire Vault forum is the only one that I know of that did something like that on an 84 and ran pretty good. LOTS of fabrication to make it work though. I also have the complete list of parts needed for a NOS system for a CF that used to be manufactured for a CF. They stopped making that a long time ago, but the parts are still available. A guy did it to a bone stock 84 and it ran 11.70s on 125 hit.

 

Tom you should fabricate one, and offer it to the CFI guys. Seriously. Controlling the boost is the easy part; Injectors, 2-Bar MAP, and vacuum referenced regulator. I already did the tune. Would definitely like to see the CFI guys kicking butt at the track with boost....

- Rob

 

Joby documented this and has a great web site with a ton of information:

http://www.joby.se/corvette

Well worth the visit. Just an FYI, he is also the developer of WinALDL:

http://winaldl.joby.se/

RBob.

 

Thanks for posting that Bob. I forgot that Jonas still had that online. He was truly a pioneer back then on the boosted mods for CFI. He has been somewhat away from the forum scene, a hit and miss kind of thing over the years. I recently saw him posting again on the forum in the C4 forum. He also contacted me about the Renegade manifold and some ideas. At some point, maybe I will pursue that project again...and give Rob something to do. LOL

 

Was telling RBob that if I come across a 305 roller block that I'd like to revisit that engine, and build an eleven second Tune Port Injection version of it using the EBL P4, and forward the completed Bin to Dynamic after getting the time slip. I already have most of the parts, just need a different cam (solid), as well as change a few other things around internally because it will need to take the abuse of higher RPM. There is no reason why that engine should not run 11's running TPI built the right way. My wife was actually egging me on to do it... out of all people.

- Rob

Edit: Would also like to do something for the 2.8 and 3.1 guys as well....

 

That right there makes it all worth it. Your wife needs to talk more with mine. LOL That would be a cool project to do... Need more boost!

 

Cool stuff. Well, I have direct access to a very accomplished fabricator, (and I'm thinking about buying a TIG for myself soon) and could probably fab up a somewhat stock looking air box at some point.
I'd still be keen on an Offy manifold or tunnel ram.

 

Oh heck yeah, and what's scary is that Dynamic EFI offers an upgrade to run four TBI injectors for that cross-ram or tunnel-ram manifold, so ideally someone could upgrade to two injectors per throttle body off of the LO3's, but with four 90# injectors, and now we're talking some serious horsepower, even without the need for the supercharger. That would be a screamer for sure. I'm ready when you guys are...

- Rob

 

Nice project Ray. I think this is what you were talking about when we last spoke? That would be pretty cool. I was going to do something kind of like that, only with the Renegade and adapt it to two twin TBs with a CF mechanism. I know that the EBL is capable of doing four injectors and with only doing four 80s, should be enough to fuel a 421 inch motor or bigger? Hope you get around to it in the future.

 

Guys,

I just happened to drop in here and have looked over the thread. If I can be of help, let me know. I originally did beta test for RBob and EBL years ago using my 84 Xfire Corvette. I modified the motor to try and recreate what Grumpy had done a few years before on a Firebird I believe. With roller cam, TFS heads and TPIS headers, I was able to get my car to a 13.3. 1/4 mi. I would trap ~ 104. This was using the stock Xfire manifold ported, and 2.13” TBIs. Using the 90# injectors in parallel. I may still have the bins from that time.
Let me know.

 

Hey Dominic, haven't seen you on for a while. Thanks for the post. As you may know, Ben73 is the fasted NA CFI motor that I know of and running 12.23 ET. I'm already at mid 12s now and working with Street Lethal to go as fast or even faster and into the 11s. I've been chasing Ben for some time, but now maybe even going faster, who knows. The tune is coming along, but have stopped for now since it is just short of being hotter than the face of the sun here in AZ now. Will start again as the weather cools down under 100*.

