[edub92]

Hey 2addicts,


My name is Eric. I have owned my 2014 M235i 6MT for a little over a year and I love this car. I currently use this car as my daily (and occassional auto-x/track toy) and I have a 2003 Honda S2000 that I use as my weekend car/track build.


Now my question is pretty simple so I'll ask it and then explain why I am asking the question...

Do you think an M235i can be track-prepped/built to reliably beat and compete with cars of the 991 GT3 caliber?


I am asking this question because:

• I want to know if my M235i will be my next track build (or should it be another car)
• I want to know if this car (chassis, etc) can comfortably handle 500-550HP
• I want to know if the N55 platform should be able to handle be able to handle 500-550HP while still being reliable... not looking for monster numbers
• IF the m235i can handle my requirements then i dont mind investing in some of the parts now that i plan to use for my track build later... (CAE shifter, MP exhaust and diffuser, etc)

To give you some more context a 991 GT3 is ~3100lbs, 500hp, 340lb-ft. I would like to tune the M235i to have power numbers that are slightly higher than those. I would also be stripping out most interior+unnecessary weight (dash, speakers, heater, AC, sound deadening etc) and adding a full roll cage. id also like to go w/ a fuel cell and dry sump and possibly the m235i widebody or even the manhart widebody kit in order to fit a meaty/square setup.


I know that there is the M235iR platform and that is why I am very hopeful that my M235i will be a solid choice for my next track build. It seems that the N55 engine in the M235iR can reliably run in 24hr endurance races at stock power! I just need to be able to run sessions that are <=1hr at ~1.5x stock power.

I have also seen that AC Schnitzer has their ACL2 w/ an S55 making 560hp and making amazing times... this gives me hope that the chassis should be more than cable of handling the numbers I am looking for?


my track prepped s2000 can outperform cars 3x its price point, my goal would be to make my track prepped m235i outperform cars 5-6x its price point. you could call this hypothetical car an m235i GTS!


Thanks for your time!

[capt_and]

Maybe... but doubtful. I don't think the engines will stand up to that power for very long. My build has been focused on suspension. My goal on my build is to get the car as fast as possible, without any real focus on what cars I need to beat. But, it'll cost more money than you think to get to that point, and then reliability becomes an issue. That's why I am not touching the engine or trans. If I can get the car to beat a GT3, great. But I want to do it with just suspension and aero.

Also, you are heading down the wrong path if that is ultimately your goal. You'll want a racing exhaust not the MP exhaust, the diffuser does almost absolutely nothing, and the shifter is pretty low on the list of things to do. The weak point of our cars out of the box is the suspension. I'd start there.

[Anthony235]

I've owned and tracked a S2000 as well.

As for your GT3 question....anything is possible if you throw enough time and money at it. How realistic is it for a modded m235i to compete against a stock 991 GT3 on a road course? Not very.

You would basically have to build a copy of the M235i Racing car and then add ~200hp reliably. Adding the power can be done relatively easy. The hard part is to make that power for 30+ minute track sessions. Chassis can handle 500hp in my opinion.

Rough estimate is ~$20k for parts. Then add any labor.

Honestly your s2k with ~$20k in parts will be a faster road course car then the modded m235i. Just model the s2k after the Evasive car. The BMW as a daily and the s2k as the track car is perfect in my opinion. Most fun car I've owned is the s2k.

I see you're in Socal. I only tracked the s2k at SOW, but I've done big willow in the m235. I think my s2k would be faster than the BMW at SOW.

1:23.xx in s2k at SOW (NT01 and Megan coils)
1:33.xx in BMW at Big Willow. (RE71 and KW Clubsports).

For comparison:
1:32.5 F80 M3 with Randy Pobst at Big Willow
1:24.6 991 GT3 with Randy Pobst at Big Willow

[dradernh]

Originally Posted by edub92

Do you think an M235i can be track-prepped/built to reliably beat and compete with cars of the 991 GT3 caliber?

