Jump to content
SAU Community

Recommended Posts

1 hour ago, Dose Pipe Sutututu said:

From what I gather I should just bin the whole fuel pumps running on PWM and just have them full noise with a massive fuel cooler to manage heat.

No, I have no problem with PWMing the pump. It's just the PWM motor controllers usually use big transistors as the switching units, without the optocouplers and other shenanigans that go into making an SSR. SSRs are black boxes,  but they shouldn't just be treated as black boxes when you push them outside of their design intent.

Fuel Lab, etc, pump controllers would just be a normal MOSFET switched PWM circuit. I'm sure you could find something workable on the net with some searching. You don't need a PWM circuit that generates it's own pulses and has a pot or anything else to adjust the PW. You only need the back half of the circuit that takes the pulses into the input of the big switch and lets the angry pixies flow. The main difference is that the PWM input and the main switched circuit end up having to share some things (like, at the very least, the earth side, I'm guessing) because the circuit would not be completely decoupled the way that and SSR does for you.

i gave this a shot with an SSR, and aborted. WHen you put a scope on the output it makes no sense, and the shape is wrong. weird buzzing that shouldnt happen and just generally misbehaving. 

as mentioned the proper way to do it is with MOSFETS, which i have not done yet. 

ok, just watched it, 12v 30 amps max.    which makes sense now that  i read the title as 3000W. so ok for a Walbro bro. turns out i have already bought one so i will see how shit it is or isnt in real life. 

was planning on just using a switched output to control pump either flat out, or PWM'ing. 

Great info guys - I might buy a moderately cheap oscilloscope to actually see what's happening. Great if someone wants to donate me a lab grade one I used at uni (I did a whole semester of introduction to electrical engineering for fun as an elective, I was the only student from IT) lol

The car has gone through 3x tanks of fuel so far, and the SSRs haven't died yet - but let's see, if they do then I'll fast track the mosfet idea.

42 minutes ago, Ben C34 said:

i have already bought one so i will see how shit it is or isnt in real life.

Are you saying that you've bought one of these motor controllers? Keep in mind what I posted to Johnny. The control input to those controllers is a potentiometer, controlling the pulse widthe coming out of the onboard pulse generator. You don't need that part of it. You need the PWM output from the ECU to drive the output stage of the motor controller directly. If they don't provide you with an easy way to interface with that (and disable the onboard pulse generator) you're going to have trouble using it.

46 minutes ago, GTSBoy said:

Are you saying that you've bought one of these motor controllers? Keep in mind what I posted to Johnny. The control input to those controllers is a potentiometer, controlling the pulse widthe coming out of the onboard pulse generator. You don't need that part of it. You need the PWM output from the ECU to drive the output stage of the motor controller directly. If they don't provide you with an easy way to interface with that (and disable the onboard pulse generator) you're going to have trouble using it.

Yep. One of them.

I wasnt particularly clear before, however I think I will just use a 2 stage setup with a switched output commanding full speed , so the rough idea is figure out where I want the pot set for enough fuel for general use, then replace pot with resistor. Output from ecu to short out resistor for full speed.

 

1 hour ago, GTSBoy said:

What sort of heatsinking do you have on the SSR? It should be bolted to something reasonably big and steel/alloy just based on what the datasheet says.

At the moment none, but I do have the correct heatsinks for them sitting on a shelf, just need a way to fit it all nicely (which hasn't been done, heatsinks were bought as an after thought).

Funny enough, they don't get too hot.

WIP photo (old) but you get the idea.

IMG-20180803-WA0015.thumb.jpg.fd30fb1480ca4b75c88e8535f36da7bc.jpg

 

MOSFETs are great and perfectly acceptable in an automotive environment - if properly protected. The gates must be protected against transient spikes. A few tens of volts can be all it takes to destroy the oxide layer and short the device. Unfortunately cars are terrible with transient spikes. So you'll have to trust that whatever device youre using has been designed by an automotive minded electrical engineer.

Not to mention that high currents controlled by PWM are probably going to create transients of their own. Those kinds of MOSFET controllers are going to switch hard and create a lot of high frequency transients.

I'd be cautious about those devices which are probably just someone's side project - which isn't intended to be a slight, but creating a rugged device for automotive use is going to take a lot of testing.

20 minutes ago, zoomzoom said:

MOSFETs are great and perfectly acceptable in an automotive environment - if properly protected. The gates must be protected against transient spikes. A few tens of volts can be all it takes to destroy the oxide layer and short the device. Unfortunately cars are terrible with transient spikes. So you'll have to trust that whatever device youre using has been designed by an automotive minded electrical engineer.

Not to mention that high currents controlled by PWM are probably going to create transients of their own. Those kinds of MOSFET controllers are going to switch hard and create a lot of high frequency transients.

I'd be cautious about those devices which are probably just someone's side project - which isn't intended to be a slight, but creating a rugged device for automotive use is going to take a lot of testing.

agreed. Which is pretty much why I have not installed it yet.

I would prefer to try out a fan controller from a VF commodore (or heaps of other options). They pwm the cooling fans so must be capable of a fair bit of current.

