As I take a lot of info from this place I though I would share some info on my car & a recent engine (re)build that may be of interest.
The car is a late 996.1 factory aero-kit, non-sunroof C2, bought as a project to upgrade and use.
The aim was to sympathetically upgrade into a fast road / track car using a clubsport mentality keeping it looking as standard as possible, while improving reliability, drive to the circuit, drive home – Where possible all upgrades would come from within the Porsche food chain, GT3 / RS / Cup, using genuine Porsche parts.
Buying a 996.1 GT3 was an option, but due to its initial cost, appreciating nature and rarity it would have just sat in the garage next to the other cars that I rarely drive. – I wanted something that I could use and enjoy without worrying about mileage, stone chips, modifying from standard etc etc. – This was to be as much about the journey as the destination.
I have been running the car for circa 2 years with a standard engine, albeit with LTT, centre rad, FVD X51 sump and the upgrades listed below, should anyone require any details on anything ask, however for the time being I will focus on the recently rebuilt engine.
Oversizing the M96 is becoming more popular but there is not a huge amount of info out there.
996.1 3.4 going to a 3.7. – Proactive upgrade as oppose to a failure. – I wanted a little more performance, and once the maths were complete, this made most sense to me, given where the car was and what else I could have gotten into.
Expectations, management of..,
As touched upon there is not a lot of these in circulation and as such not a lot of information on what to expect from a data/figures perspective. – In fact there is very little dyno info out there for the M96 cars in general, there is lots of speculation and assumption, but not a lot of hard fact. – Some say expect 350bhp from a 3.7 with some breathing mods, I was skeptical on this.
996 3.4 was rated at 296 bhp when factory fresh, most generally state the 300 PS number, with 256 ft/lbs of torque. – Having done a fair amount of research and spoken to both Wayne Scholfield & Charlie at Surrey Rolling Road, neither have ever seen an M96 make the quoted number, ever.
Mezgers general do make their numbers, M96 are always below. – The question is, how far below, data on this is thin on the ground, and given the cars are also circa 20 years old, wear would also contribute to lower still numbers.
As I needed a datum, ever the optimist in my mind I decided that my car would have produced 296 bhp and that over 18 years it will have only lost 5%, so the fictional output number I started with for mine was a 281.2 bhp.
I then stumbled upon a thread by Y2K, I hope he does not mind me sharing, he had his 996.1 dynoed at Surrey Rolling Road and was good enough to post the plot, at peak his car made 272 bhp with 250 ft/lbs, draw from this what you will, but I feel with this info and the comments from those who have a host of experience on the topic, is generally where the cars are at, and not anywhere near the much mentioned 300 number.
With the above in mind, getting a 3.4 from, lets say 280, to 350, with a 300cc increase and a few bolt on breathing mods seem totally unrealistic to me, and as such helps to manage and realign expectations.
The rough spec of my build was as follows, a big thanks to Hartech whom work with me, allowing me to deviate from the norm and for fitting lots of additional parts and items including some that are normally reserved for their race engines.
3.7 Closed Deck, Nikasil Liners, new forged pistons etc.
Carrillo forged Rods
Threaded Core Plugs
Custom Additional Crank Shaft Bearing.
Latest Large Porsche IMS
Lightweight Flywheel & Sprung Clutch, balanced to Crank
RSS Underdrive Pulley
X51 Intake Manifolds
X51 Runners
X51 Additional Oil Scavenge Pump
X51 Exhaust Manifolds
3.6 Cats
FVD Motorsport Sump with X51 Baffle
Secondary Air Pump Removal
ECU Remap (Wayne Scholfield)
The above was on top of a whole host of other upgrades and stuff, chains, seals, pumps, fuel rails etc etc etc. – In reality there was not much that wasn't changed! But none are really performance rated.
Now the only other performance related issue that I will share feed back on are, the heads, plenum, throttle body, airbox and air filter.
The standard 3.4 heads are CFD designed and generally flow well, polishing and light porting of the these produces very very modest gains, regardless I had them done, rebuilt and skimmed. – I was told to get more from them you need to move into the realms of adding more material to the ports and then reshaping, other stuff was also mentioned but it escapes me.
