V8 Debate

[Profpointy]

V8s smooth? Cross plane V8s require ballancing weights, and flat plane a couple of balancing shafts. Straight 6s (and V12s) offer fundamental smoothness. Which is why our train diesel engines are mostly based on 6 cylinders (6, 12, 18, etc).

Whilst I've never owned a V8 I have driven a couple but agree that straight sixes seem a lot smoother, and I understand that is the fact of it too. My own straight six was a very basic, almost agricultural, pushrod 2litre on my Triumph Vitesse, it it was silky smooth. I'm sure a Jag or Merc straight six would be even nicer

 

[raleighnut]

Whilst I've never owned a V8 I have driven a couple but agree that straight sixes seem a lot smoother, and I understand that is the fact of it too. My own straight six was a very basic, almost agricultural, pushrod 2litre on my Triumph Vitesse, it it was silky smooth. I'm sure a Jag or Merc straight six would be even nicer

The Jag straight 6 was good in 2.4 or 3.8 versions but the 4.2 suffered with the block flexing and didn't rev as high, more suited to the automatic gearbox in the 'luxury' models with it's increased torque.

 

[Profpointy]

The Jag straight 6 was good in 2.4 or 3.8 versions but the 4.2 suffered with the block flexing and didn't rev as high, more suited to the automatic gearbox in the 'luxury' models with it's increased torque.

A 60s Jag is plausibly on my shopping list at some point; likely the S-type as it'd be younger and cheaper than the Mk2. The Mk 2 is itself half the price of an XK150 or E type too

 

[rogerzilla]

A 6 is indeed smooth, but it becomes impractical above certain sizes and rpm, and its length is also an issue.

I'm not sure about the train engine point. They generally go in 4s (as you'd expect) so V8s, V12s and especially V16s (various generations of the English Electric V16 powered British diesels from the LMS twins up to the Class 50) are really common. The recent rather lovely, if noisy, Class 68 uses a Caterpillar V16.

The most prolific main line diesel, the Class 47, used a Sulzer H12 (two straight 6s in one casing, geared together*) just to be different. The small Class 48 was the same thing with a V12, but it turned out to be terrible.

*also rather heavy, with two crankshafts and an output shaft

 

[T4tomo]

I had a an old late 1990s Volvo V90 that was 3.0 straight 6. No turbo, 'only' 200bhp but buttery smooth and enough torque and grunt when needed

 

[rogerzilla]

Jags always had big straight sixes before the V12. There is an rpm limit as things get bigger, though - big pistons take a lot of stopping at TDC and BDC. You can have enormous marine diesel straight sixes because they do about 300rpm.

Some racing V12s were absolutely tiny, and they used V12s so they could rev at stupid rpm with their tiny reciprocating masses.

 

[raleighnut]

Jags always had big straight sixes before the V12. There is an rpm limit as things get bigger, though - big pistons take a lot of stopping at TDC and BDC. You can have enormous marine diesel straight sixes because they do about 300rpm.

Some racing V12s were absolutely tiny, and they used V12s so they could rev at stupid rpm with their tiny reciprocating masses.

Yep especially when it was the 1.5 litre maximum engine size. Honda took the principle to the extreme with their 250cc 6 cylinder revving to 20,000 rpm and giving Mike 'the bike' Hailwood 2 world championships.

 

[Profpointy]

Yep especially when it was the 1.5 litre maximum engine size. Honda took the principle to the extreme with their 250cc 6 cylinder revving to 20,000 rpm and giving Mike 'the bike' Hailwood 2 world championships.

We saw the 250 six running on The Island. When I say "saw" there was this impressive noise then a grey blur for about 2 milliseconds and everyone was very excited about it

 

[raleighnut]

We saw the 250 six running on The Island. When I say "saw" there was this impressive noise then a grey blur for about 2 milliseconds and everyone was very excited about it

Micheal Dunlop riding it ?

 

[Profpointy]

Micheal Dunlop riding it ?

Sadly not !

 

[mustang1]

Much like Audi V8s

I was a passenger in an Audi the other day, on a twisty road and a bend came up.

Me: watch out! Why aren't you turning?
Driver: I am! I've got it on full lock!
Me: oh crap! Hit the brakes!
Driver: are you crazy? The back wheels are gonna lift off!
Me: why did you buy this damn V8?
Driver: this isn't even a V8, they're even worse!

 

[Conrad_K]

I've had a few v8's in my time. Rover V8's are gutless in standard form. They eat camshafts, eat gaskets, larger capacity Rover V8's drop cylinder liners, cracked blocks are common and their oil pumps are on a level that would make chinesium seem like chobham tank armour, not to mention they love to leave an oil slick on the roads....

Rover bought an engine designed in the late 1950s, then did the absolute minimum to it for the next forty or so years.

Most of their problems were self-inflicted. The slipping liners and cracked blocks, for example. The engine was designed with ribbed iron liners that were inserted into steel dies, and the engine was die-cast around them. But Rover didn't want to buy a die casting rig, so they made new molds and sand-cast the blocks, then bored and installed the liners later. They used straight liners without a step, so only friction held them in place... until they got hot, or there was some detonation, or the stars got into the wrong conjunctions, in which case the owner would suddenly get a very large pain in the wallet.

Darton will sell you a set of "top hat" sleeves and install them in your Rover otherwise-undamaged Rover block for only US$2,850. Such a deal! Or you can press a new sleeve in, drill a hole through the side of the block and bottom of the sleeve, and run a Grade 3 bolt in to keep the sleeve from moving. Neither option helps with the cracking problem though.


The gaskets on the American-made engines were embossed steel shims, and problems were basically unknown, other than corrosion from people not using the proper antifreeze. Buick 300s had 4 bolts per cylinder, Buick 215s had 5 bolts, and Oldsmobile 215s had 6 bolts per cylinder. Brabham used Olds blocks for the Repco-Brabham V8s. I'm not sure where Rover dropped the ball on the gaskets, but they're a problem.


The oil pumps... the original Buick design blew road kill, and Buick kept it on all their V8s until the end in the 1980s, and on the V6s until they moved to a snout-mounted pump in the later V6s. The pump-in-timing-cover thing was okay for an engine with a design life of 30,000 miles, but people expected a lot more than that by the 1990s.


The oil slicks were mainly from the 1950s-tech "rope" rear main seal. Almost all of them leaked, no matter who made them. Cars self-undercoated back then, and all roads had an oil stripe down the middle. But Rover kept the rope seal until long after the rest of the world went to lip seals.


Rover eventually addressed most of those problems. Then, having fixed them, stopped making the engines, because shooting yourself in the foot was the Rover way.

 

[GilesM]

This is an interesting modern version of Land Rover using a V8:

https://www.carmagazine.co.uk/car-news/first-official-pictures/land-rover/defender-octa/