That.. Doesn't make any sense.

When the injections alternate the pulse width has to double to deliver the same fuel.

Unless.. You don't have EAE enabled do you?

-- Joe

 

i had to make a bunch of changes to the ve table at the same time due to the race gas so that could be it. the race fuel had really richened the motor up to the point it was puffing smoke , and dont think so

 

You were not rich, you had incomplete combustion. High octane fuel burns very slow, so you must light the mixture as early as possible.

You needed more advance, not less fuel.

We used to run 110 in the jet boats.

Unlike cars, jet boats don't run max rpm for only 10 seconds. They run max rpm for hours.


-- Joe

 

Do not listen to that advice lol

 

No?

While higher octane fuels naturally have more heptane which slightly alter the Stoichiometrical qualities, the more likely scenario is incomplete combusion.

Correlation does not imply causation. The problem with most tuners and hot rodders is they don't understand the physics behind the alterations they make, and misinterpret the end results.

But what do I know.

-- Joe

 

Trust me you are wrong on this.

You need to go out and do things instead of reading about or providing theories of how things work. You might learn something at your age lol

Yes it may need more timing but it will change the air fuel ratio depending how far off the properties of the fuel used

 

I think things just work different for you, like commanding injector pulsewidths that are shorter than the actual open time of the injector yet getting proper fueling.

If he provided us with a link to the actual fuel used, I could quickly calculate the actual Stoichiometric difference, but I doubt it's enough to make major difference in his VE. Perhaps a little, but again more likely than not he was lighting the mixture too late.

Flame travel, plug location also has a huge role to play. It's not just slapping parts together, it's science.

You are a mechanical engineer, yes? Do you just build a bridge and see how it fairs, or do you calculate your load paths based on known data?

I'd rather be Tesla than Edison.

-- Joe

 

He said he used vp114 which is vp c14. The specific gravity is .696 to pump gases .735+ depending on ethanol contant. Stoich is said to be 15.08:1

If you want to believe the same fuel jetting is gonna be used here, go ahead and drown your engine out

I have been there done that with pump 93 to vp110 which has same stoich as c14 but heavier at .720 specific grav and i had major changes to fuel jetting to make max power, with little to no timing changes

Verified track and dyno tests

Tell me again i am wrong or show evidence from testing you have done! Enough with your bs

 

Since the ECM has two fuel drivers it is best to use them alternating with big injectors.
I am running 58 #/hr p&h in stock 305 TPI at 650 rpm at 45kpa at about 2.0 ms in alternating bank fire mode. That is just to give you something to compare to.

I used to think doing alternating bank fire and switching to dbl fire bank when the PW got big enough was the way to go. I thought it through, then decided to stick with alternating bank full time.

You mention a cyl sucking fuel from a port injector near the cyl head. In order to pull this fuel you need a source for air to come from (try plugging a vacuum as an example, i.e. intake valve must be open).
What does it matter if a cyl not firing got sprayed once or twice in 720 degrees? If the "stealing fuel" theory was correct then the fuel would still be robbed by other cylinders no matter how many times the injector was sprayed. I don't buy this theory, just as I don't buy the the whole turbo engine needing bigger valves spring due to pressure. It is all about the pressure differentials.

 

joe it needed the ve change , im running 30*+ of ignition at idle

and yes its vp114

 

I didn't say the same jetting, I said the difference wasn't that much. Not enough for him to claim it was "puffing smoke".

"Puffing smoke" is a sign of incomplete combusion.

I understand you've done a lot of testing on and off the dyno, but interpreting things that are the results of changing settings that you don't entirely understand isn't a perfect science. These types of experiments lead to a blown up engine.

It's not BS. It' science. Higher octane fuel, especially 114 leaded burns a lot slower than lower octane fuel. That is why it's used - to prevent pre-ignition.

At the end of the day I don't really care about convincing you, but I'm worried that future form members might read this thread and think that the burn rate of fuel is irrelevant.


Dave, what percentage of change did you make to the ve ?

30 degrees at idle?!


-- Joe

 

Yes because you are flooding the engine
It happened to me as well. Ignition system changes can help fire it off and reveal how rich it really is if the wideband can read that low lambda

Burn rate was not discussed here and although relevant in chosing a fuel, i dont see how one could conclude that it didnt matter. You just seem to be changing subject. I am well aware of burn rate and did not feel that was something to bring up here. Thats for another discussion, wether he needs 114 oct for this or not

I was debating the exact situation here on his motor using pump 91 to 114 vp. Very similar to what i have done

And 30 deg at idle is not much in a big cam higher rpm idle sbc with heads with chambers like that

 

I kinda wanna peel this off into it's own thread as to not muck up his project thread, since it's only loosely related. But anyway.