I looked into X51 heads, however I believe these are, with the excepting of being skimmed, identical to the standard heads, the difference in performance comes from the cams and valve profiles, not much info out there on these, and as much as I would have liked X51 heads, the costs and availability were a bridge to far for me on this project.
Plenum, I fitted an IPD competition plenum with a 997 GT3 82mm throttle body, linked to the standard airbox, with a resonator delete and BMC panel filter. – If the internet is to be believed this is a solid setup and should produce gains, this is where it got interesting.
The car was dynod, the results were deemed to be sub-optimal, so various items listed above were systemically removed and replaced in various combinations and the car again dyno'd immediately after to compare the results and this is what was discovered..,
IPD Plenum with 997 GT3 throttle body, reduced engine output and left flatspots and holes everywhere in the curve, apparently down to the lose of exhaust scavenging effect.
Resonator delete airbox with BMC filter, produced less bhp & torque than a standard airbox with a standard filter. - The rational, in deleting the resonator the airflow is more turbulent, the MAF doesn't like this and winds things back, standard filter flows more than enough air.
The optimum solution for the most bhp & torque was, standard airbox with resonator, standard air filter, standard throttle body and a 997S plenum.
People may have an opinion on this, however its based on data, and as much as the larger shiny throttle body, IPD plenum etc look great and make the car sound better, on my engine they did not increase performance, they hindered it.
In the end after lots of tuning, where did I end up, the engine produced 325 bhp and 290 ft/lbs of torque. – When it breaks in I may see a little more.
So based on my fictional starting point of 281bhp, I gained 44 bhp.
Based on Y2K's numbers, which may be more realistic, I gained 53 bhp & 40 lbs/ft of torque.
Based against the factory numbers I gained 29 bhp & 34 Ibs/ft.
996.1 GT3 factory numbers are 360bhp & 272 ft/lbs – Again from the info available these numbers are accurate with most cars dynoing in the mid 350's.
With the circa 50bhp gain, if the car had been producing 300 as standard, it would indeed have been circa 350, but the reality is, it doesn't and if your considering a conventional oversize, don't expect it to.
Once the engine is run in I will take VBox data on circuit which I can overlay against data I already have from before the work, this to me provides real world improvement data, which is more relevant and important than bhp numbers. – As is the fact that the engine should now be more robust, not that I had any issues prior to the rebuild.
As many of you know, you can get a dyno to read whatever you want it to, we all want high engine BHP numbers and things can be fudged to suit demanding clients and massage ego's, I don't really care so wanted 'real' numbers which I am prepared to share.
Car weight is another where people are coy, I'm at 1285Kg, with no fuel or driver, with both, which are critical, based on half a tank its circa 1400Kg's. – I've removed around 140Kg's from what was a lightly spec'd car from factory.
For context PCGB Class 1 996 3.4 Race Cars have a minimum weight requirement of 1295Kg
As far as a performance summary goes, I have nothing firm at present based on the cars actual weight, and the actual weight of a standard 996.1 GT3 I would expect the Power to Weight ratio to be very similar. – Much like the bhp figures quoted by Porsche, the weight figures are generally a long way off, with most cars being significantly heavier than people think, again a fact confirmed to me by Chris at Gravity Centre.
Spec.
Cooling :
Porsche front centre radiator, with GT2 chimney and Cup bumper vent
Porsche low temp thermostat
A/C modified to run with a single condenser, significantly increasing airflow to one rad.
Fan override switch
Transmission :
6 Speed Manual Gearbox
997 GT3 GearShift
Lightweight Flywheel, dynamically balanced to the crankshaft.
Sachs Performance Sprung Clutch
Sachs Performance Pressure Plate
Sachs release bearing
Motul Gearoil
Powerflex Gearbox Mount, revised design.
Front Axle :
JRZ Series 12 Cup Motorsport Coilover Dampers
Porsche GT3 cup Monoball top mounts
Porsche GT3 Cup 2 piece lower control arms
Porsche GT3 Cup adjustable anti-roll bar
Monoball adjustable drop links
New Porsche TRW steering rack, including tie-rods and track arms
Conversion to Porsche 997 Cup electric power steering pump.
