Straight 6 vs V6

[SFU]

Can someone tell me what the difference is between a straight 6 and a V6. I have a vintage Ford and I have heard that the straight 6 has better torque and longer life. Can anyone comment?

[76GMC1500]

Well, a straight 6 has an enormous crankshaft (6 cylinders long while a v6 has a short crankshaft at 3 cylinders long) which works as an enormous flywheel. That enormous flywheel can store enormous amounts of energy. That enormous amount of energy means an enormous amount of torque. Most I6's have longer strokes than v6's and longer rod-stroke ratios. These also contribute to higher torque numbers.

[Don Meyer]

The old str. 6's had a fuel distribution problems as stated above. The newer ones have solved that problem w/fuel injection.

The str. 6 has a better balance(smoother running) & seems to produce more power per cu inch. Chevy has brought the str 6 & 5 back.

Thus,if you are going to install a older engine I would pick the v6, for a newer engine I would pick the str 6.

[SFU]

Thanks for the replies. So, if the straight 6 is better in all of those ways, why did car companies switch to the V6?

[Don Shillady]

Probably the V6 design was mainly due to a need for economy in terms of a sudden rise in gas prices in the '70s and to make smaller, lighter cars. I find the early odd-fire Buick V6 an interesting curiosity in which the castings for the block were literally the V8 block with two cylinders chopped off including blanking out two contacts on the distributor cap and including keeping the V8 crankshaft merely cut down. Later they redesigned the crankshaft to make the firing even at 720/6=120 degrees and with advice from Smokey Yunick the heads were greatly improved along with the intake manifold. Later the Buick Grand National model exceeded the performance of the Corvette in the late '80s, but that was after the displacement was increased. I have been fascinated by this engine, but I was convinced by the wide range of parts for the SBC350 to build a 350. Still I wonder whether the V6 is stronger at high rpm due to the short, compact crankshaft compared to the longer I6 design or even the V8 crank which may have more internal vibration? I recall Hot Rod articles on the Buick V6 claiming over 500 H.P. at higher rpm, but with so many low cost SBC V8s and the newer 4-speed automatics it is now possible to get low speed torque AND good highway mileage as with the late model Corvettes. In the realm of science fiction I chatted with an owner of a 2000 Corvette at a gas station a few days ago and he claimed he got up to 36 mpg on the highway with the 6-speed manual trans AND he claimed he had it up to 176 mph late at night on the N.J. turnpike, with the SBC V8. I find this hard to believe but the speed may be possible due to a streamlined body; the mileage is probably science fiction since reports on this forum for Corvettes have not mentioned mileage over about 28 mpg at best. Still except for less weight of the V6 compared to a V8, newer transmissions and computer controlled fuel injection have solved the problem of how to have performance as well as mileage to some extent. Then if you are looking for 60 mpg you will have to buy a hybrid car or a motorcycle. Sorry to go on and on but I did a lot of research on the Buick V6 and nearly put one in a Model-A frame and you just sort of pressed my button on V6 design. I would think that there are people on this Forum who have more experience with the Buick V6. Anybody out there own a Grand National Buick?

Don Shillady
Retired Scientist/teen rodder

[FFR428]

Don't the I 6's rev higher than the V6's? Just something I heard once...never knew the truth about it. Something like 9000 rpm's was mentioned as I recall. Don't know if it was BS or what but we were discussing the old Ford I 6's at the time. Anyone?.......G.

[FFR428]

Don I had a 86 Buick GN. With aftermarket bolt ons turbo,chip,intercooler,exaust,fuel system,cam,heads etc..... it was pushing 425hp. I tell you what though the 2 bolt mains needed a girdle for flex and it went through rod bearings on occasion. With a high stall converter that thing would hook up and run away. I never ever had so much fun with a V6 in my life. Being used to the old Ford big blocks this was a new adventure for me. I bought the car stock did a few upgrades at a time. It's an expensive toy as they all are. ATR had the best parts though Poston and Kirbans were a close second. It outran almost everything at the time. Vettes no problem.Took a while to learn how make it handle with the box body and automatic and all. Dam t-tops flexed and cracked the roof even with all the support braces in place. It loved CAM2 with a heated O2 sensor. Man that car was quick!!! I never did figure the MPG's and did not really care. The coilpack ignition system was a no brainer and overall the car was very dependable and street manners were good. From what I understand the 4.3 blocks were a little better than the 3.8's but never got that far. What a fun car and the only thing better was the GNX. G.

[lt1s10]

Originally posted by FFR428
Don't the I 6's rev higher than the V6's? Just something I heard once...never knew the truth about it. Something like 9000 rpm's was mentioned as I recall. Don't know if it was BS or what but we were discussing the old Ford I 6's at the time. Anyone?.......G.

if youer talking factory then i think its BS. i never seen a in-line 6 ford race motor turn that much eather but ive found around here you better not say anything for sure because somebody will come along and prove you wrong. 7600 in a round track car was all i could get out of a 240 before it would brake a rod.

[76GMC1500]

Apparently, you can pull a 292 out of a GM pickup without going under the truck. I was at pick and pull and saw a 292 sitting on the radiator support of a truck after somebody had pulled the engine only to find a whole about the size of a piston and shaped like a piston on its side in the oil pan. I6's have a lot of room on the sides and makes 'em real easy to fix.