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phred
04-07-2008, 01:01 AM
Does anyone have any thoughts on the relative merits for SBC 377 vs. 383? My personal application is a hot street car; however I'd like to hear about a broad range of applications. I know about the shortcomings of 400 blocks, therefore assume the use of Dart little "M" blocks. Over the years of fooling around with SBC (I'm 62) I have found short stroke SBC's easer to work with.

The water is warm, anyone want to jump in?

lun40119
04-07-2008, 03:35 AM
I don't like to swim, unless there are coeds :D but wouldn't the torque potential be greater with the 3.75 stroke for a hot street application. jmo, Im just a guy tryin to do it myself. Take care.

want-a-be
04-07-2008, 05:15 AM
If you're staying with the stock blocks. It's my opinion that you're money ahead to stay with the 383...better block by a long shot.

Buuuuttt....if you're going with the the Dart block. might as well go with the 400 ci. By todays standards the 3.750 stroke is still short. Depending on what you're wanting to do. Get you some of the Dart 200 or 215 pro 1s and hang on. I'd be more then happy to be able to help you out with your choice of parts with your build if you need it.

Just let us know what you're planning, and what your budget is. You'll get a few ideas from us around here.

Thanks, Don :cool:

WCRE

Awesome Bill
04-07-2008, 10:55 AM
I would use the short stroke largest bore (4.185-4.2) application here being it is hot street. The engine will need at least 8500 rpm with a set of well prepped heads, lightweight internals and you will do very well. What is the e.t. and mph your after and what weight do you have to be? Any other limatations have to be looked at before we could go any further. If your a do it your selfer, have fun, if you need help, let me know, the short stroke big headed small block will do the trick with this class for sure.

phred
04-07-2008, 12:38 PM
The car I'm building will be 3100 lbs. 5 speed (I'm old enough to know how to drive one), a good handling suspension & big brakes. However I don't want to limit this to my car alone.

Has anyone dyno'd both with the same top end? Did it show a difference in the torque?

Is there a difference in cam requirements?

What will the seat of the pants difference be?

lun40119
04-07-2008, 03:29 PM
Bill aren't you usually an advocate for big torque down low on street builds........how come the flip flop this time......just wondering? 8500 rpm street build.........

Awesome Bill
04-08-2008, 11:08 AM
hot street is very competitive and if he wants to compete @ the top, he will have to use rpm and larger heads to get the high hp #'s needed. The 383 set up will run very well @ higher rpm's but usually I run a shorter stroke with a big bore with those engines over 8500. The first 1" of downward movement is where you get your best band for the buck!

All that stroke and a lot of rpm will work but is a lot harder on parts. Maybe not much to anyone, but the shorter stroke in this application will run better. We just done a 370", 3.625 x 4.030 engine for a customer with old 195 cc Brodix heads fully ported and cleaned up buy me, and the engine produced 623 hp @ 7200. Basically, this is a short crank engine with a long rod. Anyway, 13.75-1 compression, one of our house cams that is over 10 years old, (can't find anything better). This engine has roller rockers, and 5/16 really good push rods which I hate to use. Mark just run Sunday in his 3180 lb Chevelle, 9.85 six times in a row and lost in the semi by going red. This puts the engine @ 600 rwhp. His mph was right @ 135 and he was crossing the finish line @ 7500 rpm. Now this is a fairly decent engine, but for him to go faster, he would have to run the engine harder. So now he needs 8000 rpm hp and only has 7200 going flat, how do we achieve this? Everyone has these ideas that we can just put a crank in it and it will run faster, NO NO NO, it will rpm out sooner thus putting his final rpm out to lunch.

Ever hear of cars falling flat @ the 1000, this is why. Hot street is a particular class where you have to gear and converter this thing to spin. If it was my engine, it would be a 3" stroke with a 4.25 bore. Talk about 9400 rpm and making plenty of power! We run a real 302 with Yates heads and the engine did not even make any power until 7500, we would shift it @ 9400. Car weighed in @ 2800 lbs we run 9.20's with it. And we were done. Did not make but 720hp so we could not go any faster until we turned it harder or done something else. We pulled gear out of it and it became slower by 3 tenths.