I think the theory (which didn't originate with me BTW, I'm still in study) is two things can happen:

1) That in simultaneous since all 8 are firing at the same time, the firing order is irrelevant and intake valves are opening and getting nearly equal amounts of fuel. However, when they are alternating you could potentially be loading up some cylinders that might not fire for quite some time, or not enough fuel on others.

2) On alternating you are dumping a larger amount of fuel at a time, with the potential for it to puddle and then get sucked into an opposing runner depending on the intake design.

I'd love to see a visual model of this.

I'd love to start a thread on this because I'd like to discuss it deeper, but most people on the forum don't care how it works they just care that after banging on the keyboard long enough the car runs.

Hrmm. Is this theory that the valve will have a hard time closing? The only time this theory could apply is when the intake valve is trying to close, since any other time there will be pressure in the cylinder. I mean, I'd have to visualize the cam specs but I don't think this is possible.

Or is the theory that at max lift the valve will float from the added intake pressure stream? I don't think that is going to happen either because the pressure should equalize.

-- Joe

 

Please re-read post # 1353.

-- Joe

 

The valvespring thing is interesting. Some say no extra pressure, some say do. Imo it might be a valvetrain stability and harmonics issue. I tend to think that opening and closin of valves in higher cyl pressure environments may require more spring for a given cam lobe than in a na application.

I can say i have seen alot of guys run turbo setups, that exhibit power loss and valve float characteristics at higher boost levels than low. My 305 car did this on stock cam and springs. It increased power to about 8-9 psi then ran identical times from 10-20 psi.

I believe it was lack of spring but never got to test it

Pushrod stiffness, rocker geometry and spring harmonics also change how the valvetrain behaves. Testing this soon on a 1350 whp single turbo 414 lsx. Low boost power carries to 7000. Springs arent shimmed to near coil bind which they should to help fight harmonics, and also give it proper seat pressure. High boost made more power early in the rpm range but fell like a rock after 6000. Clearly something goin on and it wasnt the exhaust side. Tried a bigger turbine wheel turbo and ar ratio

 

Still got that Import Tuner side in you I see...

 

with my intake i really doubt one cyl is going to pull fuel from the cyl nexto it

now on something like a siamiezed tpi or efi single plane i might worry about it

 

That's basically what Matt Cramer told me, it really depends on the intake design. I bet my miniram, or some of the singleplane intakes I used to run would more likely to have that issue than an HSR or a TPI. Even a siamesed TPI I don't think it's going to happen.

I really wish I had tried a dual-plane intake on this car with a quad injector TBI.

That green color looks cool. I'm still undecided what color to paint my '75 Stingray. I was thinking of Yellow, but I've been looking at brand new yellow vettes and having two yellow cars would be dumb.

-- Joe

-- Joe

 

Only way to know if its not getting the fuel is to have 8 egt and 8 o2 monitoring a complete pull. Even then that may only tell if its air distribution. Else you are just guessing and theorizing. No doubt intake reversion is a problem with some big cams, at low rpms, so it stands to reason perhaps some cyl do get some fuel from others but i cant see that happening much if runner length is decently long. Miniram perhaps, but they seem to have air flow distribution issues, i dont know if fuel stealing is going on

I will say that efi units that can control injector timing can greatly affect power production in some applications, or atleast improve fuel consumption efficiency

 

Yeah, I don't know why I bought another Miniram. Looking at my notes from 2006/2007 when I had one on my C4, it was always a PITA to tune with the 306 degree cam.

Yeah.. I know. It's not a money thing, I could upgrade to full SFI I just don't have a good solution for the crank trigger. I have a 36-1 wheel I used when I was playing with DIS, but I don't like it sandwiched between my pulleys (not hub centric) in a supercharger app. As it is my pulley has enough run out. If the crank snout snaps off it's game over.

If I decide to use the LS motor I bought a few months ago, I'll go SFI/DIS then. For now, what I have appears to be working.

Anyway, none of this really matters for Dave's build.

-- Joe

 

Perhaps, but what were you tuning it with though, which system?

