Impressions of my 981 Boxster w/ BGB 3.8L 991S conversion
07-29-2014, 02:22 PM
#76
Basic Sponsor
Rennlist
Site Sponsor
Rennlist
Site Sponsor
You have managed to answer your own question about as well as possible. That is a factor of the combination of two things: 1.) the Porsche boxer motor 2.) the dyno (car sitting still in a room that is over 100 degrees.) As you pointed out, that is the point where all motors begin to need air at a critical sweet spot and when it's hot and the air quality sucks, that is the big differential. It is for this reason that I think that whoever designed the Power Kit manifold and how it pneumatically changes runner sizes at 5K RPM helps this as much as it helps maintaining torque at low RPM levels and RPM at high levels when you want a different intake runner size. The Power Kit manifold IS HUGE for power.
Peak power across most all conditions on these motors seemed to be relatively the same wherever we went from race to race but when the air was good, the dip was not nearly as severe.
John
P.S. I don't believe in sticking fans on decklids or opening decklids on Porsches while on the dyno. We like to heat soak the crap out of it as much as possible and to reiterate what you stated, if the car was going down the road, the dip would be far less noticeable. Even the flat 6 Porsche Daytona Prototype 3.99L RSR motor does that on a motor dyno.
Peak power across most all conditions on these motors seemed to be relatively the same wherever we went from race to race but when the air was good, the dip was not nearly as severe.
John
P.S. I don't believe in sticking fans on decklids or opening decklids on Porsches while on the dyno. We like to heat soak the crap out of it as much as possible and to reiterate what you stated, if the car was going down the road, the dip would be far less noticeable. Even the flat 6 Porsche Daytona Prototype 3.99L RSR motor does that on a motor dyno.
09-15-2014, 01:57 PM
#77
4th Gear
Join Date: Dec 2012
Posts: 4
Likes: 0
Received 0 Likes
on
0 Posts
With my 3.8L now complete and 300 miles of road testing I must say this car is simply amazing! The added torque and hp is more than I expected. I wish to thank the 3.8L conversion group for their honest testimony regarding their builds and BGB for making this happen.
11-29-2014, 01:01 PM
#79
Basic Sponsor
Rennlist
Site Sponsor
Rennlist
Site Sponsor
Folks,
Used 2.7L 981 Caymans are selling for as low as $50K. We have openings in January for another build. Do we have any interested parties?
Thanks!
John
Used 2.7L 981 Caymans are selling for as low as $50K. We have openings in January for another build. Do we have any interested parties?
Thanks!
John
12-09-2014, 04:32 PM
#81
Do you have any straight line performance numbers for the car? Eg 0-60 and 1/4 mile times? I'd like to consider this for a Boxster. I have a 991 and like it, love the dynamics but really miss the power from my C6 Vette. The 991, 7 years newer and $40k more expensive just feels slow in comparison and I'm wondering if the Boxster 3.8 would bridge that gap.
12-10-2014, 07:15 PM
#83
Kudos to Lee88 and BGP, you made a dream car, ..or to my eyes, a perfect one.
For 30 years, I was non stop a 911's daily driver. Why I did choose to have 911's, simply because it was for me the best compromise sport/utility (2 back seats) car. For years I drove my children to school on the mornings, used the "back seats to put golf bags, going to Costco, etc..
Then about a year and half ago, I traded in my last 911 (a 2002 996 C4 Cab, that I had for 11 years) for a Panamera 4S. All good, no more "room problem", ..but then missing the stick shift and the button that "removes" the roof. So, I bought an old Boxster S, ..with PSS9 on each corner, ..and "discovered" that these Boxster are the best handling car I ever had !
And in addition to that, ..nobody "looks at you", ..which is something that I like very much.
So : tracks days, etc.. enjoying it big time, ..but, one thing is missing : "juice" !
I started to think that the Ruf 3800S should be the best Porsche of all, but now, reading what you did, ..just sound to me, being the Perfect thing to do.
I'm curious to know if BGP have done already 3.8 (or 4.0) implants on a 986 ? ..Or if such work (too old car, i.e.: all the wiring/can bus, electronics sensors outside the engine, i.e.: brakes, etc.. makes such kind of implant way to complex/expensive, to achieve ?
For 30 years, I was non stop a 911's daily driver. Why I did choose to have 911's, simply because it was for me the best compromise sport/utility (2 back seats) car. For years I drove my children to school on the mornings, used the "back seats to put golf bags, going to Costco, etc..
