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400 hp from a 997.1 C4S: What's the cheapest way?


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Yes, Road & Track Tested a stock 2005 997S and reported 0-60 time of 3.9 sec., but the 1/4 mile was about 12.8 @ 110 as I recall.

I have not dyno'd my car but my track time comparison is better and the acceleration differences are significant as follows:

Stock 997S

0-60 best time = 4.1

1/4 mile best time = 12.9 @ 111.9

Modified 997S

0-60 best time = 3.9

1/4 mile best time 12.2 @116

To answer the question about the X - 51 throttle body, the base attachment is exactly the same as a stock 997S TB, so no modifications are required. The intake is larger. You can use a stock TB with the X-51 air box, but it requires a "bushing" at the rubber to TB connection.

Wayne

Wayne could you post a pic of the throttle body connected to the intake...I have been told countless times that it would not fit the stock intake distributor and a few times it will fit. It's not that I don't believe you I just want to show it to the naysayers.

Dave

I have a friend with an 05 997 S. He is putting the X 51 throttle body on and was told by his tuner he has to replace the manifolds as well because of the difference in diameter.

I would like to see a picture too!! Is it that it will fit the stock manifold but will work better with the X 51 manifold?

Thanks!

There are other issues as well if you change the manifolds such as the butterfly valve in the OEM manifold..that's part of the software update of the X51. To be honest..I don't believe him until I see it.

Another thing...the R&T article had the non X51 S run a 3.9 0-60 and a 12.3 @114.8mph...my best Jim Carrery impression "SMOKIN!!"

Dave

Edited by Dave07997S
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Dave,

You were correct about the Road & Track article 1/4 mile time. I was basing the timing et on my "recall" which apparently was not exact.

However, the X-51 TB will work on the existing 997S intake manifolds without modification to the TB or stock intake manifolds. The TB connects directly to a plastic intake distribution tube (Plenum). You have to use a RSS IPD Plenum that has been adapted to fit the stock X51 TB. This is not a big deal.

Wayne

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Dave,

You were correct about the Road & Track article 1/4 mile time. I was basing the timing et on my "recall" which apparently was not exact.

However, the X-51 TB will work on the existing 997S intake manifolds without modification to the TB or stock intake manifolds. The TB connects directly to a plastic intake distribution tube (Plenum). You have to use a RSS IPD Plenum that has been adapted to fit the stock X51 TB. This is not a big deal.

Wayne

Wayne did you modify an existing RSS IPD plenum as Greg says he doesn't produce one. It can be easily be done though I guess.

Dave

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Yes I had the existing RSS IPD modified. I recommend a good machine shop unless you have the tools and the talent.

Wayne

Wayne, where do you live...I am in Los Angeles. I figure the existing RSS plenum probably just has to have the hole enlargened as well as the old screw holes filled and new ones drilled. Is this about it??

Dave

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I live near Louisville Ky. I don't know exactly what was done to modify the RSS plenum. (I did not see the part until after the modification, and the fit was perfect.) I do know that it took a bit of machine shop work to make the fit. I did not want to modify any stock parts on my 997S (ie manifolds or X51 TB) and the stock plastic plenum was not a ggod choice for machining. The stock RSS was suggested because it was metal and could be easily modified.

Wayne

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I live near Louisville Ky. I don't know exactly what was done to modify the RSS plenum. (I did not see the part until after the modification, and the fit was perfect.) I do know that it took a bit of machine shop work to make the fit. I did not want to modify any stock parts on my 997S (ie manifolds or X51 TB) and the stock plastic plenum was not a ggod choice for machining. The stock RSS was suggested because it was metal and could be easily modified.

Wayne

Thanks Wayne...

I talked to RSS, they did testing with the X51 TB with thier plenum and found 3-4rwhp more than the stock TB. I feel it's worth it.

Dave

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Wayne,

When you had the RSS Plenum modified did you give the maching shop the specs? Or did you just give them the TB and the plenum and tell them what you wanted done?

