Re: Please comment on dyno tuning strategy (holley guys?)
[Re: radar]
#1693883
11/03/14 08:47 PM
11/03/14 08:47 PM
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Joined: Feb 2010
Posts: 1,645
Phila. Pa.
Mattax
top fuel
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top fuel
Joined: Feb 2010
Posts: 1,645
Phila. Pa.
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Hey Radar, Sounds like a good deal. I'll put my suggestions in-line. I've certainly had my share of attempting to maximize dyno time. Quote:
I'm thinking I will get on the rollers and warm up, then ballpark the four corner idle on the wideband.
I would do this, best you can, beforehand. Work with a vac gage/MAP and best in gear with least rpm drop (assuming 727 trans). If there's time at the end of the session, check and tweak but save that shop time for the dyno.
Quote:
Next will be trying to simulate a low throttle 35mph cruise on the T-slots. If it is close I will try idle air bleeds to sharpen it up, if not then work with the IFRs first. Once that's done the idle corners and curb idle rpm can get finalized.
Study up on what a Mustang Dyno can do. What I've seen with eddy currents is that you can apply constant load, apply a stepwise load, or tell it to hold a constant speed. I'm just not sure the holding a slow speed can be done with all - do check beforehand. The problems I've had with the idle circuit too lean have been when adding gentle throttle, like when going up hill, not steady state. Again my suggestion is to do what you can in a parking lot or on the street. My recollection is that you have an Innovate WBO2 logger?
Quote:
Next on to the primaries- I'm not sure if I'll try and put slack in the throttle to just open the front 1/2 of the carb? I know a 60mph cruise is solidly into the primaries. Anyway, my PVCRs are not currently adjustable so I figure I should see how much richer the power valve gets it then jet for a compromize between best power with PV open and leanest clean cruise with the PV closed.
NO SLACK. Set the throttle cable up so you are sure that when you put your foot down, the throttle blades are fully open. You'll feel stupid if you do WOT and later realize the carb wasn't at WOT...don't ask me how I know...
Different approaches here, which may be dictated by the dyno and instrumentation available. Personally I like to start with the WOT runs. In part because steady state at 60 and even 70 mph can always be checked on the highway.
My suggestion: Run the secondaries disconnected. Then look at the AFR and see how flat it is. From that decide if the MAB may need adjusting. If so, make another run or two after trying adjustment. Then adjust primary jets if needed. Run again. Remember fuel distribution won't be quite the same as when running with secondaries. Keep it a little on the fat side.
Next, reconnect the secondaries and do the same as above except on the secondaries.
All that done, go back and see how lean (primary main jets) the car will run at 60 and 70 mph. If you're doing this on the dyno, put a little load on it to simulatte wind resistance and hills. If the the car will run without surging at 70 mph using leaner main jets than WOT, then you can think about the PVCR. In the meantime, the safe thing to do will be run the best jetting for WOT.
Quote:
My acc. pumps have smallish nozzles and pink? cams in them from my last 408 combo- the old airgap certainly needed less fuel so I'll probably have to go bigger. I have a complete set of jets and air bleeds and pump cams but only a handful of random squirters. Is this even something worth messing with on the dyno? Seems like I might be better off doing the pump shot last- I always did it seat of the pants until there was no hesitation.
I don't think you can do serious pump shot tuning on a dyno. They always want you to roll into the throttle. Your old method is still a good method.
Quote:
I am planning on leaning on the experience of others with the timing. I'm thinking my current setup should be safe on high test pump gas. I am planning to try going to 36° total to see if I get more power. Does it make sense to take for granted that 34° is close enough to do the AFR tuning first, then try a little distributor twisting? It's 10.2:1 CR with basically stock edelbrock chambers and .040" quench.
If you have time to do this, I'd go the other way to start just to be safe. In other words, run it at 34*, then try 32* and see if you lose anything. Then decide if it makes sense to try more timing.
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Re: Please comment on dyno tuning strategy (holley guys?)
[Re: radar]
#1693886
11/03/14 10:39 PM
11/03/14 10:39 PM
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Joined: Jan 2003
Posts: 12,133
Benton, IL.
DaveRS23
Special needs idiot
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Special needs idiot
Joined: Jan 2003
Posts: 12,133
Benton, IL.
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I like a lot of what Mattax suggested. Start with setting the timing and the WOT. Does your carb cruise at 50+ MPH on the mains or the idle? If it cruises on the mains, I would go easy leaning the slots. It could cause a slight stumble at tip in. Although the DPs are very rich on the street.
I also agree that it would be best to deal with the cruise on the street. But if your LM-1 is on the fritz.................
Master, again and still
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Re: Please comment on dyno tuning strategy (holley guys?)
[Re: DaveRS23]
#1693887
11/04/14 01:20 AM
11/04/14 01:20 AM
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Joined: Feb 2010
Posts: 1,645
Phila. Pa.