Sell all your projects Joe and buy something new and fresh.

 

My C4 or the Formula? The C4 was Super $8D, '730 ECM. Open loop idle, closed loop above 1500 RPM.

The Formula is Megasquirt. I was running double fire batch on the Megasquirt like $8D, but I've since switched to alternating fire on Junk's suggestion. I asked in the EBL thread how those guys are doing it but I havn't seen a response yet. Not because I'm looking to switch to EBL, but simply because I'd like to get educated on what works and what doesn't.


Nah. When I was young and didn't have money I couldn't afford to own multiple things. Now I just keep them in storage. I've got a lot of stuff that I don't talk about on the forum because it's just way off topic. I'm very active about my Formula because this is thirdgen.org. I don't really post about any of my other stuff.

My biggest problem is not enough shop space. I've got two garages on my main property, and both are full. I told my wife when the horses finally die of old age I'm gonna knock the barn down and build a 60x40 shop. If I live that long haha.

-- Joe

 

How the EBL guys are doing what? Fueling?

That is your passion, you should do the shop. For me, the GTA will now be a breeze to complete because I am doing a RMT, but after that I am finished, and I am serious this time. I'll race whomever I promised to race on this board, but then I am done. I said no more vettes, but one more for next Spring lol, just not sure what year yet. I don't wanna lease a new one, insurance is a waste. Maybe a Grand National or TTA if I can find a good condition and unmolested one, but more than likely the vette. Do the shop Joe, this way I can drop my car off to you for you to work on, I'll just sit back with corona in hand lol. I am just about done wrenching...

Edit: Woops, sorry Dave, back to the build...

 

Yes, is it single fire when pulsewidths are below a certain value, is it double fire all the time, or is it bank to bank.

What happened to the F1 ?

-- Joe

 

I started typing, but then I just figured I would link to the website...

http://www.dynamicefi.com/InjectorDriving.php

I bonded with the Buick after I just swapped engines for it. It's funny with the GTA, was back under it again and I was looking at the over the axle tube I fabricated from the stainless y-pipe end to the muffler inlet, and there is a lot of room down there. I can get a RMT done very fast, and for a lot less. Gotta get it back on the road to make some additional room in the front garage, wanna put it out back somewhere...

 

Thanks. So it's just double fire like a stock '165 or '730. Interesting.

I wonder who has the largest injectors on an EBL. What are you running for injectors on the GTA ?

Yeah. There is a lot more room out back for a single turbo. It's just the 9 miles of intake pipe that drive me crazy.

-- Joe

 

I had 30's, then 60's, then 42's which I just sold, now back to 30's while naturally aspirated. I hear you about the intake tubing. Also, with the 1 3/4" primaries on those headers, and with twin 2 1/2" tubes leading to a 3" Y-Pipe, I think the turbo will do very well in terms of any lag issues. Sadly, I'm more worried about the oiling both to and from the turbo...

 

I should move these posts to your thread, but how do you plan on routing the intake pipe back to the engine with the long tubes?

I'm sure you'll get it done, but the amount of fabrication, oiling, etc you are going to have to go through.. Just buy a used blower and make your own bracket.

-- Joe

 

I tuned 60's on an ebl, no issues. Procharged 383

 

Which 60's ?

What was the dead time?

What was your idle pulse widths?

The other day you said you ran injectors with a stable AFR at idle in the .8 msec range, yet the dead time on those injectors is higher than your commanded idle pulse width.

-- Joe

 

I dont have that information. It was a customer who brought the car and laptop with ebl to me to do and i tuned it. No longer have access to those figures but i believe he said siemens 60 lbs.

The deka 60's are 1.3 ms open 0.7 ms close. Min linear pulse 1.5 ms

Log on mine said .9's command pulse but deka siemens 80's have same information. 1.3ms open .7 close. Min linear pulsewidth 1.9 ms

I dont know what to tell you but it worked fine on 730 ecm hardware

 

Your data is correct. It is staying open longer, obviously.

Where I find a problem is the statement that you had stable AFR at those commanded pulse widths. That shouldn't be possible.

I found this post from RBob himself, whom is obviously the authority when it comes to the Delco stuff: https://www.thirdgen.org/forums/diy-...ml#post5829341

What he doesn't say however, is whether or not the ECM switches to a single fire mode when the pulse width commanded is less than the minimum pulse width.

