Romans 2005 Toyota Echo

[Spencer]

Yeah I think its just for clean/cold air, but the later 90's cars all seem to intake down from the bumper, making me wonder if the grill is just a bad spot for some reason. But then the later ones all have magic duct work up front also that they tie into.

Just a excuse to look at BTCC engine bays really /ling

[Hyperblade]

On 23/12/2022 at 16:57, Roman said:

I remember reading something from a BTCC guy who said they looked into ram air type setups and said there was no point. 
As in ideal conditions its only a millibar or two of extra pressure, at maximum speed. Then you lose that as soon as you are following someone else. 
 

I don't believe they didn't use it, you only have to look at the insanely complex carbon intakes across a wide range of touring cars that they created for many $$$ and look at how much $$$ they spent on the cars, your telling me they wouldn't have done it for say 5hp more? Agree running behind someone you lose the effect, but you don't want more hp when your at the front to stay in front? Doesn't compute in my brain. but i've been wrong before...

 

 

On 23/12/2022 at 17:17, Spencer said:

Yeah I think its just for clean/cold air, but the later 90's cars all seem to intake down from the bumper, making me wonder if the grill is just a bad spot for some reason. But then the later ones all have magic duct work up front also that they tie into.

Just a excuse to look at BTCC engine bays really /ling

 

You will get high pressure zone just above the splitter/spoiler where the air is hitting the air dam but with a trade off of potentially higher air temps (as closer to the track). If you think about the huge amount of work to duct the intake to that area, it must have been worth all the effort/$$$ in performance to get to that high pressure.

This is a good article on it all from Willem Toet (F1)

https://www.linkedin.com/pulse/air-ducts-down-earth-guide-motorsport-applications-willem-toet

[Roman]

Alright consider me sold on the subject!
Will be something interesting to test. 
Especially since I've got your differential pressure gauge to test things with. 
Then I can hook up a MAP sensor into the airbox as well. 

However I'll need to try figure out what is actually going to be physically possible to acheive. Maybe I will use my other bonnet before I cut it for other reasons, and make a little airbox inlet space.

 

[Roman]

Alright so rather than trying to make this fit in a cramped space and get a compromised result.
I'm gonna start with what I figure the ideal ram-air box would look like and I'll cut my spare bonnet around it.
Then see what difference there is in a best case scenario. 
Will hook up a map sensor into the base of the airbox to see what sort of pressure gains are possible.

Then if it works good, I'll try compare that best-case result to something that fits the car. 

So will have a base plate section that is 100mm radius around the throttles, and then 60mm long non tapered section (so this is high pressure zone) 
Then from here it's extruded with a 5 degree taper (may as well stay safely below maximum)

Then a bellmouth on the entrance to try make sure flow stays attached. 
This thing will be absolutely monstrous, haha. About 525mm long so I cant print it all as one piece. 
However if I make the angle 6 degrees or 7 degrees then maybe it will be fine.
The narrowest part of the slot has an area equivilent to an 80mm circle which is heaps. Could maybe go a little smaller.

However I've also just assumed that the airflow direction will be perpendicular to the throttles which it wont be. 
Will go measure what sort of angle there is.  then adjust it.

[Roman]

I went for a drive with the new radiator setup. 
I dont have the radiator fully blanked off, but generally the radiator stays around 35-45 degrees when cruising at 100kph with no fan going.

So doing some full throttle stuff, the engine temp still spiked even though radiator temp stays low. 
So that's interesting.
Maybe the flow through the thermostat is the current bottleneck. After all its designed for 75hp maximum and tootling around at half that.
I guess I can try take the thermostat out and see how it compares. 

The radiator temp did slowly creep up some time after a full throttle run, so ti will be a bit more punished with continous full throttle at a track day. 
But that's where finishing off the ducting will help. 

[Roman]

Here's an interesting one 

[shrike]

Remind me is this running an electric waterpump?

If so is it running a constant or varible flow rate based on criteria? What are the thermostat dimensions? Be interesting to see how it compwres to say a 4age one size wise.

What temp does the thermostat open at?

Edit: google says Japanese Prius Tech Manual says the thermostat specification is starting to open at 82C (180F) and fully open at 95C (203F)

Can always drill a couple of holes into the thermostat if need be right?

[Roman]

Yeah it's running an electric pump, turned on full speed all the time. 
When the thermostat is out, it pushes water around like crazy. 
I dont think the pump itself is the issue, they use the same part number pump on the bigger hybrid motors too. 

