Cayman S 987.1 3.4 Tuning - Page 2 - Boxster/Cayman - PistonHeads UK

Hi folks, The last thread I can find on this is from 2013, so thought I'd risk a new post. I'm going to be moving on from my 996.1 C2 3.4 Manual Coupe this weekend, and getting a 987.1 3.4 Cayman (yep, I like my Porsche to have an inherent design flaw with the engine). I've been reading that it is suprisingly achievable to make good power gains with this engine. The car has a Dansk exhaust fitted, but it sounds like if I do: Manifold & 200 Cell cats IPD Plenum & GT3 Throttle Body Tune I would be close to ~350 bhp. Not to be sniffed at. Has anyone done these mods or similar?

conanius said: Hi folks, The last thread I can find on this is from 2013, so thought I'd risk a new post. I'm going to be moving on from my 996.1 C2 3.4 Manual Coupe this weekend, and getting a 987.1 3.4 Cayman (yep, I like my Porsche to have an inherent design flaw with the engine). I've been reading that it is suprisingly achievable to make good power gains with this engine. The car has a Dansk exhaust fitted, but it sounds like if I do: Manifold & 200 Cell cats IPD Plenum & GT3 Throttle Body Tune I would be close to ~350 bhp. Not to be sniffed at. Has anyone done these mods or similar? A near 55hp increase from manifolds, cats throttle body and tune ? Sorry to rain on your parade, but I'm extremely dubious. And when someone like Wayne Schofield of Chipwizards says larger throttle bodies and IPD plenums generally are a waste of money, they tend to be worth listening to : Bigger Throttle Body Nonsense I love my dyno, it’s great. It doesn’t suffer from any placebo effects, it doesn’t read biased rubbish on the internet, it doesn’t try to sell you anything or try to convince itself that its most recent purchase was not a total waste of money and it doesn’t flatter with "suits you, Sir” lies; it just measures what is being produced and shows it, warts an’ all. So, now that’s out of the way, let’s look a little bit at HOW engines breathe, since that’s what induction changes seemingly set out set out to improve….. Suck, squeeze, bang, blow right? Yes of course, mostly. However, imagine that a given engine has a cylinder capacity of say, 3000cc, so each revolution it would DISPLACE 1500cc (1.5 litres), and that it’s running at 6000 rpm; that’s 100 revs per second so 50 CYCLES per second and thus, 150 litres per second @ 100% Volumetric Efficiency (VE). Think about that, a hundred and fifty litres per SECOND. Well, given how fast that is all happening the VE isn’t going to be anything like 100%, is it, because there’s so little time to fill and empty the cylinders, right? All the little restrictions along the way; air filter, trunking, intake silencer, throttle body, plenum chamber, intake runners, ports in the cylinder head, past the valves (which are closed for more than half of the time) and that’s just to get TO the cylinder, after all that it’s still got to get out…. SO…. what would you realistically expect the VE to be in such circumstances? Well, if you were to put a huge vacuum cleaner sucking at an unrestricted rate of 150 l/s (saving the piston’s uppy-downy motions from doing the job) pulling air through to the cylinders you’d get, perhaps 75% of the potential unrestricted flow. In that case there’s 25% of the potential flow lost to the restrictions. You’re never going to get ZERO restriction because there’s far too much other necessary stuff in the engine and engine bay to fit filter, trunking, manifold and ports of sufficient proportions to have zero restriction. A modern engine is pretty good out of the box and you wouldn’t ever expect as much as a 5% improvement in flow without drastic changes, and those very same drastic changes would likely make things worse in other ways. So, best ways up you might see 78 or 79% of the potential flow. How come then, a typical modern high-performance road car engine has a VE of as much as 120%? Yes, a 3 litre engine would breathe as much as 3600cc in two revolutions! With its silly uppy-downy pistons, pulling air past valves that are only open for typically 36% of the time, through ports that often have rough surfaces and uneven profiles, through often convoluted trunking and in from the outside world through a filter that only has open areas of a few microns. It cannot possibly be, surely? That’s over 50% more than the possible flow when the valves are only open for 36% of the time and the piston is only on the induction stroke for half of a revolution. "Get the ducking stool ready people, something isn’t right…..” Well it can and it does, using PRESSURE WAVES. Tuning pressure waves is what it’s all about. Camshafts, exhausts, intake systems SHOULD all work absolutely together to harness the highs and lows of the pressure waves to best effect; so effective in fact that it amounts to a very significant supercharging effect. Flow plays a very low second fiddle to pressure waves when it comes to tuning, because the difference that a loss of wave amplitude makes is far greater than the potential flow ‘increase’ from having a larger diameter and guess what? When the diameter of a pipe increases, the amplitude of the waves within it reduce because the molecule compression occurs over a greater area (the surface area, if you will, of the pipe section), so while the static flow may be imagined to be greater, the dynamic flow is actually considerably less. For example, just look at a GT or F3 airbox - the airbox is huge to harness the pressure waves but the inlet FLOW is through a tiny little inlet restrictor, and despite this the engines still make PLENTY of power. A flat six engine (all sixes actually for a specific reason that we don’t need to entertain here) is particularly well suited to harnessing the pressure waves that travel back and forth into, as well as across, the manifold if allowed to. They can make a huge difference to the VE at some engine speeds. This is why the (not stupid) design engineers at Porsche have gone to such great lengths to make best use of the pressure waves by employing various flaps in the system to either block or allow passage of pressure waves within the system. When developing their engines manufacturers will do many, many hours of simulation work. After that they will make many test pieces, probably at least twenty different head casting designs, fifty camshaft profiles, piston crown designs, valve head shapes, compression ratios, manifold designs, you name it. At each engine test, a zillion sensors and probes are mounted all over the engine measuring everything that can be measured. DO YOU NOT THINK THAT AT SOME POINT IN ALL THAT IT WOULD HAVE BECOME APPARENT TO THEM THAT IT NEEDED A BIGGER THROTTLE BODY? No, of course not, they’re all stupid those Germans, right ? It takes Fred in his shed with probably zero engine design expertise, to think "Gad Daim, I can fit me a bigger throddle on there an’ life will be reeeeeal gewd….” If only things were that simple….. In the vast majority of cases BIGGER THROTTLE INTAKES DON’T WORK so save your money. In every single Porsche case that I have EVER had on the dyno, NO bigger intake has made an improvement, and almost ALL has made less area under the curve than stock. When a vendor selling parts says "There’s a 25 bhp difference with this Big-Boy Carlos Fandango intake Sonny Jim” just consider whether he means UP or DOWN!!!!!! (Chipwizards - Wayne Schofield)

