186 replies to this topic

[Nev]

IMO (and a couple of other respected tuners I know) it is usually better to use the 'hot crown pressed' Mahle (ie semi-forged) pistons. They are good for 500 BHP at least, probably more yet allow much tighter piston to bore clearances. I only installed C20LET ones in mine but the Z20LEH ones are better (both in metal & anti-friction coating). I believe Klasen bought up all the stock of the oversized Z20LEH ones from Mahle (ie the 86.5 mm ones), so you would need to buy from him I think. It's a shame you live so far away, Id love to build another good engine up with someone. Are you considering using solid lifters in your new engine. I can't prove that mine help, but my gut instinct says they have helped a lot with the engine breathing. If you did install them, it allows you to rev the engine much harder (I set my red line at 8000 RPM) and then the next weakest point in the chain becomes the oil pump which may then start to cavitate the oil at approx 7750 RPM. If you were to increase it's pulley size (to reduce its gearing) or replace the oil pump with a scavenging system then you could take the revs up much higher, maybe 9000 RPM or higher. An oil scavenger and 9000+ revs will make a proper track animal, not a lazy old road car like mine

Edited by Nev, 22 May 2012 - 06:42 AM.

[cs_]

Nev, honestly I do not have ambitions to still go for more power (especially I do not like very high revs). If I will build another engine the aim will be to achieve the same drivability and same power and torque, but to gain more durability. The specs of my current engine could also be done with a 2 litre and LEH pistons. This could be the way to go, IF the Klasen engine starts to fail early. Which is still not clear right now. For me it is very important that the car has trackday capabilities. Pushing the power much further would bring no further use for this aim, it even just would make things worse for me. Personally I do not like cars that are good on the quartermile but fail on curvy roads or race tracks. It's always a compromise. I do not drive quartermile more than once a year but I do drive a lot on normal roads and on some occations on race tracks. So the compromise for me is less power (383 is still a heck of a lot), more drivability. That's why an even bigger turbo charger is a no option for me. I do have a friend that has reached some 430PS with a Garrett charger. This engine goes like hell. It's a burner on the straight, but no option anymore for tracks. Not my case! There are certain points in your life when you have to admit "it's enough". With 383PS and the luck of a still very harmonic drivability and wide power band for me this moment is now. I am in the good position that the engine still behaves like a "normal" stage 3 which is a rather success I have been hoping for but not really did expected. Will keep that in general and enjoy driving this way as long as it lives. So, it is good as it performs now. I am happy. Driving this car in normal traffic is so fast, other cars seem to stand in the way, not moving, and you buzz around between them like a berserk wasp. And what's remarkable: did some first intensive testing and it's clear right now that more HP almost bring no better performance at low speeds, physics are simply incorruptible. Even with good tyres 1.4g is the limit. Every additional HP only show up at higher speeds. You get better 100-200 times, you reach 250km/h faster than cars with less HP, I now could reach 310km/h if I had a longer gearbox. I drove with a friend who has 330PS in his VX. And the sprint from standing still made almost no difference anymore. On paper I have 13% more power (his 328PS EWG, mine 383PS DIN) but my car weighs a lot more than his. The differences get obvious accelerating from 200km/h up. Because of the air resistance which steal some 200PS at 250km/h the remaining power on my side is then around 85% higher than his. So as a resumee: why do I need additional HP if the only advantage comes at speeds that you not really drive that often? Even now 0-250km/h are done in well under 20 seconds. A Gallardo LP560-4 E-Speed needs some 18 seconds. I am playing in the same league now. That's enough. And every time I accelerate at low gears feeling the Quaife being stressed and the Traction Control hammering the engine into pieces I now the limits of sanity are still left. Some time, you have to stop for reason. For me, this is now! Just wanna have some fun now. For the whole invest, stress and pain.

Edited by cs_, 23 May 2012 - 04:20 AM.

[cs_]

now => know

Sorry, cannot edit anymore

[cs_]

Btw. I did take a look inside my old LEH Turbo Charger. He oiled a lot, the manifold has a crack so I dismounted it. Have a look at the compressor wheel:
Did about 28.000km.

[rob999]

Glad you're 'just' going to enjoy using it now Carsten. Hope this engine lasts a while

Edited by rob999, 23 May 2012 - 05:28 AM.

