RomanDave's Prius C swap

[Neinris]

Wished this car was available in the US. I love how my 08 two door hatch looks, but this weighs 63lbs lighter. I wouldn't have to go on a diet when I decide to make mine a track car.

[CrankyOldMan]

Originally Posted by Neinris

Wished this car was available in the US. I love how my 08 two door hatch looks, but this weighs 63lbs lighter. I wouldn't have to go on a diet when I decide to make mine a track car.

You can import them from Canada into some states, MI is really easy. Or you can import RHD versions from Japan in a few years once they get out of the 25-year blackout period (they don't have FMVSS or EPA certification for North America).

[Neinris]

Originally Posted by CrankyOldMan

You can import them from Canada into some states, MI is really easy. Or you can import RHD versions from Japan in a few years once they get out of the 25-year blackout period (they don't have FMVSS or EPA certification for North America).

Sorry in advance for hijacking the topic... I've always loved the Vitz, even when I used to play Grand Tourismo on the PlayStation, I didn't care that my friends would laugh at me.

Yeah but it'd be in KPH... LOL! Not really a deal break. RHD is a no go for me, it'd be hard to drive on the CORRECT side of the road.

Not sure how much I'd have to pay through customs if I get one from Canada, any idea?

But back to the build... Kudos to the OP, your work inspires lots of us. Please post new dyno test after everything is completed.

[CrankyOldMan]

Originally Posted by Neinris

Not sure how much I'd have to pay through customs if I get one from Canada, any idea?

For Michigan, you just transfer the title at the Secretary of State and pay whatever applicable taxes/fees for the value of the vehicle. Not sure about customs though since I bought it from TheBarber (who is a Canadian National that lives in MI on a visa). Check with your state's rules for importing vehicles for more details, I guess. :)

[mitch9521]

I love this build so much.

[mitch9521]

I would love to swap my C50 for a C56, but getting one to Canada from Japan out of an NCP131 Vitz is north of 2 grand, the transmission itself is usually under $600 CAD, its the outrageous shipping that gets expensive very quickly.

[RomanDave]

Meanwhile in New Zealand an RS model NCP91 had its C56 sit there at a DIY wrecker yard until the car got crushed... because I procrastinated too long to get it out!

One thing I noticed is that the shifter linkage arrangement and the engine mount positions are different on the later boxes (compared to my model)

The benefit is that it gives much much much better clearance for the exhaust and shifter cables.

A turbo swap would be a tight squeeze with an NCP13 box, if I was trying it with a half decent sized turbo I'd probably try make the NCP91 box work.

[CrankyOldMan]

RomanDave has earned a skill point! (Gearboxes +1)

Awesome work, glad to see a fellow gearhead working with the gears. Looks like you did the bell housing split instead of pulling off 5th gear?

[RomanDave]

Yeah thats right.

It was a bit tricky, but on the whole not bad - I'd do it that way again.

If the box needs new synchros or something, then I'd do it the other way of course.

But just for LSD install I figured this makes sense.

[RomanDave]

I got the LSD fitted, and it's made an awesome difference!

This gearbox is much less clunky than the other one.
Still a bit stiff sometimes, but not too bad.

Still working on how I want the engine bay to look, currently black trumpets and purple engine cover.

DSC08485.jpg

The trumpet length has been good, but they only juuuussssttt touch the edge of the bonnet. Which is actually fine, I could file them slightly to fit.

But ultimately I want an airbox over them for longevity.

So started on some new trumpets with more of a bend.

new trumps.jpg

Then started on an airbox, printed a 2D section for starters then looked to see where it would hit things. Used some plasticine to find the areas where clearance was poor.

245346808_1229235190913416_5855725064962605128_n (1).jpg

Then started on a revised model, and currently printing it.

245139379_430336005435662_7673741119578456079_n (1).jpg

Ready for printing:

245336092_2743819892583446_688116223703235922_n.jpg

Artists impression to help visualize it:

dsfgtjtyku.jpg

Once the shape looks good I'll need to figure out how to split the shape up into bits so I can still get inside to do up the trumpets. Then what sort of filter to use, and its exact position.
Then start making some thin printed parts which I will carbon wrap.

