Author Topic: Lotus Europa Race Car Collection  (Read 37571 times)

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Offline Mecky

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Re: Lotus Europa Race Car Collection
« Reply #75 on: Tuesday,September 24, 2024, 04:58:36 AM »
Hi guys,

I'd like to update the list most important upgrades, which I did to my car recently. I just modified the list from the very first post in this thread:
A short conclusion of our Lotus Europa S2 Type 54, which is prepared in accordance with Group H reglement for the BELCAR Historic Cup national (non-FIA) class:

Displacement: 1597 ccm
Power: 162 HP / 119 kW
Weight: 740 kg / 1631 lbs (mandatory minimum weight), without ballast: 694 kg
Ride Height: 70 mm / 2,76 in
Tank Capicity: 40 litres
0 - 100 km/h / 0 - 62 mp/h: 4,8 s
Max. Speed: 236 (212) km/h / 147 (132) mp/h (in brackets is the top speed with the short diff)
Rims: front: 8x13", rear: 9x13" Minilite / Revolution
Tyres: Pirelli Semislicks; 225/45/R13
Brakes: front: ventilated discs, rear: solid grooved discs; adjustable brake bias

Modifications:
Engine and Fuel System:
 - Renault 807 engine with crossflow-head (rebuilt in 2024)
 - racing H-shaft connecting rods
 - forged aluminium pistons for high compression
 - simplex timing chain
 - lightened crank shaft and flywheel
 - racing cam shaft Cat Cams
 - two 45 Weber DCOE twin-carburettors
- modified Banks exhaust manifold with Powersprint muffler Ø55 mm
- Aluminium pulleys for customized belt drive
- lightened rocker arms
 - Aluminium valve spring collars

 - two fuel pumps
 - fuel pressure regulator
 - oil catch-tank (1 litre)
- Mercedes W201 starter motor with increased torque and RPM
- Silicone ignition cables

Cooling:
 - custom-built aluminium radiator sitting right behind the grill
 - electrical water pump (80 litres per minute)
 - oil cooler installed in front of the radiator
 - ducted front boot to force the air flow through oil cooler and radiator
 - front bonnet with big hot air outlet
 - interior heater removed

Gearbox:
 - 5 speed Renault 395 gearbox (rebuilt in 2024)
- custom-built short differential (33/8 instead of 34/9)
 - Quaife ATB differential

 - sintermetal racing clutch

Suspension:
- completely adjustable (height, compression and rebound seperately) racing shocks Protech 600 Series
 - 2.25" racing springs (front 225 lbs/inch, rear: 200 lbs/inch) 

 - all rubber bushes replaced by uniball or polyurethane (incl. engine and gearbox mounts)
- tubular front wishbones
 - front upper whishbones camber adjustable
 - aluminium front hub carriers
 - rear whishbones completely adjustable
 - custom built rear hub carrier for BMW wheel bearings
- reinforced radius arm to hub carrier mounts (after fatigue caused a crash with the old ones)
 - M12 wheel studs

Brakes:
 - ventilated discs at front (Banks kit)
 - solid grooved discs at rear (Opel)
 - two circle braking system with steel-flex brake lines and adjustable brake balance between front and rear
 - master cylinders: front: 0,625", rear: 0,7"
 - air-hoses for front brake cooling
 - Ferodo racing brake pads

Bodywork and Interior:
 - lexan door- and rear-windows
 - flared front and rear wheel arches
 - completely removeable front bonnet
 - completely removeable light weight engine cover
 - Type 47 NACA ducts for fresh air into the engine bay
 - whole interiour removed except for the dashboard
 - passenger seat removed
 - aluminium fuel tank (right hand side)
 - removed rear boot
- GPS Lap Timer

Safety:
 - Tillett racing driver seat (fibre composite material)
 - 6 point safety harness
 - roll cage (FIA Appendix K spec; tube Ø38 x 3,2 mm)
 - fire extinguisher
 - emergency stop switch (can be operated from outside the car)

The recent changes are highlighted. I also attached a few photos of that new stuff.

Offline BDA

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Re: Lotus Europa Race Car Collection
« Reply #76 on: Tuesday,September 24, 2024, 07:53:08 AM »
Very interesting, Mecky! Without knowing the rules you run under or what parts are available, I can only say it doesn’t look like you’ve left much if anything on the table.

I’m curious. Have you achieved your top speed or is that calculated?

