OK you guys I need some help. I have heard a couple of bad things about a 383 stroker motor. I have heard that since the stroke is longer than stock in a 350 small block, it creates more stress on the crank and piston walls. Overall reliability is not very good. I also heard that if you want to create more power and still have a good reliable motor with a 350 small block the way to go is boring your motor and staying with a smaller stroke. My question to you guys, who really know what you’re talking about, is how should you create more displacement for a street motor? Bore or stroke. And does it make a difference in reliability and engine life if you use 6" rods instead of 5.7" rods. My uses for the motor are for street use and occasional strip use, perhaps just a couple times a year.

 

what's been your experience i see you have one in your car already?

 

I am in the process of building one, just something that I have heard and concerned about the life and reliability of the motor.

 

There have been plenty of tests between a 5.7 and a 6" rod. For Hp, there is maybe a 5 Hp best case scenario difference in the rods size. The longer rod is just supposed to last longer, because of side loading I think.

 

Rough education for engine dynamics (generally speaking):

Big bore / short stroke:
Example: 69 Chevy 302, 4" bore (like a 350) with a 3" stroke (like a 283) Chevy used this foundation to make a killer high rpm engine. This bore to stroke ratio lets the piston speed increase at a faster rate. The advantages are better power responses at higher rpm levels, like road racing type events.

Increase the stroke significantly and you get different results.
Example: 383 Chevy, 4" bore (like a 350) with a 3.75" stroke (like a 400) By increasing the stroke you have not only increased the total size of the engine, you have moved the power band to the low end of the rpm scale. This engine, when equipped with all of the same parts as the 302 (any head/cam combo) will pull much harder through the low rpm range than the short stroke model. This engine will not rev as fast in the upper rpm ranges. The engine will make more horsepower and torque than the 302, but it will do it at different rpm ranges.

If you're looking for a street killer, cubic inches rules. If you use the exact same intake/carb/cam/heads/exhaust, the larger displacement engine will win on the street. If you're doing some sort of top end, bonneville style racing, the results may differ somewhat.

I think 383 kits are cheap enough now that there's no reason to build a 350 inch engine anymore. Not for a street killer, anyway.

After it's all said and done, you can still ebay a 400 cheap enough to go even bigger.

I'm not trying to be a rocket scientist, just putting some practical experiences on paper. Good luck whatever you do.

 

Couldn't agree more with the above....well put!
Theres a reason naturally aspirated "Mountain motors" are popular at the dragstrips...570 cubes plus!!

Getting the power to the ground becomes the next problem....

...build the 383 and don't look back.

 

Long story short,a 383 will last as long as any engine,given the same treatment.
If the longer stroke really hurt anything,where did the 400 come from?Granted it had shorter rods,I had a 5.7 rodded 406 in a truck that had right at 90000 miles when I sold the truck,and it showed no signs of giving up.Build your 383 right,treat it right,and it'll last just as long as a 350,it'll just be more fun to drive

 

The Ford 300 I6 has a 4" bore and a 4" stroke. Those engines are bulletproof and last upto 300,000 miles easily.

 

Thanks a million for all your replies to my issue. I just can’t wait to finish building this engine. I guess because I am building this motor I am very concerned about the way it will run and the reliability of the engine. Right now I should get my damn car running. Hell it has been about a year, but I know that it will be worth it once my car is running. Thanks a million for all the imput you guys have given me, and please if you have any more information to share pleases do! Once again thanks for everything.

 

The best option is to build an engine with as much bore and as much stroke as you can, and spin it as fast as you can.

 

You dont want to spin anything with a big stroke too fast or the front of the cars going to look like the 4th of july when the rods come through your fenders and hood

 

Then you didn't build it strong enough, or spun it too fast.

 

When it comes to the question of boring or stroking a motor, everyone is gonna have a different opinion. Boring the cylinder increases your c.i.d., but some testing has shown that it increases the likelyhood that you could develop detonation problems if the bore is too big. This is on an aftermarket block by the way. Stroking a motor makes more cubes, but if not used with a 6.0 inch rod, the rod length ration will be changed enough to create side loading problems like Ede suggested earlier. The fact of the matter is that there is only one rule you should be following here. "There is no replacement for displacement." Bore and stroke the motor to the 383 limit and don't worry about all the different opinions. On a street motor that's not running an insane amount of compression you shouldn't have any problems with detonation. The one aspect that no one has mentioned, but is awesome none the less, is that stroking will get you a lot more torque down low. Usuaully when you select a cam, you have to make a trade off between torque and horsepower. With a stroker, that isn't the case. You will already have a lot of torque down low, so you can afford to have a cam that's geared a little more towards horsepower and not have to worry about how much it will kill your low end torque output. If anything, you should kill a little of that lower torque in an effort to increase your chances of hooking that car up,lol. I would use the 6.0 inch rod to correct the rod length ratio and then build it. When all your buddies are still whining about you whippin' their a**es, you can smile inwardly as you climb back into your ride and crank that 383, which they said would prove to be unreliable, and glance at the thousands of miles you've put on the odometer as you crank up and head out for some more fun.