Mattax
top fuel
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top fuel
Joined: Feb 2010
Posts: 1,645
Phila. Pa.
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If you can get the LM1 working, especially with RPM, it's a great tool. Try the full recalibration. One time, I don't remember why, but I had to reload the firmware. Another time a battery change solved whatever it was. Here's a couple of screen shots from an dyno day to years ago. As you can see the Innovate's response was rapid. No question that the primary side had a pretty flat AFR for the pull, and the secondary needed work with the bleeds and high speed bleed. However, it doesn't show power or torque. Best you can do is compare slope of rpm. The dynojet's WBO2 in the tailpipe was very damped or slower responding. On the other hand, effects on power and torque can be read at any mph or rpm. So this is also useful. Also notice that some of the pulls show all three gears (727) and others only 3rd gear. With a stick car, I think the dyno owner will prefer you get it into either 3rd or 4th early. Chirping tires on the rollers is probably not a good thing!  
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Re: Please comment on dyno tuning strategy (holley guys?)
[Re: Mattax]
#1693888
11/04/14 12:28 PM
11/04/14 12:28 PM
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Joined: Jan 2003
Posts: 12,133
Benton, IL.
DaveRS23
Special needs idiot
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Special needs idiot
Joined: Jan 2003
Posts: 12,133
Benton, IL.
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These graphs from Mattax show how important it is to be able to log and graph AFR and RPM. It unlocks the real potential of the wide bands. The wide bands that do not have this ability are very limited. Having a passenger monitor the guage, or videoing it, or trying to watch it while pulling through the gears is barely functional. And not real safe. Unless there is already a datalog system on the car, the only widebands that should be considered for tuning, should have logging and graphing incorporated. 
Master, again and still
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Re: Please comment on dyno tuning strategy (holley guys?)
[Re: DaveRS23]
#1693889
11/04/14 04:38 PM
11/04/14 04:38 PM
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Joined: May 2006
Posts: 1,260
New Mexico
Adobedude
pro stock
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pro stock
Joined: May 2006
Posts: 1,260
New Mexico
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I have a Daytona Sensors WB with a digital read out, I use my GoPro to record a run.
It get's everything during a pass:
Air Fuel reading
RPMS
Shift point
Oil Pressure
Fuel Pressure
Time slip tells me everything else.
2001 Dodge Dakota
408 All Motor
11.27 @ 117.83 mph
2017 NM Mopar Challenge Series Champion.
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Re: Please comment on dyno tuning strategy (holley guys?)
[Re: Adobedude]
#1693890
11/04/14 09:51 PM
11/04/14 09:51 PM
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Joined: Jan 2003
Posts: 12,133
Benton, IL.
DaveRS23
Special needs idiot
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Special needs idiot
Joined: Jan 2003
Posts: 12,133
Benton, IL.
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Can you post what a pull or pass looks like using that method? Your version may be better than the ones I have seen. It would need to be because the ones I have seen were not nearly as useful as the logs and graphs displayed above.
Master, again and still
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Re: Please comment on dyno tuning strategy (holley guys?)
[Re: radar]
#1693892
11/05/14 12:51 PM
11/05/14 12:51 PM
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Joined: Jan 2003
Posts: 12,133
Benton, IL.
DaveRS23
Special needs idiot
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Special needs idiot
Joined: Jan 2003
Posts: 12,133
Benton, IL.
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Do you or the dyno guy happen to have any of the quickest opening power valves handy? The 9.5 or 10.5 PVs are not something that a lot of guys have laying around. But I have found that when I get the cruise clean (mid to upper 14s usually), the engine needs the PVCR flow quicker to prevent a stumble as the throttle is lightly or slowly opened more.
Enjoy!
Master, again and still
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Re: Please comment on dyno tuning strategy (holley guys?)
[Re: Thumperdart]
#1693894
11/05/14 02:26 PM
11/05/14 02:26 PM
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Joined: Feb 2010
Posts: 1,645
Phila. Pa.
Mattax
top fuel
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top fuel
Joined: Feb 2010
Posts: 1,645
Phila. Pa.
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A good strategy for when a powervalve needs to open is outlined by Urich and Fisher Holley Carburators and Manifolds, at least the older editions. It was written for tuning for oval, road and autocross racing, but the concepts apply. The underlying concept is that the power valve needs to open when the load is gets high enough that the engine needs enrichment. They test for the engine's needs by crowding manifold vacuum down to power valve opening point.
As their book was written in the late 70s, they of course did it with a stop watch on a closed circuit. But with todays eddy current dynos and consumer priced dataloggers, its possible to rework the strategy for these new tools.
Basically the idea is to start at a moderate load and speed, say 35 mph, and add enough throttle to drop the manifold vacuum to 14 in hg, and hold that vacuum while the car accelerates. Then do this again 2" lower, and again 2" lower down to power valve opening. Shrinker wrote that with a g-gas, the proper PV opening point is revailed by the change in combustion seen on a 5-gas. Since most of us don't have access to a 5-gas, we just have to look for where performance starts to drop off and while trying different jetting and PV opening points.
