408 small block mopar (similar architecture to 406 SB Chevy), 175-180 kPa (~10.5-11 psi) of boost on 93 pump gas, 10.5:1 or so CR. How far is too far on timing?

Graph and current timing table below. Wondering how much further we can push it.

You can see in the jagged light blue where I added 2-3 degrees in the (3000-6000, 118-140 kPa) range and the lighter green/darker yellows where I added 2 degrees in the (3750-5500, 161-168 kPa) range. This overall picked up 2 tenths and 3.5 MPH in the 1/8 mile.

Converter is very tight and doing no favors also.

steve you know how this works spark plug reading is key lol

quote:

Originally posted by rusty:
steve you know how this works spark plug reading is key lol

I sent a PM about a half hour ago to Magnethead stating the same.

2BKING

Air intake temp is a big factor. What are you seeing there?

is this a combo that would be 35-38* if it was NA?

To simplify this he is looking for a target max safe timing at 10lbs of boost with a ProCharger. His 408 10:1 compression Mopar would closely relate to a 23* head SBC. This is a drag-n-drive truck on 93 octane pump gas with Holley EFI

I provided my inputs in PM. The only thing I want to see is a picture of the spark plugs ground straps. It has been well over a year since I saw the last couple of plug pics. They had plenty of timing in them. The mark was around the bend, heading for the weld with heat 1-2 threads down.

IMO, the best thing you could do is show the plugs ground straps. Using pump gas, you have a very narrow tuning window.

2BKING

Yea he needs to put a new set in first, he said he cant remember how old they are other than they from way before his last 1200 mile drag n drive event

This is just a suggestion with the graphs you’re posting to make it easier to follow. First, zero the time table to launch. Second, place a curser at max rpm prior to shift or somewhere that has some relevance in your posting. When you place the cursor in the graph, it’ll generate a “marker” on the “table” in relationship to the cursor position.

Here's the most basic/generic rule of thumb for boost vs. timing. 1lb. = -1* of timing; this is from its baseline NA timing for peak power. This is a general rule of thumb.

My engine made peak power with 36* - 38* of total timing. I use 36* as a safety factor! That being said, my bracket tune makes a peak of 15lbs. of boost. My timing is at 18.7* at that level. According to the rule of thumb, I should be at 21*. I would not want to go there! I'm using 100 UL pump gas with a small amount of water/methanol injection in the blower inlet.

My hotter tune with the same boost, but with better fuel (VP MS109 UL). We are at 22* & need about another 2* - 4*, we'll creep up on it in 1* increments. This tune is a good bit quicker/faster than the bracket tune with the same boost. All we are doing is adding a better fuel, more fuel & more timing.

Pretty sure some of this was where Greg Kelley was going with his question.

2BKING

Bryan, do you maintain that 18.7 all the way down the track or does it fluctuate with the level of boost?

quote:

Originally posted by Big Steve:
Bryan, do you maintain that 18.7 all the way down the track or does it fluctuate with the level of boost?

That's my timing at peak boost.

Here's a data log overlay on the timing map from this past weekend. I was leaving around 4,200 instead of 3,400 with the bracket tune. It will give you an idea of boost vs. timing.

2BKING

Looks super conservative unless iats are sky high. I’m more familiar with LS turbos, but this combo should be even less sensitive. General rule of thumb for 93 octane is NA timing until 2 or 3 lbs then down to 14 degrees at 14 psi.

I like Brians posted Base Spark Table that displays MAP as PSIG not kPa. He also has the Overlay feature enabled in Data Log that displays the trace of the run.

To switch MAP from kPa to PSIG in the GCF select “Toolbox” , Preferences, Display MAP as PSIG. To enable Overlay feature, select “Datalog”, Activate Overlay.

quote:

Originally posted by markemark:
I like Brians posted Base Spark Table that displays MAP as PSIG not kPa. He also has the Overlay feature enabled in Data Log that displays the trace of the run.

To switch MAP from kPa to PSIG in the GCF select “Toolbox” , Preferences, Display MAP as PSIG. To enable Overlay feature, select “Datalog”, Activate Overlay.

Thanks M & M,

Most EFI people seem to talk using KPA. It just seemed natural for me to use PSGI. As you can see, I like the overlay feature to take a quick look or for a visual for Big Steve.

2BKING The best things I did with new combo was the ProCharger & the EFI. IMO, that's the best way to go; like peanut butter & jelly.

Here is the map that was in the truck for my last pass yesterday, with overlay and PSIG enabled.

28* on the footbrake, up to ~10* at the shift (10.4 psi), fallback to ~14.8 degrees, back up to ~10* at the trap (10.2 psi), then down to 40 degrees when I lifted.

On run graph, red is RPM, orange is timing, blue is boost.

This message has been edited. Last edited by: Magnethead,

I’m unsure how much one knows about Holley EFI DA so I’ll share this that may be of some help to the novice.

If you open a GCF and then select a DA, reduce the size of the DA so that you can see both the GCF and DA together. Select a channel in the DA by placing your cursor on the graph line. RPM is selected in the photo. At the top header of the DA it shows you the Present/ Min/ Max rpm Values of the selected channel DA. If this channel was MAP or Boost it’d show you this min/max information immediately without searching. When you start scrolling the cursor using the arrow key, you’ll see the marker in the GCF moving showing the position value as well.

quote:

Originally posted by markemark:
I’m unsure how much one knows about Holley EFI DA so I’ll share this that may be of some help to the novice.

If you open a GCF and then select a DA, reduce the size of the DA so that you can see both the GCF and DA together. Select a channel in the DA by placing your cursor on the graph line. RPM is selected in the photo. At the top header of the DA it shows you the Present/ Min/ Max rpm Values of the selected channel DA. If this channel was MAP or Boost it’d show you this min/max information immediately without searching. When you start scrolling the cursor using the arrow key, you’ll see the marker in the GCF moving showing the position value as well.

I knew about following the yellow dot and seeing min/max, but I didn't know about the green trace or how to convert the axis to PSIG - I'm still learning how to do all these things. That helps. I've been watching some of Devin Vanderhoof's videos, but some concepts like this haven't been greatly expanded upon.

Part of the contention here is also that most people are used to an MSD 6/7/8/GRID box, which is completely different from a Pro600, Holley, or pretty much any other COP/CNP system. Learning to manage Dwell, Autoignite, and cylinder pressure is a dance that the HVC2 coils are ignorant of since they run a single coil at 525 volts/low amps rather than 8 coils at 12 volts/8-10 amps. I recall a study somewhere saying that the D510C coils I have are comparable to a 20 amp magneto if driven hard, and the Holley Smart Coils/IGN1A are comparable to a 44 amp mag at any reasonable dwell value. Having that hot of a spark also means having less timing, at least from the research I've seen. Regardless, a mag or HVC2 fires 4 times per revolution, a COP/CNP fires once every other revolution. The extra 'off' time, ± dwell, creates a hotter spark.

I'm only running 3.5msec dwell with no ramp table, so I am on the mild-aggressive side. I see no need to run at 4.0, much less 4.5 or 5.0 .

I know the needle moves alot per combination, I'm just trying to find the line between maximum power and running into issues. As Bryan said, 93 has a very narrow window to work within. Corn is hard to find on Raceweek so it's not really an option, plus a lot of places only carry 91 instead of 93 for premium so I have to factor some safety margin for that situation.

This message has been edited. Last edited by: Magnethead,