Formula4Fast

i recently heard from a diehard, find-any-motor-combo friend that you can take a 400 block and throw in a 350 crank, creating a 377. SUPPOSEDLY this monster can rev upwards of 13 grand. i dont know, just something i heard. if anybody knows any info on that or if you could provide some links on info for this combo, please let me know.

mw66nova

iTrader: (13)

done properly with the right parts combo and the right amount of money, yes it can be done. there are advantages and disadvangtages to it. if your looking to roadrace where you want to spin the motor to high heaven, then it's a decent build, but for drag racing, it's not the optimal choice for average joe racer. now, if your in a class with a cubic inch limit and no power adder, then it may be another story (thinks to NSCA's Hot Street) but most of those guys are running much smaller cubic inch, so that may be a different story. (guys running 800+ hp from 331ci sbc)

speed88

Yes it can be done. As stated it is a 400 block with a 350 crank. And you can rev the guts out of it, of course it needs to be balanced and blueprinted, and some nice forged internals wouldn't hurt either to help rpm.

five7kid

iTrader: (14)

Welcome aboard.

Suggestion: Find the "search" button and go for a drive. This topic has been discussed quite often (mostly on the General Engine forum).

As stated above, yes, it can be done. Just putting a 350 crank in a 400 block won't make it rev to 13 grand, though. You'd have to spend all sorts of money on the internals required to do that (several grand on the valve train alone), rods would be mega-bucks, and you can't expect a stock factory cast 350 crank to do this, either.

No low-end power, completely unstreetable, would be blown off stop lights by 350's costing a few grand.

mw66nova

iTrader: (13)

don't go making generalizations five7kid, i know you are bigger then that...remember, this motor has the same stroke has a 350, making it very easy to make the power down low just like a 350, but the upper rpm range is what's going to be the advantage of this type of motor. please don't start the argument that the 350 will have more low end torque as a 377. maybe more than a 327 but not more than a 377. a 377 with the same heads and valve train geometery will make the same low end torque as a 355 equiped equally. the high end power will be more though. there is no reason that the bigger bore of a 377 will cause a lack of low-end torque.

25THRSS

Well by saying it will have the low end of a 350 because it has a 350 crank then why would it be able to rev higher than a 350 since ofcourse it has a 350 crank?

posbird87

if someone wants to know what its like to have no low end torque i'll gladly give them a ride in my escort. you will hug your engine, whatever it be.

this sounds like a sweet combo. isnt someone on here building one or has one built? i mean, stoplight to stop light is fun but being able to get it on on the highway without fear of running out breath sounds great too.

if it does lack some low end torque, would adding a supercharger help to get back some of that low end grunt?

RB83L69

Yeah right. And I suppose that somehow this magical combination of parts has re-written the laws of physics.... things like the speed of sound don't apply any more??

People who have never built one always get this great idea about how high it can rev. Well I've done it, and I can tell you, it didn't rev much different from anything else.

Think of a 350. It's got a 3.48" stroke and a 4" bore, right? Now thingk of boring it out .030". You get 3.48" by 4.030", right? Is the end result very much different from a 350? Now some of you may have, or have rrun across at one time or another, a 350 tha twas bored out .040", or even .060". A .060" over 350 has a bore of 4.060". You get a few more cubic inches, but we're not into textbook obsolescence range yet.

So just exactly what on earth is so special about a 350 that's .125" or even .155" over???? That's all a 377 is, when you get right down to it - a .155" over 350.

A few more inches, but nothing really special. The exact same rev capability as the same bottom end parts and the same heads and the same valve train (the things that really determine the rev capability, not the bore size) would have if they were in a 4" block instead pf a 4.125" one.

Put your feet back firmly on the syrface of the earth; nod as if you approve the next time you hear this crap; and pay it no attention. It's all BS.

mw66nova

iTrader: (13)

well, i wouldn't call it all bs but, i just got done with another argument in another thread and really don't feel like starting trouble, especially with you rb, cause i know you know your stuff. but the possibilities of a 377 revving higher than a 355 with the proper valvetrain/head design is higher. your right, a stock valvetrain will float valves and do other weird things. a common 377 properly prepared will have a shift point around 7500-8000, given the right cam/heads/intake/compression/carb/converter/gear.

just fyi: i am by no means supporting the 13 grand theory.

wesilva

iTrader: (35)

There has been a few articles in Chevy Highperformance, Hot Rod, and Car Craft magazines in recent years comparing the 377 to a 383 (400 crank in a 350 or 4" bore). The general consensus was that the OVERALL power band of the 383 lent itself more towards being a better street/strip motor. While the 377 did make more power in the high rpm range, probably because the larger bore unshrouds the valves, it wasn't enough to make up for what it lost in the lower ranges.

