As I'm mulling over my long term drivetrain options for my IROC, I've been exposed to the suggestion of a 'stroker motor'. I believe that this has to do with a taller rod and high pinned piston? What is the basic benifits of a 'stroker'.
Are the 335 and 383's all considered 'strokers'?
Nitro

 

a stroker motor is basically taking a crank from one engine and sticking it into another a different engine, such as the popular 400 crank in a 350 block makes a 383, you can also destroke some engines to make them spin alot higher and make good topend power.

 

to elaborate on travis's statement

a stroker is when you lengthen the stroke on a motor. You don't exactly have to take another stock crank size, ie 400cid crank in 350 motor, you can use a custom length stroke crank, like a 3.85"" stroke in a 350 motor or something.

Longer stroke is more cubes is more power. Nothing magic, you're just getting more cubes from a smaller block. If you can get a 350 block, and 383 crank (a 400CID stroke length, but journal size is for a 350 block) for cheaper than a 400cid motor, then go for it. But if you can get the whole 400CID block for roughly the same price, go for that. Another 17cubes is more power.

 

i never thought a 400 block was a sbc, or it isnt? if it is, is it the same size externaly as all the 350 sbc?

 

A 400 is a smallblock. same thing on the outside just like any smallblock!

 

ford also makes a 400cid motor, but who cares about what ford does?

 

the dreaded f word

 

There was also a "396" Big block displacing 402 cubic inches, so that's probably where you're getting mixed up.

 

yep the big block thing was always confusing to me too. There certainly are both small and big 400 blocks. I believe it has to do with the amount of wall space between cylinders??? Hard to remember that one....
Nitro (and thanks for setting me straight on the stroker)

Oh, if I was to fit a 400 block crank in my L98, would I have to change anything else (emphasis on 'Have To')...

 

as myself have recently done the stroker mod, there is lots that 'has' to be done, not in all occasions, but in most, you need to grind the block to clear the stroke of the counterweights of the crankshaft, also you need to make sure the rods will clear the camshaft now since they do come up higher. if so, you may need a small base circle cam ground. also, specific pistons so as to not be pounding them into the bottom of the cylinder chamber. oh and on the stock oil pan, i had to massage it quite a bit to clear the stroke of the counterweights as well. thats about it as far as 'have to'

 

yup it is a small block. same size block on the outside main difference is the cylinder walls where made from the factory with a 4.125 inch bore rather then the stock 4.000 inch bore. took some redesigning to do though but it works.

 

is that a gorrilla small block 3 differant engines combined 350/500 hp

 

Aren't the cylinder walls in these motors dangerously thin? I've always heard there was a strong downside to 400 blocks, which is why they aren't all that popular.

 

They're quite thin, you're correct. However many people run them without problems. I know a guy personally (he's on these boards as well) with one in a third making around 600 hp.

 

one thing to remember. and this isnt a shot at strokers at all, is that you will have greater piston side loading and piston speeds increase causing more stress and wear. There is also more time at TDC and BDC where the piston isn't moving at all.

I used to be in love with strokers but a few talks with a few drag racers and that changed my mind

 

Why exactly is more time at TDC and BDC bad? Also, what is else 'wrong' with stroker motors?

Besides the stress, I have always tbought strokers were better. More cubes and more torque.

 

biggest problem I have heard about is cooling issues at times. but I don't know off hand.

I also know though they have a 427 SBC as well

 

Scarcity makes the 400 relatively unpopular, not cylinder wall thickness. The thrust wall thicknesses on a 400 block aren't much different from any other small block of the same period.

GM never made a 427 small block, that's an aftermarket creation.

 

Yea, theirs some pretty neat creations out there now. SB 415/427/454

454 smallblocks pushin 600hp out of the crate!

 

Those are typically built on aftermarket blocks as well. You'd be hard pressed to make a stock 400 block make 600 HP for any length of time. Some of the larger displacements use a 4.25" bore as well, which is impossible on a stock block.

 

From what I recall the 400 small block 400 big block all started in '70 with the impalas. The 396 was up in size starting that year and in the chevelles it retained the 396 badging but the impalas were badged 400. So in all actuallity a 400 big block in terms of chevy was actually a 402. Carry on.

 

It started in '67 actually... the 396 was bored out .030" more at the factory giving it a 402ci actual displacement.

They kept calling them '396' because of the great performance reputation they got almost immediately after release in 1965, so they just kept it going. There hasn't been a 'real 396' built since 1966.

 

the 427 though can be made usign the stock block with some boring correct?
at least that I think is what I have heard with the gen I and II blocks and while I have heard of smoe 427 gen III blocks I'm not sure how they do that one.

 

A small block 427 is built from an unbored 400 block with a 4" stroke. Boring the block by .030" makes it a 434.

 

one more rather important little detail, is to cut down the main bearings to a 350 size. The 400CID block used larger main bearings. Better option is to buy an aftermarket "383" crank, where the mains are already the right size. After you take an old 400CID crank, turn down the mains, and polish/turn down the rod bearings you may as well have just bought a new crank for the cash outlay. Capscrew rods help with the cam clearance issue as well.

 

Yes, the rods, or the pistons, or both.

 

per musclecarclub.com "Under the hood, the proposed new 454 blocks never made it and the Camaro SS continued with the 350 and 396 engines. After January 1970, however, the 396 engines no longer displaced 396 cubic inches. Chevrolet actually enlarged them to 402 cubic inches but the executives decided to name it the 396 to take advantage of the name recognition and avoid any attention from insurance carriers."