I'll start hunting for one of them again.... 

Actually this looks like the go.

Chinese versions available, 600w mentioned somewhere. No special plugs required cos you can chop off the existing plugs . Google this part number people  8K0959501G

 

Before everyone jumps on a train that they can't get off, has anyone actually measured the heat changes in the fuel at the tank?

I'd be interested in quantifying just how much heat we are talking about?  What pump type? And under what conditions?

Maybe what is needed for a dedicated track car isn't necessary for a road going version?

I didn't see this data anywhere in the thread BTW.  

 

I log fuel data, comes from the flex sensor.

Driving around the streets for about 45 minutes brings up the temps to about 35 degrees. Considering the outside air was about 18 degrees (data inside the Temp, Pressure, Fuel) table.

I suspect this will climb quite quickly on the track.

Mind you, the pumps are running on PWM and duty set quite low off boost.

To prove a point, I'll set both pumps to full noise and see what temps we get.

image.thumb.png.975c0044d6f0b4eb1c0b8dfe0ab3dd6e.png

 

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



  • Similar Content

  • Latest Posts

    • I'm looking for some real world experiences/feed back from anyone who has personally ran a EFR7670 with a 1.05 exhaust housing or a .83 I'm leaning towards the .83 because its a street car used mostly for spirited driving in the canyons roads. I"m not looking for big numbers on paper. I want a responsive powerband that will be very linear to 8000 rpm. I dont mind if power remains somewhat flat but dont want power to drop off on top. The turbo I've purchased is a 1.05, although the mounting flange T3 vs T4 and internal vs external waste gates are different on both housings, I not concern about swapping parts or making fabrication mods to get what I want. Based on some of the research I've done with chat gpt, the 1.05 housing seems to be the way to go with slightly more lag and future proofing for more mods but recommends .83 for best response/street car setup. AI doesn't have the same emotions as real people driving a GTR so I think you guys will be able to give me better feed back 😀   
    • Surely somebody has one in VIC. Have you asked at any shops?  Is this the yearly inspection or did you get a canary?
    • This is where I share pain with you, @Duncan. The move to change so many cooling system pieces to plastic is a killer! Plastic end tanks and a few plastic hose flanges on my car's fail after so little time.  Curious about the need for a bigger rad, is that just for long sessions in the summer or because the car generally needs more cooling?
    • So, that is it! It is a pretty expensive process with the ATF costing 50-100 per 5 litres, and a mechanic will probably charge plenty because they don't want to do it. Still, considering how dirty my fluid was at 120,000klm I think it would be worth doing more like every 80,000 to keep the trans happy, they are very expensive to replace. The job is not that hard if you have the specialist tools so you can save a bit of money and do it yourself!
    • OK, onto filling. So I don't really have any pics, but will describe the process as best I can. The USDM workshop manual also covers it from TM-285 onwards. First, make sure the drain plug (17mm) is snug. Not too tight yet because it is coming off again. Note it does have a copper washer that you could replace or anneal (heat up with a blow torch) to seal nicely. Remove the fill plug, which has an inhex (I think it was 6mm but didn't check). Then, screw in the fill fitting, making sure it has a suitable o-ring (mine came without but I think it is meant to be supplied). It is important that you only screw it in hand tight. I didn't get a good pic of it, but the fill plug leads to a tube about 70mm long inside the transmission. This sets the factory level for fluid in the trans (above the join line for the pan!) and will take about 3l to fill. You then need to connect your fluid pump to the fitting via a hose, and pump in whatever amount of fluid you removed (maybe 3 litres, in my case 7 litres). If you put in more than 3l, it will spill out when you remove the fitting, so do quickly and with a drain pan underneath. Once you have pumped in the required amount of clean ATF, you start the engine and run it for 3 minutes to let the fluid circulate. Don't run it longer and if possible check the fluid temp is under 40oC (Ecutek shows Auto Trans Fluid temp now, or you could use an infrared temp gun on the bottom of the pan). The manual stresses the bit about fluid temperature because it expands when hot an might result in an underfil. So from here, the factory manual says to do the "spill and fill" again, and I did. That is, put an oil pan under the drain plug and undo it with a 17mm spanner, then watch your expensive fluid fall back out again, you should get about 3 litres.  Then, put the drain plug back in, pump 3 litres back in through the fill plug with the fitting and pump, disconnect the fill fitting and replace the fill plug, start the car and run for another 3 minutes (making sure the temp is still under 40oC). The manual then asks for a 3rd "spill and fill" just like above. I also did that and so had put 13l in by now.  This time they want you to keep the engine running and run the transmission through R and D (I hope the wheels are still off the ground!) for a while, and allow the trans temp to get to 40oC, then engine off. Finally, back under the car and undo the fill plug to let the overfill drain out; it will stop running when fluid is at the top of the levelling tube. According to the factory, that is job done! Post that, I reconnected the fill fitting and pumped in an extra 0.5l. AMS says 1.5l overfill is safe, but I started with less to see how it goes, I will add another 1.0 litres later if I'm still not happy with the hot shifts.
×
×
  • Create New...