right now im playing with the idea of a 377... im looking for a street/strip motor more on the strip side capable of turning somewhat high RPMs (6500-7500) i know a 383 can do that, but i hear they are better when you just want low torq, and due to the short stroke of the 350 the 377 is much better for higher RPMs. right now i have a 4 bolt main roller cam (vortec) 350 block, but i know where i can get a 400 for a decent price, i have no clue if its 2 or 4 bolt, what is it most likely??? and i have never driven anything but a roller cam motor, some of my friends are telling me id be happier sticking with my roller cam 350 over a flat tappet 377, any input from you guys would be appreciated

 

umm.... its all bull.

the 383 can spin just as fast as the 350. and make more power doing it. so if you want to be a bit more on the strip side like you said... build the 383.


a 350 is stock.
a 377 is the same crank as the 383 (3.75 stroke) in the 350 block but its not bored 30 over
a 383 is the longer stroke in a 350 block that has been bored 30 over.




so in otherwords, take your 350 roller cam block and build a nice lil roller cammed 383.

 

Do a search. This particular topic has been discussed over and over.

 

You can get a 377 2 ways. 3.75" stroke, 4" bore, or a 400 30 over w/ a 350 crank. Both come out to 377, but when people normally talk about 377's they are the destroked 400's.

Simply put, the more cubic inches you have the more power you will make. You will just have to make sure that you use intearnals that will stand up to the rpm you want to run.

Ben

 

i should have been more specific, by 377 i meant a 400 block, 350 crank

 

oh...

in that case.. dont be stupid.

build a 400... or a 406 if you have to go over.

 

Don't do a 377. If you have a 400 block, take the inches. The only time it makes sense to downgrade the motor like that is if you're inch-limited by your class rules.

For otherwise identical motors (and $$$) the inches will win every time.

 

exactly.

some stupid magazine goes out and makes a 377 with a 400 block for a specific reason, and all of a sudden, everyone and their momma wants to do it thinking it makes more power...

if you have a 400 block... build a 400.... better yet, stroke the 400 more. make it a 415 or somthing...

 

Well there have been people building 377's for awhile now. But yeah I agree that people like to just follow magazines when building engines.

stevedave, how fast do you want to go? I think that should be your question.

 

well right now i have a 350 tpi motor (not yet running and stock) and i just purchased a T-78 turbo, and it wont start making boost till 3000-3500 RPMs and i dont want a 2000 RPM powerband, so i need a motor that will easily turn 6500-7500 RPM's i've heard nothing but good about big bore/short stroke motors being great at fast/high revving, a guy i know and COMPLETELY trust has built a couple 377's and swears that if you build a 383 and a 377 and invest the same money into each that a 377 will be much better ESPESCIALLY for high RPMs... and a good friend of mine has a nova he had a 454 in it running 12.0-12.1 (in denver, so its about 1 second slower than sea level) then he swapped in a 396 crank, making a 427, he changed pistons and all that too, but kept the same compression, and the rest of the motor was the same, and he's now running 11.70's.. but im not hear to say the large bore/short stroke motors are better, im here to ask you guys what you think is better, so far im hearing that theres no replacement for displacement.. is there anyone that can prove otherwise????

 

nope.


and if you only want to goto 7500 you might as well stroke it too..... look around at some other 400 solid roller cam race motors... they rev that high...

its not like you want to go to 12k and build a formula one car motor.. you want a small block chevy. building a 400 (or larger)will give you the most small block chevy power.

 

For discussion purposes:
Let's dismiss the 400+cubic inches for now...

Say you overbore the 4.125" block .060 to get 4.185" and use the 3.48" stroke crank. That makes a 383. Now, let's compare the (2) 383 versions. What airflow potential, if any, would the bigger bore engine have over the smaller bore 383??? Also, would the shorter stroke allow it to "rev" quicker under the same load conditions??? What high rev potential would the shorter stroke engine have ovr the longer stroke??? Both have the same cubic inches...so IS there any REAL difference???


