Long Tube Headers & Check Engine Lights Explained

[gremlinsteve]

until a tuner who has been into and knows what the factory is commanding at wot as far in the ve and pe tables we wont know. i do not have access to the software any longer so im in the blind.
i cant see them commanding or at least needing to command a lot of timing. at 11 to one stock with the vvt i would assume that cranking pressure is pretty much high. to build low end torque.

hell most other makes only need about 24-26 degrees tops. thats at wot and usually all in pretty fast. the modern cyl heads are pretty efficient in that they do not need alot of wot timing.

in the past at my shop the several hundred cars we put on the rollers had no change or not enough change in hp and trq to justify the use of straight 100-103 octane fuels. now that changed when the tuner started to add timing and changed the pe and ve tables. allowing the motor to take advantage of the fuel.

as far as a gain in fuel mpg? i would say a straight tank of 100 would prolly do that. in fact a tank full of 93 octane would also do it if it did not have the e10-e15 blend. but i think that type of fuel is a dying breed.

 

[PeteInCT]

Steve, I agree. I only put 93 in her given that I'm always concerned that 91 gas may be a little 'weak'. Also, in my area the 93 octane fuels are Sunoco, Exxon/Mobil, etc. The 91's tend to be the off brands...

 

[gremlinsteve]

and i found that using shell has effects on a motor also. in my testing that we did we found that shell caused sometimes up to 6 degrees of knock retard in cars we ran.

when we switched to the exxon/mobile/chevron fuels we saw that the knock retard would go away and the car would pick back up.

we tested this theory of ours alot and i have come to the conclusion....if you have to use shell fuels, dont go racing....


steve

 

[PeteInCT]

Must be all that Nitrogen in their gas ;D What's funny is that Shell is by far the most expensive gas in my area also.

 

[CaliMR]

i personally think its a waste of time money and effort to run the 100-110 octane fuels. as you have stated.
the tune is only going to see xxx amount of timing. once it reaches that threshhold its a mute point.

could you spike a load of fuel with a few gallons of the 100? sure. i think thats a better choice. making up a 95 or so octane.
the higher the octane the faster the burn. hence adding timing to make the power.

and im still thinking that the vibrate performance GENIS style cat will help get rid of that pesky cel code for cat in-efficiency...
if it can be placed close enough to the head to get the temp up fast enough to satisfy the computer.

steve

Doesn't high octane burn slower?


I have always liked to splash a little 100 in at the track just to bump it a tad because CA gas is junk 91 (worse than normal 91) just for a slight safety margin. I don't care if the 1 or 2 octane bump gives me 3.5 more hp on the stock tune or whatever, I just don't want it knocking. But I am also used to tracking turbo cars where it is probably a little more important.


As far as street gas, I have only put Chevron in my car and all but 2 fill ups have been at the same station. I don't get any noticeable knock on TK. My turbo car had datalogging and I played with the mapping a bit, and I did notice differences in gas.

 

[gremlinsteve]

i know the people who own vibrant. i might get ahold of them and see if i can get some info on that new cat.

i gots a feeling its the placement of the cat in the system that causing the issue though. the other makes have that same issue also.


steve

 

[gremlinsteve]

yes
i had a moment of dyslexia. sorry

 

[nota4re]

i wonder if a set of the vibrate performance GENIS style converters will also help remedy the issue with the cel. seems its worth a shot.

I can assure you that a single GESi CAT will not work. These are probably the best cats on the market and the make a lot of OEM stuff. If you want to "fix" the light on a Boss with LT's, you take 2 GESi per side and siamese them together. Now, go look at the cost to add 4 of these CATs to a system and you will know why I said in my original post that there is a solution - but it is cost prohibitive.

 

[gremlinsteve]

thats interesting to know. my contact says that these should work. there a brand new cat they are making. maybe 6 months on the market or so...

 

[lbp]

i personally think its a waste of time money and effort to run the 100-110 octane fuels. as you have stated.
the tune is only going to see xxx amount of timing. once it reaches that threshhold its a mute point.

could you spike a load of fuel with a few gallons of the 100? sure. i think thats a better choice. making up a 95 or so octane.
the higher the octane the faster the burn. hence adding timing to make the power.

and im still thinking that the vibrate performance GENIS style cat will help get rid of that pesky cel code for cat in-efficiency...
if it can be placed close enough to the head to get the temp up fast enough to satisfy the computer.

steve

Doesn't high octane burn slower?