That being said, it appears that a 377 would be a great motor in a light car where a strong low end torque curve would create traction problems, while the 383 might be better in a heavier car like a 3rd gen Camaro.

five7kid

iTrader: (14)

If it is made so it has more power than a 383 (and certainly if it revs to 13 grand), it will not have any low-end torque.

If otherwise built the same as a 350, it will have more torque than a 350. If otherswise built the same as a 383, it's what RB wesilva said.

And, I was talking originally about the 13 grand thing.

So, how many of you have a SBC that winds to 13 grand?

How many of you have seen a SBC that can wind to 13 grand?

unknown_host

iTrader: (1)

It will spin more RPM than a 400 and will have more displacement than a 350. People in small tire classes like destroked engines because they make good power but wont necessarily overwhelm a smaller DOT tire.

25THRSS

mw66nova

iTrader: (13)

this is kinda what i was getting at.

Formula4Fast

the 13 grand was just a way bogus ball park number that i threw out, obviously overstating the actual rev limit. i was just curious about the combonation

Air_Adam

If you have a 13,000 rpm engine, it ain't gonna have ANYTHING at the bottom end at all, just like 5-7, RB, and a few others have already said.

Hell, an engine with that kind of rpm capability will probably not even idle below 2000 rpm, and probably won't make any really useable power untill 8,000 or so. Look at the Honda S2000 motors... they have an almost stupidly-high redline... 9200 rpm i think... they make 250 or so hp and a scant 160 ft-lbs... and thats probably up around 5000-6000 rpm too.

If built exactly the same as a given 350 combo, yes a 377 will make more power/torque than the 350 will, because its got 17 more inches, but if you leave the 400 crank in it and build... a 400... then you will be even more inches up and make even more power. Just like a 454 will always make more power than a 427 built exactly the same, and the 427 will always make more power than a 396 built the same way.

Riley's35089rs+

All ya need to make this combo work, is 6 or 7 guys to push you past the 60 ft mark..

ede

most i've ever got out of a 377 is 11,000 rpm, but mine was a dog :lala: :lala: :lala:

cgb

Maybe I'm just paranoid...I still believe the 377 is the result of a bunch of car magazines, and engine shops having alot of 400 blocks and 350 cranks sitting around from building alot of 383 strokers. Back then, there were no "custom" stroker cranks that normal people could afford, so you took the 350 block, found a 400 donor, used the crank and the rods, and used off the shelf pistons.... thus lots of 350 cranks and 400 blocks laying around.

Of course, everytime this conversation came up, I always asked...why not just build the 400? You already got one...

Later I learned to say that it's because ALL 400's overheat, they are JUNK, so just give them to me..


Somebody was looking at all this crap and decided if he could build it and have the magazines run an article, he could sell all these and make some quick cash....


Unless you have a 400 block sitting around and only a 350 crank, then it might be worth it on a budget....but that's stretching it.


In my opinion... you can NEVER beat this...


On a STREET DRIVEN engine, you can NEVER have too many cubes. The bigger you go, the faster you can go without putting as much strain on the engine...


HTH


Um... 13,000 RPM? The most I've PERSONALLY seen out of a small block was from one of Ed hoover's old destroked small cube motors.... he had a few homebrewed 302's that would hit about 10k RPM , but these were track only cars... and bottom end isn't much of a factor if you can leave at 6000RPM and actually hook :P

88IROC350TPI

I cringe every time I hear someone say "I wanna build a 327/302/377/ect so I can rev it!" There is nothing that makes a 377 have the ability to rev any higher than a 350 or any other sbc for that matter. Now, and I know its already been discussed above but I gotta say it again, if you spend all this money on the beefiest parts to build yourself "one of dem der hi revin' tree-seven-tee-sefens" that you wanna rev to 10k RPM think about how stupid it would be especially for a street car? To stay in your powerband you'd need like a 7000RPM stall and some 5.13 gears ...and a gas station every other block.

Wanna spin a motor high? Buy a import or a sportbike. Wanna make insane streetable power? Build a SBC the way they've been built forever.

unknown_host

iTrader: (1)

Shorter stroke means less distance for the piston to travel per revolution than a 400. A 3.75 stroke sb400 engine would have to do about 7.8% more work at the same given rpm than a 3.5 stroke sb377.

A 377 will have less problems with valve shrouding than a 350, which would promote better cylinder filling and in the end better RPM potential.

In my case I would go with a 400 because I like torque as you mentioned. But what about cars that cant fit anything bigger than an 8" tire under them?