Hmmm if it does fully open only by 95 deg then maybe it's not so bad, as it only got to 96. 
Will need to drive it for longer to see if that number keeps going up, so long as it's not over 100 then it's probably fine. 

[VitesseEFI]

4 hours ago, Roman said:

Hmmm if it does fully open only by 95 deg then maybe it's not so bad, as it only got to 96. 
Will need to drive it for longer to see if that number keeps going up, so long as it's not over 100 then it's probably fine. 

This, more testing needed 

[deankdx]

6 hours ago, Roman said:

Yeah it's running an electric pump, turned on full speed all the time. 
When the thermostat is out, it pushes water around like crazy. 

is the water circulating through the radiator too quickly to cool? this was a problem on some cars (when thermostat removed) but i can't remember what type(probably ford V8s) 

[keltik]

10 hours ago, Roman said:

Hmmm if it does fully open only by 95 deg then maybe it's not so bad, as it only got to 96. 
Will need to drive it for longer to see if that number keeps going up, so long as it's not over 100 then it's probably fine. 

Retrofit one of those ghastly electrically heated thermostats so you can run a high temp for efficiency on the road then heat it to open early on the track.

Did Toyota run a thermostat with the electric water pumps?

[VitesseEFI]

Thought that one of the reasons for EWPs was so that you could vary their speed accordingly to heat loading?

[Roman]

Every single OEM EWP implementation that I've seen runs a thermostat. 
Maintaining circulation and pressure are especially if an engine has water jackets very close to the exhaust ports or whatever.
Can get localized boiling that then makes your measured engine temp do big see saws. 
Or just push all the coolant out of the overflow when it seems like nothing wrong.
I've never seen an EWP setup that didnt have headaches from trying to run without a thermostat. 
Waterpump and thermostat do two very different jobs.

So yeah it runs essentially the same way a mechanical pump engine does, except the pump speed is disassociated from engine speed.
I can vary the pump speed using a PWM signal, but this was causing my pumps to blow up, as when I switch the car off I think the ECU was backfeeding voltage through the pump.
If I reduce the pump speed the car could idle slightly lower from less alternator load but that was the only tangible benefit I found.

I dont think there's such a thing as water flowing too fast to cool.
If water travels twice as fast a in circuit it might only draw away half the heat each lap, but its doing two laps. 
But I think the issue is that a thermostat also acts to build pressure in the system even when its open, by being a partial restriction. So when you remove thermostat it doesnt get put under pressure.


 

[cletus]

When I was mucking around with cooling system issues one thing that helped was a better flowing pump. 

On their website it has a thing about the common train of thought that coolant flowing too fast means the radiator can't cool it down properly 

However slowing it down means it also spends more time in the hot bit, ie the engine

https://flowkoolerwaterpumps.com/pages/why-flowkooler-hi-flow-pumps-end-overheating

 

 

 

 

 

[Roman]

Started printing an airbox design. I decided that it's unlikely that I'll be happy testing just one iteration.

So made it a bit more modular with 2 pieces so I can swap the fronts. Or run it without the front piece on at all for comparison.
I had to add a 13 degree slope to make it parallel with airflow direction.
I think the angle is a bit too steep on the diverging part here for this theory to work to its potential.

People have said that 7 degrees is the magic number maximum for tapering out, but they havent mentioned whether thats in total or per wall. 
If it's 7 degrees total then 3.5 deg per wall is going to be difficult.

I wish I still had a good CFD program. I've been trying to learn OpenFoam but man what a headache!
 

[Roman]

Okay sooo 

I just found a 2d CFD program that uses an MSpaint bitmap and a text file to set parameters

Holy shit a brick I am going to absolutely pollute the internet with garbage now
 

 

[kpr]

wow.  

[tortron]

Ms paint combined with graphs at long last

[kws]

Just when you think this thread couldn't get better 

[h4nd]

On 27/12/2022 at 19:24, Roman said:

 ...so long as it's not over 100 then it's probably fine. 

Water at 15psi boils at 125C, not sure how far antifreeze pushes that?

Also, heat moves due to temperature difference just like fluid flow moves from pressure difference. Lots of coolant flow into a rad means a higher temp in the rad, so more temp diff to atmosphere, so larger overall heat flow into the cooling air (will heat the air more, with heat from the coolant, from the engine).