Also Dave.. I'm in Los Angeles as well and would like to follow your process if you go the same route

Thanks!

Edited by phillipj
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Thanks Dave. It's good to know my "seat of the pants" dyno was not incorrect. I agree the X51 TB with the modified RSS Plenum is the best way to make the X51 airbox + X51 TB work.

Phillip, I was not aware of the RSS option when I was putting the parts together. I took my stock plastic plenum in the shop and told them I wanted the X51 to match my plastic plenum. The shop guys suggested I use the RSS plenum.

I agreed to the recommendation and they got the parts and machined it to work. I just picked up the machined RSS part and assembled everything back together!

The only other alternate is to use the stock 997S TB with a "rubber bushing" to mate up the the X51 airbox.

With the mods I have made: X51 Air Box, X51TB, Fabspeed Headers, Fabspeed Mufflers, I am very satisfied with the results. (Maybe not 400 HP, but a lot more than 355.) The car has great acceleration and the track time has greatly improved! (Unfortunately not my driving skills.)

Wayne

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Wayne,

When you had the RSS Plenum modified did you give the maching shop the specs? Or did you just give them the TB and the plenum and tell them what you wanted done?

Also Dave.. I'm in Los Angeles as well and would like to follow your process if you go the same route

Thanks!

Phillip, we should stay in touch and maybe Greg ar RSS will give us a deal. He can machine the plenum for us but he wants $300 to do it. Sounds a tad high.

Dave

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Hi;

I have considered all options for performance. (I don't like turbo, and superchargers/ chips void your warranty.)

I really prefer both the sound and response of naturally aspirated engines.

I have a 2008 997S and have been very successful with HP/ performance gains by adding the following: 1)Fabspeed headers/ mufflers, 2)X-51 Carbon Fiber Airbox with new X-51 throttle body, 3)BMC air filters.

You can do all of this for about $5K if you do the install yourself.

I have not dyno'ed the changes but can guarantee you will be satisfied with the "seat of the pants" test. I have road tested by comparing to the new 997-2 (385HP) and smoked the new 997 in both 1/4 mile and track time.

0-60 times are 3.9 sec., 1/4 mile 12.2@116mph. (This is pretty darn close to GT3 specs.)

This would be my recommendation for HP/ Performance enhancements.

Wayne

Wayne, I see that you have BMC air filters for you X51 carbon airbox. Where did you get this and do you have a part #? Some people report troube with their MAF after installing KN + BMC airfilters. Have you noticed any problem?

Thanks.

Frank

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Frank,

I got the filters at FVD Brombacher. (954) 571 2050. Ask for Rhonda.

The part No. is 470 468 20 BMC Sport Air Filter 977 X51.

I have never had a problem with them. Just don't over oil them. (They come pre oiled and are just right from the factory.)

I would recommend them over the stock X51 filters for both quality and performance.

Wayne

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Frank,

I got the filters at FVD Brombacher. (954) 571 2050. Ask for Rhonda.

The part No. is 470 468 20 BMC Sport Air Filter 977 X51.

I have never had a problem with them. Just don't over oil them. (They come pre oiled and are just right from the factory.)

I would recommend them over the stock X51 filters for both quality and performance.

Wayne

Wayne,

Thanks for you help. I will order on monday.

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There really is some utter cr*p talked about how to get power from a naturally aspirated engine - especially regarding how much is available from bolt-on mods. I think it's about time we discussed what does and doesn't work on these engines....

The 3.8 engine in stock tune produces 93.4BHP/litre. Not stellar by today's standards but still high enough that there's not a lot of 'low-hanging fruit' to be had. Also bear in mind that most engines that do a lot better are either forced induction or (more importantly to this discussion) rev much higher. The max BHP obtainable from an engine increases dramatically with more rpm (assuming the rest of the engine is engineered with the higher rpms in mind). Unfortunately, the 997S engine cannot be revved higher - it explodes. So 93.4BHP/litre is a good result for an engine that only revs to 7300rpm.