 

Hey Buc,

I am usually in the DIY Prom forum. Just happened to come by this way today and saw this thread. Brought back memories. IIRC
Ben73 had a 383. I kept the stock block on mine and was still running everything through a stock Y pipe w cat. I’d also converted to a ZF6 trans and Dana 44. My experience w the Xfire has come in handy tuning the LT5. Mid 12’s don’t take much modification w that motor. Headers and top end porting. The difference is trap speeds. A top end ported LT5 is going to be in the 112-114 trap. Its just getting started at the 1/8 mile. 😳🙂

 

You'll hold the title soon, no question. Your engine is very efficient, you built it extremely well. I started messing around with my old 305 again, pretty sure I can squeeze an eleven second ET naturally aspirated and running the stock TPI system. The horsepower is there. Been tweaking a low octane tune this morning, have timing way way down because it's literally running on ****, and was pinging at 25*. Yes, 25* lol. Thank you Wawa pump gas. Getting 255 g/sec low to mid 5000's at around 60 to 65% DC which is about 320 Horsepower with this tune. Normally see 255 g/sec in the mid 4000's running another tune, as well as 100--kPa across the board. Secrets secrets lol. With this one, will see DC in the 80 to 85% range at 6000 to 6200-RPM, and upwards of 90% to 100% with the other tune, as that is where this cam shines. Long story short that is about 415 to 435 horsepower depending on which BSFC you use; modded heads and big cam, though. You 383 CFI guys better step it up, don't get embarrassed by an eleven second naturally aspirated 305 TPI. Now if I can just get this thing to a damn track. Rev limiter set to 5600-RPM with this one, timing down to 20* before it hits the rev limiter, then goes down to the teens.

- Rob

 

WOW! That's AWESOME Rob! Still a bit skeptical about the 11s, but I have faith that it can be done. I was looking at a gear change last night and may just pick up a new unit just in case I need it to launch the heavy beast better. I would love to see a 1.60 or better 60'. Don't get too crazy with the 305, I don't want to chase that one as well. LOL Nice work Rob. I also ordered a Draggy last night to test out my progress to some degree. and on another note, I ordered some other fuel line changes, fittings, hose, tools etc...for the future when it cools down a bit. A little more "bling" not chrome stuff though under the hood. Maybe it will add 5hp more. LOL Oh, and my new TB boring project that I'm doing to make them larger is coming along nicely and I went to lunch with my friend who did my motor machining and runs on the TV show No Prep Kings yesterday and was talking about injectors, big injectors. He gave me a name of a guy/company that also races on the show and said he can make any injector I want. So, show me calling to see if I can have custom rated CF injectors made. How cool would that be...true 90# injectors at 13.5psi or even 100# injectors? Think of the possibilities if that kind of stuff was available.

 

You'll be in the 11's, no doubt about it. I've seen the air flow data, and your duty cycle. You just need to stick the launch, and its yours. Don't be surprised by how deep into the 11's you're going to go. Yeah this 305 has been a fun engine. It's just a testament as to how crappy Wawa gasoline really is lol. 25 freaking degrees (my static compression is only 9:0). Here I am convinced it was the Latency playing games with the timing, or the LT1 knock filter, meanwhile it's the freaking Wawa **** I filled it with this morning...

- Rob

 

11s has a nice ring to it...for a CF motor. Still thinking of going to a 3.73 gear though. My TC should be fine, but if I need to, I can always restall it for $300 to anything I want. Can't wait until it starts to cool off, I have a ton of work to do to get the car ready for this winter at the track. My friends wife gave me the bug again after watching her play with her 77 at the track Saturday night.

 

Dragy arrived today. More stuff for the tune data.

 

Replaced my "nice and shinny" fuel hardlines with braided fuel line hose and new fittings. The hardlines were causing some issues with the new tune. I've seen this issue happen on two other CF cars, a 82 and a 84. After replacing the lines, the issue goes away. I guess you could install a fuel damper, but that would be just that much more modifying and finding the right part and I didn't want to do that. The new hose is a simpler fix IMO. Just in-case someone else wants to do this, this is how I did it. Enjoy!
BEFORE


AFTER

 

That brings back memories. I used braided lines on my 84 also, although nit as neat as urs. I also found that having a very stable mounting point for the Aeromotive VAFPR was also very important. I used a bracket more rigid than what I see in the pics which looks like the one they give you.
What issue, exactly, were u experiencing?