It's cool making 100% carbon parts, but, it's considerably more work for only very small weight savings. Using 3d printing to get the geometry correct, then using carbon for strength is a very quick and easy process. (comparatively)

[mitch9521]

Love it

[RomanDave]

Airbox has been progressing nicely, latest revision fits a pod filter on.

DSC08534.jpg

Then wrapped in carbon for strength.

247169007_854553755207464_3616752159736919023_n.jpg

I'm still working on the lid part, but happy with it!

Also ordered some maxspeeding rods, and will try get a set of the 13:1 pistons so I can get VVTI working.

So I can hopefully rev to 9k with a bit more safety margin than factory rods.

[Flipper_1938]

Originally Posted by RomanDave

Airbox has been progressing nicely, latest revision fits a pod filter on.

Attachment 61997

Then wrapped in carbon for strength.

Attachment 61996

I'm still working on the lid part, but happy with it!

Also ordered some maxspeeding rods, and will try get a set of the 13:1 pistons so I can get VVTI working.

So I can hopefully rev to 9k with a bit more safety margin than factory rods.

Dang that is neat!

[RomanDave]

Here's an idea of how it goes/sounds with ITB and an 8300rpm limiter.

https://www.youtube.com/watch?v=Plcoepnwp8A

[mitch9521]

Those ratios in the C56 must make it feel like an entirely different animal.

[RomanDave]

I finished the airbox lid, and with everything installed it lost exactly 0% power.

Great! However it decreased the intake noise massively. Which is good and bad depending on what you're doing.

I had another play around with the VVTI situation.

I retarded the intake cam gear by two teeth, this allows a full range of movement without hitting valves into pistons with the 13.4:1 variants.

It's worked out well enough, but basically it's indicating that it would love to have more advance through the midrange, and would likely also love to rev out some more!

Some people have said that VVTI wont work at high rpm with the JUN cams and/or BC springs, but it works fine holding full cam advance right to 8500rpm.

To find the best VVTI angle, normally I'd measure the MAF output to optimize the airflow.

However since it's ITB the next best thing is to monitor how lean or rich it runs at full throttle through the rpm range.

Since the amount of fuel that gets sent is fixed, if more air comes in, then it will run leaner. And vice versa.

So on this graph, basically which ever line is the highest gives the best result.

The previous home position of the cam was somewhere around the 30 degree mark on this graph (yellow line) and you can see that now ~45 degrees advance is giving best airflow until very close to redline (red line)

Interestingly, the point that the curves cross over usually corresponds to peak torque. In this case that's happening at around 8k rpm.

I could probably rev it to 9 or higher and still see benefits, if it wouldnt likely cause mechanical issues such as a rod flying out of the block haha.

image.thumb.png.6eef4609c5848851303eea5896c516e8.png

[xnamerxx]

You might want to crack the vvt gear open and put some limiting blocks inside it.

With my 272 cams the car really didn't make good use of the extra torque below 5k anyway since the close ratio transmission never allowed me to be there anyway.

[RomanDave]

Originally Posted by xnamerxx

You might want to crack the vvt gear open and put some limiting blocks inside it.

Ahhh yeah thats what I ended up doing.
I moved the cam another tooth forward, and added a stopper. This gave a good spread of cam angles that responded well at various rpm. Ends up with about 17 degrees of cam advance over the standard position with no vvti.

1 tooth back vvti sweep (2).jpg

If I moved the cam back to its normal position, I'd end up losing out on top end. So will keep it where it is. Happy with that!

I went to the drags and it was heaps of fun.
I was having some issues with heat soak causing big ignition timing pulls off the line. I've never done anything with the car so far that leaves it stationary for long periods, saturating with heat.
So I was getting falsely high IAT readings (up to 70 deg c) which meant it was pulling around 7 degrees timing out, when I only run 25 deg timing max by 8500rpm.

So I'll try get that a bit better sorted for next time, I'll try take some sort of ambient temp reading and then clamp the IAT signal to this.

Good fun though and I was happy with my trap speed considering it's still got a standard header and exhaust.

14.7 @ 94.4mph, earlier in the day I did a 95.5mph when it was cooler.


261552846_10158824157182198_2891773982713736936_n.jpg


260799716_10158824169772198_3758099923225573096_n.jpg