8000 RPM 327? Possible?

[Guest Anonymous]

Hey guys-

 

In about 2 years, I plan on taking out a personal loan and building a nice V8 240Z. In the meantime, a complete plan of attack is my goal.

 

For an engine, I was thinking I'd like to build a high-revving 327. I want to get at least 350 HP out of it. How high can a 327 be run on a reliable street engine? 7000 or so? Maybe 8000? I know the limit will probably exist in the valvetrain, and I'm sure I'll need a nice roller valvetrain to do the job right. I'm not very familiar with extreme small block setups, and I don't know what's out there, so if anyone wants to throw together an imaginary engine (list the parts, specs, etc.) it'd be a nice start for my engine planning.

 

FYI, I also plan to either build a 4-throttle body setup, or a cross ram setup similar to the Viper's, with a Megasquirt EFI running the system.

 

The current example I plan to follow (in terms of looks, etc.) is Pete Paraska's car. What a beautiful machine! I want to run a BW T5 tranny (cost issues), and I don't want a monster of an engine; a high revving 327 will be plenty of power for a 2500-pound car! I want to fit tires under the stock fenders too. I don't want to end up with a bodywork nightmare, so I'll make sure my starter car (which I don't have yet) has a straight and relatively rust-free body.

 

Thanks for any input... hopefully this will turn into a debate on how to build a high-revving engine... that'd be awesome.

 

-Rodney

[Scottie-GNZ]

Robert,

 

I am sure this group will debate it to death, but IMO, "reliable, street engine" and 8000 RPMs sounds like a contradiction. Just curious, why the obsession with high-RPMS when torque is what rules on the street. MOF, my question itself will probably start a debate

 

Oh yeah, WELCOME.

[mobythevan]

If torque was the "only"thing that mattered, then everyone would stick a diesel in their car. Then you could have like 2000lb/ft of torque. Isn't it actually the highest torwue at the highest rpm that is most desirable? I guess everything is a trade off. For torque at low rpm you need gearing to take advantage of it. Discuss on...

[Mike C]

It is VERY easy to get 350hp from a 327 at 6200 rpm. Why spin it to 8000 unless you hope to get 500 hp? If money is an object (and you state that it is)just get a small journal 327, add forged flat tops along with a set of Vortec heads. Rebbuild the stock rods adding ARP bolts and have the entire assembly balanced. Add a Comp 282S solid lifter cam and you shoule EASILY get 350 horses at 6000 rpm. THis should be less than $2000 including an intake. The lightweight recip assembly and careful assembly to survive 8000 rpm will cost more than the complete buildup of the 6000 rpm motor. I have a 4 bolt main 327 in my Jimmy. Used to be in my Camaro. It is a 4 bolt 350 block, large journal 327 crank with 186 heads and TRW 4 valve relief flat tops. It has over 100k miles on it now and still runs quite well. With a Crane 284 cam, it pulled hard to 6500 rpm and ran 14.10 in my 3500# car with a 2800 rpm converter and 4.11 gears. It has a smaller cam (crane 266) now that it is in my truck, and I would bet money it would be faster in the car than it was with the big stick. Listen to the guys talk about torque, but my opinion is to maximize torque while building a rev range similar to the L motor for a Z. 1000-6000 rpm driveability.

[Guest Anonymous]

Thanks for the input, guys!

 

I know about the whole torque vs. high revs debate... I used to have a Honda del Sol VTEC with the 8250-rpm 1.6 in it, and even though it only has 111 lb-ft of torque, it stomps on many other sport compacts.

 

I've found that in the end, what matters is the area under the torque curve. A long, low torque curve will work very well, and a tall narrow torque curve will work too. Although any 327 will have more torque than any car I've ever owned, I know it has less torque than a 350 or a 400 would. Therefore, I don't want to build something that runs out of breath at 4500 or 5000 RPM. I'd like it to spin fast and have a long powerband, so I can get the most out of the motor, within reason. If I want something

 

If I can get well over 350 HP at around 6000 RPM, that's cool with me. Money IS an object. I want to put alot into the suspension and the interior.

 

Mike C, thanks for the specs... that's the kind of info that will really help me! Also, I'd really be interested in seeing some dyno pulls from an engine similar to what I'm looking to put together. If anyone has some, please holler...

