New idea for a 273 stroker

Posted By: dogdays

New idea for a 273 stroker - 09/23/11 06:48 PM

Funny how my mind works...

The NASCAR boys are using a lot of 0.866" pins to save weight. Consequently there are a lot of 1-race rods floating around with that weird pine size.

Today I was studying my KB catalog and came across the piston for a Toyota 22R. Bore is 3.622, available in oversizes. The piston weighs less than 400 grams and has a 0.866 pin. Compression height is something like 1.35"

Anyway I did the math and came up with an ideal rod length of 6.225". That's close enough to 6.200".

So it all fits in a 273 block and should rev easily, as long as you can find 6.200 rods with a 2.0 or similar crankpin size and pin of 0.866.

Anyone want to try? It's a 330.

R.

Posted By: scratchnfotraction

Re: New idea for a 273 stroker - 09/23/11 08:43 PM

very interesting indeed.

only 19 cubic inches behind a 360 crank in the 318 block for a 349 stroker.

Posted By: dart4forte

Re: New idea for a 273 stroker - 09/23/11 10:19 PM

I have a recipt for a destroked 273, 258CI

Posted By: convx4

Re: New idea for a 273 stroker - 09/23/11 10:25 PM

I got to ride in a de-stroked 318. It used the 273 crank. 305 CI like the Real Trans Am racers. I have an old mopar engine book with the build specifics. This motor was in a 69 dart. It would rev way up fast and blast off the line. This would help keep it in the winning position. I ways wanted to build one.

Posted By: Fat_Mike

Re: New idea for a 273 stroker - 09/23/11 10:40 PM

Very interesting indeed. Would these work?

http://www.roushyatesparts.com/parts-p/rye-b110007u.htm

Posted By: Locomotion

Re: New idea for a 273 stroker - 09/23/11 10:48 PM

Quote:

I got to ride in a de-stroked 318. It used the 273 crank. 305 CI like the Real Trans Am racers. I have an old mopar engine book with the build specifics. This motor was in a 69 dart. It would rev way up fast and blast off the line. This would help keep it in the winning position. I ways wanted to build one.

273 cranks had the same 3.31" stroke and journal diameters as 318's and 340's. The Trans Am cranks had something like a 2.96" stroke.

One problem with a stroked 273 is that despite the extra cubic inches, the bore size would limit valve size and breathing. I would think that it would make a lot more torque.

Posted By: scratchnfotraction

Re: New idea for a 273 stroker - 09/24/11 01:51 AM

Quote:

Quote:

I got to ride in a de-stroked 318. It used the 273 crank. 305 CI like the Real Trans Am racers. I have an old mopar engine book with the build specifics. This motor was in a 69 dart. It would rev way up fast and blast off the line. This would help keep it in the winning position. I ways wanted to build one.

273 cranks had the same 3.31" stroke and journal diameters as 318's and 340's. The Trans Am cranks had something like a 2.96" stroke.

One problem with a stroked 273 is that despite the extra cubic inches, the bore size would limit valve size and breathing. I would think that it would make a lot more torque.

torque rules for for fun factor

the whole point of a stroker..no?

I know my uncle had a stock hipo 273 with a .500 lift solid cam that was a beast for a 273 with 4-speed and 3.91sg and it would buzz real high rpms.

I am thinking a 330 or 349 would be real cool on the street as a daily driver and the 349 would not need the bore notching and could use 360 heads

Posted By: jcc

Re: New idea for a 273 stroker - 09/24/11 10:39 PM

Quote:

One problem with a stroked 273 is that despite the extra cubic inches, the bore size would limit valve size and breathing. I would think that it would make a lot more torque.

Relative to what, a 273, duh, a stroked 318, no, a stroked 340, no, a stroked 360, no. Stroking just makes more or less more torque realtive to hp, not just goobs of torque.

Posted By: Fat_Mike

Re: New idea for a 273 stroker - 09/24/11 11:04 PM

Quote:

Quote:

One problem with a stroked 273 is that despite the extra cubic inches, the bore size would limit valve size and breathing. I would think that it would make a lot more torque.

Relative to what, a 273, duh, a stroked 318, no, a stroked 340, no, a stroked 360, no. Stroking just makes more or less more torque realtive to hp, not just goobs of torque.

What I read into this recipe was a 273 with a few more cubes, and a light rotating assembly. So in a nut shell, it isn't necessarily building up a powerhouse 273, but building a well balanced 273 with a light rotating assembly that will spin up to 7.5, maybe even 8K RPM's. Therefore upping the HP, not just torque. Something that would work out great in an early A-Body. Aside from the "knowns" of what other motor combo's have proven, it would be interesting (IMO) to see the numbers this recipe would make.

