Increasing HP in my Boxster S

[pdach]

I apologize if this question has already been addressed in a prior post.  I have been researching ways to increase the HP and Torque of my 2002 Boxster S.  There are a lot of various solutions from performance exhaust system to cold air injections system.  After speaking with my mechanic about this we concluded that more oxygen and/or more fuel to the engine is the most effective way to increase HP.  There are lots of forums on increasing HP but I have yet to see anything discussing replacing the fuel injector with an injector that injects more fuel.  This was my mechanic's best suggestion to gain more HP, please note that my mechanic does not specialize on working on Porsche’s, he does simple routine maintenance for me.  What are the pros and cons of replacing the existing fuel injector with an injector with higher fuel capacity?

[mikefocke]

Fooling around with air/fuel mixtures is a task for someone who really really understands the M96 engine. Change one variable and it can affect several others. Try for HP and you can change drive-ability. Keeping things in balance is what the hard task is and why an expert does it best.

 

A general catalog of possible mods is here. None that have a real effect are cheap. Figure $100 per HP.

 

And, BTW, every Boxster already has a cold air intake system in that air doesn't come from the hot engine compartment but from outside the car.

[JFP in PA]

Welcome to RennTech 

 

I can tell that your mechanic does not specialize in Porsches.  This is a topic that has been discussed many times, and a good search would help you fill in the details.

 

In a nutshell, cold air systems are a waste of time and money on these cars as it came from the factory with a very well designed one already installed.  Your current fuel injectors are capable of delivering more than enough fuel, so putting in larger ones is also a general waste of time and money.  They also won't add anything as the DME will step in and throttle them back to maintain the correct A/F ratios. The next big "fix" to produce more power are the aftermarket reflashes of the DME, which typically produce increases that fall with in statistical error range of the factory output on a dyno.  Larger throttle bodies and trick intake plenums also add little if anything on the dyno.  The best suggestion I would give to you is to remain very circumspect of performance gain claims you see in internet ads for companies that sell these mods; most are pretty much hot air.

 

So the question becomes how to get more power; the unfortunate answer is to spend a lot of money.  These engines are a system and need to be approached as such.  It is very possible to generate a lot of power, nearly twice the factory output, but it comes at a stiff price: Approaching $20K for a completely redone engine out of one of the premier M96 engine builders.

[Loren]

+1 on JFP's comments.

[ttocs]

Welcome!

 

FWIW: I would love to improve the performance of my 2004 Boxster Tip, but after hundreds of hours of fun and interesting reading - both good results and bad - from folks that have done all the different mods that are possible, I take my car out for a nice top-down drive and smile. Yes, I've had much quicker cars, shifter cars - although my left knee doesn't like clutches anymore, and cars that have amazing power and only go straight as well as cars that handle pretty well, and a smattering of motorcycles. But. No previous vehicle I've owned has provided me with as much FUN, that's FUN with a SMILE, as my slightly slow and very nimble little Boxster!! When I've thought about the investment necessary to increase the power, then compare that with simply buying a later version, I decided to enjoy and appreciate what I have.

 

I've experienced some thrills going to local PCA events and participating in some as well. Something as simple as a Porsche Driving Tour puts a smile on my face that lasts for days afterward!

 

just a few things I thought would be interesting to share . . .

[Stefan Pace]

On 4/23/2017 at 8:35 PM, JFP in PA said:

Welcome to RennTech 

 

I can tell that your mechanic does not specialize in Porsches.  This is a topic that has been discussed many times, and a good search would help you fill in the details.

 

In a nutshell, cold air systems are a waste of time and money on these cars as it came from the factory with a very well designed one already installed.  Your current fuel injectors are capable of delivering more than enough fuel, so putting in larger ones is also a general waste of time and money.  They also won't add anything as the DME will step in and throttle them back to maintain the correct A/F ratios. The next big "fix" to produce more power are the aftermarket reflashes of the DME, which typically produce increases that fall with in statistical error range of the factory output on a dyno.  Larger throttle bodies and trick intake plenums also add little if anything on the dyno.  The best suggestion I would give to you is to remain very circumspect of performance gain claims you see in internet ads for companies that sell these mods; most are pretty much hot air.

 

So the question becomes how to get more power; the unfortunate answer is to spend a lot of money.  These engines are a system and need to be approached as such.  It is very possible to generate a lot of power, nearly twice the factory output, but it comes at a stiff price: Approaching $20K for a completely redone engine out of one of the premier M96 engine builders.

 

Thanks for this post. Quick question on the torque capacity of the gearbox (G86.20): when you say "double the power is possible" - are are approaching 600Nm (440 ft-lbs) of torque. What is the torque limit of that G86.20 transaxle? I heard that this 6-speed is similar to the 911 unit but I have no information if that gearbox holds up.

 

Would greatly appreciate a reply.

 

[JFP in PA]

3 hours ago, Stefan Pace said:

 

Thanks for this post. Quick question on the torque capacity of the gearbox (G86.20): when you say "double the power is possible" - are are approaching 600Nm (440 ft-lbs) of torque. What is the torque limit of that G86.20 transaxle? I heard that this 6-speed is similar to the 911 unit but I have no information if that gearbox holds up.

 

Would greatly appreciate a reply.

 

 

I cannot give you a specific limit number, but I can tell you that putting in an engine with both high HP and torque, such as a Mezger turbo into a Boxster, decidedly exceeded the gearbox limits.  But I also know that people like Jake Raby have built very high output engines for customers where the gearbox's survived just fine, but I have no idea what if any mods he may have made to the trans to make this work.  Again, these cars are a system, changing one thing can result in needed alterations elsewhere like in the driveline.