Megasquirt Support Forum (MSEXTRA)

R100RT wrote:Very nice workmanship on your manifold plumbing - I didn't notice if you mentioned what material spec you went with?
I prefer 321SS for high heat zones (Burns has good stock on mandrel bends most sizes & doesn't break the bank). As you most likely know, if using lighter gauge, lower grades can suffer from the dreaded "intergranular" corrosion issues and turning into fragments.
Looking forward to following your successes

Thanks!
Honestly, I'm not sure about the actual specs on the header material, I have been involved with the EFI and the electrics
Yes of course we are aware that turbo headers need thicker wall on the headers, ours are 0.1" wall

First turbo tests were done last weekend, my "random-fuel map" was very close, at least up to about 8PSI boost. No boost control on yet, let's get the mapping sorted first.

Lo-cost turbo intake duct


Ready for the National Champs season opener this coming weekend

Last week was the European Champs event along with the National Champs in Alastaro, Finland

Literally minutes before heading to the event we added the Turbo Staging feature. No SSR's controlling the transbrake solenoid, just simply the popular IRLZ44N FET. Worked just fine. Seems that the TB solenoid is not fast enough so we have to add a bit of linelocked brake to limit the bump. The first Turbo Staging settings were default 0.050 and 2 bumps. No difference when we changed to 0.035 and 1 bump. Both times did one giant leap from prestage to stage.

Anyway, run #7 (if I remember correct) with the new turbo setup netted a nice 7.621sec ET, keeping in mind the class limit of 7.600sec. Without any dyno time we were surprised how quickly we got a decent set up. And with only 1.2BAR boost on the 7.621sec run, about 0.2BAR lower than on a comparable run with the centrifugal supercharger from last year.

Here's a videoclip of the 7.6sec run and turbo staging : https://youtu.be/piIF7VA1zVY

Nice work, and great looking car/setup

Linelocked rear brake added to the turbo staging feature. Bump test video with about 600PSI of brake pressure. Yes the garage floor is slippery

https://cam67.1g.fi/kuvat/sometime+raci ... test_3.mp4

Can you soften up those bumps at all? Use smaller mini-steps and/or a faster solenoid?

James

jsmcortina wrote:Can you soften up those bumps at all? Use smaller mini-steps and/or a faster solenoid?

James

James,
This weekend is a drag racing event so we'll know for real how the linelocked brake helps those bumps. Currently the bump release time is 0.035 (# of moves 1) and we haven't tried a lower value yet. If a lower value doesn't help we have to look for a faster TB solenoid or maybe bump the solenoid voltage up to 16V...
Challenges for the bump (besides the TB solenoid) :
- Torque converter is already quite "tight" at launch rpm
- 531ci BBC at about 1bar launch boost has TORQUE...

I've not tried the bump personally yet, but I know others have used short mini-bumps to get a smoother effect.

If you have time in the workshop can you try smaller times?

http://www.msextra.com/forums/viewtopic ... 35#p365614

James

I'm running a Glide and have been to 4400 on a double dump billet brake. If I tickle the prestage beam, .025 will just light, then shut off the stage light, had to double bump at time. Went back to .035 for a solid state beam, but will still turn off on the rock motion. I too might try the linelock tied into the brake to calm it down some, or try like .020 and command two steps

If your solenoid is fast enough, then running a number of small steps should give smoother operation instead of a big jump.

James

Hey guys,
Last weekend's event was the first actual bump test with linelock and yes it calmed down the rocking motion.

Here are two clips, unfortunately not from the best angle :
https://cam67.1g.fi/kuvat/sometime+raci ... lock_1.mp4
https://cam67.1g.fi/kuvat/sometime+raci ... lock_2.mp4

- The Holley EFI users have done a bump system succesfully using a PWM output, a long thread is at : http://www.yellowbullet.com/forum/showt ... p?t=598342
- Some used a PWM output along with a timed output to pass through the PWM for a set amount of time
- The good thing with a PWM table is it can be set according to launch rpm (higher RPM --> higher PWM duty%) which makes bump distance more consistent at varying launch RPM

Maybe we'll try something similar next, a string of very short pulses, like 10pcs or so

