# 87 vs. 93 timing logs for 3.6 VR6 - here you go



## KarstGeo (Jan 19, 2018)

This question comes up all the time. Here's some data to answer the question vs. urban legend/internet BS if anyone is interested/understands logging, here are 2 logs from my 3.6 Atlas. First is using 87 and second is using 93. Same WOT 2-3 gear pull. Similar ambient conditions. I logged using my OBDEleven and logged RPM, timing, timing correction/retard, and intake/ambient temp. Clearly there is more timing correction/pull/retard using 87 but the better question to ask is...does it really matter for the average person just driving around town and would most folks even notice? No. Do you make more power on 93? Yes. How much? Probably 5 hp. I'll keep using 87 to putz around. If I was towing, going offroad, or in the mountains, I'd probalby use premium for those times. Science.

https://datazap.me/u/karstgeo72/atlastiminglog9306052020?log=0&data=1-3-4-5-7-8

https://datazap.me/u/karstgeo72/atlastiminglog8705082020?log=0&data=1-5-7-8-9


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## mdtony (Mar 3, 2008)

Good information, thank you. I have switched to 93 to try it out for couple tanks now that gas is cheap, and I dont feel the difference. I plan on switching back to 87


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## KarstGeo (Jan 19, 2018)

mdtony said:


> Good information, thank you. I have switched to 93 to try it out for couple tanks now that gas is cheap, and I dont feel the difference. I plan on switching back to 87


I note the same - no discernable difference to me to justify the additional cost for just driving around town.


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## kazimir80 (Mar 15, 2019)

It depends on what are you expecting from VR6 and how long you plan to keep the car. This engine was designed for 98 octane RON which is available in EU. No other petrol than 95/98 is offered there. Maybe some sort of for saw mowers petrols and such. 

The problem is not about the "power" it is about carbon build up. Less octane is proven to carbon more than higher octane with aditives. There are plenty of articles about it among European owners that 95 RON octane is much worse than 98 RON and than tne engine is rapidly losing its power as it is dirty inside.

I am using premium to help preventing it.


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## KarstGeo (Jan 19, 2018)

kazimir80 said:


> It depends on what are you expecting from VR6 and how long you plan to keep the car. This engine was designed for 98 octane RON which is available in EU. No other petrol than 95/98 is offered there. Maybe some sort of for saw mowers petrols and such.
> 
> The problem is not about the "power" it is about carbon build up. Less octane is proven to carbon more than higher octane with aditives. There are plenty of articles about it among European owners that 95 RON octane is much worse than 98 RON and than tne engine is rapidly losing its power as it is dirty inside.
> 
> I am using premium to help preventing it.


I don't buy that for a minute - plenty of articles/info saying the opposite - the fuel simply has zero to do with carbon build up on the back of the valves that it doesn't touch anyway. DI motors will simply build carbon on the intake valves and walnut blasting is just an inevitable reality now. In Euro, many VWs come with additional MPI to help. Oil type (NOAK) also doesn't help or catch cans. Here, "Top Tier" fuels whether 87/89/91/93 will all have the same detergent/additive pack to help with the fuel injectors. 98 RON = 93AKI/(R+M)/2 here in the U.S and 95 ROM = our 87.


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## kazimir80 (Mar 15, 2019)

Yes, all DI petrol engines have problem with carbon buildup. Depends on what you tank and how much the fuel is making it. It depends on fuel, additivies, detergents and such (by legislative). 98 RON should not have any ethanol and bio additives added.

I believe 91 MON = 95 RON
In the United States, octane ratings in unleaded fuels vary between 85[68] and 87 AKI (91–92 RON) for regular, 89–90 AKI (94–95 RON) for mid-grade (equivalent to European regular), up to 90–94 AKI (95–99 RON) for premium (European premium). 
source https://en.wikipedia.org/wiki/Gasoline

European Union
In the EU, 5% ethanol can be added within the common gasoline spec (EN 228). Discussions are ongoing to allow 10% blending of ethanol (available in Finnish, French and German gas stations). In Finland, most gasoline stations sell 95E10, which is 10% ethanol, and 98E5, which is 5% ethanol. Most gasoline sold in Sweden has 5–15% ethanol added. Three different ethanol blends are sold in the Netherlands—E5, E10 and hE15. The last of these differs from standard ethanol–gasoline blends in that it consists of 15% hydrous ethanol (i.e., the ethanol–water azeotrope) instead of the anhydrous ethanol traditionally used for blending with gasoline. 