So what can be done. Well let's address the OP's question. There are 2 ways to get 400BHP from this engine without forced induction. The first is to have the capacity increased to 4-litres plus, the other is to start with the X-51 engine (the factory 381BHP upgrade). You simply cannot get the stock 355BHP engine to 400BHP. Period.

So what works on these engines? Well sorry guys but here's the absolute truth:

1) Induction kits. These have no proven effect whatsoever apart from noise. The standard airbox is very, very good and keeps intake air temps in check very well. A BMC-F1 panel filter is good for 3-4BHP but doesn't filter as well as the paper one. Your choice.

2) Plenums. Just don't go there. There were hundreds of discussions on 6-speed over these and eventually a lot of third party dynos. Trick plenums lose power in the mid band and give no gains elsewhere. (I bought one, installed it, found a performance loss, removed it and wasted my money so I'm well-placed to comment)!!

3) Exhausts. On the 3.8, the dire-looking pressed steel headers are far better than they look. The work well at low/mid rpm and only very slightly strangle the engine at high rpms. Good quality headers will give 6-7BHP in conjunction with a full exhaust system but only over 5000rpm. You may also lose some low and mid-band torque. The stock mufflers again flow very well and replacing these alone will give little to no gain (5BHP max). The standard catalytic converters however are very restrictive and a good pair of 200-cell cats will give 15-20BHP on this engine. The best solution is a good, matched system (headers, cats, mufflers) that will give 25BHP or so. Nobody has ever (to my knowledge) got to the +40BHP claimed by certain exhaust manufacturers.

4) Re-maps. This is so hit and miss. What does a remap do? Simply, it can alter the mixture or ignition timing at different operating phases of the engine. The standard Porsche maps are designed to run 98-RON (93-PON?) fuel and fuel the engine more or less optimally for max power so there is almost nowhere to go for a stock engine (despite the claims). Blindly adding-in timing (as some generic maps do) will just cause the knock sensors to wind it out again and the whole car will run dreadfully. Unfortunately some 'tuners' just alter the throttle mapping to give the illusion of more part-throttle power - naughty! The time when re-maps DO work is with other mods. Change the hardware (e.g a full exhaust) and you have changed the engine's volumetric efficiency at certain rpms. This usually requires the ignition timing to be changed by a few degrees to work optimally at those rpms and extra power will result, but it's very unlikely to be more than single digits.

So with a stock engine, a full exhaust, custom remap and BMC filter can give +30-35BHP (crank) and this is as far as this goes without very extensive further internal and external modifications to the engine.

The X-51 engine is a different beast however. Totally different intake system, bigger throttle body, high-flow airbox, gas-flowed heads, different exhaust headers and electronics mapped to suit make this a much better platform. This engine retains the stock catalytic converters that are now more restrictive than ever and a full exhaust on this motor will give you 25-30BHP with no trouble. There's your 400+BHP.

If you want 400+ BHP with massive torque, look at 9ff (German Tuner)'s large capacity, crated engines. Expensive, but will give you the fastest 997S out there.

When all is said and done however, to get 400+ BHP is so expensive that you could have one of the better cars Porsche already makes with 400+ BHP out the box (GT3 anyone). A full exhaust, remap and BMC filter combination however, is sensible money and makes the 997S go and sound like it should whilst giving 385-390BHP on a good engine. This would be my preferred route.

Edited by ianwallwork
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Great information. Interesting about the plenum though.... I put a plenum on my 99 3.4 C2 and noticed a dramatic difference in power at 5000 rpm. At the same time my friend with a 2005 C2S coupe installed the plenum and got reduced performance..

Thanks for explanation about the X 51 and other details. Great write up!

Phillipj

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Great information. Interesting about the plenum though.... I put a plenum on my 99 3.4 C2 and noticed a dramatic difference in power at 5000 rpm. At the same time my friend with a 2005 C2S coupe installed the plenum and got reduced performance..

Thanks for explanation about the X 51 and other details. Great write up!