Let's say we're testing on an open road rather than a dyno. The car accelerates lightly when crowded to 16", 14" and acclerates a little more when crowded to 12" but kind of goes flat at 10" and 8". Below 8" the power valve opens and the car takes off like you expect. Next, we install slightly larger main jets and it accelerates about the same, but the rpms and g meter show that crowding 16" it's a little lazy from 50 mph up. Based on that, the next test would be to go back to the original jetting trying a 9.5 and 10.5 power valve.
Opening too early is a bit harder to identify. It should be a little slower on acceleration, but its tricky maintaining and repeating part throttle acceleration once the PV opens.
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Re: Please comment on dyno tuning strategy (holley guys?)
[Re: Mattax]
#1693895
11/06/14 12:33 AM
11/06/14 12:33 AM
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Joined: Jul 2007
Posts: 1,682
Philadelphia
radar
OP
top fuel
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OP
top fuel
Joined: Jul 2007
Posts: 1,682
Philadelphia
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So like I said I love geeking out on the finer points- how big of a straw to have sticking up into my tin can etc. unfortunately today was a bust. I have the worst luck with chassis dynos- last time my car drove up on the wheels my fuel pump crapped the bed as soon as I was all tied down and ready. I had to push it down and come back a few days later to throw a fuel pump on it.
This time it wasn't enough to have all my tools and tuning items carefully packed, oil changed, valves run. I had modest goals and thought I was ready, but nope murphy came into play like always. We plugged the dyno's WB into my bung just past the collector and got started. I set the idle to 13 just for starters and went to get a baseline on my T-slot cruise AFR, doing 35 in 2nd gear, making like 15hp according to the dyno.
All the sudden the AFR went dead lean, 19.x, and stayed there. Dyno op said either exhaust gasket is beat and sucking air, or a misfire is shooting raw fuel.
I grabbed a laser thermometer and started getting readings off the header tubes (TTI double ceramic). 330, 180, 330, 345, wait- 180°? I shut her down and pulled the plug and it was slightly damp with fuel.
Ugh. Cyls 3 & 4 were cooler and misfiring. I sprayed them with ether, blew them dry, and tried again, this time laying off the acc. pump before cranking. It did the same thing.
It's just a normal setback but I had 1yr old firecore wires, the analog msd 6aL and pro billet distributor and blaster II coil, and new autolite 3924 plugs.
I usually feed my edelbrock heads champ rc12yc so I'll try that first, followed by swapping wires, then coil, then detailing the distributor (they get oxidized), then a new ign. box, then if that doesn't work I'm gonna set the car on fire and push it into the river.
Anyway if you read this far you have a high tolerance for complaining. I drove the car to the body shop where they have my hood- I need a week off from tuning. Hopefully I will come back fresh and organized. It's funny- driving there from the dyno the car felt pretty strong- no pinging, good power. I was beating on it a tiny bit to try and get the rings seated. I had to hop out and raise the idle from 900 to 1100 so it didn't load up and want to die at stops, but I don't think I'm gonna be too far out of tune when I get the ign sorted.
So thats how dyno day went (didn't go). Now back to discussing proper PV opening and PVCR sizing- my 2¢ is that cars should have personality and there's more than one way to skin that cat based on driving style and drivetrain setup.
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Re: Please comment on dyno tuning strategy (holley guys?)
[Re: radar]
#1693896
11/06/14 12:33 PM
11/06/14 12:33 PM
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Joined: Jan 2003
Posts: 12,133
Benton, IL.
DaveRS23
Special needs idiot
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Special needs idiot
Joined: Jan 2003
Posts: 12,133
Benton, IL.
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Now might be a good time to line out the LM-1.
Master, again and still
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Re: Please comment on dyno tuning strategy (holley guys?)
[Re: Thumperdart]
#1693898
11/07/14 02:36 AM
11/07/14 02:36 AM
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Joined: Jul 2007
Posts: 1,682
Philadelphia
radar
OP
top fuel
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OP
top fuel
Joined: Jul 2007
Posts: 1,682
Philadelphia
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This setup is my old frankenstein 750- It's got an original style 750 HP main body, a stock 750 DP base plate and metering blocks, and original style 950 HP float bowls.
I didn't take notes on the setup since it's been on the new motor- the metering blocks are stock 750 double pumper replacements from holley. They have the low IFR location with .014" wires in them. The emulsion package is unknown non adjustable and the car's not here. I never tried the two hole setup that is often reccommended but I didn't have problems with slugging or richening with rpm on my old 408. The bleeds are adjustable but I don't have any notes here.
What are you thinking?
Last edited by radar; 11/07/14 10:35 AM.
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