Timing Table

[BLG355]

I've been looking for a good timing table for some time, and I ending up using one Brian617 posted a while back, but modified it to suit my needs. Basically, at certain points while driving the truck just felt flat, so I made the timing more aggressive and increased it overall and more so at certain spots. I looked at a lot of timing tables all over the place, and a bunch here, and they just don't seems to have near the timing I am using. I tried a bunch but the engine feels very weak midrange, and I modified brian617's table and was able to eliminate the flat spots almost completely, I am thinking about tweaking a degree or more in a few spots and see how it feels.

Most other timing tables I tried, even the Vortec one, just don't have the throttle response or the feel I was looking for. I am looking for some input and thoughts from you guys, do you think I am way to aggressive on the table or is it ok? Should I tame it down a little...or a lot. The truck runs and pulls great, I was thinking about trying more to see if I can find some knock and then back it off a few degrees. Any thoughts, comments, anything at all...is greatly appreciated. Thanks.

BLG

[steveo]

that isn't a very aggressive table, but then again it's a truck.


I was thinking about trying more to see if I can find some knock and then back it off a few degrees

you're better off increasing it in a reproducable range, and monitoring for an increase in vacuum (or decrease in KPA, whichever way you want to look at it). when vacuum stops increasing, you're at the ideal point, just stop.

once you've determined a few points in the table like that, you can usually interpolate the rest of the table and figure out how the curve should be, and do fine tuning if there's any resulting knock.

[BLG355]

Thanks for the reply. I was being conservative at first because of the weight, but i started slowly increasing timing to roughly where it is now, and have since brought the timing in a lower rpm's with good results. It seems like most of the tables I found max out under 20 at WOT and the part throttle stuff was almost 15-20* less than what i am at now. I have very crisp throttle response now and it feels very good driving it.


BLG

[brian617]

Been to busy lately to fiddle with mine, although I keep thinking about adding or changing mine too. Glad to see that the same basic shape is working for you, makes me want to throw some more timing at mine. I'm constantly looking at other maps eyeballing the shapes trying to understand more about them.

[BLG355]

Been to busy lately to fiddle with mine, although I keep thinking about adding or changing mine too. Glad to see that the same basic shape is working for you, makes me want to throw some more timing at mine. I'm constantly looking at other maps eyeballing the shapes trying to understand more about them.

It really worked good for me, especially compared to some others I have tried. For my build, bringing the timing in at a lower RPM really makes the truck feel more responsive. I'm currently swapping out 7.4 TB and injectors so I want to get that nailed down before I change too much else at the moment.

BLG

[Fast355]

It really worked good for me, especially compared to some others I have tried. For my build, bringing the timing in at a lower RPM really makes the truck feel more responsive. I'm currently swapping out 7.4 TB and injectors so I want to get that nailed down before I change too much else at the moment.

BLG

I noticed the same thing bringing in timing earlier on the Vortec head engines I have tuned.

http://i243.photobucket.com/albums/ff172/Fast355_album/attachment-2_zpskhqldydp.jpeg

http://i243.photobucket.com/albums/ff172/Fast355_album/attachment-2_zps75x1guko.jpeg

[BLG355]

Fast355,

I noticed 30 degrees at idle on your one table...is that really at idle or is there a separate table for that?

BLG

[Fast355]

Fast355,

I noticed 30 degrees at idle on your one table...is that really at idle or is there a separate table for that?

BLG

Separate table, but I use the same values in that table. Never seen a need for different values as it makes the transition pretty abrupt to go from no timing to full timing off-idle. Same reason I do not use ported vacuum on the older carb setups. Idle generally ends up best around 26-34* depending on the heads/cam/compression ratio.

[BLG355]

ok, I'm going to try this with mine. I have two different tables and my idle never feels very good. I've tried it from 18 to 23, but never any higher. I am going to bump it up and see how it goes. Thanks.


BLG

[Fast355]

ok, I'm going to try this with mine. I have two different tables and my idle never feels very good. I've tried it from 18 to 23, but never any higher. I am going to bump it up and see how it goes. Thanks
BLG

I usually advance the timing at idle until the IAC/MAP stops dropping and then retard the timing 2-4* from that setting. One thing I have noticed is the idle timing variation has less effect the more closely optimized your idle timing is for the setup.

[PJG1173]

WOW, I have always been reluctant to advance mine more than 19 ~ 20* at idle. might have to try it too.