Posted By: dogdays

Re: New idea for a 273 stroker - 09/24/11 11:31 PM

Thanks, that is where I was headed. Basically 273s and 318s are free engines. You can always build a bigger engine for about the same price. But, suppose you want a stronger 273 Dart with the original engine? Or suppose you have a free 273 block and dare to be different? Those rods are NASCAR quality and usually available for a couple of hundred $. The pistons are quite inexpensive and with pin about 200 grams lighter than a 273 piston and pin. 2.50 main stroker cranks are all over the place. Yes, the smaller bore limits head flow, but how much flow do you need with a 330?

Check back next week for the next installment of "dare to be different" stroker free blocks. Hint: What's 24mm got to do with it?

R.

Posted By: jcc

Re: New idea for a 273 stroker - 09/25/11 08:31 AM

Different? Take a 340, bore it .060, destroke it back to a final 273, use superlight pistons, use roller cam, wind it to 9800, drop the clutch and hang on, and blow away all the other 273's.

Posted By: A990

Re: New idea for a 273 stroker - 09/26/11 02:56 AM

Quote:

Different? Take a 340, bore it .060, destroke it back to a final 273, use superlight pistons, use roller cam, wind it to 9800, drop the clutch and hang on, and blow away all the other 273's.

Well since 273/318s are still in the JYs and the 340s have long ago disappeared, this is a great idea

I have a 65 block and heads in my garage begging to be put to use again.

One thing for Dogdays-

Wonder how a turbocharger would work?

Posted By: 69B3GT

Re: New idea for a 273 stroker - 09/26/11 03:09 AM

I still have the 273 out of my dart sitting in the garage

If I get another car id like to do something different

Posted By: scratchnfotraction

Re: New idea for a 273 stroker - 09/26/11 11:58 AM

Quote:

I still have the 273 out of my dart sitting in the garage

If I get another car id like to do something different

a little 273 with the hipo solid lifter cam at .500 lift is pretty nasty in a 66 dart with 4 speed and 3,91sg, my uncles would buzz right up around 6500 rpm and whooped up on some 327 chebby back then.

ask the Rev about his "class of 65" with the record holding 273,IIRC it still holding the record today.

now thats a little bad azz 273 right there

it can be done but you "gotta want it"

Posted By: 69B3GT

Re: New idea for a 273 stroker - 09/26/11 01:35 PM

Quote:

Quote:

I still have the 273 out of my dart sitting in the garage

If I get another car id like to do something different

a little 273 with the hipo solid lifter cam at .500 lift is pretty nasty in a 66 dart with 4 speed and 3,91sg, my uncles would buzz right up around 6500 rpm and whooped up on some 327 chebby back then.

ask the Rev about his "class of 65" with the record holding 273,IIRC it still holding the record today.

now thats a little bad azz 273 right there

it can be done but you "gotta want it"

Maybe one day ill get around to building a wild 273...just gotta get this big block car squared away..one of these days

Posted By: patrick

Re: New idea for a 273 stroker - 09/26/11 06:47 PM

Quote:

Quote:

Quote:

I got to ride in a de-stroked 318. It used the 273 crank. 305 CI like the Real Trans Am racers. I have an old mopar engine book with the build specifics. This motor was in a 69 dart. It would rev way up fast and blast off the line. This would help keep it in the winning position. I ways wanted to build one.

273 cranks had the same 3.31" stroke and journal diameters as 318's and 340's. The Trans Am cranks had something like a 2.96" stroke.

One problem with a stroked 273 is that despite the extra cubic inches, the bore size would limit valve size and breathing. I would think that it would make a lot more torque.

torque rules for for fun factor

the whole point of a stroker..no?

I know my uncle had a stock hipo 273 with a .500 lift solid cam that was a beast for a 273 with 4-speed and 3.91sg and it would buzz real high rpms.

I am thinking a 330 or 349 would be real cool on the street as a daily driver and the 349 would not need the bore notching and could use 360 heads

no, the whole point of a stroker is to add displacement...stroke is just a more convienient way to add displacement. one of the mags like hotrod a number of years ago built up 2 383ish cheby motors with identical components, save one was "all bore" with an aftermarket block and stock 350 stroke, the other was all stroke. compression was the same for both. the results? they made essentially the same power, with the "all bore" motor besting the stroker by a few HP/tq due to less valve shrouding. so your exotic, expensive 330CID 273 based stroker has the same HP/tq potential essentially as a .060 over 318....or less than a stock stroke 360....

the other issue with a 4" arm/6.2" rod (1.55 rod ratio) motor is piston velocity....with a stock replacement type cast piston, I wouldn't recommend going past 4000 ft/sec for a mean piston speed, which limits you to ~6000 RPM.