I think of answers to questions like these in terms of cost. That is, without taking cost into account, yes, of course it can be done.

[edub92]

Originally Posted by capt_and

Maybe... but doubtful. I don't think the engines will stand up to that power for very long. My build has been focused on suspension. My goal on my build is to get the car as fast as possible, without any real focus on what cars I need to beat. But, it'll cost more money than you think to get to that point, and then reliability becomes an issue. That's why I am not touching the engine or trans. If I can get the car to beat a GT3, great. But I want to do it with just suspension and aero.

Also, you are heading down the wrong path if that is ultimately your goal. You'll want a racing exhaust not the MP exhaust, the diffuser does almost absolutely nothing, and the shifter is pretty low on the list of things to do. The weak point of our cars out of the box is the suspension. I'd start there.

capt_and I really like your build, glad i found your thread and instagram. i am one hundred percent with you as far as focusing on suspension and aero first and worrying about power later, that is exactly how i would start my build. i want to see how your experience with aero and suspension goes, i'm hoping that everything pans out well - this is exactly how i'm building my s2000 (evasive motorsports spec, like Anthony235 mentioned)

i read in your build thread that you purchased a miata to use as a learning tool... that's exactly why i purchased my s2000 a year ago. i originally had a lexus RC F but started tracking it and quickly realized that it was way too much car (and way too expensive) for a novice so i ended up trading it in and getting my current fleet. my s2000 is track learning tool/project car for the next 3 years and i hope that by then i have a great idea of how to drive and setup a car.

as far as my m235i is concerned i dont plan on modifying it beyond the basics for at least 3 years while i use it as my daily driver... 60 mile round trip commute to work in bumper to bumper traffic on the 405 freeway. the mods i listed would all be for me to enjoy the car for the next couple years - i would replace whatever parts necessary in order to hit my performance goals down the road.

ultimately it will come down to everything working together at a high capacity for me to hit the performance benchmark of a gt3. i know that i could probably go out and spend the money on a c7z06 and do no work but i would much rather spend the time building the car the way i want from the ground up!

[edub92]

Originally Posted by Anthony235

I've owned and tracked a S2000 as well.

As for your GT3 question....anything is possible if you throw enough time and money at it. How realistic is it for a modded m235i to compete against a stock 991 GT3 on a road course? Not very.

You would basically have to build a copy of the M235i Racing car and then add ~200hp reliably. Adding the power can be done relatively easy. The hard part is to make that power for 30+ minute track sessions. Chassis can handle 500hp in my opinion.

Rough estimate is ~$20k for parts. Then add any labor.

Honestly your s2k with ~$20k in parts will be a faster road course car then the modded m235i. Just model the s2k after the Evasive car. The BMW as a daily and the s2k as the track car is perfect in my opinion. Most fun car I've owned is the s2k.

I see you're in Socal. I only tracked the s2k at SOW, but I've done big willow in the m235. I think my s2k would be faster than the BMW at SOW.

1:23.xx in s2k at SOW (NT01 and Megan coils)
1:33.xx in BMW at Big Willow. (RE71 and KW Clubsports).

For comparison:
1:32.5 F80 M3 with Randy Pobst at Big Willow
1:24.6 991 GT3 with Randy Pobst at Big Willow

I'm 100% with you as far as most fun car, i bought my s2000 as a track toy/learning tool and ended up loving it more than any car ive ever owned. it actually turns out that im currently in the process of building it out just like the NA evasive car haha (http://superstreetonline.com/feature...4-honda-s2000/)... not touching the internals of the engine and using heavy aero, etc.

i think the s2000 is amazing for certain tracks (haven't done SOW yet but can't wait) but i also want to build a car that will have fun at high horsepower tracks. i recently took the s2000 and m235i to auto club speedway and while i had a blast in my s2000 it was nice to hit 140 in my m235i

i think 500 hp is reasonable to me for the m235i. i imagine w/ ~$25k i could probably get the car to a reliable 500hp, widebody kit (m235ir or manhart or whatever), wheels/tires, and a nice suspension setup. might need some more if the engine has to be fully built but i could do most of the basic stuff like upgrading the valve train and dry sump myself.

that being said... i dont know if that would be able to pull a 1:24.6 on big willow though... that's a pretty big gap to overcome.

i imagine with stripping the car down for weight, dialing in the suspension, and adding hoosiers you might be able to get the 2-3 seconds. adding weight back in for the cage and then adding aero and wider tires as well as more power... not sure how that would all add up.

yeah the 991 gt3 is a pretty tough goal lol.

