Off topic: car engine question

[Ext User(Patrick)]

Looking at a magazine article about the old Lotus Carlton Omega, it gave
specs as a 3.6 litre, at 0.7 bar boost, giving 562 Nm. This is 92
Nm/litre if you allow for the boost to increase effective engine volume
at 100% efficiency.

Now a more modern engine, also famous for bulk turbo torque, would be
the twin turbo supra. This is a 3.0 litre at 0.8 bar giving 420 Nm. This
gives 78 Nm/litre.

Likewise with power, the old Lotus got 46 kW/litre at 5600 rpm and the
Toyota 41 kW/litre at 5800 rpm, even if we assume the Toyota was running
220 kW rather than the claimed 207.

So given they are both twin cam, 4 valve sixes with twin turbos and
running similar boost. And given the Lotus was a low budget effort
compared to the later toyota engine, how come the Lotus does so much better?

[Ext User(jackbadger56)]

On Nov 30, 11:58 am, Patrick <doctor...@spiced-luncheon-meat-
bigfoot.com> wrote:
> Looking at a magazine article about the old Lotus Carlton Omega, it gave
> specs as a 3.6 litre, at 0.7 bar boost, giving 562 Nm. This is 92
> Nm/litre if you allow for the boost to increase effective engine volume
> at 100% efficiency.
>
> Now a more modern engine, also famous for bulk turbo torque, would be
> the twin turbo supra. This is a 3.0 litre at 0.8 bar giving 420 Nm. This
> gives 78 Nm/litre.
>
> Likewise with power, the old Lotus got 46 kW/litre at 5600 rpm and the
> Toyota 41 kW/litre at 5800 rpm, even if we assume the Toyota was running
> 220 kW rather than the claimed 207.
>
> So given they are both twin cam, 4 valve sixes with twin turbos and
> running similar boost. And given the Lotus was a low budget effort
> compared to the later toyota engine, how come the Lotus does so much better?

OK, can't really definitively answer the above, but I do remember
reading an interview with the chief engineer of that Lotus Carlton
engine, and he made a big thing about treating the engine as 2 x 3 cyl
engines joined at the hip; this was in regards to inlet manifolding
and air intake, exhaust, and turbo plumbing, and other items that I
can't remember. I really didn't understand it further when he started
getting overly technical, but the 2 x 3 cyl thing he seemed to make a
big deal about.
BTW the interview was in CAR Magazine in the early 90's, so I'm very
doubtful of finding it on line ;-(

[Ext User(John_H)]

Patrick wrote:

>Looking at a magazine article about the old Lotus Carlton Omega, it gave
>specs as a 3.6 litre, at 0.7 bar boost, giving 562 Nm. This is 92
>Nm/litre if you allow for the boost to increase effective engine volume
>at 100% efficiency.
>
>Now a more modern engine, also famous for bulk turbo torque, would be
>the twin turbo supra. This is a 3.0 litre at 0.8 bar giving 420 Nm. This
>gives 78 Nm/litre.
>
>Likewise with power, the old Lotus got 46 kW/litre at 5600 rpm and the
>Toyota 41 kW/litre at 5800 rpm, even if we assume the Toyota was running
>220 kW rather than the claimed 207.
>
>So given they are both twin cam, 4 valve sixes with twin turbos and
>running similar boost. And given the Lotus was a low budget effort
>compared to the later toyota engine, how come the Lotus does so much better?

Forgetting power (which is determined by factors other than
displacement alone), you'd expect torque to be directly proportional
to the effective displacement (which is the way you've calculated the
specific torque figures). A figure of 85 to 90 Nm/litre is probably
around typical for that engine configuration... either naturally
aspirated or as a product of boost. The exact figure being dependant
on the natural VE (which will be something less than 100%).

So what's the actual boost (by measurement) at the maximum torque rpm
for both these engines?

My guess is that the Supra would be running something less than than
the stated 0.8 bar (assuming the torque figure is correct).

