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small displacement V8


Guest Anonymous

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Originally posted by scott_d:

...the main reason I did not go this way is that i am poor and it coast about double what it does the build a standard small block.

 

just my thoughts.

My thoughts exactly. ALOT of cash for the same power, and you have to rev it a good bit higher to get the torque.
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Want to comment on an earlier remark about the red line of an inline 6 and same displacement V8. The in line 6 has a much longer crank. Thus the idea that a 6 will have a higher red line, "all else being equal", doesn't hold up. A 240 motor has a nice red line in part because of the short stroke. In agreement with what was said above.

 

My 2 cents.

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Hey Pete, that sounds like a wicked build your going with. I have to say I have seen a 283 powered Z around Dallas a couple of years ago and that car was not 15 second material more like low 12's, high 11's.

 

I do like the Idea of 283 twin turbo..Vroom!

 

Mike

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Guest Carlissimo

Its true that bigger displacement engines make faster dragsters. Everyone has their own preference. My preference has been to keep the "sports car" character of the original Z and to go for higher RPMs. The best times I have had with my car have been racing around on mountain roads..lots of curves, lots of accelerating and shifting.

 

I drove a 1968 302 Z-28 one time. It was awesome ! I think that motor is a close to a Ferrari engine as you can get on on this side of the Atlantic. It will run 8000 RPM all day. This is because of the short stroke.

 

If I had to do it all over again, I would build a 302 instead of my 327. Maybe not the best drag racer, but definately a great road racer.

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Thanks (If that's in order) RPMS -

 

I too am recalling a drive in an early Z28. A proper sports car engine for sure.

 

All this talk makes me want to start collecting SBC parts for a 4" bore, 3" stroke motor.

 

There are two substitutes for cubic inches: boost and/or high RPM. My creation will have both.

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Guest Anonymous

There was a large journal 302 SBC crank on E Bay. My old pal had a 302 Z 28 and often offered to let me drive.I was afraid of it because around 80 mph you were so pinned to the back of the seat it was difficult to move.

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Guest Anonymous

Quick question. I ran the casting number on my block and it came up as either a 302 or a 350. Anybody know how to tell the difference? It seems like it revs pretty high, but my tach doesn't work so I'm not sure. I'm probably selling the car, but if it were a 302 by some chance, I'd probably reconsider.

 

Thanks for your help.

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I have been lurking on this post for awhile and thought I would weigh in. (Sorry...)I like the idea of a "little" v8 and think the baby LT1 (4.6 litre) would be an ideal swap for a daily driver. All of the looks and drivability of its big brother but at a significantly reduced price and MUCH easier on a T5. But this is for a fun daily driver. Now, if max output is your goal, displacement is the name of the game to a point. The 302 has a very high "cool factor", but since you have to pony up big bucks for a crank and pistons, why not go bigger? You can make a 355 rev as fast as a 302 if you can keep the reciprocating weight down and flow enough air. Just run a proportionately larger camshaft and larger cylinder heads with a lightweight recip assembly. The 302 was built to fit the 5.0 rule for Trans Am racing which by its very nature keeps the engines at very high rpm for extended periods of time. This is not a problem on a street car, so a high rpm longer stroke motor should have fine longevity since it just doesn't remain at bearing damaging speeds for long. At some point there is a law of diminishing returns to both displacement and cylinder bore. Thus it is MO that THE best choice for a max effort car is this: Big bore, short stroke, max displacment. Not a contradiction! 4.125-4.155" bore 400 block with a 3.25" stroke crank. This takes advantage of the larger piston surface area of a 400 which increases cylinder pressure and unshrouds the valves. It also uses the smaller crank bearing diameter for reduced crank bearing speeds while the short stroke will reduce piston speed compared to a 355. Coupled with a mechanical camshaft (flat tappet or roller in the 260 deg duration at .050 and .550 lift to make life easier on springs on the street)This should net about 360ci and a 7500 rpm power range for well over 500hp. It could also be coupled with a 3.5" stroke crank to build a 380ci motor. As usual, the bottom line is the almighty dollar! I would build a 302 with 11:1 pistons (stock replacemts) using a small journal 327 block and a 283 crank, but for the street might as well build the 327. All things being equal, a 365hp 327 could put it on a 302, even an L79 350hp 327. 400 and 383 have become popular because they are cheap, something to consider but I am not a fan of the 3.75 inch stroke, (although internally balancing tempers that) but that is just personal as they run quite well. I still think a 355 short block coupled with the best heads you can buy is the way to go for a BUDGET max effort street motor. FWIW, the 358 ci Nascar motors make 700+hp at 8000 rpm. They also run between 7000 and 9000 rpm continuously for 500 miles at a time! They use the 4.125" block and as they overbore to repair, they manipulate the stroke to remain in the 358ci range. My neighbor owned the "World's fastest SBC powered Corvette" for a couple of years. It had a Nickens Brothers 388 cubic inch motor that made ~950hp with a single 4 barrel carb at around 9000 rpm. The backhalfed 66 'vette had a 7000 rpm converter (!)and ran 8.37 at 160+ on the ProGas 8.90 index :eek: . Obviously piston speed and longterm durability not as important in a motor that is gone through at LEAST once a year, but shows that you can get that high rpm action from larger displacements.

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Guest Anonymous

Nick. Engine block identification for the SBC 302 is: 3914678 and 3956618 .The problem is that 327 and 350 SBC's of 1968-69 shared the same identification #s

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Guest Carlissimo

Saying there is no difference between a short and a long stroke motor is like saying there is no difference between a Viper and a Corvette... or between a Harley and a R-1.. or between NASCAR and F-1. They are all fast in their own way, but they are all significantly different.

 

Bottom line is that there is a lot of fun and enjoyment in a high powered Z-car, no matter which course you choose.

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Guest Anonymous

Some like em tight some like em loose some like em wet some like em dry some like em smokin some like to long stroke and some like to short stroke sum like to vary stroke and then there is some thet don't like ema at all. But for the long haul big,well lubricted made to long stroke.A 302 maybe fun for awhile before it wears out but a 383 has staying power

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