 

The new LS-7 is a SBC 427, but it is also a pretty marvelous piece of technology too.
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They spend more time not moving at TDC and BDC as the longer stroke passes to "the otherside" of the block. This is bad because it causes a dead signal to the carb or really more over lowers RPM potential. Besides your not making power unless the piston is moving right?

 

when a piston spend more time at TDC/BDC then another motor it will actually have a slightly higher peak piston speed. once that piston starts to move again it will start to pick up speed a lot quicker. read up on long rod vs short rods inside engines and you might see waht I am refering to.

that higher piston speed creates a better vacuum signal to the carb.

with the time dwellign at TDC and BDC had some other effects that where not all that undesirable but I don't remember them off hand.

eitherway the effects should be small compared to what you get just by adding the cubes and making more power off that alone.

also if nothing else having more cubes is going to create a stronger vacuum signal then being at just 350cubic inches.

 

you know what. i believe you are correct.... hmmph i have the info from my Tech school course books somewhere im just too lazy to find it.

 

don't feel bad I'm too lazy to find otu the "other things that happen" as with the long dwell vs short dwell on a piston as well.

soon enough though I guess

 

the 400 sbc was relatively unpopular because of its shorter rod used to fit the longer stroke of the crank. a lot of people believe there are cooling problems due to the siamesed cylinder design, which has been proved to be a myth many times..it all comes down to the builder..

as for the dwelling at tdc and bdc longer, read smokey yunicks book "power secrets" he explains this very well...in short a shorter rod will be slower at BDC and faster at TDC and a longer rod will be faster at BDC and slower at TDC. what happens when you are slower at TDC? the piston will "dwell" longer creating more cylinder pressure and when you have detonation it will create a bigger bang...in short more power.

personally i dont like the idea of a 400 because of the shorter rod which requires strong wrist pins, piston pin bosses, and connecting rods than a longer rod. a longer rod will help peak power but may require exhaust porting to compensate for its spending less time from 90-o ATDC to BDC (which allows less time for the exhaust to escape on power stroke) and will force more exhaust out from BDC to 90-o BTDC. the short rod also exerts more force to the crank pin at any angle and creates more sideload on the cylinder walls..in short; longer rod= higher rod/stroke ratio (which should be your goal)

i really dont want to spend a lot of time going into details so i just highly recommend picking this book up from Amazon or the such...best $20 i ever spent. not recommended for you if you dont know whats going on inside that big metal thing under your hood cuz it will just confuse the **** outta u.

personally i thnk the ideal motor is a 350 destroked to a 327 with a 6.25" rod in it...very snappy combination for a motor that is good for an easy 7500 rpms if built right...so if it were me i couldnt justify putting a "383" crank in a 350 for more "torque"...i would stick a longer rod in there (6") instead of going for the longer stroke

it all comes down to what you are using the motor for...just my $.02

 

The issue of piston dwell with different strokes is really only a consideration when comparing different combinations of bore and stroke that make up engines of the same displacement. If you're only increasing the stroke (as in going from a 350 to a 383), the increase in displacement outweighs the other factors.

 

lol wow you pretty much said what i forgot. Speaking of the books, there are more than a few I need to stop being lazy about and pick up.

anyways i agree with your 327 comment although you would definately need to know what you are doin to keep it reliable and streetable with decent power.

One thing that got me by surprise was said by one of the guys at my machine shop. He said that when it comes to displacement vs power, a smaller displacement motor has the same power potential as a larger motor ( realisticly speaking ) only the smaller motor will have to turn more R's to reach it.

IE: 350 vs 327, say a 300hp benchmark. with set up being completely the same aside from the displacement( heads, cam, CR, etc) it would take the 350 say.... 5200 rpm to reach said HP. Now take the 327 with the same set up and you would have to spin it to say 5500 or a bit more.

These are just pulled out of the air figures but you get the idea.\


Now for the power curve. I am sure the displacement differences will show up in different curves like the 350 will come in at a lower RPM and probably be broader and less peaky.

 

That's true, but it also means spending more money on the smaller engine to produce the same power that could be had for less money on the larger one.

 

true... i mean if you take the same 350 vs 327 deal... it takes more money, and stronger parts to turn the 327 more R's.


ahhh good bout of stroker theory... makes my head feel good

 

I have a 412 in my Camaro (400 bored .060). I bought the motor already built so it wasn't my idea to bore it so much Everyone told me that it would overheat since the walls were too thin. But so far it runs mint. It does not run hot at all, always at 220 or less. I have a stock thermostat too. I do run an aluminum radiator and have wired my fan to a switch though.

I don't know who said it, but I totally agree that the GM production 400 small blocks aren't that great. If you really are going to make some serious power, your way better of buying a aftermarket block.

On a side note, I went to a car show, and some old hill-billy guy was talking about how he was putting a 327 crank in a 400 block. I really know nothing about this but I could immagine it would spin some good RPMs? He said he needed a bunch of custom stuff made. What is everyone's thoughts on this?

 

That comes out to a 347 on a standard bore block. If you're racing in a class that has a 350 c.i. displacement limit, it's not a bad idea since there would be some advantages over a regular 350. It would still be at a disadvantage compared to a 400 though.