[pikcachu]

https://www.2addicts.com/forums/show...php?p=22895677

[Maynard]

Personally, my elaborate fantasy trips tend to involve supermodels with remarkably poor judgment. But hey, if reliable 550hp motors and 240's beating cars worth "5-6x their price" works for you, have at it (that would be cars costing upwards of 200K, right? or did you mean 5-6x the worth of one that has been hacked?).

And while you are at it, I think it should also have that internet thing that lets you run it on plain tap water, so you can take all your gas money and spend it on a carbon fiber body that only weighs 20#.

[capt_and]

Originally Posted by edub92

i imagine w/ ~$25k i could probably get the car to a reliable 500hp, widebody kit (m235ir or manhart or whatever), wheels/tires, and a nice suspension setup. might need some more if the engine has to be fully built but i could do most of the basic stuff like upgrading the valve train and dry sump myself.



i imagine with stripping the car down for weight, dialing in the suspension, and adding hoosiers you might be able to get the 2-3 seconds. adding weight back in for the cage and then adding aero and wider tires as well as more power... not sure how that would all add up.

Well, now that I have an idea of your budget, I can affirmatively tell you no, getting to GT3 level won't happen. For a car this weight, you'll want to run 295-305 tires. To do that you'll need the widebody which will cost roughly $7k-8k for parts plus install. Let's say install is $3k. You're at $10k-$11k. Add paint or wrap which will be $2k - $3k. Now, you'll need spacers, studs, and 11" wheels. That's going to be another $2.5k going the budget route. Now the suspension will need mucho camber and have to be a motorsport suspension that won't over heat, can handle Hoosiers, and adjustable enough that you can fine tune it. Add $8k for the camber plates, coilovers, and springs - diy on the install. Add tires and that's $1.5k. Sway bars or the car will roll like a Miata - $650, diy install. You're already well over budget. You'll need another $8k for the roll cage, $2k for seats/harnesses (budget route), and $800 for a good motorsport exhaust. Plus bushings, control arms, linkages, etc. For the n55 motor, you'll want an intercooler and something to address the oil/fuel starvation issues.

Now, if you want to build a car that can beat an M2, that'll be $5k for camber, good coilovers, wheels, and tires. Also assuming you can properly dial in the car yourself. You can beat a lot of cars with just this stuff - I did... But of course, it all comes down to the driver. I'd spend the $5k for the basic suspension stuff, add seats/harness/roll bar, then spend some good money to get coaching. The money I've spent on coaching has improved my time more than anything else dollar for dollar. I've passed Huracan Performantes, GT3s, GT3RS, Corvettes, you name it. That's not because my car is faster, that's because my margin of skill over the other guy is greater than the capabilities of his car over mine.

Here's a video of my coach from the 90's in a Civic passing a Ferrari F40. And yes, they were racing each other - the F40 lost.

[Anthony235]

Originally Posted by edub92

I'm 100% with you as far as most fun car, i bought my s2000 as a track toy/learning tool and ended up loving it more than any car ive ever owned. it actually turns out that im currently in the process of building it out just like the NA evasive car haha (http://superstreetonline.com/feature...4-honda-s2000/)... not touching the internals of the engine and using heavy aero, etc.

