225 /6 Build

[Centpiece]

Good Morning FBBO!! I have a question regarding the leading tower of power.. I'm in the process of restoring a 69 Charger that came stock with a /6 3-tree set up. After kicking around the idea of a 440 swap, but then seeing how many MOPARs out there that have been changed to the 440 RB, I have decided to keep the original set up in my Charger. I have read a lot of literature about building up the 225 for more power, but has anyone here in FBBO actually built a 225??

Initially, I'm thinking of a total rebuild, minimum overbore, good pistons/rods, 318 valves, 4bbl intake and header exhaust. Ultimately, I would like to run a supercharger and fuel injection set up, but that is in the distant future.. Not sure how difficult it would be to do while keeping the engine bay as clean as possible..

Not looking for insane HP, just a good bump..

Luckily there are plenty of Bone Yards here in San Diego... Lots of parts to be had..

 

[Meep-Meep]

First of all thank you for keeping the leaning tower of power! And second, yes, you can put more pep in your step with a few simple mods. Look up Doug Dutra. He builds these and sells a nice set of split exhaust manifolds. Ideally, on a 1-5-3-6-2-4 firing order you would split the intake as well. Or put a turbo on it. Lot's of room on that side for a compressor of sorts. FBBO member DPStark2 has a hoped up /6 in his Dart and I'm sure he will chime in when he sees this.

 

[Photon440]

Welcome, and good luck with the /6 build. I'll be watching...

 

[Badvert65]

If you are going to supercharge it, leave the compression alone. If not, shave the head to bump up the compression. That and bigger valves (plus porting) will make a big difference. Lots of good info on building up the slant six.

 

[mopar 3 B]

Bolt a turbo on and go to the 4 bl intake.

 

[Centpiece]

I see, I have a few things to move around in the shop, but looking to tear into the engine soon. Will break out the camera for pics shortly.. Thanks thus far for the engine tips..

 

[dpstark2]

Doug Dutra built my engine with my requirements in mind. I'm running an overdrive manual behind it and fairly steep gears. It's intended to be a commuter. We ended up at 9.1:1 with a pretty small cam and 318 size valves (I think). The motor pulls incredibly well from 1200 rpm or so to about 4k- and that's it. That's all I wanted. You can go several directions, so the best thing is to decide what you want: a hot rod 6, a fun driver, a commuter... you have to figure out what you want.

For simplicity, I'd try to go with a super six 2bbl setup, or a 4bbl. I'm currently running a split Offy manifold with 2x 1bbls- it works fine, but the linkage is a pain I have yet to figure a decent choke system. The dual manifold definitely works, but I think you can get nearly there with a single 2bbl. Splitting the exhaust manifold is a must- either using the stock rear half and Dutra front, or two Dutra manifolds. I made my collector system for dual Dutra manifolds for about $100. The entire exhaust- 2.5" out the back- for around $220 or so including muffler.

If you haven't checked out the slant 6 forum, it has a lot of resources and builds cataloged.

 

[dvw]

A slant six Charger is definitely different. However a 225 in N/A motor in a 3600lb car is going to be a turd. A turbo would work. But lets face it the 225 has no bore size or cubic inch. The head even ported with big valves is poor at best. It will be very slow even hopped up. Now if you don't care if it's slow, go for it. But don't waste money hopping up the 225.
Doug

 

[Photon440]

Hi Centpiece - good luck with the Charger build! Because of the lighter cars, you'd likely find more /6 info on FABO than here, so take a look at this example for slant six performance:
http://www.forabodiesonly.com/mopar/showthread.php?t=197489

 

[SublimeSixpack]

Glad to hear you're keeping the Slant six! Good luck with the build, and let us know how things work out. I've seen (and owned) a lot of Mopars through the years but never a Charger with a slant six in the engine bay.

 

[nm9stheham]

I just finished my /6 rebuild in almost totally stock 1 BBL form (for our very original '62 Dart).
I think with your car's weight, I would 2nd the suggestion above to head towards a turbo with limited boost (maybe around 8-10 lbs); it ought to be pretty peppy; that is the same ballpark for weight and boost in the 3.5L Buick turbo V6's in the mid-80's and they were decent cars.

Make the decision for turbo or normally aspirated up front; with the turbo, keep the stock compression and the valves and port work don't matter all that much. And you can make a U-pipe from the stock exhaust manifold right up into to the turbo and save a lot of work. With limited power increase, you can not bother with any intercooler (makes things even easier) and have more options for the carb/fuel setup. I personally would go for a throttle body EFI over a carb for this but all of this has been done so there is good info already.

For NA, the porting and large valve work has to be well done to get much extra power. If for the street, don't succumb to the temptation to go wild on the cam; you will likley get caught between poor bottom end torque and the limits of the /6's upper RPM head flow and have a crappily limited RPM range.

The earlier cranks are forged and the rods are reported basically good for all but the highest HP levels. Even the later cast cranks seem to be fine. The later heads (post '8 or so) are desired.

By far the most complete /6 info is on www.slantsix.org. Doug Dutra is there as 'Doctor Dodge'. Read the articles accessible via the site home page; there is one on the cylinder heads alone for example.

Have fun with it; I never heard of a /6 Charger!

Merry Christmas!