With small engines and high rpm power, gear and converter are the key. But little tires that are demanded to be run on these class cars want RPM to get it to the other end. Check out a 28" tall tire with a 4.56 gear @ 140 mph and a 5.13 gear, then factor in 7-8% converter slippage which you can not do without and You'll see what I mean.

phred
04-08-2008, 12:42 PM
Bill,
By saying "Hot Street" I meant just that, a street car. There will be a blast down the strip from time to time, however it will be my week end cruiser & Mustang crusher.

Please read my posts again.

lun40119
04-08-2008, 01:37 PM
So..............short but sweet, if you can spin'em, that is where the power is???

want-a-be
04-08-2008, 09:52 PM
What Bill is saying is totally true about the shorter stroke, and the class he is talking about. The 377 engine makes real good power across the board and into the upper RPMs. Jake thats kinda what I was getting at, last night, when we were talking about the next engine you're going to build for yourself.

Phred, since your not going to hit the higher RPMs and want some good lower end torque I'd go with the 383. I think Bill will agree as he pretty much said that in his last post. But if you're going to go with the Dart block go with the 400 inches. Make sure you internally balance the crank. You'll have a lot less problems down the road.

Need any help, I know I would be more then happy to help, and I'm sure Bill will as well.

Thanks, Don :cool:

WCRE

lun40119
04-08-2008, 10:12 PM
Right I was goin to use the 4.125 and 3.875 though...........That way with some porting the 215's can transfer from the turd to a real engine :D However, I would still like to spin that one like the turd.............what kind of cam do you recommend with that displacement to make peak tq around 5200 and peak hp around 7000 and be done around 7500?

Sorry for bein a thread hyjacker
my bad

want-a-be
04-08-2008, 11:01 PM
So..............short but sweet, if you can spin'em, that is where the power is???

Yes Jake,

Lets pick a torque number for the heck of it and move it around the RPM range a bit to see how it affects HP.

We know that ( torque x rpm ) / 5252 = hp

So if we took 500 pounds of torque and make it at say 5500 RPMs. We would have about 524 hp @ 5500 RPMs. Take that same 500#s and make it at 7500 RPMs. You would be making 714 hp @ 7500 RPMs.

Now thats just looking at 1 RPM of the whole sweep on the dyno. But you get the idea.

So lets pick a band of torque say from 450-400 ft pounds and it is 1200 RPMs wide. Lets say the Tq peak is at 5000 rpm and the 400#s is at 6200rpm. the Hp numbers at those peaks are 428hp/450#s @5000rpm and 472hp/400#s @ 6200. Then you do some work and you're able to make the exact torque numbers but at a higher RPM band. so lets say you went to a 6000/7200 power band. Those same torque numbers would net you.....514hp/450#s @ 6000 rpm and 548hp/400#s @7200 rpm.

This being said,.... you have to have a head that's able to support the cubic inches in the upper RPMs if you're wanting to make good power over 7000 or even higher. Thats why an engine builder is balancing head flow/quality to ci he is wanting to build.

If a guy tells me he is running a 434 ci, ( race engine ), that's making peak hp at 6800 RPM then I usually go right to thinking he is under headed for the package. All else being correct that is.

So much for the short version. There's alot of things we consider when we design an engine package.

Thanks, Don :cool:

WCRE

phred
04-09-2008, 01:32 AM
Ya'll need to read my posts. I'm not looking for advice on what combination to choose. I'm looking for a discussion about the relative merits of the 377 vs. 383 & no other ci. One has the chouse of two combinations almost the same ci (377 can be made 385 with a 3.5" stroke & 4.185" bore), using a different bore/stroke ratio.

If one was to build two engines identical except the B/S, how will the output be different?

What difference will one see in a car after trying both engines?

want-a-be
04-09-2008, 02:32 AM
Depending on the parts you use but making them as alike as you could. You would see moderate midrange and good top end with the 377. You would see better bottom end with the 383 and moderate top end.

But...a 383 can be made to run at the top end also. Of the 2 combinations I like the 383s better. Especially for your application.