--
John H

[Ext User(Patrick)]

John_H wrote:
> Patrick wrote:
>
>> Looking at a magazine article about the old Lotus Carlton Omega, it gave
>> specs as a 3.6 litre, at 0.7 bar boost, giving 562 Nm. This is 92
>> Nm/litre if you allow for the boost to increase effective engine volume
>> at 100% efficiency.
>>
>> Now a more modern engine, also famous for bulk turbo torque, would be
>> the twin turbo supra. This is a 3.0 litre at 0.8 bar giving 420 Nm. This
>> gives 78 Nm/litre.
>>
>> Likewise with power, the old Lotus got 46 kW/litre at 5600 rpm and the
>> Toyota 41 kW/litre at 5800 rpm, even if we assume the Toyota was running
>> 220 kW rather than the claimed 207.
>>
>> So given they are both twin cam, 4 valve sixes with twin turbos and
>> running similar boost. And given the Lotus was a low budget effort
>> compared to the later toyota engine, how come the Lotus does so much better?
>
> Forgetting power (which is determined by factors other than
> displacement alone)

Yeah, but once you've specified rpm, it is only determined by torque.
Still I suppose there is no reason to suppose that peak boost is held
all the way to peak power, and the Lotus probably doesn't drop off as much.

, you'd expect torque to be directly proportional
> to the effective displacement (which is the way you've calculated the
> specific torque figures). A figure of 85 to 90 Nm/litre is probably
> around typical for that engine configuration... either naturally
> aspirated or as a product of boost. The exact figure being dependant
> on the natural VE (which will be something less than 100%).
>
> So what's the actual boost (by measurement) at the maximum torque rpm
> for both these engines?
>
> My guess is that the Supra would be running something less than than
> the stated 0.8 bar (assuming the torque figure is correct).

I'd have assumed that max boost is at max torque, but I suppose I could
be very wrong.

Then again, the boost figures come from opposite sides of the world,
years apart. The measurement technique or location could be completely
different. (eg. Lotus might measure in the manifold, toyota might
measure directly after the turbo, before the intercooler and piping.
Both are reasonable positions, and could well explain the difference.)


>

[Ext User(Toby Ponsenby)]

On Fri, 30 Nov 2007 11:58:52 +1100, Patrick blathered on in :

> Looking at a magazine article about the old Lotus Carlton Omega, it gave
> specs as a 3.6 litre, at 0.7 bar boost, giving 562 Nm. This is 92
> Nm/litre if you allow for the boost to increase effective engine volume
> at 100% efficiency.
>
> Now a more modern engine, also famous for bulk turbo torque, would be
> the twin turbo supra. This is a 3.0 litre at 0.8 bar giving 420 Nm. This
> gives 78 Nm/litre.
>
> Likewise with power, the old Lotus got 46 kW/litre at 5600 rpm and the
> Toyota 41 kW/litre at 5800 rpm, even if we assume the Toyota was running
> 220 kW rather than the claimed 207.
>
> So given they are both twin cam, 4 valve sixes with twin turbos and
> running similar boost. And given the Lotus was a low budget effort
> compared to the later toyota engine, how come the Lotus does so much
> better?

IMHO it's that way because Lotus was prepared to turn out a warmer device
from the factory door than Toyota, whose factory engines with very few
exceptions have always been kinda mild.

Of course there are 'emissions' matters, too.




--
Toby

[Ext User(monsya)]

On Nov 30, 11:58 am, Patrick <doctor...@spiced-luncheon-meat-
bigfoot.com> wrote:
> Looking at a magazine article about the old Lotus Carlton Omega, it gave
> specs as a 3.6 litre, at 0.7 bar boost, giving 562 Nm. This is 92
> Nm/litre if you allow for the boost to increase effective engine volume
> at 100% efficiency.
>
> Now a more modern engine, also famous for bulk turbo torque, would be
> the twin turbo supra. This is a 3.0 litre at 0.8 bar giving 420 Nm. This
> gives 78 Nm/litre.
>
> Likewise with power, the old Lotus got 46 kW/litre at 5600 rpm and the
> Toyota 41 kW/litre at 5800 rpm, even if we assume the Toyota was running
> 220 kW rather than the claimed 207.
>
> So given they are both twin cam, 4 valve sixes with twin turbos and
> running similar boost. And given the Lotus was a low budget effort
> compared to the later toyota engine, how come the Lotus does so much better?

Haha! Glad you marked this one as off-topic! You are talking about
engines... weirdo! Is there no depth that somepeople won't sink to :)

It's a realy worry that I didn't see the irony earlier, but I guess I
have been conditioned...

Dale.

[Ext User(Legoman)]

On Fri, 30 Nov 2007 11:58:52 +1100, Patrick
<doctorpat@spiced-luncheon-meat-bigfoot.com> wrote:

>Looking at a magazine article about the old Lotus Carlton Omega

Only the Lotus badged one was called the Carlton. The Omega was the Opel
branded one. Lotus for UK, Opel for the rest of Europe.