88IROC350TPI

If you have a small tire car, even if you build a high-reving motor the result will be the same. For maximum ET you're still gonna have to leave the line in your powerband regardless of what RPM it starts at resulting in the same shock to the driveline. Weither its leaving at 3500RPM or 6000RPM.

ede

there use to be a beretta run in comp eliminator that was suspose to be a 250 inch v8 and suspose to have composite pistons and rods and turn 13k. i sure loved to hear him run. would loved to seen inside the engine.

wesilva

iTrader: (35)

Not to mention more extreme rod angle and piston side loading. The 377 is easily a higher rever than a 400 or 383 sbc...but not the smaller motors (350, 327, etc). The 400 is a great motor. Don't get me wrong...but like the Sherminator (Dick Sherman)says, "Big torque is useless if you can't put it down". A 377 has it's strong points. With the right gearing, it's strong points seem to be at the dragstrip where traction is limited or at a high speed run like the Silver State Classic with good aerodynamics.

25THRSS

If you have more torque you must have more hp. The same goes for a 377. You'll have less torque AND less hp too.

unknown_host

iTrader: (1)

The 400 will have a flatter torque curve which is what I would want since I can fit a larger tire under my car than someone who would be considering a 377.

PhoenixFB350

that sounds awesome, what was it based off of (which block and crank)?

PhoenixFB350

the point of building that motor is for racing only, you are supposed to build the motor to run it out to high rpms to make high HP, building a 5000 rpm 377 will not make much power, an 8000 rpm build will yield significantly more. and from my observation those short stroke motors seem to have very flat torque curves.
HP = (tq. x rpm)/5252
5252 is a constant derived from various other factors
so you can figure that if the engine is making 450 ft. lbs and making it at 7500 rpm, your HP will be 642 @ 7500 rpm. not too shabby for a lightweight race car if you ask me

25THRSS

right, so if it's for racing only, why not go with the bigger crank and make even more hp? The only reason not to is for a specifically CI limited class, otherwise the 400 crank will be faster any way you look at it.

PhoenixFB350

expenses as well... a stroker 400 engine running to 8000 rpm is quite a bit more expensive to build than a 377. and the specific impulse on the rotating parts in the 377 is a lot lower than a stroker because its travelling a smaller distance so you can get buy with "weaker" alloys and still get the RPMs you needed. it'd be cheaper but yes, a motor making 750 ft. lbs at 8000 rpm WILL make a lot more HP but it gets complicated from there, stroker motors tend to have a more mound shaped torque curve. it's all about how much you're willing to spend

unknown_host

iTrader: (1)

Small tire class where the low end torque is blowing the tires off. Not all classes do cars leave "optimally". Take the BFG drag radial classes for example, a lot of those guys leave on 15* of timing retard. Do you think that is optimal? No, but it makes them win their class...

25THRSS

This makes no sense at all. Nobody who wants to win will sacrafice all their mid and top end of the track just so it's easier to launch. You don't do that. You make changes in stall, timing, etc, not in less cubic inches. There is other ways you can launch better, one being less right foot, but if you want less low end you don't do something that will sacrifice your mid and top end as well. It's just not done that way.

ede

phenoix, no idea, other than a SBC. i'd guess an aftermarket block.

mw66nova

iTrader: (13)

this is wrong...look at the drag radial classes. the competetive guys are running much smaller motors with huge high end horspower, running 8.30's @180 isn't uncommon.

unknown_host

iTrader: (1)

We arent talking about sacrificing mid and top end, we are talking about motors with peaky torque curves. I would like to see you pedal an 8 second, 1200 horsepower sb400 out of the hole on the same tire that most 12 and 13 second street/strip cars are running.

unknown_host

iTrader: (1)

Thank you .

mw66nova

iTrader: (13)

oh, and don't tell me high revving motors don't have low-end torque...

five7kid

iTrader: (14)

I appears to me all we're "proving" here is there are niches for engines such as a 377. I seriously doubt, however, that any of these 8 sec DR class cars are running NA 377's.

Now, all you defending the 377, answer this question: How many people do you know actually running one?

Here's my "evidence": I spend a lot of time at Bandimere, and I have personal knowledge of a lot of cars out there, and hear the announcer say what's under the hood when a bunch more run. Grand total: Approaching 700 cars. According to John Bandimere, Jr., about 1/2 of the cars at Bandimere run a Chevy engine. Even with all the street cars and "sportsman" out there, about 1/2 of those Chevys are big blocks. Of the cars running faster than 11 sec., you can count the number running a NA SBC without taking your shoes off, including rails.