Rear Axle :
JRZ Series 12 Cup Motorsport Coilover Dampers
Porsche GT3 Cup Monoball top mounts
Porsche GT3 Cup 2 piece Monoball lower control arms
Porsche Cup Adjustable Rear Toe Links
RSS Locking Toe Bolts
Porsche GT3 Cup adjustable anti-roll bar with Powerflex Bushes
Monoball adjustable drop links
Alignment & Setup completed by Gravity Center.
Brakes :
Front :
Porsche std calipers, wear sensor & anti-vibration shim delete.
Giro Disc Two Piece Floating 340mm Discs
Pagid RSL29 Pads
Motul RBF660 High Temp Brake Fluid
HEL Performance Stainless brake lines
Porsche 997 GT3 Front Lower Ducts
Porsche GT3 Cup Front upper brake ducts (Radiator cowls and wheel arch liners modified for airflow)
Custom 2" Brake Duct from from front Bumper to inside centre of front disc.
996 GT3/Turbo 25.4mm Master Cylinder
Rear :
Porsche std calipers, wear sensor & anti-vibration shim delete.
Giro Disc Two Piece Floating 330mm Discs
Pagid RSL29 Pads
Motul RBF660 High Temp Brake Fluid
HEL Performance Stainless brake lines
Porsche 997 GT3 Rear Ducts
Wheels & Tyres :
Porsche std 8" & 10" GT3 Wheels
Rennline Race Wheel Studs
235 x 285
H&R 7mm Front Spacer
H&R 12mm Rear Spacer
Wheel Edit;
Porsche Cup BBS E29 Split rims
9" Front - 245/35/18
10.5" Rear - 295/30/18
Exterior :
Porsche Factory Fitted Aero Kit
Non Sunroof Car (Not removed, not specified from factory)
Porsche Cup Car Front Splitter
ClubAutoSport Lightweight bonnet
Porsche Lightweight bonnet crest
Porsche Cup Car Rear Lexan Screen
Rear Wiper Delete (Done Properly via Bodyshop and not a plug)
Front Bumper meshed
Wheel arch modification to redirect radiator airpath.
Porsche Litronic Headlights with wash delete and Amberectomy
Interior :
Lightend Interior, using a ClubSport mentality. (Removed circa 105 Kg's) Edit: Now closer to 145Kg's
Porsche Handheld Fire Extinguisher
Porsche GT3 Centre Console Delete
Lightweight Carpets
Body Colour Centre Console
Rear Seat Delete
Porsche Cup Momo Steering Wheel
Heigo Clubsport Rear Roll Cage
Schroth Porsche 997 GT3 Harnesses (Floor mounted Crutch Strap)
GT3 Replica Carbon Bucket Seats, mounted via Porsche seat rails
Rennline Billet Gas Pedal Hinge
Engine :
Hartech 3.7 Closed Deck Build – Complete engine rebuild, virtually everything renewed or replaced (7 month build time)
Hartech Capricorn Forged Pistons
Hartech Capricon Nikasil Liners
Carrillo Forged Rods
Hartech Threaded core plugs
Hartech Additional crankshaft bearing (First Road Car)
Cylinder heads rebuilt, polished & skimmed
Latest 2006> Porsche large IMS Bearing
Porsche X51 Intake Manifolds
Porsche X51 Runners
Porsche X51 Exhaust Manifolds with Titanium Studs
Porsche X51 Additional Oil Scavenge Pump
Porsche X51 heatshields & a/c pipe work.
Porsche 997 3.8S Plenum
Porsche 3.6 Standard Cats
Lightweight TG Stainless Steel Sports Rear Boxes (Mild sounding to pass trackday db levels)
Secondary Air Pump Delete
Wayne Scholfield ECU Re-map
FVD Motorsport Sump, with X51 Baffle
Uprated Oil Pump components, Shaft (LNE), Piston & Spring (Porsche)
New Porsche Fuel rails, coolant tank, oil cooler, Water Pump, aos, Over engine brake lines, Clutch cylinder, Exhaust Hanger Brackets, all exhaust bolts are titanium for serviceability.
Porsche RS Engine Mounts
RSS 4" Underdrive Pulley
Belt driven Power Steering Pump removed.