souce few paragraphs under https://en.wikipedia.org/wiki/Gasoline


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## jrhelbert (Mar 18, 2019)

KarstGeo said:


> I don't buy that for a minute - plenty of articles/info saying the opposite - the fuel simply has zero to do with carbon build up on the back of the valves that it doesn't touch anyway. DI motors will simply build carbon on the intake valves and walnut blasting is just an inevitable reality now. In Euro, many VWs come with additional MPI to help. Oil type (NOAK) also doesn't help or catch cans. Here, "Top Tier" fuels whether 87/89/91/93 will all have the same detergent/additive pack to help with the fuel injectors. 98 RON = 93AKI/(R+M)/2 here in the U.S and 95 ROM = our 87.


I agree with the first part, in a DI engine the fuel will never touch the intake valves and no additives or detergents will change that. The carbon build up is from the the PCV system, all the exhaust gases and oil vapors land there and without port injected fuel it will never get cleaned off.

I disagree with the statement that catch cans don't help. They wont be perfect, and there will still be some build up, but it will be considerably reduced since a catch can (at least a good and properly sized one) will precipitate and filter most of that junk out.


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## Andre VW (Dec 12, 2018)

Good initial data for full throttle. Since the VW programming is actually for 87 there isnt much to gain with a stock tune. Where you can “maybe” gain with the stock tune is in the partial throttle range. What may be interesting to look at also is partial throttle in particular at peak torque rpm ranges in the lower part of the rev band.

The lower RPM band and partial throttle is really where ignition advance is king and might see larger gains with 93 vs 87. This will give you responsive throttle response and higher torque which will give the engine a more peppy feel. Again this is all stock tune so one shouldnt expect to gain anything other than the 93 will ensure nothing is left on the table. Engine knock in particular is problematic at the partial throttle and this is where the ECU will likely retard ignition with 87 to prevent knock. The 93 will help minimize any retard for the around town driving.

$ for $ unlikely to gain much with the stock 87 tune on an Atlas running 93. If one can find the porsche cayenne tune for 91+ for this same exact VR6 engine, thats where you will see lots of engine responsiveness and low partial throttle torque with the Porsche tune on this engine. 


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## KarstGeo (Jan 19, 2018)

Andre VW said:


> Good initial data for full throttle. Since the VW programming is actually for 87 there isnt much to gain with a stock tune. Where you can “maybe” gain with the stock tune is in the partial throttle range. What may be interesting to look at also is partial throttle in particular at peak torque rpm ranges in the lower part of the rev band.
> 
> The lower RPM band and partial throttle is really where ignition advance is king and might see larger gains with 93 vs 87. This will give you responsive throttle response and higher torque which will give the engine a more peppy feel. Again this is all stock tune so one shouldnt expect to gain anything other than the 93 will ensure nothing is left on the table. Engine knock in particular is problematic at the partial throttle and this is where the ECU will likely retard ignition with 87 to prevent knock. The 93 will help minimize any retard for the around town driving.
> 
> ...


Certainly can be the case - was just an easy way to have some control over the conditions by doing WOT pulls and that is typically where I see some timing pull. The logs show it clearly that you get less on 93 which should equate to *some* extra power. I agree though, some around town logs with both 87/93 will also show some variance between them. I appreciate your comment "93 will ensure nothing is left on the table" - a great way to sum this up. Folks seem to think that running 93 unlocks a magical ECU map where you get a lot more power and it just isn't the case. It's like an intercooler on a turbo car, it doesn't add power it just reduces how much you lose.


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## flyboy1100 (Feb 15, 2009)

In my experience so far the engine handles the factory ultra low rpm and below the natural power band crap shifting schedule better while running 91 over 87. Less bogging and crappy sounds......otherwise we would just run 87

Im going to continue to run premium and if i could get a retune closer to warranty expiration for 91/93 i will. 


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## Andre VW (Dec 12, 2018)

flyboy1100 said:


> In my experience so far the engine handles the factory ultra low rpm and below the natural power band crap shifting schedule better while running 91 over 87. Less bogging and crappy sounds......otherwise we would just run 87
> 
> Im going to continue to run premium and if i could get a retune closer to warranty expiration for 91/93 i will.
> 
> ...


Your butt dyno is likely correct. The 91 will ensure miminal ignition retard and the ECU will detect less pre-ignition and therefore maintain ignition. If you are in a hotter climate, the 91 vs 87will help even more to maintain around town low rpm performance. 


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