Can I start off with a stupid question?
Discussion
Hi guys,
Picked up my 05 VXR last week, been smiling from ear to ear ever since. Certainly is different to my (heavily modified) Astra I had
OK, time for the stupid question Should I use normal or premium unleaded? I would have assumed premium, but the salesman says it runs a lot better on normal(?)
Also, I have seen a lot on here about Wortec exhausts, is there a website or something that I can get an idea of gains, price etc?
(I can't believe I have only had it a week and already looking at mods
)
Picked up my 05 VXR last week, been smiling from ear to ear ever since. Certainly is different to my (heavily modified) Astra I had
OK, time for the stupid question
Should I use normal or premium unleaded? I would have assumed premium, but the salesman says it runs a lot better on normal(?) Also, I have seen a lot on here about Wortec exhausts, is there a website or something that I can get an idea of gains, price etc?
(I can't believe I have only had it a week and already looking at mods
) ONLY USE PREMIUM 97 or more.......imbed that into your psyche!!!!!
www.WORTEC.CO.UK
Welcome to the fold, whereabouts in uk are you ?
www.WORTEC.CO.UK
Welcome to the fold, whereabouts in uk are you ?
GSI Daz congratulations on your aquisition - seems we got here about the same time - picked mine up a week ago tomorrow......only mine's not a VXR....good colour though 
Caspy is standard unleaded ok for the CV8 (04) - the manual suggests it is but I am always happy for someone elses view
Caspy is standard unleaded ok for the CV8 (04) - the manual suggests it is but I am always happy for someone elses view
Cue Me to ask some more silly questions.
AFAIK Lower octane fuels actually have more energy/power than high octane, only they dont resist knock very well. (Longer hydrocarbons)
So the "correct" octane for the car is actually a balance of burn rate, timing, compression and scary stuff like quench, swirl and other stuff.
In summary what is recommended by the manufacturer is usually best. Fuel here is better than in Oz where they have 91 octane stuff and need to step up to Premium95 or Ultra98.
If timing is on the edge lower octane fuel may induce knock retard which will pull timing until the knock subsides then it will ease timing back in to regain full spark advance. We are talking seconds here. If timing has been set to 98 Octane fuels then I can understand you should only use this, this could be the case with a remap etc. Though some guys have adjusted timing and changed octane and picked up no more power.
I think guys with the LS2 which runs near 11:1 compression are probably better of with 98 octane, but Im not so sure about the 10:1 LS1.
Either way you should run the recommended octane for your tune. Factory tune suggests 95 is fine. In fact you can sharpen up the tune and still run the same fuel.
Basically you want to run the minimum timing for max power, too much timing means your cylinder burn is pushing AGAINST the piston stroke and not with it.
Id be interested to hear dyno results etc to compare.
Generally higher compression gains offsets the losses in power due to running higher octane. So overall a higher compression is favoured over the octane rating. But in a stock engine why run less powerfull fuel than you need to?
AFAIK Lower octane fuels actually have more energy/power than high octane, only they dont resist knock very well. (Longer hydrocarbons)
So the "correct" octane for the car is actually a balance of burn rate, timing, compression and scary stuff like quench, swirl and other stuff.
In summary what is recommended by the manufacturer is usually best. Fuel here is better than in Oz where they have 91 octane stuff and need to step up to Premium95 or Ultra98.
If timing is on the edge lower octane fuel may induce knock retard which will pull timing until the knock subsides then it will ease timing back in to regain full spark advance. We are talking seconds here. If timing has been set to 98 Octane fuels then I can understand you should only use this, this could be the case with a remap etc. Though some guys have adjusted timing and changed octane and picked up no more power.
I think guys with the LS2 which runs near 11:1 compression are probably better of with 98 octane, but Im not so sure about the 10:1 LS1.
Either way you should run the recommended octane for your tune. Factory tune suggests 95 is fine. In fact you can sharpen up the tune and still run the same fuel.
Basically you want to run the minimum timing for max power, too much timing means your cylinder burn is pushing AGAINST the piston stroke and not with it.
Id be interested to hear dyno results etc to compare.
Generally higher compression gains offsets the losses in power due to running higher octane. So overall a higher compression is favoured over the octane rating. But in a stock engine why run less powerfull fuel than you need to?
Basically from what I understand running a higher octane than what the engine is configured for may actually reduce your power not increase it.