Phillipj

That is interesting about the plenum. The 3.4 is a very different engine to the 3.8 and as such will have totally different intake characteristics. Maybe this engine responds well to the changed flow patterns the plenum causes in the induction system whereas the 3.8 seems not to. I'd be intrigued to see some dyno plots on this one.

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There really is some utter cr*p talked about how to get power from a naturally aspirated engine - especially regarding how much is available from bolt-on mods. I think it's about time we discussed what does and doesn't work on these engines....

The 3.8 engine in stock tune produces 93.4BHP/litre. Not stellar by today's standards but still high enough that there's not a lot of 'low-hanging fruit' to be had. Also bear in mind that most engines that do a lot better are either forced induction or (more importantly to this discussion) rev much higher. The max BHP obtainable from an engine increases dramatically with more rpm (assuming the rest of the engine is engineered with the higher rpms in mind). Unfortunately, the 997S engine cannot be revved higher - it explodes. So 93.4BHP/litre is a good result for an engine that only revs to 7300rpm.

So what can be done. Well let's address the OP's question. There are 2 ways to get 400BHP from this engine without forced induction. The first is to have the capacity increased to 4-litres plus, the other is to start with the X-51 engine (the factory 381BHP upgrade). You simply cannot get the stock 355BHP engine to 400BHP. Period.

So what works on these engines? Well sorry guys but here's the absolute truth:

1) Induction kits. These have no proven effect whatsoever apart from noise. The standard airbox is very, very good and keeps intake air temps in check very well. A BMC-F1 panel filter is good for 3-4BHP but doesn't filter as well as the paper one. Your choice.

2) Plenums. Just don't go there. There were hundreds of discussions on 6-speed over these and eventually a lot of third party dynos. Trick plenums lose power in the mid band and give no gains elsewhere. (I bought one, installed it, found a performance loss, removed it and wasted my money so I'm well-placed to comment)!!

3) Exhausts. On the 3.8, the dire-looking pressed steel headers are far better than they look. The work well at low/mid rpm and only very slightly strangle the engine at high rpms. Good quality headers will give 6-7BHP in conjunction with a full exhaust system but only over 5000rpm. You may also lose some low and mid-band torque. The stock mufflers again flow very well and replacing these alone will give little to no gain (5BHP max). The standard catalytic converters however are very restrictive and a good pair of 200-cell cats will give 15-20BHP on this engine. The best solution is a good, matched system (headers, cats, mufflers) that will give 25BHP or so. Nobody has ever (to my knowledge) got to the +40BHP claimed by certain exhaust manufacturers.

4) Re-maps. This is so hit and miss. What does a remap do? Simply, it can alter the mixture or ignition timing at different operating phases of the engine. The standard Porsche maps are designed to run 98-RON (93-PON?) fuel and fuel the engine more or less optimally for max power so there is almost nowhere to go for a stock engine (despite the claims). Blindly adding-in timing (as some generic maps do) will just cause the knock sensors to wind it out again and the whole car will run dreadfully. Unfortunately some 'tuners' just alter the throttle mapping to give the illusion of more part-throttle power - naughty! The time when re-maps DO work is with other mods. Change the hardware (e.g a full exhaust) and you have changed the engine's volumetric efficiency at certain rpms. This usually requires the ignition timing to be changed by a few degrees to work optimally at those rpms and extra power will result, but it's very unlikely to be more than single digits.

So with a stock engine, a full exhaust, custom remap and BMC filter can give +30-35BHP (crank) and this is as far as this goes without very extensive further internal and external modifications to the engine.

The X-51 engine is a different beast however. Totally different intake system, bigger throttle body, high-flow airbox, gas-flowed heads, different exhaust headers and electronics mapped to suit make this a much better platform. This engine retains the stock catalytic converters that are now more restrictive than ever and a full exhaust on this motor will give you 25-30BHP with no trouble. There's your 400+BHP.

If you want 400+ BHP with massive torque, look at 9ff (German Tuner)'s large capacity, crated engines. Expensive, but will give you the fastest 997S out there.