 

Hey Dominic, the issue I was having and like others that contacted me was that the motor would "stumble" and "hesitate" like it was running out of fuel at certain rpm ranges with moderate acceleration and if I gave it more gas, it didn't want to get out of that condition until I hit it and then it would take off like a rocket. It would be less if I was very light on the acceleration when leaving a light, but it had to be very deliberate for it to be less of an issue. My old tune had this issue, but VERY slight. and it didn't really affect or bother me. I do not know why it was less on that tune. With this new tune, it was VERY prominent at off idle running. I'm only on bin10 of datalogging with this tune and I did try it before I changed the hoses and it was still there. Long story and the first I heard about this was when a owner of a dyno shop in OR called me and asked about this issue on an 82 corvette they were tuning and couldn't tune it out and also has to do with the length of the vacuum line to the FPR which affects the rpm range at which the issue happens. The shop sent me a vid from some PHD who did a study on this phenomenon and explained what is happening and why. I have the vid here somewhere, but I would have to go through a lot of stuff to find it, but it is very good and if found, I will post it. It's kind of like a water hammering affect, kind of. That is why I think auto manufactures used a fuel damper on the fuel injection motors early on because of this issue and saw this issue with the hardlines, fuel rails etc...

In all the cases of this issue including myself, going to a rubber hose system, seems to minimize the issue so that the injector pulses are absorbed by the hose whereby the hardlines only amplify the issue. As I mentioned, after the installation I took the car out for a quick ride and it worked like it should with no issues at off idle running like before with the hesitation or just hanging without going smoothly. I need to do a little more testing to be a sure 100%, but it was 113* when I went out...WAY TOO HOT! I think I'm good to go right now though. BTW...What did the heavier duty bracket for the FPR do in relation to function do? Curious. Yes, mine is stock from Aeromotive.

I hope this helps or explains what was happening.

 

I brought this up a few times on the DIY_PROM board with no response. The problem is real. I had it occur once the CPE lines hardened up (and started to weep fuel). At first, no issues, tune was great. But as time went on, and a lot of different setups, injectors, FPRs, ICMs, you know, testing different items.

The tune went south. It was due to the CPE (cross linked polyethylene?) lines got hard. They 'crackled' when flexed. Moving to soft Viton lines reduced the severity of the stumbling/tuning issues. There are fuel pressure dampers easily available for port injection setups (fuel pressure difference).

But nothing for TBI at the lower pressures. Many OEMS run fuel pressure dampers on their MPFI vehicles.

It has to do with the harmonics of the injectors opening and closing against the fuel delivery system.

RBob.

 

I WISH I had seen that post earlier Bob, I would have replied for sure. Ugh! The issue appears to be of the same type of thing, but these were hardlines, that were not cracked or weeping...but it definitely was NOT good with the fuel system with the new tune. By changing to the rubber, steel reinforced nylon braided lines that are also E85 compatible, the issue has gone away. You are right though Bob, it is a harmonics/hammering. issue. The guy at the dyno shop said he tried adjusting the injector PW and only marginally helped. So, the fix is finding a damper that would work with the TBI system or changing to this other type of line. Only time will tell if this holds up and continues to work.

 

Buccaneer,

Oddly, I may have been experiencing a less obvious version of what u had going on w ur tune. I recall having the VAFPR basically cantilevered using the bracket provided by Aeromotive. I would watch the regulator vibrating at idle, which was exaggerated due to the cam lope. I later decided to re-arrange the fuel lines and clean things up. As part of that I used a much stiffer bracket eliminating the vibrating. I found that fuel pressure appeared to be more stable, and that the motor operation was noticeably smoother.
So this many years later, it seems like I wasn’t just imagining things.