Gathering from the forum thread, here are some PWM examples translated to TB ON/OFF times :
100Hz & 72% duty cycle = 0.0072s transbrake ON , 0.0028s transbrake OFF (released)
20Hz & 70% duty cycle = 0.035s transbrake ON , 0.015s transbrake OFF (released)
15Hz & 70% duty cycle = 0.046s transbrake ON , 0.02s transbrake OFF (released)

One guy uses 100Hz & 72% duty cycle = 0.0072s transbrake ON , 0.0028s transbrake OFF (released) for 0.12sec time, making the number of pulses 12

Here's a nice example of a smooth working system : https://www.youtube.com/watch?v=szgPA9XN2VQ

A much better bump test clip from yesterday : https://cam67.1g.fi/kuvat/sometime+raci ... test01.mp4

0.015sec release time / 0.060sec on time , 5 bumps

This weekend is a national drag racing event so we'll see how the bump behaves on track, but it's looking promising

So, the 2017 season is over. Had a bit of a mishap, last fridays first qualifying run netted a 7.491sec ET @ 292.45KPH (181.6MPH). New record but at the same time out of the race, went under the Pro Street class limit of 7.600secs. Sh*t. Leaned fuel maps worked better and with the hall trigger sensor swapped to a VR sensor, no trigger issues.

After the finals there was an exhibition-type nightrace, here's a 7.6sec run from that : https://cam67.1g.fi/kuvat/dragracing/20 ... race01.mp4

Nicely don't sir!

I'm at two short bumps and seems to do good for me. How did your multiple setup work?

nathaninwa wrote:Nicely don't sir!

I'm at two short bumps and seems to do good for me. How did your multiple setup work?

Thanks Nathan!
We went down to 2 bumps as well, it's ok. Could be better though. Planning to use an oscilloscope and a highspeed-camera to film the TB solenoid action to see the true response time from release to closed. Would give us an idea how fast the solenoid really closes and how much (or little) changing the release time really affects the total time from open to close.

Rear tires saying ouch (from last weekend) :

Some off-season updates :

- We did a boost control test about 3 weeks ago and left wondering why we didn't reach the boost target

- We know that the boost levels we are running at are not ideal for the big turbo, it's way outside the turbo's optimal range. We only need about 1.3-1.4bar boost to reach 7.5sec ETs and the turbo is most effective at around 2bar
- We realized that the exhaust backpressure is too high at modest boost levels, preventing the 3-port solenoid boost control from working well.
- Today we hooked up another 3-port solenoid, so we are running two 3-port solenoids, one to the wastegate top port and other to the bottom port.
We didn't have any 4-port solenoids at hand so two 3-ports sufficed for our tests.

- After a few transbrake tests we got a decent setup which held a nice accurate target boost of 1.5bar with a ~0.5bar wastegate spring. A bit more finetuning but in all dual solenoid control seems to work quite well after just a few tests. Yes, we did overshoot once to 2bar boost, it sounded nice
Boost spool up is a faster with this setup vs. single 3-port solenoid.
We can still make the spooling faster than on the video, we still had the delta quite high, starting the closed loop control way too soon.

Here's a dual solenoid boost test video. Target boost 1.5bar : https://cam67.1g.fi/kuvat/sometime+raci ... target.mp4

2018 Season opener was held last weekend, the team finished 1st

Traction issues, more boost control fine tuning and split two PG input shafts!

Bump is better but we still have to use linelocked rear brake to tame the bump.
Bump settings, release time = 0.005 , on time = 0.200

Here's a traction-challenged run, bump is @ 1:15 : https://fi-fi.facebook.com/anne.rajala. ... 347312682/

It's been awhile !!

This weird, limited COVID- season ended here just over a week ago, the team finished 2nd in the national championship
But more importantly, new driver got the hang of things very quickly and the Opel was running very constant 7.6sec ETs.
After all, the new driver is a kid in his early 20's used to drive a 9.5-10sec ET car.

As for the Megasquirt EFI, just a few additions to the previous setup :
- Gearbox reverse and band pressure logging (mainly to see the line pressures during transbrake)
- Gearbox oil temp logging

Here's a clip of the finals event with first two qualifying runs : https://www.youtube.com/watch?v=EL30Fi0GUDM

Take a look at this Opel omega b by a Toyota land cruiser 80 engine 4.5 l turbo R6 ! https://youtu.be/WTJQzwML5e8 This most powerful Opel in Kazakhstan!