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Old 11-16-2010, 11:36 AM
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STR8 headers vs stock log exhaust

Full SRT8 exhaust really woke up my 09 WK 5.7 Look how restrictive the stock manifolds are. I now run 14.20 @97mph with the above exhaust and predator 93 tune and K+N CAI and 180 stat. Not too shabby for a porky 4400lbs!!
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Old 11-16-2010, 11:44 AM
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Re: STR8 headers vs stock log exhaust

more...
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Old 11-16-2010, 12:14 PM
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Re: STR8 headers vs stock log exhaust

Definitely a step in the right direction
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Old 11-16-2010, 12:38 PM
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Re: STR8 headers vs stock log exhaust

Damn I wish we 4.7 guyz had that option ...
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Old 11-16-2010, 01:01 PM
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Re: STR8 headers vs stock log exhaust

I am very impressed with the 5.7 hemi. Heads seem to flow very, very well and I want to do more mods to my jeep. I would like to look into the benefits of the srt8 intake compared to the stock 09. And larger throttle body as well. This engine has 10.5-1 compression and has never knocked so I think I may look into a more aggressive CMR tune....... TBF
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Old 11-16-2010, 01:29 PM
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Re: STR8 headers vs stock log exhaust

Not shabby at all...
Congrats on getting it running so good.
Is that 14.2 at the track? Impressive!
You might be the first one to dip N/A into the 13s, maybe with a more aggressive CMR tune alone without doing anything else. You are running the 93 CAI canned tune right?
Not sure an SRT8 stock intake would help, a polish/ported one I'm sure it will.
What headers are are you running?
Keep up the good work and keep us posted. Hopefully you'll get into the 13s soon, I'll be in the look-out for that.
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Old 11-16-2010, 01:39 PM
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Re: STR8 headers vs stock log exhaust

cut some weight out and youll be there.....


take a look at the PPP race ported heads
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Old 11-16-2010, 02:49 PM
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Re: STR8 headers vs stock log exhaust

Ive done some research, and the 09 intake vs the srt8 intake is very small, something like only 2 cfm more from the SRT.

I'd say do as scott mentioned and look into 09 ported heads. We should find a vendor because i've been wanting 09 heads so I can run SRT headers.

Or get a cam, and tune, and youll be in the 13's with ease
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Old 11-17-2010, 09:16 AM
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Re: STR8 headers vs stock log exhaust

I will probably do the heads a bit down the road and a cam for sure if I end up pulling the heads. I just emailed Johan about a custom tune as i am pretty sure the diablosport 93tune leaves a bit of power on the table. That plus a set of slicks should get me in the 13,s pretty easily as my 60ft times were 2.2 and this was at bradenton with air temp in the 80,s..... For us 5.7 guys, I would not hesitate to buildup these motors. Not really much difference in engine size (345 vs 370) so only about 30-40hp less for any given combo. 09 and later heads are the ones to use and fully ported probably are pretty close to srt8 heads with the larger chambers. I figure a well built 5.7 motor could make 450-470hp all day long and run on 93 octane. Even with the cast crank/pistons, that power level should not be a factor in reliability if rpm,s are kept around 6K max..... The bottom line here is that the best mod you can make for a 5.7 is to go with a free flowing exhaust and the srt8 setup is just about optimium. That made the most difference for me. Just look at how those stock manifolds choke the flow....... I will get this bitch into the 13,s with just bolt ons for sure..... just might need a cold day to do it! TBF
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Old 11-17-2010, 01:03 PM
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Re: STR8 headers vs stock log exhaust

