Simple question on the Lm's ~

[jcsaleen]

Are the Lm's the original GTR's converted for road use or are they separate chassis from the orignal GTR's?

Thanks
Jc

[Sauc3]

Originally Posted by jcsaleen

Are the Lm's the original GTR's converted for road use or are they separate chassis from the orignal GTR's?

Thanks
Jc

All original LMs - LM1 thru 5 and XPLM - are seperate chassis from the GTRs. They were built to commemorate the '95 Le Mans results, 5 cars - 1 for every place that the GTRs finished at LM.

There have been GTRs converted to Le Mans lookalikes - 11R and 16R and some more that I can't remember right now. The main difference between these cars and the LMs are the engine - the LM had a special version with 691hp and orange covers, making for a very distinct look - and the right seat, which in GTRs remains a bank of controls, in the LM it's a carbon bucket with thin strips of seat material.

I'm sure there's stuff I forgot, but that's the basis of it.

[Peloton25]

LMs were totally separate chassis from the GTRs my friend.

Many GTRs have been converted or refitted to look a lot like the LMs. In fact the Australian who owned #16R prior to mr briger taking posession had the factory fit the interior to look similar as well. There are all most more look-a-like GTRs than there are real LMs now, and there are certainly more of them painted orange than there were orange LMs originally.

>8^)
ER


This is what happens when you don't hit submit on the reply you typed an hour ago...

[Peloton25]

The Papaya painted GTRs are #07R, #08R, #11R, #14R or #15R, and #16R.

>8^)
ER

[hurstg01]

If it were me I'd try to keep the racing colours instead of changing a GTR to be a LM-lookalike.

[jcsaleen]

? #2

What exactly is done to up the power on the F1's engine to make it produce the hp levels of the LM?

[hurstg01]

The LM engine is derived from the GTR engines. The GTR had inlet air restrictors in place for the racing series they participated in and were removed for the LM. The LM is effectively an endurance racing GTR. The GTR produced around 636bhp, the LM around 668bhp.

[Sauc3]

Originally Posted by hurstg01

The LM engine is derived from the GTR engines. The GTR had inlet air restrictors in place for the racing series they participated in and were removed for the LM. The LM is effectively an endurance racing GTR. The GTR produced around 636bhp, the LM around 668bhp.

Where did I pull 691bhp from? Or was that the roadcars with LM engines with somehow more HP?

[hurstg01]

Originally Posted by Sauc3

Where did I pull 691bhp from? Or was that the roadcars with LM engines with somehow more HP?

Dunno?, mine came from DA

[Peloton25]

691hp was the power figure quoted in the Christie's auction info for chassis #073.

LMs are often quoted at either 668hp or 680hp which I believe might be attributed to basic calculation variances when converting from Kw to Hp. I prefer to stick with McLaren's quoted figure of 680hp found on the LM spec sheet in "Driving Ambition" and in the CAR Magazine 0-100-0 test. Funny enough though, the text in the chapter of DA on the LM includes a photo caption that says the LM engines "were tuned to develop 41bhp more than the standard production units" which when added to stock F1s 627hp would equal the 668hp figure on the nose. RacingLine magazine also used the 668hp figure in speaking about the LM in one article (8/1998) and the 680hp figure in another (11/1999) so who knows...

As for how the LM actually makes its extra power, I believe the intake and exhaust cam profiles were changed and the air/fuel curves were altered to make better use of that revised airflow. The car was also fitted with a more freely flowing exhaust system, sans catalytic convertors. Anytime you make an engine breathe more efficiently and accompany that with appropriate changes in the fuel mapping, you should theoretically see a power increase. The increase seen on the LMs is less than 10% in total and not surprising to me - in fact I suspect if drivability were not a concern they could have pushed the limits a little further.

I don't believe there were any other internal changes to the engine as the LM shares the road car's 11:1 compression ratio. Later GTRs did see an increase to 12:1, likely from a connecting rod or piston change, or possibly a reduction in height of the engine block, however, I am not certain which method was used. LeMan may be able to expand on that with his superior GTR knowledge.