When all is said and done however, to get 400+ BHP is so expensive that you could have one of the better cars Porsche already makes with 400+ BHP out the box (GT3 anyone). A full exhaust, remap and BMC filter combination however, is sensible money and makes the 997S go and sound like it should whilst giving 385-390BHP on a good engine. This would be my preferred route.

Ian, glad to see you here as well and always look forward to your input. However, the X51 heads from my understanding are nothing more than some bowl work and a stiffer exhaust valve for the increased rpm to 7450rpm. The stock non X51 heads have to flow pretty darn good to get to 93hp/litre while limiting rpm to 7300rpm. In my own experience heads without updated cams and more rpm is probably at best 5-10rwhp and in my opinion are a total waste of money for what Porsche wants for the X51 heads. You layed out a good plan for getting the hp to at least X51 levels with only half or less of the expense. Obviously if you start with more power you will end up with more power. On 6speed we discussed that I was considering the intake manifolds from the X51 and I have to be honest, from the people I talked to I figured it wasn't worth the expense (as you thought) of going down this road for what will at best be 10rwhp for the huge expense. I will still do the X51 carborn air box as I think it is so pretty and really is not a bad investment for what it costs (a lot cheaper than some of the non OEM intakes out there) and only having to deal with cutting out the upper deck lid for the other inlet.

Dave

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There really is some utter cr*p talked about how to get power from a naturally aspirated engine - especially regarding how much is available from bolt-on mods. I think it's about time we discussed what does and doesn't work on these engines....

The 3.8 engine in stock tune produces 93.4BHP/litre. Not stellar by today's standards but still high enough that there's not a lot of 'low-hanging fruit' to be had. Also bear in mind that most engines that do a lot better are either forced induction or (more importantly to this discussion) rev much higher. The max BHP obtainable from an engine increases dramatically with more rpm (assuming the rest of the engine is engineered with the higher rpms in mind). Unfortunately, the 997S engine cannot be revved higher - it explodes. So 93.4BHP/litre is a good result for an engine that only revs to 7300rpm.

So what can be done. Well let's address the OP's question. There are 2 ways to get 400BHP from this engine without forced induction. The first is to have the capacity increased to 4-litres plus, the other is to start with the X-51 engine (the factory 381BHP upgrade). You simply cannot get the stock 355BHP engine to 400BHP. Period.

So what works on these engines? Well sorry guys but here's the absolute truth:

1) Induction kits. These have no proven effect whatsoever apart from noise. The standard airbox is very, very good and keeps intake air temps in check very well. A BMC-F1 panel filter is good for 3-4BHP but doesn't filter as well as the paper one. Your choice.

2) Plenums. Just don't go there. There were hundreds of discussions on 6-speed over these and eventually a lot of third party dynos. Trick plenums lose power in the mid band and give no gains elsewhere. (I bought one, installed it, found a performance loss, removed it and wasted my money so I'm well-placed to comment)!!

3) Exhausts. On the 3.8, the dire-looking pressed steel headers are far better than they look. The work well at low/mid rpm and only very slightly strangle the engine at high rpms. Good quality headers will give 6-7BHP in conjunction with a full exhaust system but only over 5000rpm. You may also lose some low and mid-band torque. The stock mufflers again flow very well and replacing these alone will give little to no gain (5BHP max). The standard catalytic converters however are very restrictive and a good pair of 200-cell cats will give 15-20BHP on this engine. The best solution is a good, matched system (headers, cats, mufflers) that will give 25BHP or so. Nobody has ever (to my knowledge) got to the +40BHP claimed by certain exhaust manufacturers.

