Product Review: VRP Pistons

We saw an article on NeoBuggy about a new product from Vision Racing Products, and decided that Sanford and Son RC would do a product review. The new product is an innovative new piston for your 1/10 scale or 1/8 scale RC vehicles. VRP claims that the unique design of their pistons provides a compression stroke similar to stock, but provides a faster rebound stroke. The faster rebound stroke is supposed to allow your buggy to soak up the bumps and ruts better, and make for a quicker weight transfer front to back and side to side, making your buggy more responsive. The quicker rebound stroke is also supposed to make it easier for your buggy to jump farther.

Pistons
VRP rear piston (left), Kyosho rear piston (right)

We contacted Mike Ankey from VRP and requested a set of pistons for our Kyosho MP9 TKI3 1/8 scale nitro buggy. Check the VRP website for your specific application. The pistons arrived a few days later, and we were off to our local track, Heritage RC Park in Chula Vista, CA. I had just raced on this layout the previous weekend, so that would make testing easier.

I ran for about half a tank on the same setup I had used the previous weekend, because I wanted to get the setup dialed in before testing began. The car was still perfect, so no setup changes were needed. I headed back to the pits to prepare.

Pistons
Unique design of the VRP piston provides a faster rebound stroke

The first thing I did was to build up two full sets of shocks. The first set would have my normal Kyosho 1.2×6 front pistons and 1.3×8 rear pistons. The second set of shocks were built with the VRP 1.2×6 front pistons and 1.3×8 rear pistons. (The VRP pistons have two additional holes, covered by a flap, so the 6-hole pistons actually have 8 holes. The VRP 8-hole pistons have 10 holes). Both sets of shocks were filled with Losi 35wt oil in front and 40wt in the rear. A fresh set of AKA Soft Impact tires would be used for each test (a new set for the Kyosho piston test and another new set for the VRP piston test).

I mounted up the shocks containing the Kyosho pistons first, set my ride height and camber, and hit the track. Track manager Gil Alontaga was kind enough to hook up one of the monitors, so recording of lap times would be easy. I ran for about half a tank, to get the motor up to temp and to break in the tires a little bit. I pitted for fuel, and we started the first round of testing. The car was perfect, and I ticked off the laps. I ran 14 laps, and my pit man Larry Sanford recorded 12 of them, throwing out two laps where I had a bobble and a crash.

Pistons
Front shock with VRP piston installed

We headed back to the pits where I mounted up the other set of shocks containing the VRP pistons. I rechecked ride height and camber, and mounted up a fresh set of tires. As in round 1, I ran about half a tank to warm up the motor and tires, and pitted for a full tank. I could tell just from the practice laps that the buggy jumped better. The suspension was also more reactive, as would be expected. A little too reactive for my driving style, but I decided to go ahead and run this round with the exact same setup as round 1. The car took a little getting used to, but as in the first round, I got in 12 good laps as my pit man recorded the lap times. We didn’t do any calculations at the track, but a quick review of the lap times showed that the VRP pistons definitely reduced my lap times. We would wait until we arrived home to make the final calculations.

I wanted to make a small setup change and then make a second run with the VRP pistons. I wanted to calm the suspension down a little bit, so I moved the rear shocks in on the tower one hole. I double-checked the camber and ride height and headed back to the track. The car felt much better. I quickly warmed up the car, because the rain clouds were rolling in. I pitted for fuel and we started round 3 of testing, but we could only get one lap in before it started raining. That one lap was the fastest lap of the day (32.872), so I think we found the perfect setup for the VRP pistons!

Kyosho MP9 TKI3
Our test mule, the Kyosho MP9 TKI3

We headed home and plugged all the numbers into the calculator. As we expected, the lap times with the VRP pistons were better … 0.2 seconds per lap better, on average. Our results are reflected in the chart below (The faster lap times between the two runs are highlighted in green):

Lap # Lap Time (Kyosho Pistons) Lap Time (VRP Pistons)
01 33.826 33.638
02 33.995 33.280
03 33.830 33.457
04 33.894 33.521
05 33.417 32.976
06 33.852 33.247
07 33.541 33.134
08 33.346 33.803
09 33.525 33.458
10 33.652 33.045
11 33.094 33.614
12 32.957 33.358
Avg: 33.577 33.377


In review, we found the VRP pistons to be a definite advantage. The car jumped better, and produced faster lap times. The suspension was more reactive, which some drivers will like immediately. The suspension was a little too reactive for my driving style, but that was easily remedied with a minor setup change. We plan to continue our evaluation in real-world racing conditions. We would definitely recommend that you try these pistons for yourself!

Thank you to Gil Alontaga and Heritage RC Park for their help, and a special thank you to Mike Ankey and the folks at Vision Racing Products.

Update

We attended Round 2 of the Pro-Line Championship Series at Heritage RC Park on May 2, 2015, where we got a chance to use the VRP pistons in real race conditions. Below are the results for Round 1 of the series (using the Kyosho pistons), and the results for Round 2 of the series (using the VRP pistons). The layout was the same for both races. The same engine, and the same type and compound of tires were used for both races. During Friday’s practice the shocks with the VRP pistons felt like they had a little too much pack, so I lightened the shock oil by 2-1/2 wt front and rear. The engine temperature was 227 degrees F after the Round 1 A Main, and 229 degrees F after the Round 2 A Main:

Round 1 results with Kyosho pistons
Round 1 results using the Kyosho pistons (April 18, 2015)

Round 2 results with VRP pistons
Round 2 results using the VRP pistons (May 2, 2015)

Fast Lap, Top 5, 10 and 15 average lap times were all about .5 seconds faster using the VRP pistons. In conclusion, you may want to make some minor setup changes after going to the VRP pistons, but we think you will definitely see quicker lap times.

Lucas Sanford

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