What benefit would there be to building a 302 over a 350 or a 327 over a 350? Revs? I have a stash of parts and am wondering what to do with them.
If you're wondering what to do with your "stash" of parts, SEND THEM TO ME! I'll add em' to my stash of parts and maybe be able to put something together. Other than that, THERE'S NO SUBS***UTE FOR CUBIC INCHES. And, 350's are a lot cheaper to build. A 302 will need a manual trans, low rear end gears, and a lot of maintenence (sp). And check the availability and price of those pistons. A nostalgia 327 would be nice and not a belly ****on 350, just costs a little more. BUTCH.
here is a quick ***umtion on these three....lets say you want to build something mild say 1hp per cubic inch: 302 = 302hp 327 = 327hp 350 = 350hp now lets get radical and build 1.5hp per cubic inch: 302 = 453hp 327 = 490hp 350 = 525hp keep in mind that the torque increase is also much better as you get longer in stroke.....but I'm a HUGE fan of rpm's, so if you decide to go with a 350 let me know...I'd love some more 302 stuff!!! Nothin sweeter than bangin gears above 7000rpm!!!!
The easy answer is that anyone who runs a 302 is a ruler. I like the smaller displacement motors, but that's just me. I like manual transmissions, and I like to turn more RPM than a mild 350 is happy with.
I have had the thought that IF I was going to build a SBC the 302 would be cool just for the sake of being different. Enginemasters I think did areally cool one a year or two ago, built for high rpm with modern iron heads (i think). It's a neat engine.
I've always prefered a high rever in a small light weight car, so I guess it would matter what kind of car you were putting it in, and what you plan on doing with it.
The phrase is "volumetric effeciency". Larger engines will surp*** their volumetric efficiency limits at a lower RPM than a smaller engine. Remember that the small block Chevy was originally a 265 c.i. engine, then increased to 283, 327, 350 and 400. There were also a few variations like the 302 (to meet Trans Am rules on C.I.), 307, 267 (? smog ?) and 305. I'm no expert, but it seems to me that in a lot of cases the engines were upped in size or HP because that's what "marketing" wanted. In the sales wars, Chevy didn't want to be pushing a 327 if the compe***ion had something bigger. I think the 327 was a very good balance of size and performance vs. economy and "driveability". I'd guess that the 350 wasn't really much of an improvement except on paper. The 302 is a high revving engine, best suited to racing and high rpm applications, better have the right cam and good intake and exhaust manifolds. 307's can be made to run similar, but 305's are totally different in that they are just an underbored 350. The 327 and 350 are really the mainstay of streetable performance. The 400 has brute torque...great for truck/trailering, but it is almost useless at racing RPMs. It takes a lot of modifications to make a race engine from a 400. Anything above 350 really is starting to stretch the limitations of the small block manifold and cylinder head design. Again...the volumemetric efficiency goes out the window. A given carburetor will only flow so much CFM. A big displacement engine will have big demands at higher RPMs. If the cylinders are not filling completely, the compression of the engine drops off resulting in a loss of power at high RPM.
i've always wanted to build a 302, shure there is no replacement for displacement, but if you built 2 identical engines and 1 had peak power at 5000rpm, and the other made peak power at 7000rpm, the high rpm one would make the most power. look at dragsters, they are all set to run in the high rpm for a reason, thats where you make the most power. here is a link about the camaro 302: http://www.holisticpage.com/camaro/camaros/302.htm
OK, more seriously...and why i'm putting a 327 in my ride: The 327 was only in production for eight years, but in that time the engine would become a legend a**** small-block aficionados. What made the 327 so efficient was its large (for a small-block), 4-inch bore that readily accepted big-valve heads, combined with the relatively short 3.25-inch stroke. With standard small-block 5.7-inch rods, the combo yielded a 1.75:1 rod/stroke ratio, very close to the 1.80-1.85:1 ratio considered by many professional engine builders as optimum for an acceleration engine. Unlike with the later, longer-stroke small-blocks, installing longer aftermarket rods does not severely compromise piston design. In terms of cylinder feeding versus displacement, the 327-inch engine size seemed to dovetail perfectly with available cylinder-head port volumes and camshaft designs. For all these reasons, many believe that, with the possible exception of the even rarer '67-'69 Z/28 302, the 327 has the most horsepower-per- cubic-inch potential of any small-block. That's important if you're racing in a cl*** based on pounds per cubic inch; otherwise, raw inches are still king. And good luck finding a rebuildable core that'll clean up at 0.030-inch over. CC
You going to give me one? I'm trying to work with the parts at hand. Cam, heads and pistons will be purchased. I have at least three 4" bore blocks. A 4.125" block A DZ-302 crank A 327 crank 2-3 350 cranks A 400 crank. More 5.7 rods than anyone needs. A brand new set of 6.25 H-beams begging to go fast. I have a field full of projects from S-10's to roadsters. I was thinking 302 with an M22 for my Volvo 544. Picture a 50 year old Swede spanking a late model Ricer. Does the 302 offer ANY advantage over a 406? I can see where a lot of small displacement engines are built because that's what the rules of a given cl*** call for. There is a request on the board right now for a 305 recipe because that is what the rules demand. Just trying to stir up our collective grey matter to see what's out there. I knew this stuff cold 25 years ago....I'm doing good to remember my name and phone number lately. Hopefully somebody else learns something from this as well.
