Gas Question

[J]

i have a 2005 h2 i had a XTREMEFLOW Muffler & Intake System and i was using 87 for gas could that be the problem it was not working good now i use the 91 but with the original parts. what gas do you all use

[J]

i have a 2005 h2 i had a XTREMEFLOW Muffler & Intake System and i was using 87 for gas could that be the problem it was not working good now i use the 91 but with the original parts. what gas do you all use

[KenP]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by J:
i have a 2005 h2 i had a XTREMEFLOW Muffler & Intake System and i was using 87 for gas could that be the problem it was not working good now i use the 91 but with the original parts. what gas do you all use </div></BLOCKQUOTE>You should not need 91 unless you have a "hot" setup with a programmer or a Super Charger.

[Fubar]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by J:
i have a 2005 h2 i had a XTREMEFLOW Muffler & Intake System and i was using 87 for gas could that be the problem it was not working good now i use the 91 but with the original parts. what gas do you all use </div></BLOCKQUOTE>

The owners manual suggests 87 so I wouldn't think that the grade of gas you are using is or was causing a problem with your muffler. Even after being supercharged I'm albe to run 87 without any problems.

[ROX]

Is your rig running better now? Maybe you had a bad intake or a damaged muffler. The type of gas you use should only affect the engine performance, and even with those mods it shouldn't matter. Sometimes running low octane in hot weather will make it ping more, but I haven't ever noticed it with this particular engine. Do you fuel at the same spot all the time? Sometimes your favorite station can get a tank of bad gas. (that's probably only here in Oregon, though, where they don't believe in testing their fuel )

I've been running a mid to hi octane and I've traveled all over the West. No problems with performance, unless you count the number of times I've needed a few more inches of throttle.

[KenP]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by H2 Rocks:
No problems with performance, unless you count the number of times I've needed a few more inches of throttle. </div></BLOCKQUOTE> Yeah, that calls for a response of some sort. I'm sure someone will come up with something.

[ROX]

You can never have too much of a good thing!

[KenP]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by PhilD:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by KenP:
You should not need 91 unless you have a "hot" setup with a programmer or a Super Charger. </div></BLOCKQUOTE>Ken, I have a question about this actually. What is programmer doing to get more power? I'm guessing it advances the timing and changes the air/fuel ratio, but not really sure.

I've used mine on 91 Octane Performance running 87 gas and didn't have pre-ignition even under hard acceleration. I still run the 87 Octane Performance program though as it does the job just fine for me. </div></BLOCKQUOTE>Timing, air/fuel and shift points are the main ones. Sometimes people won't get pre-ignition until the upper RPM range of each gear. Or a pinging at the shift. It sounds as if most programmers just give you choices. When I say "hot setup" I mean actually going into the programming and tweaking each point individually. I don't know if you can do that with "everyday" programmers. I think this is what Taz is looking into with the Nelson.

[PARAGON]

You can advance/retard timing...... uhmmmm and other stuff ..... with the Predator. It's been so long since I did mine I can't remember what all changes I made.

[HUMMERcustoms.com/TAZ]

Ken
You, PARAGON, and Phil have hit the nail on the head with the tuning and octane of fuel used.
The over the counter programers leave so much HP and torque on the table You could gain easily 50 HP or torque with wideband tuning and really more. The superchips programmer that comes with Radix SC leaves about 40 HP on the table as a cushion, so Magnuson does not want the average guy who is a good mechanic and that will do the install himself to get full benefit of SC so that in case He puts 87 in instead of 91 or 93 He is not going to do damage until He can add octane booster to cover mistake or just burn till ready to go back in tank with 91. Yet handhelds work because the factory also leaves even a greater amount on the table. I have been researching wideband and talking to Allen Nelson and HP Tuning and what the wideband does is as Ken explained. You can with a very well written program go and get all the HP etc. left by other tuner programs safely because You are getting more acurate numbers in detail. You decide how much power You leave for a cushion. The handhelds are conservative because they do not want anyone going out and blowing up an engine and getting blamed for it. Allen can do a PCM upgrade that will get some of HP on the table left by handhelds but, He as a good business man does not get overly aggresive just as anyone else who would wideband tune Your rig hold back for safety and liability. Yet Allen does push the outer limits more than others to get more. He knows what he is doing and has already set limits that He will not go beyond because He is not there everyday to watch and see what you are doing right or wrong. To really do it right You have to go deep into the PCM and tune each little point that handhelds just tune in general. Ken You gave as good an explination as could be given about the tuning. Allen recommends HP Tuning and said it is so good most anyone can take it with a learning curve in consideration, study up on it and learn to program better than handhelds. He said the more You use it the better you get it.
HP Tuning will soon have their software with a 3 bar density ability that will remove MAF from the intake system completely. I mean figuratively as well as physically take it off and not use it. But, it requires time to learn it and safely do that and get all that the engine and ignition will deliver. Honestly unless You are racing or just like to play with this stuff most do not need to tune to such detail. I feel that most just do not need more than a handheld will do. Wideband is really for a person to just be able to know and learn more about what the setup is doing with forced induction. You could take wideband and add nothing to Your engine setup and tune it to run better with all stock setup. This is what the handheld is doing, you would just be more aggresive with wideband. You would just be limited to how much you can do by having stock engine components. If You shop around the handheld can be gotten for as little as $325 where as the software will run $1000 plus depending on the add ons You put with it.