Then about a year and half ago, I traded in my last 911 (a 2002 996 C4 Cab, that I had for 11 years) for a Panamera 4S. All good, no more "room problem", ..but then missing the stick shift and the button that "removes" the roof. So, I bought an old Boxster S, ..with PSS9 on each corner, ..and "discovered" that these Boxster are the best handling car I ever had !
And in addition to that, ..nobody "looks at you", ..which is something that I like very much.
So : tracks days, etc.. enjoying it big time, ..but, one thing is missing : "juice" !
I started to think that the Ruf 3800S should be the best Porsche of all, but now, reading what you did, ..just sound to me, being the Perfect thing to do.
I'm curious to know if BGP have done already 3.8 (or 4.0) implants on a 986 ? ..Or if such work (too old car, i.e.: all the wiring/can bus, electronics sensors outside the engine, i.e.: brakes, etc.. makes such kind of implant way to complex/expensive, to achieve ?
Last edited by GVA-SFO; 12-10-2014 at 07:45 PM.
12-10-2014, 07:41 PM
#84
Do you have any straight line performance numbers for the car? Eg 0-60 and 1/4 mile times? I'd like to consider this for a Boxster. I have a 991 and like it, love the dynamics but really miss the power from my C6 Vette. The 991, 7 years newer and $40k more expensive just feels slow in comparison and I'm wondering if the Boxster 3.8 would bridge that gap.
It is true that I have seen (on track) recently, that on high speed, (if this is your zone of "fun") that GT3's can be much more efficient that any could measure (i.e.: on dyno, or on "specs") !
I mean that I think that above the 150mph range, the GT3's seems to get substantially more power and become real fast. I can only think that the air intake geometry gives such high air pressure, and having the ECU (and engine fuel pumps) tuned to give more gas when such speed is there, bringing serious extra power, ..that is NOT into any "books".
Or: if you are a "fast on straight line" person, ..may be a recent GT3 can give you such feel !
(..and btw, on pure 0 to 400 meters, a car with the engine "in the back" gives you the best "weight on rear wheels" when accelerating, ..or a "cheap way" to pass the power to the asphalt.)
Last edited by GVA-SFO; 12-10-2014 at 08:04 PM.
12-12-2014, 10:11 AM
#85
Basic Sponsor
Rennlist
Site Sponsor
Rennlist
Site Sponsor
Mike...you can't drop the thread subscription! I follow you everywhere!
Sorry for any delays as things are busy in the shop! Unfortunately I do not have any technical information about acceleration. The only thing I can tell you is that with all things being equal (991 vs. 981), the conversion cars do accelerate more quickly because they make the same HP/TQ on the dyno but weigh less because of the fact that they're Caymans. The new 991's 7-speed transmission that shares the PDK ratios bridges the gap much closer though on the transmission front. Among Caymans, if it's a 2.7L it has a "short ratio" box from the factory whereas the 3.4L has taller gearing. The base 2.7L cars have a shorter 1,2,3,5 and 6 vs. the 3.4L cars but both have the same shorter final drive ratio from the PDK of 3.89. Historically the 997 had a final drive ratio of 3.44.
So...without actual testing, the "butt" data supports that yes, they do accelerate more quickly than big brother and on the race track. I rode with a customer that had no issues running down a 991 3.8L S in a straight line at VIR. We reached 160mph at VIR on the back stretch in a street car with old R compound tires and no ECU flash or Limited Slip Differential!
You have done your homework and it's amazing how many people don't realize that having the engine over the tires is the best for acceleration. So many people discount the 911 setup as old, antiquated technology! It's 40-50 years of real race track development. Having said that, shops like BGB do not shy away from crazy builds like the one you suggested above. If it's older than a 2013, we have an ECU file for it. Everytrhing is always a question of wiring and parts but if parts can be found, we can make them work. While we have not done 3.8 or 4.0 conversions to a 986, we have done them to newer cars. I have a customer in Florida with a 997.2 chassis harness and 3.8L DFI Carrera S engine. he had started a project to put all of this in a 986 but he's now too busy and wanting to know if I know of someone interested. His name is Harry...he's a good guy and patrols these boards. Maybe it's worth our reaching out to him? I'm headed to Sebring to deliver another x51 PDK Cayman that we did some work to for an event. I am reachable all day via phone...or feel free to email me. Thanks for the kind words about the work we do! Cheers! P.S. The 911 has a sealed "RAM AIR" intake setup over the rear glass that shoves air right into the throttle body that sits no less than 10" from the decklid. As you approach 160mph and RAM AIR occurs, because it's sealed, the 911 GT3 is pulling like a freight train at 150 + MPH!