I too was dubious, but the internet is littered with pre and post dynos that suggest its possible as the early 987.1 was quite restricted. https://www.pistonheads.com/gassing/topic.asp?h=0&... https://www.pistonheads.com/gassing/topic.asp?h=0&... https://www.pistonheads.com/gassing/topic.asp?h=0&...

conanius said: I too was dubious, but the internet is littered with pre and post dynos that suggest its possible as the early 987.1 was quite restricted. https://www.pistonheads.com/gassing/topic.asp?h=0&... https://www.pistonheads.com/gassing/topic.asp?h=0&... https://www.pistonheads.com/gassing/topic.asp?h=0&... Ah yes, Mr Demon aka GT4, 911R, or whatever his username is this week. If you want to know what power/torque figures are attainable with bolt ons and a live re-map, ring, email or better still, use Wayne Schofields's messaging service and ask him directly. If those are the numbers you're hoping for, just ask him, he'll tell you if it's possible, and he'll do so with no BS, he'll also tell you exactly what components you'll need (and more importantly, don't need) to get the figures, if they are attainable.

I don't see why anyone would be dubious about this. The same engine in the 911 already makes 350bhp, so the engine is deliberately detuned for the Boxster/Cayman to ensure that they don't outperform the 911. I believe a smaller intake plenum, smaller throttle body and ECU tune are used to achieve this. All you have to do is restore these to standard 911 spec and you should have Carrera power levels and better is possible.

LunarOne said: I don't see why anyone would be dubious about this. The same engine in the 911 already makes 350bhp, so the engine is deliberately detuned for the Boxster/Cayman to ensure that they don't outperform the 911. I believe a smaller intake plenum, smaller throttle body and ECU tune are used to achieve this. All you have to do is restore these to standard 911 spec and you should have Carrera power levels and better is possible. Sorry, maybe a poor choice of words on my part Your logic is exactly why I didn't think this was fantasy. Lets see what happens and I'll report back.