What fuel pumps do you use, how are they plumbed, and where are they mounted? (I’ve considered using two fuel pumps after my Facet cube pump failed but there is no room where I mounted mine in the inside of the frame ‘Y’ under the carbs. Maybe I can adapt your setup to my very different car.)

Do you run the stock rear stub axles?

Offline Mecky

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Re: Lotus Europa Race Car Collection
« Reply #77 on: Wednesday,September 25, 2024, 01:16:58 AM »
Hey BDA, thanks for the appreciation. You are right that most areas for improvements are already tackled. But with regards to my financial resources, the potential is not always used to the greatest possible extent. For example the brakes: I have seen a Europa TC race car from GB, which has AP racing brakes all round. That's the real deal. But my spec is already a big imrpovement, that's for sure. Similar issue with the gearbox. I could have bought a set of shraight cut dog-shifted internals and clutch-type limited slip differential for my 395 from the French company Transconcept for around 15 k. But I went for the shorter diff with Quaife ATB differential with my existing gear set, which cost around half the price. There is no glass ceiling for spendings on a race car, I'm afraid.

My rear wheel hub carrier and stub axle assembly is a similar story. The best way would be to go full Lotus 47-spec with Formula 2 rear hub Aluminium carriers or at least do the Spyder conversion with double wishbones. But I went a different route. To explain that, I have to go back in time many years. Back in 2011, I lost the left rear wheel while driving on the road. The central stub axle nut went lose. While checking the wheel bearings, it got obvious that the cast Aluminium hub carrier was worn out. In order to get a safer solution with stronger bearings, we checked possibilities and found that the stub axle of BMW 2002 rear wheels have fitting dimentions. Thus, we took BMW 2002 rear hub carriers with stub axles and wheel flanges. The hub carrier was cut to just the tube, in which the bearings are mounted. Around that, we built a self-constructed hub carrier from steel, which is not as light as original, but much more rigid and stronger. That decision forced me to build my own rear brake conversion kit, as it has to fit a BMW 4x100 mm PCD for the wheels. That's why I used a Opel Kadett front brake for my rear disc brake conversion. Opel uses the same 4 stud PCD as BMW. Not exactly AP Racing, but still a big improvement. And I'm also very happy with the BMW wheel bearing and stub axle conversion.

The top speeds are calculated figures. From experience with a GPS speedo, I'd say that the real value is a bit below than that. I guess, that the rear tyres are maybe a bit smaller in diameter than its written in the catalogue.

I use two fuel pumps, because my tank has a riser pipe, instead of an outlet on the lowest point. Thus the first pump (Manufacturer Pierburg) is just there to suck from the tank and provide to the Facet pump, which is especially for carburetor use. Before the carbs, there is a Filter King pressure regulator, which keeps constant pressure of 0.28 bar. The wirst pump is mounted on the right hand side of the engine bay. This is in order to be quite close to the tank. The Facet pump is mounted to the cross member between the two rear shock absorbers. Before the first pump, there is a filter installed to keep little pieces of explosion protection foam (which I had to cut into small cubes to put them into the tank) out of the pumps and carbs. You can refer to the photo of the engine bay from my last post to see all that.

Offline TurboFource

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Re: Lotus Europa Race Car Collection
« Reply #78 on: Wednesday,September 25, 2024, 03:26:06 AM »
Nice work Mecky!
The more I do the more I find I need to do....remember your ABC’s …anything but chinesium!

Offline BDA

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Re: Lotus Europa Race Car Collection
« Reply #79 on: Wednesday,September 25, 2024, 08:43:04 AM »
Thanks for the details. You’ve done a lot of interesting work!

I have seen drawings of the BMW stub axle conversion but hadn’t heard about the upright conversion.

Straight cut gears without synchros would be a big improvement but I hear you about the cost! 15K of any currency is a lot!

Good luck at your next race!

Offline Clifton

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Re: Lotus Europa Race Car Collection
« Reply #80 on: Wednesday,September 25, 2024, 12:15:10 PM »
Do you have pics of the Tillett seat in it? I have looked at them but I the I thought the height might be too much in a Europa.

Offline Mecky

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Re: Lotus Europa Race Car Collection
« Reply #81 on: Thursday,September 26, 2024, 12:31:18 AM »
Hi Clifton,

the seat is called Tillett B6 Screamer and fits quite OK. From my feeling, the seating position with the original seats is much better, but I have to use a racing seat for safety reasons. Lateral support is much better with the Tillett, of course. I laid it down with help of high-reaching mounting brackets. But I guess, the situation inside the cabin gets much easier, if you don't have a roll cage inside.