[Fast355]

WOW, I have always been reluctant to advance mine more than 19 ~ 20* at idle. might have to try it too.

The last LT4 Hotcam Vortec 350 that I messed with, liked about 30* of timing at idle.

[rsicard]

The last LT4 Hotcam Vortec 350 that I messed with, liked about 30* of timing at idle.

Have the same setup Vortec 350 with LT4 Hotcam. Also have 454 throttle body. Question, do you check the timing on the balancer or just ignore it and use Tuning Software to set the timing table/map? Have compared balancer with TunerPro ECM commanded timing and found no relationship between the two. Maybe should just set the tables in TunerPro according to you tune and then set the distributor to attain the desired values. Please advise. Thanks.

[steveo]

idle timing should be set just like the rest of timing map, to the point of maximum vacuum and no more.

[brian617]

Fast, any chance you could screen shot your MAP vs RPM table in 3D view so I can eye ball the shape?

[Roadknee]

Barry - any chance I could talk you into posting a datalog of a good WOT 0-60+ mph run on flat road?

[Fast355]

Fast, any chance you could screen shot your MAP vs RPM table in 3D view so I can eye ball the shape?

I forgot that you asked me about this, I will try to get a 3D view of both for you.

[BLG355]

I think i got one i can post from the other week with a WOT run on it. I will look tonight when I get home. I assume you want it with that timing table I was using correct in the post correct? I recently brought the timing in at even lower RPM and I am currently going form 61# to 80# injectors and also recently(within the week) installed a 454 throttle body so hopefully I can bump the RPM's up a little more, I had it shifting around 4750 or so because of going lean and pulling 4" of vacuum @ WOT at 5,000+ RPM. I am going from 61# injectors at 22psi to 80# injectors at 18psi.

BLG

[Roadknee]

thanks Barry. I have a 1995 K1500 too and am curious how the various combinations run. I'm running the stock LO5 with some tuning and can 0-60 in 10.0 seconds with 265/75-16 tires and 3.73's. 355chev with his Vortec headed TBI is down to 8.0 seconds with knobby 33" mud tires. I think once you get the fueling correct with the new TB and injectors yours will be a beast!

Are you running a wideband yet?

[Fast355]

thanks Barry. I have a 1995 K1500 too and am curious how the various combinations run. I'm running the stock LO5 with some tuning and can 0-60 in 10.0 seconds with 265/75-16 tires and 3.73's. 355chev with his Vortec headed TBI is down to 8.0 seconds with knobby 33" mud tires. I think once you get the fueling correct with the new TB and injectors yours will be a beast!

Are you running a wideband yet?

Thats moving out pretty good!

My tuned but otherwise stock Vortec 5.7/4L60E/3.42 on P235/75R15s in my 5,800-6,000 lbs (depending on how much gas in the 31 gallon tank) express van ran 0-60 in about 11 seconds while spinning the tires from a stop and shifting too high @ 5,500 rpm.

https://www.youtube.com/watch?v=vc1lHlBLdkw

Now with a alot of modifications to the engine and a drivetrain that robs alot more HP it pulls 0-60 in a shade over 8 seconds even shifting 500 rpm sooner. I also have heavier 20" wheels and tires on it that are 2" overall diameter larger and about 25 lbs heavier per corner. Shifting in the 5,700-6,000 rpm range I drop nearly another second off the 0-60. It really needs a lower gear ratio in the rear-end but I have not decided on 4.10 or 4.56 yet. Negating the larger tire diameter switching to the 4L80E/3.73 is like having the 4L60E with a 3.08 gear in the rear-end in 1st gear and like having a 3.36 gear in 2nd making 1st and 2nd gears overall taller. Factor in the tire size change and its almost like having 2.73s in 1st and 3.08s in 2nd.

https://www.youtube.com/watch?v=-6DZhPN7VHQ

The changes I have made since the tuned but otherwise stock video.