i think the s2000 is amazing for certain tracks (haven't done SOW yet but can't wait) but i also want to build a car that will have fun at high horsepower tracks. i recently took the s2000 and m235i to auto club speedway and while i had a blast in my s2000 it was nice to hit 140 in my m235i

i think 500 hp is reasonable to me for the m235i. i imagine w/ ~$25k i could probably get the car to a reliable 500hp, widebody kit (m235ir or manhart or whatever), wheels/tires, and a nice suspension setup. might need some more if the engine has to be fully built but i could do most of the basic stuff like upgrading the valve train and dry sump myself.

that being said... i dont know if that would be able to pull a 1:24.6 on big willow though... that's a pretty big gap to overcome.

i imagine with stripping the car down for weight, dialing in the suspension, and adding hoosiers you might be able to get the 2-3 seconds. adding weight back in for the cage and then adding aero and wider tires as well as more power... not sure how that would all add up.

yeah the 991 gt3 is a pretty tough goal lol.

I bought a RX8 as a track learning tool to step into RWD. Then went s2k.

s2k can be competive in most bigger tracks like buttonwillow. Autoclub is definitively a high HP track that still requires a good setup. That's probably my favorite track. I did 1:55.xx there in my EvoX on RS3 tires. That was with some serious fuel starvation issues.

You could run the 500hp without opening up the engine. Just run it until/if it breaks. Then build it up. Some of the street cars have been running 500+hp for a few years without issue. I would go with the m235ir widebody over any of the others for sure. Track proven and I know it comes with the fender liners (small, but big detail) for aero.

I didn't finish setting up my coilovers when I did my run at big willow. With that setup and LSD I think I would have been deep into the 1:32.xx range. With basic aero maybe another 1-1.5 seconds.

I see a build like you're considering a ~1:26 car at Big willow. As long as the driver is up to spec.

[edub92]

Originally Posted by Maynard

Personally, my elaborate fantasy trips tend to involve supermodels with remarkably poor judgment. But hey, if reliable 550hp motors and 240's beating cars worth "5-6x their price" works for you, have at it (that would be cars costing upwards of 200K, right? or did you mean 5-6x the worth of one that has been hacked?).

And while you are at it, I think it should also have that internet thing that lets you run it on plain tap water, so you can take all your gas money and spend it on a carbon fiber body that only weighs 20#.

[dradernh]

Originally Posted by edub92

i imagine w/ ~$25k i could probably get the car to a reliable 500hp, widebody kit (m235ir or manhart or whatever), wheels/tires, and a nice suspension setup.

My experience leads me to suggest that you think in terms of $75K to start, with surprises and facts popping up along the way to take your spend into six figures.

Here's an idea that will cost you little to nothing: find the most competent race car shop that you'd be willing to drive to, make an appointment to go see them and tell them what you want, and ask them what they think it would cost for them to build it for you. Use a real race shop, one that builds race cars that don't break - i.e., don't use a tuner shop that just installs parts. I found mine by trolling a local SCCA race meeting looking for a shop that was supporting multiple cars that were doing well.

FWIW, it's the reliable part that makes the numbers what they are.

Originally Posted by capt_and

...spend some good money to get coaching. The money I've spent on coaching has improved my time more than anything else dollar for dollar.

^ This.

I've spent probably 20 days at tracks all over the Northeast with pro race drivers coaching me. That made me faster than all the go-fast parts on my car did. Putting it politely, the fact is that 95% of us track day guys don't drive very well. A pro will lock right in on what you need to change to go faster, and you'll do it safer than you were when you were going slow. Budget at least a few grand for that exercise, too - it will be the best money you've ever spent making yourself go faster.

To me, the bottom line issue is this: do you want your car to be fast, do you want to be fast, or do you want both to be fast? My advice is the same old thing: first, fix the nut behind the wheel.

Whatever you do, have fun with it!

