620 Land Speed Record

[G-Duax]

12 hours ago, distributorguy said:

I'm also going to build a larger vacuum chamber to stabilize the signal from the manifolds to the MAP. 

 

Been toying with the idea of doing this for my bike carbs for the signal going to my distributor.

Not happy with the idea of coming off a single runner for the vacuum source, with the pulses beating my vacuum advance all to hell at low speeds.

 

Good luck with the MegaDribble, as we call it in the Toyota community.

I know some people like them, but many find that they are lacking for high output engines.

[distributorguy]

My friend who is tuning the truck has been tuning MS since they came out, and has successfully tuned dozens of 700+ hp rally cars.  They aren't lacking anything but a simple user interface.  The steep learning curve is the biggest problem - which isn't that steep for IT guys apparently?  

 

The reason we have to use a large plenum (and I finally built it yesterday) is that the vac signal was bouncing from 40-80 kpa at idle.  7" of vacuum at idle caused by a split pattern 306-318 duration cam.  I'd be happy to get it stable within 10 kpa.  

[distributorguy]

While waiting for our tuner to get home from vacation, I managed to wire up the headlights, brake lights, and turn signals so we can go street tuning once we get current license tabs or collector plates and a turn signal/hazard switch that'll be delivered Tuesday.  I'll ziptie a rear view mirror in place since the cage is blocking the factory mount.  With the new exhaust system installed we're relatively quiet.  Almost legal.  

[datzenmike]

Many California models use a small restriction in the emissions vacuum lines to slightly delay or smooth out transient signals to the vacuum advance. Would that work? 

[Stoffregen Motorsports]

A pressure snubber can be used to smooth out the reading, but there may be a delay, and tuning around that delay would be futile.

[distributorguy]

Apparently the delay issue is a myth.  I've even proven it in houses - doing blower door test pulling a vacuum on a house to see how well sealed it is.  The entire interior of a home - from the basement corner to the upstairs storage room - no matter if its 3000 or 10,000 sq ft  will equalize in pressure simultaneously.  A small vacuum tract in an engine works the same way.  I essentially have a  10" long 1" copper tube with 2 vac fittings off the manifold pulling vacuum on it, then it dees through a 1/4" line to the MAP where a pill with a .040" hole gives the signal to the sensor.  I've use a "pill" in the MAP line over the years on a few projects and it works very well.  Given that we rarely will show any vacuum, this will just help us tune the long pull in 3rd and 4th gear.  

 

 

[Stoffregen Motorsports]

So you don't care if there's a delay between the reading and the actual vacuum? You just need a steady reading? for your software to do its job? That makes sense.

 

BTW - I may be sending you another Lucas distributor. My hotrod Sprite that I just reacquired after nearly 20 years is in need of some work. Once I pull the motor, I'll send it your way.

[datzenmike]

7 hours ago, distributorguy said:

Apparently the delay issue is a myth.  I've even proven it in houses - doing blower door test pulling a vacuum on a house to see how well sealed it is.  The entire interior of a home - from the basement corner to the upstairs storage room - no matter if its 3000 or 10,000 sq ft  will equalize in pressure simultaneously.  A small vacuum tract in an engine works the same way.  I essentially have a  10" long 1" copper tube with 2 vac fittings off the manifold pulling vacuum on it, then it dees through a 1/4" line to the MAP where a pill with a .040" hole gives the signal to the sensor.  I've use a "pill" in the MAP line over the years on a few projects and it works very well.  Given that we rarely will show any vacuum, this will just help us tune the long pull in 3rd and 4th gear.  

 

 

 

 A home will equalize quickly because BIG doors to let air in or out.

 

 Pressure takes time to fill a container through a small opening, so will vacuum. Can't be instant, it has to obey the laws of physics. 0.040" may be like a large door, make the hole smaller.

[distributorguy]

18 hours ago, Stoffregen Motorsports said:

So you don't care if there's a delay between the reading and the actual vacuum? You just need a steady reading? for your software to do its job? That makes sense.

 

BTW - I may be sending you another Lucas distributor. My hotrod Sprite that I just reacquired after nearly 20 years is in need of some work. Once I pull the motor, I'll send it your way.

What is the delay for a vacuum signal?  You can actually enter that delay time into the software to tune with it, but we can't verify ANY delay, and we're only using MAP to resolve altitude changes as well as low rpm use (well under 4k) so we don't have a dead spot in acceleration off the line.  The ITB (independent throttle body) setting then switches from MAP to TPS as the main input.  So yes, we can live with a small delay from the MAP as its just a minor band-aid for a driver who doesn't understand how the EFI works.  

Does that make more sense?  