Thought I had already given you my opinion of that. I'm not really getting what you're asking I guess. I can make about anything run very strong to about any RPM a person would want with the right parts/budget. But for the street the 383 should have the better bottom end to get up and going.

Don

phred
04-09-2008, 05:39 PM
What I'm looking for is real world answers of why to choose one over the other. Is the 383 better in a heavy car? Is the 377 better in a light car? Does a 383 work better with a automatic? Is the 377 better with a straight shift? All things being equal will one always be faster?

Is the 383 used a lot just because it's an easy way to increase cubic inch?

want-a-be
04-10-2008, 04:31 AM
When dealing with stock blocks on builds is when this make a difference. imo... Personally...I think the stock 400 blocks are junk and think they are a waist of a racers time/money to build one. They are just too crack prone in the center bolts out to the cylinders. YES....I've machined up lots of 400 blocks that are running for years. But I've had lots of them brought to me that were already cracked wanting me to repaire them. To me...the stock 350 block is a stronger block and with the 400 stroke they are a hard combination to beat.

377 or 383 doesn't matter. I internally balance them and make them both RPM the same. The 383 got it's popularity cause the STOCK 350 block is a stronger Block...imo thats the long and short of it. Myself...I think the 383 is the better combo of the 2 cause I can make them both RPM and the 383 will have better bottom end.

On the other hand...I think with the after market block, like the Dart, the 400ci is hard to beat. Unless you're willing to spend the extra bucks to get the better heads, the 23* stuff starts to fall a bit short when it comes to supporting the larger Small Block packages in the upper RPMs. Like a 434 for instance. If you're wanting to make power up near 8500 or higher. You're going to need more head then you'll be able to get in the 23* package. Even some of the 18* stuff falls short of what I'm wanting to do. But heads like the lil Chiefs should be able to do the job.

Hope this gets what you're wanting. I'm sure I'm going to be hit a bit on the wimpy 400 block comments, but thats my opinion and that's one opinion that won't be changed. Sorry for the long post.

Thanks, Don :cool:

WCRE

Awesome Bill
04-10-2008, 09:59 AM
Hot Street is a class of racing were we build the higher rpm engines, Kinda like SSO. We have to run a 28" tall tire and run 7.50s. I thought you were getting in over your head here. Yeah I would run the 383 because of the block issue and there are plenty of them. The 400 block is getting harder to find and most of them were very thin anyway. All that typing!

want-a-be
04-10-2008, 10:30 AM
lol...yea I hear ya

phred
04-10-2008, 12:23 PM
I believe in my first post I think one will find that I said, "assume the use of a dart block".

I'm asking what is the real world seat of the pants difference between the 377 & 383. I'm not interested in any other cubic inch.

Awesome Bill
04-14-2008, 10:55 AM
If you make 500 hp @ 6800 rpm with the 383, you will make 500 hp @ 7200 rpm with the 3 crank verses the 3 crank. Shorter stroke verses longer stroke and the same power is the EXACT SAME POWER. One hp is one hp with either engine. YOUR DECISION is what you want to use it for.

Here is your problem!. Your building the house from the roof down. You don't even have any idea how fast you want to run let alone what it will take to put you there. Here is a really good idea, you give us what your want to run, what your going to put it in, what gear and tire size you plan to use, what transmission your going to run and then maybe we can help. Nothing wrong with asking questions. If your building this thing yourself and just want some ideas, we will be off without knowing just exactly what you EXPECT when its done. Call your doctor up and ask him whats wrong with you the next time you get a general feel bad feeling coming on you and see what he says! HP is HP no matter what size engine it is, but it is how it is applied and most times will run the same e.t. if you have 500 from a torque engine and 500 from a screamer. Take your pick. My opinion, just build the 383 because, it does make more bottom end power and torque up to 6500 or so. hthelps

phred
12-12-2008, 03:53 AM
I see that this thread has been looked at over 1200 times. Does anyone else want to weigh in? Remember I'm not looking for advice. Read my first post carefully.

Fred

brougham
12-14-2008, 06:18 AM
I see that this thread has been looked at over 1200 times. Does anyone else want to weigh in? Remember I'm not looking for advice. Read my first post carefully.

