I've been doing a good bit of research on the EOIT tables....

Not trying to start a long thread, just wanted to get an idea of what you guys do when programming a car with an overlap cam.

Do you use true EVC, a little before EVC, middle between EVC and IVO, or what is your methodology?

 

I have a 234/242/.600/.615 117+2 cam in my 418. I delayed the EOIT by 25* and that stopped the black soot from forming on the rear of my car. Also the exhaust tips stay clean now, and improved my fuel mileage. Just a slight gain in the driveabilty, as it is very nice with only 4* valve overlap. Also slightly less exhaust smell, but I do have high flow cats.

I just kept delaying the EOIT by 10* at a time until my fuel trims stopped going anymore negative, then backed off 5*.

Russ Kemp

 

I went with 50* delayed in the normal table then slowly backed it back up to the OEM settings based on RPM. At low RPMs I advance it back 10* (so it's only delayed 40*) and by the higher RPMs I advance it back around 40* (so it's only delayed 10*).

I had to do this because it drove like crap with a straight 50* delayed and at higher RPMs I was getting insanely lean with them delayed that much.

Helped fuel economy some but most of all it eliminated most of the raw fuel smell at idle.

 

Ok, sounds like you have a Gen IV vehicle. As the Gen III's don't have an RPM axis for the EOIT tables.

Russ Kemp

 

Correct Russ... But I follow you. I was looking at the way they did it in the newer vehicles too. Would be nice if I had the RPM table.

 

I think going by the HP Tuner's forum I went with Russ K's method. He mentioned it there too. So my final value I've been working with is 6.25. Or a 0.7 shift.

I just dug up my cam box from the closet and found cam specs. I guestimated when playing with the excel spreadsheet and didn't trust it but I might be able to work with it now.

I know off hand I have a 115+2 235/238 0.620/0.615 cam LSL lobes.

 

So you delayed your EOIT by 63*. Sounds a bit late to me. Did you try less delay?

Russ Kemp

 

Ahhhh.... So Russ is one of the guys I was reading in that 20+ page forum. I read that thing all the way through. Good stuff!


I'm currently at 40degrees delayed or 6.0 (if my math is correct). Running muuuuch better.

Cam is Comp #: 64-459-11
281LR HR-113

@ .050 231/239 .617 .624 113 LSA 109 ICL

 

I tried a 5.85 value initially. When I did the spreadsheets, I ended up with 6.22 which is not too far off. New normal 5.69 and true normal was 6.22.

With regards to driveability, there was no difference in feel from the 2, but my gut says the 5.85 "felt" much improved over stock.

As far as "smell" out the exhaust. I'm having a hard time detecting any fuel smell except for cold start in morning. When I say detect, I have to do a double take to be sure I actually did smell fuel. TBH, the 5.85 had more detectable fuel smell during warm up than the 6.25 setting.

So my options are 5.85 which is just 0.3 off stock, 6.25 current or readjust to 6.22.


When I plugged in 00Vette04GTO's cam specs, I got a New normal of 5.67 and true normal of 6.26.

Attached are the 2 files. I used the cam math file to get the values used to input into the EIOT worksheet.

 

I personally went for a middle ground between new normal and true normal. Didn't want to go too far. I am going to keep playing with it and see what kind of differences I notice. Gas smell is virtually gone, and idle is much more stable.

 

I also noticed our cam profiles are very similar.

 

 

Just an update. Since I have my cam details from the box, I plugged in the numbers and ended with EVC at 6.22. I decided to try 6.20. My thoughts on this is that I have 6.5 degrees of overlap 0.1 = 8 degrees 0.02 = 1.6 degrees where the spray will occurring. The exhaust should still be evacuating the cylinder BUT the intake will be barely open enough for the injector spray to travel through. I'm hoping this would make for a better "mix" for air/fuel.

The result of the quick test for groceries seemed to concur with that. The engine got smoother to almost a "purr". Some quick data logs showed no real difference in the LTFTs, but the butt dyno along with the wife agree that the engine felt smoother, part throttle, cruise, idle etc.

-edit:
Data logging seemed to indicate much richer in this situation meaning I'm probably using up the fuel much more efficiently. I'm not even getting a hint of fuel smell once warmed up.

-edit 2:
new thoughts: The spreadsheet says I have 6.5 degrees of overlap. The EIOT controls when the next pulse shold happen. 6.22 for me indicates when the exhaust valve has closed, but the intake has been open for 6.5 degrees. So knowing 6.25 was a bit rough and with the intake being open for 8.5 degrees already at that point with that setting, I went 6.2 which means the intake was only open for 3.7 degrees which made for an even nicer smoothness.

So based on the spreadsheet, I have the IVO occurring at 6.15 and the EVC occuring at 6.22. If I put the delay to 6.22, that means the spray starts occurring while the intake is open already for 6.5 degrees and the exhaust is closed. Result should be no raw fuel going out the exhaust. The bad news is, I'm not spraying on the closed intake which can affect atomization. So in theory, if I delay it less to say when the intake valve is definitely closed ie 6.15 or less, say 6.14, I get the "closed" intake valve effect like stock. The injector pulse will be subjected to TDC and the ivo occuring at 6.15, the cylinder will pull in exhaust and intake charge as the exhaust is high pressure and will force itself back into the cylinder a bit before the exhaust valve is closed and the only source is the intake valve.