A.) 0411 PCM swap with HP Tuners custom tuned by me
B.) Edelbrock ETec 170cc heads (Cracked the 062 from overheating)
C.) Custom grind Comp cam 215/220 @ .050
D.) 1.6:1 full roller rockers
E.) L31 marine intake manifold with 80mm throttle body
F.) Larger 2002 Express MAF
G.) Doug Thorley Tri-Y headers
H.) Custom exhaust system that goes from 3" head pipes at the headers to 2.75" mandrel bent pipes into 2.5" high flow cats and 2.5" into a dual 2.5" in, single 3" out walker dynomax school bus muffler into a 3" mandrel tail pipe
I.) Swapped the weak 4L60E for a power robbing 4L80E along with a GM B82 factory high stall torque converter
J.) Blew up the 8.5" 10-bolt and swapped in a 9.5" 14-bolt with 3.73s and a factory limited slip
K.) Finally last but not least upgraded the cooling system, 454 G3500 radiator, factory oil cooler, factory G3500 trans cooler and lines, and a Duramax cooling fan on an extreme duty Trailblazer SS fan clutch.
L.) I also used a racetronix harness to supply the fuel pump with power straight from the battery isolater I used to charge dual batteries.
M.) Also have a AD244 alternator, an underdrive crank pulley and a 170*F thermostat on it.

I also did some non driveline related modifications that made the van more suitable for towing, but also heavier at the same time. It has a full 1-ton suspension under it. It has the Coil and Leaf Springs/Control Arms and front brake calipers from a 99 G3500. I put a rear sway bar on it and added an aftermarket overload leaf to the 1-ton leaf spring. I also removed the crappy 5,000 lbs class 3 reciever hitch and bolted a heavier class 4 10,000 lbs hitch under it. I also added a 2nd battery in a diesel battery box on the frame to power all the electronics in the van when I am parked without killing the starting battery. What all this has done has pushed me from ~ 5,800 lbs factory to 6,000 lbs (after the 4L80E/GM 9.5 swap) upwards to 6,300-6,400 lbs. With the changes I can pull an 8,500 lbs enclosed dual axle trailer without worry over overheating or hurting the drivetrain and no longer find myself crawling uphill on mountain passes at 30-40 mph in 1st gear.

[BLG355]

I looked by most of my logs aren't from a dead stop...but I did do a bunch of runs back in February with Datamaster from a dead stop trying to see how accurate the GTECH was, within 4% of each other. But the track doesn't lie so this spring I'm getting real numbers.

Back in February I was messing around with 25psi on 61# injectors and it ran decent(well, really good WOT), but at that time I had no where near enough timing based on what I am learning now. But here are those results, even though I hate publishing anything that I can back up with a time slip, this probably is close. It's from the straightest, flattest road I know and plus or minus 4% it's pretty good. I am really hoping to run high 14's with this thing, but I don't know if it has it in it or not. Being able to launch at just about 2500rpms helps a ton with the performance numbers, if I can get wheel spin under control I might be able to make a go of it. I still haven't bought a wideband yet, but I have a new bung to weld in the headers for my NB and I plan on using the stock location for the wide band once the weather warms up a tad.

BLG

8883

8884

8885

[Roadknee]

Thanks for posting that, Barry. After you the 454 throttle body dialed in I'd like to see a Tunerpro datalog so I can compare apples to apples. Regarding the wideband, 355chev installed the LC1 with great results. It has a WB and simulated narrowband output. He wired the wideband (0-5v) into the egr pintle position (pin B16) of the 7427 ECM. The simulated narrowband was connected to the purple wire of the narrowband O2 harness. One O2 sensor for both functions works like a champ.

[BLG355]

I'm going to have to look into that. I've been wanting to add it somehow, this might just be the ticket.

BLG

[BLG355]

I decided to post a log, I've been messing with it very little lately but I had time this morning. I'm having mega issues with cold startup but once warmed up it runs half decent. I am going to cut the factory air cleaner housing to match the opening of the hypertech bowl and weld a bung in for wbo2 in the next few days. Racing season has started and I got a young cousin that is very new to this so I am devoting a good bit of time to teaching him how to set up a carb and bracket race. Here is the log for this morning. My road I use is right between to fields and with the farmers starting to work them, the road isn't the cleanest and I am getting massive wheel spin, once we get a good rain I will run it again. I really need to get a wbo2 as well. It takes a ton of time to get it just to where it is and I think it's still lean.

BLG

[Roadknee]

Is with the 454 TB, 80 pph injectors and 18 psi?

[BLG355]

Is with the 454 TB, 80 pph injectors and 18 psi?

yeah, the psi is actually 17.5. I'm not so sure about these injectors. mr injector says they only flowed 67# 12 psi but I remember Mark saying before that the cleaning solution doesn't flow as much as gas. at 15psi they flowed 78psi according to him too, so I got the pressure up a little more than that knowing I needed more fuel than my 61# @ 22psi. I might switch back to the 61# and up it to 25psi. the truck ran fabulous there with the small throttle body, the larger throttle body I am hoping will improve some more.