You’re not getting close to 350bhp for a 3.4l with bolt ons and a tune. I had a Hartech 3.7 with a manifold, 200 cell cats, exhaust and a tune from Chipwizards in my old 996 and it produced 330 bhp and 300lbft (which was more than other similarly specified cars. Altogether you wouldn’t get much, if any change out of £15k for that. Edited by Greedydog on Wednesday 6th March 11:57

Yeah, I think +50bhp is a pipe dream without substantial reworking. I.e. Cams and a rev limit the engine won't like. If you want that power grab a 3.8 and swap it.

conanius said: Manifold & 200 Cell cats IPD Plenum & GT3 Throttle Body Tune Quality versions of the above (well, quality headers and quality tune, plus the plenum, TB and labour which will no doubt include drilling the heads as all the manifold bolts will be knobs of rust) won't be cheap. Suggest the overall cost will get you a decent chunk of the way to a gen two 3.4 which definitely has more power and torque across the rev range (albeit not dramatic amount more) and is more reliable. And of course will be a few years less old and a few years further away from rotting. Otherwise, find a gen one with a scored engine and get it 3.9'ed at Hartech. But I would think the option which makes least sense in the end is buying a gen one 3.4 and chucking a load of money at it with no guarantees you'll get good results. And unless it's been rebuilt already (and properly), the M97 3.4 is so very score prone it makes the idea of pouring money into one pretty unappealing, no? If you've got the patience and can find the right car, a rebuilt gen one to 3.9 is a nice idea. The only issue is cost. It's probably in the region of £20k these days to get the engine taken out to 3.9 at Hartech and then you've got a car that's tricky to value if resale is a concern. Which brings you back to the gen two again. Final budget approach might be this. Find a gen one 3.4 that's already been rebuilt by Hartech. They don't seem to trade for a huge amount more than a good non-rebuilt car. Then grab a pair of used 987 3.2 factory headers if you can find some. They are supposedly much better than the 3.4 headers, which I can believe as the 3.4 headers look particularly rubbish and restrictive. Don't bother with the TB and the plenum. Just get a remap. That will probably get you most of the likely power gains for far less money. But even as I say that I tend to think you're still not going to be huge distance off gen two money and you won't get the money back on any of that work you've had done at resale. So, if you want a bit more power than the gen one, arguably all roads lead to the gen two.

Also FYI I don't think a bigger throttle body or ipd will do much. Maybe a few hp extra with all the other mods but the torque is more important. Not worth it for £1500 imo.

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 I know I will get panned and people say not real but used to have the 3.4 spyder and feels right in the middle of the base car and the spyder. Exactly right for me for a fun daily on the road. If you open up a stock 987 exhaust you will see essentially a metal wall which blocks all the exhaust gases coming out. Insane how much it's restricted. Then look the Manifolds and cats with all the crushes. The throttle also doesn't open fully on these hence the remap let's it open in a linear fashion. 3mpg better on my like for like driving as well which is ace and can now massage 500 miles out of a tank on a long run. Do it I would say. Nothing you will ever regret. Graph below is curve and power (in hp and lb/ft)with Manifolds and exhaust fitted. Picked up torque but lost a bit of power due to fuelling being rich. After remap it's smoothed it all out. Equal length tubing helps a bunch. Edited by jayxx83 on Wednesday 6th March 21:44

Hi. I’ve tried and agree with others…you’re not going to get 50bhp. My modded 987s was a cracker. - PARR rebuilt the engine. - top gear stainless manifolds with 200cel cats - carnewal back box - bc filter and de snork The manifolds and filter made a noticeable difference from the seat in that the car felt more responsive and less strangled, ( plus sounded fantastic ). I then fitted an IPD plenum and gt3 throttle body but tbh it felt worse on the road. I then rang Wayne to book it in for mapping and , ( from memory ), he said he wasn’t surprised as he doesn’t see gains from this mod as the ecu is pretty locked down so can’t be adjusted to manage the increased airflow.. As a result I took the kit off and sent it back.. I still took it to Wayne but he pre warned me he was unlikely to be able to find much gain..He found a few more bhp but mainly by finding some disconnected vacuum pipes etc.. From memory it was producing about 300bhp so barely anything over standard.. I later fitted a lightweight flywheel which generally made it feel a bit more lively but hill starts became a bit tricky.. I also fitted a Wavetrac LSD which probably turned out to be a mistake. It was a road car and I’d read all the info on the Wavetrac and the claims that’s its design meant it didn’t lead to increased under steer however I felt it did at least a small amount at turn in and just generally felt less neutral right at that point.. It poss would have been well worth it on track if the benefits outweighed this but I never got around to getting on track.. So based on my experience I’d do the filter/manifolds/exhaust/LWFW and not bother with much else.. If you’ve got the budget though I would 100% spend it on KWV3 suspension or something similarly good. I thought they were fabulous… If you have the money and don’t mind not getting a return on it then a Hartech big engine would be the way to go. I contemplated it but couldn’t justify it. The other option at half the cost and with much bigger gains is the MNR twin turbo conversion. Not sure how many have been done or how well proven it is yet but obviously it will change the feel and nature of the car considerably and tbh I didn’t want to loose the balanced NA character of mine.. Good luck with whichever way you go but preppared for small gains at comparatively big outlay if you try the tuning route rather than big capacity or forced induction.. Edited by Edmundo2 on Friday 8th March 22:35