Of all those cars, I know of exactly one 377 - in a primered, rusted-out quarter panel '70 Chevelle driver. The engine was built by a local race engine builder (the car owner is a friend of the son of the shop owner). The builder shakes his head when you ask him about the car, saying, "I told him not to build that engine, but he insisted because somebody told him it would make a lot of top end power." Although several hundred pounds lighter than my '57, we run nearly identical times - and he has to take the back seat out to do it.

Suggesting a 377 for a 3rd gen driver smacks of "magazine mechanics". If you happen to have a clean, stock bore, bare 400 block sitting around, and if you happen to have a clean 350 crank sitting around, then you might be justified in building a 377 to replace your LG4. But, optimizing it is going to cost more than 350 or 383 parts would cost (not having to use a small base circle cam is one possible advantage of a 377). However, if you have to go out and buy block & crank, it makes a whole bunch more sense to build a 383.

wesilva

iTrader: (35)

Not to change the subject, Five 7, but drove past Bandimeir last month and the housing area is really moving in fast. I go to the Denver Super Chevy show but have missed the past two years and it really disturbed me. It's days are numbered, mark my words. Seen it 100 times.

mw66nova

iTrader: (13)

never once did i say that it is a good n/a street motor, and i do know several people that are running these with great luck.(not n/a and that was not brought up till now) i never said that the guys in DR are running 377's although built correctly, they will run well. this is debated on more often than not, and i am kinda sick of it. but the fact is, with the right amount of money (money being the key factor) these engines are deadly in competition. the nova i posted is a procharged motor.

five7kid

iTrader: (14)

The housing hasn't moved any closer in the past 5 years. The land between C-470 and the existing housing is owned by a family that doesn't like developement. They have been looking into moving for several years, the latest plan having been squashed by big bucks ad campaigns by PPIR.

I brought it up because it was easy enough to assume that the one(s) considering it on this thread would not have thought about it. Supercharged, turbo, or nitrous 377 (or similar large bore/short stroke combo) has some advantages.

unknown_host

iTrader: (1)

Your right, a lot of the fast cars are running 360 and smaller ci motors in the cheap street class .

I know people who have done these. If you hang out with the non-tubbed, box nova crowd they are really into the 350 and 377 setups with big heads and big SR camshafts.

I dont think this topics reaks of magazine mechanics as the current trend in magazines is big inch small block combinations.

D M N

big bore small stroke..... what will happend if you turbo charge it? where can you find a 400???

tpiroc

Production was very low on these guys. They were stuffed into vans, picups, station-wagons, and big cars like a Caprice. They were only produced from about 70-75 (+/-). Pretty stinkin' scarce in junkyards, but local ads, ebay, etc. I got mine from a local Engine Shop. Damn I loved my 408 in my Nova... Glad I kept it when I sold the car

Pony Killer

destroking it is taking away the fundemental advantage of the 400 motor.. the extra cubes.

And using a 350 crank in it only lets it rev like a 350.. nothing earthshattering there...

if you want that lil sucker to rev get some biiig spacer bearings and put a small journal 302 crank in it

mw66nova

iTrader: (13)

i think that we have already determined that the statement you just made is false.

mtngeeper

Oh, a "Newbie" with an opinion.

I have a TPI 377 in my race Jeep. Sand & Mud drags. It has a 5500 rpm stall. Yes, that means you rev it up to 5501, and hold on tight! It has a balanced and blueprinted relatively expensive 400 block. (currently have two more in the garage) roller and forged everything, and it comes apart frequently. I am seriously considering putting it in a "salt flat F-body car." It has been officially dynoed at 10785 rpm's, without destruction (the valves were making funny noises.) I have the paperwork if you all want to see. 13K is a little high, but possible.

The angry rattlesnake.
Am currently building a 267 (Canadian 265) destroked with a 307 crank, some call a 254, forged & rollered, balanced & blueprinted, that will easilly hit 12K. Have been told by the old school fellas, maybe 14K?......

Then the opposite: the 307 with the 267 crank (same as a 327-350) that should be a torque monster, with good mpg's......

Pony Killer

you can think it's false.. but in reality it isn't...


fortunatly if you invest enought time and money into something and spend enough on lightweight parts... you could make it happen.. unless your trying to squeeze into a certain class it makes little sense.

ultralite parts, and or smaller journals are really the only way to get em to rev like that. for most it's not in the cards. if you wanna argue about a pink elephant... it's allright with me.. but it's pretty far in the world of whimsy.

sounds liek a pretty badass jeep. mean lil motor too as far as being a one off or darned close to it sounds like it.

tpiroc

I think the point was a 302 crank is steel and has such little stroke that in any block high rpm's are realistic due to the fact that there is less rotating mass.

unknown_host

iTrader: (1)

Why would you use a TPI setup on a motor you want to spin rpm?