Posted By: Neil

Re: New idea for a 273 stroker - 09/26/11 07:18 PM

What sort of heads + intake would work good with a 'big' 273? If the engine can turn 7k+ you would need heads that flow at that rpm. Would a set of ported magnum heads work? I assume a 2.02 valve head doesn't fit on a 273 block?

A set of old school iron W2's would be a fun experiment if they fit.

Posted By: patrick

Re: New idea for a 273 stroker - 09/26/11 07:42 PM

anything larger than the stock 1.78/1.5's require notching of the bore for pbysical clearance

Posted By: scratchnfotraction

Re: New idea for a 273 stroker - 09/26/11 08:04 PM

so a ported set of #302 heads with stock size valves will work and be a closed chamber.

as far as bore notching goes on a 273, correct?

Posted By: dogdays

Re: New idea for a 273 stroker - 09/26/11 09:47 PM

The whole idea is to use a free block and cheap components to build a usable street motor. I've suggested Magnum heads in the past but they will require bore notching, which member Bigblockranger did in the car with a Dremel using coffee filters in the block to catch the chips. Hardly high tech!

Or home port a set of 302s.

If building a high rpm motor I would use expensive components and most likely build a much larger engine.

For this build it is max out the cubic inches, keep the rpm manageable and use a relatively cheap valvetrain.

R.

Posted By: RodStRace

Re: New idea for a 273 stroker - 09/26/11 10:28 PM

These flights of "What If" thinking are interesting, but I prefer building more common stuff.
I understand that a free motor sitting over in the corner can eat away at your gray matter, but add up all the parts and machining.
What percentage would a 175 dollar You-Pick-It 360 magnum be? On a 1750 build (CHEAP), it's 10 percent. If your dream engine is 330 cubes, you are getting 30 extra cubes, almost 10 percent for that extra 10 percent in cost. We won't even talk about roller cam, better breathing ports, and less valve shrouding.
The first issue with RPMs seems to be piston speed. The second is valvetrain issues. Try to find the circa 1979 Car Craft issues that had Dyno Don's P/S Arrow in them.

Posted By: dogdays

Re: New idea for a 273 stroker - 09/26/11 11:15 PM

If I wanted to be building or dreaming cookie-cutter engines I'd still be driving a Chevy 350. Where's the challenge in that?

If I had an extra $1750 lying around I'd be driving the "long-term stroker" in my '64Dog. I must not be in the "cheap" category, maybe mine is the "ultra-cheap". Paying for two households on one income with two kids in college will do that to you.

OF COURSE larger and better engines can be built, but where I live that 5.9 Magnum costs a minimum of $450 complete with 100K miles and a spun bearing or two. For $175 I can get a core 360 shortblock. So that free 318 block looks a lot better, because the stroker crank plus the free 318 are about the same cost as that $450 5.9.

The most important part, though, is the thrill of the chase. How can I do it better/faster/cheaper is what drives these flights of fancy. To me the alternative feels a lot like getting back to that 350 chevy.....

To each, his own taste!

R.

Posted By: RodStRace

Re: New idea for a 273 stroker - 09/26/11 11:37 PM

Cheap summit rebuild kits are $200
http://www.summitracing.com/search/Depar.../?Ns=Rank%7cAsc

Add in your dream pistons, rings, rods.
Don't forget doing something to the bores and the valves.
We won't touch on WP + coolant, OP + oil and filter, RTV, or other stuff you may already have.

I don't know where you live, so I don't know what's available local.

http://www.u-pull-it.com/
ENGINE- FUEL INJ (W/ACC.) 192.55 WO warr. 240.69 W warr.
cheaper if you pull off the EFI.

http://ecoparts.com/index.htm
half off sale Oct. 1

http://www.picknpull.com/part_pricing.aspx

The 360 could probably be hosed off, painted up and run fine. Scrounge up a carb intake and carb.

Posted By: jcc

Re: New idea for a 273 stroker - 09/27/11 02:33 AM

Quote:

so your exotic, expensive 330CID 273 based stroker has the same HP/tq potential essentially as a .060 over 318....or less than a stock stroke 360....

, thats GOT to leave mark.

Sorry to Op to be so blunt, but other then the glory of seeing their own post get a life of its own, I have yet to see over the years a "build to be different" post ever be admitted to by the OP as a build to be ****, no matter what logic is presented. I know its a free country and pretty free forum, but not sure what is really learned here in a post like this. And FWIW, I bought a car with a transplanted warmed over nice running 273, boy do I feel different.

Posted By: hunterstroble

Re: New idea for a 273 stroker - 09/27/11 07:33 AM

There is a guy at the track with a 11 second 273. His response is Never again! Lots of money in it, however it is so cool!