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 I know I will get panned and people say not real but used to have the 3.4 spyder and feels right in the middle of the base car and the spyder. Exactly right for me for a fun daily on the road. If you open up a stock 987 exhaust you will see essentially a metal wall which blocks all the exhaust gases coming out. Insane how much it's restricted. Then look the Manifolds and cats with all the crushes. The throttle also doesn't open fully on these hence the remap let's it open in a linear fashion. 3mpg better on my like for like driving as well which is ace and can now massage 500 miles out of a tank on a long run. Do it I would say. Nothing you will ever regret. Graph below is curve and power (in hp and lb/ft)with Manifolds and exhaust fitted. Picked up torque but lost a bit of power due to fuelling being rich. After remap it's smoothed it all out. Equal length tubing helps a bunch. M&M exhausts are excellent, (Manthey used them on their 996 GT3 conversions to brilliant effect) but I’m dubious they’re that good. If they did produce those sort of numbers they would be THE default system bolted on to every 2,9 and 3.4 Gen 1 Cayman and Boxster by owners looking for power increases. What type of dyno was the car tested on ? And whose dyno was it ?

Thanks for all the posts folks. I swapped the 996.1 for the Cayman S today. Really incredible how different they are - who knew, etc - and I think I'll start with getting the most out of what is there already. Some sort of suspension work is on the cards for the future, I'll make sure the alignment is spot on first.

Love to hear it! Yeah. They need precise suspension. I got beaten half way through my swap to Cayman R shocks and springs today! I honestly don't think they need more power. They're already so capable that they're too fast for the road if you go deep into the throttle for any length of time. They just need to be in good shape and well driven!

Nice one. Decent coil overs and adjustable toe arms allowing you to run R geo is a good bet + decent pads and brake lines etc.. That coupled with some more noise, a quick shift and some more supportive seats will make a real difference, ( Cobra Nogaros are worth a look ). The power chase is seemingly pretty futile so better to improve the other aspects.

Edmundo2 said: Nice one. Decent coil overs and adjustable toe arms allowing you to run R geo is a good bet + decent pads and brake lines etc.. That coupled with some more noise, a quick shift and some more supportive seats will make a real difference, ( Cobra Nogaros are worth a look ). The power chase is seemingly pretty futile so better to improve the other aspects. Yeah I've got Cayman R toe arms, I'm getting a Quaife LSD put in next month. I already have a Milltek exhaust which I love. Interior may be next year's job. I keep looking longingly at recaro buckets but I have a blue interior which makes finding something matching pretty hard.

Nice one. Decent coil overs and adjustable toe arms allowing you to run R geo is a good bet + decent pads and brake lines etc.. That coupled with some more noise, a quick shift and some more supportive seats will make a real difference, ( Cobra Nogaros are worth a look ). The power chase is seemingly pretty futile so better to improve the other aspects.

