Drop in MPH at Track (2018 A10 GT w/ Roush Blower)

[hlfbkd420]

Well.... I had a weird night at the track the other night. Temps and DA were similar to the last time I was there a month previous. Anyway, for the first time ever I put 3 gallons of 100 octane race gas in the car (it had about 7 gallons of 91 in it at the time). Drove it about 5 miles after topping off.

My MPH was off by a crazy amount for all runs. I only drove 20 miles to the track so I don't *think* it was heat soaked. I do not have a way to monitor IAT2.

2018 A10 GT w/ Roush Blower (street tires)
A month ago:
12.2 @ 123mph

Friday night:
12.7 @ 113mph

MPH was almost 10mph lower for ALL runs the other night. Not sure why it was so low. I find it hard to believe the DA or temp would cause a 10mph difference. 60' times were the same. *Could* temp or weather really drop it 10mph? Could the car not like the race fuel and it pissed the ECU off? All of my runs with the blower previous to this have been about 118 to 123mph.

Anyone have any ideas? Also, what should I use to create logs since I know someone will ask if I did.

Excuse my inexperience, first supercharged car ever. Time for a trip to dealer?

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[Jay-rod427]

Weather wouldn't make it drop that much. What race fuel was added? It's not as simple as dump in some 100 octane race fuel. Some have different Stoich rates than others. If the stoich ratio is off from pump gas it will run like crap since the tune uses pump gas tables.

 

[hlfbkd420]

What race fuel was added?

Bought 100 octane from Love's. Not sure on brand, wasn't paying that much attention. Tried a calculator and it looks like 6.7 gallons of 91 and 3.3 gallons of 100 octane would put it at about 93.

Actually, I think it may have been Sunoco gas.

 

[GTFORMULA]

I have noticed that in the past, some of my cars slowed down from too much octane. Strange .

 

[Darkhelmet22]

Both of those times are slower than tuned NA cars. I hate to be the bearer of bad news but this seems to be an issue plagued by lots of the roush blower cars. The blower heat soaks like crazy and the heat exchanger is way too small. It doesn't help the roush tune is garbage. Get a good tune from PBD or Lund and install an ice tank and see what happens. You also could try a can of Boostane since is doesn't change stoich values of the fuel.

 

[Ponderthis]

something is way off... A stock 15-17 can trap 113mph.. That car not making any power for some reason! Maybe you got some 87 octane instead of whatever you thought you were getting.

 

[hlfbkd420]

something is way off... A stock 15-17 can trap 113mph.. That car not making any power for some reason! Maybe you got some 87 octane instead of whatever you thought you were getting.

I know... That's what I was trapping stock..

No chance I got the wrong fuel.. Pump only had 100 and 110.

Unless it was 87 in the station tank...

Both of those times are slower than tuned NA cars. I hate to be the bearer of bad news but this seems to be an issue plagued by lots of the roush blower cars. The blower heat soaks like crazy and the heat exchanger is way too small. It doesn't help the roush tune is garbage. Get a good tune from PBD or Lund and install an ice tank and see what happens. You also could try a can of Boostane since is doesn't change stoich values of the fuel.

For sure.. I read all about the issues well before I made the purchase... I am not good at launching either but that wasn't the problem either..

 

[Angry50]

i cant comment on the heat soak but its possible. I will say 3 gallons of 100 octane added to probably crap 91. be lucky if you got to 93 octane.. plus once you get decent octane it will take a couple of pulls for the care to see the improved octane. and if you just dumped the 100 octane on top it probably didnt mix well enough. get yourself a can of boostane an dump it in before you fill up then head to the track. with that fuel

 

[Teezlr]

More than likely heat soak pulling timing

 

[Greyhorse]

A friend of mine drives a fuel truck, he told me that some of the mom and pop gas stations will over order reg gas on purpose and tell them to dump the rest in the premium tank, im sure most if not all fi cars get gas from reputable national chain gas stations that are top tier listed or i would hope. Do you have the most recent tune? There is a revised tune for the a10 roush kits

 

[hlfbkd420]

More than likely heat soak pulling timing

Maybe. Can you recommend a device to pull logs? I thought at 135 degree IAT2 temps it pulls timing, not sure if a normal device can read that info on a Roush though.

If it was heatsoaked, it did it over a very short drive (15miles). A few weeks before I was a LOT harder on it with multiple back to back 1/4 mile runs and it did this first run the other night. Ambient temps weren't much different (high 60's).

 

[hlfbkd420]

A friend of mine drives a fuel truck, he told me that some of the mom and pop gas stations will over order reg gas on purpose and tell them to dump the rest in the premium tank, im sure most if not all fi cars get gas from reputable national chain gas stations that are top tier listed or i would hope. Do you have the most recent tune? There is a revised tune for the a10 roush kits

I should but not 100% sure. Installed in January. Have never thought the tune was terrible but again, first FI car so it's always fast... Until the track the other night. The device the dealer uses to pull the tune *should* always pull the latest and greatest from what I hear.

I get my gas from Quik Trip most of the time. They are "top-tier" rated but hell, who knows.

 

[Greyhorse]

The roush dealer i took mine too for the update wasnt aware of any revised tune till i told them and they called gave my vin number and said that the guy from roush said mine wasnt up to date, and they are the biggest roush dealers in the country so id definetly check it out

 

[18 Smoke]

Get an Ngauge so you can see what’s happening in real time. A PBD/Lund tune ain’t a bad idea either

 

[hlfbkd420]

I would love to tune but it's my dd. Need that warranty for now

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