[cs_]

Last weekend I learned that the Racelogic Traction Control cannot control the slip enough even operating in Cut Level 3. Obviously statistically two of four remaining cylinders are still able to overstress both rear wheels. Had to learn this while overtaking a rather slowly car. The situation had some potential for adrenalin, rear wheels took a big step aside, had good luck reacting very fast so I stayed on the road. As a resumee four year old Hankook S1 evo are no good for a car with this potential. So I bought myself something better to get a bit more grip:

[KurtVerbose]

What did you get, can't read the label (I did try turning my laptop upside down)?

[redvts]

Federal 595 rsr

[cs_]

Great tyres! Remind me somehow of the Kumho V70A I used to drive some years ago. Not quite the grip, but near. It's a pure pleasure driving around bends with the Federals, very precise handling. And the traction control only has to work hard in first gear, grip now is appropriate for the high power output of the engine. If you see the old tyres you may understand why I had to change. They had no significant grip anymore. Dangerous driving with 383PS...

[cs_]

One of our members at www.speedsterforum.de found a company to build better gearshift cables. On wednesday I dropped one pair into my VX. What an upgrade! Shifting has never been so easy and precise! Much better quality and they did cost a lot less than the stock ones.

[Aerodynamic]

Last weekend I learned that the Racelogic Traction Control cannot control the slip enough even operating in Cut Level 3. Obviously statistically two of four remaining cylinders are still able to overstress both rear wheels. Had to learn this while overtaking a rather slowly car. The situation had some potential for adrenalin, rear wheels took a big step aside, had good luck reacting very fast so I stayed on the road.

As a resumee four year old Hankook S1 evo are no good for a car with this potential. So I bought myself something better to get a bit more grip:

Those Federal tires, what are they, just std road tires or R-tireds or semi R/road tires?
,Per

[cs_]

Read the specs

[VXT Tim]

What is the tread depth of an rsr? 5 or 7mm

[Frittiersalon]

What is the tread depth of an rsr? 5 or 7mm

7 mm.

My impressions of the RSR. http://www.vx220.org..._gopid__1392535 #52

[cs_]

Won the award for third fastest quartermile car on this years Opel-Speedster-Club Speed Event in Bitburg. First and second were two Garretts with 428PS and 467PS. Best time measured was a 10,552s, mine was a 11,294s. But you have to be careful with these numbers, they are not comparable with other quartermile times because of the setup of the measuring equipment. Driftbox display showed a 12,0s @ 194,8km/h (121mph), evaluation of the data on the PC using driftbox tools revealed a 12,31s. So quite a difference just how you look at it. But I think even a 12,31s is one heck of a time for this small car.

[Nev]

Surely the time triggers at Bitburg will be very accurate? Better than using GPS in a driftbox? 10.5 secs with 467 PS means mine might even be a 10 second car - I hadn't thought that possible with just 550 BHP/ton.

[cs_]

That was no official time measurement. This was just a club having fun with selfmade measuring equipment. Problem is: the first light barrier triggers when the car leaves the barrier. So the quartermile is 402m minus length of car, additionally the car has still a significant starting speed if the timer starts to run. So you cannot compare the times of the Opel-Speedster-Club with the quartermile times acquired at official events at Bitburg Airbase. You would roughly have to add a second to be comparable. So the 467PS really should be a mid 11s car.

[cs_]

Btw. experienced turbo lag right after shifting all the days on the quartermile at Bit. Thought the recirc valves could not cope with the large air mass produced by the NG2 charger. So I ordered a Forge RS. And this one is quite a different league when it comes to lifting the throttle. Now you can hear the turbo slowly spinning down almost free breathing the air around. No feelable lag anymore. It was a bit expensive, but worth the money for my opinion.

[Nev]

Im using a forge valve at the moment, it feels different to the old Bailey one.

[cs_]

Which Forge do you use? I did use a FMCL007PA for 2.000km and it turned out to be too restrictive. The Bailey DV30 then felt a little better, a bit less lag after shifting. But far from being good. On the road there was no real need to change a thing. But on the quartermile it was a pain! So I ordered the Forge RS right after Bitburg and it makes a big difference, has a lot more airflow.

Edited by cs_, 06 August 2012 - 03:34 PM.