 

Bob, how long had passed before you experienced a failure of that hose? I guess PTFE hose could replace the current hose I have, but it is stiffer and the way it is routed now would have to change I believe...and then there;s the new fitting cost and the new tools to install the fittings. It just never ends.

 

It is hard to say how long it took for the original CPE lined braided hose to fail. It was slow over time. At first the tune was fine, but as time went on things kept going further down hill. With a car that I didn't drive often it is difficult to see when/how things deteriorate.

The fumes got really bad and with other cars I had switched to PTFE lined hose. The hose cost wasn't bad but the required fittings took some dough-re-me.

So when it came time to do this car I was originally going to also use PTFE lined hose. But found the Viton lined hose that could be used with the fittings I already had. Made the cost a lot lower. In the end it was just luck-of-the-draw that the hose was softer and also fixed the tune issue. I didn't know this was it until about a month later.

Same as you a x-fire tuner called me and mentioned the same tuning issues. Stumbling, rich, then lean, sputtering, changed with the phase of the moon. Tune was going in circles. He tested the fix by adding about 5 feet of rubber line between the feed line and the main TB. Fixed it right up. The issues were always in the light to medium cruise range.

Here is the hose I am now using:

JEGS Performance Products 111911 - JEGS Pro-Flo Extreme Braided Hose
Pro-Flo 30R9 Braided Hose

Looks just like the stuff you switched too. If so and your tune is good, I'd stay with it.

Had the car out today and the tune/driveability is much better. Been way too long since driving this car, with covid and all...

RBob.

 

Here is the braided hose I originally used. This is the stuff that hardened, weeping fuel fumes, and failed over time:

Russell ProFlex Hose -06 AN
308 Stainless steel covering for a more attractive installation
CPE (Chlorinated Polyethylene) synthetic rubber inner liner

It is fully stainless braided on the outside. With a CPE (Chlorinated Polyethylene) liner. This stuff even though rated for all fuels doesn't hold up. It is bad news. Never use this type of hose for fuel.

So far the Pro-Flo 30R9 Braided hose It was replaced with has been good to go (5 - 6 years). No fumes and still as flexible as the day it was installed.

RBob.

 

Excellent Bob! I will check into that as well. Was that hose hard to bend? Do you think that hose will make the two short hose lengths (front TB) in my pics I had to make? I didn't want to do that, but didn't really have a choice with that. I wish that I knew you had run into this before I went through this, could have saved me more grief down the road maybe, but hey, it is what it is. All my hose and fittings came from Vibrant. I will call them and ask some questions and see what they say. Thanks for the info Bob.

 

The Pro-Flo 30R9 hose is very flexible. Jegs claims a minimum bend radius of 2.5". You may be able to use an angled hose end to increase the loop radius.

RBob.

 

Thanks Bob and I'll do some calling when I get back from my trip. At least it looks like you use the same fittings as what I just used, push on type.

 

Interesting posts guys. I've been running flexible lines simply for economics - ha. My VRFPR though sits on a not so stable bracket, wondering if that has anything to do with a lean spike I get on initial WOT. BTW - I'm looking at AFR's in the above logs and seeing 8's ??? and 10"s - wow isn't that a bit rich? Should I be shooting for those AFRs under WOT?

 

I had/have the wideband disconnected from the EBL, and reading only on the gauge...

- Rob

 

I take it you are running an EBL, right? So you can tune it, right? 8-10 is pig rich.

 

Tom, I think he was talking about the EBL analysis screen shots that I added above during the logging. He might be looking in the Wideband column and seeing extremely rich values. That's mainly because I don't have my wideband connected directly to the EBL system, but I do have it checked off in the EBL Preferences tab which is why it is showing a value, albeit a rich value. Cartrax, ideally you will want to focus on the INT/BLM values with the above logs. However, for wide open throttle using a wideband, you will want to shoot for a 12.5 to 12.8 AFR.... naturally aspirated.

- Rob