[edub92]

Originally Posted by capt_and

Well, now that I have an idea of your budget, I can affirmatively tell you no, getting to GT3 level won't happen. For a car this weight, you'll want to run 295-305 tires. To do that you'll need the widebody which will cost roughly $7k-8k for parts plus install. Let's say install is $3k. You're at $10k-$11k. Add paint or wrap which will be $2k - $3k. Now, you'll need spacers, studs, and 11" wheels. That's going to be another $2.5k going the budget route. Now the suspension will need mucho camber and have to be a motorsport suspension that won't over heat, can handle Hoosiers, and adjustable enough that you can fine tune it. Add $8k for the camber plates, coilovers, and springs - diy on the install. Add tires and that's $1.5k. Sway bars or the car will roll like a Miata - $650, diy install. You're already well over budget. You'll need another $8k for the roll cage, $2k for seats/harnesses (budget route), and $800 for a good motorsport exhaust. Plus bushings, control arms, linkages, etc. For the n55 motor, you'll want an intercooler and something to address the oil/fuel starvation issues.

Now, if you want to build a car that can beat an M2, that'll be $5k for camber, good coilovers, wheels, and tires. Also assuming you can properly dial in the car yourself. You can beat a lot of cars with just this stuff - I did... But of course, it all comes down to the driver. I'd spend the $5k for the basic suspension stuff, add seats/harness/roll bar, then spend some good money to get coaching. The money I've spent on coaching has improved my time more than anything else dollar for dollar. I've passed Huracan Performantes, GT3s, GT3RS, Corvettes, you name it. That's not because my car is faster, that's because my margin of skill over the other guy is greater than the capabilities of his car over mine.

Here's a video of my coach from the 90's in a Civic passing a Ferrari F40. And yes, they were racing each other - the F40 lost.

Hmmm i'll have to re-evaluate my theoretical build, i wasn't budgeting nearly as high for the widebody parts+install (i was thinking widebody prices were in the 5k neighborhood, install for 2-3k) or for the full cage (was imagining a price in 4k neighborhood, not double that).

there is no hard cap dollar amount at this point for my theoretical build, im just trying to figure out if this is the route i actually want to go down. my "rule of thumb" at this point has been to not spend too much over purchase price improving the car... my s2000 was 15k and im budgeting the build to around 20k. i imagine the m235i will be worth around 25k (in a couple years, when i start on the build) so i would say my budget should be around 33k.

at the end of the day im not splitting hairs over an extra 5-10k as long as my build total stays at a "reasonable price" relative to the goal. if the car is 25k and im into the build for 35k for a total of 60k and im able to have the car perform at a similar capacity to a 991 gt3 then i would consider that a success in my book. i imagine that the 991 gt3 will still be worth somewhere between 120-150k at that point


from what ive read online (and from the respones ive gotten) it seems like pushing the car in the neighborhood of 500whp isn't insane. i know that the dinan m235i runs at around 450 (under full warranty) so using that as a benchmark, i dont think 500 is too far off. 550 reliably may be a stretch, unless the engine is built.

if the car can first be tuned to handle square 295 hoosiers (suspension and chassis willing) per the route youre going then i think power could be added afterwards and the car would be able to handle it. again all my research seems to point to this case. i dont need the car to run 24hr endurance races w/ square 295 and 500whp, i just want to run 30min sessions and compete in time attack!

to be honest i think that my goal is possible, it's just that my original stated budget of 25k may need a 30-50% increase. your numbers make me realize i was definitely dreaming a bit on pricing

[edub92]

Originally Posted by dradernh

My experience leads me to suggest that you think in terms of $75K to start, with surprises and facts popping up along the way to take your spend into six figures.

Here's an idea that will cost you little to nothing: find the most competent race car shop that you'd be willing to drive to, make an appointment to go see them and tell them what you want, and ask them what they think it would cost for them to build it for you. Use a real race shop, one that builds race cars that don't break - i.e., don't use a tuner shop that just installs parts. I found mine by trolling a local SCCA race meeting looking for a shop that was supporting multiple cars that were doing well.

FWIW, it's the reliable part that makes the numbers what they are.


^ This.