Fred

go the 377 and in years to come if the power you have is not enough you can always build a strocker and make some real power

Awesome Bill
12-15-2008, 09:47 AM
short stroke big or bigger the bore the better. But, The rpm factor will go way up depending on cylinder heads and intake. So you question has many roads to choose from. Higher rpm engines have advantages with class rules on tire size. Longer stroke engines tend to make more torque and pull the hp curve downward. Either way, hp is hp whether it is used correctly is the what the question will be. Heavier cars, taller tires, less gear all play factors. So just throwing your initial question out there with exact usuage is kinda silly.

rbrduck71
12-28-2008, 04:45 PM
Sooo Not To Change The Subject, Big Rpm And Big Hp Cost Money!!!!! So A Guy With A 1400# Car Could Run Less Gearing And Lower Rpm Torque Motor And Do Alright On A 300ft Track Right? Or Am I Lost And Confused?
Rubberduck

Mikey R.
01-10-2009, 01:36 AM
ok I have make a comment on this because I got into the same discussion on another forum. I'm a novice engine builder compared to the numerous pros on here and by no means do I consider myself an expert. But I do try to learn as much as I can and make educated decisions based on my info.

I have built 383 engines for the street. They all shared a similar package. I cannot tell you how much them little engines pull thru the RPM range(seat of pants) excellent power from 2500-6000. I would go with a 383. Heavy cars need torque to get them moving. You don't need a big converter and alot of gear.

That's not to say I would rule out a 377. But considering that engine I believe won't make as much torque at lower RPM's like the 383(given same parts except block and crank) I'm gonna have to step up the converter and gearing to get that sucker moving a heavy street car.

Now as far as seat of the pants? I've been in one car with a 377, it made excellent power but had a 5500 converter and 488's. Not what I would call a practical street car. I have never seen a 377 on the dyno. I've seen 383's on the dyno with good heads and small cams make 400ft/lbs TQ as low as 3200 RPM, and carry that torque all the way thru the power curve.

Now with that being said, your car with a 5spd your choices are limitless. Certainly with a 383 1st thru 3rd gear its gonna be a tire shredder. On the freeway in 5th gear with the TQ from the 383 you could just roll in the throttle and that thing will move out of its own way easily.

I think we all can agree with either engine you'll make good power. You have to decide what is best for you.

I always go TQ for the street. Just my .02

Awesome Bill
01-10-2009, 11:02 AM
I agree 100% here but now you have the SHP block with killer machine work right from DART that needs nothing or expensive blueprinting to have a really killer engine. Bigger is always better with this type of application. The 3 stroke with a 6" rod will yeild a ton of torque and this 400CI will act like a BBC. JMO

SUX 2BU
01-19-2009, 10:22 PM
Maybe I'm wrong here and I'm no expert but I read through the thread and I didn't see any mention of this:

Is not the 377 vs. 383 difference simply a .030 overbore? What makes any 383 that I've ever heard of is a 30-over 350 block (355) and a 400 crank. If you do not bore the block 30-over, you get the 377.

If that is the case, is 7 cu. in. of larger bore that much of a big deal? Perhaps it is when you are talking about 500+ HP motors. I can understand stroke differences but as far as I know, the 377 is just a standard-bore 350 with 400 crank and stock 400 stroke.

Mikey R.
01-20-2009, 12:36 AM
yes you're right a 377 is a standard bore 350 with a 400 crank. I believe the person was talkin about a 400 block with 350 crank vs 350 block +.030" with 400 crank.

SUX 2BU
01-20-2009, 05:57 PM
That's what I figured. With the way most of the thread was talking about stroke lengths, it left me wondering. His original question was really just that of the difference that a 30 overbore would do in a stroked 350.

SUX 2BU
01-20-2009, 06:06 PM
That's what I figured. With the way most of the thread was talking about stroke lengths, it left me wondering. His original question was really just that of the difference that a 30 overbore would do in a stroked 350.

lun40119
01-20-2009, 06:35 PM
I was under the impression he was comparing comparable cubes with different bore x stroke combinations.

