ZR1 Less than 900 RWHP on Dyno, but we found out why
Race Director
Joined: Dec 2006
Posts: 12,353
Likes: 2,891
From: Fort Worth, Texas
dude calm down im simply asking and all youre saying is it cannot be this even though every test ive done shows that is, in fact, this, with no other explanation. i was simply trying to share my experience of troubleshooting by pouring the exact same gas into my GLC63, not sure why you went into attack mode, but whatever. thanks for your "help" i guess. I am interested in finding the solution, but all you say is "bad gas" and then proceed to talk ****. Not sure how that helps at all. The bad gas works in every other car. I was trying to see if anyone else has tried this with their ZR1 to see if there is a problem with using 100 octane somehow since it didn't affect my z06 or Mercedes. I'm so sorry for inconveniencing you, please forgive me.
Melting Slicks
Joined: Aug 2000
Posts: 2,595
Likes: 812
From: Phoenix, AZ USA
VP-MS100 testing
Last edited by JMB; May 14, 2026 at 06:57 PM.
Race Director
Joined: Dec 2006
Posts: 12,353
Likes: 2,891
From: Fort Worth, Texas
Farmer claims he used 98 octane fuel which is a departure from his "typical" hero runs where he uses oxygenated VP-MS100! Not sure why he didn't go oxygenated....I had to prove to his crew that it was worth 50 RWHP!!!
VP-MS100 testing
VP-MS100 testing
Melting Slicks
Joined: Aug 2000
Posts: 2,595
Likes: 812
From: Phoenix, AZ USA
I missed it was higher than normal premium, but wonder if the computer limits torque as he only went a tenth faster than Brooks with a better 60’, DA and CF wheels as well as him being a jockey. I know it can compensate for weather, so wonder if better fuel doesn’t allow it to make any more power and if it’s limiting it by spark that is worse for higher octane.
Race Director
Joined: Oct 2008
Posts: 16,626
Likes: 7,705
From: NJ
No doubt only going to get amplified in a boosted application.
We used to run cans of "race gas" additive in our C7Zs before a rally to make sure we weren't underperfoming when facing off against lambos and Ferraris
it worked. Proven on the dyno. Before and after. They knock and pull timing on pump gas. These boosted hi performance cars are tuned to the edges of pump gas and are VERY conservative near that limit. They pull out quick. The high octane keeps it happy.
We used to run cans of "race gas" additive in our C7Zs before a rally to make sure we weren't underperfoming when facing off against lambos and Ferraris
it worked. Proven on the dyno. Before and after. They knock and pull timing on pump gas. These boosted hi performance cars are tuned to the edges of pump gas and are VERY conservative near that limit. They pull out quick. The high octane keeps it happy.
Racer
Joined: Jul 2016
Posts: 293
Likes: 181
That might be all your read, but that's definitely not all I said. I have been the most invested and helpful poster in regards to your problem, and it wasn't until my last post that I said anything remotely considered "**** talking"
Working theories include (as previously stated)
-Bad gas (lol) to include too high of water content
-Bad gas (lol) to include too high E content
^ both the above will cause a lean condition, ESPECIALLY if injector margin is too low
-Not enough injector or tune margin in the ZR1 to accommodate less than perfect fuel conditions
-Compression ratio too high to accommodate for lean conditions
-Chamber design not tolerant of knock
You other vehicles may have been fine on the fuel for a plethora of reasons. Different quality of fuel at time of purchase, both cars have enough injector to manage higher E content, the Z06 for sure isn't boosted- so it's not dealing with that, chamber designs could be different, tunes are certainly different, load on engines are different... its a long list
100 octane by itself won't cause issues. Airplanes with 8:1 compressions run on 100 octane. The issue lies in how they achieved that 100 octane for your locality, or whether or not the fuel was contaminated with (most likely) water and how the ZR1 handles sub-par fuel conditions
Ways we can actually test this: data log injector duty cycle and compare to a/f ratio, test fuel for water and ethanol content
Either way, if the car knocked that hard- it wouldn't be a bad idea to pull plugs and check the gap. When engines detonate hard enough, they can collapse the strap of the spark plug. Probably been too long now, but another test you could have done would have been to pull a plug and look for speckling on it- another indicator of detonation
[/"**** talking"]
Working theories include (as previously stated)
-Bad gas (lol) to include too high of water content
-Bad gas (lol) to include too high E content
^ both the above will cause a lean condition, ESPECIALLY if injector margin is too low
-Not enough injector or tune margin in the ZR1 to accommodate less than perfect fuel conditions
-Compression ratio too high to accommodate for lean conditions
-Chamber design not tolerant of knock
You other vehicles may have been fine on the fuel for a plethora of reasons. Different quality of fuel at time of purchase, both cars have enough injector to manage higher E content, the Z06 for sure isn't boosted- so it's not dealing with that, chamber designs could be different, tunes are certainly different, load on engines are different... its a long list
100 octane by itself won't cause issues. Airplanes with 8:1 compressions run on 100 octane. The issue lies in how they achieved that 100 octane for your locality, or whether or not the fuel was contaminated with (most likely) water and how the ZR1 handles sub-par fuel conditions
Ways we can actually test this: data log injector duty cycle and compare to a/f ratio, test fuel for water and ethanol content
Either way, if the car knocked that hard- it wouldn't be a bad idea to pull plugs and check the gap. When engines detonate hard enough, they can collapse the strap of the spark plug. Probably been too long now, but another test you could have done would have been to pull a plug and look for speckling on it- another indicator of detonation
[/"**** talking"]
Last edited by chrisM916vette; May 14, 2026 at 10:05 PM.
