Not so much a question thread, just getting a daydream out of my head….

Browsing halfrauds today, while waiting for a colleague to drop her car off, i found a haynes manual “build your own sports car”
basicly a haynes manual for a Locust kit car.

I now want a kit car to build 🙁
however if i was to get a kit car, ide want it to run on biofuel, so i dont have to feel guilty about driving for fun (dont question it,it works in my head)

i looove the diesel, for me its all about the grunt, rather than the revvyness,

however, diesels are, but thier very nature, physically heavier, bigger, and more complicated, than a basic little whippy petrol engine.

to keep weight down, my daydream is thinking, a 1.2ish diesel out of a city runabout, and then tune it up to generate a greater power output than it normaly would.
VW to a small petrol twin turbo, 1.4 pushing 170brake, why not do it to a diesel?
remap it?
bigger turbos
better air intakes?
maybe i’m possibly spouting poo?

as may be apparent, i dont know that much about cars (though i would say i know more than joe bloggs, just becasue i take an interest in these things)
if one could make it work, it would be good for endurance track days, though its a very big if.

any thoughts?

I’ve always wondered about doinging something similar but with gas. My old man used to have a K-Series 1.4 engined Metro GTi that went really well.
Often wondered what that engine running on gas would be like in a ariel or caterham style kit car would be like.

It is possible. VAG blocks are becoming lighter and more powerfull. Most kit cars tend to be based around old fords that tend to have heavy old EFi blocks. A nice VW 2.0 diesel, chip, bigger turbo and intercooler. Gear box tuned round the wrong way and a few mods to make it rear wheel drive and it could be a flying machine. Audio now run Diesel Le mans cars and the are kicking ass in them. Diesel is the future!!!

Definitely possible/feasible. Though I’d be looking for an alloy blocked diesel engine (anybody other than BMW or Honda build them yet?) rather than a cast iron one, even though cast iron blocks have slimmed down a bit over the years.

I remember back in the early 90’s Westfield even put a tuned up 1800cc Ford diesel engine in one of their cars, and that was pre the diesel power surge even. As you probably know, it’s about power to weight, and you can get a fair amount of power out of a modern turbo diesel engine with the right tuning. Even back as far as Y2k I heard of tuned Golf GTi TDi’s with in excess of 250bhp, and a mountain of torque, though that was primarily for circuit race cars.

On the weight front though, I don’t suppose even putting something like a diesel VAG engine in something like a kit car is going to be any worse than an old Ford Pinto or a Vauxhall 16V XE engine as a lot of kit car owners still do. The diesel torque will certainly make up for the 50kg or so weight penalty over a modern all alloy petrol engine.

The main problem you will have is turning all that torque into forward motion! You’d also need a pretty tall final drive ratio for the diff too.

a peugeot diesel won le mans didnt it, last year?

its the cast ironness combined with all the “extras” a diesel requires (turbos, intercoolers, dual compound clutches, 2 or 3 fuel pumps, fuel rails, injectors, yada yada yada)

but with an aluminium engine block? (ala bmw, not a cheap option) and a careful replacement of heavy parts with lighter equivelent….

Olly, you have quite a few misconceptions in your original post. I have a self-built Caterham, not the same as a kit car based on a donor vehicle but not a million miles away. Bear in mind the taxman dictates what you can run your car on, we are some way from growing our own fuel legally.

Most Lotus 7 type cars are using smallish petrol engines and no diesels in sight. Personally, aside from a Landrover Defender I think cars needs spark plugs, end of. If you want a small whippy engine in a Lotus 7 type car and want low emissions, don’t buy the diesel hype, get a car with a bike engine (there are a few variants).

VW to a small petrol twin turbo, 1.4 pushing 170brake, why not do it to a diesel?

It’s a “TwinCharger” actually, not 2 turbo’s but a Supercharger and Turbocharger rigged in tandem to provide smooth seamless boost right from tickover through to peak rpm.

remap it?
bigger turbos
better air intakes?
maybe i’m possibly spouting poo?