Awesome Bill
01-24-2009, 11:01 AM
that is exactly right, you could also go the other way with a heavier car and more gearing to match the hp and torque also. Just putting the engine in something without using is correctly is never going to get the maxiumum out of it. I tend to use less stroke when I am using higher rpms and ofcourse Nitrous. The torque you get from Nitrous is off the chart down low and it has to be used correctly. But with short tires and big MPH and more gear than I like, to make it to the other end, we have to spin some of these engines over 9000 rpm. Aluminum Billet Rods, Bryant cranks, very lightweight stable valve train parts are all needed to do this. Try to run 180mph with a 28x10.5 tire in any car. 9000 rpm + is normal. And thats only 7.60's The drag radial guys are now low 7.00's this year. They do have a little more tire but they have the rpm and engines to make it happen.

So if you want to run a short stroke big bore or long stroke smaller bore, hp is the same in either direct. Just some tend to use a ton more torque and you can use that to your advantage or disregard it and loose it. PACKAGE is always worth more than just what the hp of the engine does.

rbrduck71
04-24-2009, 06:17 PM
i hope im not hi jackin but is it wrong to think, 1400lbs car, 300ft track, tire

speed/spin is your friend (sand drags) a whole lotta torque with less gear would

work almost as good as high hp/rpm with a bunch of gear???

im thinking tq motor would be cheaper, but would this idea work?

thanks

Awesome Bill
04-29-2009, 10:38 AM
heavy rotational weight tires will hurt no matter what! Put 50lbs on your back and try to run. Now put 100lbs on it. Get the picture. Rotational weight is your enemy. Mud boggers need the front tires up on top to keep the car or truck up on top. Usually point to 3 points of gear difference is the key to the front being up on top. Tire bit not tire spin will always get you there faster.

widowmaker87
05-20-2009, 11:56 AM
I just quickly scanned this post from page 1 to page 3 so forgive me if I am wrong but, I think what this guy wants to know is,
If you have a 377 ( destroked 400 ) and a 383 ( stroked 350 ) with all things being equal Compression , camshaft, heads,RPM range etc. which engine would come out on top if they are both purpose built for the street.
In my opinion the over-square engine will always outperform a non-oversquare combination but you can build each and get about the same numbers from them until things get serious then its the oversquare combo every time.

Awesome Bill
05-27-2009, 10:42 AM
yeah if your running a specialty class like a comp index or pro stock. but todays street car and hot rods are not even close to that. You said it right, either properely place will work fine. Its your decision to make. I like the long stroke and smaller bore applications under 6000 rpm with street and mild race stuff. with todays blocks, we can have both, long strokes and big bores to open up the heads so its really just a decision on which one do I really want. Heavy cars, stock or mild converters, little to none gear means long stroke and small bore will beat your ____ every time.

phred
10-07-2009, 02:33 AM
That's what I figured. With the way most of the thread was talking about stroke lengths, it left me wondering. His original question was really just that of the difference that a 30 overbore would do in a stroked 350.

You are just a little off on your thinking. The 377 is a .030 over 400 Block with a 350 stroke. 4.155 bore & a 3.48 stroke. The 383 is a 350 bore with a 400 stroke. 4.030 bore & a 3.875 stroke.

phred
10-07-2009, 03:21 AM
The car I built for the engine in this thread is on the road. I built is as a 380 ci using a 4.155 bore & a 3.50 stroke. I used a Dart little M sportman block, Pro 1 Platinum 180 cc heads, & a Dart duel plane intake. I used a Scat crank & Scat 6" rods & SRP pistons. The CR worked out to 10.4, it runs fine on 93 octane gas. The cam is a Comp XR294HR 294 300 242 248 .540 .562 110. Quick Fuel supplied me (nice to live in the same town & have friends that work there) with a 750 mechanical secondary carb.

The Trans is a Doug Nash street 5 speed with a 3.28 low & a 1 to 1 high. The gear is 3.08 & the tires are 27" tall.

To say I'm happy with my engine is an understatement. It is very easy to drive. It pulls away from a stop with no fuss or clutch slipping. Wide open it quickly out runs my nerve & pulls strong all through the rpm (2800-6100) range of the cam.

