Cayman S 987.1 3.4 Tuning

[jamsp00n]

jayxx83 said:

I picked up 35 hp and 60 lb ft from an M&M system on a 2.9 boxster.

Original 255 ps and then 290 ps after live remap
Tq was 215 stock and 275 after

While this stuff ultimately isn't about numbers, do these figures not give you (and whoever produced them for you) pause for thought?

For an NA lump, that's not just a good specific torque figure post mods, it's absolutely, positively spectacular. On a 2.9, it works out to just under 95ft/lb per litre. Current 992 GT3 4.0 is 87ft/lb per litre, Cosworth V12 in the Murray T.50 is 88ft/lb per litre, as is a Ferrari 458, oh and the bigger 6.2 Cosworth lump in the Valyrie, that's 88 too. An 812 Superfast is 82. A slightly more old school / lazier lump like the 6.2 V8 in a Merc AMG SLS is 77ft/lb per litre.

The Mclaren Solus thing which is track only and doesn't have to meet emissions regs with its Judd V10 lump is 92ft/lb per litre. Just about the only thing I can think of that would match or maybe beat 95ft/lb per litre is an F1 motor from the late NA era. The last 2.4 V8 engines were (I think) about 98ft/lb per litre.

Anything over 80 would be a very good outcome. 85 and up (roughly) I'd have thought a bit suspect on that engine short of a full scale re-engineering effort. But 95?

[jayxx83]

Tbh re the above. Never really thought that deeply about it. The car drives nicely.

If you look at GADs other results on their Instagram page the stock runs on most cars are pretty spot on. They have nothing to gain by overrating bhp as they are busy enough as it is. Talk to them and they are all about reliability and not peak numbers guys. Lovely chaps.

I guess the engines you are comparing to are more the high revving highly strung variety that dont need as much torque. The power at 285 hp isnt great from almost 3 litres vs a Honda f20c for example producing 240hp from a 2.0 but only 162 lb ft.

All engines are different. Tbh I couldn't care less if it was 220lb ft (stock is supoosed to be 214). The way the car is balanced power and handling wise is just right now. Not too much but enough so you can enjoy riding the torque on a short shift etc.

I too was sceptical when I saw the print out, but having had a 3.4 spyder which from factory made 273 lb ft, once i drove it, she feels pretty much the same as that, just not a crazy rush of power past 6.5k like the 3.4 did.

[jamsp00n]

jayxx83 said:

I guess the engines you are comparing to are more the high revving highly strung variety that dont need as much torque. The power at 285 hp isnt great from almost 3 litres vs a Honda f20c for example producing 240hp from a 2.0 but only 162 lb ft.

Yeah, that's really not how it works re the engines "not needing torque" if highly strung or whatever.

I prob wasn't clear enough. Those engines I quoted with 88ft/lb per litre have the highest specific torque of any NA road car engine from a significant OEM. Well, that I am aware of. There may be one or two with very slightly higher figures than 88ft/lb per litre, but it won't be much if so.

"Highly strung" / "high revving" does not mean low torque. On the contrary, though where that torque is made in the rev range is obvs another matter. There's very much a plausible limit to how much torque per litre an NA engine will make. Again, that's why even the most exotic F1 engine only beats road car engines by a relatively small margin in that measure.

If you take superficially less highly tuned engines, like say the 5.0 V8 in the Lexus LC500 (80ft/lb per litre), you'll find they make a bit less torque / litre than the really highly strung Ferrari and Porsche GT lumps, not more. Go for something lazier and the torque / litre figure will only be lower still.

Anyway, either an exhaust and map has turned your 2.9 lump into an engine with a spectacular specific torque output the likes of which the great engine development minds at Ferrari, Porsche and Cosworth can't get close to. Or whoever did the numbers got them off by quite a long way. Personally, if I was paying money and I was being given numbers like that, it would give me pretty major pause for thought!

People tend to take less notice of torque figures, but the plausibility test is ultimately the same. If you were beating the world's best for specific power output by a similar proportion you'd be making at least 150hp/litre and well over 400hp from a map and exhaust. The point is that 95ft/lb per litre is every bit as implausible as 150hp / litre if not more so.

[Slippydiff]

jamsp00n said:

jayxx83 said:

I guess the engines you are comparing to are more the high revving highly strung variety that dont need as much torque. The power at 285 hp isnt great from almost 3 litres vs a Honda f20c for example producing 240hp from a 2.0 but only 162 lb ft.

Yeah, that's really not how it works re the engines "not needing torque" if highly strung or whatever.

I prob wasn't clear enough. Those engines I quoted with 88ft/lb per litre have the highest specific torque of any NA road car engine from a significant OEM. Well, that I am aware of. There may be one or two with very slightly higher figures than 88ft/lb per litre, but it won't be much if so.

"Highly strung" / "high revving" does not mean low torque. On the contrary, though where that torque is made in the rev range is obvs another matter. There's very much a plausible limit to how much torque per litre an NA engine will make. Again, that's why even the most exotic F1 engine only beats road car engines by a relatively small margin in that measure.

If you take superficially less highly tuned engines, like say the 5.0 V8 in the Lexus LC500 (80ft/lb per litre), you'll find they make a bit less torque / litre than the really highly strung Ferrari and Porsche GT lumps, not more. Go for something lazier and the torque / litre figure will only be lower still.

Anyway, either an exhaust and map has turned your 2.9 lump into an engine with a spectacular specific torque output the likes of which the great engine development minds at Ferrari, Porsche and Cosworth can't get close to. Or whoever did the numbers got them off by quite a long way. Personally, if I was paying money and I was being given numbers like that, it would give me pretty major pause for thought!

People tend to take less notice of torque figures, but the plausibility test is ultimately the same. If you were beating the world's best for specific power output by a similar proportion you'd be making at least 150hp/litre and well over 400hp from a map and exhaust. The point is that 95ft/lb per litre is every bit as implausible as 150hp / litre if not more so.

Interestingly, M&M/FVD quote a power increase (+25hp) for the system, which is broadly in line with what jayxx83 states his car is producing, especially bearing in mind the live remap his car was subject to, so 30hp doesn't seem unreasonable. What doesn't make sense is the torque figure, which M&M/FVD state should be 26 additional torques

As I said previously, fitment of the full M&M system to a Mk1 996 GT3 with 360hp, sees them produce 390-395hp, again with a live remap.

The full Manthey K400 conversion which utilises the same exhaust system, but swaps the ignition and fuelling management to Alpha N and ditches the stock airbox and replaces it with a Cup air filter and cold air ducting, sees the engine producing 400-405hp and liberates an additional 30 torques.

This is FVD's version without the cold air ducting the Manthey K400 utilises :

https://www.fvd.net/de-en/FVD99610033A/996-gt3-lev...

All of which makes the figure of 60 torques increase with the 2.9 engine somewhat questionable.