Bigger Turbo, big intercooler, bigger injectors, a decent remap. As with any internal combustion engine, it’s all about getting more fuel/air mix into the engine to produce more power, a turbo diesel is “relatively” straight forward to tune as you have forced induction so can simply turn that up so to speak (bigger turbo), and it doesn’t have a throttle body. All you need to do (I make it sound so easy! 😉 ) is get more fuel and air in!

http://www.locostbuilders.co.uk/viewthread.php?tid=16267

Think if it was me I’d got for a smaller 1.3 or 1.5 engine, peugeot perhaps. Would have to do something to link it to a rwd box, but at least your electrics would be easier!

db

If I was making a kit car I’d not bother making it green – you’re not going to use it for many miles or daily driving anyway. Its a fun car – accept you’re driving it pointlessly and enjoy it to the max, drive an eco car the rest of the time.

RIGHT

Your ideal engine is a VW 1.6 or 1.9 TD or even NA engine from 80s and early 90s VW Golfs etc. The 1.6 AAZ engine code is meant to be the better bet – particularly in a smaller car. With minimal tinkering the 1.9 can produce up to 250bhp, and the 1.6 almost as much. Tuning these diesels is easy as anything, all you need to do is ram in more fuel and air, and stop the pistons and exhaust from melting.

First step is to up the fuel screw to put in more fuel and open the turbo wastegate. You should get about 15psi boost and this will take you from about 75bhp stock on a 1.9 to 95 or so.

Then you can start doing things like fitting a bigger downpipe which will help with the exhaust gas temperatures (EGTs); swap the head bolts for studs and fitting a good head gasket; then you can fit a monster turbo and intercooler to get double the boost; then it’s larger injectors for more fuel. You can even go with water injection (which is apparently easy too although I don’t knwo the details) to cool the intake charge even more and allow you to burn even more fuel before you reach engine-melting EGTs.

Best of all, these older engines are indirect injection which means you can run them on pure vegetable oil (new or used) without modification and they will be fine.

It’s all on the http://www.vwdiesel.net forum. There are folk there with 230bhp diesels in tiny old cars that weigh next to nothing, and they are frigging quick.

By the way, diesels are easier to tune because you can just ram in more air and fuel and you don’t have to worry about detonation wrecking your engine.

If you want a small whippy engine in a Lotus 7 type car and want low emissions, don’t buy the diesel hype, get a car with a bike engine (there are a few variants).

Bike engined kit cars are only fit for the race track IMO. Great fun yeah (my mate used to have a Hayabusa engined Westfield), but totally impractical because of very short gearing, and very expensive on fuel because of their very revvy nature and the short gearing. No reverse gear to speak of either (well not without a major faff anyway).

Best engine for a road based kit car would IMO be the Toyota 4AGE. Totally bombproof (it’s a Toyota!), design based on the old Cosworth BDA so designed for performance use, and despite the fact it’s got a cast iron block, it’s only about 15Kg heavier than an equivalent K series or Ford Sigma engine. They rev to 8500 safely on standard internals, 200bhp is relatively cheap and easy from an NA unit, and 300bhp plus on a turbo’d or supercharged unit is quite feasible without spending major bucks. With custom race internals they can be made to rev to well over 10,000 revs safely (move over Hayabusa!) and push out over 150bhp/litre.

Oh, and it’s a piece of piss to buy a bellhousing for the engine to mate it up to a Ford sierra based gearbox (millions of options out there now from cheap and cheerful Type 9 from a Transit in a scrappy, right up to spunking £5k plus on a Quaife 6 speeder).