The injectors were from a '89, and the numbers show they are factory 80#, but they did not flow that @12psi according to Mr. Injector. surprising though, I have Napa replacement injectors, meant to replace the ones in a '89 7.4, and they flowed very similar to this.

BLG

[Roadknee]

78 pph at 15 psi should be 84 at 17.5 psi. Mr. Injector has tested several of the 61 pph injectors at 22 psi and they also flow about 84 pph. The little bit I looked at your log it's lean. Several BLM's are in the mid to high 130's and your WOT run at about midpoint in the datalog had the O2 sensor bouncing below 500 mv. Injector duty cycle is less than 75% so I think you have enough fuel pressure. What do you have the injector constant set to? I like to set it at 10% less than the rated flow of the injectors, or 76 for 84 pph injectors.

I saw a slight lean condition when you slammed the throttle for the WOT run. If you didn't feel a bog, I'd leave it alone till you get the WB. tuning AE with WB is much easier.

Did you have the air cleaner lid turned over during that run? If not, was the cold air hose connected to the inner fender? Also, was that WOT run on flat ground? I ask because your 0-60 was 8.0 seconds even with massive wheel spin. Impressive. What gears and tire size are you running?

Finally, with the larger TB you'll want to bump of the values in the line pressure tables to compensate for the added torque your engine will make at less throttle.

[Roadknee]

Just noticed IAC counts at hot idle are high, like 60ish. Open the throttle blades to bring this down to around 10 in park. This might explain the cold start problem.

[BLG355]

Injector constant is set to 86#. I have the rpms set back right now, before I had the 1-2 shift at 5500 and the 2-3 at 5300 but the IDC was up in the 90% range. I backed the rpms down too because it was showing 88 kpa@wot at 5500rpm. I wanted to get the 454 tb on and see if it helped, which it honestly feels about the same except the throttle is snapper now which it to be expected. So, if I lower the injector constant, do I have to change the VE tables as well? This part always seems to confuse me yet.

Air cleaner is 100 percent factory all the way to the fender, didn't mod anything yet. The road is very flat and smooth, but short. Tires are Goodyear Duratrac 235/85/16 with 3.73 gears. truck was factory with 225/75/16. using a gear calc, I was able to determine that going from 29.3" to 32" tires I'd be able to put in 3.73 in place of the 3.42 and it would be the same. I wanted to go 4.10 but I didn't feel like doing the required mods to keep the speed and odo correct.

I am seriously hoping this truck runs 14's. I also have the s10 converter which gives it the stall speed you can see. I know from drag racing, having a good converter stall at the proper RPM's makes a huge difference in ET. The main holdback on it is the cam, it is very conservative but I picked it based on what TBI chips was saying at the time. It's a good cam and makes mega toque and perhaps that's perfect for this 4x4 truck. It's for sure the smallest roller cam I've ever put in any engine, ever. it's good from 1200-5000 but it still pulled hard up to 5500, even with the stock throttle body. I am curious how it will change with the 7.4 tb once I get the tuning closer.


BLG

[BLG355]

Just noticed IAC counts at hot idle are high, like 60ish. Open the throttle blades to bring this down to around 10 in park. This might explain the cold start problem.

I saw that as well and I've been wanting to open them up a little. I'll work on getting that down closer to ten.

BLG

[Roadknee]

Injector constant is set to 86#. I have the rpms set back right now, before I had the 1-2 shift at 5500 and the 2-3 at 5300 but the IDC was up in the 90% range. I backed the rpms down too because it was showing 88 kpa@wot at 5500rpm. I wanted to get the 454 tb on and see if it helped, which it honestly feels about the same except the throttle is snapper now which it to be expected. So, if I lower the injector constant, do I have to change the VE tables as well? This part always seems to confuse me yet.
BLG

The VE table will not accept a number over 100. With a modified engine like yours you have to reduce the injector constant so that VE values under 100 give the engine enough fuel. If you reduce the injector constant and want fueling to remain the same, you have to reduce the VE table by the exact same percentage. Reducing your constant from 86 to 76 would be a 12 percent change. I think you'd run a little rich. Try 79. I think your engine will be happier.

Flipping the air cleaner lid increases airflow a lot. On 355chev's 1995 k1500 it increased manifold pressure from 85 kpa to 90 kpa at 5,200 rpm. The hypertech salad bowl was worth another 1 kpa.

