What did you do to your 996TT today?
11-06-2019, 07:12 PM
#5041
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Oh? What is being discussed on AM headers...?
11-06-2019, 09:35 PM
#5042
Really? I have not seen that debate, but the theory seems sound - less restriction, easier for the engine to pump, lower intake temps - this is the first I have heard of this. As I said, I was really just after the throttle body, the plenum just seemed like a plus part...
Will investigate further. Wouldn't mind hearing John's thoughts on it too.
Will investigate further. Wouldn't mind hearing John's thoughts on it too.
I will say that on my 4.0L we are using high flow 4" Marston Aerospace intercoolers, large 3" turbo intake pipes, a high flow intake manifold along with ported heads and intake runners. For numerous reasons, we are also using the OEM Y-pipe and OEM T-plenum along with the OEM 68mm throttle body. We have extensive datalogging capability and have the ability to log both pre-throttle and more importantly post-throttle manifold absolute pressure which allows us to see any potential bottle necks in that area. The engine at 1.25bar on 91octane fuel makes 727whp along with 699 wtq as you can see in the attached dyno. It's easy to make this type of power at 1.7+ bar but not so much so at the modest 1.2 and this speaks volumes to the overall efficiency of the air pump (engine). We have done over 20 different dyno pulls during the course of tuning with more to go to get it all perfect. Any change made to the engine hardware or software we verify on a real dyno, not a butt dyno. By all accounts, at our power level we do not see the OEM plenum/TB as a restriction in the very least especially in light of the 70whp increase between 6500 to 7500. A typical 500-520hp engine will have a 30% lower air flow demand placed on the intake system than our set up. You can draw your conclusion here.
The last thing I will add that people can think about when deciding between the 68 and 74mm TB in conjunction with the OEM Y-pipe. The internal diameter of the OEM Y-pipe just prior to the TB rubber coupler is less than the 68mm TB internal diameter. I measured it a while back and if I recall correctly, and don't quote me, it was 63mm, give or take. With that said, people can again draw their own conclusions of where the actual restriction is actually located and what flow benefit a larger TB can physically provide.
In closing, I can in no way discern even a 30-40whp delta in my set up and I'm very much in tune with my car. The only way we can get reliable data is by using a legit dyno in a controlled environment. Even using a dyno, there is a variance in output from run to run on the order of 10-15hp from things as simple a slightly higher IATs or a few extra degrees of heat soak. For reasons of repeatability, we try to do each pull at the same, or as close to the same, IAT and OAT as possible. Unless you are Lewis Hamilton, I simply do not buy into the fact that the average Joe can discern 15-30hp from simple mods on a 500-550hp engine via their "butt dyno". Anyone that claims so is a very gifted individual indeed or experiencing a confirmation bias to validate their purchase..
In light of the above, I would love to see a before and after pull on the same dyno with the same controlled conditions. Same dyno, same OAT, same IAT, same heat soak, etc, etc. Without controlled conditions however, it's meaningless. In over 10 years, I have yet to see a truly legit one. Hence my original post asking you to dyno pre/post install. Hope this makes sense. Cheers...
P.S. Oh yeah, I'm using OEM ported headers.
Last edited by powdrhound; 11-07-2019 at 12:37 AM.
11-06-2019, 09:56 PM
#5043
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Porsche's expertise has alway been flow. Getting more power out of an engine's displacement than the other manufacturers.
11-07-2019, 01:10 AM
#5044
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I'm going to refrain from commenting much here and turning this into a shiat storm as many guys are running these plenums and many vendors sell them. They may very well be a fantastic item.
I will say that on my 4.0L we are using high flow 4" Marston Aerospace intercoolers, large 3" turbo intake pipes, a high flow intake manifold along with ported heads and intake runners. For numerous reasons, we are also using the OEM Y-pipe and OEM T-plenum along with the OEM 68mm throttle body. We have extensive datalogging capability and have the ability to log both pre-throttle and more importantly post-throttle manifold absolute pressure which allows us to see any potential bottle necks in that area. The engine at 1.25bar on 91octane fuel makes 727whp along with 699 wtq as you can see in the attached dyno. It's easy to make this type of power at 1.7+ bar but not so much so at the modest 1.2 and this speaks volumes to the overall efficiency of the air pump (engine). We have done over 20 different dyno pulls during the course of tuning with more to go to get it all perfect. Any change made to the engine hardware or software we verify on a real dyno, not a butt dyno. By all accounts, at our power level we do not see the OEM plenum/TB as a restriction in the very least especially in light of the 70whp increase between 6500 to 7500. A typical 500-520hp engine will have a 30% lower air flow demand placed on the intake system than our set up. You can draw your conclusion here.
