How much boost are you all runnin' on 93 octane?

[bruce]

As air temp goes higher you need to advance the timing to regain the cylinder pressure lost do to the air being less dense.
So as the temp drops you then need to retard the timing.

As air gets cold the barometric pressure goes up.
Which means there is more exhaust back pressure. So you need to SLIGHTLY lean the fuel down as baro raises.

The stock MAF uses an entire table to compensate for IAT/MAT changes. For some reason they left the timing vs IAT/MAT table all 0'd out.

If all you have to tune with is adjusting the wastgate then that's your only cure.
Where as the proper cure is correcting the timing.

Removing screens, and such can also skew the MAF calibration to where you can get to no mans land.

 

[galoush]

15 -16 on 93 with 21deg of timming on the chip 25psi on c-16

 

[jojo]

Originally posted by bruce


Removing screens, and such can also skew the MAF calibration to where you can get to no mans land. [/B]

Hey Bruce i pulled one of the screens out from my maf, does that really make a difference? kinda funny with the post on 93 octane to. I just started running 91 octane, cause that is the highest pump gas out here in Vegas. I went from running nothing but 100 octane and about 23psi of boost no knock to running 91 octane having to drop the boost down to 16-17psi with 02s around 750 in 3rd gear. But as the cool weather flows through the intercooler i believe im definately getting better response. Any thoughts?

thanks

jojo

 

[strikeeagle]

Again, the average Joe who doesn't burn chips and uses the stock MAF has only boost and FP to play with.

BTW, porting your doghouse or putting 2 PSI less in your slicks may make you go quicker/faster, but it hardly "tuning".

Having owned 4 TRs over time, I can't see how anybody can run 20 PSI or anywhere near it on 91 to 94 octane in the summer, so let's just say I'm from Missouri...

 

[FLYNRYAN87]

With the smc alky kit and powerplate i run 21lbs on 91 pump gas. Without the alky and powerplate i can only run about 13lbs tops. ps with a red armstrong 107 chip. the truth is out now:

 

[jojo]

Originally posted by FLYNRYAN87
With the smc alky kit and powerplate i run 21lbs on 91 pump gas. Without the alky and powerplate i can only run about 13lbs tops. ps with a red armstrong 107 chip. the truth is out now:

**** im getting about 16psi on 91. You said your only getting 13?

 

[turbo buicks]

i knocked at 11 psi on 92 octane in midsummer down here in central florida. of course this was with bad injectors.

 

[jojo]

Originally posted by turbo buicks
i knocked at 11 psi on 92 octane in midsummer down here in central florida. of course this was with bad injectors.

Well i guess bad injectors would explain that, but 13psi on 91? actually i think my boost is set at 17psi right now on 91 octane. Maybe because of the cooler weather. 02s are at about 750 or so with 17psi.

 

[turbo buicks]

wow im glad we got 93 octane down here. i remember seeing 94 ocatne i think when i was little. my bad injectors would make audible knock @ 15 psi on a cold night.

 

[FLYNRYAN87]

13lbs of boost in the summer and about 16lbs in the winter. The air here in utah is very hot and dry in the summer.

 

[bruce]

Originally posted by jojo
Hey Bruce i pulled one of the screens out from my maf, does that really make a difference?

Any thoughts?

Yes, removing screens do adversly effect things.

You have enough of a hotrod, that you really need some tunibility to get it to run it's best, IMO.

When you run a chip all you can do is toggle the F/P and boost to try and dial it in.

To get to where you can do anything meaningful means going to chip burning, a ME, or translator Plus.

If you're thinking of really going quick you'll have to eventually get a Tranlator Plus, or MAFless ME.

 

[FLYNRYAN87]

Get an rjc powerplate and then see how far you can go on pump gas. My car was the original test car for the stock upper plenumand all i can say is i wish race jace would have thought of it along time ago.

 

[REDS HOT AIR]

last time i was in street trim on exxon 93 octane i was at 24# boost and 0 knock even when i raced my buddy's high 10 second monte carlo and he beat me by a car and he jumped me half a car at take off so he only pulled a half car on me

no alky

no power plate

and only 1 screen in the stock maf

20 degree timing chip

 

[Ormand]

Barometric Pressure?