4) Re-maps. This is so hit and miss. What does a remap do? Simply, it can alter the mixture or ignition timing at different operating phases of the engine. The standard Porsche maps are designed to run 98-RON (93-PON?) fuel and fuel the engine more or less optimally for max power so there is almost nowhere to go for a stock engine (despite the claims). Blindly adding-in timing (as some generic maps do) will just cause the knock sensors to wind it out again and the whole car will run dreadfully. Unfortunately some 'tuners' just alter the throttle mapping to give the illusion of more part-throttle power - naughty! The time when re-maps DO work is with other mods. Change the hardware (e.g a full exhaust) and you have changed the engine's volumetric efficiency at certain rpms. This usually requires the ignition timing to be changed by a few degrees to work optimally at those rpms and extra power will result, but it's very unlikely to be more than single digits.

So with a stock engine, a full exhaust, custom remap and BMC filter can give +30-35BHP (crank) and this is as far as this goes without very extensive further internal and external modifications to the engine.

The X-51 engine is a different beast however. Totally different intake system, bigger throttle body, high-flow airbox, gas-flowed heads, different exhaust headers and electronics mapped to suit make this a much better platform. This engine retains the stock catalytic converters that are now more restrictive than ever and a full exhaust on this motor will give you 25-30BHP with no trouble. There's your 400+BHP.

If you want 400+ BHP with massive torque, look at 9ff (German Tuner)'s large capacity, crated engines. Expensive, but will give you the fastest 997S out there.

When all is said and done however, to get 400+ BHP is so expensive that you could have one of the better cars Porsche already makes with 400+ BHP out the box (GT3 anyone). A full exhaust, remap and BMC filter combination however, is sensible money and makes the 997S go and sound like it should whilst giving 385-390BHP on a good engine. This would be my preferred route.

Ian, glad to see you here as well and always look forward to your input. However, the X51 heads from my understanding are nothing more than some bowl work and a stiffer exhaust valve for the increased rpm to 7450rpm. The stock non X51 heads have to flow pretty darn good to get to 93hp/litre while limiting rpm to 7300rpm. In my own experience heads without updated cams and more rpm is probably at best 5-10rwhp and in my opinion are a total waste of money for what Porsche wants for the X51 heads. You layed out a good plan for getting the hp to at least X51 levels with only half or less of the expense. Obviously if you start with more power you will end up with more power. On 6speed we discussed that I was considering the intake manifolds from the X51 and I have to be honest, from the people I talked to I figured it wasn't worth the expense (as you thought) of going down this road for what will at best be 10rwhp for the huge expense. I will still do the X51 carborn air box as I think it is so pretty and really is not a bad investment for what it costs (a lot cheaper than some of the non OEM intakes out there) and only having to deal with cutting out the upper deck lid for the other inlet.

Dave

Dave - really good to see you on here too. This is one of the best forums on the 'net for Porsche owners and I wish more 6speeders would take the time to post (and contribute). I agree totally with your comments above - of all the intakes for the Mk1 997S, the X-51 is probably the best. However..... I've mailed Fabspeed today to beg them to produce a version of their (superb) high performance intake (that they only provide for 997S/2 currently) for the 997S/1. I'll be posting on 6speed about this soon too. Their new intake is the best I've ever seen and I think all us addicted modifiers would snap it up for our Mk1's!

See you on 6speed again soon.

Ian

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There really is some utter cr*p talked about how to get power from a naturally aspirated engine - especially regarding how much is available from bolt-on mods. I think it's about time we discussed what does and doesn't work on these engines....

The 3.8 engine in stock tune produces 93.4BHP/litre. Not stellar by today's standards but still high enough that there's not a lot of 'low-hanging fruit' to be had. Also bear in mind that most engines that do a lot better are either forced induction or (more importantly to this discussion) rev much higher. The max BHP obtainable from an engine increases dramatically with more rpm (assuming the rest of the engine is engineered with the higher rpms in mind). Unfortunately, the 997S engine cannot be revved higher - it explodes. So 93.4BHP/litre is a good result for an engine that only revs to 7300rpm.

So what can be done. Well let's address the OP's question. There are 2 ways to get 400BHP from this engine without forced induction. The first is to have the capacity increased to 4-litres plus, the other is to start with the X-51 engine (the factory 381BHP upgrade). You simply cannot get the stock 355BHP engine to 400BHP. Period.