My car idles in double fire mode "fine" too, but the AFR's are not stable. The exhaust stinks and pops. If you try to back off the fuel you get erratic idle speed.

On alternating double fire, I can idle at a much more stable lean AFR.

-- Joe

 

Stable idles, no smell, no pops and cracks, i can command 14-16:1 air fuels as i please. Data may say its not suppose to happen but thats what was happening

Idk if the 411 changes things with sequential but i have no problem leaning out the 110lb at 43 psi base injectors til i stall car out from being to lean. I wouldnt beable to drive 2000 miles a year on fouled plugs if idle afr wasnt stable and lean. Perhaps the sequential 411 is the reason there.

But i drove the 80 lb car 730 for 3 yrs with 14's to 1 idle afr's. Plugs were showing somewhat darker than tan meaning rich but not fouled. I could have went leaner i think

 

Sequential is entirely different.

I'm confused. Was the 80lbs in a P4 EBL car or your car with the $59 code? $59 does single fire at low RPM.

-- Joe

 

80's were in my car with code $59 on a 730

The 60's were in the ebl car but not 100% sure what injector brand, i think siemens 60's

Edit: it was siemens 60's

 

starting over from scratch on the megasquirt , threw in my ms2 cpu as a last resort not having any luck comming up with funds to grab joes ms unit
car idles much better at 1200rpm then it did at 900.
need to adjust the start retard so it doesnt pop when it fires , and need to dial back the ae a lil bit before i can take it out on the street tonight

 

Did you take it out on the street? Any luck getting the idle down where you want it to be?

 

no i didnt get it out im all tied up with 4 other projects for customers atm , buick electra with a 3800 project , ford 150 4wd clutch job , headgasket on a gran prix, and a trans swap on an alero

i got the idle down to 1,000 rpm , not going any lower with it , its a nice day so farm so hoping i can get the time to take it out for a drive , i really need to use up the tankfull of vp114 i dont want it to sit all winter with that in the tank

 

WTF man, you had the idle nice and low back in March. What did you change?

 

cam, the nice idle was on the 224/224 single pattern cam that went all egg shape on me

 

car might be sold soon , lets just say if it goes ill have a big big smile on my face , if all goes well ill have made a ton of money on the deal

i will admit its going to be hard to let go of this one , but ive already located a replacement , and with the money im getting i can build 3 more if i want to

 

Buy a vette

-- Joe

 

thinking about a c5

 

Can't go wrong, and they are getting cheaper and cheaper.

-- Joe

 

Blasphemy lol. I predict you're keeping the Camaro. I see you put up your old video compilation on youtube recently. Remember this one? Two favorite scenes; 0:35 & 1:35 both at e-town. Back when we thought 11's and 12's were fast lol. Wonder if Steve still has that car. Time flies...

 

i dont know i got osmone seriously interested in it and they are going to drive up from vegas to look at it soon inprice in the range of 1x,000 shes gone if he wants it

 

Unfortunately Corvette's lose value (which is of course good for the buyer). unless we're talking about specialty Corvette's. C4's can be had for dirt cheap, and C5's are not too far behind. A far cry from what they were brand new. If you're really looking into a C5, then I say go for it, you get a lot of car for the money, and swapping in a boosted LS3 like Charles did is a no brainer, the engines make 8 seconds too damn easy. Just be sure it's what you want to do...

 

I think he did a 5.3, not an LS3.

I was looking at 427 CI LS engine combos the other day that make 650 horsepower and run on 91 octane. That would be a heck of a street car, and look factory.

-- Joe

 

Yeah I just looked, high 8's with a 5.3. You can get those engines for very cheap too. It looks like he mostly added fasteners, but retained the crank, rods and pistons. That's a terrific engine. I'd like to explore a roots blower inspired engine for my next Corvette though. Don't want it to run single digits, although would like it to be capable of it. Just a high ten, low eleven Corvette with excellent street manners and sweet exhaust note, but not too aggressive. Meh, I guess I'm getting older...

 

I have a 5.3 on a stand in the shop too. Not sure what I'm going to do with it.

I'm kinda in the same boat. I wouldn't mind an 11 second pass once and a while, but I really just wanna drive the car on sundays. If I have time. I've only put 50 miles on my bagger this year, and it's only got 1600 miles on it total and I bought it new in 2012. I guess I work too much.

I thought about buying a C5 but the electronics kinda worry me. They are getting cheap, same with the LT1 C4's.

-- Joe