The last thing I will add that people can think about when deciding between the 68 and 74mm TB in conjunction with the OEM Y-pipe. The internal diameter of the OEM Y-pipe just prior to the TB rubber coupler is less than the 68mm TB internal diameter. I measured it a while back and if I recall correctly, and don't quote me, it was 63mm, give or take. With that said, people can again draw their own conclusions of where the actual restriction is actually located and what flow benefit a larger TB can physically provide.
In closing, I can in no way discern even a 30-40whp delta in my set up and I'm very much in tune with my car. The only way we can get reliable data is by using a legit dyno in a controlled environment. Even using a dyno, there is a variance in output from run to run on the order of 10-15hp from things as simple a slightly higher IATs or a few extra degrees of heat soak. For reasons of repeatability, we try to do each pull at the same, or as close to the same, IAT and OAT as possible. Unless you are Lewis Hamilton, I simply do not buy into the fact that the average Joe can discern 15-30hp from simple mods on a 500-550hp engine via their "butt dyno". Anyone that claims so is a very gifted individual indeed or experiencing a confirmation bias to validate their purchase..
In light of the above, I would love to see a before and after pull on the same dyno with the same controlled conditions. Same dyno, same OAT, same IAT, same heat soak, etc, etc. Without controlled conditions however, it's meaningless. In over 10 years, I have yet to see a truly legit one. Hence my original post asking you to dyno pre/post install. Hope this makes sense. Cheers...
P.S. Oh yeah, I'm using OEM ported headers.
I will say that on my 4.0L we are using high flow 4" Marston Aerospace intercoolers, large 3" turbo intake pipes, a high flow intake manifold along with ported heads and intake runners. For numerous reasons, we are also using the OEM Y-pipe and OEM T-plenum along with the OEM 68mm throttle body. We have extensive datalogging capability and have the ability to log both pre-throttle and more importantly post-throttle manifold absolute pressure which allows us to see any potential bottle necks in that area. The engine at 1.25bar on 91octane fuel makes 727whp along with 699 wtq as you can see in the attached dyno. It's easy to make this type of power at 1.7+ bar but not so much so at the modest 1.2 and this speaks volumes to the overall efficiency of the air pump (engine). We have done over 20 different dyno pulls during the course of tuning with more to go to get it all perfect. Any change made to the engine hardware or software we verify on a real dyno, not a butt dyno. By all accounts, at our power level we do not see the OEM plenum/TB as a restriction in the very least especially in light of the 70whp increase between 6500 to 7500. A typical 500-520hp engine will have a 30% lower air flow demand placed on the intake system than our set up. You can draw your conclusion here.
The last thing I will add that people can think about when deciding between the 68 and 74mm TB in conjunction with the OEM Y-pipe. The internal diameter of the OEM Y-pipe just prior to the TB rubber coupler is less than the 68mm TB internal diameter. I measured it a while back and if I recall correctly, and don't quote me, it was 63mm, give or take. With that said, people can again draw their own conclusions of where the actual restriction is actually located and what flow benefit a larger TB can physically provide.
In closing, I can in no way discern even a 30-40whp delta in my set up and I'm very much in tune with my car. The only way we can get reliable data is by using a legit dyno in a controlled environment. Even using a dyno, there is a variance in output from run to run on the order of 10-15hp from things as simple a slightly higher IATs or a few extra degrees of heat soak. For reasons of repeatability, we try to do each pull at the same, or as close to the same, IAT and OAT as possible. Unless you are Lewis Hamilton, I simply do not buy into the fact that the average Joe can discern 15-30hp from simple mods on a 500-550hp engine via their "butt dyno". Anyone that claims so is a very gifted individual indeed or experiencing a confirmation bias to validate their purchase..
In light of the above, I would love to see a before and after pull on the same dyno with the same controlled conditions. Same dyno, same OAT, same IAT, same heat soak, etc, etc. Without controlled conditions however, it's meaningless. In over 10 years, I have yet to see a truly legit one. Hence my original post asking you to dyno pre/post install. Hope this makes sense. Cheers...
P.S. Oh yeah, I'm using OEM ported headers.
