273 4bbl dyno results

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Jarmo72

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Original 273, 4 bbl with std bore, original pistons, .010 over size fitted rings.
Comp Cam 20-221-3 with hydraulic lifters, std heads, Flow tech headers and original Carter 4294 S carb.

242Hp /5300rpm, 263lb-ft /4000rpm

View attachment WP_20160112_12_27_51_Pro.jpg
 

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Stock intake ??
Not bad for slightly over stock
 
Sorry, I missed intake manifold. Naturally it is also original, cast iron, heavy piece of history.

During the past they said that your garage build has been succeed if you don't loose more than 10% compared stock power/torque.
 
Nicely done. All of us 273 fans have been waiting for someone hook one up to a dyno. Nice numbers and quite a flat torque curve too. tmm
 
Very nice. How many RPMs did ya'll turn it? Is that Carter the one with the small bolt pattern? It would be interesting to see the numbers with a good aluminum intake and a bigger carb.
 
Very cool! Id love to strap mine on a dyno. Dont know of any engine dynos around my neck of the woods just chassis dynos.
 
That seems pretty good. According to the "stuff" over at Hamtramck Registry, the 67 273 was either 180hp at 4200, or 235 hp at 5200

http://www.hamtramck-historical.com...hipDataBook/1967/67_Dodge_Engineering0005.jpg

116hrnr.jpg
 
Very nice. Thanks for posting.

Will give ya 200 rear wheel HP easy. That's plenty for a lite early a body to be very quick & street-able.

Oldschoolcuda
 
Great info. Is your 273 a Commando ie. 10.5:1 compression and dual point distributor? The factory specs on the Commando/Charger rated 235HP with solid lifters. Where do you think the HP gain came from on your engine? The OPEN headers are probably the biggest help. However, I don't think headers are a big HP gain over the stock Commando exhaust manifolds/exhaust system when either one is run through legal mufflers and all the plumbing. I would love to see what the dyno reads with stock manifolds with open exhaust or the headers choked down with mufflers. I'll bet there is not a nickel's worth of difference between the 2. Chrysler thought so too with the 273 Commando and larger single exhaust. 340 and up is a different story. If Porsche could get 235 BHP out of a 2.7 liter, 2v, single exhaust engine in a 1973, stock 911S; we should be able to get 391.66667 BHP from a 4.5 liter Commando V8.
Just got a 67 Formula S, 4sp with a monster 340, 2x4bbl. I want to go back original with a stock Commando 273 with the refinements required to get close to 275HP on pump gas and stock hi-po exhaust system. Reckon blueprinting, porting and polishing would get me there? Thanx y'all for your expertise.
 
Very nice. How many RPMs did ya'll turn it? Is that Carter the one with the small bolt pattern? It would be interesting to see the numbers with a good aluminum intake and a bigger carb.

I bet you would see at least another 20 hp
 
When I swapped on (& made fit my early heads) my ld4b intake in place of stock iron intake power improved in all rpm levels. Pulls harder for sure in the midrange & top end. Fine tuning via wideband made even more diffrence! Very snappy/ torquey little 273! Glad to see them being brought back to life there a fununderestimated mill!
 
YEA !! Now I don't feel so bad about leaving the 273 in the Valiant.
 
Those are good numbers, we all get caught up with the 400-500 hp numbers but I wonder at what HP/TQ is it wasted on the street. Once you have enough to fry the tires anything after that is wasted Imo lol I have Mike at MRL working his magic on a 340 for my dart. Can't wait!
 
I was sure that, there is numbers of 273 lovers, like me. That's why I post my results.
Some added infos of my build. I try to keep my Barracuda as original as possible, only updates at the engine is Cam with hyd. lifters, headers and elect. ignition, new timing set and new oil pump.
All the rest, original build on the December 1966. ( 273, 4bbl).
Crank, connecting rods, pistons all original (bore 3,630" .010 cast piston rings didn't fit, those need to be fitted, heads only guide bushings, stronger valve springs added. Also original intake and 4294 S Carter cleaned and tuned. Off course all bearing surfaces has been checked and all what is needed has been changed, but basically it was quite easy rebuild.

I believe that I could have even better results, but cylinder bores were little conical on the top (about 1/2" down from deck level) , so I am loosing compressions. Don't know why those are like that, I mean so deep, just on the edge of the compression ring. Also heads gasket is oversized ( I ordered gasket set what match for 273,318 and 340cid) so I loose compression there as well. I don't know can I get anymore correct gaskets?
 

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I was sure that, there is numbers of 273 lovers, like me. That's why I post my results.
Some added infos of my build. I try to keep my Barracuda as original as possible, only updates at the engine is Cam with hyd. lifters, headers and elect. ignition, new timing set and new oil pump.
All the rest, original build on the December 1966. ( 273, 4bbl).
Crank, connecting rods, pistons all original (bore 3,630" .010 cast piston rings didn't fit, those need to be fitted, heads only guide bushings, stronger valve springs added. Also original intake and 4294 S Carter cleaned and tuned. Off course all bearing surfaces has been checked and all what is needed has been changed, but basically it was quite easy rebuild.

I believe that I could have even better results, but cylinder bores were little conical on the top (about 1/2" down from deck level) , so I am loosing compressions. Don't know why those are like that, I mean so deep, just on the edge of the compression ring. Also heads gasket is oversized ( I ordered gasket set what match for 273,318 and 340cid) so I loose compression there as well. I don't know can I get anymore correct gaskets?

Bores are just wear. You can hone with torque plates and straighten and round them back again, but the bore gets bigger. Most people won't take the time and patience to go that route. Too big and you are into new pistons. Ahhhh, the early MOPAR rebuild. Rings, bearing, gaskets, timing chain, exhaust valves, and a valve job. Don't try that with a Chevy. More power, throw in a cam, lifters, and matching valve springs. I always run Fel-Pro gaskets, they never leak or blow out. Good job!
 
Cometic will make head gaskets in the bore dia you request. The fire/seal ring will be at the normal 4.1somthing dia but added material to fit our little bores. Thats what I did they were a little pricey but nothen custom is cheap & there MLS gaskets. Make sure surfaces are really smooth & let er rip! Thanks again for posting! Sweet little motors indeed!
 
My build is sort of similar. Crower hydraulic with .427 lift and 264º duration (stock springs). .030 over with TRW hypereutetic pistons. Stock manifolds and carb. I have almost 90K on this combo, with 2.5" dual pipes. My recent freshen-up involved ported heads, but it hasn't made it back into the car yet.
 
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