OK...lets talk about high octane fuels and your car

[HOXXOH]

LPM ran FNBADAZ06 on the dyno today, complete with wideband O2 monitoring and HP Tuners data logging

3 runs with standard Shell 91 pump gas.

3 runs with approximately 50/50 mix of Sunoco GT+ (R+M/2 = 104) and Shell 91 octane pump gas (R+M/2 = 91).

I want to look over the logs before I post all the information, but on the surface, my suspicion was confirmed....I'm getting the boost I felt I was getting

So what do you call that mix? Sunhell or Sheloco?

[FNBADAZ06]

The FNBADAZ06 mix......and the results posted in my dyno thread appear to backup my idea that I'm getting the boost I felt I was getting.

OK...so now we can debate.

Did the 50/50 mix help my stock tuned LS7, and if so, where did the power increase come from ?

On straight pump gas , my average of the two good non-heat soaked runs is 475.34 RWHP, 446.78 Tq.

On my 50/50 mix, using all three runs to include the higher ECT beginnings and heat soaked passes to bias the number down.......

481.51 average RWHP

454.24 average RWTQ

...gives me gains of

6.17 RWHP gain

7.46 RWTQ gain

Use the average for the two best runs pushes the RWHP gains up just a bit...

482.59 average = 7.5 RWHP gain

454.58 average = 7.8 RWTQ gain

No KR on any of the 50/50 mix , which ends up to be roughly 97.5 octane.

The 91 pump runs had the advantage of superior ECT's to begin and finsih the runs, but had some KR near the upper RPM.

The 97.5 octane oxygenated fuel mix all begin their pulls in excess of 196* , with the two final pulls getting near and above the factory tune ECT barrier where timing is pulled, running LESS overall total timing....and they still made more power than the 91 run's....interesting.

[Buccaneer]

AWESOME info Vic!

[Two Fangs]

Well, looking at just a screen capture, it certainly appears that there is a higher MAP signal on the race fuel mix when compared to straight 91. I am certain that this is where the gains are coming from. Higher manifold pressure equates to more air being forced into the cylinder. This can be caused by either an increase in volumetric efficiency, or an increase in barometric pressure. If the barometer stayed the same between the two tests, I would have to say that the engine was able to perform better with the race gas mix, most likely due to a more optimized cylinder pressure, since any change in A/F appears negligible between the two fuel types. Of course, I strongly encourage folks to post a counter argument .

[FNBADAZ06]

Well, looking at just a screen capture, it certainly appears that there is a higher MAP signal on the race fuel mix when compared to straight 91. I am certain that this is where the gains are coming from.

Higher manifold pressure equates to more air being forced into the cylinder.

This can be caused by either an increase in volumetric efficiency, or an increase in barometric pressure.

If the barometer stayed the same between the two tests, I would have to say that the engine was able to perform better with the race gas mix, most likely due to a more optimized cylinder pressure, since any change in A/F appears negligible between the two fuel types.

Of course, I strongly encourage folks to post a counter argument .

What I found interesting was the AFR's.....on average it looked like the 50/50 mix ran a bit more RICH at the beginning of the runs ???

When does the OEM tune go into open loop when you go WOT.......when the TPS reads 88.....or does it also take into account RPM and load ?

Could the richer 50/50 mix be giving me superior torque down low that carries to the higher rpm HP figures ?

SAE corection numbers for all runs.....same basic environmentals.

[Two Fangs]

According to the stock tune I have, it does not appear that Power Enrichment is even a factor at that low of an RPM, since the stock tune builds a delay into PE below 5,000 RPM. While the runs may start a bit richer, this may just be a slight fuel trim issue while the car tries to figure out the mix, there is nothing there that jumps out at me, anyway. I still believe the answer lies in the efficiency of the engine as evidenced by the MAP.

[FNBADAZ06]

Sent you the tuner log files

[Two Fangs]

Thanks for the run files, I will take a look at them this evening.

In the meantime, here is a small 2D table that shows what open percentage the throttle needs to be at versus RPM to enter PE.

[FNBADAZ06]

Thanks for the run files, I will take a look at them this evening.

In the meantime, here is a small 2D table that shows what open percentage the throttle needs to be at versus RPM to enter PE.

