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Discussion Starter #1
Hi Everyone!
Here is my build.

I am the first owner of my 2012 Challenger R/T Classic. She has a 6-speed transmission with a McLeod RST dual plate clutch I just installed, as well as 3.92 rear gears.

Now the fun part,
Since I have had the car I have done pretty much every bolt on.
K&N CAI, 85mm BBK throttle body, kooks long tubes, kooks midpipes with cats, pypes violator cat-back, 180 degree t-stat.

Then I opened her up and did some on the inside, I bought a set of ported and polished cylinder heads from Arrington (would definitely recommend doing business with them!), chromolly pushrods, as well as my COMP 270 cam with phaser. Heads came fully assembled with new valves, better springs and retainers to be able to handle the higher RPM range of the 270 cam. (I also changed my timing chain and gear when I changed my cam at 50,000mi for good measure)

Numbers?
Well I'm making this post because I had a diablosport email tune for the longest time but I took it to SeriousHP in Houston a few weeks ago to get a proper HP tune.
I'm happy to say with the mods I have done, she put down 407.39 RWHP at 6,280 RPM and a respectable 397.38 TQ at 5,020 RPM. (redline is now 6,500)

Now I know she isn't the meanest challenger on the block, but I have done all the work myself and am proud to say she runs like a champ at ~86,000 mi. Please ask any questions you have for me.
996670

996671
996673
 

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2016 R/T Scat Pack
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Proof the small hemi can make big power!! Does that cam have any lope to it?
 
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2015 SRT 392
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Congratulations on both the new power and for doing it yourself! Looking at your dyno chart, there is good power under the curve for a relatively mild cam too. With the new power along with those rear gears, I'll bet she's a blast to drive!

Those are Good numbers too, especially with the rear gear that you have installed. If I remember correctly, a rear gear can make your power numbers lower but make a HUGE difference on the street!

Please Drive Safely! (y)
 

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The Pork Wagon (‘14 Cop Charger)
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Have you considered swapping out the 5.7L intake for one with the dual runner design (AKA active intake?), like what comes stock on the 6.4L engines?

They will switch their runner length from long to short right at the point your dyno shows you have maxed out torque, so it could enable the engine to add a little more top end power above 5K RPM.

I’m sure you’d have to get your custom tune modified to take full advantage of it, but it might be worth looking into for your next power-adding mod.

Good job so far either way though. Very impressive you have been able to do all the work yourself! (y)
 

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Discussion Starter #5
Proof the small hemi can make big power!! Does that cam have any lope to it?
Thanks! And oh she sure does. My instagram is "themikecitydon" and I have a video on there of before and after the cam if you'd like to see it. Sounds better now that I changed my short tubes for long tubes!
 

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Discussion Starter #6
Congratulations on both the new power and for doing it yourself! Looking at your dyno chart, there is good power under the curve for a relatively mild cam too. With the new power along with those rear gears, I'll bet she's a blast to drive!

Those are Good numbers too, especially with the rear gear that you have installed. If I remember correctly, a rear gear can make your power numbers lower but make a HUGE difference on the street!

Please Drive Safely! (y)
Thank you! I have poured many hours into her but I really am impressed with the numbers so far. At about 3500rpm though it just blows off the tires, those 3.92 rear gears are no joke in 1st and 2nd.

And you are correct. Tuner said I would have made more power with 3.73 but I wouldn't change a thing.

Stay safe as well!
 

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Discussion Starter #7
Have you considered swapping out the 5.7L intake for one with the dual runner design (AKA active intake?), like what comes stock on the 6.4L engines?

They will switch their runner length from long to short right at the point your dyno shows you have maxed out torque, so it could enable the engine to add a little more top end power above 5K RPM.

I’m sure you’d have to get your custom tune modified to take full advantage of it, but it might be worth looking into for your next power-adding mod.

Good job so far either way though. Very impressive you have been able to do all the work yourself! (y)
Thank you! I'm fortunate enough to have a shop at home with a lift so that definitely makes life easier.

I have considered the dual plane intake for my car but I didnt want to loose any torque down low. I think she is breathing pretty good at the moment.

I plan on doing a procharger in the future though so maybe that will be the right time to do it 😎.

For my next move I'm thinking about doing some mods to my suspension so I can get it to hook up better before I add mo-powa-baby.
 

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Proof the small hemi can make big power!! Does that cam have any lope to it?
There is plenty of proof they can....just look at some of these dynos from old builds.
 

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Discussion Starter #9
There is plenty of proof they can....just look at some of these dynos from old builds.
Aww Chally, he thought my car made power! Now all these builds stealing my thunder 😂😂.
 

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The Pork Wagon (‘14 Cop Charger)
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Thank you! I'm fortunate enough to have a shop at home with a lift so that definitely makes life easier.

I have considered the dual plane intake for my car but I didnt want to loose any torque down low. I think she is breathing pretty good at the moment.

I plan on doing a procharger in the future though so maybe that will be the right time to do it 😎.

For my next move I'm thinking about doing some mods to my suspension so I can get it to hook up better before I add mo-powa-baby.
The intake design the 6.4L engines use isnt a dual plane like what old school high rpm dragsters would run. It’s basically the same as the 5.7L intake (so no power lost down low), but it has a set of shorter runners also built in to make more power at high RPMs (where the long runners meant to make low end torque start to become a detriment). It has an electronic valve that switches all the runner paths at the same time at a predetermined rpm, which is 5K rpm usually.

It’s supposed to be the best of both worlds, low end torque and high end HP, and I suppose it is to some extent. It picks up where the 5.7L intake leaves off I guess is a good way to look at it.
 
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2010 R/T Classic 6M
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The intake design the 6.4L engines use isnt a dual plane like what old school high rpm dragsters would run. It’s basically the same as the 5.7L intake (so no power lost down low), but it has a set of shorter runners also built in to make more power at high RPMs (where the long runners meant to make low end torque start to become a detriment). It has an electronic valve that switches all the runner paths at the same time at a predetermined rpm, which is 5K rpm usually.

It’s supposed to be the best of both worlds, low end torque and high end HP, and I suppose it is to some extent. It picks up where the 5.7L intake leaves off I guess is a good way to look at it.
Not that it matters anymore since I'm getting boosted, but are the intake runners the same as the 5.7 at the top end or low rpm? I've heard both so I'm a little confused as to if it makes bottom or top end power
 

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Discussion Starter #14
The intake design the 6.4L engines use isnt a dual plane like what old school high rpm dragsters would run. It’s basically the same as the 5.7L intake (so no power lost down low), but it has a set of shorter runners also built in to make more power at high RPMs (where the long runners meant to make low end torque start to become a detriment). It has an electronic valve that switches all the runner paths at the same time at a predetermined rpm, which is 5K rpm usually.

It’s supposed to be the best of both worlds, low end torque and high end HP, and I suppose it is to some extent. It picks up where the 5.7L intake leaves off I guess is a good way to look at it.
Yea, I called it a dual plane just for the lack of a better term. Im sure she would pick up a few horses up top with shorter runners. I'll consider one when I go to boost for sure.
 

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Not that it matters anymore since I'm getting boosted, but are the intake runners the same as the 5.7 at the top end or low rpm? I've heard both so I'm a little confused as to if it makes bottom or top end power
The 5.7 has longer runners for the low rpm range and the srt8 has short runners it diverts to at high rpm. I doubt the longer runners in both are EXACTLY the same... but they gotta be close.
 

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The 5.7 has longer runners for the low rpm range and the srt8 has short runners it diverts to at high rpm. I doubt the longer runners in both are EXACTLY the same... but they gotta be close.
Gotcha, so the weak point of the 5.7 manifold is the top end. I was never sure which way it was because I've seen posts saying both.
 

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The Pork Wagon (‘14 Cop Charger)
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Gotcha, so the weak point of the 5.7 manifold is the top end. I was never sure which way it was because I've seen posts saying both.
I think it’s more of a case that the weak point of any stock single runner design is going to be the upper RPM range (>4500 RPM). The longer runners help the air charge gather speed as they enter the CCs, but at higher RPM that is unnecessary and even detrimental to Max VE.

At higher RPM, a shorter runner is best, but you can’t have it both ways in a stock manifold. So they opt for the low end maximum torque design for obvious reasons.

That’s where the dual runner design comes in - it allows longer runners and more torque at low RPM, and short runners and more HP at high RPM.

That’s an oversimplified way to look at it, but I think it gets the point across...
 
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Gotcha, so the weak point of the 5.7 manifold is the top end. I was never sure which way it was because I've seen posts saying both.
Yes Sir! This is why sportbike manufacturers can get away with using velocity stacks and individual throttle bodies. They are very short runners, but they are great for high RPM's. Opposite to the challenger rt manifold for example.
 

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The Pork Wagon (‘14 Cop Charger)
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Given that the engine is making so much more power up top where the stock one normally wouldn’t, I wonder if the exhaust size has become a restriction for the engine trying to completely expel the exhaust gases to make enough room for the incoming air charge.

Clearly the engine is breathing better as a benefit from the TB and head upgrades, so what about exhaling through the 2.5” pipes out back? Is that large enough now?

All theoretical, hardly testable without spending an arm and a leg, I know, but I can’t help but wonder... :unsure:
 
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Given that the engine is making so much more power up top where the stock one normally wouldn’t, I wonder if the exhaust size has become a restriction for the engine trying to completely expel the exhaust gases to make enough room for the incoming air charge.

Clearly the engine is breathing better as a benefit from the TB and head upgrades, so what about exhaling through the 2.5” pipes out back? Is that large enough now?

All theoretical, hardly testable without spending an arm and a leg, I know, but I can’t help but wonder... :unsure:
Honestly I'm not worried about exhaust scavenging. She has full length 1 7/8" primarys into a 3" collector for the long tubes. The mid pipes are also both 3". Then I welded reducers from the 3" to 2.5" for my x pipe and the rest of my exhaust.
It was an arm and a leg, but I doubt my exhaust is my limiting factor.
 
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