327 vs 350

[codyethridge]

Hi,

 

I have a two part question for the V8 SMEs (subject matter experts). First I have to provide the background info and my goals. Background: the car came with a stock (maybe slightly better heads) SBC 400, T5, and R200. The engine if I understand correctly was pushing 200-225 HP and around 300 lbs of torque. Due to the size of the tires (small) it would spin on 1st-3rd gear, so not too worried about the transmission at this time. Currently the car has been stripped down and media blasted. It needs a little work on the body in the usual places. The frame rails and body has been stiffened as well as a 6 point cage added. I paid too much for the car, but such is life. Goals: I'm in the military and hope to be station in Germany, so with that in mind I want a top end car. I'm not interested in drag racing it, but once or twice to see what it'll do. I might road race it if I have the time. I'd like to have a high RPM engine (top end in mind), with good HP and not huge amounts of torque. As an example say 375 HP with 300 lbs of torque. So as the 400 SBC is a high torque engine it is out as an option. As I have motor mounts for a SBC please don’t list the RB26 or any of the others. Also I don’t have a huge budget as the rest of the car will require a lot of work.

 

Questions:

 

1) Which engine is a better fit for what I wish (high RPM engine (top end in mind), with good HP and not huge amounts of torque) a 327 or 350?

 

2) What cam would I need in either to get this? (high RPM, high HP and not huge amounts of torque)

 

Thanks for your time.

[emeraldlion]

I would look up member Bjhines and view his build, not just because it is an incredible hybrid sbc v8z, but because he is using the 327. I think this is probably the route you should go. I have a 283 right now but I have a feeling I will be upgrading to the 327 not too long after I have her running. I picked up the 283 really cheap. I too have similar goals in mind. My car does not have the bracing that lot have, and while it won't be seeing any heavy racing, I don't want to build large torque numbers low. I also like the short stroke motors(I think the have a unique sound). Whatever route you go, keep us informed.

[rsicard]

Hi,

 

I have a two part question for the V8 SMEs (subject matter experts). First I have to provide the background info and my goals. Background: the car came with a stock (maybe slightly better heads) SBC 400, T5, and R200. The engine if I understand correctly was pushing 200-225 HP and around 300 lbs of torque. Due to the size of the tires (small) it would spin on 1st-3rd gear, so not too worried about the transmission at this time. Currently the car has been stripped down and media blasted. It needs a little work on the body in the usual places. The frame rails and body has been stiffened as well as a 6 point cage added. I paid too much for the car, but such is life. Goals: I'm in the military and hope to be station in Germany, so with that in mind I want a top end car. I'm not interested in drag racing it, but once or twice to see what it'll do. I might road race it if I have the time. I'd like to have a high RPM engine (top end in mind), with good HP and not huge amounts of torque. As an example say 375 HP with 300 lbs of torque. So as the 400 SBC is a high torque engine it is out as an option. As I have motor mounts for a SBC please don’t list the RB26 or any of the others. Also I don’t have a huge budget as the rest of the car will require a lot of work.

 

Questions:

 

1) Which engine is a better fit for what I wish (high RPM engine (top end in mind), with good HP and not huge amounts of torque) a 327 or 350?

 

2) What cam would I need in either to get this? (high RPM, high HP and not huge amounts of torque)

 

Thanks for your time.

 

Cody:

 

Retain the 400 block complete. The 327 will be costly to purchase. Buy a good 350 4 bolt main single piece rear seal block, bore it .030" put a SCAT 3.48" stroke forged crank. 6.125" SCAT forged I beam rods, SRP Professional pistons which are only 376 grams each (very light weight forged) for the bottom end. For the top end AFR-195 competition cylinder heads, an appropriate camshaft and good intake manifold and carb. The camshaft should be solid roller type, solid roller lifters and Comp Cams thick wall push-rods and 1.6 ratio rockers. The camshaft will be the most important as to where in the RPM range the peak horsepower and peak torque occur. With the camshaft solid rollers a more aggressive lift camshaft can be used and 7000 to 8000 RPM is doable. This camshaft can be such that the 350 will be somewhat mild below 5000 RPM and come on VERY strong above same, aka 327 like. Good around town and very good at the track.

 

I am in Tucson also and have built a stroked 350 similar to that described above. Can recommend suppliers and local machine shops.

[Michael]

First, be especially mindful of German car registration requirements, if your objective is to enjoy this car in Autobahn driving while stationed in Germany. I hear from an acquaintance who now works for Siemens in Germany, that registering a modified Datsun would not be an easy undertaking; much harder than say in California or other US locales known for automotive stringency. They have their own rules on roll cage design, bumper height , and many other factors. If you already have friends stationed in Germany, ask them about car registration and whether they were able to secure any sort of exemptions owing to their military status.

 

Second, the lack of torque is not by itself an advantage, even for a high-rpm engine. Instead what happens is that an engine producing high volumetric efficiency at high rpm ends up being comparatively weak in low-rpm torque, because it has poor volumetric efficiency down there. It is self-defeating to intentionally reduce displacement in an attempt to bias in favor of high rpm power.

 

Before you receive a barrage of links to books and web sites describing suggested builds, just consider the two main ingredients: the engine should breathe well at high rpm (carb, intake, valvetrain, heads, exhaust) and the rotating assembly (crank, rods, pistons, valvetrain) should remain robust at high rpm. That’s it. It’s not about rod-to-stroke ratio or bore-to-stroke-ratio or whatnot.