I've spent probably 20 days at tracks all over the Northeast with pro race drivers coaching me. That made me faster than all the go-fast parts on my car did. Putting it politely, the fact is that 95% of us track day guys don't drive very well. A pro will lock right in on what you need to change to go faster, and you'll do it safer than you were when you were going slow. Budget at least a few grand for that exercise, too - it will be the best money you've ever spent making yourself go faster.

To me, the bottom line issue is this: do you want your car to be fast, do you want to be fast, or do you want both to be fast? My advice is the same old thing: first, fix the nut behind the wheel.

Whatever you do, have fun with it!

I like this idea of consulting with local racing shops, I think I will try that out. again this build is meant to be in a couple of years, just trying to understand if this car is even a candidate for my next build.


Maybe im getting the wrong impression here (from other replys as well) but i want to reiterate that i do value the driver mod as the most important. i dont plan on experimenting with my m235i until im an amazing driver with my s2000. that is my miata/learning tool.

im currently averaging around 1.5-2 track days a month with my s2000, been trying to learn as much as possible. i also have a full fanatec simulator setup that i use to practice on an almost daily basis... yes, i know, i am obsessed. im a software engineer with too much money and time

i guess the point im trying to make is that im 100% with you and the other replies as far as seat time, instruction, and driver skill are concerned. i am investing a lot of my time and money into making sure that i am not the weak link in this equation!

[edub92]

Originally Posted by Anthony235

I bought a RX8 as a track learning tool to step into RWD. Then went s2k.

s2k can be competive in most bigger tracks like buttonwillow. Autoclub is definitively a high HP track that still requires a good setup. That's probably my favorite track. I did 1:55.xx there in my EvoX on RS3 tires. That was with some serious fuel starvation issues.

You could run the 500hp without opening up the engine. Just run it until/if it breaks. Then build it up. Some of the street cars have been running 500+hp for a few years without issue. I would go with the m235ir widebody over any of the others for sure. Track proven and I know it comes with the fender liners (small, but big detail) for aero.

I didn't finish setting up my coilovers when I did my run at big willow. With that setup and LSD I think I would have been deep into the 1:32.xx range. With basic aero maybe another 1-1.5 seconds.

I see a build like you're considering a ~1:26 car at Big willow. As long as the driver is up to spec.

Yeah i think youre right about the m235ir... the other widebody kits look cool but im sure none have nearly as much testing as the m235ir one does. it's just nuts how much it costs!

i think a ~1:26 would be pretty great at big willow. especially given the weight/size of the car

my favorite track right now is buttonwillow (havent been to laguna seca yet, making the trip this november) so im building my s2000 w/ that track in mind.

[capt_and]

Another thing to note, it's easier to do everything at once to save on labor. So when you're ready to do everything, you can take it to a local shop (or even ship it to Texas Track Works since they'll know exactly what needs to be done and can get it done with less labor) and drop it off for a couple of months. That's exactly what I am doing with mine, which is why I was extra motivated to get a cheap old Miata to practice with. I might sell it when I get my car back but I'll probably keep it since I just realized just how cheap they are to run.

[Anthony235]

edub92 Consider running Bimmer Challenge Time Attack series. B3 is the most competitive class and where a modded m235i street car would be. Same organization that does the S2k Challenge.

I did it once for the fun of it at big willow. The car and I won the class so the m235i can be competitive.

Also I would suggest sticking to one track until you get your times/skill to where you feel comfortable. I tracked streets of willow for a few years before moving onto various tracks. Leave your ego at the door and compare laptimes to similar cars as a measuring stick for yourself. Also always take track advice with a grain of salt unless you know the actual skill level of the driver and what actual laptimes they are putting down.

[Dylan86]

I think with a healthy weight loss plan, the M235iR widebody/wider wheel&track mods, ball joint 4-links, BBK, LSD (a must) and PS2 (of course all of the other suspension/chassis components not worth mentioning) could be very close to competitive with 991 GT3's, just don't make that the reason.. These cars are already higher performers than their price point would typically dictate, so you're ahead in a sense already, to start things off. You could, in theory, beat a 991 GT3 tomorrow at a track, simply due to poor or less skilled drivers driving them. But if trying to keep the pace with that class of "road/race car", I think it's possible, just really depends on the setup you go with and of course your comfort level to push the car to it's full potential at those stages of the build.

