chevy 250 vs 292 inline six

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john1edwards
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chevy 250 vs 292 inline six

Post by john1edwards » Mon Dec 27, 2010 5:06 pm

Is there any reason why a 292 inline six wouldn,t make a better airboat engine than a 250 inline6. I think they are the same weight. at this point i mean direct drive. thank you for any input.
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Re: chevy 250 vs 292 inline six

Post by swampfox97 » Mon Dec 27, 2010 7:13 pm

People think that those engines have no performance parts available but U would be surprised what u can do with them

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Re: chevy 250 vs 292 inline six

Post by skinny99 » Mon Dec 27, 2010 7:23 pm

These folks make bada$$ stuff for I-6's. However by the time you upgrade one you could have a Small block that would make a lot more power.

http://www.cliffordperformance.net/Merc ... _Code=C250
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Re: chevy 250 vs 292 inline six

Post by JAMES » Mon Dec 27, 2010 7:23 pm

250: 3.875x3.53
292: 3.875x4.125
THATS THE DIFFERENCE...THEY ARE ALMOST THE SAME PREFORMANCE WISE. BEING DD ANY OF THE 2 WILL WORK ....
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Re: chevy 250 vs 292 inline six

Post by RLMelson » Mon Dec 27, 2010 8:11 pm

The 292 has more torque than a 250. My Dad had a 37 chevy coupe with a 292 bored .030 over with pop-up pistons. had the head milled some with V8 sized valves and a stout solid lifter cam from Clifford research. A set of headers with dual exhaust and a 600 cfm holley 4 barrel. this was backed with a 4 speed trans and a 9 inch ford rear end. He ran 3.70 gears in the rear. The coupe outran a lot of 8 cylinder cars. It had gobs of torque. A 292 would be a good DD motor. cam it up and put a gearbox on it. It probably would not equall a good built V8 but it'd be a good boat engine.
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Re: chevy 250 vs 292 inline six

Post by Olf Art » Mon Dec 27, 2010 9:54 pm

I was a kid back in the late 50's-early 60's, and I've seen a built 292 whip the pants off of some early V8's. Remember that the first Chevy 8 cyl. was only a 265, and the next one was a 283. The only thing you can't do with a big six is spin it too fast ..... the crankshaft is too long for that. It will begin to whip and take out the center main bearing, but on a DD boat you're not gonna be turnin' it much more than 3,000 rpm anyway, because of the prop, so go for it!

Also, keep in mind that a 292 with 4" pistons makes a 302. 8)
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Re: chevy 250 vs 292 inline six

Post by watersports7 » Tue Dec 28, 2010 9:28 am

the 292 has approximately 10 HP & 50 ft- lbs. of torque advantage over the 250
The 292 was only used in Chevrolet and GMC trucks; the block deck is taller, along with a relocated passenger-side engine mount. These were produced between 1962 to 1990; production of the engine shifted to Mexico after 1980. Year 1988 (only) 115 hp @ 3400 rpm and 215 lb. ft. @ 1600 rpm

The L22 was a 250-cubic-inch (4.1 L) I6 engine produced from 1967 to 1979. The '78 Camaro had 105 horsepower (78 kW) and 190 ft·lbf (260 N·m) of torque with the 250.
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Re: chevy 250 vs 292 inline six

Post by Olf Art » Tue Dec 28, 2010 11:50 am

Watersports, what year was it that the L22 went to a different head, with the intake manifold integrated into it .... '73? The aftermarket intake stuff won't work with that head design, right?
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Re: chevy 250 vs 292 inline six

Post by john1edwards » Tue Dec 28, 2010 6:59 pm

thanks for the information. if I go through with the project. I will post results.
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Re: chevy 250 vs 292 inline six

Post by watersports7 » Tue Dec 28, 2010 7:09 pm

The integral intake started in '75 They had a terrible scrap rate and were prone to cracking! The other disadvantage is they are so dang HEAVY
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Re: chevy 250 vs 292 inline six

Post by Duane Scarborough » Tue Dec 28, 2010 7:17 pm

John,

If nothing else, an inline 6 would be different from what most people are running.

It almost makes me sick to say it, but I bet that a FORD (yeah I said that nasty word) 300 inline six would make a decent airboat engine. They had a lot of low end torque.

But what I've never SEEN, was a Mopar Slant 6 engine on an airboat. Now THAT would be cool.

Let us know how it works out for 'ya.

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Re: chevy 250 vs 292 inline six

Post by Olf Art » Tue Dec 28, 2010 7:38 pm

Duane, those Ford 300 inline 6 cyls. are damn near bullet proof. They were run many millions of miles in the UPS delivery vans worldwide before that company went to diesel. The only problem with them is that they're HEAVY.

Like you, I do like different .... I'll give up a little performance for 'cool' anytime. I may be slower than the rest, but I'll be along shortly. 8)
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Re: chevy 250 vs 292 inline six

Post by Bdriller » Tue Dec 28, 2010 7:55 pm

in 1984 i didnt know any better so i built a 300 ford 6cyl. 260 comp cam, mallory dual point dist., aluminum 4 barrell intake,
holly 500 cfm vacum secondary,custom stainless headers,steel crank weighed 95lbs, thrust bearing in center of engine great place for it, engine weight right at 450lbs, spun a 70-30 woody wide blade 2900 rpm, same prop selected for our 350 chevy. spun up to 29 a little slower wind up than the 350.14x6 glass hull . i ran the boat hard for 6 yrs and sold it, built a bigger boat. looking back it was a great setup, never had a engine problem. I ran up on this boat a few months back it was still going strong , i asked the owner what all he had done to the engine over the yrs. he replied not one thing. I truly believe that is a great engine. the massive crank with center thrust has got to be a plus , i probably had more fun with that boat than any others. wait i forgot i broke a fan belt once.