Do you have any straight line performance numbers for the car? Eg 0-60 and 1/4 mile times? I'd like to consider this for a Boxster. I have a 991 and like it, love the dynamics but really miss the power from my C6 Vette. The 991, 7 years newer and $40k more expensive just feels slow in comparison and I'm wondering if the Boxster 3.8 would bridge that gap.
So...without actual testing, the "butt" data supports that yes, they do accelerate more quickly than big brother and on the race track. I rode with a customer that had no issues running down a 991 3.8L S in a straight line at VIR. We reached 160mph at VIR on the back stretch in a street car with old R compound tires and no ECU flash or Limited Slip Differential!
Being an "old Porsche" guy, ..but having a lot of respects to Corvette's, I would tend to say that I doubt that 400hp on a Boxster chassis (weight) ..would be enough "to do" what you are looking for! I.e., I think you need to have a "P. Turbo" power to get there !
It is true that I have seen (on track) recently, that on high speed, (if this is your zone of "fun") that GT3's can be much more efficient that any could measure (i.e.: on dyno, or on "specs") !
I mean that I think that above the 150mph range, the GT3's seems to get substantially more power and become real fast. I can only think that the air intake geometry gives such high air pressure, and having the ECU (and engine fuel pumps) tuned to give more gas when such speed is there, bringing serious extra power, ..that is NOT into any "books".
Or: if you are a "fast on straight line" person, ..may be a recent GT3 can give you such feel !
(..and btw, on pure 0 to 400 meters, a car with the engine "in the back" gives you the best "weight on rear wheels" when accelerating, ..or a "cheap way" to pass the power to the asphalt.)
It is true that I have seen (on track) recently, that on high speed, (if this is your zone of "fun") that GT3's can be much more efficient that any could measure (i.e.: on dyno, or on "specs") !
I mean that I think that above the 150mph range, the GT3's seems to get substantially more power and become real fast. I can only think that the air intake geometry gives such high air pressure, and having the ECU (and engine fuel pumps) tuned to give more gas when such speed is there, bringing serious extra power, ..that is NOT into any "books".
Or: if you are a "fast on straight line" person, ..may be a recent GT3 can give you such feel !
(..and btw, on pure 0 to 400 meters, a car with the engine "in the back" gives you the best "weight on rear wheels" when accelerating, ..or a "cheap way" to pass the power to the asphalt.)
12-14-2014, 05:11 AM
#86
Yes, with the amount of miles I have accumulated driving many 911’s over 30 years, non stop as daily, I think, I understood a little bit the animal !
Yes, to pass the power from the tires to the asphalt, the 911 architecture is the best.
In my case, I was a loyal 911 customer for another reason : the two little seats on the back, ..or the fact that the 911 is (for my eyes) the “best compromise sport car”. (Now, having a Panamera, I do not care about “room and comfort”, as I’m fully served on these.)
But I think, another fact, that is part of the characteristics of the (911) architecture, is even less known : It is a VERY difficult car to drive, when you approach the limits.
What is easier to realize, is if you run with an heavy backsack, if you stop hard, we all know that then, the backsack will seriously tend to go over your head.
Very few realize that if you want to drive a 911 fast (i.e.: I mean track use), when you brake (hard), all the weight will dynamically go to the front.
So, all is good, but were it becomes very important, is to know that when you remove pressure (even a bit of it) on the brake pedal, ..the weight return to the back.
Very- very few do remember about that, i.e.: a 911 does good laps, ONLY if you brake at the EXACT braking point, as braking too early means having to release brake pressure before the turn and LOST of weight on the front axle, which is a must to trigger the turn in an efficient manner.
Frankly, braking at the EXACT braking point, is in my opinion, a VERY tough thing to do, when you are a “casual track driver”, ..which is my case.
For sure, I have seen many “pro drivers” that are able to manage to get the exact braking points of all the curves of a track, and this, in a very consistent manner. These are the only ones, that I consider being able to drive a 911 at the level of the (excellent) envelope of this car, ..but again, to my opinion, it does require a LOT of skills, talent, and also a lots of (track) miles.
Or, if we try to percent the number of GT2’s, GT3’s sold by the factory, over the number of skilled 911 drivers (the ones that always brake at the exact right point) , I would think, ..that the percentage is very-very-very low !
It is also clear that the electronic present, (and the 4WD) in all the new versions of this car have seriously reduced this effect (near the limit, having to call for the weight before triggering a turn) which is good, but, should I write here, that on the “early ones”, ..and thinking particularly to the early 930’s, I sadly lost friends on mountain roads over the years, ..that forgot this effect.
