I struggle to understand what to do with MG Reds on a cold, low-grip track.
We have recently changed from Dunlop DFH to MG Reds.
Low HP Class (Comparable to LO206) and @ 160KG MAW
I’ve been racing for around two years and am pretty quick – I am battling with two guys who have been at it for 10-20 years, both of which have national and regional titles.
Heat 1, 9 laps: started with cold pressures at around 14 PSI (with stagger around the kart). I finished P2, and P1 was just so much faster than me in the first few laps and won by 2 seconds. I did end up doing the fasted lap towards the end.
Heat 2, 9 laps: kept the cold pressures around the same, with a slight adjustment. Similar result to heat 1, except lapped traffic caused an incident. Had nowhere to go so went off track and fell back. Before that I was losing time to P1 early in the race.
Heat 3, 9 laps: Kept the cold pressures around the same, with a slight adjustment. This time finishing 3rd. Did the fastest lap again, albeit towards the end of the race.
After heat 3 I talked to the guy who came 2nd; who has been karting for around 20 years. He said he put his tyres up to 20PSI!
Heat 4, 9 laps: After talking to the guy who went up to 20PSI, I then went out on around 16 PSI, this time taking back the 2nd place… but still around 2 seconds off 1st place though took the fastest lap again…
Final, 9 laps: Given the previous results, I went even higher with the pressures, with the inside being 16.8 and then the outside being 16.1… the same problem though. P1 built a 1-2 second lead early on and I could only start winding it back in after lap 5. Set the fastest lap again.
I presume the guy who came P1 was starting even higher than 16-17, maybe 18 or 19? Despite the high pressures, the times we were doing were not far off the lap record so it wasn’t slowing us down time.
Thoughts? Are there other people at the pointy end of the field running such high cold pressures in low HP karting on MG Reds?
You’re too low. The guy who told you 20 probably wasn’t lying. At Dousman we’ve been 20+ since the repave last year. Even when the grip level has increased this season we have still been near that at times.
Too low. Different track surfaces and different compounds will have different target pressures.
We have run the new compound MG/Evinco anywhere from 10-12 to 18-22 depending on track surface and temperature.
Ran a club race at a track in our area 2 months ago, mid to upper 80s and sunny, so plenty of track temp. Started at 12, then went to 14, ended the day at 17-18. Went from 2 second off the pace to being the second fastest kart on track at only 0.2 tenths off the leader pace. It made that big of a difference.
Same track last weekend another club race. Even on a warm sunny Texas day we were still running 17-20 psi range. We were P1 on the day, so the crazy high pressure worked.
Locals say that the asphalt there likes higher pressures.
Also, your data is telling you a story. You set fastest lap, but right at the end. That is great for qualy, but not what you usually want for race. Usually you want to be setup where you strike a balance of tires coming in earlier, but not so early that they fall off badly before the end. You want to optimize how long those tires are at the peak during the race. If they come in at the end, you have left something on the table on your overall race pace. Sometimes you choose to setup to come in very early to be fast when everyone is bunched up and then just hang on till the end.
You can see your lap time trends and they will tell you.
Thanks guys! Went for a hoon with the above two days ago (Clear/Dry Day, 10AM, Winter, Southern Hemisphere).
Started on 22PSI. Kart came in quicker obviously and kept getting faster and faster. Bought it in to measure the delta over a normal race length to calculate the stagger.
Next, I went even higher, starting on around 25PSI. Kart came in 2 laps faster and kept getting quicker and faster with each lap. I was expecting the kart to start hopping towards the end but no, it was on rails…
At Dousman early in the year I would start at 18 and go higher every session and the kart would never go away. I was doing 25 lap stints at 24 psi with no fall off.
After a few big races there laid rubber down, we were down to around 15 psi and the kart and track were acting more normal.
Lesson is, these tires can work at many pressures depending on track condition. Technically you are shooting for a certain tire temp rather than pressure. So whatever it takes in terms of pressure to get that rubber to the right temp so it has some grip.
