327 or 350?

[Guest Crema240z]

1971 Datsun 240Z

 

What is a better swap? 327 small block or a 350

 

Im new to this but ive heard things about the 327 like it has a better compression ratio than the 350 and it runs better on pump gas. They can also push around the same hp completly stock

 

but why do people do 350 swaps??

 

remember i am new to this please help me out

[Confused]

I would go with the 327. I dont know for sure, but I think people do 350 swaps, because its a motor that is not uncommon to find for "cheap".

[wheelman]

Welcome to the board.

Be sure to use the search function, you'll be able to answer just about any question you can think of.

 

More 350s are swapped because they are so common and cheap that it's nearly impossible to beat them from a price stand point. That having been said the 327 will make a swap that is a little bit more unique. You'll also hear that the 327 can rev higher than the 350 but this isn't really true in a strict sense as both need to have the valve train upgraded and then will have virtually identical red-lines. So from a price and availability stand point the 350 is a better choice, but everyone has one.

 

The higher compression ratio of the 327 is only because of when it was built (read very high octane gas) vs most 350s (read lower octane gas and added emissions stuff). Get a late model LT1 and you'll have either 10:1 or 10.5:1 depending on what car it came out of.

 

What are you planning to use the car for? The intended application should be considered when deciding which engine to use. Drag racing would probably benefit more from the extra torque of the 350 with an auto tranny while road-racing/AutoX might be better with the 327 and a 5-speed.

 

I've got a fuel injected 350 (LT1) in mine with a light flywheel and a 5-speed tranny and it revs to redline (6300 rpm) very fast. As I was building it I thought alot about how different it was going to be from the L6 as far as revving to redline and I have to say it "feels" as revvy as the L6. Starts making power at about 2000 RPM and pulls hard through 6000 with a very flat torque curve, but thats because I swapped out the cam for a little bigger one.

 

Wheelman

[280zwitha383]

If you are rebuilding both engines, with a 327 you can run a little higher compression than you could with a 350 because the 327 has a shorter stroke. I would argue that the benefit of running higher compression with the 327 would at best be equal to the extra cubes and longer stroke of the 350. I think a 350 is the best choice for both performance and cost.

[Pyro]

A 350 will make more power than a 327 if all the same stuff is used. Why give up power?

 

It is harder to build compression with a 327 due to the smaller displacement. Dome pistons must be used to get over 9:1 on a 327 with todays smallest combustion chambered high performance heads. Todays high performance aftermarket is aimed at 350 and larger engines.

 

It is like building a 2.6 liter instead of a 2.8 liter, why would you want to do that for. More cubes, more power

 

My 350 pulls hard to 7,000 rpm.

[pparaska]

I'd build a 383 or a 400, personally. I've done the 327. Nice engine, but I wanted more grunt, along with a less radical character, so I went with a 400. I'm making other upgrades to the engine besides displacement, but I saw staying at 327 ci as leaving too many cubes on the table!

 

You don't need to rev high if the gearing and powerband are designed to do what you need! High revs cost because of the expensive valvetrain needed.

[Guest 305240]

If you can score a good 327, by all means do it. Who says you have to run 350's in everything? Be different! I've got access to a good 283. In my book, that would make a great Z engine for the street.

[jack46]

Well which are better to date blonde or brunette? No right or wrong answer, it is a personal choice. I would start by determining what you want, and how much you want to spend. udget is ALWAYS more than estimates.

 

If you want to be unique, fast, or whatever is your criteria go for it. In the end you will have to live with it. Just be as realistic and honest as possible with what you want.

 

Good luck

 

PS I had a 305 Z for ~15 years and loved it. Was a daily driver and was fine until I got the racing bug. Then converted to 383 then LT1. That is also a MAJOR consideration more power more breakage and problems.

[Zerrari GTO]

I've done the 327. Nice engine, but I wanted more grunt, along with a less radical character, so I went with a 400.

 

Pete, what do mean by "radical character"? I want a 327 for my car because it would seemingly have a little revier sound that would be better suited for the 250GTO body.

 

I want average compression 9:1 and moderate H.P. (around 300) using as mild of a cam as possible. I have a T-5 WC and thought this type of engine would help keep me out of the transmission shop.

 

I'm not sure how radical your 327 was but what I want is a very easy to deal with engine-not with radical character.

 

Is the 327 a good platform for this?

[pparaska]

It was the cam that made it radical. Comp Cams Xtreme mechanical flat tappet, 12-677-4 (CS274S-10), 274/280@.015", 236/242@.050", .501/.510" lift, 110 LSA. The rest of the details on the engine are here (Scroll down for the 327 info): http://alteredz.com/EngineInfo.htm

 

About 12-14 inHg vacuum at 900 rpm idle. low speed torque was moderate. Throttle response o.k., but only with a well tuned small carb or EFI. The small carb severely limited top end power and punch.

 

But (on my 327 build) I was shooting for the most power I could get while being "streetable". The 110mph trap speed means probably about 375hp at the crank.

 

For me, NA is the only way. N2O is not really valid for me on the street. Turbo and supercharging too expensive and complicated for my liking.

