Result of Unleaded v Optimax
Discussion
Completely un-scientific but tried over about 800 miles.
Picked up car (Chimaera 4.0HC 94) early Feb fueled up with Tesco unleaded to get home - car ran fine with no roughness at idle or slow through town. From then on Optimax only and gradual deteriation in slow running with gearbox shunting etc at low revs though fine at higher revs and speeds - never awful but it was there.
Last couple of tank fulls gone to Shell unleaded and smooth idle etc has returned and no gearbox shunting - higher revs and speeds fine with no noticeable deteriation in performance.
I know Optimax gives better performance (and is therefore a good idea for track days where the difference may be noticeable) overall but is it the correct choice for everyday driving? I was told by someone experienced with TVRs that normal unleaded is perfectly adequate for everyday running (but of course we all want to put "the best" in our cars don`t we?!).
I know the stepper motor is often mentioned for cases of rough running, but if my experience is anything to go by, it may be worth trying the fuel first.
Picked up car (Chimaera 4.0HC 94) early Feb fueled up with Tesco unleaded to get home - car ran fine with no roughness at idle or slow through town. From then on Optimax only and gradual deteriation in slow running with gearbox shunting etc at low revs though fine at higher revs and speeds - never awful but it was there.
Last couple of tank fulls gone to Shell unleaded and smooth idle etc has returned and no gearbox shunting - higher revs and speeds fine with no noticeable deteriation in performance.
I know Optimax gives better performance (and is therefore a good idea for track days where the difference may be noticeable) overall but is it the correct choice for everyday driving? I was told by someone experienced with TVRs that normal unleaded is perfectly adequate for everyday running (but of course we all want to put "the best" in our cars don`t we?!).
I know the stepper motor is often mentioned for cases of rough running, but if my experience is anything to go by, it may be worth trying the fuel first.
_DJ_ said: Super unleaded or regular? Perhaps your particular engine has been setup to run on regular unleaded and therefore the effect of a fuel with higher RON isn't as you'd expect?
Regular unleaded - it did cross my mind that perhaps using Optimax might need the engine being tweaked but would that really be the case?
It could be. The timing is altered for different types of petrol so if it's set for standard unleaded the extra "bang" from the Optimax could be working at the wrong point in the stroke. Ask your mechanic next time it's being looked at if he can check what it's been set to run on.
iandbeech said:
_DJ_ said: Super unleaded or regular? Perhaps your particular engine has been setup to run on regular unleaded and therefore the effect of a fuel with higher RON isn't as you'd expect?
Regular unleaded - it did cross my mind that perhaps using Optimax might need the engine being tweaked but would that really be the case?
Fish speaking:
My T350 definately runs better on the higher octane Optimax with any lower rev pinking disappearing when the engine is hot.
Optimax is 98.6RON wheras Super is only 97RON. I therefore never pay the higher price for Super as it isn't worth it. As has been mentioned the effect will depend on the tune of your engine as TVR engines have no Knock sensor and thus can't adjust timing automatically for the fuel used.
My T350 definately runs better on the higher octane Optimax with any lower rev pinking disappearing when the engine is hot.
Optimax is 98.6RON wheras Super is only 97RON. I therefore never pay the higher price for Super as it isn't worth it. As has been mentioned the effect will depend on the tune of your engine as TVR engines have no Knock sensor and thus can't adjust timing automatically for the fuel used.
I don't know who said that TVRs run fine on plain unleaded as the truth, especially with the Rover engines is far from it. The Rover based cars are designed to run on Super fuel and should be adjusted to run on plain unleaded.
Gone through this in detail in the bible and on the unleaded FAQ on my website which quotes the appropriate TVR bulletins.
Steve
www.tvrbooks.co.uk
Gone through this in detail in the bible and on the unleaded FAQ on my website which quotes the appropriate TVR bulletins.
Steve
www.tvrbooks.co.uk
Mr Heath, he speaks the truth!
If you still have the sticker next to the fuel filler cap on the Rover V8 models you will specifically see that the car is designed to take SUPER Unleaded fuel only. Yes, you can run it on ordinary Unleaded, but you will pay a performance penalty and potentially rough running damage (though unlikely really).
So 97 / 98 RON it is then. Mine has had the timing knocked back to cope with Unleaded without any problems. However, it runs much smoother and easier on Super and even better on Optimax. Although you can run it on Unleaded, it is better to run the RV8 engines on super (unless you have had the timing adjusted). The newer engines are different, but I suspect that they are similar in that they prefer Super....
Cheers,
Paul
If you still have the sticker next to the fuel filler cap on the Rover V8 models you will specifically see that the car is designed to take SUPER Unleaded fuel only. Yes, you can run it on ordinary Unleaded, but you will pay a performance penalty and potentially rough running damage (though unlikely really).
So 97 / 98 RON it is then. Mine has had the timing knocked back to cope with Unleaded without any problems. However, it runs much smoother and easier on Super and even better on Optimax. Although you can run it on Unleaded, it is better to run the RV8 engines on super (unless you have had the timing adjusted). The newer engines are different, but I suspect that they are similar in that they prefer Super....
Cheers,
Paul
When I picked up my Chimaera 4.0HC from a main dealer 2 and a half (&20k miles) ago I was told Super UL was best but it would run perfectly well on ordinary UL except possibly on a hot day or if driven hard. Seems ok to me on ordinary, you do occasionally get a bit of transmission shunt at LOW revs but otherwise fine.
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