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Originally Posted by tpabayflyer View Post
I will probably do the heads a bit down the road and a cam for sure if I end up pulling the heads. I just emailed Johan about a custom tune as i am pretty sure the diablosport 93tune leaves a bit of power on the table. That plus a set of slicks should get me in the 13,s pretty easily as my 60ft times were 2.2 and this was at bradenton with air temp in the 80,s..... For us 5.7 guys, I would not hesitate to buildup these motors. Not really much difference in engine size (345 vs 370) so only about 30-40hp less for any given combo. 09 and later heads are the ones to use and fully ported probably are pretty close to srt8 heads with the larger chambers. I figure a well built 5.7 motor could make 450-470hp all day long and run on 93 octane. Even with the cast crank/pistons, that power level should not be a factor in reliability if rpm,s are kept around 6K max..... The bottom line here is that the best mod you can make for a 5.7 is to go with a free flowing exhaust and the srt8 setup is just about optimium. That made the most difference for me. Just look at how those stock manifolds choke the flow....... I will get this bitch into the 13,s with just bolt ons for sure..... just might need a cold day to do it! TBF
Not following you here bro. How did you end up getting the 30 to 40 hp less?
345 and 370 like you said is the size of the motor not hp, horsepower between the two is 330 hp for the '05 to '08 5.7L and 357 hp for the '09 - '10 5.7L. The SRT8 is 420 hp (as advertised to the crank numbers).
I do agree with you, the 5.7L has so much more to offer and starting with the intake and exhaust areas make a huge difference once you upgrade them. Just look at the LX guys how much they have accomplished out of the 5.7Ls. And now with CMR tuning available for the 5.7L Jeeps, there's so much more you can do to it. I'm surprised no one has gone crazy with a 5.7L jeep as the LX guys had with theirs.
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Old 11-17-2010, 04:10 PM
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Re: STR8 headers vs stock log exhaust

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Originally Posted by QBNKID View Post
Not following you here bro. How did you end up getting the 30 to 40 hp less?
345 and 370 like you said is the size of the motor not hp, horsepower between the two is 330 hp for the '05 to '08 5.7L and 357 hp for the '09 - '10 5.7L. The SRT8 is 420 hp (as advertised to the crank numbers).
I do agree with you, the 5.7L has so much more to offer and starting with the intake and exhaust areas make a huge difference once you upgrade them. Just look at the LX guys how much they have accomplished out of the 5.7Ls. And now with CMR tuning available for the 5.7L Jeeps, there's so much more you can do to it. I'm surprised no one has gone crazy with a 5.7L jeep as the LX guys had with theirs.

Mario he is referring to displacement not hp numbers... And he is right in the sense that all things equal, the extra 25 cubes will only yield about 40 hp extra.

Displacement is the key to making power, but it's not what exactly makes it...It's all in the cam profile, headwork, and intake/exhaust systems...

03-08 heads seem to be the ones to use for all but the most extreme builds, with big valves they flow more than enough air to support a stroker motor, with the benefit of higher port velocity. Which is what you want with a built motor in a heavy truck (4000+ lbs). I have yet to see any hard data that indicates that 09 heads yield to better ETs (notice how i did not say better flow bench readings or peak HP/TQ numbers). CFM is only part of the equation.
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Old 11-17-2010, 10:09 PM
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Re: STR8 headers vs stock log exhaust

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Originally Posted by FlyinRyan View Post
Mario he is referring to displacement not hp numbers... And he is right in the sense that all things equal, the extra 25 cubes will only yield about 40 hp extra.

Displacement is the key to making power, but it's not what exactly makes it...It's all in the cam profile, headwork, and intake/exhaust systems...

03-08 heads seem to be the ones to use for all but the most extreme builds, with big valves they flow more than enough air to support a stroker motor, with the benefit of higher port velocity. Which is what you want with a built motor in a heavy truck (4000+ lbs). I have yet to see any hard data that indicates that 09 heads yield to better ETs (notice how i did not say better flow bench readings or peak HP/TQ numbers). CFM is only part of the equation.
Ryan, I know he is talking about the displacement as I mentioned to him above. I just want to know where the 40 hp extra comes from the extra 25 cubes. How do you guys come up with 40? Fill me in...
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