Romans 2005 Toyota Echo

[Roman]

Tyre pressures made a big difference! 
All 4 were all near 40psi to start with (didnt check since Tyre man filled them up...)
So dropped both fronts to 32psi, then rear left at 32 as well but right rear left at 40psi. 
Now there's no sign of single wheel action, which is a relief because I didnt really want to have to muck around with any of that other stuff. 
So since I've now fixed the physical issue, time to try get some consistency with getting off the line.

It's annoying and very inconsistent to try and use a small throttle opening to try hold the engines RPM to where it's good to launch, and then try coordinate going to 100% throttle and letting clutch out appropriately. It's very easy to bog the motor or get on the gas too soon and launch from an RPM thats too high.
Especially when there's no tacho, haha.

So I have opted to use an igniition rev cut to hold the motor at a given rpm when it's not in gear. So this means I can just hold it at 100% throttle and it'll launch same way every time. So then it's easy to know if I have to go lower or higher on rpm.
So for example the rev limit will be 4000rpm when the car's stationary but then 7300rpm in any gear. 

So this is instantly a million times better.
But then there are other problems I've found with how I've set this up.

So a timeline of events is as follows / on the graph below:
1. Car is stationary, I mash throttle fully open (Blue line at top) 
2. The RPM rises to the set threshold, in this case 4200rpm.
3. It reaches and then exceeds this rpm, the ignition cut starts (light blue line) 
4. I've dumped the clutch out, so the rpm starts to drop. The ignition cut starts to taper off downwards.
5. The ignition cut has a set decay rate, which is why there's a slope downwards on it rather than straight to zero.
So the motor bogs down a bit as it's taking too long to restore full ignition.
You can see the RPM dropping away so the ignition cut starts pulling back.
6. Despite all of this going on, the speedo signal has proven to be quite useless until fairly late, it stays at zero, then jumps to 27kph.  
7. Then there's a further delay until gear detection has worked. (bottom line, shows gear now = 1) 

So its not great to be waiting for the gear detection to allow the full rpm limit.

The net result of current settings is that with a 4200rpm launch the motor bogs right back down to 2800rpm. Boo!



So the plans from here

1. Try find out why the Driven speed signal is useless at low speed. Currently the speedo signal goes from the gearbox to the dash, then dash sends signal to ECU. 
I suspect it might improve if I take the signal straight from the gearbox speed sensor.

2. Instead of a gear based rpm limit (I've got no need to have a different speed limit in any other gear) I'll change it to speed based, so at least there isnt the delay waiting for gear detection to work.

3. I will reduce the ignition cut decay rate to be way quicker. Currently set to 5% decay per 20ms but probably no reason not to set it to 100% 

Even with the above issues, it's now sitting somewhere around a 2.4 second 60 foot. Previous best was 2.55. So good improvement with more to go hopefully.

There's no point fine tuning all of this too much ahead of time, as the drag strip is a very different surface to roads.
But I'll be happy to have a good methodology to fine tune the launch rpm and decay rate on the day.
Time will tell how well it works / hopefully dont blow something up first haha.

Now that the traction is good maybe I'll try get a rear wheel speed source so I can just setup the traction control and launch control to just automagic the above stuff.
This car has ABS so it's got 4x wheel speed sensors coming into an ABS controller module, I'm not sure if it's possible to piggyback off this though. 
But it would be nice to have a front left and right wheel speed so I can tune the rear tyre pressure difference if one or the other starts to slip.
Will do some homework on it. 

Even without the fancier auto-magic launch control stuff, I think this method above is pretty good as there there are only two variables to contend with.
It's easy to see how well they are both working and adjust them. 

 

[ajg193]

How many launches do you reckon the box/shafts can take before it just gives up?

[Roman]

Probably keep on going until the clutch eventually gives up! Which is most likely scenario as this is still on the original one.

C series box is same-ish as used in the 2ZZ Celicas, 20V cars and so on. 

A 5000rpm launch is still not that much power in the scheme of things haha. 

Fingers crossed...