 

I think that I was the one to suggest that.

 

Just to reiterate, stroke has no effect in torque production. Engines of the same size with different bores and strokes will make the same power, pretty much everywhere.

That being said a larger bore motor will make slightly more hp because of the valve unshrouding and the potential to use larger valves. But as said before having a large bore creates other bad problems. It will increase the amount of timing needed, reduce efficiency, cause more emissions and cause detonation in extreme cases.

This is partially why all new engine designs in cars have a relatively large stroke and small bore.

It is better for everything other than max hp output at extreme rpms.

 

I stand corrected and apologize profusely to Tibo, who was the one that made the comment about side loading. Sorry about that. M.E. Leigh makes a good point about the valves being unshrouded with a bigger bore. This would really be beneficial if you were using a different degree for the valves. Like in the Brodix 18 degree heads. You just have to watch how far the bores get opened to avoid the other problems. Hope this helps you make your decision.

 

If your were restricted to a max CI due to rules, A larger bore shorter stoke would be the best combination.

Look at NASCAR they use a larger bore and a shorter stroke. Similar to a 400 block with a 327 crank. I said similar I am not going to do the math, but the comparison is valid. If there were a better alternative they would use it.

All of the issues / ailments of the large bore short stroke can easly be overcome provided the componets are optimized. The real benefits that are factual are slower piston speeds , the ability to use a longer rod and less ring drag and friction.

WHAT YOU NEED TO DO IS BUILD A 383 the traditional way. Do not use 6 inch rods or get fancy. The block it going to need to be clearenced for the 400 crank anyway dont throw 6 in rods to complicate the process more.

Another piece of good advice, unless you own a machine shop or know someone who does buy one that is already build by a reputable source. This is a good use of your money and TIME.

The 383 would be great for your intended use and you dont need to spin it to make great power. RPM means "ruins people motors". This combo is tried and true and you will not have to recreate the wheel.

Good Luck

 

If I wanted a 383 personally I would want to do it with a 400 block and a 350 crank. This is also a tried and true combo. Most people would say if you have a 400 just build a 400 though. If I were looking to race or for performance, I'd do the big bore 383. But if you just want more power and will shift not much higher than 6000 rpm do the small bore/long stroke. It's considerably cheaper to build a stroked 350 than a destroked 400 even though all around it might have a few advantages. I believe the 427 LS7 is a large bore oversquare engine. Ferrari's also have usually used a big bore compared to stroke design. I've always wanted to do a 400 block 350 crank build just because it is different and my uncle built one once that ran great. Hot Rod or Car craft just did a dyno comparo on the two 383's earlier this year. They both had the same low end torque and made similar power through all rpm. Hope that helps.

 

I know two guys with factory 400 block based engines that lost cylinder walls. Both were .030" over, both were raced (one was race-dedicated, the other driven to the track). One was 4" stroke, the other 3.48" stroke.

The race-dedicated one now has a Motown block and 3.75" stroke - and it's faster than it used to be (other changes along the way, of course), and has lasted longer than the factory block did. The other guy is still down, to the best of my knowledge.

Best option: Both bore and stroke, just do it with an aftermarket block. Otherwise, stick to the factory 4" bore and whatever stroke you think you can deal with.

 

To my knowledge Nascar racers are using a 350 Bowtie block that has the lifter bores opened to the size of the Ford lifter in an effort to gain more valvetrane stability. Chrysler is always yelling about having to modify their blocks to accept Ford's smaller lifters. Some say to build a 383 without 6 inch rods because of clearance problems. I-beam rods are very helpful for just this sort of problem. Most aftermarket companies even machine the rod bolt clearance for you. RPM's won't ruin engines if all the correct parts are used when you build the motor. The stock rotating assembly can survive 6000 RPM's for crying out loud!! If you don't believe me, ask anybody with an LT1 who's wound out the gears and shifted at 6 grand or higher. As a final point, if you use an aftermarket block like the World Products one, it's already clearanced for a 4 inch stroke. A 3.750 stroke isn't gonna even come close to being a problem.

 

edited

 

I pointed out the advantages of the aftermarket block already. If you intend on building a high RPM engine then you should do the homework. Otherwise your hard earned greenbacks are going to waste. SDIF may have clearanced his block, but the aftermarket block doesn't need that. How much is spent on machining costs? 600 bucks or more, at least if you get quality machine work. And don't forget the cost of getting the block in the first place. Most of the engines I've seen are going for anywhere between 200-700 bucks. Now add that to your 600 bucks in machine work and you've got 1300 bucks rapped up if you got a low mileage engine in excellent shape. For a couple hundred more greenbacks you could have a block that not only was already machined and ready to go, but it makes the stock block look pathetic when it comes to cylinder wall thickness. The aftermarket block still has at least 5 more overbore machining that it can survive. That's 5 more rebuilds with the block bored .030 over every time to ensure a round bore. Will you get that with your stock block? No way. And you can't get 383 cubes if you don't overbore the block. The 5.7 inch rod in the 383 combo lowers the rod/length ratio to a less desirable number. The 6 inch rod restores that favorable rod/length ratio. This is important to this combo because he wants longevity from the motor. The 5.7 rod would create side-loading that would push the piston into the outboard cylinder wall creating more wear on the rings, piston and cylinder bore. That is the reason for the 6 inch rod suggestion.

