Turboing the K3VE - differences with K3VET?

Questions and Answers
1

Hi all,

Just weighing up a project for a Copen with the 1.3 K3VE. Could drop in a K3VET from a YRV but these are getting a little harder to come by. If I go with converting a K3VE then rather than just drop in a used K3VET it would be a rebuilt K3VE.

If I turbo the K3VE I know it would need K3VET pistons (forged), different injectors, intercooler, pipework, standalone ECU, exhaust manifold, oil feed line and return line for turbo.

Would it need anything else (or is anything else recommended) to convert the K3VE to turbo and do the pistons alone drop the compression down to match the VET?

Is anyone producing forged conrods for the K3VET at the moment?

I have read about changing the head and cams but is this necessary? Does the VET head lower the compression further? Can I run the stock head and cams maybe with stronger valve springs fitted? I read something about the valves being open at the wrong time with stock cams in a forced induction setup.

I know the car will need other supporting mods (gearbox, etc) but just focusing on the engine plan at the moment.

Thanks in advance for any help.

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2

check the part no. of the VE and VET regarding conrods

3

Hi LegendaryD,

We’d love to see some pics of your Copen. Could you go to the new people section and post an introduction please? That might also prompt a few other people to answer your questions. What are you planning on doing with the Copen? Daily, project, performance or max power?

Regards,

Gormsby

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It seems tricky to find the engine part codes online, but as far as I can see the K3VE is 13201-97401. I found a random site with some aftermarket rods for the VET and the measurements matched.

I have found a couple of forged options online but not sure if any of them are reputable so hoping somebody can advise who has actually bought some. Or does anyone know what HP the stock rods tend to be able to cope with?

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5

Hi Mr_Gormsby,

Not bought a Copen yet. Assessing a project to make sure I can achieve what I want to within budget. As per my 1st post, looking at turboing the K3VE or swapping in the K3VET from a YRV. looking at a street-legal Copen, but setup for trackday use. Not set a hard goal for bhp yet as that will all depend on costs. Would like to be over a stock YRV K3VET. Around 170 to 200hp is probably a nice goal but will adjust based on costs.

i have picked up a lot of info from the forums but still a few gaps in my knowledge that I am hoping to fill in order to avoid as many mistakes/issues as I can.

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6

Have you tried partsfan yet?

For example here are YRV schematics: https://partsfan.com/daihatsu/jp/e962946963da645bdbf71c3a3e4a2a03/

7

The engine ought to be capable of that, but the bit you are going to need to spend the big bucks on will the ‘everything else’

A standard manual gearbox won’t cope with that power. The reason all the YRV Turbos are auto is because no Daihatsu gearboxes would tolerate the torque that the 130bhp K3-VET puts out. You’re aiming for a 50% increase in that power/torque so you’ll blow up gearboxes left right and centre.

There is a solution, but its a £3k (minimum) Compact Motorsport gearset, plus fitting & installation.

Then there is the brakes. I have a notionally 110bhp Sirion Rally 2 and the brakes are barely adequate if I’m honest. Again, you’re going to have 80% more power/torque than I have on tap, and at a much lower RPM therefore more usable. You will need to upgrade the brakes quite substantially, not sure on cost but budget for a grand at least for parts + install. I believe that you can modify MX5 brakes to fit, but its not a simple process. You might need bigger wheels & tyres to clear bigger brakes too if you’re not already running 15" wheels.

With that much power on tap you’d be wise to fit some chassis bracing, Ultra Racing have some good stuff but you’d be looking at £500+ for a comprehensive setup. And quite possibly improved suspension setup too, some adjustable coilovers from a decent outfit will probably be another grand S&F?

So just to set the scene, thats £6k+ before you spend a penny on the engine. All do-able, and largely off-the-shelf, but for that much money you could just go out and buy a 200bhp 2 seater soft top thats ready to go.

I’ve said it before, and will say it again, play to the Daihatsu’s strengths. Its light and nimble, make it HANDLE and you’ll have a far more enjoyable car even with standard engine and gearbox. For <£1k you could get a full set of chassis braces, polybush the standard suspension, upgrade the ARBs and fit a set of semi-slick tyres to the standard wheels and you’ll out-handle cars costing ten times that much. It’ll also drive nicely on the street.

I don’t mean to pour cold water on your ideas, but you should consider the big picture. If you want big power then starting with a Daihatsu isn’t the way to go. If you want a car that will out-handle a lot of other cars then its an excellent starting place.

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@ marc0tjevp Excellent. Thanks for the link. That will be very handy and I have bookmarked it.

