ATS Improved S4S - 93+ Octane Fits 89-95 Chargecooled cars

ATS Racing is finally releasing our first chip/ecu tune. This is based off the latest S4S file with the following improvements:


Lower cooling fan operating temps - turns the fans on 6°C sooner. No reason to wait until 93°C.

Slight change to the overboost conditions.

NO CHANGE to the S4S boost target or duty cycle settings. 

NO CHANGE to ECU safety protocols such as igntion timing retard when knock is detected.

Optimized fuel and timing maps. This chip is for mildly modified Lotus Esprits from SE to S4S and 93 octane fuel. If you live in an area unable to get 93 octane fuel we recomend BOOSTane octane boost or VP Racing Octanium (in that order). 


The following modifications are recommended:




electric intercooler pump

ram air (this is a free modification that bypasses the factory intake resonator)


Price includes chip and MEMcal adapter. No permanent modifications required. You can remove chip and return to your original tune in minutes.


More power from 3700rpm all the way to redline, significant improvement in the midrange and top end. +11whp and +16ft-lbs of torque over the S4S code. 21 additional wheel horsepower and 33ft-lbs additional torque at 4500rpm! Based on our dyno results from a 100% stock 1989 Lotus Esprit SE we feel Lotus used a 15% drivetrain loss when calculating horsepower. In other words, our test car, a 1990 Lotus Turbo with the recomended modifications, is making 330 flywheel horsepower. 


Graph key:  Blue line is ATS improved code, red line is S4S code, green line is SE code. First graph is wheel horsepower and torque, second is wheel horsepower only, third is torque only. 




Horsepower only:


 Torque only:



Personal rant - I spent years building a definition file that allows me to view the code and changes to the code. I've seen the competition. They are not on our level. They don't even have dyno graphs, just random guesses at how much power their work adds. None of the aftermarket chips I have tested have any changes to the fuel or timing maps despite advertising that they do. Well, I take that back, one manufacturer did change the fuel map, but only in a meaningless spot (in other words he wanted it to look changed, but actually do nothing). The rest of the lot just change the target boost setting and base duty cycles of the wastegate solenoid. This chip/tune is the absolute best on the market for a stock turbo/stock fuel system Lotus Esprit. We tested this thing with multiple back to back dyno pulls. Got everything hot and never saw the ECU pull more than 1 degree of igntion timing. We use the Mastertech scan tool to watch ECU outputs and make sure it's always "happy."




Price: $400.00

Shopping Cart

Your cart is empty