[Fast355]

The VE table will not accept a number over 100. With a modified engine like yours you have to reduce the injector constant so that VE values under 100 give the engine enough fuel. If you reduce the injector constant and want fueling to remain the same, you have to reduce the VE table by the exact same percentage. Reducing your constant from 86 to 76 would be a 12 percent change. I think you'd run a little rich. Try 79. I think your engine will be happier.

Flipping the air cleaner lid increases airflow a lot. On 355chev's 1995 k1500 it increased manifold pressure from 85 kpa to 90 kpa at 5,200 rpm. The hypertech salad bowl was worth another 1 kpa.

If you can get one find a 454 TBI air cleaner with 5" filter lid, duct and fender opening. Its all larger and the 454 air cleaner has a built-in powerbowl from the factory.

[Fast355]

BLG's cam is pretty conservative....

In my 350 Vortec based engine I have had a
203/210 @ .050, 115* LSA
moved to a 206/210 @ .050, 110* LSA
then a 215/220 @ .050 on a 114* LSA

I recently installed a Hydroboost setup and have my eyes on a grind similar to what David Vizard spec'd for Project Sledgehammer.

This is purely a move based on prior experience with this engine and the fact I am putting a 4.56 geared GM 10.5" 14-bolt full floating rear end in the Express along with an 11" 2,800 rpm converter in the 4L80E.

I am planning on running a steel billet core 08-000-09 custom grind on a 108* LSA.

If Comp Cams will grind it that way, I am planning on Intake/Exhaust lobes of part number 3035.

276/276 @ .006
224/224 @ .050
147/147 @ .200
.353/.353 lobe lift
.565/.565 lift w 1.6 rocker
108*LSA
104* ICL

The torque curve on a carbureted 10:1 350 engine with a single plane intake manifold and crappy EQ Lightning 180cc heads was pretty decent.



RPM
TQ
HP


2,600
389
193


2,800
401
214


3,000
401
229


3,200
406
247


3,400
414
268


3,600
425
291


3,800
433
313


4,000
439
334


4,200
443
354


4,400
445
373


4,600
445
390


4,800
443
405


5,000
438
417


5,200
431
427


5,400
423
435


5,600
414
441


5,800
403
445


6,000
391
447


6,200
379
447



Given those numbers with the crappy flowing (compared to my E-Tec 170s) EQ Lightning heads my higher flowing, smaller ports should wipe the floor with that setup.

[Roadknee]

Fast - given your willingness to step up to a custom grind on a billet core, I encourage you to contact Mike Jones of Jones Cams. He is one of the top in the country and in addition to his wealth of experience he utilizes a program he developed that calculates mass flow in and out of the cylinder to optimize cam selection. With your RPM and HP/CI you're in the area where lobe shape can have a significant impact on performance, and different shapes for intake and exhaust lobes are often needed.

http://jonescams.com/

I have purchased a hydraulic roller from him and the quality is excellent. He uses a billet core with a pressed-on cast cam gear so you don't have to run a bronze distributor gear.

[brian617]

The VE table will not accept a number over 100. With a modified engine like yours you have to reduce the injector constant so that VE values under 100 give the engine enough fuel. If you reduce the injector constant and want fueling to remain the same, you have to reduce the VE table by the exact same percentage. Reducing your constant from 86 to 76 would be a 12 percent change. I think you'd run a little rich. Try 79. I think your engine will be happier.

Aren't you just robbing Peter to pay Paul?

[Fast355]

Aren't you just robbing Peter to pay Paul?

No not really.....You are basically adjusting your base pulse width (Displacement or Fuel Injector size) and fine tuning with the VE table.

[brian617]

No not really.....You are basically adjusting your base pulse width (Displacement or Fuel Injector size) and fine tuning with the VE table.

If that is true then it seems you have miss calculated your injector PPH.

[Roadknee]

If that is true then it seems you have miss calculated your injector PPH.
I don't see it that way. The engine with better heads, cam, exhaust, etc. is capable of greater than 100% VE. The VE table can not accept over 100% VE. By reducing the injector constant the ECM increases the pulse width and delivers the needed fuel. I suppose we could accomplish the same thing by setting PE AFR at a richer then desired value (say 12.0 to achive 12.5) or something like that.

[brian617]

I don't see it that way. The engine with better heads, cam, exhaust, etc. is capable of greater than 100% VE. The VE table can not accept over 100% VE. By reducing the injector constant the ECM increases the pulse width and delivers the needed fuel. I suppose we could accomplish the same thing by setting PE AFR at a richer then desired value (say 12.0 to achive 12.5) or something like that.