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@Granger Yes, I know it will require other supporting mods. I was going to ask questions about those in other threads to try and keep this one clean (ish) by just asking the engine side of things here but totally happy to discuss it all on this one thread. Didn’t want to upset anyone as I am new to the forum and I know some forums get narked when threads are too broad.

The potential list I have at the moment is sitting around the 9k mark and I am sure I have missed things. As well as all the engine related items the list has shocks, 2 braces, rear anti-roll bar, gearbox upgrade, LSD and more.

I had looked at the straight cut gears from Compact. Separate question that I was going to ask at a later date was why do they do a 3/4/5th gear set as well as the full set? Do some people just straight cut 3/4/5 as they don’t use the power in 1st and 2nd so less likely to blow up those 2 gears?

I knew the cost would be high, as would the uniqueness. As you say, there are lots of other cars you could buy in that budget and there is always the chance I go that way. Keen to go a different way than the norm.

At the moment I am leaning towards something along the lines of what you advised - braces, polybushes (I had thought of those but left them off my list so thank you for the reminder), shocks and brakes as the early mods then budget towards the power upgrades from there. A stepped plan will make more sense than trying to do it all in one big step.

I have been seeing upgraded brakes for around the 1k mark,. Did stumble across a post last night from someone in South Africa who was fitting different brakes but haven’t had a chance to look at the feasibility of what he planned. The brakes he was fitting sounded rather large. The Wilwoods that Compact sell are 262mm. This guy was looking at 4-pot calipers from an old 2000 subaru with discs from a T-Sport IIRC. But the quick research I did at 1am seemed to suggest that those T-sport discs are pretty big. Will look in to it more over the next couple of days. At the end of the day the last thing I need is a brake setup that is doesn’t fit, is unsafe or just plain fails for the sake of saving a few £. I didn’t know that MX5 brakes may fit. That is something I will look in to. I am sure you are correct that it will need bigger wheels - that’s part of what made me question the plan from the gentleman looking at T-sport discs.

I honestly don’t see this as you pouring cold water on the idea. This sort of feedback is exactly what I need. Most of the info I have found has been from forums such as this and without the info from people like yourself I wouldn’t have even known where to begin. It might take ages for this idea to come to fruition. It might end up way over the budget I can afford. But I like to have a clear plan ahead of starting any project.

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10

No problem, and glad to lend any experience I can!

So, first of all - Gearing. Compact sell a 3rd/4th/5th set because 1st and 2nd gears as standard are quite strong, generally if you’re going to blow up a gearbox, you’ll lose 3rd then 4th then 5th in order of likelyhood! Not sure about you, but the synchromesh between 1st and 2nd on my 120k mile gearbox isn’t that healthy, so something else to consider if you have the gearbox out and in bits is replacing the synchros.

I’d say start with the modifications you have already suggested - braces, polybushes (siberianbushing.com is your friend here) and refreshed dampers will make it handle really nicely. You might not even need to go with adjustable coilovers, just new dampers might make a big improvement. For brakes, you can get upgraded compatible discs and pads - for example Black Diamond do a set of performance pads & cross-drilled + vented discs for under £100 delivered. I have the pads on my sirion, they’re not as good as DS2500 pads are, but they’re better than standard. And they literally bolt on, same diameter, same stud pattern. The thing you will probabaly find though is that the braking force isn’t as good as it could be, which means new master cylinder time. Read about on here as there are some bolt-on options for this, but its a little bit of a dark art! You don’t need much bigger master cylinder to give a lot more braking effort and you definitely can go too big!

Something else to consider is that you can upgrade the K3-VE engine with the Sirion rally exhaust cam - there is a schematic on here - to give you a reliable 110bhp and 7800rpm redline which makes for a lot of fun. You don’t get the turbo torque so a stock gearbox will survive (mine is original and 120k miles old) even if you use all the revs. It doesn’t sound massive but thats ~150bhp/tonne which is plenty in a small car with well sorted handling.

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That explains the 3/4/5 set then. I did have new synchros in my list, possibly with new gearbox bearings as well.

I will check out siberianbushing and see what they have. I glanced at it quickly and couldn’t see the Copen on there, but I’ll just check the sizes and find what they have to fit. They seem to have a large range.

I didn’t know about the sirion rally cam. That sounds like a great idea.

Thank you for the advice.

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This is the tech thread on the exhaust cam FYI

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Surely that 110hp is with the ve2 high comp pistons as well? This is a ve engine so lower comp

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Sorry, yes you are right - for the full 110bhp you’d need the high compression pistons too.

I’d suggest that with the stock K3-VE you’d probably make 95-100bhp with the rally cam?

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