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Re: chevy 250 vs 292 inline six

Post by Larry » Tue Dec 28, 2010 8:52 pm

My neighbor built a 300 ford on a 10x7 shallow hull and it spun a 66x38 right at 3100. Great running boat and a bullietproof motor, he always carried a spare duraspark module with him though from experience with his truck. Only reason he got rid of that boat was to get a dd caddy on a rivermaster because the family outgrew the boat.

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Re: chevy 250 vs 292 inline six

Post by Wild Bill » Wed Dec 29, 2010 1:44 am

I can't imagine any real benefit over a SBC or Caddy. Center thrust bearing has always been perceived as a weakness. Long crank can't help. I work on lots of inline 6 stuff and 300/6 Ford runs nicer than the Chevy's. I think the "Stovebolt" http://en.wikipedia.org/wiki/Chevrolet_ ... t-6_engine was built from 1929 to 1936. For a DD I would go, Stock Caddy, 400 SBC, 383 SBC or 350 SBC. Might consider a stock 454. Just the extra length of the block makes it perhaps tougher to get off the nose and I'm sure there is not much difference between a stock 350 and a 292 at 3200 RPM

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Re: chevy 250 vs 292 inline six

Post by john1edwards » Mon Mar 28, 2011 1:00 pm

Results from my 250 inline six with 58 inch six blade warp drive. 9 degrees 2500 rpm on trailor, 7 degrees 2650 on the trailor, took off two blades to make bow tie. 7 degrees 3000, 9 degrees 3000. on trailor. (will not run green grass in yard.) still expermenting -- soon may swich to 292-- will post results [warp drive does have more snap (instant power)than wood 66x34]
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Re: chevy 250 vs 292 inline six

Post by Olf Art » Mon Mar 28, 2011 1:26 pm

Good to hear back from you, John. What size hull did you say you had? Green grass is a tall order for any boat that doesn't have quite a bit of power ..... we already told you not to expect a hill burner, so hang in there.
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Re: chevy 250 vs 292 inline six

Post by john1edwards » Tue Mar 29, 2011 8:42 am

Its a 13.5 glass hulll. I traded this boat for my vw powered boat. its a project boat Ive been patching holes and replaceing some of the rigging to make me happy. I am not the slickest guy, I want something that is stable in deep water. Plus I think a bigger boat may go better because of more surface area. I took it to 3a south a couple of weeks ago. ran some sawgrass. ran nice. I need to put steel flex on the bottom or something. was told steel flex 2000 is slick and stays on good.
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Re: chevy 250 vs 292 inline six

Post by john1edwards » Tue Mar 29, 2011 8:57 am

http://www.youtube.com/watch?v=2UAXa8hz ... 4&index=11 Here is video on brown grass, when I first got boat. wood prop 66x34
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Re: chevy 250 vs 292 inline six

Post by watersports7 » Tue Mar 29, 2011 9:02 am

john1edwards wrote:Results from my 250 inline six with 58 inch six blade warp drive. 9 degrees 2500 rpm on trailor, 7 degrees 2650 on the trailor, took off two blades to make bow tie. 7 degrees 3000, 9 degrees 3000. on trailor. (will not run green grass in yard.) still expermenting -- soon may swich to 292-- will post results [warp drive does have more snap (instant power)than wood 66x34]
is the 58" warp a typo? (maybe 68")
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Re: chevy 250 vs 292 inline six

Post by john1edwards » Tue Mar 29, 2011 9:38 am

no 58 inches, someone cut this prop down. the price was right that why I got it. Also Larry said a 60 inch six blade warp drive worked good on his 250 inline six, but found out later he had modified engine to have more compression. (maybe when I put the 292 i will be able to turn all six blades in 2800 range.)
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Re: chevy 250 vs 292 inline six

Post by john1edwards » Tue Mar 29, 2011 9:41 am

If I can find some longer blades may consider going longer with less blades? any suggestions thoughts????
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Re: chevy 250 vs 292 inline six

Post by watersports7 » Tue Mar 29, 2011 9:51 am

would try a longer prop myself, cant help but think the short length is a limiting factor...
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Re: chevy 250 vs 292 inline six

Post by Olf Art » Tue Mar 29, 2011 1:16 pm

I agree. If you can find six longer blades go ahead and get 'em. You can run four for now, and if you pick up a 292 you might be able to run all six with a little less pitch.

I watched your video and think your boat runs just fine on the dry for a 250. Some good bottom coat will make it even better. Remember that you need to stay as light as possible, and that your engine makes max. torque at a lot lower rpm than most, so don't be afraid to load it up with the prop.

Nice little boat, man .....
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Re: chevy 250 vs 292 inline six

Post by john1edwards » Sat May 28, 2011 8:03 am

I put my wood prop on with tac to see rpms. The wood prop is a 66x34. on trailor 2575 (250 inline)
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