500hp per tonne lotus elise R500 HPE
Discussion
Greetings chaps...thought i'd share my new build thread in case anyone here is interested 
Just over 5 years ago I did this:
https://www.pistonheads.com/gassing/topic.asp?h=0&...
Then a year later I decided it was time for a mid life crisis, I was 34 after all, so I quit my job and tried to earn a living playing with cars. The amount of gratitude I feel to all of my customers deserves another thread all of its own so I won't go into it in too much detail, but despite the last 4 years being phenomenally stressful and difficult, they have to be the most enjoyable years of my life so far.
Just over three years ago, after building a couple of customer cars that were loads better than my own I decided a quick winter refresh was in order so I tore my perfectly working elise apart and parked it in a barn.
Three years later having done two thirds of bugger all to it things got so bad I considered selling what was left of it, however after some rest over the christmas break, several long conversations with various people and a slight change of circumstances I'm doing the build i've been dreaming of for the last 4 years.
If you saw my previous build thread you'd have seen that I picked up the registration K20 HPE for the car. That registration is now on my daily runabout because I got another for the elise, R500 HPE, which ties in perfectly with my plan for the car, which is to build a 500 hp per tonne Honda Powered Elise.
In order to hit 500hp per tonne I'm targetting 650 kilos and 330hp. The engine will be a normally aspirated honda of course...but a little different to the norm. I'm building a 2.2 similar to some of the customer builds i've done, except mine will be standard stroke and very big bore, so in effect a short stroke 2.2l engine. Its going to have a few tricks that don't make their way into customer builds for various reasons, 2 ring race pistons for example.
In thruth, I haven't done nothing to it over the last 3 years, but its a tiny amount of work in the scheme of what i've got ahead of me.
As it stands the car looks like this:
Its almost completely stripped, even down to the wiring loom. I had the cage made a while back by a top motorsport fab place and its very light. I managed to get hold of a lightly used Tillet B7 seat which is lighter than the runners its on and the rest of the car is sitting on fresh bushes and bearings throughout, but thats about it.
I started collecting a few parts for the engine and i've been porting my own cylinder head I have almost no idea what i'm doing so the results will be interesting...
Being a much bigger bore than standard has several advantages. I can run substantially bigger valves than standard but still not suffer from shrouding of the valve. As i'm going for gold with the engine i'm running 2mm bigger inlets and an extra large set of throttle bodies with 54mm chokes so the ports are getting opened out to match the huge throttle body manifold. You can see here how much material needs to be removed from the already gargantuan K20 port to match the manifold.
Here's one nearing completion:
It doesn't stop there though. I'll be fitting a very trick clockwise motion flywheel that'll allow me to fit a 5.5" twin plate clutch to it. Whilst light flywheels have a noticable effect on the response and inertia of an engine, its the clutch that makes the biggest difference. Reducing the diameter from over 8 inches for the standard honda clutch to 5.5 is mind boggling, its the setup that most single seaters run so it'll sound suitably bonkers....and be undrivable, but who cares.
The crank, rods and pistons are pretty special too. I'll go into some more detail on those when i've got some pictures, but the end result is an engine that feels like it has no flywheel. Think mclaren F1 or Porsche carerra GT and you're somewhere near, but not quite as responsive
So here goes, to say i'm excited is an understatement. I'll be doing all the evenings and weekends I can spare on it, which by my previous experience means many late nights listening to radio 2, but at least I don't have to do it on the drive in the snow any more!
Stay tuned.
Just over 5 years ago I did this:
https://www.pistonheads.com/gassing/topic.asp?h=0&...
Then a year later I decided it was time for a mid life crisis, I was 34 after all, so I quit my job and tried to earn a living playing with cars. The amount of gratitude I feel to all of my customers deserves another thread all of its own so I won't go into it in too much detail, but despite the last 4 years being phenomenally stressful and difficult, they have to be the most enjoyable years of my life so far.
Just over three years ago, after building a couple of customer cars that were loads better than my own I decided a quick winter refresh was in order so I tore my perfectly working elise apart and parked it in a barn.
Three years later having done two thirds of bugger all to it things got so bad I considered selling what was left of it, however after some rest over the christmas break, several long conversations with various people and a slight change of circumstances I'm doing the build i've been dreaming of for the last 4 years.
If you saw my previous build thread you'd have seen that I picked up the registration K20 HPE for the car. That registration is now on my daily runabout because I got another for the elise, R500 HPE, which ties in perfectly with my plan for the car, which is to build a 500 hp per tonne Honda Powered Elise.