I agree with you in that my butt dyno is probably not in that great 'alignment' with realistic power numbers, but would you have seen better flow, lower IAT numbers with a 1/4" bigger TB? I was not aware of the ongoing debate and my issue is around my gummed up TB, no doubt due to the fact that it ia a) 15 years old, and b) previous owner was not at all hard on the car - I mean, when I took the car, there was oil separation build up at the top of the filler tube, so it was rarely, if ever, run hard an put away wet.
In a past build, I took a B18C5R Honda engine apart and rebuilt it with all the super sexy Japanese parts I could find, ported the heads, lightened the flywheel, put 9200rpm cams and supporting hardware in it and went to the dyno. Imagine my disappointment, when after all this work, the car only put down 210whp. I was floored (and pretty pissed) until I started looking at restriction in the intake system. I had machined my own velocity stack and fabricated my own intake snorkel, but then I started looking at the TB, which was only 62mm, no fitted to an engine that cut the fuel at 9500rpm.
I fitted a 70mm TB and bam! 230whp, 265/70ish at the crank, with a dead flat AFR without it getting rich from 6500rpm +. It was my first real lessen in flow - it didn't matter that my heads were now flowing 250cfm at .5/' lift if I couldn't feed them.
My thinking was that not only would I address the problem with the gummed up TB, by removing about a 1/4" restriction, at the TB, I would be able to flow extra air, lean it out a bit and address the rich condition - of course, I may in fact be wrong in the Porsche world, but it sure made the world of difference in the Honda world.
Now, I want to dyno it.
11-07-2019, 02:54 AM
#5045
I saw your headers - nice pieces and well modified.
I agree with you in that my butt dyno is probably not in that great 'alignment' with realistic power numbers, but would you have seen better flow, lower IAT numbers with a 1/4" bigger TB? I was not aware of the ongoing debate and my issue is around my gummed up TB, no doubt due to the fact that it ia a) 15 years old, and b) previous owner was not at all hard on the car - I mean, when I took the car, there was oil separation build up at the top of the filler tube, so it was rarely, if ever, run hard an put away wet.
In a past build, I took a B18C5R Honda engine apart and rebuilt it with all the super sexy Japanese parts I could find, ported the heads, lightened the flywheel, put 9200rpm cams and supporting hardware in it and went to the dyno. Imagine my disappointment, when after all this work, the car only put down 210whp. I was floored (and pretty pissed) until I started looking at restriction in the intake system. I had machined my own velocity stack and fabricated my own intake snorkel, but then I started looking at the TB, which was only 62mm, no fitted to an engine that cut the fuel at 9500rpm.
I fitted a 70mm TB and bam! 230whp, 265/70ish at the crank, with a dead flat AFR without it getting rich from 6500rpm +. It was my first real lessen in flow - it didn't matter that my heads were now flowing 250cfm at .5/' lift if I couldn't feed them.
My thinking was that not only would I address the problem with the gummed up TB, by removing about a 1/4" restriction, at the TB, I would be able to flow extra air, lean it out a bit and address the rich condition - of course, I may in fact be wrong in the Porsche world, but it sure made the world of difference in the Honda world.
Now, I want to dyno it.
I agree with you in that my butt dyno is probably not in that great 'alignment' with realistic power numbers, but would you have seen better flow, lower IAT numbers with a 1/4" bigger TB? I was not aware of the ongoing debate and my issue is around my gummed up TB, no doubt due to the fact that it ia a) 15 years old, and b) previous owner was not at all hard on the car - I mean, when I took the car, there was oil separation build up at the top of the filler tube, so it was rarely, if ever, run hard an put away wet.
In a past build, I took a B18C5R Honda engine apart and rebuilt it with all the super sexy Japanese parts I could find, ported the heads, lightened the flywheel, put 9200rpm cams and supporting hardware in it and went to the dyno. Imagine my disappointment, when after all this work, the car only put down 210whp. I was floored (and pretty pissed) until I started looking at restriction in the intake system. I had machined my own velocity stack and fabricated my own intake snorkel, but then I started looking at the TB, which was only 62mm, no fitted to an engine that cut the fuel at 9500rpm.
I fitted a 70mm TB and bam! 230whp, 265/70ish at the crank, with a dead flat AFR without it getting rich from 6500rpm +. It was my first real lessen in flow - it didn't matter that my heads were now flowing 250cfm at .5/' lift if I couldn't feed them.
My thinking was that not only would I address the problem with the gummed up TB, by removing about a 1/4" restriction, at the TB, I would be able to flow extra air, lean it out a bit and address the rich condition - of course, I may in fact be wrong in the Porsche world, but it sure made the world of difference in the Honda world.