See now you just proved that you miss calculated you PPH. How can VE be greater than 100%? Are there any VE tables than extend beyond 100% VE OEM or aftermarket?

[BLG355]

The VE table will not accept a number over 100. With a modified engine like yours you have to reduce the injector constant so that VE values under 100 give the engine enough fuel. If you reduce the injector constant and want fueling to remain the same, you have to reduce the VE table by the exact same percentage. Reducing your constant from 86 to 76 would be a 12 percent change. I think you'd run a little rich. Try 79. I think your engine will be happier.

Flipping the air cleaner lid increases airflow a lot. On 355chev's 1995 k1500 it increased manifold pressure from 85 kpa to 90 kpa at 5,200 rpm. The hypertech salad bowl was worth another 1 kpa.

I was curious how it would run and I set it to 79 and gave it a whirl, here is the log.

BLG

[BLG355]

Finally, with the larger TB you'll want to bump of the values in the line pressure tables to compensate for the added torque your engine will make at less throttle.

I'm not certain exactly which of these values should I increase?

8962

[Roadknee]

I was curious how it would run and I set it to 79 and gave it a whirl, here is the log.

BLG

That's better. The VE table could use some tweaking, but it's close. WOT is better, but started to lean out some in the top of second gear. Great second gear chirp BTW. How did it feel? Turn over the air cleaner lid and try it again.

[Roadknee]

I'm not certain exactly which of these values should I increase?

8962

Its the two added line pressure vs tps tables, 0-64 and 64-128 mph. I know you need more due to the engine making more torque at lower throttle settings with the larger TB, but not sure how much.

[Roadknee]

See now you just proved that you miss calculated you PPH. How can VE be greater than 100%? Are there any VE tables than extend beyond 100% VE OEM or aftermarket?

Geez Brian, I proved no such thing. You can research if you're truly interested in learning how naturally aspirated engines can achieve greater than 100% VE. I can give you a real-world example though. I was on the engine building team in the early 1990's for the owner of a 1963 Studebaker Avanti that wanted to be the first to go 200 mph at Bonneville with a Studebaker powered Studebaker. We built a 304 v8 with a ton of headwork, big solid roller cam, tuned headers and adapted a SB mopar vic jr intake and Holley 4 bbl. That engine made 450 hp at 7,500 rpm naturally aspirated on the dyno. The carb was outfitted with one of those turbine hats that accurately measured airflow. That engine achieved 114% volumetric efficiency. Once we bolted on the Paxton supercharger it made 638 hp at 7,250 rpm. Of course the VE with the supercharger was much greater.

BTW, he achieved his goal reaching 200.426 mph in September 1993.

[brian617]

I'm missing something then. I assumed that 100% VE was each engines particular ability to move the maximum about of air volume for its given combination of parts. 100% being the most air that engine could pump regardless of the actual volume of air. If that's wrong please explain.

[Roadknee]

I'm missing something then. I assumed that 100% VE was each engines particular ability to move the maximum about of air volume for its given combination of parts. 100% being the most air that engine could pump regardless of the actual volume of air. If that's wrong please explain.

VE is the ratio of the amount of air an engine actually passes divided by its displacement. A 4-cycle engine fills and empties its cylinder(s) once every two revolutions. If a 350 CI engine passes 350 CI of air every two revolutions it is achieving 100% VE if it only passes 315 CI it is achieving 90% VE. 385 CI is 110% VE.

[steveo]

100% volumetric efficiency is an engine taking in its full cylinder's displacement of air each intake stroke.

it's very rare and very difficult to achieve. most engines dont exceed 100%. that studebaker engine with 114% VE is a pure race engine that is tuned to the max.

exceeding VE is an air velocity kind of thing. scavenging, valve timing, intake charge resonance, bunch of crazy stuff combined have to happen.

if you DO exceed 100% VE, unless it's a really hardcore engine, it's usually like 101% or 102%, and a 1-2% error in the VE table is probably no big deal anyway...?

[Roadknee]

and a 1-2% error in the VE table is probably no big deal anyway...?

Agreed. Certainly is not a big deal to me. I have a really good tune in my truck right now. I could double the cylinder displacement and half the VE tables and it would run the same. Both would be very wrong, but the engine would run the same. I could half the VE tables and the injector constant and the engine would run the same. Point here is I don't really care (nor does the engine) if those values are accurate or not. I am only concerned if in the end of its calculation the ECM determines the injector pulse width that delivers the correct amount of fuel to the engine.