 

Mike, the house equalizes the moment you turn the blower door fan on or off, peel the seal off a bath fan, etc...  Its not about opening the front door, although if you compare volume displacement, the entire house still equalizes even if you pull the seal off the sump pump pipe.  A 2" hole in a 72,000 cu. ft. box.  I think the comparison is fair to a MAP sensor on an engine running 10 cu. in. of vacuum stored in a pipe, released through a .040" hole.  If you do the math, its actually identical.  Gotta follow the math. 

 

All of this is moot anyway.  The tuning issue we've been battling turned out to be a failed NGK Racing spark plug.  Proven by a quick test of EGTs, verified while re-testing the coil packs, replaced.  Cold starts have been a challenge to tune, due to all the ceramics reflecting heat in the combustion chamber.  Basically we had to treat the engine like it was stone cold until we got up to 185 degrees block and coolant temp.  Our cold start fuel map looks like a cliff Wile E. Coyote falls off of instead of a typical modest ramp.  

The Cam signal is now fixed - 100%. 

The MAP "system" is now giving a nice stable signal via table-top highs and lows across 10 kpa which it averages to the exact center point and it further improves with rpm until we can remove it from the equation under about 2" of vacuum.  

Edited July 23, 2019 by distributorguy

[datzenmike]

I thought the complaint was vacuum  'spikes' from only 1 or 2 sources. I was saying that a restriction would slow the spike down just like a muffler removes exhaust spikes. Maybe 'delay' is the wrong word. 'Softening'? 'Averaging? 

 

The vacuum advance delay (usually on California models) is a sintered bronze 'restriction' and a valve in line to the distributor. Some 720s have small color coded restrictions in their emissions hoses.

[distributorguy]

The MAP spikes (raw data) are indicative of any engine running far more than 12:1 compression at low rpm.  Massive velocity to zero velocity, repetitively.  Just put your hand over the tailpipe and imagine an exaggerated version of that pulse in the intake.  The goal is to find the "middle ground" simply to find a place where the fuel mixture will be close at low rpm - a single digit vacuum number to tune by.  Our power band is 4500-9600, with decent torque above 3k (meaning better than 100 ft lbs.)  The fact that we can run a 13.5:1 engine smoothly at 450 rpm (if we chose to do so) says the signal is now adequate.  I wish I could post a  lay-over of the two graphs from the "stock" signal versus when we damped it so it made more sense.  In either case MS was calculating the mixture influence via the average of all signals.  Any delay we introduced is no longer than the time  between the peak and the drop, which is not going to affect our top speed.  We simply "put glasses on" the computer so it could focus.  Compare all this to the DCOEs' metering, and you'll soon realize we're light years ahead of last year's tune.  Think there's any time delay in "metering" pushing an accelerator pump squirt through the jets and into the intake?  It must have been at least 25x slower than the MAP processing time.  Hell, we use 9 different tables to tune mixture just for engine warm up and idle.  Anytone who says MS is an inferior product simply hasn't worked with it long enough to understand it.  The big difference between this and AEM or others is that there's very little customer support, unless you know the right people to call.  Its complicated, but effective.  When you have a problem with other brands, they sell you a fix, then charge you for time to help.  Many of their "fixes" don't even work, then you end up with software glitches from poorly made circuit boards from companies like FAST, and their tuning algorithms suck.   I can't tell you how many times I've seen a FAST erase its tune after 3 hours of dyno tuning.  Just enough to run away and not look back, the same way I'll never buy and install another Pertronix branded product.  

 

The vacuum advance "delay" actually increase signal response time in many applications to prevent pinging under light acceleration and high vacuum, but that's a band-aid to overcome poor timing required to pass emissions so it has NOTHING to do with what I'm doing.  Again, if you could see how we altered an insane "shark tooth" graph and turned it into mild plateaus, You'd nod, smile, and understand with 2 thumbs up.  

[Stoffregen Motorsports]

3 hours ago, datzenmike said:

I thought the complaint was vacuum  'spikes' from only 1 or 2 sources. I was saying that a restriction would slow the spike down just like a muffler removes exhaust spikes. Maybe 'delay' is the wrong word. 'Softening'? 'Averaging?

That's what I thought you were talking about too.

 

[distributorguy]

I Guess I could have described it better.  The goal was for the computer to see a cleaner signal, and not have to average such a horrifically wide sweep, which it was handling ok but there was certainly concern that it may not be as precise as possible.  Normally a MAP reads from a plenum in the intake manifold, so I just made my own plenum to make up for very short individual intake runners, mimicking a more traditional intake manifold signal.  

Most of you may not have worked with or remember Dodge's issue with MAP sensors back in the early 90's (think minivan origins).   They failed frequently because they were mounted in the engine bay, a couple inches from the intake, with no filtering.  Their repair was to use a longer hose with a "filter" in the hose to reduce the erratic signal and also to keep potential fuel out of the sensor.  I've simply taken this to a higher level due to a wilder signal.  