Maybe, sell the DZ crank for the mega dollars they get on Ebay to finance a high winding, big bore 377? The best of both worlds?
Oh...a VOLVO. With a manual trans. Yeah, build a 302. Look at it this way..you may make 500 pounds of torque with a ~400 inch motor. But unless you spend 10K on heads, great pistons, a ton of crank work etc, you're gonna shift it at 5000 RPM. Plus you'll never get enough tire under it to harness said monster torque without running a 2.70 rear gear. Plus side is it'll cruise 90 mph at 1700 RPM. If you build a 302, you can use a pretty much stock crank, a set of $500 pistons, and make an EASY 400 HP (depending on cam/manifold/carb/headers)with even stockish "camel hump" heads. You'll have 300 pounds or so of torque, which is plenty for a 544, and run a reasonable 3.90ish gear. And you can zing it to 7 grand without a care in the world, which is handy when one is faced with a stoplight warrior in a Honda.
See, this is what I'm wondering. I have a 4.125" bore block and a 4" bore block, a 3.25 crank and a set of 6.25 rods. So which is more efficient.. long rod 327 or over square, long rod 350? watch the question evolve as the thread grows. Thanks for the input so far.
That's a complicated *** question. It's actually two questions...rod length, and bore/stroke ratio. In general, the longer the rod the better (see ladies??) A piston on a long rod spends more time at TDC and less time at BDC. With a given head/manifold, a longer rod will usually make slightly more power (that's mostly due to the pistons speed, and the resulting effect on suction of the intake charge.) The difference in bore/stroke ratios between a 327 and a 350 with a huge overbore are about nil, with a slight nod to the 327. When you back up to your 302, you pick up a ton more oversquare, obviously, which tends to work better at higher RPM.
Stevie G, Now you're talking. Big bore, short stroke, Long rods and lotsa compression. Slap a good set of head on and you've got a screamer. You'll need bearing spacers to put the smaller main crank in the 400 block, either fedral or clevite seel them. A good balance job and to keep it smooth at big R's and life will be good. HRM did and artical back a few years on this combo, I'll try to find it and post it.
Stevie...you want to really be different? Put your 302 crank in the 400 block!!! punch it .030 over and use the 6.25 rods with a set of custom made pistons...I got mine from Ross and a set from Venolia...it makes 326 cubic inches and just beggs to be wound...my best one made 468lb-ft of torque at4800rpm and 686hp@8200 rpm....it had a solid flat tappet...Brodix #8RR heads, Holley Strip Dominator and a wokred over 850cfm dbl pumper. I ran it for 2 seasons in a prostock dirttrack racecar. I have the mild version of it still in my barn waiting to go in my vette when I finally decide to trash the TPI setup and go fast!!! Just another thought for you to ponder!!! Have fun man!!
The piston spends more time near both TDC and BDC. As the crank turns past TDC/BDC the long rod motor will show less piston movement per a given number of degrees on either side of these positions. The more time spent at or near TDC on the combustion stroke the less prone to Detonation caused by high compression ratios and low octane fuel, therefore with a rod to stroke ratio closer to 2:1 you can run compression ratios near 11.5:1 with good heads and not fear the detonation monster.
Almost, but no. A long rod motor accelerates a piston away from BDC more rapidly. I can prove it if ya want Getting too far off topic onto rod ratio, but that's one of the only advantages a short rod has. Since the piston comes away from BDC slower, intake vacuum rises sooner. That make a short rod motor a touch less sensetive to overcamming.
I was wondering if that had been done. Very tempting. I built a 400block/327 crank combo before but sold it before I had a chance to run it. This is all great stuff guys. The gears in my head are turning and I hope the rest of you got something out of this.
Go with the 327! It's true there is no replacement for displacement, but you can get damn good power out of a high-revving 327 and it's not a 350...Which is run by 90% of the hot rod world.....
it would be just asa easy to build a 400 ......as they are more readily avalible....406 would make a ton of torque ...and hp.....a customers 406 made 496 hp and about the same in torque ....with flattops ...6" rods ...a mild crane solid...and a pair of edelbrock performer rpm 180 cc heads...switch to a roller.....and a bigger head.....this thing would make 550 or more hp easily....for not much more money.... guess i will have to figure a head to use on my 301 shortblock.....all this talk of rpms.......lol brandon
Seems to me that the geometry at BDC is a mirror image of the geometry at TDC. Acceleration away from BDC would be exactly the same as acceleration away from TDC. When the piston "comes away from BDC," no matter how fast or slow, it's moving upward in the cylinder on either compression or exhaust. Vacuum is a factor when moving away from TDC and downward toward BDC on the intake stroke. I'm not trying to stir sh*t or start an argument. I'm always willing to learn something, so I'd be interested in seeing your proof if you don't mind. Thanks.
Pour whatever beer you like into a generic mug and nobody will be able to tell the difference. 265 or 400 or anything in between. All anyone is gonna see is a small block Chevy...so fill the block with what ya got and tell 'em whatever you wish!
Think I already answered this. But.............I'd build a small journal 327. Best all around compromise for a hot rod.
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