I can't answer based on my experience or hands on knowledge...
I think the only things to consider are less shrouding of the valves, thus potentially better airflow. I'm not sure which would have the "lighter" rotating assembly, "all things being equal" (if there is such a thing). I know each can be built to turn high rpms...but is one truely at an advantage over the other in this area?

 

That much I'll agree with.

On the other hand, a 400 will be better than either of those. It has the bore of the one and the stroke of the other. Think of a 377 as a 1/8" overbored 350; in reality, that's all it is.

You quote big blocks.... look at the 396. That's very similar in many ways to a 350; small bore, short stroke. The 427 is much like the 427; larger bore, same stroke. The 454 is much like the 400; large bore, and also a longer stroke.

Now, which one of those was your friend running 12 flat with again? Do you honestly think he would go faster with a 427 than he is with the 454? Then would it make sense that you would go faster with the 372 than you would with a 400?

The reason people build 383s is that they don't have a 400 block; or even if they do or can get one, it's not roller cam and doesn't have the 1-piece rear main seal. It's not because the 383 is a better motor than a 400. Same with the 372 (or 377, in a .030" overbore); it's also not a better motor than a 400. The only reason I can see for running that is if you're in a 6.1 or 6.2 liter limit class. If you're not doing that, then it's not the combo for you.

 

Or if you have a 400 with a wiped-out crank, and have a steel 350 crank sitting around. Then it might make sense to build the 377.

I'm not sure I'll agree with the 377 (as in 400 block/350 crank) being better for the same money spent on a 383 (as in 350 block/400 crank). 383's are getting about as cheap to build as 350s these days because of popularity. 377s, on the other hand, require relatively rare. So, you can spend more money on 383 go-fast stuff compared to the 377 which will be more expensive just to get it together.

I don't know if the magazine article that's being mentioned is a recent one, but the last one I saw comparing the two was about 18 months ago. The 377 made more peak power, but it didn't pass the 383 until over 6000 RPMs. And, neither engine was "optimized" cam-wise.

 

just for the record i havent read any such article, and would not build an engine based on one ****ing article

 

one more question has anyone here actually built a 377 (destroked 400) or personally known someone with one, and can therefor say for sure the 400 would make more power (i understand the combos make a huge difference, but still), because if this was true why would anyone run a 427 over a 454??? 427's are rather rare, especially compared to 454's, so i dont really believe that the ONLY people running 427's are the ones that had em laying around and didn't wanna buy a 454 crank

 

Yes.

The one I built ran just fine as far as that goes. It was for a customer eons ago, so I don't know what ever happened to it. It cost about $65 extra, at the time, to build that instead of a 400 (one set of bearing spacers). The customer had the same ideas as all this. Don't think he got it from a magazine article though, can't say where he'd heard of it. It may just have been that he thought the longer rods would somehow "make up for" the deleted cubic inchoes (gasoline molecules), I don't know. However all that may be, it ran just like a 350 that had been overbored a little more than usual; it definitely didn't have as much torque as a 400, and no particular RPM potential that was in the least bit unusual. The customer was a little bit disappointed in the end that he had actually spent money to slow himself down.

Real-world will beat magazine-article-world every time.

 

The son of the engine builder who did the heads on my 396 last spring has a friend with a '70 Chevelle with a 377 that he built for him. It's equiped and backed-up a lot like my engine, his car weighs a couple hundred pounds less going down the track. We both run out at Bandimere, and run very similar times (he quipped late in the season that he watched me run ahead of him in one round and dialed based on my red-light win ET). The builder just shakes his head when you ask him why the kid built a 377.

There are "reasons" - steel crank, internally balanced, it's what you have laying around...

And, there are nuances to the interactions of head flow, cam timing, rod length, etc., but in general, more inches means more power.

