cort351w

You can take an engine, put in a crank from a smaller engine (265 in an LT1, ?? in LS1, 350 in 400rat) to make a destroked, rev-happy (providing that the internals can back it up) engine that sacrifices some torque to make a lot more power over a broader power band.

There was a post not long ago where someone was talking about the stroke/bore ratio being important. This makes sense if a 37? cid destroked 400 rat (I just don't want to mix this up with the 400sb) can rev to 7000 or more.

Also, check this out--post on camaroZ28.com about destroking 350.

http://web.camaross.com/bb/Forum13/HTML/004647.html


Can the same principle be applied to a 305? I realize that displacement would go down into high 200 range, but what do y'all think? I helps out the 350s/400s.

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91 formula WS6 305 tpi, T-5, 20,xxx actual miles, Cyclone headers, true dual exhaust, Moroso Blue Max wires

[This message has been edited by cort351w (edited November 14, 2001).]

iroc5speed

it would help revving, but why would you want to lose valuable cubes? I don't think it's worth it.

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'86 IROC 5-speed
305 LG4
edelbrock performer rpm intake
edelbrock 600 cfm carb
msd pro billet hei distributer
'95 3.23 rearend
hotchkis rear suspension
PST front polygraphite suspension
"speed kills. buy a f@&d, live forever."

cort351w

sorry, meant 400sb

I would lose the cubes for the reasons I stated. I have put this on some other post, as well, but Motor Trend just made a 302 out of an LS1. It put out 350 hp at the rear wheels compared to 280 hp at the rear wheels of a 2002 SS (stock LS1). The 280hp was obtained from dyno testing in an article in the same issue (dec. 2001).

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91 formula WS6 305 tpi, T-5, 20,xxx actual miles, Cyclone headers, true dual exhaust, Moroso Blue Max wires

Grim Reaper

When you destroke an engine, if you want to use the stock rods, you need to get different pistons. If you can find a match between the reduction in the stroke and the length of rod, it is possible to then use stock pistons. If you don't get the proper pistons to match with the rod/crank combo, the piston will not be at the proper position at TDF (too high or too low in the bore).

Using a 3" crank in place of the 3.48" crank would require rods that are 5.94" to allow you to use the stock pistons. If you use a 6" rod and stock pistons, the piston will be .060" too high in the bore (from stock position). With the stock block deck height of 9.025", the piston will exceed the deck height by .035".

The other alternative is to get different pistons. The problem is that 305s are not very common and what parts there are, is more expensive than a 350. If you REALLY are hell bent to do this, it HAS been done on a 350 and there is a wide range of parts available.

Build a 302 (4" bore 3" stroke) or a 306 (4.03" 3" stroke). Then you are keeping your much badly needed cubic inches while having your revver. There is a combo where you use the 3.1" crank from a 262 V8 with a 4.030" to make a 316. I don't know if there are any good forged versions other than the stock.

But I have one silly question, why do you want such a high revving monster? Generally they are too radical for the street (read "not fun" to put in traffic), but are a dandy race motor.

Personally, most of my driving is street (though I like my power too). The combo I like is the 415 Motown Shortblock. Just adds head, cam, intake and accessories. This combo will give you a ton of torque and you won't have to rev the snot out of it to make the power. It is more expensive to make a combo that can see 7,000 rpm, hold together and LAST!

This is another reason those high strung engines are so great for racing, generally, you rebuild them fairly regularly - you don't care if it lasts less than 50,000 miles. But if you want a motor that will last and get LOTS of mile - you are heading on the wrong path.

Just make sure you are clear on what your intended usage will be and make a motor to match. You'll be much happier.

Beast5spdGTA

Another thing I think you are missing is your comparison I'm sure is wrong. I didn't read the article so feel free to call me out if I'm wrong, but I'm sure that 302 LS1 had the help of headers, non-stock cam, and probably compression and/or ported heads. If you do that to a 346 LS1 you easily get 500+ flywheel hp and 400+RWHP. So the stock size LS1 kicks the little LS1's *** .

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14.62@96mph headers, muffler, chip, ghetto stuff, duct tape
89 GTA 305 TPI 5 speed 3.42 gears

82camaro

Destroking doesn't add power. More rpm is required to make the same power. With the same parts(you can't compare a modded 302 LS1 with a stocker), a 350 will make more power than 'destroked' 302 throughout the powerband. If your worried about it staying together at high rpms, try longer rods and high quality internals. I've seen 400/350's last a full season of circle track without ever being taken apart(8000rpm at the end of the straight). Stroke is increased to create power, look at the 383.

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350 with stealth intake, holley carb, 470 lift cam. 700r4 with .5 boost valve, vette servo, tci lock-up kit, B&M megashifter. Richmond 3.73 gears, powertrax locker, timkin bearings, synthetic lube. Custom 3 inch single into 2 2.5 pipes. 1 1/2 drop springs, 1 5/16 solid front sway bar, 1 inch rear bar, custom subframe connectors, custom LCA relocation brackets. Kobel ground FX, currant red metallic paint. Lots of other stuff...
82camaro

AJ_92RS

Super Chevy did an article in the Jan 2002 issue about different build-ups that you can do just to be different. It's all about de-stroked engines.

They have a "build up" of a 305 that can be used. They're all theoretical build ups so they have no power results.

They have either a 267 (not the same 78-81 engine ) or a 276.

For the 267 you would need the crank out of a 4.3L (265cid) V-8 that they used in the Caprices in 1994. (3" stroke).

For the 276 you would need one out of a 1975-76, 262 cid (3.1" stroke)

They calculated the comp. height by using a 5.7" rod and a 0.010" deck clearance.

The 265 crank (3" stroke) would be 1.815 CH
The 262 crank (3.1" stroke) is 1.765 CH

These engine sizes were also calculated by using a .030" overbore.

It seems like it would be do-able.

AJ

cort351w

Um, yeah... I'm not sure why I didn't see this when I read the article the first time, but you are EXACTLY right.

Here is exactly what they did:
"Westech Automotive removed the stock LS1 and stripped it down to a bare block. Afterward, GM crankshaft, lightweight rods, and 11.5:1 pistons were installed. Up top, a set of highly modified Corvette LS6 cylinder heads, shaft-mounted roller rocker arms, an aggressive solid roller-lifter camshaft, and a Z06 intake manifold were added. TTS Power Systems supplied custom headers with 3.0-in. exhaust and performed special computer calibration. Chassis dyno testing revealed a stout 378 rear wheel horsepower at 6800 rpm." They go on to talk about the 18" torque thrust II's, Hotchkiss suspension, brakes, interior, and rollbar.

Yep, you're right, that amount of money could make a stock LS1 go much faster.

I was just wondering if there was hope for my little 305 down the dimly lit De-stroke Avenue.

Thanks for telling me what was in my own magazine article that I supposedly read

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91 formula WS6 305 tpi, T-5, 20,xxx actual miles, Cyclone headers, true dual exhaust, Moroso Blue Max wires

zippy

to destroke the 305 you'd want a L99 crank and rods using 305 pistons. the rods are available through gm performance parts and the crank is available all over for the L99. this also works on the 350 to destroke it to a 302. for the 350 you'd just use the L99 crank and rods with 350 pistons.

rmmstnr

Nifty! I've been looking for what rotating combo to use for my planned 263. This sounds nice and simple.