Not trying to dismiss the requirement for "tuned" vehicles to require higher octane, but just want to understand myself if it is acutally required. After some research and my personal experiences for me on my 10:1 compression LS1 Id say no I dont need to run higher octane. (Plus it costs more)
Here are some references
http://ls1-australia.com/forum/viewtopic.php?t=507
http://ls1-australia.com/forum/viewtopic.php?t=519
"The important thing to remeber about fuel octane is that is the engine will make the best power on the min octane that the engine requires."
This one is quite good www.bajajusa.com/Who%20Needs%20High%20Octane%20Fuel.htm
And from here http://extension.usu.edu/files/factsheets/aska3.htm
"Purchase gasoline with the appropriate octane rating. Follow the manufacturer's recommendations when selecting fuel. If your car does not require a high octane fuel, hundreds of dollars can be saved each year by purchasing the lowest grade (octane) of gasoline. If your engine does not knock or ping when a lower octane fuel is used, changing your buying habits will save money."
And here http://autorepair.about.com/od/generalinfo/a/aa06050
"Should You Ever Switch To A Higher Octane Gasoline?
A few car engines may knock or ping — even if you use the recommended octane. If this happens, try switching to the next highest octane grade. In many cases, switching to the mid-grade or premium-grade gasoline will eliminate the knock. If the knocking or pinging continues after one or two fill-ups, you may need a tune-up or some other repair. After that work is done, go back to the lowest octane grade at which your engine runs without knocking."
>> Edited by ringram on Thursday 29th December 21:02
Not trying to dismiss the requirement for "tuned" vehicles to require higher octane, but just want to understand myself if it is acutally required. After some research and my personal experiences for me on my 10:1 compression LS1 Id say no I dont need to run higher octane. (Plus it costs more)
Here are some references
http://ls1-australia.com/forum/viewtopic.php?t=507
http://ls1-australia.com/forum/viewtopic.php?t=519
"The important thing to remeber about fuel octane is that is the engine will make the best power on the min octane that the engine requires."
This one is quite good www.bajajusa.com/Who%20Needs%20High%20Octane%20Fuel.htm
And from here http://extension.usu.edu/files/factsheets/aska3.htm
"Purchase gasoline with the appropriate octane rating. Follow the manufacturer's recommendations when selecting fuel. If your car does not require a high octane fuel, hundreds of dollars can be saved each year by purchasing the lowest grade (octane) of gasoline. If your engine does not knock or ping when a lower octane fuel is used, changing your buying habits will save money."
And here http://autorepair.about.com/od/generalinfo/a/aa06050
"Should You Ever Switch To A Higher Octane Gasoline?
A few car engines may knock or ping — even if you use the recommended octane. If this happens, try switching to the next highest octane grade. In many cases, switching to the mid-grade or premium-grade gasoline will eliminate the knock. If the knocking or pinging continues after one or two fill-ups, you may need a tune-up or some other repair. After that work is done, go back to the lowest octane grade at which your engine runs without knocking."
>> Edited by ringram on Thursday 29th December 21:02
ringram said:
This one is quite good www.bajajusa.com/Who%20Needs%20High%20Octane%20Fuel.htm
at first but... that one really is a good one on explaining it. We have mapped over 70 Monaro/HSV etc. and this is my recommendations based on extensive datalogging.......
2004 CV8 untuned use 95 for best results but will run on 92.
2004 VXR untuned use 97 for best results but will run on 95.
2005 CV8 untuned use 97 for best results but will run on 95.
2005 VXR untuned use 97 only............shows bad knock on 95!!!!!
After a Wortec re map it is best to use 97+ for best results but cars will run safely
on 95 but you will lose 10-12hp.
I use 99 in my HSV (special map written for it) and have seen good results in forced induction cars but standard cars won't get any real benifits, but it is a good price...........
2004 CV8 untuned use 95 for best results but will run on 92.
2004 VXR untuned use 97 for best results but will run on 95.
2005 CV8 untuned use 97 for best results but will run on 95.
2005 VXR untuned use 97 only............shows bad knock on 95!!!!!
After a Wortec re map it is best to use 97+ for best results but cars will run safely
on 95 but you will lose 10-12hp.
I use 99 in my HSV (special map written for it) and have seen good results in forced induction cars but standard cars won't get any real benifits, but it is a good price...........
Gassing Station | HSV & Monaro | Top of Page | What's New | My Stuff