iS200 Rotrex/Antonov Stage 3
This blog is a continuation of our Lexus iS200 Supercharger Stage 2 Upgrade blog which you can see at
We are mighty proud that our client chose us to deliver his dream of owning the worlds most powerful supercharged Lexus is200 using the original 1G-FE engine. There are more powerful cars around using a different engine or using a turbocharger, but this car really is something very special.
Although we have more experience with Lexus cars than any other company in the UK, when commissioned we knew that we were charting completely new and unexplored territory and so this project was going to be a challenge.
The engine and engine control functions had already been previously uprated as can be seen on the previous blog, so all we had to do was to adapt the Rotrex – Antonov supercharger to the Lexus iS200 and deal with any issues as they arise.
The Rotrex supercharger is a very efficient and compact centrifugal supercharger. The Antonov conversion introduces a 2 speed internal transmission to increase the boost pressure at low engine speeds.
Although Rotrex offer larger superchargers, Antonov had developed their technology only on Rotrex superchargers rated up to 400hp.
Our design brief was to get as close to 400hp with compromising the “Lexusness” of the car, which means that could not produce a car with too much intake or exhaust noise, and we had to retain the smoothness for which Lexus is renowned.
Here are some pictures of the Rotrex – Antonov supercharger installation:
Rotrex supercharger with the compressor housing removed.
Rotrex compressor housing
Rotrex – Antonov supercharger retention cradle manufactured by us.
Another part of the cradle.
Here’s the Rotrex – Antonov supercharger during mock up.
The Rotrex – Antonov supercharger runs on special traction fluid in it’s own remote reservoir.
Here are the mounting brackets after final treatment and installation:
Here’s the final completed installation:
Here’s a short video of supercharged engine with disconnected pressure pipes:
We were very pleased with the final outcome but went onto deal with some normal development and teething issues which are to be expected when breaching new frontiers by creating something that has never been done before.
The first thing we found was that because we had to retain the standard TTE air filter box to minimise the induction noise (which was totally unacceptable with an open induction kit), there was an enormous depression inside the air box (caused by it’s own restriction) which was trying to suck the K&N filter into the supercharger!
This issue was relatively easy to resolve by manufacturing a filter retention mechanism inside the air box.
The next issue became apparent at a Lexus Owners Club day meeting here at Torque Developments. After several hard runs loaded with passengers, the car developed a misfire at full throttle.
The cause of this issue was located after undertaking an exhaust back pressure test on our Rototest chassis dyno. We found that we had 2.5 bar (absolute) of back pressure in the exhaust system!!
This was then quickly tracked down to the catalytic converter which had melted and blocked the exhaust system. Although it was a hi flow racing cat, it was too small for this application, and the standard front pipes were still being used which were too restrictive and generating excessive heat.
Here’s the melted cat internals
This issue was resolved by installing a larger catalytic converter and hi flow down pipes.
The next issue that came to light during daily use of the car was a failure of the standard crankshaft pulley which sheared. Subsequent dyno testing showed that the parasitic losses of the supercharger were significantly higher than we were led to believe, so in hind site the failure of the standard pulley was to be expected.
This issue was resolved by manufacturing a new crankshaft pulley
This is the extent of our development of the Rotrex – Antonov supercharged Lexus iS200 to date.
There was some contention with some people in the UK Lexus Owners Club over our Clients requirement for discretion on the power figure. Of course we intend to honour our clients wishes on this matter but i don’t think he will mind if we reveal that it will produce close to the limitations of the supercharger when the restrictions that provide it’s “Lexusness” are removed.
All in all this is a fantastic car, and we would like to thank our client for choosing us help build it.