 

So to get the kind of peak power and powerband I wanted, I decided to go for CUBIC INCHES. With a fairly mild solid roller to maximize lift and area under the lift/duration curve, along with good flowing heads. DD2000 says over 500hp/lbft in the various combinations of headers and intakes that I'll run through as I modify things.

 

My feeling is that if you want a mild engine that still has plenty of thrust, leaving cubes on the table is NOT the way to go. Even with the ~375 hp my 327 had, I was wanting MORE THRUST!

 

A mild 327 would bore me in no time, even in a light car like a Z.

 

Oh, don't get caught up in that old "327s rev so much quicker" nonsense. Maybe without a load. More torque from a longer stroke (and bore) will accelerate the car faster. The only thing you gain with the shorter stroke is a higher allowed rpm in terms of piston speed and maybe some detonation resistance.

 

JMO

[Guest traub83]

327's are great motors, and 350's are well 350's you can buy parts everywhere for umm.

 

If ya want to be different id build the 327 personally do a mild buildup decent heads and you will have exactly what ya want. you can do the same with a 350 tho it just depends on you man...

 

I have a 350 I built for my Z and who knows when I will get my Z ready for the motor but I have a 350 4 bolt block, stroked out to a 383, holly systemax II system on it all ported and polished, 1.6 ratio rockers, Eagle steel crank H beam rods and JE forged pistons, im about 8.7:1 compression, I have not bought a carb for it yet cause im investigating which would be best for my setup since I purchased the Vortech Supercharger for my motor also. My engine s way more than enough for my car and i only built it for looks and just something to tinker with. I am by no means going to be racing my car everyday or much at all.

 

My car when all is said and done will have no gas mileage I know but thats what I built it for. For you if you want a lil more umph just rebuild that 327 motor ya know freshen it up, throw a small cam in and headers and call it a finished project. you will get decent mileage and your Z will fly. 300hp in one of these cars is a lot trust me ya will have no problem with most street cars if ya want to race them. Im just saying be practical think things out for exactly what you want your car to do and go from there.. regardless it sounds like it will be a fun car to have...Good Luck and i hope i didnt blabber around too much!! =)

[SHO-Z]

Use the 327 block and put a 283 crank and build a 302 like the 60s Z28 had in them. High rever and lots of power. The only problem is they are expensive to build, piston cost.

[Guest traub83]

Use the 327 block and put a 283 crank and build a 302 like the 60s Z28 had in them. High rever and lots of power. The only problem is they are expensive to build, piston cost.

 

Very Tough motor tho, personally I like that idea a lot cause I bet there are not many Z's around with a 302 chevy in them!!

[280zwitha383]

A 302 Chevy that makes a lot of power huh....... Why not just put a Ford 302 in it, I hear they make a lot of power too

[Guest traub83]

 

apples vs oranges ya say?? a 302 chevy engine is a good motor same as a 302 ford, he is wanting something different makes a decent amount of power not a million horse. why not do a 302 chevy? it is different, it can make good power, and it would be easy to build. but for what he wants id just build a mild 327 and call it a day. just keep what ya got and go from there dont go messin around with strokes and that just for a good running motor that ya don't plan to race. just rebuild it stock like throw a decient cam in chome paint it out so it looks good and boom cheap and fun.. JMO tho..

[280zwitha383]

Don't get me wrong, I'm not against putting a 327 in a Z at all. I would love to build my wife one with a t-56 because I think it would be really fun to drive (the only reason I wouldn't build up a 350 or 383 for her is because she's a woman.... need I say more?). On the other hand, destroking a 327 would not only be expensive it wouldn't be practical. You would have to purchase mismatched parts and I would assume have them balanced all to give you less cubes and less power. It just doesn't make sense to me.

[Guest traub83]

Don't get me wrong, I'm not against putting a 327 in a Z at all. I would love to build my wife one with a t-56 because I think it would be really fun to drive (the only reason I wouldn't build up a 350 or 383 for her is because she's a woman.... need I say more?). On the other hand, destroking a 327 would not only be expensive it wouldn't be practical. You would have to purchase mismatched parts and I would assume have them balanced all to give you less cubes and less power. It just doesn't make sense to me.

 

My point exactly also.. the 302 is a great motor but your right it would be more expensive to set one up rather than what he already has. expecially when a 327 is itself a great motor, dude just rebuild freshen up that 327 throw a decent cam in and you will have a 300hp motor id bet and if not it be darn close, and regardless it would run like a champ. I really dont see how ya could go wrong with any motor if there built right personally, ok a briggs and straton 5hp is not what I ment also ha ha just to clear that up before someone trys some funny bussiness lol...

Peace all and good luck on your choice and car bro

 

after reading this again i need to state some more small things, less cubes dont always mean less power? a 383 should have more torque than a engine with less stroke however it dont mean its the faster motor in regards to many small blocks.. a 327 motor can build just as much power as a 383 can.. its just blueprinting and building the motor to do what you want it to do. thats all. now the old sayin i also believe there is no replacement for displacement i believe that to be fairly true but its not always so. take for instance the 3.0L skyline RB30 motor its a lot smaller than a 350 in fact the 350 has 2 more pistons than the rb motor, now the rb is turbo'd but it can make crazy HP numbers that will rival a turbo/supercharged 350 see what I mean? its not all on how big the motor is its how its built that counts.. I hope i didnt open a can of worms here but if i did im sorry im just defending the smaller cid motors in the world!!