 

-Rodney

[Guest eric-z]

well I'm not the most knowledgeable guy on the site but you might consider building a 302. I think you use a 289ci crank (plus spacer because of larger journal) with the 350 block(4.000bore x 3.00stroke). I think those could push out 375hp if built right. I've read some about this combo and supposidly it revs a bunch. I don't know how much it would cost you though. chevy made this engine stock in late 60's early 70's and used them in the z28, I believe. I think it was for trans am raceing or something like that. you probably wont find a stock 302 but thought you might like to know so could check it out if you wanted.

eric

[Guest Anonymous]

building an 8000 rpm 327 isn't a problem , but reliability, driveability, and street ability could be. If you want 8000 youll have to be running a solid lifter cam, you cant do it with a hydraulic cam, not on the street anyway, but you can go 7000 reliably with hydraulic cam, but everything has to be perfect. A nice set of heads always helps too.

[blueovalz]

I love the Freudian slip here. Yes-sir-ee-bob, the Ford 289 was a real fine engine. Anyway, I say go for it. My 289 (not a 283 guys, sorry) has seen 8k one time since the rebuild, and lots of 7k+, and yeah, it's kinda high strung, but you got to love it when you stay in gear while the other guy is shifting already. Will it win a race, maybe not, but the RRRRR's are part of what this hobby is all about. "Tach it up, tach it up, buddy gonna shut you down".

[Mudge]

To make 350 HP out of a 327, you do NOT need to rev to 8000. I dont see why you'd have a problem reaching that though, with cast crank/pistons with a roller cam I've seen 7k (factory engine). Likewise at those RPM levels I'd probably go with a solid roller, which means yet again more cost, and plenty more than 350 HP.

[Guest Anonymous]

going along with Eric's idea (i think), there is a chevy DZ302 here for $850. not sure of the condition, but these motors were rated at 290hp for insurance reasons- but with a set of headers and a higher lift cam they have been rumored to pull near 400hp. i can get you a number if you are interested. i'm in NC.

[RPMS]

Sure, torque is what wins races, but the real charge (for me, anyway) is the whole package deal of going fast. When a car can combine acceleration, handling, comfort, and makes the "right" sort of noises under acceleration, THAT is slick! And the "right" sound (for me, at least) occurs somewhere above 6,000 RPM. Winding a powerful motor up to the stratosphere carries with it a profound sense of gratification. The sounds that the GT40 replica makes David Karey's Post is an example of what I consider to be the perfect car noise. Listening to that man wind his car up through the gears is just about enough to make me want a cigarette.

 

I say, go for it! Spend the extra money to make an engine that will scream up to 8k rpm and make your local ricers scatter in fear!

[SpeedRacer]

I'd vote for the 302 CID SBC as well. Thanks to the TransAm series a 302 in the race Z28 (every part had to have a factory part number!) produced 465+ HP at 7,800 back in the early 70's.

 

I think all but the first Z28's used large journal nodular iron cranks. The last time I checked one of these cranks was going for $1,400 used! Since that may drive up the price the 327 would be the next logical choice.

[grumpyvette]

first read this

http://www.69mustang.com/hp_torque.htm

 

http://www.carcraft.com/editorial/article.jsp?id=868

 

http://home.att.net/~jroal/perftheory.htm#Basics2

 

http://www.howstuffworks.com/horsepower2.htm

 

keep in mind that stress is cumulative, stress squares when rpms double, in other words a 327 spinning 3500rpm compared to a 327 spinning 7000rpm does not have twice the stress but more than 4 times the stress. also keep in mind that EACH CUBIC INCH OF DISPLACEMENT normally makes about 1.2hp in a well built engine now given those facts its not a large streach to see that a 406 spinning only 6400rpm has LESS stress, potentially makes far more hp and lasts longer given that a 327 would need to spin about 7400rpm to make about the same hp per cubic inch yet would be very hard pressed to make nearly the torque or hp at any rpms

[Guest Anonymous]

If you are looking at a dream higher rpm SBC, why not a 377 (400 block and 350 crank)? Forged 350 cranks are easier to find than the old 302 crank and there are special thick main bearings to make up for the difference in the main diameters.