My intention is to one day build a fully faired in kit car (something like a Fisher Fury) for road use, with a 20V 4AGE engine running slightly lower comp pistons on otherwise stock internals, a small(ish) hybrid turbo, and around 200bhp but a torque “curve” as flat as table mountain from about 2500rpm right up to the redline at 8500rpm. Of course, would run it on bio-ethanol as well 😉

Oh and the AAZs can rev up to about 6.5krpm with a simple mod too.

had a TSi as a hire car once mboy, it was awesome 😀
only been around as a concept for 12 months though?, i wonder how much the electromagnetic clutch will cost to look after :'(

problem with a 1.9 i think is the weight, i get the feelin, in my 1.3T 2LHDi 206, 1T of that is under the bonnet, giving it a worryingly stong tendancy for the arse to swing out like a pendulum on smaller roundabouts.
its also killed my supension bushings 🙁
fine in a regualar car, but in a rollerskate of a car?
i think a full faired car would be more me too, but is it just a case of sticking a fairing over a “normal” spaceframe?

Oooo toys
(ive finished a report, and am killing my afternoon, avoiding getting more work to do)

You don’t need anything like 200bhp for a Caterham/Westy though, at anything over about 80 they’re noisy, windblown, uncomfortable places to be. You need to set them up for handling, not speed. They weigh nothing at all, so you don’t need masses of expensive grunt. My first Westy had a 2 litre Pinto in it, and I think was probably, if I’m honest, pushing out about 100bhp (on a good day) and that was still good for over a ton, which is about as fast as you want to go in a car you’ve built yourself TBH…

By the way, diesels are easier to tune because you can just ram in more air and fuel and you don’t have to worry about detonation wrecking your engine.

Diesels can still det if you allow intake temps to rise, just as with petrols?

Diesels can still det if you allow intake temps to rise, just as with petrols?

Of course, I was speaking simplistically though. Reducing air/fuel charge temps in a forced induction engine should always be the primary concern in my opinion, before outright power, as it affects many other things including reliability, drivability, longevity and fuel economy too as well as outright power.

problem with a 1.9 i think is the weight, i get the feelin, in my 1.3T 2LHDi 206, 1T of that is under the bonnet, giving it a worryingly stong tendancy for the arse to swing out like a pendulum on smaller roundabouts.

Nope, that’s all peugeots. Trust me, I’ve owned a few, they do like to swing their arse end out off the throttle!

A 1.9 VAG engine isn’t going to be light, but it’s only going to be about the same weight as a Ford Pinto I suspect, a common kit car engine. Also bear in mind you’d be mounting it lengthways, not transversely, and significantly further back than in a front drive car. In fact, most “7 type” cars have a rearward weight distribution anyway, exacerbated by lightweight engines, so a heavier engine will actually improve the weight distribution, if not the overall weight and performance.

Personally, if I was even entertaining the idea of building a diesel kit car, I’d probably look at doing a mid engined kit car rather than a front engined one, and try and find a written off VAG car with the 1.4 3 cylinder TDi engine in it. This engine is essentially the 1.9 TDi with one cylinder lopped off. OK, it’s direct injection so not as easy to tune, and you can’t run it on pure veg oil, but it’s still pretty easy to tune, and they’re 75bhp as standard, more than enough to punt 600kg of kit car along happily (besides the torque will be more like that of a 1.8 or 2 litre petrol engine) before being tuned. The Direct Injection engines are also WAY more economical (surely the main point of going for diesel in the first place?) than the non DI ones. The 1.4TDi Audi A2 achieved a combined cycle figure of about 65mpg, that same engine in a car weighing half as much is going to be very economical indeed!

My Westy was running an 1800 Zetec on twin 40’s.. ‘supposed’ to be putting out 155bhp from an engine that was originally 105ps spec.

Weighing just over 700kgs it was plenty quick enough for road use and quite a step up from my Austin Sprite 😉 More power to weight than that and I would’ve got myself into a world of trouble I’m sure
It’d do about 110mph..but not for long – I had faith in my build.. but 110 in a car with zero protection, no doors and the wind howling up your nose threatening to blow your eyes out is quite something. You’d need some serious BHP to get a car with the aerodynamics of a brick over 110mph.

