Power loss at track

[tjyyzacc]

I agree, I also had no problems when the car was stock, but I just couldn’t leave it alone. ?

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[Nytrajin]

Have you tried opening a support ticket with PTF? If stock doesn't have an issue they need to have a second look at their ots maps.

 

[tjyyzacc]

I didn’t bother following up with anyone other than my local tuner. I couldn’t find anyone else who seemed to be having the same problem with this tune at the time, so I assumed it was a cooling issue. I threw some money at it in the form of Koyo rads and a meth injection system which I just ran water through exclusively. However, since I now know it’s not a cooling issue I think I’ll invest in an Ecutek tune that incorporates a meth option.

 

[Sikh_Supra]

I didn’t bother following up with anyone other than my local tuner. I couldn’t find anyone else who seemed to be having the same problem with this tune at the time, so I assumed it was a cooling issue. I threw some money at it in the form of Koyo rads and a meth injection system which I just ran water through exclusively. However, since I now know it’s not a cooling issue I think I’ll invest in an Ecutek tune that incorporates a meth option.

I had that problem but it hasn’t happened in a while I was stuck at 270 hp/TQ my tuner couldn’t explain why. Dropping it off this week maybe he can replicate it and find a fix. I currently have stage 4 cooling from CSF race and a pure 800 with the meth injection. Getting port injection done next week as well.

 

[YellowJacket]

that's interesting and reminds me of old 350z issue. They used to get fuel starvation issue just below 70% full tank. we used to joke about that...

just an FYI, stock Supra does not have this issue as I do run on track 'til 1 bar left on the gauge.

I did a lot of seat time in a 350z and don't remember this issue...BUT i did have this issue in my 370z.

 

[Benjilis]

I'm on an ECUTEK stage 1 tune and have the same problem. 2-3 laps then its heat soaked and I notice a huge drop in power. No codes. Going from hitting 130 on the straight to barely hitting 120mph. I run open track events and usually get about 30 mins between sessions and so I don't really get much time between sessions to cool down. After this I removed the center grill since the bottom portion is blocked off in order to allow the engine to warm up faster in colder climates, but is bad for the track. Will be testing it out again this weekend in 90 degree weather to see if there are any improvements.

Heat soak won’t occur if you run an e30-50 blend. Sure you’re not tuned for it so you won’t experience drastic gain. But your IAT will remain stable

 

[zrk]

Heat soak won’t occur if you run an e30-50 blend. Sure you’re not tuned for it so you won’t experience drastic gain. But your IAT will remain stable

The fuel you use has little to do with it getting hotter and hotter under the hood of your car, track conditions, humidity and temperature outside. This just isn't right.

 

[Benjilis]

The fuel you use has little to do with it getting hotter and hotter under the hood of your car, track conditions, humidity and temperature outside. This just isn't right.

Google

 

[OneTimeAccount]

I ran into a fuel starvation issue on track last week. Had 2 bars left and it went into limp mode after a higher speed right hand turn. No codes thrown, just a warning about reduced power. Restarted car and all was good. Reached out to Jackie Ding and he said that it’s common and the tank needs to be at half or higher.

 

[wheeliedub]

Google

I had to do some reading on this myself. While yes, e85 has shown to lower IATs, ZRK is right. “Heat soak” encompasses a lot more than just IATs (everything under the hood). Fuel alone is not going to prevent heat soak.

https://www.team-bhp.com/forum/atta...ervoir-after-i-switch-off-engine-heatsoak.pdf

 

[zrk]

Google

I'd be happy to read some research that proves E85 in your car will cool off your engine bay, but the close thing I can find to the evaporation/cooling rate of E in your take appears to apply to internal engine temperatures, which of course makes sense. Which in turn will cool off your engine bay.. maybe a degree or two. But, as you know, heat soak comes from a LARGE variety of factors.

If it's 105 degrees ambient on the track, it's certainly not going to lower your IATs to a reason place.

ΔT = (Lv/cp,a)/AFR

where cp,a ~1 kJ/kg.°C is the constant-pressure specific heat of air, and AFR is, as you know, the air-to-fuel ratio. This is how I determined the numbers I gave to Eric B.

For E85, I calculate Lv = ~770 kJ/kg and AFRs = 9.8. (AFRs = stoich air-to-fuel ratio). So for an equivalence ratio of 1.25, (equiv ratio = 1/lambda), the change in charge temp would be,

ΔT = 770/(9.8/1.25) = 98.2 °C

To convert to a change in temperature in °F, multiply by 1.8, (but don't add 32!), so 178 °F, which is what you got.

In a DI engine, all that temp drop will occur within the cylinder. In a port injected engine, however, the fuel pools up behind the intake valve, where it will start to evaporate and cool the air within the intake manifold, which is where your IAT2 sensor is located. But since it does not all evaporate there, your computer won't "see" the full effect. Most of the evaporation will be within the cylinder, in fact. Additionally, this air charge cooling is somewhat mitigated by the fuel coming in contact with various metal surfaces, which is shown/discussed in the MIT paper you referenced. (Nice paper, by the way. As an aside, I would direct people to Table 5.1 on p. 30, which compares energy content of the fuels. It clearly shows that ethanol does not contain more energy than regular gasoline.)

So yes, the charge cooling effect of alcohol fuels is quite significant, and greatly helps reduce the risk of detonation. (Its energy balance, etc., are another matter.)

And this math actually checks out quite well.


There's also an MIT white paper linked in the thread. I didn't fully read it, nor did I check the sources, so consider it trash until you do, but this paper seems to imply that fuel type in a forced induction engine will not prevent heat soak. I also didn't check the math I did read in the paper, so again, assume that it's trash until one of us confirms it.

 

[Benjilis]

I'd be happy to read some research that proves E85 in your car will cool off your engine bay, but the close thing I can find to the evaporation/cooling rate of E in your take appears to apply to internal engine temperatures, which of course makes sense. Which in turn will cool off your engine bay.. maybe a degree or two. But, as you know, heat soak comes from a LARGE variety of factors.

If it's 105 degrees ambient on the track, it's certainly not going to lower your IATs to a reason place.



And this math actually checks out quite well.


There's also an MIT white paper linked in the thread. I didn't fully read it, nor did I check the sources, so consider it trash until you do, but this paper seems to imply that fuel type in a forced induction engine will not prevent heat soak. I also didn't check the math I did read in the paper, so again, assume that it's trash until one of us confirms it.

Thanks for the info. I think I thought heat soak is equivelant to IAT.

 

[Rocksandblues]

Can’t comment on the math. But even if e85 is cooler, you are burning more of it and creating more hp. Would think( and in my case) engine is even hotter w another 100 hp

 

[sddz6269]

Do you get this code when the car shuts off the power? (10D000: - Engine torque limit active)

Hi Darth, I got exactly the same code when my car shut off the power. Have you managed to find out the reason?

 

[Vimugsy011]

I believe the heat soak or power loss is normal on these cars when tuned. I run into the same issue at the dragstrip if I make too many runs back to back. I have heard that detuning your car for the courses is probably the best route, turn it down a little as you probably don't need that much power for most of the track. BM3 has options for max cooling I think as well, never used it though.

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