>8^)
ER

[Le Man]

Originally Posted by Peloton25

691hp was the power figure quoted in the Christie's auction info for chassis #073.

LMs are often quoted at either 668hp or 680hp which I believe might be attributed to basic calculation variances when converting from Kw to Hp. I prefer to stick with McLaren's quoted figure of 680hp found on the LM spec sheet in "Driving Ambition" and in the CAR Magazine 0-100-0 test. Funny enough though, the text in the chapter of DA on the LM includes a photo caption that says the LM engines "were tuned to develop 41bhp more than the standard production units" which when added to stock F1s 627hp would equal the 668hp figure on the nose. RacingLine magazine also used the 668hp figure in speaking about the LM in one article (8/1998) and the 680hp figure in another (11/1999) so who knows...

As for how the LM actually makes its extra power, I believe the intake and exhaust cam profiles were changed and the air/fuel curves were altered to make better use of that revised airflow. The car was also fitted with a more freely flowing exhaust system, sans catalytic convertors. Anytime you make an engine breathe more efficiently and accompany that with appropriate changes in the fuel mapping, you should theoretically see a power increase. The increase seen on the LMs is less than 10% in total and not surprising to me - in fact I suspect if drivability were not a concern they could have pushed the limits a little further.

I don't believe there were any other internal changes to the engine as the LM shares the road car's 11:1 compression ratio. Later GTRs did see an increase to 12:1, likely from a connecting rod or piston change, or possibly a reduction in height of the engine block, however, I am not certain which method was used. LeMan may be able to expand on that with his superior GTR knowledge.

>8^)
ER

Thankyou Erik, for your compliment in your last paragraph

As I have not got my GTR bible,s to hand at the moment, I shall give a brief answer for now.

As to the LM spec engine producing more peak bhp, To add to the list in Erik,s reply. This is also due to the deletion of the GTR,s air restrictors that they had to operate with by the regulations of the race series. It is a known fact that the S/70-2 engine is capable of close to 1,000 bhp, but this would only be for circuit use and definately not viable for endurance racing.

However the most important measure of power, produced by any engine, is not how much bhp it produces. But how much torque is generated and over as wide a rev range, right up to its red line. This we rarely see in graph form, just wish the dyno sheet was public knowledge when XP1LM was run on an independent dyno.

[hurstg01]

^^

True, if only.........

[cabrio92]

Hello,

an interesting discussion again.

I add there is sometimes a confusion with hp and bhp ! I remember read 691bhp for #11, which means 700hp ! Is it possible ?

I think it's quite hard to find true power figures. I have a question : I often read 610hp for the road car instead of 627, why ?
And another the incredible weight of 1138kg was verified ? And with fuel, etcd ?

Thanks

Phil

[Peloton25]

Originally Posted by Le Man

Thankyou Erik, for your compliment in your last paragraph

But, of course...

This is also due to the deletion of the GTR,s air restrictors that they had to operate with by the regulations of the race series.

I left that portion out partially because Greg had already made mention, and also because I was basing my comments on the difference between stock F1 and LM-spec, not GTR to LM-spec.

Now, we know the LMs were allowed to breathe more freely than the GTRs, but do you have any idea if the intake track was in any way larger on the LMs than a standard road car? I don't recall seeing any commentary on that from any sources.

This uncertainty is kind of common with special road cars that are created from race cars that were originally spawned from road cars. I'm thinking of the Ferrari 360/F430 -> 360C/F430C -> 360CS/F430S as a more common example. It is often hard to know which pieces came from the original road car, which ported over from the racer, or are simply unique to the special road version.

>8^)
ER

[Le Man]

Originally Posted by Peloton25

Now, we know the LMs were allowed to breathe more freely than the GTRs, but do you have any idea if the intake track was in any way larger on the LMs than a standard road car? I don't recall seeing any commentary on that from any sources.



>8^)
ER

LM specification :- unrestricted 85mm inlets

95 GTR :- restricted 39mm inlets

Info from Autocar mag 13th december 95, eight page article on XP1LM.

I shall check later for the road car spec.