It was completely impractical, but I loved driving it and the 7 months it took me to build it were worth every penny IMO.
Had to sell it as I moved to Canada and couldn’t import it here.

Have a google at the Westfield Weasel.

When I bought and specc’d my kit, it was all about Zetec/XE’s with 15″ wheels… pretty much as soon as I picked up my chassis etc, bike engines became the in thing (superb for the track and sound fantastic, but pretty sure you’d get fed up with it in traffic) 13″ wheels were also the thing to do with a view to keep the suspension working for the car, not the heavy wheels. Then it was VTEC and Duratec… not sure what the current vogue is though.

If I did one again… I would certainly consider diesel for the simplicity
I do love the idea of diesels and even the 1.7 Astra Eco tdi and 1.4 tdi VAG cars I’ve driven have been fun with an entertaining ounch when they go on turbo.
The tourqe diesels could generate would make getting the power to the road interesting though (probably much like the rediculously over engined V8’s)

To be honest, I’d probably agree with mboy and move away from open front wheels and go to something like a GTM Libra/Spyder. Or some kind of lightweight Cobra (mmmm)

I have a friend who built a locost as per the Ron Champion book… 250 quid my arse 😉

I highly recommend the whole experience though!

250 quid my arse

250 quid wouldn’t even buy you half the tools you need (hello, MIG welder anyone!) unless you’ve got them hanging around in the shed already! Haha

Diesels can still det if you allow intake temps to rise, just as with petrols?

They always detonate, it’s how they work. You won’t get any combustion before you inject the fuel, since the cyl is just full of air 🙂 So you can’t get pre-detonation no matter what you do – unless you advance the injection timing too much. Then it won’t matter if you’ve tuned it or not, you’ll still damage it.

The Direct Injection engines are also WAY more economical

A bit more, not way more. I get 45-50mpg from mine despite it being a big estate and there’s no intercooler, and a really low ratio tranny. I’d expect to see 53-55 on a long trip with those things fixed. My mate’s Octavia 1.9 only gets 45 despite being advertised at 57. VW seem to have got better at fibbing on the fuel economy tests, so I’d expect the A2 to get nearer mid-50s. Oh and the new engines are common rail – older TDIs are just direct injection, then there’s PD engines then common rail – each of which brings more economy.

Not sure if anyone has said this but biodeisel is very much not environmentally friendly.

Not sure if anyone has said this but biodeisel is very much not environmentally friendly.

True, but no vehicle fuel is environmentally friendly. Well until that one made from coffee waste is sorted!

Building a kit car whilst sticking to the manufacturer’s recommended donor parts can be tricky enough without deviating to fulfil some well intentioned ‘green’ notion. My first kit car was a heavily modified Mini Marcos utilising parts from umpteen places. Everything but everything was a problem. My second kit was a single donor Quantum, a pleasure by comparison.

Having enjoyed / endured the whole kit bug, can I suggest that if you do deviate from original spec you might hit some or all of the following problems; Alignment of engine, gearbox, mountings, rear diff, space / clearance for steering rack, suspension, brake calipers, wheels and tyres. ECU mapping, final drive ratios, speedo accuracy, brake servo vacuum issues. Wiring loom xwzzv27 not quite working with 27.5 guv.

Buy an MX5

A bit more, not way more. I get 45-50mpg from mine despite it being a big estate and there’s no intercooler, and a really low ratio tranny. I’d expect to see 53-55 on a long trip with those things fixed. My mate’s Octavia 1.9 only gets 45 despite being advertised at 57. VW seem to have got better at fibbing on the fuel economy tests, so I’d expect the A2 to get nearer mid-50s. Oh and the new engines are common rail – older TDIs are just direct injection, then there’s PD engines then common rail – each of which brings more economy.