Cool......learning more every day

It will be interesting to see what you find. I re played the logged runs.....on the surface it looks like the MAP readings stay fairly consistent.....hhhmmmm

[Two Fangs]

For comparisons sake, watch run logs 2 and 4 all the way through. Log the highest number you see in each. Difference? Remember that MAP when measured in kPa makes it easy for us to determine VE. When we determine power production capability based on VE, and the witness the VE improve, HP will improve as well.

[FNBADAZ06]

For comparisons sake, watch run logs 2 and 4 all the way through. Log the highest number you see in each.

Difference?

Remember that MAP when measured in kPa makes it easy for us to determine VE. When we determine power production capability based on VE, and the witness the VE improve, HP will improve as well.

98 kPa max reading several times, as early as 2600 RPM range, on run 2 .....417.79 g/sec max reading as well at 6,659 RPM.

99 kPa max reading several times, as early as 2600 RPM range, on run 4.........429.95 g/sec max reading at 6,592 RPM.

[NicD]

The PE RPM delay in the car calibrations almost never gets referenced in the code, mostly only in truck/SUV calibrations does that even do anything. It should be in PE from the beginning of the dyno to the end and that rich tip in is probably just the transient fueling kicking hard depending on how fast the pedal was hit when going WOT. My guess if everything else is consistent between the timing and MAP readings that it's just the fuel mixture is a bit more efficient or has a bit more energy in it or is more/less oxygenated, etc. I skimmed it so far so tell me if I am wrong here but it sounds like the tests were done back to back? That should eliminate any small amount of air pressure change that would show up on a dyno chart or map readings so to speak.

[FNBADAZ06]

The PE RPM delay in the car calibrations almost never gets referenced in the code, mostly only in truck/SUV calibrations does that even do anything. It should be in PE from the beginning of the dyno to the end and that rich tip in is probably just the transient fueling kicking hard depending on how fast the pedal was hit when going WOT.

My guess if everything else is consistent between the timing and MAP readings that it's just the fuel mixture is a bit more efficient or has a bit more energy in it or is more/less oxygenated, etc. I skimmed it so far so tell me if I am wrong here but it sounds like the tests were done back to back? That should eliminate any small amount of air pressure change that would show up on a dyno chart or map readings so to speak.

Yep....all runs performed within 1.25 hours start to finish.

I had approximately 1 hour cool down between the first three runs on stadard pump gas...then three more runs on my mix. We ad a bit of trouble with the dyno going into the last three runs, so the ECT's were considerably higher for the last 2 runs....but I still made more power even with the ECT timing pull's that happen above 214* , IIRC The last pull began with ECT's above 220* , but still made 480+

I highlighted your comment above, as my contention is that the fuel, in addition to warding off KR, may be giving me additional HP (on my stock tune) as well due to the oxygenated nature of the fuel....here's the spec again for the Sunoco fuel I used in my mix :

Color Light Blue

Octane (R+M)/2 104

Research Octane 109

Motor Octane 99

Specific Gravity 0.759

Weight (lbs/gallon) 6.3

Reid Vapor Pressure 6.3

Initial Boiling Point 98

10% Evaporation 144

50% Evaporation 217

90% Evaporation 228

Final Boiling Point 245

Stoichiometric Air/Fuel Ratio 14

Oxygen (weight%) 4.8

Ethanol (volume%) 13

HC Ratio 1.92

OC Ratio 0.044

Lower Heating Value (Gallons) 110500

Lower Heating Value (lbs) 17500

Dielectric Constant 18

I sent M. Parker the log files to review later this evening so he can see everything

[NicD]

Also just looking at the run conditions on the dyno chart they are damn near identical so I wouldn't expect there to be that much of a difference between them airflow wise at all.

[Two Fangs]

The PE RPM delay in the car calibrations almost never gets referenced in the code, mostly only in truck/SUV calibrations does that even do anything. It should be in PE from the beginning of the dyno to the end

I have seen this in a lot of LS1s, and LS2s, but in E38 LS3s and LS7s, it seems like it takes a bit for the fuel trims to be ignored. Maybe it's just me.