PS-30 Powerlite LiFePo4 Lithium Ion Battery
There is probably more and the journey will continue, however this is all I can remember for now - Peace :bandit:
The car is a late 996.1 factory aero-kit, non-sunroof C2, bought as a project to upgrade and use.
The aim was to sympathetically upgrade into a fast road / track car using a clubsport mentality keeping it looking as standard as possible, while improving reliability, drive to the circuit, drive home – Where possible all upgrades would come from within the Porsche food chain, GT3 / RS / Cup, using genuine Porsche parts.
Buying a 996.1 GT3 was an option, but due to its initial cost, appreciating nature and rarity it would have just sat in the garage next to the other cars that I rarely drive. – I wanted something that I could use and enjoy without worrying about mileage, stone chips, modifying from standard etc etc. – This was to be as much about the journey as the destination.
I have been running the car for circa 2 years with a standard engine, albeit with LTT, centre rad, FVD X51 sump and the upgrades listed below, should anyone require any details on anything ask, however for the time being I will focus on the recently rebuilt engine.
Oversizing the M96 is becoming more popular but there is not a huge amount of info out there.
996.1 3.4 going to a 3.7. – Proactive upgrade as oppose to a failure. – I wanted a little more performance, and once the maths were complete, this made most sense to me, given where the car was and what else I could have gotten into.
Expectations, management of..,
As touched upon there is not a lot of these in circulation and as such not a lot of information on what to expect from a data/figures perspective. – In fact there is very little dyno info out there for the M96 cars in general, there is lots of speculation and assumption, but not a lot of hard fact. – Some say expect 350bhp from a 3.7 with some breathing mods, I was skeptical on this.
996 3.4 was rated at 296 bhp when factory fresh, most generally state the 300 PS number, with 256 ft/lbs of torque. – Having done a fair amount of research and spoken to both Wayne Scholfield & Charlie at Surrey Rolling Road, neither have ever seen an M96 make the quoted number, ever.
Mezgers general do make their numbers, M96 are always below. – The question is, how far below, data on this is thin on the ground, and given the cars are also circa 20 years old, wear would also contribute to lower still numbers.
As I needed a datum, ever the optimist in my mind I decided that my car would have produced 296 bhp and that over 18 years it will have only lost 5%, so the fictional output number I started with for mine was a 281.2 bhp.
I then stumbled upon a thread by Y2K, I hope he does not mind me sharing, he had his 996.1 dynoed at Surrey Rolling Road and was good enough to post the plot, at peak his car made 272 bhp with 250 ft/lbs, draw from this what you will, but I feel with this info and the comments from those who have a host of experience on the topic, is generally where the cars are at, and not anywhere near the much mentioned 300 number.
With the above in mind, getting a 3.4 from, lets say 280, to 350, with a 300cc increase and a few bolt on breathing mods seem totally unrealistic to me, and as such helps to manage and realign expectations.
The rough spec of my build was as follows, a big thanks to Hartech whom work with me, allowing me to deviate from the norm and for fitting lots of additional parts and items including some that are normally reserved for their race engines.
3.7 Closed Deck, Nikasil Liners, new forged pistons etc.
Carrillo forged Rods
Threaded Core Plugs
Custom Additional Crank Shaft Bearing.
Latest Large Porsche IMS
Lightweight Flywheel & Sprung Clutch, balanced to Crank
RSS Underdrive Pulley
X51 Intake Manifolds
X51 Runners
X51 Additional Oil Scavenge Pump
X51 Exhaust Manifolds
3.6 Cats
FVD Motorsport Sump with X51 Baffle
Secondary Air Pump Removal
ECU Remap (Wayne Scholfield)
The above was on top of a whole host of other upgrades and stuff, chains, seals, pumps, fuel rails etc etc etc. – In reality there was not much that wasn't changed! But none are really performance rated.
Now the only other performance related issue that I will share feed back on are, the heads, plenum, throttle body, airbox and air filter.
The standard 3.4 heads are CFD designed and generally flow well, polishing and light porting of the these produces very very modest gains, regardless I had them done, rebuilt and skimmed. – I was told to get more from them you need to move into the realms of adding more material to the ports and then reshaping, other stuff was also mentioned but it escapes me.
