Do all turbos require premium?

MBrown

Diamond Member
Jul 5, 2001
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For instance would a 1.8t from an A4 or Jetta need premium or super gas?
 

MBrown

Diamond Member
Jul 5, 2001
5,726
35
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Originally posted by: Fenixgoon
yes. me = 1.8T owner

That sucks...I assume you have an A4 judging from your sig. How is the gas mileage?
 

Fenixgoon

Lifer
Jun 30, 2003
33,350
12,933
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Originally posted by: MBrown
Originally posted by: Fenixgoon
yes. me = 1.8T owner

That sucks...I assume you have an A4 judging from your sig. How is the gas mileage?

99 Passat, but it shares a lot of parts (or at least used to) with the A4.

i get about 29-30 highway. my brother's 02 A4 got closer to 32-33 highway, IIRC.
 

thedarkwolf

Diamond Member
Oct 13, 1999
9,034
127
106
Require? No but its the recommended gas. Most will back the timing/boost down when running on the lower octane crap. Doesn't make a lot of sense to spend the extra cash on the car and insurance for the turbo though and then go and loose a good bit of the added performance. If I remember right the old 80s turbo fords even had a switch on the dash that you could flip when running low octane gas that would cut the boost in half.
 

alfa147x

Lifer
Jul 14, 2005
29,307
106
106
yes
Acura RDX

My parents get 22 - 27 on milage, depends on who is driving
My mom's got a lead foot
and my dad never has to get any were on time...
 

91TTZ

Lifer
Jan 31, 2005
14,374
1
0
Originally posted by: TerryMathews
Originally posted by: MBrown
Is it because of higher compression?

Always. Octane and compression go hand in hand, whether you're talking about forced induction or not.

LOL

For those looking to learn in this thread, forced induction cars usually have a lower compression ratio than naturally aspirated cars.
 

jagec

Lifer
Apr 30, 2004
24,442
6
81
Originally posted by: 91TTZ
Originally posted by: TerryMathews
Originally posted by: MBrown
Is it because of higher compression?

Always. Octane and compression go hand in hand, whether you're talking about forced induction or not.

LOL

For those looking to learn in this thread, forced induction cars usually have a lower compression ratio than naturally aspirated cars.

The physical compression ratio is usually lower, true, but with the addition of the turbo the engine functions as a multistage compressor, so the overall compression ratio between atmospheric conditions to the combustion chamber at the end of the compression stroke is higher. That is why they need higher octane. The more you compress air, the more it heats up, the more it heats up, the more prone to autoignition the mix becomes. Adding an intercooler, turning down the boost, water injection, lowering the compression ratio of the engine, and running higher octane are all measures which are taken to avoid predetonation.
 

91TTZ

Lifer
Jan 31, 2005
14,374
1
0
Originally posted by: jagec


The physical compression ratio is usually lower, true, but with the addition of the turbo the engine functions as a multistage compressor, so the overall compression ratio between atmospheric conditions to the combustion chamber at the end of the compression stroke is higher. That is why they need higher octane. The more you compress air, the more it heats up, the more it heats up, the more prone to autoignition the mix becomes. Adding an intercooler, turning down the boost, water injection, lowering the compression ratio of the engine, and running higher octane are all measures which are taken to avoid predetonation.


This is all true and should be common sense to anyone who owns a turbocharged car. However he said compression ratio, and that has a clearly defined definition.