Slippydiff said: M&M exhausts are excellent, (Manthey used them on their 996 GT3 conversions to brilliant effect) but I’m dubious they’re that good. If they did produce those sort of numbers they would be THE default system bolted on to every 2,9 and 3.4 Gen 1 Cayman and Boxster by owners looking for power increases. What type of dyno was the car tested on ? And whose dyno was it ? TBH the £6-7k cost of the exhaust probably would put most people off hence why most dont do it. I got an insane bargain in covid 2020. i was going to pull the trigger on a new one but then searched German Gumtree and found this for £775 delivered to the UK. It was fitted by Parr in Crawley with some nuts and bolts. Lucky no studs broke in the head. https://www.fvd.net/de-en/BES98720201S/street-exha... https://www.fvd.net/de-en/FVD98761870MG/fvd-softwa... The exhausts and mani gives a big bump even with out the map and 30 hp is pretty much spot on what I achieved without the map the fitting was around 1k however due to a bit of welding needed on the exhaust. It's been as good as gold however since fitting 4 years ago. The tune was done by GAD tuning in Essex. I wanted a live map opposed to a canned tune and a neighbour has an RS60 and just got the map done on his standard car and said it ran so much smoother with the flat spot eliminated at 3-4k. I was recommended to them by Copse Automotive in Woking who run a load of 986 and 987/997 race cars and David there wasn't surprised by the results at all. That is a before and after dyno done the same day. David used to work at Parr I believe. TBH my aim when I got this car was just to unlock it in the areas Porsche had held it back. Wasn't concerned if it was 250 or 350 bhp, just love the balance of the 2.9 and wanted all the marketing hold backs removed. It's so smooth through the rev range for what it is and so sharp above 4k now. I'm awaiting the car back in a week or two as it has just had full poly bushing all around in new coffin arms, new top mounts, triangle arms, rebuilt Ohlins, Boxster Spyder ARB, poly engine mount and setting up again. It was insane when set up by Copse just on the corner balance and their fast road alignment. God only knows that it will feel like with all the refresh done. The car only has 44k miles and know the suspension stuff didn't really need doing but the Ohlins needed a rebuild as the damping was all but done with 30k miles of use so thought may as well. Probably spent almost spent the same on mods as I have to buy the car but its such a pocket rocket and gives you more than a hot hatch does. Roll on the summer.

jayxx83 said: TBH the £6-7k cost of the exhaust probably would put most people off hence why most dont do it. I got an insane bargain in covid 2020. i was going to pull the trigger on a new one but then searched German Gumtree and found this for £775 delivered to the UK. It was fitted by Parr in Crawley with some nuts and bolts. Lucky no studs broke in the head. https://www.fvd.net/de-en/BES98720201S/street-exha... https://www.fvd.net/de-en/FVD98761870MG/fvd-softwa... The exhausts and mani gives a big bump even with out the map and 30 hp is pretty much spot on what I achieved without the map the fitting was around 1k however due to a bit of welding needed on the exhaust. It's been as good as gold however since fitting 4 years ago. The tune was done by GAD tuning in Essex. I wanted a live map opposed to a canned tune and a neighbour has an RS60 and just got the map done on his standard car and said it ran so much smoother with the flat spot eliminated at 3-4k. I was recommended to them by Copse Automotive in Woking who run a load of 986 and 987/997 race cars and David there wasn't surprised by the results at all. That is a before and after dyno done the same day. David used to work at Parr I believe. TBH my aim when I got this car was just to unlock it in the areas Porsche had held it back. Wasn't concerned if it was 250 or 350 bhp, just love the balance of the 2.9 and wanted all the marketing hold backs removed. It's so smooth through the rev range for what it is and so sharp above 4k now. I'm awaiting the car back in a week or two as it has just had full poly bushing all around in new coffin arms, new top mounts, triangle arms, rebuilt Ohlins, Boxster Spyder ARB, poly engine mount and setting up again. It was insane when set up by Copse just on the corner balance and their fast road alignment. God only knows that it will feel like with all the refresh done. The car only has 44k miles and know the suspension stuff didn't really need doing but the Ohlins needed a rebuild as the damping was all but done with 30k miles of use so thought may as well. Probably spent almost spent the same on mods as I have to buy the car but its such a pocket rocket and gives you more than a hot hatch does. Roll on the summer. Yep, they’re not cheap, but they’re one of the few manufacturers whose products genuinely produce worthwhile power increases. The complete M&M exhaust on a 996.1 GT3 produces an additional 35hp albeit with a remap. It frees up the engine’s ability to breath and rev above 5000rpm to 8000/8100rpm. Agree totally with your comments on a live remap over a canned map. I’ve recently fitted Ohlins R&T’s to my 996.2. Still optimising their settings, but initial impressions are hugely impressive.

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?

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.

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.

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.