Minor correction to Bruce's statement above. Barometric pressure and ambient temperature are independent. Barometer can go up as temp goes down, or it might go down as temp goes down. DENSITY and temperature are dependent. As temp goes down, with constant pressure, density increases. The pros at bracket racing use those little weather stations to measure temp, and barometric pressure, and humidity, so they can "set" their cars for the track conditions, and avoid breaking out.
Biggest contributor to cool weather performance is the cool air in, plus the cool air over the intercooler gives higher density. The MAF should account for this, though, and keep the mixture constant. (Since a MAF measures mass air flow, rather than volume) If the chip has proper timing tables, for MAF vs rmp, that should work out, too. Since the limit of the stock MAF is so low, most cars will go beyond that limit at WOT in cool weather, with moderate boost. (255 grams/sec= about 2020 lbs/hr, at 12:1 AF ratio, this corresponds to 28 lbs/hr for each of six injectors)

 

[bruce]

Re: Barometric Pressure?

Originally posted by Ormand
Minor correction to Bruce's statement above. Barometric pressure and ambient temperature are independent. Barometer can go up as temp goes down, or it might go down as temp goes down. DENSITY and temperature are dependent. As temp goes down, with constant pressure, density increases. The pros at bracket racing use those little weather stations to measure temp, and barometric pressure, and humidity, so they can "set" their cars for the track conditions, and avoid breaking out.
Biggest contributor to cool weather performance is the cool air in, plus the cool air over the intercooler gives higher density. The MAF should account for this, though, and keep the mixture constant. (Since a MAF measures mass air flow, rather than volume) If the chip has proper timing tables, for MAF vs rmp, that should work out, too. Since the limit of the stock MAF is so low, most cars will go beyond that limit at WOT in cool weather, with moderate boost. (255 grams/sec= about 2020 lbs/hr, at 12:1 AF ratio, this corresponds to 28 lbs/hr for each of six injectors)

You expanded on what I said, not corrected.

The ERROR in the GN setup is the IAT/MAT is in the wrong place, so what should be done isn't.

Once you change the airflow characteristics of the engine, you throw off the MAF calibration. Your 255 and related data is correct when using an oem air filter air filter housing, MAF piping, exhaust, etc etc.

While folks like to prdict out comes from gathering input info, wht placement of sensors is critical in gathering the right info..
To gather as accurate info as possible means gathering the info as close to the intake valve as possible. And that's a compromise since in chamber sampling is still some time away.

Now ask about going to ablow thru MAF, and relocating the IAT/MAT so that it's on the upper plenum.

Trouble is none of this is for weak of heart since it takes time and effort to get it all CORRECT.

This isn't aimed you, just an open response.
Tuning an tuning issues aren't one thread/letter answers.

 

[turbo buicks]

if you get a translator and LS1/LT1 MAF can it be mounted as a blow-through setup just as easily as a stock setup? or do you need the chip reprogrammed for a blow-through type setup?

 

[jojo]

Originally posted by REDS HOT AIR
last time i was in street trim on exxon 93 octane i was at 24# boost and 0 knock even when i raced my buddy's high 10 second monte carlo and he beat me by a car and he jumped me half a car at take off so he only pulled a half car on me

no alky

no power plate

and only 1 screen in the stock maf

20 degree timing chip

Wait a sec did i read this right? 24# on 93 pump? man that is awesome. How does one achieve such high boost on that octane?

thanks

jojo

 

[scottyb]

Originally posted by jojo
Wait a sec did i read this right? 24# on 93 pump? man that is awesome. How does one achieve such high boost on that octane?

thanks

jojo

Knock sensor was broke.

 

[jojo]

Originally posted by scottyb
Knock sensor was broke.

Are you sure your car didnt break?

 

[REDS HOT AIR]

Originally posted by jojo
How does one achieve such high boost on that octane?

thanks

jojo

if i really knew how i'd be a millionair by now.

all i know is its a killer combo and paying attention to all details not just tossing parts at it.

btw. i have single steel shim head gaskets also so my compression is higher than normal ..

seems to me letting the exaust out the motor seems to help alot

and biggest thing you can do to avoid knock is avoid any oil from contaminating the intake charge therefore you see i dont have any pcv valve putting oil in my intake...just a slight bit of oil will drop the octane of fuel down majorly.

putting suit on now for the attack by guys who dont agree with doing away with pcv valve
for those who say the oil gets contaminated from not having one my motor is spotless inside and besides I think its cheaper to change the oil than buy a bandaid like alky or propane.


ps knock sensor works fine ..

dont try this at home...results most likely will vary