I feel I'll take my car to m235iR widebody, some 10"+ wheels and big tires, cage/race seats, PS2 (500whp range) stages in about 5 years or so. The car is ready, at this point, I am not, lol. The next project over the coming winter season is the M235iR oil pump/pick up mod, which is shared in the M2's N55, I think that would keep the car safe for almost any scenario, for oil starvation. That being said, I may take a different turn when that time comes, who knows what else is coming, or what other opportunities I'll come across. I've said it many times, there are not many cars I would consider to replace this car, with where my intentions are at. A Lotus Exige S has always been on my radar, and those (when modded up) can hang with all of the big boys, for sure. They are also appreciating in value, whereas the BMW is depreciating, and more so with modifications which you never get your money back on.. My experience so far with tracking this car, is that it's already very capable, and I need to spend more time in it before I decide if taking it to those final stages, will keep me content on my journey onward. It's a big "investment" int your hobby, at the end of the day..

As a baseline, though, what are the M235iR race cars lapping compared to 991 GT3's? I would imagine they're faster to a degree...

[dradernh]

Originally Posted by Dylan86

As a baseline, though, what are the M235iR race cars lapping compared to 991 GT3's? I would imagine they're faster to a degree...

Without running them back to back, it's tough comparing race cars to street cars. I mean, is the BMW on real race slicks while the GT3 is on street tires? Does the driver have the BMW strapped to his back, but he slides around on the OEM chair in the Porsche holding on to the wheel to stabilize himself?

My 2¢ is that if you put Pobst in both cars and on equal tires, he could drive the street GT3 to a faster time than the race M235iR. That's all I'd bet on it, too.

[Dylan86]

Originally Posted by dradernh

Without running them back to back, it's tough comparing race cars to street cars. I mean, is the BMW on real race slicks while the GT3 is on street tires? Does the driver have the BMW strapped to his back, but he slides around on the OEM chair in the Porsche holding on to the wheel to stabilize himself?

My 2¢ is that if you put Pobst in both cars and on equal tires, he could drive the street GT3 to a faster time than the race M235iR. That's all I'd bet on it, too.

Oh yea, of course, and tires are key. I do think the same, simply because the iR is down on power, big time. Put equal power/tires/driver in both said cars, and I would have to flip the favor to the iR

For the OP, he wants to lap faster than a 991 GT3 or in range, within range of them. I see 991 GT3's at the track as often as I see ZR1's/Grand Sports etc, which is not as common as you'd think. On a P-car event day, totally different story. What reality is, with the GT3, is that most drivers will never reach the limits of their cars, often enough on a track day to have a comparison made worthwhile.

Here's an example at Area27, in Oliver BC.

I ran a 2:23 flat on PSS's and stock suspension with Dinan lowering springs on my first ever attempt at this track last year. I was absolutely murdering the PSS's and the brakes weren't up for the braking points I'd like to be hitting. I feel I could gain about 5 seconds right off the hop with R compounds and better brakes. With more suspension work and a slight bump in power I feel I'd be in the low teens, here, for sure.

This 991 GT3 is owned by a fairly average skilled owner, for the P-Car world anyway.. He ran a 2:13:98 on Trofeo R'sand as you can see, not the smoothest driver out there, but he gets around pretty well. Obviously he's no Andretti, and he's got a lot of room to grow, but this is your "average guy" in his 991 GT3, on a weekend track day, and what I'm talking about in regard to what you'll see more often than not.

Insert a semi-professional driver in the exact same car and you break the production car record, at this track, with a 2:07:86!! I know it's an RS, but you can clearly see how smooth he is in comparison, late braking etc.

If we're talking about competition racing, different story there. If we're talking about being a total underdog on weekend track events, an m235 built right, with a solid driver, will hurt A LOT of feelings. Just my $.02

D