I looked into X51 heads, however I believe these are, with the excepting of being skimmed, identical to the standard heads, the difference in performance comes from the cams and valve profiles, not much info out there on these, and as much as I would have liked X51 heads, the costs and availability were a bridge to far for me on this project.
Plenum, I fitted an IPD competition plenum with a 997 GT3 82mm throttle body, linked to the standard airbox, with a resonator delete and BMC panel filter. – If the internet is to be believed this is a solid setup and should produce gains, this is where it got interesting.
The car was dynod, the results were deemed to be sub-optimal, so various items listed above were systemically removed and replaced in various combinations and the car again dyno'd immediately after to compare the results and this is what was discovered..,
IPD Plenum with 997 GT3 throttle body, reduced engine output and left flatspots and holes everywhere in the curve, apparently down to the lose of exhaust scavenging effect.
Resonator delete airbox with BMC filter, produced less bhp & torque than a standard airbox with a standard filter. - The rational, in deleting the resonator the airflow is more turbulent, the MAF doesn't like this and winds things back, standard filter flows more than enough air.
The optimum solution for the most bhp & torque was, standard airbox with resonator, standard air filter, standard throttle body and a 997S plenum.
People may have an opinion on this, however its based on data, and as much as the larger shiny throttle body, IPD plenum etc look great and make the car sound better, on my engine they did not increase performance, they hindered it.
In the end after lots of tuning, where did I end up, the engine produced 325 bhp and 290 ft/lbs of torque. – When it breaks in I may see a little more.
So based on my fictional starting point of 281bhp, I gained 44 bhp.
Based on Y2K's numbers, which may be more realistic, I gained 53 bhp & 40 lbs/ft of torque.
Based against the factory numbers I gained 29 bhp & 34 Ibs/ft.
996.1 GT3 factory numbers are 360bhp & 272 ft/lbs – Again from the info available these numbers are accurate with most cars dynoing in the mid 350's.
With the circa 50bhp gain, if the car had been producing 300 as standard, it would indeed have been circa 350, but the reality is, it doesn't and if your considering a conventional oversize, don't expect it to.
Once the engine is run in I will take VBox data on circuit which I can overlay against data I already have from before the work, this to me provides real world improvement data, which is more relevant and important than bhp numbers. – As is the fact that the engine should now be more robust, not that I had any issues prior to the rebuild.
As many of you know, you can get a dyno to read whatever you want it to, we all want high engine BHP numbers and things can be fudged to suit demanding clients and massage ego's, I don't really care so wanted 'real' numbers which I am prepared to share.
Car weight is another where people are coy, I'm at 1285Kg, with no fuel or driver, with both, which are critical, based on half a tank its circa 1400Kg's. – I've removed around 140Kg's from what was a lightly spec'd car from factory.
For context PCGB Class 1 996 3.4 Race Cars have a minimum weight requirement of 1295Kg
As far as a performance summary goes, I have nothing firm at present based on the cars actual weight, and the actual weight of a standard 996.1 GT3 I would expect the Power to Weight ratio to be very similar. – Much like the bhp figures quoted by Porsche, the weight figures are generally a long way off, with most cars being significantly heavier than people think, again a fact confirmed to me by Chris at Gravity Centre.
Spec.
Cooling :
Porsche front centre radiator, with GT2 chimney and Cup bumper vent
Porsche low temp thermostat
A/C modified to run with a single condenser, significantly increasing airflow to one rad.
Fan override switch
Transmission :
6 Speed Manual Gearbox
997 GT3 GearShift
Lightweight Flywheel, dynamically balanced to the crankshaft.
Sachs Performance Sprung Clutch
Sachs Performance Pressure Plate
Sachs release bearing
Motul Gearoil
Powerflex Gearbox Mount, revised design.
Front Axle :
JRZ Series 12 Cup Motorsport Coilover Dampers
Porsche GT3 cup Monoball top mounts
Porsche GT3 Cup 2 piece lower control arms
Porsche GT3 Cup adjustable anti-roll bar
Monoball adjustable drop links
New Porsche TRW steering rack, including tie-rods and track arms
Conversion to Porsche 997 Cup electric power steering pump.