 

I had a 350 in my car until this past August, when I dropped in a 383 shortblock. Heads, cam, valvetrain, headers & exhaust were all resused from the 350. The only difference is a .5 increase in compression, a MSD crank trigger setup, & a retune of the fuel & spark curves. Results:

350 best 12.895 @ 106.21

383 best 12.031 @ 113.11

 

The 33 cube increase did not net you another 7MPH in the quarter with the same engine parts... that's laughable. It sounds like your gain was more from the tune.

BTW - I've got your burnout video saved... very nice

 

what amount of mph is equivilant to what hp in the quarter?

Ben

 

why would anyone in their right mind build a 377 with the same parts combinations as a 406? different combos for different motors. I don't know what magazines you're talking about, but the track results for 377s are just as good if not better than a 406, and they are more versatile (good for drag and road racing). there isn't going to be any real suffering down low, it's over 6 liters of V8, that'll make plenty of low end for a 3000 lb car

 

No, it was all the MSD crank trigger

I would agree some of the gain was possibly from the tune. However, I could not use the 350 tune on the 383 & expect it to run properly, could I? Point is if anyone here thinks a longer stroke won't produce more torque earlier in the rpm band, they need go back to high school physics class.

 

When faced with the choices, about the only way I'd do a 377 would be a longer stroke/rod 4" bore, and it would probably end up closer to 380 (I don't particularly like overboring unnecessarily). If I had a simaesed bore case, I probably wouldn't waste it on anything less than 416 cubes. And before I went shopping for a 400 case specifically, I'd hunt down a short deck Mk IV and start from there. But that's just my preference.

Everyone has an opinion, and most people have reasons for their opinions. Let's not allow the discussion to get too heated.

 

No, its not laughable!

In a properly built motor with all the Is dotted and all the Ts crossed a 1hp per cube increase will be realized, often it is more, or equal to whatever the original HP to Cube ratio was. With the additional .5 point in compression you could figure for a an additional ~2% increase in power. All other variables held equal.

Also for some reason people seem the think of 383s as a common setup these days and forget the true power they are capable of.

A 383 Vs. 350 is the same arguement as a 350 Vs. 305. Uhhhhhh hello!!

Go for cubes, its a no brainer.

 

making power is only half the game, using that power and having a large amount of RPMs in which to use that power is what will win races. who cares if your 406 is making 600 HP at the wheels if you can only use that power for 3000 rpms and your shift recovery keeps throwing you out of your powerband? I'd rather have the 377 that makes steady and strong power for 5000 rpms (from 3000-8000) and have my shift recovery right at 3500 and wind it out a 1000 rpm past peak. rpms can and do make a difference when you are racing.

 

That makes no since. If you are droping out of your power range you probably are geared wrong for the setup. Also from everything I have seen, you tend to get a wider power band with more cubic inches. If you build a 400 with the same rpm in mind as the 377 the 400 will be ahead. Not to say that you cant make power with a 377, but you are dumping cubes down the drain which makes no sence in my opinion.

 

you are looking at things too much in black and white. we can all agree that a 350 is a great motor and is capable of running into single digits just fine. a 377 is simply a big bore 350, a 350 makes plenty of torque due to its stroke, and a 377 will make more because of its larger displacement and same stroke, a huge bore with the smaller stroke will yield a much stronger top end you necessarily won't find in a larger motor unless you . that's why it's more versatile. and no, a larger motor won't yield a bigger powerband, it will yield a FLATTER powerband, not necessarily a bigger one. all this is relative to how you build though. a 377 will make more power than a 383 and 406 of similar builds as will a 302 over a 305 or 327. same applies for BBCs, 427 has always been a better motor for racing than a 454. the only really high power, mild and wild builds based off a 400 block that yielded more power than a 377 was a 434, but you can't use a stock block for it, crank won't clear the camshaft, and they really don't last long. there is no such thing as dumping cubic inches down the drain, if you want to rev like a 377 or a 302 with a 350 or 406, you'll need far stronger internals and the longevity won't be as great as with a 377. sustained high engine speeds will be better with a big bore/short stroke motor than a big stroke motor. anyways to each their own, I tend to like top end runs as much as going from a dig so a 377 is in my future plans

 

i'd like to say thank you to all who support the 377, and i'd like to add a couple of things...
in an N/A situation i would agree that more cubes = more power, for the most part at least, but that T-78 turbo i bought (i never actually got it though, long story, so im thinking twin T-49 - T-52's) anyways the T-78 came off of a 3.0 liter supra making 784 RWHP, which is already more than i need... not more than i want but more than i need, also i have an article on some famous racer i forget the name who has a 283 twin turbo in a grand national running low 7's, his is a race only car but still weighed 2900 lbs, im not trying to run 7's but my point is in a turbo motor i can achieve more power than i'll ever need in a 377, i was actually considering a 352 (400 block 327 crank) aswell, and if you still think im an idiot and im doing things the hard way i do have my reasons..... the short stroke make high RPMs (over 8k) much easier on the motor, so i dont have to rebuild every season, the long rods help with quench and some stuff i dont really understand yet, but in short it helps to reduce detonation which is a concern considering the high boost levels. and lastly i need the high rpm powerband because the turbo's wont spool till 3500+ rpms... and so in order to have a decent powerband i need to turn it to 8000-8500 rpms maybe more who knows, and while you can turn a 400/414/427 etc this high how long can it take it??? a shorter stroke motor can definately take it for a lot longer period of time

if im wrong then i guess i'll learn my lesson, but from what i've seen from other people's projects just about any small block with good sized twin turbos will make the power im seeking and so i am positive i wont fail

 

8500rpm i hope you have a big wallet.

a typical winston cup motor only turns 9000 rpm.

and think of all the strict tolerences those motors go under.

also, if you want a powerband that high, your not going to have a very stretable car, because a 377 isn't gonna make power from idle to 8500rpm.

and what you are saying doesn't make any sense.

let me get this straight. because a 377 shares the same stroke as the 350, it will be able to "rev" higher than a 400....???

stroke of the motor is going to have little effect on the operating range of the motor. the quality of your rotating assebley, and the quality and careful selection of your valvetrain is going provide a safe high reving engine.

besides the fact, these are probably all just pipe dreams.

 

a 377 will make the EXACT same amount of torque down low as a built 350, it'll make a whole HELL of a lot more HP top end thanks to its huge bore. A small stroke motor, especially in relation to bore, will rev higher, quicker, and safer than a large stroke motor because there are less forces on the crank at x rpm with a shorter stroke. obviously, balancing is important to maintaining the strength of the block. I don't get why people think a 377 is not going to have any bottom end. 300 ft. lbs and 200 HP at 2000 rpm is more than a 305 makes at peak, thats PLENTY of low end. and pulling 700 HP up top at 7000 and 600 ft. lbs at 5000 rpm is great for a race motor. bigger bore will always be faster than a bigger stroke. Bigger stroke will tow better. And of course if you have a motor that is operating between 4000-9000 rpm you have to GEAR it properly. 4.56 and 3000 stall, don't whine about streetability if you want to go fast. I have never seen or heard anything bad about a 377 except from old school pundits who think cubes are everything. a 377 will out run a 383 in a car of the same weight, as well as outruning a 406.

 

if bigger bore is always better, then

-why are stroker kits so popular.

-why did GM design the LS1 with a small bore and large stroke

-why are winston cup motors small bore and large stroke

your talking out of your ***

also, 300lb trq @2000rpm is 114 hp, not 200.

horsepower is dependant on torque and RPM

no 377 will EVER make 300lb tq @ 2000 rpm, and make 700hp @7000 rpm N/A, because 700hp@7000 is 525lb tq@7000. no 377 is going to have that much area under the torque curve, its simple not possible N/A.

engines like that only exist fairy tales.

put down the crack pipe.

 

The reason a bigger bore is better is valve size you know airflow. I have heads with 2.200 intake valves that will only fit .075 over 400 blocks. ( thats 4.200 bore small block.)

Its the low cost way to get more inches. If you can find a company that can sell big bore blocks for the price of a cast stroker crank and make money buy stock in them.

The LS1 has a bore and stroke to match its factory low rpm range ( less than 6,300 rpm and thats low in my book)

You are wrong on this one also. All cup motors are 4.120 to 4.130 bore and thats about 400 bore size and the stroke is 3.300 to 3.330 and you can tell me if thats small bore and long stroke.

Yep someone is.

Jerry

 

Take 2 motors of the same displacement. One with short stroke big bore, one with long stroke small bore.

The big bore short stroke will always have wider power band with the most area under the curve, however the longer stroke smaller bore motor will make peak TQ lower, however maintaining the power is where is where the long stroke motor falls out and the short stroke motor shines.

Rule of thumb is the short stroke big bore is more adventageous when spinning 6000rpm and greater. The mechanical advantage of the longer stroke is lost in the higher RPMs as it is much more efficeint to fill the bigger hole with less arm as the motor revs up.

However if there is a displacement differnece the arguement starts to lose ground.

 

Everyone dig out your Chevy Hi-performance, Oct 2000. They did a cool 383 vs. 377 shootout. They made every attempt to make the two motors exactly the same. They had the same heads, carb, cam, intake, compression, rod length, rocker arms, same everything.

The difference is the 377 is the 400 based motor with 4.155/3.48
and the 383 is the typical 4.030/3.75

There final conclusion: "As you can see both engines are very close in power. It appears the 383 would make a better street engine, while the 377 would make a good road-race motor if you were willing to wind the engine a little tighter. With better cylinder heads(they used Trick Flows), the 377 might end up with a more significant increase in horsepower, but both engines are winners in our book."

 

if this is the article you speak so highly of then yes.. reading this article does make me wanna build a 377, i think it has a great powerband, would be very streetable, and make plenty of power.... although i wanna drive it on weekends im not really worried bout street driving, i want a little more RPMs out of it, and a lot more HP, but thats where the boost comes into play, and so im not interested in doing this combo

 

Cause every dufous ****** out their wants one believing cubic inches are the end all of performance. You can only increase the bore .060 MAXIMUM, there are no "bore kits" you need a different block.
why are 388 ALL bore LS1s running single digits all motor? don't ask dumb questions

rofl, 4.125 x 3.25 isn't small bore large stroke. a large stroke engine would be the absolute ****tiest damned motor you can have in a car that is maintaining high rpms. why does a 358ci Winston cup motor make 700 HP with restrictor plates and a 390 cfm carb while a 4.060 x 3.48 360 cid can peak out around 600 HP with the best flowing everything on it all motor?
this coming from someone who has probably NEVER raced in their life.
you rely on a guestimate equation way too much. bench racing proves dick. go play with desktop dyno you git.
yes HP is a function of torque, but your little equation HP = (tq x RPM)/5252 is nothing more than an estimate it's not precise or exact and isn't subject to any environmental factors. and again you've never seen, raced, built, or dyno'd a 377 so you obviously have no idea what you are talking about since you live in la la land.

yip, those single digit fairy tales putting your 383, 406, and even 434 SBCs to shame time and again at race tracks and drag strips nation wide.
put down the magazines, shut desktop dyno off, stop equation racing and go talk to some people who have 377 powered cars. or better yet, RACE THEM

 

steve, do the 377, talk to some engine builders who've had experience making a motor like that and ask what cam they recommend to meet your needs and build the motor around that. 377 isn't gonna be some yeehaw tractor pull 383 motor, it's gonna be a fire breathing street demon that if you wanted to could send a stripped 3rd gen well into the 8s with a shot of crack or forced induction. more commonly you'll have a nice street thumper than runs 10s

 

I think your taking some of this personally??? This is a disscussion board, not an argument board. Every post ive seen by you has had some sort of name calling and strong wording.

