Straight six

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Marquis_Rex

Original Poster:

7,377 posts

244 months

Thursday 22nd July 2004
quotequote all
I just found out that the straight six engine in the Rover SD1 (2.3 litre and 2.6 litre) only had 4 main bearings in the crank!

I can't believe it! Why did they do it? For friction? It's already well known for seizing up it's valvetrain due to sludging up of the small oil way to the cylinder head. Even the cast iron Triumph engines that there were designed to replace had 7 main bearings. How many counterweights did these things have then? What a heap of turd!
In keeping with the under- engineered mentality- I wonder if they bothered to tune the Torsional vibrations out with the TV damper properly?

The contemporary BMW M20 straight six of the late 70's made more power per litre (323i 143 Bhp vs 2.3 litre Rover- 115 (?) Bhp), was more economoical, made more torque, the unit was lighter, physcially much smaller and more robust and tougher. And Brit-o-philes wonder why customers turned away from British leyland in the 70s/80s......

joospeed

4,473 posts

283 months

Thursday 22nd July 2004
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do the cranks break on this engine? or this there any other crank flex / crankcase flex issues that it suffers from? if not I'd say they engineered it just right ..

Marquis_Rex

Original Poster:

7,377 posts

244 months

Thursday 22nd July 2004
quotequote all
There are TV issues I've heard of. However,the cylinder head usually seize first

In all seriousness, an engine-especially a car engine shouldn't just be judged on its ability to last- its NVH characteristics and other metrics such as fuel economy- should be looked into too. A 4 bearing crank would effect NVH adversely.
And the cost argument falls down, when you compare how many straight six engines SD1s were sold compared to M20 engines Bimmers. Good engineering sells more in the LONG term then fancy marketing....

Incorrigible

13,668 posts

266 months

Thursday 22nd July 2004
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Most of the engines that came out of BL in the 70s were shit look at B series vs rootes group cars, the buik compared to the stag and daimler V8 of the same era

Bare bones of stuff was there but too much bitching and not develolpng the right stuff

Jools is right though, if you know you're making a shit engine it doesn't need to be strong, but you can hardly go anywhere from that

Marquis_Rex

Original Poster:

7,377 posts

244 months

Thursday 22nd July 2004
quotequote all
Despite being Cast iron and push rod I even think the Triumph predessor engine - as used in the 2500 saloons and TR6s etc etc is better. The Rover was meant to replace it, as the SD1 was deemed as a replacement to Triumph 2500 saloons.

The Edward Turner 2.5 litre Daimler V8 is a DREAM engine. I have some original hand drawn power curves for that engine, taken off the dynos! I believe the engine was developed with similar architechture to a comtemporary motor cycle engine. It is meant to be puchrod actuated, but the push rods are more like rockers, and the engine likes to rev! I don't know how much it has in common with the Daimler 4.4 litre engine- its a shame it wasn't developed further.....the 4.4 litre would have been nice in either a Daimler SP250/Dart or the Mk2Jag/Daimler.

danhay

7,460 posts

261 months

Thursday 22nd July 2004
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I had a Rover 2600S a couple of years ago, and it didn't seem to suffer from too much NVH...nowhere near a silky as the 2 litre BMW 6 I had of the same vintage though.

Wacky Racer

38,747 posts

252 months

Thursday 22nd July 2004
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Marquis_Rex said:
The Edward Turner 2.5 litre Daimler V8 is a DREAM engine.



My mate had a high mileage V8 Daimler around 1970, and we were out cruising around in it one night, and there was an almighty bang......

We lifted the bonnet to find one of the con rods was sticking out of the crankcase.....

The look on my friend's face was a picture.......

Marquis_Rex

Original Poster:

7,377 posts

244 months

Thursday 22nd July 2004
quotequote all
Wacky Racer said:

Marquis_Rex said:
The Edward Turner 2.5 litre Daimler V8 is a DREAM engine.




My mate had a high mileage V8 Daimler around 1970, and we were out cruising around in it one night, and there was an almighty bang......

We lifted the bonnet to find one of the con rods was sticking out of the crankcase.....

The look on my friend's face was a picture.......


Oh man! That's aweful- was he gunning it at the time?

GavinPearson

5,715 posts

256 months

Friday 23rd July 2004
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Marquis_Rex said:
Despite being Cast iron and push rod I even think the Triumph predessor engine - as used in the 2500 saloons and TR6s etc etc is better. The Rover was meant to replace it, as the SD1 was deemed as a replacement to Triumph 2500 saloons.

The Edward Turner 2.5 litre Daimler V8 is a DREAM engine. I have some original hand drawn power curves for that engine, taken off the dynos! I believe the engine was developed with similar architechture to a comtemporary motor cycle engine. It is meant to be puchrod actuated, but the push rods are more like rockers, and the engine likes to rev! I don't know how much it has in common with the Daimler 4.4 litre engine- its a shame it wasn't developed further.....the 4.4 litre would have been nice in either a Daimler SP250/Dart or the Mk2Jag/Daimler.


The PE I worked for in Transmissions was a designer for that Engine. There was Turner and two guys who did the entire unit in the Radford DO. Trevor Commins was his name. Nice guy, very good to work for, very experienced.