 

On a brighter note, by the end of the day we'll be "street legal" and potentially start road tuning.  

[Stoffregen Motorsports]

Jeff, have you seen the article about the idiots trashing the salt?

 

Here - http://www.fourwheeler.com/news/utah-residents-rip-bonneville-salt-crust/?wc_mid=4035:17119&wc_rid=4035:1252945&_wcsid=BDDFFF5F6AD58170191AC4A6233ABDB97C7EDA32DBBFEA23

[BrothersGarage]

8 hours ago, Stoffregen Motorsports said:

Jeff, have you seen the article about the idiots trashing the salt?

 

Here - http://www.fourwheeler.com/news/utah-residents-rip-bonneville-salt-crust/?wc_mid=4035:17119&wc_rid=4035:1252945&_wcsid=BDDFFF5F6AD58170191AC4A6233ABDB97C7EDA32DBBFEA23

What a bunch of fuckwits!

[datzenmike]

The world is full of them. We've been them too. Who hasn't?

[distributorguy]

On 7/24/2019 at 7:09 AM, distributorguy said:

20 hours ago, Stoffregen Motorsports said:

Jeff, have you seen the article about the idiots trashing the salt?

 

Here - http://www.fourwheeler.com/news/utah-residents-rip-bonneville-salt-crust/?wc_mid=4035:17119&wc_rid=4035:1252945&_wcsid=BDDFFF5F6AD58170191AC4A6233ABDB97C7EDA32DBBFEA23

 

 

I knew about it before it was an "article."  They overlapped the end of the long courses around the 4 mile mark.  The truth is, the course area was still so wet as of last Sunday that they moved the long course to a location much further away from the highway.  Once the "powers that be" at BFG were made aware of their stupid video, they made a meager donation to the "save the Salt" organization, as if it'll earn forgiveness.  This was a corporate supported and posted film, not a few kids screwing around.  They didn't know it was on the salt flats or that it was illegal????  Ignorance is no excuse.  It just makes them look even worse.  

 

If you drive along the freeway past the flats, you'll see donut marks everywhere.  You'll also see deep ruts from those who got stuck and paid thousands $ to get pulled back out.  The lucky ones get out before they get ticketed.  

[Stoffregen Motorsports]

Many times I've been tempted to veer off the freeway onto that salt...

[distributorguy]

Who makes the best off-the-shelf starter for the L20b?  Our rebuilt unit is rebuilt very poorly and my spare is taking a beating.  Help!!!

[620slodat]

With that compression you should try a SD22 diesel starter. But, I don't know if you can find one on the shelf, or if it will fit since the starter is on the opposite side of the motor. Since it is made stronger for the high compression diesel it would be worth checking out to see if it will fit.

 

Don

[wayno]

Nope, the SD series starters are 9" long for the huge direct drive unit and 9.5" for the gear reduction unit, the L block only has 8" between the engine mount bracket and the transmission plate/transmission, there is not enough room for the diesel starter.

I also recall that the diesel flywheel has different teeth for the starter as I had a flywheel made for a diesel out of a Z24 flywheel and the starter ring had to be transferred from a SD22 diesel flywheel to the Z24 flywheel I had made to fit my SD25.

Edited July 26, 2019 by wayno

[datzenmike]

1 hour ago, distributorguy said:

Who makes the best off-the-shelf starter for the L20b?  Our rebuilt unit is rebuilt very poorly and my spare is taking a beating.  Help!!!

 

 

280zx or Maxima gear reduction starter.

 

 

Very snug fit up against the oil pressure sender. This is from a ZX so it will turn a hot L28 six cylinder no problem. Somewhere I have an '84 Maxima starter also.

[620slodat]

37 minutes ago, wayno said:

Nope, the SD series starters are 9" long for the huge direct drive unit and 9.5" for the gear reduction unit, the L block only has 8" between the engine mount bracket and the transmission plate/transmission, there is not enough room for the diesel starter.

I also recall that the diesel flywheel has different teeth for the starter as I had a flywheel made for a diesel out of a Z24 flywheel and the starter ring had to be transferred from a SD22 diesel flywheel to the Z24 flywheel I had made to fit my SD25.

 

Good info Wayno.

 

Don

[Stoffregen Motorsports]

x2 on the gear reduction starter. If you can find a donor, even in bad shape, you can bolt the adapter plate onto many V8 gear reduction starters sold at places like Summit or Jegs.

[distributorguy]

Cool - thanks guys.  Funny that you'd add gears to a direct drive starter, but I get it.  Ours has taken quite a beating.  Last night we finally found the source of our problems that I've not mentioned (no start.)  Something in our firmware decided that we shouldn't use sequential spark, that the truck would only run on Batch fire despite the cam and crank signals being perfectly clear and concise.  We'll work around this until we can Verify which signal is being improperly interpreted.