I have no idea in the USA, but, in Europe, sometime, the GT2’s carry a quite bad nickname : “the widow maker” !
Btw, we can observe that Porsche did acted about this effect, i.e.: having all the “regular” 911 Turbos being offered only with 4WD !
Well, all to go back on the very strong interest of the Boxster, that is a fabulous car, as it is MUCH more easier to drive when approaching the limits, thanks of the use of the best possible architecture for a sport car. (A car with athe engine in the center position is less sensitive to such effect.)
An old Boxster S, with PSS9 (coil over) is a FABULOUS sport car. Because of the above, any “regular driver” could quite easily stick to the back of any (non modified) 911S on track, ..thanks to the above explanations. Sure, on straight lines, you loose some field, ..but, it is relatively easy to be back on every curves !
..And after some given amount of track days, you get ONLY ONE envy : more juice !
So, I’m highly convinced, that what BGP is doing, is just the perfect thing to do.
Yes, to pass the power from the tires to the asphalt, the 911 architecture is the best.
In my case, I was a loyal 911 customer for another reason : the two little seats on the back, ..or the fact that the 911 is (for my eyes) the “best compromise sport car”. (Now, having a Panamera, I do not care about “room and comfort”, as I’m fully served on these.)
But I think, another fact, that is part of the characteristics of the (911) architecture, is even less known : It is a VERY difficult car to drive, when you approach the limits.
What is easier to realize, is if you run with an heavy backsack, if you stop hard, we all know that then, the backsack will seriously tend to go over your head.
Very few realize that if you want to drive a 911 fast (i.e.: I mean track use), when you brake (hard), all the weight will dynamically go to the front.
So, all is good, but were it becomes very important, is to know that when you remove pressure (even a bit of it) on the brake pedal, ..the weight return to the back.
Very- very few do remember about that, i.e.: a 911 does good laps, ONLY if you brake at the EXACT braking point, as braking too early means having to release brake pressure before the turn and LOST of weight on the front axle, which is a must to trigger the turn in an efficient manner.
Frankly, braking at the EXACT braking point, is in my opinion, a VERY tough thing to do, when you are a “casual track driver”, ..which is my case.
For sure, I have seen many “pro drivers” that are able to manage to get the exact braking points of all the curves of a track, and this, in a very consistent manner. These are the only ones, that I consider being able to drive a 911 at the level of the (excellent) envelope of this car, ..but again, to my opinion, it does require a LOT of skills, talent, and also a lots of (track) miles.
Or, if we try to percent the number of GT2’s, GT3’s sold by the factory, over the number of skilled 911 drivers (the ones that always brake at the exact right point) , I would think, ..that the percentage is very-very-very low !
It is also clear that the electronic present, (and the 4WD) in all the new versions of this car have seriously reduced this effect (near the limit, having to call for the weight before triggering a turn) which is good, but, should I write here, that on the “early ones”, ..and thinking particularly to the early 930’s, I sadly lost friends on mountain roads over the years, ..that forgot this effect.
I have no idea in the USA, but, in Europe, sometime, the GT2’s carry a quite bad nickname : “the widow maker” !
Btw, we can observe that Porsche did acted about this effect, i.e.: having all the “regular” 911 Turbos being offered only with 4WD !
Well, all to go back on the very strong interest of the Boxster, that is a fabulous car, as it is MUCH more easier to drive when approaching the limits, thanks of the use of the best possible architecture for a sport car. (A car with athe engine in the center position is less sensitive to such effect.)
An old Boxster S, with PSS9 (coil over) is a FABULOUS sport car. Because of the above, any “regular driver” could quite easily stick to the back of any (non modified) 911S on track, ..thanks to the above explanations. Sure, on straight lines, you loose some field, ..but, it is relatively easy to be back on every curves !
..And after some given amount of track days, you get ONLY ONE envy : more juice !
So, I’m highly convinced, that what BGP is doing, is just the perfect thing to do.
Last edited by GVA-SFO; 12-21-2014 at 01:10 PM.
01-06-2015, 05:49 PM
#87
Awesome, this would be an ideal setup.
Can you provide more details on the PDK tuning or upgrade you talked about? Does it have the aggressive firmware tune as the 991 gt3?
Can you provide more details on the PDK tuning or upgrade you talked about? Does it have the aggressive firmware tune as the 991 gt3?
01-06-2015, 08:34 PM
#88
Have you guys cracked the 991/981 ECU or is that a car with standalone engine management?
01-07-2015, 02:17 AM
#89
Rennlist Member
Congrats. Keep us updated.