[steveo]

also worthy of note that its going to be at -rediculously- high MAP and RPM that it happens. generally you're in power enrichment at that point anyway. since you have a fuel modifier that is multiplying against VE or whatever, you can just make up the difference there.

[brian617]

Now that I understand VE completely and that 100% VE is hard to achieve, anything over 100% is really hard to achieve, why are you cheating the table? It really seems no different to me than increasing fuel pressure, with out changing the VE table or am I still missing something?

[Roadknee]

also worthy of note that its going to be at -rediculously- high MAP and RPM that it happens. generally you're in power enrichment at that point anyway. since you have a fuel modifier that is multiplying against VE or whatever, you can just make up the difference there.

High MAP, yes, but peak VE occurs around peak torque rpm, not peak HP rpm. Agreed you can use the fuel modifier to deliver the necessary fuel; comes down to personal preference.

[Roadknee]

Now that I understand VE completely and that 100% VE is hard to achieve, anything over 100% is really hard to achieve, why are you cheating the table? It really seems no different to me than increasing fuel pressure, with out changing the VE table or am I still missing something?

Let's say we want 12.5:1 WOT AFR. Our injectors flow-tested 84 lb/hr at 22 psi. We're running 22 psi and set injector constant to 84. VE table is in good shape with BLM's mostly around 128. VE table values in many of the 90+ MAP cells are maxed out at 99 or 100 (note: this is not necessarily the true VE of the engine, but what we have extrapolated from lower cells with BLM data as what will be necessary to achieve stoich AFR). We set PE AFR to 12.5. We install a wideband and go for a WOT run and our AFR is, say, 13.2 instead of 12.5. We need more fuel. The VE table won't accept higher values. Four options are available to deliver the required fuel to the engine : (1) increase fuel pressure and retune VE tables, (2) decrease injector constant and VE table values by same percentage, (3) decrease target PE AFR to something less than 12.5, and (4) increase cylinder volume and decrease VE table values by the same percentage. What method you use to provide the engine the required fuel is a matter of personal preference.

[brian617]

Let's say we want 12.5:1 WOT AFR. Our injectors flow-tested 84 lb/hr at 22 psi. We're running 22 psi and set injector constant to 84. VE table is in good shape with BLM's mostly around 128. VE table values in many of the 90+ MAP cells are maxed out at 99 or 100 (note: this is not necessarily the true VE of the engine, but what we have extrapolated from lower cells with BLM data as what will be necessary to achieve stoich AFR). We set PE AFR to 12.5. We install a wideband and go for a WOT run and our AFR is, say, 13.2 instead of 12.5. We need more fuel. The VE table won't accept higher values. Four options are available to deliver the required fuel to the engine : (1) increase fuel pressure and retune VE tables, (2) decrease injector constant and VE table values by same percentage, (3) decrease target PE AFR to something less than 12.5, and (4) increase cylinder volume and decrease VE table values by the same percentage. What method you use to provide the engine the required fuel is a matter of personal preference.

If your VE table is maxed out and you cannot achieve commanded AFR then you have in affect miscalculated PPH or miscalculated your engines fuel requirement. When you change the injector constant you are as I said earlier robbing Peter to pay Paul. In my opinion increasing fuel pressure is the logical approach. At some point fudging injector constant will only help until your injectors go static. I noticed in Barry's log even after you changed the constant the DC% was still pretty high.

[BLG355]

Does the injector constant change anything with the AE vs TPS and AE vs MAP adjustments? I'm going to post my bin, if anyone wants to criticize it, please do! :thumbsup: The only settings I have changes since I changed to the 7.4 TB has been the fuel table and the injector constant. Everything else before was working wonderful, or at least as wonderful as it can until I make a change and realize just how it wasn't as great as I thought it was lol. I've only been messing with tuning EFI for the past year, and it has only been on one vehicle. So I am open to all input from anyone who wants to offer any. I love learning and being around people who are great at teaching, one of the reasons I love this board.

BLG

[Roadknee]

Does the injector constant change anything with the AE vs TPS and AE vs MAP adjustments? I'm going to post my bin, if anyone wants to criticize it, please do! :thumbsup: The only settings I have changes since I changed to the 7.4 TB has been the fuel table and the injector constant. Everything else before was working wonderful, or at least as wonderful as it can until I make a change and realize just how it wasn't as great as I thought it was lol. I've only been messing with tuning EFI for the past year, and it has only been on one vehicle. So I am open to all input from anyone who wants to offer any. I love learning and being around people who are great at teaching, one of the reasons I love this board.