 

Also note the gearing (tire diameter, rear axle ratio, transmission ratios) and what rpm range your desired cruising speed will place you. With a tall 5th gear (0.6 or whatnot) and a 3.54 rear, you may find that 7000 rpm is completely unnecessary.

 

From my forays on Autobahns mostly in central Germany (general area from Darmstadt to Bonn and the Ruhr and west, up to Bremen, over to Braunschweig), it is quite rare to find an unlimited spot where you can buzz past around 240 kph; there’s too much traffic and too many curves in the road. Most “unlimited†stretches only allow getting up to around 200 kph before the next speed-limit warning sign looms ahead. There are a few satisfyingly wide, flat and comparatively empty stretches, such as south of Frankfurt airport, heading towards Darmstadt. But that’s only around 20 miles. So in reality, German vs. American driving (especially in Arizona) would not be tremendously different.

[codyethridge]

Thanks everyone for the inputs so far.

 

riscard: that is just what I'm looking for and will start doing the research. What if I can get a reasonable 327 ($2100 fully put together)? Would you still get the 350?

 

Michael: You are correct in that US military have exemptions. I'm in the US military and have been stationed there twice (total of 5 years). All the car has to pass is safety test and lights, etc. I had two Nissan Skylines (GTS wished GTRs) shipped from Japan and drove them in Germany. Both sucked due to gear ratio, but that is another story. There is some awesome stretches of road in the former East Germany. You cannot compare the speed you can do in GE to AZ. I cruised 90-100 MPH in our Pathfinder. I got up to 150 MPH in a Audi Quattro TT. That was a blast. Overall you're right that it is hard to find a stretch that you can do 150+ MPH, but you can. AZ you do that speed and they'll take your car from you and you'll end up in jail.

 

I do want torque just not massive amounts of it like the 400 SBC has. Something reasonable as I'm not interested in going fast down a short stretch of road (drag racing). Maybe a 1 to 1 ratio? The gearing is something I've got to research as well. I'm not sure what I have right now.

 

Thanks again everyone.

[Leon]

Michael put it very well, so I don't find it necessary to repeat all he said. You do want massive amount of torque (why wouldn't you?), just at a higher rpm.

[rsicard]

Thanks everyone for the inputs so far.

 

riscard: that is just what I'm looking for and will start doing the research. What if I can get a reasonable 327 ($2100 fully put together)? Would you still get the 350?

 

Michael: You are correct in that US military have exemptions. I'm in the US military and have been stationed there twice (total of 5 years). All the car has to pass is safety test and lights, etc. I had two Nissan Skylines (GTS wished GTRs) shipped from Japan and drove them in Germany. Both sucked due to gear ratio, but that is another story. There is some awesome stretches of road in the former East Germany. You cannot compare the speed you can do in GE to AZ. I cruised 90-100 MPH in our Pathfinder. I got up to 150 MPH in a Audi Quattro TT. That was a blast. Overall you're right that it is hard to find a stretch that you can do 150+ MPH, but you can. AZ you do that speed and they'll take your car from you and you'll end up in jail.

 

I do want torque just not massive amounts of it like the 400 SBC has. Something reasonable as I'm not interested in going fast down a short stretch of road (drag racing). Maybe a 1 to 1 ratio? The gearing is something I've got to research as well. I'm not sure what I have right now.

 

Thanks again everyone.

 

 

codyethridge :

 

Aside the issue of driving in Germany, finding a good 327 is getting difficult as they are much fewer in number than the 350. The same objectives can be achieved with the 350 and they are MUCH more plentiful and therefore CHEAPER and so are the parts for same. The reason for recommending the SRP professional pistons is their design, light weight and strength. With 6" rods the piston becomes lighter. Then the rotating assembly can be INTERNALLY balanced. Neutral balanced flywheel and front damper can be used. When it comes to dampers use the fluid dampers as they are the MOST effective.

 

Yes this is the more expensive path, but the results can be BULLET proof and every bit as effective as Gen III and IV small blocks. The cylinder heads, camshaft and intake dictate efficiency of the engine. Admittedly when designed for most power at 5000+ RPM, efficiency will be less at lower RPMs. This can be fixed by a less aggressive camshaft. By putting a 2 piece timing cover on making it much easier to swap out camshafts. Best to use a camshaft gear drive as their will be MUCH more accurate cam and distributor timing (less spark scatter) over the life of the engine. The SMALL down side is extra noise from the gear drive. With lighter weight reciprocating bottom end the engine will wind up quicker. When doing a 350 doing it right the first time yields more than satisfactory results. Doing it a second time is much more expensive. You decide.

 

These recommendations come from experience and extensive reading of David Vizard's books and Internet posts. Next to Smokey Yunick (Deceased), David Vizard is an expert on Engine Building. Look these two guys up and you will find a wealth of knowledge regarding engine builds.

[Pyro]

I say, stay with the 400.

 

http://www.chevyhiperformance.com/techarticles/148_0401_chevrolet_406_ci_engine_build/index.html

 

or build a 350. easy to build a 7000 rpm 350. nothing special required to make a 350 sing: proper part (heads, forged crank, balanced, valve springs, cam, and rod bolts) and a 350 will rev like crazy.

 

327 is a worthless engine with a cool name. imo. Why spend more money on a 327 that makes less power than a 350??