Here are some pictures with the old and new (detachable) steering wheel:

Offline cazman

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Re: Lotus Europa Race Car Collection
« Reply #82 on: Thursday,September 26, 2024, 03:06:29 PM »
I would very very much like someone that has knowledge of the "traditional" upgrade history for spring rates. Was it different back in the day? Have things become muddled over the years? I asked Richard at Banks why the fronts were so stiff (uprated) and he said he like to "drive from the rear".

I think I have posted about this before, as I have found a very good balance by experimenting on a track with multiple set ups. But, it all came together when I asked Barry Spencer what he recommended. That was his spec'd out Protechs at 160f /120r - which I ordered. Very nice and confirmed on a small road track at the limit with 185/60/13 R888Rs all around. I further refined this with a .75" front sway bar and home made adjustable rear sway bar, which reduced more roll. I mention the track because, it is very different from the autocross type driving. I can drift through turns in a very neutral position and induce under or over steer very deliberately.

If I add the roll bar rates with the effective rates of the springs, it comes to pretty even front to back. 
1973 Europa TCS

Offline Clifton

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Re: Lotus Europa Race Car Collection
« Reply #83 on: Friday,September 27, 2024, 11:52:42 PM »
I would very very much like someone that has knowledge of the "traditional" upgrade history for spring rates. Was it different back in the day? Have things become muddled over the years? I asked Richard at Banks why the fronts were so stiff (uprated) and he said he like to "drive from the rear".

I think I have posted about this before, as I have found a very good balance by experimenting on a track with multiple set ups. But, it all came together when I asked Barry Spencer what he recommended. That was his spec'd out Protechs at 160f /120r - which I ordered. Very nice and confirmed on a small road track at the limit with 185/60/13 R888Rs all around. I further refined this with a .75" front sway bar and home made adjustable rear sway bar, which reduced more roll. I mention the track because, it is very different from the autocross type driving. I can drift through turns in a very neutral position and induce under or over steer very deliberately.

If I add the roll bar rates with the effective rates of the springs, it comes to pretty even front to back.


The front is really not as stiff as the F/R spring rates look.  The rear has the spring mounted outside the LCA outer pivot making the spring more effective. The front is inside that pivot and angled more reducing the effective rate.  For your rates, front motion ratio is .68 x 160lb spring = 109lbs, rear motion ratio of 1.07 x 120lb spring =128 lbs. I measured the rear from the book, as I don't have Europa rear suspension.  I may be off a little but close enough for an example.

The higher the tire grip, the more spring, arb and camber you need to reduce roll and keep tire temps happy and wearing evenly. R888R's are pretty soft. If you did a lot of track or autoX, you would need more wheel rate or camber to keep the temps even and from killing the outer edges of the tire. Europa's or any car on all season tires are ok with softer springs as they can't induce the body roll that higher performance tires can.



Offline cazman

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Re: Lotus Europa Race Car Collection
« Reply #84 on: Saturday,September 28, 2024, 04:50:40 AM »
My point is that my rates are much closer ratio front to rear than the Uprated kits sold by the usual players. Mecky is 225f / 200r. Jensen Race Manual is 180f / 200r. Mine is 160f / 120r (and I probably should have 140r w/o swaybar). The uprated kits are 225-250f / 120-140r and no one seems to know how they got there. When I got my car it had the "uprated" set up and I thought it was dangerous.
1973 Europa TCS

Offline Clifton

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Re: Lotus Europa Race Car Collection
« Reply #85 on: Saturday,September 28, 2024, 05:12:44 AM »
My point is that my rates are much closer ratio front to rear than the Uprated kits sold by the usual players. Mecky is 225f / 200r. Jensen Race Manual is 180f / 200r. Mine is 160f / 120r (and I probably should have 140r w/o swaybar). The uprated kits are 225-250f / 120-140r and no one seems to know how they got there. When I got my car it had the "uprated" set up and I thought it was dangerous.

Preference. I run 650f/450r. Mecky runs what works for him. Kits are what the seller thinks works. Stock S2 arb is 55lbs, TC is 135 lbs. Jensen ran a 7/8" front bar too so that makes the front rate much higher. My 7/8" bar is 247,323, or 414lbs at full stiff. You can run a softer front spring or stiffer rear spring with a stiffer front arb and not be too loose.