[Mudge]

The GT40 example is a bad bad bad example. Sorry, but that car made less than my daily driver, 450 HP out of a 350 Chevy is not a high winder by any means at all.

 

Torque will power you out of corners, if your doing straight line only (Silver State Classic), then I'd consider still a torquey engine. I know a guy who built a torque monster for this VERY reason, 4000 RPM L98 (422 cube???) stroker, solid roller, the works, all built for low RPM duty at over 200 MPH. I never thought if it like that myself until I ran into him, but he is right on the money, low RPM is mo betta for long lasting fun, and in enduro you need that.

[Guest Anonymous]

I always thought a 302 SBC was a 327 block with a 283 crank and some long rods.Its a good thing I have a 406,Who knows what I would have ended up with.

[Mike C]

All first gen small blocks except the 400 have 5.7" rods. The 67 302 was a 4.00" 327 small journal block and 3.00" steel crank. While it is possible to build a 302 with the 283 steel crank, the counterweights are different and require more time on the balancer. The 68 was a large journal 2 bolt main motor while the 69 was a large journal 4 bolt. All had STEEL cranks. 290 hp WAS an accurate hp rating for the motors, at least at 5000 rpm where they rated it instead of its 7000 + rpm power peak, so you can see how peaky the motor was. THe secret to making power in the 4" bore blocks (302/327/350)are the big valve 2.02/1.6 cylinder heads, either GM or aftermarket. With virtually the same cylinder heads and a similar cam, a 70 LT-1 will blow the doors of a first gen Z/28 in a drag race. HP is about the same, power peak is a little lower, but all that torque... I am in complete agreement that a 302 is an awesome Z motor, but dollar per dollar a 350 is the way to go. Or if you already have the 327, a motor similar to the 350hp L-79. I am in complete agreement with Grumpy on stress to the motor but would like to add the fact that the longer stroke imparts more stress than the shorter one at the same rpm, both on the reciprocating assembly and because of the high piston speed relative to the shorter stroke at same rpm.

[Scottie-GNZ]

If torque was the "only"thing that mattered, then everyone would stick a diesel in their car.

That is taking my comment a little out of context, isn't it?

 

Heed Grumpy's warning. I do believe money is a factor here so remember that the cost of HP is cheap relative to the cost of reliability.

[pparaska]

Thanks for the comps on my car, Rodney!

 

I have the 327, it's only a tiny bit high strung (not alot of torque until the upper 2000 rpm range) and as you might have read, I'm going to a 406. Why? More low end torque. I could put a milder cam in the 327 to get some more, but it wouldn't be much more.

 

After driving the car several thousand miles, I've decided that one of the things it DOESN'T do well is cruise down the road well at a comfortable rpm. By that I mean 5th is just for cruising, not really for any kind of acceleration you'd associate with a V8 Z. I know, don't tell me, just put it in 4th. I find myself cruising in 4th mostly, but the engine's at 3000+ rpm at that point. What's the point of having OD, if you don't use it?

 

To me, Mike C really has the right idea for what I want in a street engine - 1000-6000 rpm drivability. (Well, 1500-6000 might be just fine ).

 

Also, finding cranks, bearings in .001 undersize, etc. became a problem for me when I went through my 327 a year ago. The stuff was more expensive as well. A 350 will turn 6500 rpm with a low cost parts and give more torque across the power band and of course, that means more power too. I'm spending a bit more on 400 parts than 350 parts, but that's because I really want that high, flat torque curve from 1500-6000 rpm. 390+ foot pounds from 2000-5500 rpm is gong to be SO MUCH more impressive to drive around than the higher strung 327.

 

Just passing on my experiences.

[Guest Anonymous]

Hmm... If I can get the revs I want out of a 350, maybe I'll just take advantage of the lower cost of parts, higher torque, etc. and go with a 350. One thing I'm worrying about is overloading the T5 I intend to put behind the 350... I guess I'll just start looking around for T5's and T56's, and see if I can get my hands on a reasonably priced T56. I wanted to keep my torque relatively low and my revs high so I could stay in a T5. Given 255 rear tires (like Pete's setup), what is a reasonable estimate of the maximum engine torque I could safely expose a T5 to? Isn't it around 350 lb-ft?

 

-Rodney