In order to hit 500hp per tonne I'm targetting 650 kilos and 330hp. The engine will be a normally aspirated honda of course...but a little different to the norm. I'm building a 2.2 similar to some of the customer builds i've done, except mine will be standard stroke and very big bore, so in effect a short stroke 2.2l engine. Its going to have a few tricks that don't make their way into customer builds for various reasons, 2 ring race pistons for example.
In thruth, I haven't done nothing to it over the last 3 years, but its a tiny amount of work in the scheme of what i've got ahead of me.
As it stands the car looks like this:
Its almost completely stripped, even down to the wiring loom. I had the cage made a while back by a top motorsport fab place and its very light. I managed to get hold of a lightly used Tillet B7 seat which is lighter than the runners its on and the rest of the car is sitting on fresh bushes and bearings throughout, but thats about it.
I started collecting a few parts for the engine and i've been porting my own cylinder head
I have almost no idea what i'm doing so the results will be interesting...Being a much bigger bore than standard has several advantages. I can run substantially bigger valves than standard but still not suffer from shrouding of the valve. As i'm going for gold with the engine i'm running 2mm bigger inlets and an extra large set of throttle bodies with 54mm chokes so the ports are getting opened out to match the huge throttle body manifold. You can see here how much material needs to be removed from the already gargantuan K20 port to match the manifold.
Here's one nearing completion:
It doesn't stop there though. I'll be fitting a very trick clockwise motion flywheel that'll allow me to fit a 5.5" twin plate clutch to it. Whilst light flywheels have a noticable effect on the response and inertia of an engine, its the clutch that makes the biggest difference. Reducing the diameter from over 8 inches for the standard honda clutch to 5.5 is mind boggling, its the setup that most single seaters run so it'll sound suitably bonkers....and be undrivable, but who cares.
The crank, rods and pistons are pretty special too. I'll go into some more detail on those when i've got some pictures, but the end result is an engine that feels like it has no flywheel. Think mclaren F1 or Porsche carerra GT and you're somewhere near, but not quite as responsive
So here goes, to say i'm excited is an understatement. I'll be doing all the evenings and weekends I can spare on it, which by my previous experience means many late nights listening to radio 2, but at least I don't have to do it on the drive in the snow any more!
Stay tuned.
Time for some crank porn.
This is a standard K20 type R crank shaft:
They're forged steel and virtually unbreakable but pretty heavy.
This is a Clockwise motion billet steel stroker crank (bottom) and the crank i'm using in my engine (top). Notice they're both single counterweight and as a result much lighter.
You'll probably also notice that mine looks like an oem crank rather than aftermarket. That's because it is...its out of another K20 but not a type R. Its also got smaller big end journals which in turn means smaller rods and even less reciprocating weight. The rods are pretty trick too, also clockwise motion items. As I mentioned they have a smaller than usual big end which makes them lighter even than the usual rods I put in the 2.2 stroker builds. They're also longer, which is facilitated by the 2 ring pistons, which have a shorter distance between the gudgeon pin and the crown. Longer rods are great because they mean the pistons 'hangs' at the top of the bore longer and whips around the bottom faster, which in turn means more bang for your buck. Its a very small incremental improvement, but with the big bore and bigger valves it all adds up.
This is a standard K20 type R crank shaft:
They're forged steel and virtually unbreakable but pretty heavy.
This is a Clockwise motion billet steel stroker crank (bottom) and the crank i'm using in my engine (top). Notice they're both single counterweight and as a result much lighter.
You'll probably also notice that mine looks like an oem crank rather than aftermarket. That's because it is...its out of another K20 but not a type R. Its also got smaller big end journals which in turn means smaller rods and even less reciprocating weight. The rods are pretty trick too, also clockwise motion items. As I mentioned they have a smaller than usual big end which makes them lighter even than the usual rods I put in the 2.2 stroker builds. They're also longer, which is facilitated by the 2 ring pistons, which have a shorter distance between the gudgeon pin and the crown. Longer rods are great because they mean the pistons 'hangs' at the top of the bore longer and whips around the bottom faster, which in turn means more bang for your buck. Its a very small incremental improvement, but with the big bore and bigger valves it all adds up.
Edited by danwebster on Friday 19th January 12:58
This mornings job was to remove the pedal box and start the refurb, it's not in bad condition but I'll probably shot blast it all and then re anodise it to get it looking spot on.
Someone recently suggested replacing it with an aftermarket pedal box, but they're such a lovely thing and so light I couldn't possibly. I will be converting it to dual cylinder with a bias bar on the brake pedal though.
Someone recently suggested replacing it with an aftermarket pedal box, but they're such a lovely thing and so light I couldn't possibly. I will be converting it to dual cylinder with a bias bar on the brake pedal though.