***EDIT*** Not like it matters, because I change all of that stuff in a tune, anyway

[NicD]

The PE RPM delay in the car calibrations almost never gets referenced in the code, mostly only in truck/SUV calibrations does that even do anything. It should be in PE from the beginning of the dyno to the end

I have seen this in a lot of LS1s, and LS2s, but in E38 LS3s and LS7s, it seems like it takes a bit for the fuel trims to be ignored. Maybe it's just me.

***EDIT*** Not like it matters, because I change all of that stuff in a tune, anyway

I don't think I've ever seen it delay like that even on the E38s but I hear ya, that stuff gets changed in the tune anyways to keep it looking copacetic so it's been a long time since I've even looked at it that way.

[Two Fangs]

98 kPa max reading several times, as early as 2600 RPM range, on run 2 .....417.79 g/sec max reading as well at 6,659 RPM.

99 kPa max reading several times, as early as 2600 RPM range, on run 4.........429.95 g/sec max reading at 6,592 RPM.

The engine is certainly getting more air, and this is getting the power higher, but what is causing it?

Nic has a good point, the energy the fuel possesses is important.

Additionally, there is no real difference in the atmosphere. What we do know, based on the data we have, is a change in fuel caused it. My postulation is the engine is able to achieve a greater level of VE, by changing when the energy peak is being placed on top of the piston.

I see a lot of racers in every aspect of the sport checking the fuel for specific gravity and adjusting jetting and timing accordingly. If it were not important, why bother?

[FNBADAZ06]

98 kPa max reading several times, as early as 2600 RPM range, on run 2 .....417.79 g/sec max reading as well at 6,659 RPM.

99 kPa max reading several times, as early as 2600 RPM range, on run 4.........429.95 g/sec max reading at 6,592 RPM.

The engine is certainly getting more air, and this is getting the power higher, but what is causing it?

Nic has a good point, the energy the fuel possesses is important.

Additionally, there is no real difference in the atmosphere. What we do know, based on the data we have, is a change in fuel caused it. My postulation is the engine is able to achieve a greater level of VE, by changing when the energy peak is being placed on top of the piston.

I see a lot of racers in every aspect of the sport checking the fuel for specific gravity and adjusting jetting and timing accordingly. If it were not important, why bother?

: ...the cat is out of the bag

[Jon]

Makes me want to try this test on my bone stock except for Callaway Honker CAI LS3 and see what happens. Then we could have LS7 and LS3 test data.

[Two Fangs]

[FNBADAZ06]

Makes me want to try this test on my bone stock except for Callaway Honker CAI LS3 and see what happens. Then we could have LS7 and LS3 test data.

It would be very interesting to see this, Jon.

While I have a larger bore and higher compression than your LS3, it would be interesting to see how an LS3 would benefit, if at all, from my secret fuel mix

You noted before that you were getting burst knock at tip in for WOT operation...would my 97.5 (R+M/2) octane mix address this issue ?

Don't know.

[NicD]

Time to bust out the old school MAF translator to lean that sucker out further without delving into the PCM. That with the higher octane fuel and maybe a timing tricker would do some neat things while technically still being on the stock tune.

[Two Fangs]

MAF translator, haaa ha ha Going back to the old LS1 Edit and AutoTap days. That shit worked, though Crap man, we have it so easy this day and age.

[NicD]

MAF translator, haaa ha ha

Going back to the old LS1 Edit and AutoTap days. That shit worked, though

Crap man, we have it so easy this day and age.

LOL no doubt, back when a 224 cam was big and about all you could deal with before LS1edit was released. Hell I remember doing beta testing with Ken Kelly testing a cat overtemp switch before anybody knew what the hell was going on when the fueling would suddenly go rich. Nobody thought cat overtemp actually existed in the LS PCMs.

[Two Fangs]

Wow, interesting stuff re: Ken Kelly Yeah, everybody needed a "Top secret" B1 or T1 cam from MTI, or your shit was never going to go fast. I think they were HUGE in the 22x range I spent a lot of time in Houston with Little Elvis back in those days working on Vipers for Hen-shit and tuning Gallant's stuff. We worked getting that first Venom 1000 right, and then Dave Inall closed Incon and left John holding the bag for tens of thousands of dollars. We had five or six cars needing the kit and nary a one to be had.