The Acura Integra Street / Track car project continues to roll and we are continuing with the theme of making incremental changes to seeing the results at the track. A quick recap of the first 2 parts showed us taking a stock 2001 Acura Integra LS to the track with the most basic changes possible (front brake pads and high temp brake fluid) and enjoying the day with it. Part 2 included street friendly suspension parts that picked up over 2.5 seconds of lap time. Part 3 was planned to be a slight increase in power with an intake/header/exhaust setup but our Instagram community spoke and the choice became a MFactory Helical LSD. This change peaked our interest as we had never actually tested just a differential change on any of the cars that we have used at the track over the years.
Our test track, The FIRM in Starke, FL comprises of mainly 3rd-4th gear type corners and speed but has 1 tight hairpin that sees the transmission shifted down to 2nd gear and even the stock Integra B18b horsepower has trouble planting the tires coming out of that corner so that is where we expected to see the most gain if any at all. We chose to use a MFactory Helical LSD (Limited Slip Differential) for this project as the car will still be enjoyed on the street quite often and if you have any experience with the metal plate type LSD's you know they can be noisy at times. Yes, we do believe the 1 way metal plate LSD's would offer better track performance from our personal past experience but as this car is a jack of all trades the streetability characteristics won out in our decision.
The installation went smoothly as it was just a simple remove OEM open differential and install MFactory LSD process. Although it was tempting to do something like a lightweight flywheel during this process as we had the transmission out of the car it was important to us to allow the LSD to be the only change that we made for an accurate comparison. MFactory recommends using either OEM Honda MTF or Torco MTF. We used fresh OEM Honda MTF.
The first 2 sessions of the day had us running consistent laps times right at our previous personal best (mid 1:27 second range). The MFactory LSD did a good job getting the power to the ground out of the tight hairpin and it was noticeable from the first couple of laps on the track. As the morning went on the LSD provided loads of confidence to be able to get on the power as early as possible coming out of corners which lead to higher speeds between corners and thus improving on the lap times. The best lap for the day ended up at 1:26.4. Just over 1 second quicker than the last test day by only changing to a LSD.
"From the driver seat I can comment that I give the time difference edge to about 0.5 seconds from simply changing to a LSD from a direct performance advantage and 0.5 seconds from the confidence that is inspires in your head to be able to get on the throttle earlier out of corners." (James Innes)
Overall this was a great test and day at the track. We logged just over 100 track miles again and had to do nothing to the car other than add gas. We are onto our next step of the project and based on what we have seen so far we are going to again attack the suspension and go into a more performance oriented coilover to rid the car of body roll. The front tires are still wearing extremely poorly on the outer edges. This is caused by both excessive body roll and/or not enough camber. We are set at 2.5 degrees of negative camber in the front currently and could slow tire wear by increasing the camber but at the same time that will increase the wear rate of the inside of the tires during normal street driving. The plan is to put on some coilovers that will have a higher spring rate and better dampening and then increase the front camber to -3.0 degrees.
We hope to be back at the track for this test in January 2019.
Current Lap Time Results (at The FIRM in Starke, FL):
Stock 2001 Acura Integra LS, Dunlop Direzza DZ102 Tires – 1:36.3
Stock 2001 Acura Integra LS, Bridgestone RE71r Tires – 1:30.2
2001 Acura Integra LS, Suspension Mods – 1:27.5 - (Eibach Pro-Kit Plus, Koni Orange Shocks, Camber Kits, Aligned, RE71r Tires)
2001 Acura Integra LS, Suspension Mods, MFactory Helical LSD - 1:26.4