Chill out, you can tell people what you think is right till your blue in the face, and theyll still do it their way, even IF you are right or wrong!

I couldnt find my picture of the punk kid leaning on his 5.0L saying "shut up or I'll argue with you over the internet" not saying you are a punk kid, I dont know you, its just the argueing over the internet is the part that i found soo funny.

 

i agree 100%


lets put it this way.

if you were going to spin a 3.48" stroke motor to spin to 8.5k. you need a top notch shortblock... agreed? great.

if you were going to spin a 3.75" stroke motor to 8.5k, you would need more strength by the numbers, however, the same type of shortblock would be used as the 3.48" stroke motor.... so you end up with a similar cost.

yes, your piston speed will be insane. but its not any more impossible then the 3.48" stroke motor.

in anycase, what you described is a all out race motor. so this case is moot. either you have a fat wallet to do this or you dont.
im sure with enough cubic dollars you can do anything, but the more cubic inches you combine with thoes cubic dollars, the more power potential you have there.


you guys are arguing over nothing. why does the 377 exist? to meet displacement rules. why are thoes rules there? to limit cost and power.


noone here with a 377 at their disposal is for them, and only people who like the CONCEPT are for them. the idea is great, but its like saying, lets make a 302s stroke even shorter so it will rev higher.... sounds great, but then you end up with less power because you find that no matter how fast you spin that destroked motor, you can find a way to spin the bigger one the same speed... atleast talking our V8s.

 

Mr. Dude,

You beat me to it. I was going to suggest that we all forget about the long throws, and start building 302s. By all the "evidence" presented, a bore/stroke ratio like that should be capable of four-digit HP and TQ - even more with a TPI intake on it....

 

If you listen to the guys that were around in that time people were ditching 302's for 350's when they came out because they made more power too.

 

yea, athough to be honest, i wouldnt mind have a 302... just cause.

totally besides the point though.

 

Personally, I think a physics lesson would be in order.... maybe I'll write one up for the tech articles, with real facts about how a heat engine works, so we all have something factual to refer to instead of nothing but a bunch of BS from people with no education or experience.

 

ooops

 

yea, i cought that too... that was a pretty stupid thing for him to say huh?

you give the definition of what hp actually is, and he acts like its some real world force instead of the mathmaticly devised number that it is.

 

Hey guys....everyone thinks I am nuts running a 305. More cubes would be nice but the 305 was recently rebuilt before old man retired. 8.11 @ 85+ in 1/8 is fun. Especially as my son was under the immpression that the 305 was a real dog. Even w/305 lack of useful torque. If it was a 302 motor, I'd probably be a half to three quarter second faster.

350 v. 377 v. 383??? All have their own benefits..... Though I have not messed with cars in last few years, 20 to be exact. Big bore short stroke has some real advantages in valve area. This is a major restriction on Olds and Buick motors. Even with two cycle engines (ex-Kawi triple racer). Nascar engines love a shorter stroke, bigger bore setup. Everyone must make determination as to what fits them best. I understand the argument for a 377 over a 383. I also understand why the 383 fits many applications better. 383 is now common because it give best all around adaptability at a reasonable price. Purpose built 377 may fit w/turbo better.

Do not give the guy a hard time when he should be applauded for thinking everything through. He is looking for advice.

 

Same reply, different thread.

Find me a pro race team that runs less cubic inches than the rules allow. Good luck.

 

and cubic inch restrictions don't stop 302 fords, 377 and 434 SBCs from running approx the same times at the strip. a function is simply a relation between two sets. since HP is is merely a relation of torque and engine speed, how is it not a function of those two variables? RB how about you write it up now and post it here oh mighty engine ***.

 

generally, its the all important cubic dollar that slows them down the most.

btw, you DO realize there are other diffrences between motors besizes the displacement right? same with the car.... foxbodys can be pretty damn light.


not to mention most classes have a displacement/weight rule... and thats MENT to keep thoes balances in check.