If your car was 160f/140r, it would have more oversteer than the 160f/120r. Stiffer front vs rear is safer for most people. Most people don't go 100% and if they did with a loose car, it usually ends with them going backwards into something once they hit that limit.

Offline EuropaTC

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Re: Lotus Europa Race Car Collection
« Reply #86 on: Saturday,September 28, 2024, 09:08:23 AM »
My point is that my rates are much closer ratio front to rear than the Uprated kits sold by the usual players. Mecky is 225f / 200r. Jensen Race Manual is 180f / 200r. Mine is 160f / 120r (and I probably should have 140r w/o swaybar). The uprated kits are 225-250f / 120-140r and no one seems to know how they got there. When I got my car it had the "uprated" set up and I thought it was dangerous.
Without wishing to stray too far off topic, when I changed my spring rates I did a lot of research on the old Yahoo email list archives and pulled out all I could find that folks had used. Some appeared to have logic, some I just couldn't figure out. I read several books on suspension design, measured/weighed bits of my car and eventually ended up with 250F, 160R which I like although probably too harsh for some tastes on our (poor) local lanes. 

I'm no driving god and don't have the luxury of a racetrack so it was a combination of theory, maths and driving round to see how it felt to me. The front felt ok from the start, I had a couple of stabs at rear springs before deciding on 160 which, as you posted, doesn't seem to fall in line with convention. But as Clifton says, it's a personal thing and that was where I felt most comfortable; I'm pretty sure I couldn't live with his 650/450 springs without shaking out my fillings but as always, it's what works for whatever driving style you need.

The maths comparison at the end threw up some interesting points. Firstly, with my car measurements, running the OEM 115F/75R gave approx. effective spring rates of 76/75 when the angle & geometry came in. My 250/160 came in at 164/160, fairly similar ratios. 

It also showed the OEM spec gave a wheel frequency of 1.2F, 1.4R with 13" wheels, /70 tyres, etc. I ended up with 1.8F, 2.0R but with 15", /50 aspect ratio tyres. What I found interesting was that when I'd finished, the ratios of F:R wheel frequencies were very similar to the OEM Lotus settings with the OEM at 0.91, mine at 0.92. 

So it wouldn't surprise me if folks selling uprated kits haven't based their designs on similar principles and just "boosted" the original wheel frequencies but keeping the balance similar.

Offline dakazman

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Re: Lotus Europa Race Car Collection
« Reply #87 on: Saturday,September 28, 2024, 06:03:57 PM »
  Thanks Mecky , for giving me a long shopping list for Christmas. 🤣
 You got some great team there and I’m amazed at what you’all accomplish.
Dakazman

Offline Mecky

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Re: Lotus Europa Race Car Collection
« Reply #88 on: Friday,October 04, 2024, 12:21:15 AM »
My car doesn't have an anti-roll bar mostly because it came without one. A previous owner had it removed in order to lower the car, even using motor cycle shock absorbers to get the front further down. After installing proper shock absorbers, the car drove already quite well from a mechanical grip POV. We had several other problems to tackle first, in order to make the car reliable. Now, that it finally seems to be reliable, I slowly started to work on the suspension set-up. I increased front spring rates from 180 (Year 2022) to 200 (Year 2023) and then to 225 lbs/inch (Year 2024), in order to reduce (front) body roll, which was immense with the 180 springs. You can see a nice comparison of 180 and 225 front springs in the pictures below. (Please note: When both these photos were taken, the nose of my car was already leaning slightly to the right, even when the car stood still. This was down to a uneducatedly executed front end repair job. The sloped nose is more obvious on the photo from 2024. Fortunately, this blemish is corrected now. One good thing that came with the crash repair.)

Obviously, the right next step is an anti-roll bar, but it has to be a customized one, as my Protech shocks don't have the stock mounting points. But I have already seen two or three very nice solutions, which I may adapt in the future.

Offline TurboFource

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Re: Lotus Europa Race Car Collection
« Reply #89 on: Friday,October 04, 2024, 03:27:58 AM »
I mounted mine from the upper control arms bolts as the studs had been broken off the shocks in the past and I wanted to avoid that in the future.

Pic is mocking it up …
« Last Edit: Friday,October 04, 2024, 04:49:20 AM by TurboFource »
The more I do the more I find I need to do....remember your ABC’s …anything but chinesium!