I've stripped all of the brake pipes out of the car and started to clean the nooks and crannies. Leaving it sat in a barn for 3 years means its very dirty!
There are a few patches of surface corrosion to deal with too.
The interior is starting to clean up but its going to take a lot of elbow grease.
There are a few patches of surface corrosion to deal with too.
The interior is starting to clean up but its going to take a lot of elbow grease.
Todays excitement has been the delivery of lots of shiny parts that have got me more excited that a small child at Christmas.
First came the custom large port Clockwise throttle bodies:
Its not the easiest to make out from the picture but they're much bigger than the usual version that i've been fitting to customer cars with great success:
They're absolute works of art, made entirely from billet - the ram pipes, backplate, everything. The details are stunning...
The matching carbon airbox is rather pretty too..
Next came a few more engine bits including these beautiful pistons, which are 2 ring and extremely light and will get me up somewhere near 13:1 compression.
Rods too...these are super light and very trick. They have a smaller big and little end than standard rods as well as being longer than standard which is facilitated by the height of the pin in the piston.
But the thing thats got me most excited is the clutch and flywheel combo.
It might look like a normal flywheel and clutch but its not.....here's a couple of standard sized ones for comparison.
As you can see, two of them now look massive and one looks tiny! The two larger flywheels are both clockwise motion ultralite items, 2.9kilos each, and imbue the engine with throttle response to die for......mine is 1.2kilos :lol:
The biggest difference comes about from the clutch though. On the left is a standard clutch cover. In the middle is a twin plate 7.25" race clutch, which transforms the response of the engine because of the mass being moved inwards by quite a distance over the standard clutch which is almost 9" in diameter.
Mine is a 5.5" twin plate clutch and I haven't got the words to describe what a difference that makes. Its the setup thats in use in many single seater race cars, but as far as I know no one has put one in a car yet :lol:
As you can see, its tiny compared to even the 7.25" setup.
So i'm wetting myself at the thought of getting this thing built as you can imagine!
First came the custom large port Clockwise throttle bodies:
Its not the easiest to make out from the picture but they're much bigger than the usual version that i've been fitting to customer cars with great success:
They're absolute works of art, made entirely from billet - the ram pipes, backplate, everything. The details are stunning...
The matching carbon airbox is rather pretty too..
Next came a few more engine bits including these beautiful pistons, which are 2 ring and extremely light and will get me up somewhere near 13:1 compression.
Rods too...these are super light and very trick. They have a smaller big and little end than standard rods as well as being longer than standard which is facilitated by the height of the pin in the piston.
But the thing thats got me most excited is the clutch and flywheel combo.
It might look like a normal flywheel and clutch but its not.....here's a couple of standard sized ones for comparison.
As you can see, two of them now look massive and one looks tiny! The two larger flywheels are both clockwise motion ultralite items, 2.9kilos each, and imbue the engine with throttle response to die for......mine is 1.2kilos :lol:
The biggest difference comes about from the clutch though. On the left is a standard clutch cover. In the middle is a twin plate 7.25" race clutch, which transforms the response of the engine because of the mass being moved inwards by quite a distance over the standard clutch which is almost 9" in diameter.
Mine is a 5.5" twin plate clutch and I haven't got the words to describe what a difference that makes. Its the setup thats in use in many single seater race cars, but as far as I know no one has put one in a car yet :lol:
As you can see, its tiny compared to even the 7.25" setup.
So i'm wetting myself at the thought of getting this thing built as you can imagine!
Thanks for the kind words chaps, its certainly more enjoyable than having a proper job!
Caddyshack said:
About time I had a good build thread to read. Love the concept....keep the updates coming.
Is bigger always better on an N/A head and bodies? I thought you needed smaller ports for speed of flow? Not tha I know, most of my cars have dirty power turbos
Thats a great question and depending on who you ask you may get very different answers. What I do know from empirical evidence obtained from the engines i've built for customers is that a normally aspirated 2.2 K20 with a standard port head and standard valve sizes will make around 280hp. The same engine with a ported head and 1mm bigger valves will do around 15 to 20hp more....so there's only one way to find out if bigger is better Is bigger always better on an N/A head and bodies? I thought you needed smaller ports for speed of flow? Not tha I know, most of my cars have dirty power turbos
To be honest the 2.2’s with standard sized (albeit ultra light) flywheels already spin up like bikes, mine should be on another level entirely.
Here’s a customer 2.2 build I did, I like to make sure the tyres are scrubbed before handover.
https://youtu.be/kpVRNSkWGy4
Here’s a customer 2.2 build I did, I like to make sure the tyres are scrubbed before handover.
https://youtu.be/kpVRNSkWGy4
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