It's a bit to imagine here but my dilemma is this: which will work better start spraying on a closed intake valve for more atomization BUT take the chance that some of it goes through reversion and then sucked out the exhaust? Do I absolutely wait for the exhaust to close then spray. The 6.25 test seems to be rougher indicating that a fully closed exhaust valve and partially open intake did not atomize as well and gave a bit of roughness to it.

I'm doing a long 400 mile drive today and will log 6.15 to see if a)the butt dyno and wife concur that it got even smoother (and hopefully improved mileage).

 

Been following your thread and I decided to give this a whirl. My calculated values came out to 5.88 and 6.55 so I split it and went 6.22

The car sounds different at idle. Something I can't quite put my finger on, but almost sounds like you can hear the cam lope a little more.

Throttle response off idle seems noticeably more crisp. Hoping it's not just placebo effect. Didn't get to test as much as I wanted as I had a brake proportioning valve failure and lost nearly all brakes in process of my drive. (brand new brass valve...been on the car maybe 6 months)

 

The two spreadsheets I provided work hand in hand. If you have the cam card with valve timing events, then enter those in to get your proper duration/lobe separation/overlap etc

If you have your 0.050 timing events, ie most basic cam info eg 230/239 111 0.550/0.560 etc use those values to get the necessary values needed for the cam math sheet.

In the cam math sheet, choose LS1/LS6 base (its on the right side for the 2 values) and modify the first part, add in your values obtained from the other sheet and it should give a proper new normal EIOT.

I found the EIOT of the IVC event is the best to use for me. It starts firing on a closed intake valve and may have reversion due to exhaust overlap which helps mixing. If using the exhaust closed values, it runs rougher as the spray occurs x number of degrees (depends on overlap) into the intake opening meaning you are getting spray into cylinder. Earlier still has it firing on an closed intake which may cause pooling of fuel which either way, doesn't mix well (smells rich out the pipes and famous for that rich smelling lope).

On another note, with the EIOT setup right on mine, I now have a LEAN condition at idle, ie it smells BAD out the exhaust. Reminds me of my early modding days on my SBC where without tuning, you ended up leaning up badly and exhaust to make your eyes burn. This made for tough times passing the sniffer as nOX was always high.

 

I am unsure which spreadsheet I found. I have the cam information and used it to calculate. The spreadsheet I used has the cam event calculator and the EIOT calculator on the same page

I only changed the one table in the tune (99 pcm) and did not touch anything else.

My car has always read lean at idle on the wideband and that didn't change. My fuel trims are still very close to what they were as well.

 

Look up a few posts and you'll see I've provided both spread sheets in a ZIP file.

I used the cam math sheet to determine IVO and EVC.

If you have cam card, can put in your events IVO IVC EVO EVC etc to determine Intake/Exhaust LSA Advance.

If you have those 4 values already (most cam boxes), then can input it directly to determine those 2 numbers, IVO and EVC.

Take the 2 values to the EOIT sheet and use as new EVC and new IVO and choose the base cam profile of LS1 cam or LS6 cam and put those into EVC and IVO.

The new normal and true normals can now be determined correctly.

 

We chose the magic stick 3 camshaft for my new 408 Tx Speed stroker. After reading about all the EOIT information on the internet and studying the books I have on tuning, it appears to me that the "Boundary" should be set approx. 22 degrees earlier than stock because of how much earlier the inlet valve opens than stock, and that the "Target" needs to be set approx. 22 degrees later than stock because of how much later the exhaust valve closes than stock. To accomplish the latter, I must increase Target by a total of 44 degrees to make up for the amount the Boundary was reduced plus the additional 22 degrees of delay from stock setting. These changes are obtained in HP tuners by subtracting 0.25 reference periods from the stock Boundary setting and adding 0.500 reference periods to the stock Target settings. Narrowing the injection "window" on both ends, which is what this will do, makes a lot more sense for a performance camshaft with valves opening sooner and closing later than stock than what I've seen in most other posts. I will have my car running around the middle of next week and will let you know how this works.

 

So I've read all this... and used the spreadsheet. Ended up with a True EOIT of 362 for EVC and 356.6 IVO for my new cam... it's calling for 6.23 and 6.17... what would I put into my boundary and normal? Leave boundary at 6.5 and put 6.2 into Normal? Across the board?

What about makeup?

 

makeup should match normal, just copy-paste. I haven't messed with EOIT for a while so I forgot all the math but the boundary value and normal value should add up to whatever degree you want EOIT at. I vaguely remember adjusting my EOIT by around 45 degrees and had boundary at 6.73 and normal at 6.77. You can set your normal up to be uniform across the board but the idea behind earlier EOIT's at cooler temps is to give the fuel more time to sit on the hot valve while the engine is cold, so up to you. It looks like you want to spray onto an open valve anyway.