So what works on these engines? Well sorry guys but here's the absolute truth:

1) Induction kits. These have no proven effect whatsoever apart from noise. The standard airbox is very, very good and keeps intake air temps in check very well. A BMC-F1 panel filter is good for 3-4BHP but doesn't filter as well as the paper one. Your choice.

2) Plenums. Just don't go there. There were hundreds of discussions on 6-speed over these and eventually a lot of third party dynos. Trick plenums lose power in the mid band and give no gains elsewhere. (I bought one, installed it, found a performance loss, removed it and wasted my money so I'm well-placed to comment)!!

3) Exhausts. On the 3.8, the dire-looking pressed steel headers are far better than they look. The work well at low/mid rpm and only very slightly strangle the engine at high rpms. Good quality headers will give 6-7BHP in conjunction with a full exhaust system but only over 5000rpm. You may also lose some low and mid-band torque. The stock mufflers again flow very well and replacing these alone will give little to no gain (5BHP max). The standard catalytic converters however are very restrictive and a good pair of 200-cell cats will give 15-20BHP on this engine. The best solution is a good, matched system (headers, cats, mufflers) that will give 25BHP or so. Nobody has ever (to my knowledge) got to the +40BHP claimed by certain exhaust manufacturers.

4) Re-maps. This is so hit and miss. What does a remap do? Simply, it can alter the mixture or ignition timing at different operating phases of the engine. The standard Porsche maps are designed to run 98-RON (93-PON?) fuel and fuel the engine more or less optimally for max power so there is almost nowhere to go for a stock engine (despite the claims). Blindly adding-in timing (as some generic maps do) will just cause the knock sensors to wind it out again and the whole car will run dreadfully. Unfortunately some 'tuners' just alter the throttle mapping to give the illusion of more part-throttle power - naughty! The time when re-maps DO work is with other mods. Change the hardware (e.g a full exhaust) and you have changed the engine's volumetric efficiency at certain rpms. This usually requires the ignition timing to be changed by a few degrees to work optimally at those rpms and extra power will result, but it's very unlikely to be more than single digits.

So with a stock engine, a full exhaust, custom remap and BMC filter can give +30-35BHP (crank) and this is as far as this goes without very extensive further internal and external modifications to the engine.

The X-51 engine is a different beast however. Totally different intake system, bigger throttle body, high-flow airbox, gas-flowed heads, different exhaust headers and electronics mapped to suit make this a much better platform. This engine retains the stock catalytic converters that are now more restrictive than ever and a full exhaust on this motor will give you 25-30BHP with no trouble. There's your 400+BHP.

If you want 400+ BHP with massive torque, look at 9ff (German Tuner)'s large capacity, crated engines. Expensive, but will give you the fastest 997S out there.

When all is said and done however, to get 400+ BHP is so expensive that you could have one of the better cars Porsche already makes with 400+ BHP out the box (GT3 anyone). A full exhaust, remap and BMC filter combination however, is sensible money and makes the 997S go and sound like it should whilst giving 385-390BHP on a good engine. This would be my preferred route.

Ian, glad to see you here as well and always look forward to your input. However, the X51 heads from my understanding are nothing more than some bowl work and a stiffer exhaust valve for the increased rpm to 7450rpm. The stock non X51 heads have to flow pretty darn good to get to 93hp/litre while limiting rpm to 7300rpm. In my own experience heads without updated cams and more rpm is probably at best 5-10rwhp and in my opinion are a total waste of money for what Porsche wants for the X51 heads. You layed out a good plan for getting the hp to at least X51 levels with only half or less of the expense. Obviously if you start with more power you will end up with more power. On 6speed we discussed that I was considering the intake manifolds from the X51 and I have to be honest, from the people I talked to I figured it wasn't worth the expense (as you thought) of going down this road for what will at best be 10rwhp for the huge expense. I will still do the X51 carborn air box as I think it is so pretty and really is not a bad investment for what it costs (a lot cheaper than some of the non OEM intakes out there) and only having to deal with cutting out the upper deck lid for the other inlet.