[grumpyvette]

after reading thru this thread I think some of you are missing a few points

 

the least expensive combo to to build with the most hp per dollar spent will be a 350 with a solid lifter cam and a decent set of 195-215cc heads

 

I build these all the time, and a similar 383-396 sbc only costs a few hundred dollars more, so most guys opt for the 383-396 sbc simply because you get approximately the same HORSE POWER PER CUBIC inch of displacement, keep in mind that,HORSE POWER PER CUBIC inch of displacement,(thats average not peak hp, both engines may peak at similar hp but wont be close on average tq)because a 383-396 has three major advantages, first obviously the extra 33-46 inches of displacement are obvious, but the other two factors are not, that increased compression with the same cam timing and combustion chamber size and that the longer stroke lowers the EFFECTIVE RPM BAND, this tends to make controlling the valve train far easier in the upper rpms , while a 350 normally operates up to about 7000rpm, a 383-or 396 tends to operate at its peak of about 600rpm lower, at about 6400rpm

 

lets look at the differance because its important

 

lets use the same cam ,a crane 110921 heads,ARF210cc and start with a 355 with 10.5:1 cpr useing flat top pistons and a single plane intake with a 850 carb and the DD-2000 makes its wild guess at

511hp/456tq

now lets build a very similar 383 using all the same components

 

we find HORSEPOWER peaks at a similar 518hp but drops 500rpm and your up to 10.9:1 cpr and you gained tq to 484 ft lbs now that does not appear to be a huge gain UNTILL you look closely at the TQ curve the longer stroke increased AVERAGE tq about 35-37 ft lbs over most of the curve,and your port air flow velocities with the larger displacement tends to give you a more efficient cylinder fill(volumetric efficiency)and CYLINDER SCAVAGING from the exhaust

 

BTW that similar 302, would require smaller head ports, and would make good hp at just under 500, but would be about a 100 ft lbs lowe in tq that the 383, thats A HUGE DIFFERANCE in its ability to move the car, and controling the valve train at 7500rpm PLUS can be a problem

[pparaska]

Here's a 350 like grumpyvette spec'd (w/ large tube headers with mufflers):

 

rpm___HP___ft-lb

4000__321__421

4500__378__441

5000__429__450

5500__466__445

6000__487__426

6500__501__405

7000__493__370

 

Here's a 383 with the same parts (last two columns show the change in hp and ft-lbs from the 355):

(updated - I forgot to bump the comp ratio to 10.9 from 10.5 before)

rpm___HP___ft-lb__dHP__dft-lb

4000__347__456___26___35

4500__404__472___26___31

5000__454__476___25___26

5500__487__465___21___20

6000__503__440___16___14

6500__509__411____8____6

7000__493__369____0___-1

 

Look at torque or horsepower under either curve. I'll take the cubes and more power and torque any day. No need to rev beyond 6500 with the 383, and doing so means less longevity. Like Grumpy said, you can use cheaper valvetrain parts if you stay below 7000 anyway.

 

Some food for thought: The people who experienced the old Z/28 Camaro's on the street with the 302 talk about how UNstreetable they were compared to the larger 327 or 350's of the day. That higher power band gives away the "mild" nature that crema240Z said he was looking for. To make power with the smaller engine, you need to rev higher, granted. But with that comes the more radical cam profile (all else the same). And the attendent valvetrain issues and costs. So if you want the high winder for some visceral reason, realize that if you put time on the engine at those elevated rpm levels, the valvetrain will become and issue.

 

To shed some numbers on grumpyvette's last comment on the 302 with smaller heads (AFR 195 Competition ported) (but same cam):

 

rpm___HP___ft-lb

4000__277__364

4500__333__388

5000__384__404

5500__426__407

6000__456__399

6500__479__387

7000__484__363

7500__483__338

 

Okay, here are the graphs - easier to see. Like grumpyvette has mentioned before, DD2000 is optimistic below 4000, so don't look to close to that area and below.

 

 

Why install an engine that weighs exactly the same but has 100 ft lbs less than the 383 (the 302), is more expensive to build, is harder on parts and less streetable? The only answer must be the desire for mystique (doesn't a V8Z already have that, I have to ask?) or a desire to be really different (nothing wrong with that) or because you like a peaky engine that can rev higher (again, nothing wrong with that). Just make sure you go into the decision looking at what performance you'll be losing, (not to mention added cost and reliabilty) .

 

I have a wiped flat tappet cam I just pulled out of my 327. I was pushing that engine somewhat hard with a fast acting cam - the reliability of the valve train caught up to me after 10000 miles. A more mild cam would have lasted longer, I'd think, but left performance lower (which I didn't want - heck, the 327 was getting boring with the power level it'd had).