Loss of Power on Track

[bnightstar]

So on Friday was my first day out with the car for the season. But after the first session my straight speed dropped 10 km/h.

My Best Lap for the day (22 celsius air)

My Best lap from November (11 celsius air)

As you can see I'm down almost 10 km/h on the longest straight.
The car was feeling slow to pull on the straight. At the first session I was hitting 179 but not after that (I suspect is a temperature issue).
Car didn't trow errors and the CHT temps were no more than 113 celsius (235F).
Any ideas what may be wrong ?

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[NightmareMoon]

So on Friday was my first day out with the car for the season. But after the first session my straight speed dropped 10 km/h.

My Best Lap for the day (22 celsius air)

My Best lap from November (11 celsius air)

As you can see I'm down almost 10 km/h on the longest straight.
The car was feeling slow to pull on the straight. At the first session I was hitting 179 but not after that (I suspect is a temperature issue).
Car didn't trow errors and the CHT temps were no more than 113 celsius (235F).
Any ideas what may be wrong ?

Its more likely you didn't get a good exit from the corner. Maybe the tires were overheat or over pressure causing your corner exit to be worse, or perhaps the driver was trying too hard and making mistakes.

Post a screenshot from the later slower lap. Nobody can diagnose anything without a proper comparison.

Is the car stock? What tires?

 

[DonnieO]

Do a compression test

 

[EFI]

What was your oil temp?

Look at your corner speeds. You were carrying more speed on the bottom graph, which could translate to even more speed at the top. 3km/h exit speed could turn into 6-7km/h at the top end.

 

[bnightstar]

Do a compression test

I don't think there is anything wrong with the engine as on the other parts of the track I'm accelerating hard enought. Looks like just my top end RPMs have a problem. Car was running Ruff and cut out before that session. But in the next sessions my straight line speed dropped all the way to 170 km/h.

 

[bnightstar]

What was your oil temp?

Look at your corner speeds. You were carrying more speed on the bottom graph, which could translate to even more speed at the top. 3km/h exit speed could turn into 6-7km/h at the top end.

I didn't record my oil temp but the TrackAddict say my ECT was 210 degrees during that lap in particular. Also notice the straight before the last corner there my speed is higher from lower speed. I'm losing power only at the top end of the RPM range. May be just a driver error but this was consistent till end of day. CHT were up to like 235 degrees.

 

[bnightstar]

Its more likely you didn't get a good exit from the corner. Maybe the tires were overheat or over pressure causing your corner exit to be worse, or perhaps the driver was trying too hard and making mistakes.

Post a screenshot from the later slower lap. Nobody can diagnose anything without a proper comparison.

Is the car stock? What tires?

Here is from another session later in the day. Better exit than both previous laps but still lower speed at the end of the straight.

Car is on 275/35 TW240 semi slick tires, with GLoc R10/R8 break pads, KB Jacking Rails, Steeda Camber Plates, Steeda Front Sway Bar on the 3rd hole from soft and in this case the tires were under inflated. I don't see how this is related to top end speed but I'm not loosing traction.

 

[NightmareMoon]

Here is from another session later in the day. Better exit than both previous laps but still lower speed at the end of the straight.

Car is on 275/35 TW240 semi slick tires, with GLoc R10/R8 break pads, KB Jacking Rails, Steeda Camber Plates, Steeda Front Sway Bar on the 3rd hole from soft and in this case the tires were under inflated. I don't see how this is related to top end speed but I'm not loosing traction.

yeah might not be related. Could be old coils/spark plugs or a fuel filter issue? Compression test isn’t a bad idea but if it only happens under full tilt boogie at high RPM thats a cue (of some sort)

 

[bnightstar]

yeah might not be related. Could be old coils/spark plugs or a fuel filter issue? Compression test isn’t a bad idea but if it only happens under full tilt boogie at high RPM thats a cue (of some sort)

It was warm day so I guess it’s just heat / timing issue but tomorrow car will be at dealer for some work so will do compression test as well.

 

[TeeLew]

So on Friday was my first day out with the car for the season. But after the first session my straight speed dropped 10 km/h.

My Best Lap for the day (22 celsius air)



My Best lap from November (11 celsius air)




As you can see I'm down almost 10 km/h on the longest straight.
The car was feeling slow to pull on the straight. At the first session I was hitting 179 but not after that (I suspect is a temperature issue).
Car didn't trow errors and the CHT temps were no more than 113 celsius (235F).
Any ideas what may be wrong ?

You've definitely got something going on. You're also 10+ K down on the short shoot (119.1 vs. 129.7) after the long straight. Air temp will have an effect, but it shouldn't be that large. It's not wind, because that would help one direction and hurt the other. Do you think you could have gotten a tank of bad gas?

 

[NightmareMoon]

Is it throwing any codes?

 

[bnightstar]

Is it throwing any codes?

It's not trowing any codes checked it on the track car is fine with codes. Last year in July the speeds were similar I guess It's just warm and car is pulling timing. Which is reducing the power after that in Winter car run good. Looks like I will need to think about cooling out the car in summer. Maybe grill delete and a hood :?

 

[bnightstar]

You've definitely got something going on. You're also 10+ K down on the short shoot (119.1 vs. 129.7) after the long straight. Air temp will have an effect, but it shouldn't be that large. It's not wind, because that would help one direction and hurt the other. Do you think you could have gotten a tank of bad gas?

Yeah that's a possibility but I always buy fuel from the same Shell station and it's always V-Power premium 100 RON. I really think it's just timing / overheating issues as my ECT is at the 200F and more during some laps. And my CHT was around 235F

 

[c_reber]

I notice similar speed drops when my car is hot (not overheating, but certainly hot). 1st and 2nd lap of the session straightaway speeds are about 3-6 miles per hour higher than 4th or 5th session. When I glance down at the oil temp gauge, it is at the "yellow".

I don't think it's any big issue, but I think it's time to look into cooling mods, like better vents for the hood. I'm looking at the trackspec for the 2 outside stock vents, and maybe the middle vent also (just not sure I want to cut up my hood yet).

 

[bnightstar]

I notice similar speed drops when my car is hot (not overheating, but certainly hot). 1st and 2nd lap of the session straightaway speeds are about 3-6 miles per hour higher than 4th or 5th session. When I glance down at the oil temp gauge, it is at the "yellow".

I don't think it's any big issue, but I think it's time to look into cooling mods, like better vents for the hood. I'm looking at the trackspec for the 2 outside stock vents, and maybe the middle vent also (just not sure I want to cut up my hood yet).

I go through the whole 44 pages Cooling tread but didn't see this part mentioned anyware:

https://kennybrown.com/collections/cooling-s550/products/mustang-triple-pass-aluminum-radiator

Have a friend of mine with GT350 install it and report great success however he also installed trackspec hood vents. I kind of don't want to go into the whole grill delete/ hood vents game.

Will probably get a CAI (my car is still stock) and the Tripple Pass Radiator and see how it goes.

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