Would a 383 be better? Maybe, however I bet my engine will get me all the tickets I would ever want.

Thanks for all the feed back from everyone.

lun40119
10-08-2009, 12:52 AM
You are just a little off on your thinking. The 377 is a .030 over 400 Block with a 350 stroke. 4.155 bore & a 3.48 stroke. The 383 is a 350 bore with a 400 stroke. 4.030 bore & a 3.875 stroke.

A 383 is 4.030x3.750

lun40119
10-08-2009, 12:55 AM
The car I built for the engine in this thread is on the road. I built is as a 380 ci using a 4.155 bore & a 3.50 stroke. I used a Dart little M sportman block, Pro 1 Platinum 180 cc heads, & a Dart duel plane intake. I used a Scat crank & Scat 6" rods & SRP pistons. The CR worked out to 10.4, it runs fine on 93 octane gas. The cam is a Comp XR294HR 294 300 242 248 .540 .562 110. Quick Fuel supplied me (nice to live in the same town & have friends that work there) with a 750 mechanical secondary carb.

The Trans is a Doug Nash street 5 speed with a 3.28 low & a 1 to 1 high. The gear is 3.08 & the tires are 27" tall.

To say I'm happy with my engine is an understatement. It is very easy to drive. It pulls away from a stop with no fuss or clutch slipping. Wide open it quickly out runs my nerve & pulls strong all through the rpm (2800-6100) range of the cam.

Would a 383 be better? Maybe, however I bet my engine will get me all the tickets I would ever want.

Thanks for all the feed back from everyone.

I like the combination, It is nice to use the bigger bore block. Really opens things up on the cylinder head side. I am glad it worked out for you.......quick question though, just out of curiosity, how come no 3.750 stroke in the 4.125 block......just curious.

phred
10-08-2009, 10:54 PM
A 383 is 4.030x3.750

That would be a long stroke! I don't what I was thinking, I know, I wasn't thinking. You know how us old people are.

phred
10-08-2009, 11:07 PM
I like the combination, It is nice to use the bigger bore block. Really opens things up on the cylinder head side. I am glad it worked out for you.......quick question though, just out of curiosity, how come no 3.750 stroke in the 4.125 block......just curious.

Lets see, don't like long stroke motors, always wanted to build a 377, or just flat didn't think of it.

I almost put a 3.25 crank in it for a 348 ci. About 20 years ago I helped a friend with a sportsman stock car. 3 of the rules were, 7" tires, 350 ci, & a 750 carb. One could spin the tires all the way down the straight. There were no bore & stroke rules. I wanted to build a 348 for it, however the driver & owner fell out. That was that.

Fred

phred
10-19-2009, 12:48 AM
The car I built for the engine in this thread is on the road. I built is as a 380 ci using a 4.155 bore & a 3.50 stroke. I used a Dart little M sportman block, Pro 1 Platinum 180 cc heads, & a Dart duel plane intake. I used a Scat crank & Scat 6" rods & SRP pistons. The CR worked out to 10.4, it runs fine on 93 octane gas. The cam is a Comp XR294HR 294 300 242 248 .540 .562 110. Quick Fuel supplied me (nice to live in the same town & have friends that work there) with a 750 mechanical secondary carb.

The Trans is a Doug Nash street 5 speed with a 3.28 low & a 1 to 1 high. The gear is 3.08 & the tires are 27" tall.

To say I'm happy with my engine is an understatement. It is very easy to drive. It pulls away from a stop with no fuss or clutch slipping. Wide open it quickly out runs my nerve & pulls strong all through the rpm (2800-6100) range of the cam.

Would a 383 be better? Maybe, however I bet my engine will get me all the tickets I would ever want.

Thanks for all the feed back from everyone.

I want to throw in a short update here. This afternoon (Sunday) with nothing better to do, I took a road trip with my car a 1967 (yeah I know another red Camaro) Camaro. I drove a 185 mile loop, other than off ramps I never dropped below 80 MPH. The average fuel mileage was 15.4 MPG. While that will never satisfy the green nut cases, I was happy with that.