Rear Axle :
JRZ Series 12 Cup Motorsport Coilover Dampers
Porsche GT3 Cup Monoball top mounts
Porsche GT3 Cup 2 piece Monoball lower control arms
Porsche Cup Adjustable Rear Toe Links
RSS Locking Toe Bolts
Porsche GT3 Cup adjustable anti-roll bar with Powerflex Bushes
Monoball adjustable drop links
Alignment & Setup completed by Gravity Center.
Brakes :
Front :
Porsche std calipers, wear sensor & anti-vibration shim delete.
Giro Disc Two Piece Floating 340mm Discs
Pagid RSL29 Pads
Motul RBF660 High Temp Brake Fluid
HEL Performance Stainless brake lines
Porsche 997 GT3 Front Lower Ducts
Porsche GT3 Cup Front upper brake ducts (Radiator cowls and wheel arch liners modified for airflow)
Custom 2" Brake Duct from from front Bumper to inside centre of front disc.
996 GT3/Turbo 25.4mm Master Cylinder
Rear :
Porsche std calipers, wear sensor & anti-vibration shim delete.
Giro Disc Two Piece Floating 330mm Discs
Pagid RSL29 Pads
Motul RBF660 High Temp Brake Fluid
HEL Performance Stainless brake lines
Porsche 997 GT3 Rear Ducts
Wheels & Tyres :
Porsche std 8" & 10" GT3 Wheels
Rennline Race Wheel Studs
235 x 285
H&R 7mm Front Spacer
H&R 12mm Rear Spacer
Wheel Edit;
Porsche Cup BBS E29 Split rims
9" Front - 245/35/18
10.5" Rear - 295/30/18
Exterior :
Porsche Factory Fitted Aero Kit
Non Sunroof Car (Not removed, not specified from factory)
Porsche Cup Car Front Splitter
ClubAutoSport Lightweight bonnet
Porsche Lightweight bonnet crest
Porsche Cup Car Rear Lexan Screen
Rear Wiper Delete (Done Properly via Bodyshop and not a plug)
Front Bumper meshed
Wheel arch modification to redirect radiator airpath.
Porsche Litronic Headlights with wash delete and Amberectomy
Interior :
Lightend Interior, using a ClubSport mentality. (Removed circa 105 Kg's) Edit: Now closer to 145Kg's
Porsche Handheld Fire Extinguisher
Porsche GT3 Centre Console Delete
Lightweight Carpets
Body Colour Centre Console
Rear Seat Delete
Porsche Cup Momo Steering Wheel
Heigo Clubsport Rear Roll Cage
Schroth Porsche 997 GT3 Harnesses (Floor mounted Crutch Strap)
GT3 Replica Carbon Bucket Seats, mounted via Porsche seat rails
Rennline Billet Gas Pedal Hinge
Engine :
Hartech 3.7 Closed Deck Build – Complete engine rebuild, virtually everything renewed or replaced (7 month build time)
Hartech Capricorn Forged Pistons
Hartech Capricon Nikasil Liners
Carrillo Forged Rods
Hartech Threaded core plugs
Hartech Additional crankshaft bearing (First Road Car)
Cylinder heads rebuilt, polished & skimmed
Latest 2006> Porsche large IMS Bearing
Porsche X51 Intake Manifolds
Porsche X51 Runners
Porsche X51 Exhaust Manifolds with Titanium Studs
Porsche X51 Additional Oil Scavenge Pump
Porsche X51 heatshields & a/c pipe work.
Porsche 997 3.8S Plenum
Porsche 3.6 Standard Cats
Lightweight TG Stainless Steel Sports Rear Boxes (Mild sounding to pass trackday db levels)
Secondary Air Pump Delete
Wayne Scholfield ECU Re-map
FVD Motorsport Sump, with X51 Baffle
Uprated Oil Pump components, Shaft (LNE), Piston & Spring (Porsche)
New Porsche Fuel rails, coolant tank, oil cooler, Water Pump, aos, Over engine brake lines, Clutch cylinder, Exhaust Hanger Brackets, all exhaust bolts are titanium for serviceability.
Porsche RS Engine Mounts
RSS 4" Underdrive Pulley
Belt driven Power Steering Pump removed.
PS-30 Powerlite LiFePo4 Lithium Ion Battery
There is probably more and the journey will continue, however this is all I can remember for now - Peace :bandit: