Need help, R3 vs Hemi, 6.1/6.4,,turbos??

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1970boy

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Want to start gathering cash for parts for a future build. Currently have a 68 fastback barracuda with a 340, 340 has a very mild cam just a touch above stock, LD340 intake and a afb 1406 carb, exhaust manifolds are TA hi-po manifolds. Question is for what I want to achieve whats the best route to go, most efficient and cost effective. In the end I want to be able to compete with hellcats on the street and at the strip, how would you go about a build like this? I like the idea of turbos and I hear the newer hemi’s would be better but I like my 4 speed trans and also the idea of an older engine taking on a newer one and winning. Thoughts? Losing the 4 speed isn’t a deal breaker, just want a car that is streetable and also able to compete and show some hellcats the taillights on my 68 barracuda
 
a Gen 3 with a pro charger would be sweet .
 
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According to the interwebs your benchmark will be mid to high 11s in the 1/4 mile as that appears to be where stock Hellcats run. That's not too crazy. Look over on the racers forum and read about different combos that run in the 11s.
 
Your 4 speed bell housing will bolt to a G3 Hemi. Top center bolt in BH not used though.

The way I look at is.....a built 340 with 400 true HP at the flywheel will sound like a built 340. Kinda radical and not good MPG on premium fuel.

A 5.7 Hemi with just a mild cam and headers is easily 400 +. And it sounds like an everyday modern Challenger. Bonus, it's lighter than a small block by 70 lbs or so.

Try that and if its not enough, you can turbo or supercharge later.
 
KosmicKuda said:
Your 4 speed bell housing will bolt to a G3 Hemi. Top center bolt in BH not used though.

The way I look at is.....a built 340 with 400 true HP at the flywheel will sound like a built 340. Kinda radical and not good MPG on premium fuel.

A 5.7 Hemi with just a mild cam and headers is easily 400 +. And it sounds like an everyday modern Challenger. Bonus, it's lighter than a small block by 70 lbs or so.

Try that and if its not enough, you can turbo or supercharge later.
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Good to hear the 4 speed would work with it, I like the idea of a Hemi but is the a big difference in aftermarket parts for the Hemi vs the 340? Also I prefer the sound of a 340 is there a way to replicate that with a Hemi?
 
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Boost on Modern Hemis is limited to 8lbs. Anything beyond that and you are taking a chance of a rod moving to another place. I had a 6.4 with a supercharger and water meth kit.. Was fun for sure and was quick. Was it fast to me.... No... If you want to go fast and save some money put an LS in it with a turbo on 12lbs. No issues at all and the car would probably run in the very low 10 to high 9's depending on if it hooks or not. With this said I am building a 67 Fastback Barracuda with a 408 and twin turbos. Mine will be blow through carb for now with a F1 upgrade in the future.
 
Stock Gen 3 hemi pistons are good for about 7 PSI due to the pistons being cast, tight ring gaps and compression ratios over 10 to 1 (6.1/6.4). Affordable lower compression ratio forged drop in pistons are available from mahle so you can reliably increase the boost into the double digit range.

Many of the reported piston failures are related to tuning or a lack of. The factory (SRT) computers cannot be tuned to compensate for part throttle boost which means they are running lean at all boost levels with the exception of WOT.

The factory blocks and forged cranks have proven to be reliable into the 800 HP range.

The airflow on the factory 6.1 and 6.4 heads pretty much blows every LA/small block head out of the water.

In regards to sounding like a 340, I installed an Arrington SR-2B camshaft into my 6.1 SRT8 charger and it now has an awesome muscle car idle. This cam with a tune added roughly 40 HP over stock but probably isn’t the right profile if you plan on running boost.
 
I ran 8lbs of boost on my stock 6.4. My car was built by Arrington and tuned on their dyno with a water meth kit.It can live on 8lbs.. but that is the edge.. Get a 6.1 and put the 426 stroker kit in it. Great motor and allot of HP made from these. Arrington has everything along with Modern Muscle.
 
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