...burns in a more controlled/consistent fashion (without pre-ignition).


I have always liked to splash a little 100 in at the track just to bump it a tad because CA gas is junk 91 (worse than normal 91) just for a slight safety margin. I don't care if the 1 or 2 octane bump gives me 3.5 more hp on the stock tune or whatever, I just don't want it knocking. But I am also used to tracking turbo cars where it is probably a little more important.


As far as street gas, I have only put Chevron in my car and all but 2 fill ups have been at the same station. I don't get any noticeable knock on TK. My turbo car had datalogging and I played with the mapping a bit, and I did notice differences in gas.

 

[gremlinsteve]

exactly.

im in houston. im sure we have the same fuels they have in cali these days. ours does say 93 though. but i dont trust the epa nazis these days.

 

[CaliMR]

I know the canned tune guys often have a separate tune for 93, 91, and CA/AZ/NV 91 because it is basically gasoline flavored pee. It is pretty noticeable running a turbo motor.

 

[gremlinsteve]

We get the oxygenated fuels. But yall must get some
Moose piss. You would think one standard fuel
For the country would be a cheaper prospect

Guess when the goverment gets involved with anything
Common sense goes out the window

 

[nota4re]

thats interesting to know. my contact says that these should work. there a brand new cat they are making. maybe 6 months on the market or so...

Key word here is "should". We thought so too. They don't. We are using these latest CATs and the folks at GESi have been very good with us.

To your point about placement - yes and no. For best cat warm-up times, the OEMs are placing the cats as close as possible to the heads. In the Mustang (and most other cars), the CATs are no longer under the car, the are in the down pipe IMMEDIATELY after the manifold. In a long tube header set-up, we have the placed immediately after the collector. However the collector is damn near under the car because of the tubing length.

To conclude this thread....

No CEL is possible on an OEM-tuned cars by having two cats in series per side - 4 cats total. Alternatively, you can run a tune which supresses the CEL for the cat efficiency faults. Those are the two options.

 

[lbp]

thats interesting to know. my contact says that these should work. there a brand new cat they are making. maybe 6 months on the market or so...

Key word here is "should". We thought so too. They don't. We are using these latest CATs and the folks at GESi have been very good with us.

To your point about placement - yes and no. For best cat warm-up times, the OEMs are placing the cats as close as possible to the heads. In the Mustang (and most other cars), the CATs are no longer under the car, the are in the down pipe IMMEDIATELY after the manifold. In a long tube header set-up, we have the placed immediately after the collector. However the collector is damn near under the car because of the tubing length.

To conclude this thread....

No CEL is possible on an OEM-tuned cars by having two cats in series per side - 4 cats total. Alternatively, you can run a tune which supresses the CEL for the cat efficiency faults. Those are the two options.

Any possibility of grafting the OEM CAT onto the aftermarket downtube?
I suppose the reason not would be too restrictive.
Could cutting further up onto the oem cat housing (before reaching the cel material) at least get the diameters correctly matched?
Anyone tried this?

 

[nota4re]

The diameter of the OEM cas is too big for consideration with LT headers. As I said, the cats are no longer vertical after the LT's are on and therefore diameter is going to play a key role to restrict the size.

 

[Justin]

in a hp tv episode where they put the coyote engine on there dyno....it had ford racing long tube headers. I have there new catalog and there not in there anywhere. anyone know if they are coming out or are already out? and if it will have a mid pipe with cats that will work and work with boss side exhaust?

 

[gremlinsteve]

i highly doubt it.
cat placement is one of the big issues. how fast that cat comes up in temp is measured. all the cars out there do it now. is the obd2 stuff. some can get away with the oil spark plug anti fouler trick. most cant. and these cars have the wideband. to boot.

 

[CaliMR]

Does anyone make a cat heater? Maybe clamp a glow plug to it

 

[gremlinsteve]

Then u have a rear o2 sample issue