 

Since you guys are on the topic, Do i have this straight

boring out a motor will cause some more torque, also will going with longer rods and shorter pistons? Should I consider doing any of this on my base 350 thats on the stand naked.

just wonderin

 

By RPM ruins peoples motors I mean that if two equally prepared engines were put on a stand and run continuely one at 4500rpm and one at 7000 the 7000 would break first. (This assumes that the valetrain harmonics were suitable for both engines at all rpms)


I am not a drag racer, but was at one time. The best time that I achived from a stock 305 tpi and t5 w/3.42 gears were 9.17 in the 1/8 of a mile. I could run 9.20 to 9.23 all night long and was usually my dial in. I did this by shifting at 4200 rpms without lifting. Shifting at 6000 result in 10.00+ times and slower mph. My point here is that at some point usually lower than you think additional rpm do not result in continued liniar acceleration. I belive that if a shift "throws you back in the seat" you have waited too long to shift because you have stopped accelerating.
My point was that there is not a need to rev a 383 high to derive improvements in performance.

 

Been there done that, by that I mean opinions, and information.
I read, and listened for 2 years until I thought I had enough then, I dove into it for 6 more months before actually buying anything.
I chose a Motown 350 4-bolt main block, it's a non-roller.
Bore 4.060" x 3.75 stroke, with 6" rods, 6" rods simply because the rod/stroke ratio is very close to that of a 350. 10:1 compression with aluminum fast burn heads. It's a keeper that's why I chose the Motown.
I didn't have any clearence problems, and I didn't have to use a small circle base cam.
It's a street car, but I may take it to the track someday.
I kept the TPI system because I really like it, I have modified it a little, and upgaded the spark, fuel, exhaust, and control system.
I can't prove it's a 388, but that's what it is.

Teh headers was all I did to the exhaust, haven't decide on what muffler to use.
It would probably sound alot different with a carb, and a larger cam, but, like I said, I'm happy with it.

 

I have a better idea: How about the two of you going back and editing out the crapola from your posts - you know, the rules-violating personal attacks? Both of you are out of line, and if you don't do something about it, I'll just delete both of your posts. I don't really want to do that, since there is some correct tech data in there, but the rest is unwarranted, uncalled for, and unallowable.

 

Let's get this straight: You don't get a larger bore by boring out your block. You get a larger bore by getting a different block.

The most you can bore the typical 350 block is .060" over. That is insignificant with regard to increasing the cubic inches, and is only done to provide straight and clean cylinder walls for the pistons and rings to go up and down in.

The Motown blocks are available in 4" bore, with capability to be bored out to 4.125" and beyond. Don't ever figure on being able to do that with factory 4" bore blocks.

 

Just to clarify SDIF, I was never your enemy. I hope you're not taking any of this personal because I wasn't. Whether or not we agree on how to build a motor is immaterial. In fact, all it means is that we each have our own way of doing things. Maybe you're right or maybe I'm right. How we feel something should be built is immaterial because in the end it comes down to the original poster of the thread weeding through all the info and making the choices that are best for his needs. In that respect, I'm sure you'll agree that we've both contributed a lot of information for the original poster to digest.

 

Irocracer07 Man

I know you are not my enemy, you have a camaro.

post edited.

 

Are the Motown blocks available with 1-pc rear seal and all the stuff for the factory roller cam?

 

Mine is a 2-piece rear seal, and a non-roller, but that was 2.5 years back I used a one-piece oil pan rubber gasket. The Dip-stick can go on either side, but the boss needs to be bore through.

 

In all honesty I don't know if the block is available in a 1 piece rear main seal configuration. I've listed the phone number and website address for the Hardcore Store which is owned by the manufacturer of the Motown Smallblock below. Check it out.

1.866.225.9050
Calling hours: Mon-Fri 9AM-6PM EST. Closed Saturdays and Sundays

http://www.theengineshop.com/contact.asp

 

We both have camaro's,lol. My post were edited as well.
Seriously though, I'm glad we've cleared the air so to speak. Hope to see you on the boards and remeber what I said. It's america baby. Challenge and question if you believe there's a need to. Sometimes we learn something that way. Other times we teach something that way. As far as I know, the only stupid question is the one you didn't ask,lol.

 

Hey guys,
Well I know that I havent said much in this post even though I had the question about bore or stroke. I just sat back and read all the replies. I learned a lot and after reading everything I am now confident about the proformance and the reliability of my 383. Now the only thing that I have to do is finish the build. I guess this is a question that I should have asked a long time ago, like before starting the build. But I justed wanted to say thanks again for all the imput all of you have given me. This is why I love this site. I will talk to all of you soon!

 

Glad the info helped you out. Have fun with that 383. It'll be a torquey little sucker that will bring a smile to your face every time you mash the loud pedal.