I’ve not personal experience of running an old non direct injection Turbo Diesel, but those I know who have would say it’s as much as 15 to 20% difference, and that the old non-DI diesels are only a bit more economical than an equivalent NA petrol engine. VW/Audi (and all the others too) have got good at “massaging” economy figures yes, but the same goes for petrol cars as well as diesels. I’m now running a 95 TDi (first of the direct injections) VW Golf, and so far done only 2 1/2 tankfuls of fuel in it, but it’s averaged 51mpg so far even with a fair mix of spirited back road driving, and 80+ motorway cruising (naughty me!). The E90 BMW 320D I had as a company car before I got made redundant would average only 44mpg, despite claims of 58mpg on a combined cycle. But that BMW would, on a cruise at a constant 70mph on the motorway, return better than 60mpg, even as high as 70mpg on one day with a slight tailwind! Back road driving heavily affects the MPG figures on most diesels though. The Audi A2’s that the car rental company that I worked for part time when still at uni ran used to get 65mpg regularly, even more on a cruise!

mboy- Just sold my MK indy with a 954 Fireblade lump. There is no way you can say its just for the track. Ok so it had no reverse but other than that I could drive it round town, in traffic and on the track with no issues at all. I did 300 miles in it some days with no problems and returned up to 35mpg a lot of the time.
Even on the track i could get 17-20mpg! No normal car can do that.
And 150bhp/l??? Mine was 170bhp/l.

It was 470kgs wet… had no screen and no doors. Yet you could sit on the motorway fine. Also had it up to 125 without tooo many issues, tho i wouldnt want to stay there for long!

Back to the OP deisel is being done at the moment. Just a bit weighty in a car that is all about urr… weight!

Kit cars are cracking toys for good money at the moment, and most of them wont loose any money!

Have a mate whos got a Cossie Turbo Dax at 320hp if anyones interested….

Mates of mine that work at Lotus built a Lo-cost car to race in the series of the same name.
I think it was a very slightly tweaked Vauxhall Nova 1.3 engine. They did trackdays in it and were faster than TVRs.

With respect to diesels, I am not sure how easy it would be to stick one in a kit car, but the VAG 1.4TDi will remap up to 130bhp fairly easily with no other mods.
I’ve got the 1.9TDi in my Ibiza, the 130 version which has bigger intercooler/injectors/different manifold etc. to the 100 version and people regularly map it to 170bhp without too much bother. Standard torque is 228lbft and that generally gets upped to about 280lbft when re-mapped or clutch slip becomes an issue if they go any higher. Thing is, if you are building it into a kit car, you’d probably get a decent clutch anyhow (sachs or whatever) so could take it over 300lbft.

The 130 is quick enough in my car as standard, so in a kit car weighing about half the weight, I imagine it would be a hoot. I have never seen below 50mpg on a tank, with it normally sitting around 55mpg – most ever on a tank was something like 62mg. Most ever on one journey was 70.6mpg!

VW 1.4 PD triple.

Cracking little motor, nice and tunable. Not good with Bio though.

The Lo-Cost is a PITA to build, and will take up all of your time for ever more.

Get a Motorbike!

Conks

mboy- Just sold my MK indy with a 954 Fireblade lump. There is no way you can say its just for the track. Ok so it had no reverse but other than that I could drive it round town, in traffic and on the track with no issues at all. I did 300 miles in it some days with no problems and returned up to 35mpg a lot of the time.
Even on the track i could get 17-20mpg! No normal car can do that.
And 150bhp/l??? Mine was 170bhp/l.

I’m honestly amazed that you got 35mpg a lot of the time, that’s more economy than the bike the engine has come out of acheives (and the Fireblade weighed about 180kg, 1/3 what your car weighs almost, as well as the fact the gearing would be significantly shorter with approx 130mph top end instead of about 180mph). I do find that very hard to believe considering the Westfield Hayabusa my mate had he could not get better than 20mpg, and when thrashing it it was down closer to about 12mpg!