[thegreatestben]

C series was happy behind my 7agte. I think you’ll be fine 

[ajg193]

Hah, had no idea they kept making C series for so long

Looks like 1984-2007+

But yeah, they can take a good beating

[Roman]

Yeah I reckon! 

They probably got the most punishment in AW11s haha. And seem to put up with it well enough.

[Stu]

C series in my EP - seems to take the 11sec punishment fine.

[Truenotch]

I think the Echo C series is a bit different to the C52/C56 etc that's found in AW11s, AE82/92/101/111. Should still be plenty strong, but I think the final drive and diff are different to the others (which means you can't transplant an LSD from a C52/6). 

Still, Murray's supercharged 1NZ has never had an issue with the gearbox, so you'll be sweet. 

[AllTorque]

When I was at Toyota we fit a TRD LSD to a turbo Vitz. Same part as an Altezza.

[shrike]

Are spare gearboxes cheap? Could always weld the diff up :p

[Spencer]

59 minutes ago, AllTorque said:

When I was at Toyota we fit a TRD LSD to a turbo Vitz. Same part as an Altezza.

I had to look because I doubt the vitz has a 7.5" crown wheel like the Altezza? Interestingly the vitz LSD number matches the ones listed for AW11, AE92 etc

[thegreatestben]

Stock tezza lsd an option then?

[Spencer]

They are way different.

[AllTorque]

Well in my defence, the documents it came with were in Japanese.

[Roman]

It would be incredibly convenient if true! 
As I've got a few F series LSDs kicking around haha.
I guess the OD of the crownwheel doesnt necessarily have to be the same in order for the bolts on the diff to be compatible.
But seems unlikely / I think I've heard of other people swapping normal C series LSD in.

I found someone that swapped the 1NZFXE 13:1 1500cc prius motor into an AW11, then put the normal 1NZ cams in it. 
But then they used the shit house factory intake manifold with the tiny throttle and a standard Echo ECU.
Lame on both counts.

Made 109-110hp atw by 5700rpm but then factory rev limiter cuts the fun short.
So maybe some potential there with better intake and more revs.
They're $500 engines so would almost be rude not to at some point...

But it's amazing this works at all on a completely wrong ECU haha. Probably why its got such a wonky powerband. knock control is probably having a hernia.


 

[sheepers]

15 minutes ago, Roman said:

I've got a few F series LSDs kicking around haha.

wat.

 

got any 3.7/3.9 CW&P you dont want?

dont need the whole LSD, it would be nice, but at this point im just trying to find a lower F series ratio. 

[Spencer]

1 hour ago, Roman said:

It would be incredibly convenient if true! 
As I've got a few F series LSDs kicking around haha.
I guess the OD of the crownwheel doesnt necessarily have to be the same in order for the bolts on the diff to be compatible.
But seems unlikely / I think I've heard of other people swapping normal C series LSD in.
 

Yeah but the bolt patterns from memory are different like 10 bolts vs 6 bolts. Also FWD nuggets are wayyyyy shorter than RWD LSD's. Going on the TRD part numbers about 100 other C-series cars/models crosses over with the vitz part number so pretty good bet a C-series LSD works

[Roman]

1 hour ago, sheepers said:

wat.

 

got any 3.7/3.9 CW&P you dont want?

dont need the whole LSD, it would be nice, but at this point im just trying to find a lower F series ratio. 

Nah man theyre hard to find. Took years to find a 3.7 and we had to buy a whole car to get it.

Not sure if you can buy them new somehow.

[sheepers]

ah yip,

you can get them new, guess ill have to do that.

cheers anyway. 

[Spencer]

Off topic and @sheepers probably knows this but yeah looks like they are $1100->$1200 new

from old toymods post (would have to verify this yourself)

then on amayama 3.7 ratio is ~$1100. Part number crosses over with hilux which is what people always say but never seen anyone find one IRL and swap it.

https://www.amayama.com/en/part/toyota/4120129298

3.5 ratio slightly cheaper

https://www.amayama.com/en/part/toyota/4120139467