How much power can you put through a stock 2bolt block before it starts distorting or breaking ?

 

I got 550HP and 510Tq (dyno verified numbers) out of my 406ci and as far as I know the engine is still running in another C3 after 10 years plus. I did put ARP main studs in it.

 

Normal belief is around 550 hp. with a forged crank / hardened

 

DO you remember what cam you were running in that motor? thanks

 

A 406 isn't a stroker, it's just a .030 over 400. That said, the 2 bolt blocks are normally stronger than the 4 bolt blocks. At a minimum use a good main stud kit. Ideally you would have 4 bolt splayed caps installed.

When the blocks break, they crack from the front main journal up into the camshaft journal.

 

If you havent built it sell the block and buy a Dart..then stroke itnow youre talkin!

GM 400s are crapshoots too risky.

Why risk thousands in parts and machining just to have one crack from torquing the heads down (yes it happens) not worth it

 

Comp Cams Solid roller XR276R

 

I have a GM "509" 406, two bolt block in my camaro. 10.03:1 compression, Dart Iron Eagle heads (200cc intake 54cc combustion); comp cams XR282HR (hydraulic roller), Speed pro Hyper pistons and stock 400 crankshaft.

Desktop dyno (did not run in a shop dyno) says it should be about 450-460HP and 500-515 ft/lbs...again, I cannot say if those are the reu numbers, but runs like a beast, and stays nice and cool...

GM blocks are fine--just have them magged and checked by a machine shop. If you want to go "extreme," then yes, an aftermarket block is a good idea--but you can get plenty of power out of a GM block without worry...

 

i got 560 hp but at my request Richie drop it to 520 hp on dyno .7 pulls till i was happy. 4 bolt with arp stud kit in strongest block. block must be casted prior to oct/nov 1972 TO. block . the block is also the heaviest sbc made.they reduced the block weight of the 400" after that date in both two and four bolt main for pu truck and caprice sw. thus the rep.for weaker 4 bolt comes from the lighten block (in the day GM. was going every which way to meet new EPA. standards.)without turbo/supercharger/juice it will last years with proper build.laying the eary block and later block on ground with bore down you can easily see were they removed metal casting from web area under the main bolt position.

 

factory used 5.5in rods, so what is it then when a 5.7in or 6.0in is used?

A friend has one that has a forged bottom and is making metal in the oil, tear down shows out of round cylinders in the low load area. No cross hatch in cylinders and should only have about 10k miles on it. Thought to make 500-550hp no actual numbers. Does this sound possible?

 

The rod length has nothing to do with a motor being "stroked." It is the actual stroke length of the crank that matters...the length of the rod should be matched ot the piston that you are using...

The stroke on a 400 is 3.75", and can be achieved with varied rod lengths...

400's often recommend a longer rod than stock, because it does relieve some stress on the pistons/cylinder walls, which can free up horsepower in a performance build...but again, a longer rod does not mean the motor is "stroked."

 

[QUOTE=keithl1967;1592269290]The rod length has nothing to do with a motor being "stroked." It is the actual stroke length of the crank that matters...the length of the rod should be matched ot the piston that you are using...

The stroke on a 400 is 3.75", and can be achieved with varied rod lengths...

400's often recommend a longer rod than stock, because it does relieve some stress on the pistons/cylinder walls, which can free up horsepower in a performance build...but again, a longer rod does not mean the motor is "stroked."[/QUOT

 

when building a 400"sbc you must use 6" rods or don`t bother building at all.these are the words of the world champ. a total explanation was given to me but without the technical talk it is all about the amount of time the rod spends at TDC . of course you must also keep in mind those short rods OEM. (5.56)" are also trying to go out the side of block! 5.7" rods helps but the real deal is the 6" rod and torque advantage. think DIESEL bore /stroke and rod size.-------torque!

 

I do not see that cam listed on their website? I see a hydraulic roller with that part number?

 

Sorry XR274R

 

skip white

Item No: 406_STG_3
CHEVY TURN KEY SBC 406 SUPER STROKER STAGE 3.0 CRATE MOTOR DART BLOCK 565hp

Price: $6,985.00

SBC CHEVY TURN KEY STAGE 3.0 HYDAULIC ROLLER CAM 406 SUPER STROKER ENGINE 565HP PRO STREET SETUP. RUNS ON PREMIUM PUMP GAS. FORGED PISTONS, 6.0" SCAT COMPETITION RODS, NKB-200 ALUMINUM HEADS. BUILT WITH A DART HIGH PERFORMANCE RACING BLOCK. 100% BRAND NEW.

as info internals


introducing our Turn Key fully dressed Stage 3.0 Roller cam 406 Super Stroker 565 hp engine. The build sheet is at the lower part of this listing. 100% brand new. Built with a Dart high performance block. The term, "Super Stroker" is in reference to the rotating assembly used in this engine. Unlike some our other engines, this engine uses a 6 inch rod, versus the common 5.7, SRS racing pistons, versus the FPS street/strip pistons, and a 1/16 ring pack versus the thicker low cost 5/64 ring pack. These three upgrades are very valuable when it comes to performance. No drawbacks whatsoever to any of these features other than an increase in cost. These features create a much greater efficiency in the engine. The best feature about the 406 is the wide bore diameter as compared to the 383. This creates a great amount of torque in the lower rpm band. The brand new Dart racing block has very thick cylinder walls, and easily accomadates the wide bore pistons. This engine is also offered with a true duel pumper Quick Fuel carb when selecting the larger cam.

This engine is designed for street/strip use. Premium pump gas friendly.

THE ENGINE IS COMPLETE FROM CARBURETOR TO OIL PAN.

 

Still not a stroker, i don't care if puke white says so. Any engine that has a crank shaft with more stroke than factory is a stroker, 383" is a stroker, 400" not. Now then the dart Block is probably a sph 400 block and if white bored it to reach 406" then they wasted a rebuild as 6" worth of bore might show up as 1 tenth on the strip, stroker is a buzz word for parts dealers.

 

So youre tryin to call him Earl Schieb of motors or somethin'?

 

There are plenty of 5.700 rod 406's running around......it makes zero difference on the street.
Do not be afraid to use a 4 bolt 400 block either at street power levels....the 2 bolt is stronger in the main webs but only stronger overall if splayed caps are applied.
If you happen upon a nice 400 block.....by all means use it...
Put at least a 200cc head on it.....and do not be afraid to use a single plane manifold either. I chose Dart and Weiand Team G respectively.
Cam choices vary wildly....but I decided on a Comp 292h Magnum w/1.6 rocker for 244/244@.050 and .538/.538 lift with the rockers....
With a single plane intake and a worked 750hp, better than average exhaust it will throw 420 to the tires all day long......

Jebby

 

HP is a calculation, engineering wise you can not rate parts with it. Compression ratio and piston speed would be the determining factors in what the stock block will take.

If you are staying around 10 to 1 and 3.75 stroke you fine. You put 14 to 1 on it and 4" stroke then you have a WILLPOP.....will pop at anytime.