BLG

It won't. those tables just add to the pulse width. I think your Bin looks really good, which isn't surprising given that Eaglemark originally set it up :) VE table could use some fine-tuning. Try to collect some high MAP (80-90 kpa) BLM data. You either have to find a long hill, or be willing to apply a little pressure to the brakes while going down the road.

I am really surprised the 454 TB doesn't need more TPS AE. I didn't see any major lean areas in the log after throttle tip-in.

What are the build specs for your trans? I ask because the shift pressure profiling in the Bin is all factory original, and the 1-2 shift of your trans looks pretty firm in the log.

[BLG355]

It won't. those tables just add to the pulse width. I think your Bin looks really good, which isn't surprising given that Eaglemark originally set it up :) VE table could use some fine-tuning. Try to collect some high MAP (80-90 kpa) BLM data. You either have to find a long hill, or be willing to apply a little pressure to the brakes while going down the road.

I am really surprised the 454 TB doesn't need more TPS AE. I didn't see any major lean areas in the log after throttle tip-in.

What are the build specs for your trans? I ask because the shift pressure profiling in the Bin is all factory original, and the 1-2 shift of your trans looks pretty firm in the log.

I actually have all the AE backed way off vs factory settings, even from where mark had them too. It would stumble when cold when hitting the throttle and between shifts, so I back the TPS AE off a little, lowered the AE vs TPS vs Temp and lowered the 20kpa amount. I messed with it a lot based on feel. If it felt good, I'd go a little more until it felt off again then back it up again.

The trans has some goodies in it. I upgraded to a 13 vane pump, stock was ten. The valve body has a trans-go shift kit and their modified separator plate, also installed the .500" boost valve in pump. I made dowels on the lathe to lock the 3-4 accumulator in place, all accumulator pistons replaced with aluminum ones. I used the Sonnax Smart Shell due to the fact that this has rear planetary bearing value, which that addresses. It has a new GM reverse input drum and I used the Red Eagle Wide Power Band, replaced all bushings, bearings, and seals. I also upgraded to the corvette servo. I am happy with it overall. It does have a 3-2 downshift issue, it seems to bind/slip or a second before kicking down. until I get time to dig into it, I avoid 3-2 downshifts or do it manually, which then it is fine. I recently (6 months ago) got a 454 from a 98 pickup, rod bearing bad, but he sold the good 4L80e 4wd trans with it for $300. I grabbed a TBI intake from a junk yard cause it was $15, not intending on using it, but I have it now. But the trans I want to swap the 4L60e out for the 4L80e, eventually. I see some people are doing the swap, until I get extra time or the 4L60e breaks again, I'm just going to keep running it.

BLG

[Fast355]

I noticed the same thing bringing in timing earlier on the Vortec head engines I have tuned.

http://i243.photobucket.com/albums/ff172/Fast355_album/attachment-2_zps75x1guko.jpeg

All this mention of injector size vs VE tables has brought forth a personal opinon. It really does not matter where the pulsewidth comes from controlling the injectors as long as it holds the injectors at a reasonable duty cycle and the engine is getting the fuel it needs. I ended up lying the PCM in my Express van after adding in the 85mm MAF. With the smaller 3.5" MAF it would read closer to 300 GMS/SEC airflow. I also had VE tables that were reaching the 120-130% range. That much airflow put the cylinder air gms/cyl readings in the 0411 nearer the bottem of the scale, retarded the ignition timing and cause the 4L80E to turn into a race car transmission. When I swapped to the larger MAF I simply lied to the PCM that the injectors were smaller and then made tweaks to the MAF table to get the fueling where I wanted it. Works well for me, the MAF reads in the stock 200-240 gms/sec range and the VE table now tops out at 100-102% and the transmission shifts much more smoothly. Also on a side note the timing map I am running that I posted above is still working great. A newish 5.3 Tahoe that was dualed out was not having it when I was trying to pass him coming back from the shop last night while datalogging. I gave it WOT at about 75 mph, was passing him by the time I hit 3rd at 90 MPH and by the time I let off the throttle he was seeing nothing but Express van tailights. 27* of timing in the 5.7 pulling against a lock conveter in 3rd gear and ZERO knock.

http://i243.photobucket.com/albums/ff172/Fast355_album/20150503_213612_zps0gtatdlr.jpg