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  #13  
Old 11-23-2009, 01:45 PM
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Re: Gains/Losses w/SRT exhaust on WK 3.7?

good info ryan!
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  #14  
Old 11-23-2009, 03:41 PM
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Re: Gains/Losses w/SRT exhaust on WK 3.7?

LOL...you are fine bro. Absolutely no need for the true duals unless you have major power adders going on the 3.7 in the future
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  #15  
Old 11-23-2009, 04:57 PM
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Re: Gains/Losses w/SRT exhaust on WK 3.7?

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Originally Posted by Scottina06 View Post
LOL...you are fine bro. Absolutely no need for the true duals unless you have major power adders going on the 3.7 in the future
The point is that it's far more ideal to run a true dual setup. Theres alot of surface area for the exhaust gases to cover without a merge to help scavenging (expelling gases out faster) . running a exhaust setup that optimizes scavenging has similiar effects to adding displacement.
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  #16  
Old 11-23-2009, 05:05 PM
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Re: Gains/Losses w/SRT exhaust on WK 3.7?

this is true...but on a truck that as he has said "I plan no more perfromance mods for" I was just saying its not really worth it unless he plans heavy perfomance mods. maybe he has changed his mind?
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  #17  
Old 11-24-2009, 03:29 AM
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Re: Gains/Losses w/SRT exhaust on WK 3.7?

Less backpressure is better,yes,but it can cause some other problems at low rpm. Rough idle for one and some vehicle computers have a problem with transition throttle response,going lean during quick throttle adjustments. Sounds alot like what TimmyB is experiencing. Not dangerous but annoying.

Max power is definately acheived with minimum backpressure but it's the part throttle driveability that suffers.
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  #18  
Old 11-24-2009, 01:58 PM
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Re: Gains/Losses w/SRT exhaust on WK 3.7?

I dont plan on doing any more engine mods to my little 3.7. But looking at it i dont see it being hard or expensive to cut off the stock Y pipe after the cats and have two straight pipes welded on back to the srt dual pipes at the axle. I took a picture of the exhaust layout page from my WK manual on disk, for some reason it wont let me cut and past the diagram.



Right now I have a single straight pipe on where the muffler should be. Right after where the muffler is shown in the pic is where my dual srt pipes start and i have a Y pipe there.



Here's my idea, install two pipes I drew in red in place of the single pipe i have on there now going to the dual srt pipes in there now shown in blue.

Right now I just think its odd how I have almost a "true dual exhaust" except for the Y and single pipe where the muffler goes. Im trying to research and understand if it will be beneficial to do what im thinking. Or would it make no difference.
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Old 11-24-2009, 02:03 PM
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Re: Gains/Losses w/SRT exhaust on WK 3.7?

Quote:
Originally Posted by Scottina06 View Post
this is true...but on a truck that as he has said "I plan no more perfromance mods for" I was just saying its not really worth it unless he plans heavy perfomance mods. maybe he has changed his mind?

Nope, you are correct. Im all about visual mods, and only did the srt set-up for the dual tips out the middle of the bumper. But since its on right now i'd be willing to go the extra step and add two pipes in place of the single pipe if it will be "better" for the motor and it might add a little HP.

Would a PCM flash help, though I really dont know what that is or does but I heard its a mod people do. Lol.
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Old 11-25-2009, 01:25 AM
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Re: Gains/Losses w/SRT exhaust on WK 3.7?

IMHO, it wouldn't make a sniff of difference. May however, change the exhaust note. True duals on a v-6 could be interesting to hear.....
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Old 11-25-2009, 01:37 AM
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Re: Gains/Losses w/SRT exhaust on WK 3.7?

Quote:
Originally Posted by 05wkguy View Post
Less backpressure is better,yes,but it can cause some other problems at low rpm. Rough idle for one and some vehicle computers have a problem with transition throttle response,going lean during quick throttle adjustments. Sounds alot like what TimmyB is experiencing. Not dangerous but annoying.

Max power is definately acheived with minimum backpressure but it's the part throttle driveability that suffers.
Not arguing but I have NEVER seen an issue with idle quality at low rpm relating to backpressure. The part throttle transition is a bit more plausible. I am not of the belief, however, that these are the problems Timmy here is seeing.

Before I started learning/studying EFI and the JTEC/NGC PCM through my own tuning and also in porting TBs for others, I was very into carb tuning for atvs/dirtbikes, motorcycles etc. A change in vacuum/backpressure would affect both areas that you describe, but it was because the carb was no longer jetted properly.

I am tempted to say that the above scenario sounds like a MAF-based system issue? Not MAP like the Jeeps.

From what I have seen the NGC PCM's do not as much of a capacity to adapt. They appear to be more fixed in their WOT fuel tables (i.e. you add a modification, the PCM will often not adapt much if at all to the newfound airflow, meaning a leaner WOT AFR) . The JTEC/JTEC+ seems to behave much differently in that regard.
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  #22  
Old 11-25-2009, 04:03 PM
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Re: Gains/Losses w/SRT exhaust on WK 3.7?

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Originally Posted by 05wkguy View Post
IMHO, it wouldn't make a sniff of difference. May however, change the exhaust note. True duals on a v-6 could be interesting to hear.....

To be honest I would like to hear what it sounds like back there, im always driving it so never had a chance to have someone else take it for a spin and hear it. I added alot of soundproofing to my doors, cargo floor, and cargo door so its pretty quiet in the cabin.

Thats all I was looking for:

A- Am I ruining my motor having the srt set-up on?

B- Would I benifit from making it a full dual exhaust like I drew in the pic?
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  #23  
Old 11-25-2009, 04:11 PM
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Re: Gains/Losses w/SRT exhaust on WK 3.7?

Quote:
Originally Posted by Sleepy4.7 View Post
Not arguing but I have NEVER seen an issue with idle quality at low rpm relating to backpressure. The part throttle transition is a bit more plausible. I am not of the belief, however, that these are the problems Timmy here is seeing.

Before I started learning/studying EFI and the JTEC/NGC PCM through my own tuning and also in porting TBs for others, I was very into carb tuning for atvs/dirtbikes, motorcycles etc. A change in vacuum/backpressure would affect both areas that you describe, but it was because the carb was no longer jetted properly.

I am tempted to say that the above scenario sounds like a MAF-based system issue? Not MAP like the Jeeps.

From what I have seen the NGC PCM's do not as much of a capacity to adapt. They appear to be more fixed in their WOT fuel tables (i.e. you add a modification, the PCM will often not adapt much if at all to the newfound airflow, meaning a leaner WOT AFR) . The JTEC/JTEC+ seems to behave much differently in that regard.

I understood most things you said, not sure what NGC and JETC/JETC+ is though. Basically what I think you are saying is my cars PCM does not have the ablity to adapt that much from stock settings?? And if so would a flash help, or anything else for that matter? Like I said before, I dont plan on doing anything else to the motor but want what I have done to it working in "perfect" order if possible. This is the first vehicle I have ever done mods to, and have always had great luck with my previous cars running great and lasting long with just the basic oil changes and minor repairs.
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  #24  
Old 11-25-2009, 04:52 PM
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Re: Gains/Losses w/SRT exhaust on WK 3.7?

timmy - sitting in the back seat is very different!!! i just tried it and i was like HOLY CHIT its LOUD back here lololol... needless to say i'll be doing some work in the rear cargo in the spring
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