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Discussion Starter · #1 ·
I am planning on installing a set of JBA silver coated 1.75 long tube on my car. I am wondering If I will need a tune for my 2010 Dodge Charger SRT8 with the 6.1 Hemi. The car currently has a K&N CAI kit installed on the car with Borla ATAK cat back exhaust. It is running the 91 Octane CAI tune at the present time with a diablo sport intune i1000 tuner.

Would it be best to acquire a complete new tune, or adjust existing tune fuel maps with the i1000 tuner?

Where would be the best place to acquire a tune to accommodate the headers?
 

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There is absolutely no requirement for a tune after installing properly designed long tube headers. The gains are as a direct result of their design (Helmholtz Effect).

Any "extra" gain a tune might offer would not be from the headers but from dipping into available gains (minor) from altering timing and A / F.

So try not to buy into the rhetoric that tries to claim otherwise (especially if there is a vested interest :^).
 
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Discussion Starter · #4 ·
Been doing some reading as well and it seems that the majority of guys opt for the 1 7/8 headers over the 1 3/4 headers. There seems to be some great debate in regards to bigger being better or vice versa if you are looking for torque/hp and in what RPM range.
 

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Swapping long tube headers into say a 5.7 does improve scavenging and change WOT AFR. WOT power enrichment is not controlled by the PCM via O2 sensor feedback but instead by a table that gives FA adders based on aircharge and RPM that are optimized for the 5.7 log type manifolds. Back in the day when you swapped in headers on a carb''ed engine folks would usually increase jet size to correct for the increase airflow headers provided. If you are installing headers, add an extra O2 bung at the collector so you can see for yourself whether your AFRs are good at WOT.

Oh and there is also an O2 transport delay that most tweak in the tune as the upstream O2 sensor position is now much further away from the exhaust ports. And finally if you don't want the mil light to show up for cat inefficiency you might want to turn those DTCs off in the tune, increase the COT temp so PCM does not think cats get hot and start dumping fuel and maybe bump up the downstream O2 closed loop temp so they are ignored by the PCM. You won't pass any emissions tests doing so though.
 

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Discussion Starter · #6 ·
Swapping long tube headers into say a 5.7 does improve scavenging and change WOT AFR. WOT power enrichment is not controlled by the PCM via O2 sensor feedback but instead by a table that gives FA adders based on aircharge and RPM that are optimized for the 5.7 log type manifolds. Back in the day when you swapped in headers on a carb''ed engine folks would usually increase jet size to correct for the increase airflow headers provided. If you are installing headers, add an extra O2 bung at the collector so you can see for yourself whether your AFRs are good at WOT.

Oh and there is also an O2 transport delay that most tweak in the tune as the upstream O2 sensor position is now much further away from the exhaust ports. And finally if you don't want the mil light to show up for cat inefficiency you might want to turn those DTCs off in the tune, increase the COT temp so PCM does not think cats get hot and start dumping fuel and maybe bump up the downstream O2 closed loop temp so they are ignored by the PCM. You won't pass any emissions tests doing so though.
Wow. Theres a mouthful and I'd be lying if I said I wasn't concerned by a number of things in this endeavor. These 1.75" JBA ceramic coated longtubes would be be going onto a 6.1 hemi....not a 5.7. Most of which suggest 1.875 Longtubes for the 6.1 or 6.4 hemi...although there is a fair amount of guys who suggest the smaller primaries of the 1.75 longtubes fair better to the torque side and lower, most used RPM band....the cats will most likely be removed and replaced with offroad midpipe (catless)...this will already cause me some issue with CEL and NOISE. There is no room to use the existing cats and I have concerns about ground clearance. The Borla atak system is very civilized in the lower RPM range until 4000 RPM then it is VIOLENT. With longtubes and catless midpipes I'm certain it will be unbearable and garner some bad attention from the wrong people (the po po).

I will need a tune with the headers and mid pipes regardless of which size is chosen.....i'm just starting to wonder if the benefits of the longtubes is going to exceed the efforts. By the time its all said and done....I'm looking at $1300-$1400 for headers and midpipes, another $600-$700 for the install....and another $300-$400 for tune. I'm starting to think that at $2400ish.....this may not be worth it?
 

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Yup you gotta pay to play with these modern hemis. Fortunately you don't need to spend $250 to get the PCM unlocked. Don't think you will see big gains with LT headers...not as much as a 5.7 but it will sound killer under WOT. Main thing is to make sure you use OEM gaskets and get new exhaust studs/bolts if you do decide to go thru with it.
 

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Unless my exhaust guy sharpens his pencil, I"m thinking this may be a bust. Money may be better spent on cam (Inertia srt max plus or srt torque max) first before the headers.
The best path would be to do the cam and headers at the same time. It will be begging for headers once you add a good cam, and you can do more with the cam with a free flowing exhaust...
 

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Without a tune expect to pickup 10/15 HP. Your cars computer will react to the headers and make the appropriate adjustments to the AF. That said, a tune definitely will squeeze more. The computer will be adjusting for a 14.7 AF ratio. That's it! It is a fixed goal in the computer. A tuner can change the fixed goals.
 

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Without a tune expect to pickup 10/15 HP. Your cars computer will react to the headers and make the appropriate adjustments to the AF. That said, a tune definitely will squeeze more. The computer will be adjusting for a 14.7 AF ratio. That's it! It is a fixed goal in the computer. A tuner can change the fixed goals.
You still want 14.7:1 at idle/cruise. Its fueling at WOT and during transition that will generally need some dialing in with longtubes.
 
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