Dave

Dave - really good to see you on here too. This is one of the best forums on the 'net for Porsche owners and I wish more 6speeders would take the time to post (and contribute). I agree totally with your comments above - of all the intakes for the Mk1 997S, the X-51 is probably the best. However..... I've mailed Fabspeed today to beg them to produce a version of their (superb) high performance intake (that they only provide for 997S/2 currently) for the 997S/1. I'll be posting on 6speed about this soon too. Their new intake is the best I've ever seen and I think all us addicted modifiers would snap it up for our Mk1's!

See you on 6speed again soon.

Ian

You too Ian...

What software do you like?? After I do the intake I would like to do some software to tie it all together. I am leaning toward FVD, they are kind of expensive but the tweak to the numbers you email them. What's your thoughts??

Dave

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I'm having a custome remap done on 1st May. I think this is the best way to tie together any mods as the mapping , if done cirrectly, will work perfectly with the hardware on the car. It also takes into account the slight differences between production engines, the grade of fuel you use and (to a point) your driving style. The remap is being done by a UK tuner who does the mappings for most of the Porsche Chalenge Cup cars in the UK. They have a fantastic reputation and I can't see all the race teams going there year after year if they're not good at what they do. I'll be reporting back with dyno plots and results here and on 6-speed once it's done. I'm also hoping to gain a lot more knowledge of the inner workings of the engine control systems and will share everything I find out with other forum members both here and on 6-speed.

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I'm having a custome remap done on 1st May. I think this is the best way to tie together any mods as the mapping , if done cirrectly, will work perfectly with the hardware on the car. It also takes into account the slight differences between production engines, the grade of fuel you use and (to a point) your driving style. The remap is being done by a UK tuner who does the mappings for most of the Porsche Chalenge Cup cars in the UK. They have a fantastic reputation and I can't see all the race teams going there year after year if they're not good at what they do. I'll be reporting back with dyno plots and results here and on 6-speed once it's done. I'm also hoping to gain a lot more knowledge of the inner workings of the engine control systems and will share everything I find out with other forum members both here and on 6-speed.

Living in the UK as well I'm looking forward to your findings. Great write up btw.

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  • 1 month later...
Hi;

I have considered all options for performance. (I don't like turbo, and superchargers/ chips void your warranty.)

I really prefer both the sound and response of naturally aspirated engines.

I have a 2008 997S and have been very successful with HP/ performance gains by adding the following: 1)Fabspeed headers/ mufflers, 2)X-51 Carbon Fiber Airbox with new X-51 throttle body, 3)BMC air filters.

You can do all of this for about $5K if you do the install yourself.

I have not dyno'ed the changes but can guarantee you will be satisfied with the "seat of the pants" test. I have road tested by comparing to the new 997-2 (385HP) and smoked the new 997 in both 1/4 mile and track time.

0-60 times are 3.9 sec., 1/4 mile 12.2@116mph. (This is pretty darn close to GT3 specs.)

This would be my recommendation for HP/ Performance enhancements.

Wayne

Thanks for your input Wanye. I would love to see your dyno's. Also, did you do a "before" dyno when your car was stock?

Thanks,

Johnny

FWIW,

I agree with Wayne W.

I have added AWE HEADERSand CAts, REMUS Exhaust(AWE was too loud), X-51 Air box, RSS Plenum and Modified TB(not x-51), and APR software. Mine is a 6 speed but I have driven a 997.2 PDK in Sport mode and thought the engine was fantastic. Mine with the sport button on is every bit as good or better. I absolutely love the performance. The only thing I will do in the future is add lighter wheels and maybe a flywheel.

I prefer a N/A engine over a S/C and wouldn't consider that option.

Haven't tracked it but I had no problems staying with a Lambo and a Corvette on back roads while a 930 Turbo couldn't keep up.

David

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