Don’t get me wrong, Bike engines in kit cars are a performance revelation, but they do have some significant drawbacks. For those that want a kit car as a pure toy, to drag out on Sunny Sunday mornings half a dozen times a year, they’re superb. And for the track enthusiast they’re great as they’re a very cheap way to lots of performance. But the short gearing, lack of reverse gear, lack of economy, snatchy clutch and lack of flywheel inertia, do not make for a particularly practical experience to be honest.

On the BHP/litre side of things, it’s much easier to get more power per litre with smaller capacity cylinders than it is bigger ones. Most 1000cc motorbikes (250cc per cylinder) are up around the 170bhp/litre mark as standard indeed. Most 600cc Motorbikes (150cc per cylinder) are well over 200bhp/litre as standard! Bigger capacity motorbikes like the Hayabusa are down closer to 135-140bhp/litre as standard. Achieving more than 150bhp per litre from a 1600cc 4 cylinder engine (400cc per cylinder) is pretty good going, all the bored/stroked Hayabusa engines that I’ve seen taken out as far as 1600cc have produced a max of about 250bhp without forced induction! And that’s a modern engine design. The Toyota 4AGE was originally designed in the early 80’s, and can be bought for peanuts (christ, I’ve seen entire Toyota MR2’s that have failed MOT cos of body rot, but engine is sound, for £200 or less!).

In my opinion, if you want something for road use with a motorbike engine in, get a motorbike! 😉

Anyway, one of these with a 1.4 TDi PD VAG engine, remapped to 110bhp or so (a quick 200 quid job), and probably running through an auto box, would make a great fun green lane and semi capable offroad and dirt track vehicle, and would cost peanuts to run!

I think you’d be best with a small, modern, low emissions, engine with a modest bit of tuning as you need to keep the weight down & diesels aren’t best at that!
Also the noise & vibration are not going to be known until its to late – in a light open topped car it may be really intrusive.
I’ve been involved with tuned diesels for years now & its amazing how far the science has moved on in the last few years, have a look here for 300+bhp Audi A3 & 400+bhp Lupo
I’ve been in the Audi & its a lot to get your head around the way it gathers speed through the gears!

Not sure if anyone has said this but biodeisel is very much not environmentally friendly.

Why? Made from recycled oil it’s fine. And I was talking about running on straight veggie oil which, if recycled, is about as eco friendly as you can get.

As for indirect injection VW engines being only a bit more economical than petrols, I just don’t believe that. I used to have a Passat 1.8 petrol saloon and I got 38 mpg in perfect conditions ie open country roads at 50-60, no town and no 80mph motorway. My estate 1.9 TD got 38mpg running on veggie oil and almost all town driving – so that’d be easily 42-43 on diesel. Town only remember. And some of the TDs including mine come with silly low gearboxes, so that screws it up too. The engine is significantly more economical than a petrol.

Snaps, I suggested an older IDI engine cos they’re really easy to work on. No electronics, all mechanical stuff.

Top marks for the thread title.

2 words Unfinished Project!

What an utterly bewildering and perplexing world.

It’s simply all too much for poor RudeBoy.

Bed time.

I built the first customer Haynes Roadster. This uses the Sierra underpinnings.
Yes you can put a diesel in, yes you can go for 250 hp but seriously why bother. I had an 893cc Fireblade engine. Pushing 100bhp at the wheels. 0-60 in 3 seconds, 20 miles to the gallon and still able to potter around at 30 in top.
I cannot understand the point in spending a lot of dosh on an engine when something is readily available for under £500 that will already do the job you are after.
Building one of these cars from scratch is a major feat, 75% fail to make it to the road. You will spend £5000 if you do it half right and no matter what you do, a bloke at VOSA will decide if you have to do it again. Expect trauma, expect tears and dream of fun and the wind in your hair.
Try locostbuilders website or Haynesd roadster forum for a better insight into the world of Locosting
you can pm me if you like for more details

Yes you can put a diesel in, yes you can go for 250 hp but seriously why bother.

The thread isn’t “how should I build my kit car” it’s “how can I run my kit car on biofuel”. Hence the VW IDI – cheap, old, simple, tunable…