Phil on the octane and programers You are on the money. I have mentioned it several times but, You reinterated My points made before about handhelds and octane. I have been running handhelds on 87 octane on both My Silverado since 1999 and Mall Queen since last 10/04 but with programmer set at the most high performance setting. There are 2 reasons a person can get away with this which You and Ken covered. The programmers are not overly aggresive and more importantly the octane You see posted on the pump is a minimum rating it can be at any given time that an inspector from the state comes by and does a test to see if retailers are within the guide lines. I have a friend who is a Chemical engineer with a big oil company and He said 87 could be any number above that as when gas sets it loses it's rating value or ability to prevent detonation. He said because of the time it is produced and delivered it usually starts out higher. The lower the octane the more volatile it is and the lower the octane is, the greater power it in theory will generate. This is contrary to what most think octane is about. Higher octane in itself will not give you more power. It just let's You advance timing and gain HP that way without detonation. But, the lower the octane is the more unstable it is. This idea is what causes it to detonate just by the pressure put on the air/fuel mix in chamber as piston comes up to top, compress and igniting it before you even add spark. The lower the octane You can run and not get detonation the more power You can get from that explosion along with advancing the timing. A very tricky little dance or game to play is finding that limit and every engine can be different. The higher the octane the harder it is for it to ignite and thus You can advance timing for more power. But, again the more You can advance the timing and run lower octane the more power you will have but, if You do not do it gradually with software you can jump past that point of safety and BOOM. New engine.
Well guys you did a very good job explaining it all and all I can do here is back up what you have already explained with the indepth discussions I have had concerning this stuff.
Good info by You all.
TAZ

[KenP]

Thanks Taz. BTW, check your mail.

[ROX]

Good explanation TAZ! Thanks!

[tower]

Well, since there is such a wealth of knowledge on octane here, could you please tell me if this is fact or myth?

I have heard from many mechanics that it is good practice to put a full tank of Hi-Test in my tank once every 6 to 10 fill-ups for purpaces of minimizing build-up inside the engines. What say you all? Fact or myth? Thank you!

[HUMMERcustoms.com/TAZ]

Tower most gasolines come with detergent in them and are going to keep engine as clean as gas can. Higher grade will not neccesarily do any better job cleaning it has same detergent as low grade. Build up etc. is due primarily to rich air/fuel mix. Get a good injector cleaner additive and run it every 2 or 3 tanks. If you suspect a problem go to dealer or any reputable mechanic with the equipment and they have a machine they can hook up and flush combustion chamber to clear carbon. They use machine along with an additive that they flush through it. Stuff in tank helps get rid of impurities left in fuel lines.
I feel it is a myth to run high grade. besides I do not think one tank full would do that much good even if it did help.
Hummer techs can probably help more with this issue.
TAZ

[Fubar]

just my two cents worth.
Personally I'd check with a mechanic you trust before using an over the counter injector cleaner. Over the counter injector cleaners have been know to cause injector damage. If you have a mechanic you trust I'd recommend having them clean your injectors or at least pull them and inspect them.
I agree that the higher octane fuels do not have any more detergent in them then the lower octane and one tank ever now and then is not going to help reduce build up.