Le Mans Master
Joined: Jul 2010
Posts: 6,582
Likes: 2,643
From: Lancaster, PA
well if it was bad fuel, it shouldn't be working fine in the Mercedes, right? I mean pretty much the same exact fuel as I filled up fuel containers from the same pump I filled up the car with. I guess I'll try it again and see what happens, but this ONLY happened the one time i filled it halfway with 100 from the pump.
I'm just trying to make sense of what happened. Just because something doesn't make sense it doesn't mean it has no explanation. We may just don't know what it is.
Burning Brakes
Joined: Mar 2009
Posts: 755
Likes: 38
From: USA
dude calm down im simply asking and all youre saying is it cannot be this even though every test ive done shows that is, in fact, this, with no other explanation. i was simply trying to share my experience of troubleshooting by pouring the exact same gas into my GLC63, not sure why you went into attack mode, but whatever. thanks for your "help" i guess. I am interested in finding the solution, but all you say is "bad gas" and then proceed to talk ****. Not sure how that helps at all. The bad gas works in every other car. I was trying to see if anyone else has tried this with their ZR1 to see if there is a problem with using 100 octane somehow since it didn't affect my z06 or Mercedes. I'm so sorry for inconveniencing you, please forgive me.
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Burning Brakes
Joined: Mar 2009
Posts: 755
Likes: 38
From: USA
That might be all your read, but that's definitely not all I said. I have been the most invested and helpful poster in regards to your problem, and it wasn't until my last post that I said anything remotely considered "**** talking"
Working theories include (as previously stated)
-Bad gas (lol) to include too high of water content
-Bad gas (lol) to include too high E content
^ both the above will cause a lean condition, ESPECIALLY if injector margin is too low
-Not enough injector or tune margin in the ZR1 to accommodate less than perfect fuel conditions
-Compression ratio too high to accommodate for lean conditions
-Chamber design not tolerant of knock
You other vehicles may have been fine on the fuel for a plethora of reasons. Different quality of fuel at time of purchase, both cars have enough injector to manage higher E content, the Z06 for sure isn't boosted- so it's not dealing with that, chamber designs could be different, tunes are certainly different, load on engines are different... its a long list
100 octane by itself won't cause issues. Airplanes with 8:1 compressions run on 100 octane. The issue lies in how they achieved that 100 octane for your locality, or whether or not the fuel was contaminated with (most likely) water and how the ZR1 handles sub-par fuel conditions
Ways we can actually test this: data log injector duty cycle and compare to a/f ratio, test fuel for water and ethanol content
Either way, if the car knocked that hard- it wouldn't be a bad idea to pull plugs and check the gap. When engines detonate hard enough, they can collapse the strap of the spark plug. Probably been too long now, but another test you could have done would have been to pull a plug and look for speckling on it- another indicator of detonation
[/"**** talking"]
Working theories include (as previously stated)
-Bad gas (lol) to include too high of water content
-Bad gas (lol) to include too high E content
^ both the above will cause a lean condition, ESPECIALLY if injector margin is too low
-Not enough injector or tune margin in the ZR1 to accommodate less than perfect fuel conditions
-Compression ratio too high to accommodate for lean conditions
-Chamber design not tolerant of knock
You other vehicles may have been fine on the fuel for a plethora of reasons. Different quality of fuel at time of purchase, both cars have enough injector to manage higher E content, the Z06 for sure isn't boosted- so it's not dealing with that, chamber designs could be different, tunes are certainly different, load on engines are different... its a long list
100 octane by itself won't cause issues. Airplanes with 8:1 compressions run on 100 octane. The issue lies in how they achieved that 100 octane for your locality, or whether or not the fuel was contaminated with (most likely) water and how the ZR1 handles sub-par fuel conditions
Ways we can actually test this: data log injector duty cycle and compare to a/f ratio, test fuel for water and ethanol content
Either way, if the car knocked that hard- it wouldn't be a bad idea to pull plugs and check the gap. When engines detonate hard enough, they can collapse the strap of the spark plug. Probably been too long now, but another test you could have done would have been to pull a plug and look for speckling on it- another indicator of detonation
[/"**** talking"]
Race Director
Joined: Dec 2006
Posts: 12,353
Likes: 2,891
From: Fort Worth, Texas
very interesting, I’m going to pull my plugs to check now on my car as I recently filled up with 92 ethanol free and the car under load ran like it had bad fuel. I did order a fuel tester off Amazon and going to check the fuel from the station I pumped at that gave my car issues. You mentioned Avgas, would running that in these ZR1’s be of any advantages? I don’t know a lot about fuels but I do have handy 99 oxygenated fuel by VP and at my work I could fill up as much Avgas as one would want for an extremely reasonable price any time. Thanks!
