Tossing Around 273 Ideas

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64 SRT8 Dart

64 SRT8 Dart

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So, I still have the 273 laying around after swapping in a 318 to the long gone Valiant and have been pondering some builds.

Been thinking of a turbo/twin turbo build just to see what kind of power the little guy would make. Not sure what I'd put it in....maybe a sand rail? Dune buggy?? lol Little Ram50??? There we go....the Ram 50!!!

I would beef up the rods with some H beams. Use the factory forged crank. Order some custom forged 9 or 10:1 pistons.

Not sure about cam, what would be a good cam for this little guy?

Would use a 318 head with the 1.75I/1.5E and maybe put a bigger E valve...1.6 in it to help get exhaust out?? A good heavy port/polish/bowl clean up. Actually, wonder how a magnum style head would do?

Not sure about intake/carb combo. I'm sure I could build a custom sheet metal intake with injector bungs and maybe run FAST XFI system on it. LOL That would be cool!!

Prob run a 727 but could build a stout 904 to handle it...I have both lying around, lol.

Wonder what this little guy would run in a 1/4 in a Ram 50 with an 8 3/4 rear w/3.73 or 3.91's with leafs and caltracs??

Guess I 'm just doing some bench building/racing but.....what's a man to do at 4am while he's wide awake and his wife is sleeping? :)
 
Most built engines make 1:1-1.2:1 hp/cid and peak respectively from 5000-6000 rpm to reach the higher end will need some head work. If looking for more power more rpm or some power adders are needed. Magnum heads with notches would probably be a good step if looking for 350 hp or more.
 
The 50 plus desktop dyno 273 I've tried most of them liked the comp cam 268 solid roller.
 
273, I was thinking roller as well....after I logged off, lol. There is a 88 Ram 50 on CL right now that looks clean and straight as a whistle for $1500.

Wonder how the stock 273 920 castings would work with a valve upgrade? Chambers are closed. I have that set as well.

Was thinking of sticking with a smaller valve to keep from having to notch the bores....not sure how they'll hold up under boosted applications?? Letting the forced induction do the work of the bigger valve....sort of, lol.
 
I imagine the intake side needs the notch. I'm suprised Ma Mopar didn't use a 1.60 exhaust valve anyway.
 
I could prob get a way with the 1.88"/1.60 set up as that equals 3.48" worth of space in the 3.625" bore. The block I'm sure needs a min of .030" to clean up anyway so bore would be a min of 3.655". This gives roughly 3/32" on either side of the valve in the bore but that's if the chambers/bores are sharing the same theoretical center line. Who knows what it would be with core shift. lol Wouldn't have to notch too much I guess.
 
64 SRT8 Dart said:
I could prob get a way with the 1.88"/1.60 set up as that equals 3.48" worth of space in the 3.625" bore. The block I'm sure needs a min of .030" to clean up anyway so bore would be a min of 3.655". This gives roughly 3/32" on either side of the valve in the bore but that's if the chambers/bores are sharing the same theoretical center line. Who knows what it would be with core shift. lol Wouldn't have to notch too much I guess.
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Don't forget to add the space between the valves

Notching shouldn't be a big deal I was thinking of notching even with stock valve pretty tight in there.

When I thought about doing mine I was gonna use ford 1.8?-1.55 cause thinner stems can get valves that are undercut in the port plus big enough to be on new meat so not to sink the valves.
 
Hard to beat boost... but you do build differently when using boost. I've experienced what 14 psi does with a 4cyl, and I've seen V6's in 3800 lbs regals go 10's on 24 psi, so if you add boost to that 273, it will rock!
 
If one were to build a TT273 what size of carb and turbos would be adequate for use?

Cam would be a solid roller in the mid. .500's in lift. 110CL and 230ish at .050. Heads would be either 318 or 360 with 1.88/1.60 valves.

How about a 650 with two 58mm turbos? Too much turbo?
 
Im planning on throwing a T64(?) On a 2bbl 273 with stock pistons to see what itll do. Easy draw through setup, then maybe a blow through efi. Lots of projects, so little time. 340 bushed rods on the 273 pistons and maybe a 360 damper all balanced together...? No need for high compression pistons with a turbo.
 
I would not even bother with bigger valves with any first level boosted setup; it will indeed overcome the valve size, not any problem at all. I'd put my $$ into good forged pistons and good bottom end parts. Maybe 8:1 SCR (open chamber heads), then a good intercooler.

Why not go single turbo and keep it simpler? You're going to make plenty enough power to quickly find that traction on a Ram50 is going to be the main problem, not torque and power; 14-15 lbs boost will get you up into the 400+ HP range with 273 ci without hardly trying.

Draw through has the carb before the turbo, blow through has it after. Draw through means any carb is set up normally; blow through means it has to have items to make the carb pressures equalized to boost at places like the bowl vents and the fuel inlet, to keep the boost from blowing back out these points. Draw through puts the fuel air mixture through the compression process, with has some particular problems like cold starting and keeping the fuel in suspension throughout the long passage from carb to cylinders; blow through gets around those issues.
 
Watch the compression. Milling blocks and surfacing heads along with 920's and you might have upwards of 10:1 or a bit better. Not good with boost.
 
Thanks guys for the info!

tmm, I have a set of open chamber 318 heads sitting as well. I've been following 318willrun's thread on the 318 and will probably at least do what he's done to em.

I might just have the 920's rebuilt and sell em to get a little extra $$$ for the rest.
 
BTW, I ran 8.2:1 CR for several years on a rally car with a 14-15 psi boost limit; that particular combo would detonate at boosts up around 17-18 psi with pump premium fuel; going higher on boost would have required non-pump fuel mixtures. So that is one reference point for a limit to the boost vs SCR. The 8.2:1 SCR made the 'before-boost-comes-on' performance to be a LOT better than at 7.6:1 SCR or 7.2:1 SCR which I tried in the same engine. So getting that SCR versus boost limit balance correct is important, in my experience and in that application, which is what might be characterized as mixed street and endurance racing.

Is this setup going to mainly emphasize drag racing? That makes the choices a bit different, IMHO.

Also, there are a lot of different turbo designs and just small tweaks in the exhaust side wheel can make a big difference on how the turbo comes on at low RPM's. So I would do a lot of reading on that over on the 4 banger turbo forums; they seem to pay a lot of attention to that aspect.
 
64 SRT8 Dart said:
Wonder what this little guy would run in a 1/4 in a Ram 50 with an 8 3/4 rear w/3.73 or 3.91's with leafs and caltracs??

Guess I 'm just doing some bench building/racing but.....what's a man to do at 4am while he's wide awake and his wife is sleeping? :)
Click to expand...

Hmmm
maybe visit :D< click the toothy grin
 
64 SRT8 Dart said:
If one were to build a TT273 what size of carb and turbos would be adequate for use?

Cam would be a solid roller in the mid. .500's in lift. 110CL and 230ish at .050. Heads would be either 318 or 360 with 1.88/1.60 valves.

How about a 650 with two 58mm turbos? Too much turbo?
Click to expand...

Call a turbo guy,before ordering a cam on those specs... Overlap,has it merits,bleeding boost out the tailpipes, doesn't help the combination very well. 112/114 lobe centers,help well here,do some digging & research first. (273 builds,don't need big cams,unless spinning huge R.P.M 'S) Just my opine,on limited knowledge..
 
I got an LA turbo grind cam that i could try and spec for our audience here for some comparison. A pair off a 2.2 would work and be close to the cfm/cid design of the popular 2.2. But 2 is twice as hard to build as a single larger turbo.
 
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