Let's clarify the term "GT4"

[Flashback]

Mercedes has announced a 550PS capable M4 GT4 race car...

BMW?

 

[Porter]

And my point is it appears the sanctioning body is changing the spec for 2023. Porsche has indicated the GT4RS is built to homologation spec and is publishing 500PS. Mercedes has announced a 550PS capable M4 GT4 race car (depending on regulations) and Lotus drops a GT4 with 400PS? Talk about digging a hole for yourself.

It just seems odd that everyone would need to massively detune to compete. Why exert the effort to reach the new numbers?

I think we are talking about different things.

The spec for a given class changes substantially every few years, mostly to prevent over-optimization to a particular ruleset by manufacturers with very deep pockets. So the spec is expected to change, and in the case of GT4 the rules are typically released fairly early because the class is largely privateer-focused. In contrast, for super-professionalized race series at the highest levels (F1, WEC, etc) the sanctioning bodies release new spec changes much later in order to restrict the amount of development time that's available. But that's not what GT4 is about, it's designed to offer manufacturers a significant marketing activity for their road cars by building visually similar racing-specific products that they can sell to private teams and then construe as "similar" to the production vehicles for marketing purposes. The private teams that buy these factory assembled racing cars can then do (comparatively) light development to make the vehicle package operable and campaignable, though it's still a significant development effort required if they want to be competitive.

A new variant of a factory packaged race vehicle (as described when they marketing-release it) is often built targeting the next upcoming ruleset, because it takes time to do privateer team development and actually turn the untuned vehicle into something that can be competitive and supported for a season campaign. The claimed horsepower figure is rarely the important part of the announced spec, because that often gets adjusted by the team as part of their setup and tuning work with the vehicle, and then will change again by restrictions imposed by the sanctioning body to ensure the outright pace is roughly consistent between competitors. Or they add ballast or other measures, depending on the policy approach of the particular series.

The chassis architecture, cooling, gearbox and diffs, braking, and aero are way more important to the function and competitiveness of a race car in this type of sanctioned competition than the numeric engine output. I'm not saying that the new "RS" designated version of the GT4 Clubsport isn't a jump in development and performance from the previous one, because I'm sure that it is, but it likely isn't the claimed 75hp engine output difference that is the key improvement for actual racing. That bit is most important for the marketing, and for the video games.

 

[mjw930]

BMW?

Yes, I transposed something I was reading. Corrected

 

[Lankan]

I think we are talking about different things.

The spec for a given class changes substantially every few years, mostly to prevent over-optimization to a particular ruleset by manufacturers with very deep pockets. So the spec is expected to change, and in the case of GT4 the rules are typically released fairly early because the class is largely privateer-focused. In contrast, for super-professionalized race series at the highest levels (F1, WEC, etc) the sanctioning bodies release new spec changes much later in order to restrict the amount of development time that's available. But that's not what GT4 is about, it's designed to offer manufacturers a significant marketing activity for their road cars by building visually similar racing-specific products that they can sell to private teams and then construe as "similar" to the production vehicles for marketing purposes. The private teams that buy these factory assembled racing cars can then do (comparatively) light development to make the vehicle package operable and campaignable, though it's still a significant development effort required if they want to be competitive.

A new variant of a factory packaged race vehicle (as described when they marketing-release it) is often built targeting the next upcoming ruleset, because it takes time to do privateer team development and actually turn the untuned vehicle into something that can be competitive and supported for a season campaign. The claimed horsepower figure is rarely the important part of the announced spec, because that often gets adjusted by the team as part of their setup and tuning work with the vehicle, and then will change again by restrictions imposed by the sanctioning body to ensure the outright pace is roughly consistent between competitors. Or they add ballast or other measures, depending on the policy approach of the particular series.

The chassis architecture, cooling, gearbox and diffs, braking, and aero are way more important to the function and competitiveness of a race car in this type of sanctioned competition than the numeric engine output. I'm not saying that the new "RS" designated version of the GT4 Clubsport isn't a jump in development and performance from the previous one, because I'm sure that it is, but it likely isn't the claimed 75hp engine output difference that is the key improvement for actual racing. That bit is most important for the marketing, and for the video games.

Are these rules similar to those adopted during the single-make (or one-make) race series' that were the norm in the 70's, 80's, 90's and early 2000's?

Porsche were, and are, at the thick end of such a series with the Carrera Cup and IROC, which is what I remember from my days that I was into Porsches (over a 15-year period)?

 

[Hapkin]

I was at Hethel. The development GT4 car I saw and heard testing with Gav at the wheel had a 1900 Harrop supercharger so definitely significantly more HP than 400. It had sequential shifting and full racing harness and roll bar. Didn't get a chance to see what tires it was on.

 

[gtihk]

This keeps coming up in a lot of threads. I feel like maybe there's a lack of common knowledge around this issue, so let's talk about it.


Porsche 718 Cayman GT4 = special edition sport model street car. Intended and type approved for public road use. The "GT4" designation is a homage reference to the name of the racing class, but is not reflective of any actual racing qualification or homologation.

Lotus Emira GT4 = factory-built race car for privateer customer racing. Not legal for registration as a road car in any jurisdiction worldwide. "GT4" designation reflects the vehicle's FIA/SRO homologation for the GT4 competition class in multiple racing series worldwide.


So to be clear... the Emira GT4 is NOT a racier special version of the Emira road car, because it's not a road car. They are as different (functionally and legally) as a Ford sedan and a Ford farming tractor.

The Cayman GT4 is, conversely, not a race car, it's just named to sound like one for marketing purposes and because many owners like to play with them on race tracks. That's not the same as actual professional racing, which is a very different thing involving sanctioning bodies, a rule book, scrutineering, extensive tightly integrated safety equipment, and very explicitly managed competition. A Cayman GT4 road car cannot be entered in GT4 class competition because it meets almost none of the rules that define the class. The name GT4 is used as an aspirational marketing exercise only.

The Emira GT4 and the Cayman GT4 are not competitors, because they aren't even the same kind of object. They aren't intended for any of the same purposes, and don't live in the same context in the world. Different horses for different courses.

Happy to unpack this further, if anyone is interested.

The Porsche Cayman GT4 has not been very successful in racing. I hope the Emira will be better at that!

 

[VL3X]

Didn't get a chance to see what tires it was on.

The Emira GT4 runs Pirelli Slicks. 245s up front and 305s rear.

Full specs here.

 

[action_turtle]

The Emira GT4 runs Pirelli Slicks. 245s up front and 305s rear.

Full specs here.

Love to drive that! lol.

For some reason, i thought they were using the i4, just a rumor it seems