Now, I want to dyno it.
Again, would love to see a real legit dyno comparison. You should do it. PM me if you'd like some tips for doing dyno runs with good repeatability and ensuring comparable dyno conditions to give accurate results.
Last edited by powdrhound; 11-07-2019 at 03:28 AM.
11-07-2019, 12:23 PM
#5046
@2fcknfst if at all possible, please dyno it before and after. I had already installed the larger TB and Comp IPD plenum by the time I caught wind of the doubts regarding the HP claims. I did so many other things to my motor "while it was out" I have no particular frame of reference for the pieces. They were sold to me by the best, as part of a larger setup which had a net cumulative hp gain of roughly 185hp over stock. My instinct tells me the addition of the plenum does not net any gains on the top end but most likely increases the mid-range power of the motor. Do the dyno for the forum, get tips from Powdrhound prior to.
11-07-2019, 01:08 PM
#5047
I would also guess that the larger TB alone does not make a big difference, hell even bigger TB + plenum probably don't make a difference, because the car is turbocharged. For a n/a motor, it makes sense to put bigger TB on, and that has been proven in the muscle car world many times. With boost, that air is compressed and being shoved through the piping, and at 63-68mm it's just not a restriction point. In my experience with turbocharged cars, I have seen some big gains with different style intake manifolds, and I bet if there was room up there we would also be able to realize some gains by changing them.
11-07-2019, 02:27 PM
#5048
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@2fcknfst if at all possible, please dyno it before and after. I had already installed the larger TB and Comp IPD plenum by the time I caught wind of the doubts regarding the HP claims. I did so many other things to my motor "while it was out" I have no particular frame of reference for the pieces. They were sold to me by the best, as part of a larger setup which had a net cumulative hp gain of roughly 185hp over stock. My instinct tells me the addition of the plenum does not net any gains on the top end but most likely increases the mid-range power of the motor. Do the dyno for the forum, get tips from Powdrhound prior to.
I would also guess that the larger TB alone does not make a big difference, hell even bigger TB + plenum probably don't make a difference, because the car is turbocharged. For a n/a motor, it makes sense to put bigger TB on, and that has been proven in the muscle car world many times. With boost, that air is compressed and being shoved through the piping, and at 63-68mm it's just not a restriction point. In my experience with turbocharged cars, I have seen some big gains with different style intake manifolds, and I bet if there was room up there we would also be able to realize some gains by changing them.
It is an interesting topic; I can see the law of diminishing returns coming into play when folks build efficient 4.0s like John's - headwork, cams, monster turbos, nice ICs - when the power level is so high, I too suspect it would be hard to see improvement (incrementally) for a bolt on plenum if there is still restriction elsewhere in the intake tract.
So, going to have to carve out some time and find a dyno...
11-07-2019, 02:42 PM
#5049
Yes, I am now intrigued, but I will have to find the time to get it done. I'll let everyone know when I can organize it.
I would tend to agree with you on that too - I cannot math it out right now, but if John's 4.0 is making close on (or more than) 800 crank hp @ 18.3psi of boost, that tells me he is flowing some serious air, and that the restriction in his intake tract is somewhat irrelevant due to other efficiencies he has engineered into his build. I have always imagined that with pressurized mills, there is always some on throttle pressure behind the TB as you don't drive around at WOT 100% of the time, so making that air move in the most efficient, least restrictive way possible will do nothing but help. However, this appears to be the source of this debate and different schools of thought. Yes, I can see (now) why a gaping hole of a TB is good for a mill that is turning 9000+RPM; I can also see why having a smaller orifice for pressurized air to move through would keep the velocity of said air up, resulting in less lag, but I do believe it would also heat up, or at least add heat to the IAT.
It is an interesting topic; I can see the law of diminishing returns coming into play when folks build efficient 4.0s like John's - headwork, cams, monster turbos, nice ICs - when the power level is so high, I too suspect it would be hard to see improvement (incrementally) for a bolt on plenum if there is still restriction elsewhere in the intake tract.
So, going to have to carve out some time and find a dyno...
I would tend to agree with you on that too - I cannot math it out right now, but if John's 4.0 is making close on (or more than) 800 crank hp @ 18.3psi of boost, that tells me he is flowing some serious air, and that the restriction in his intake tract is somewhat irrelevant due to other efficiencies he has engineered into his build. I have always imagined that with pressurized mills, there is always some on throttle pressure behind the TB as you don't drive around at WOT 100% of the time, so making that air move in the most efficient, least restrictive way possible will do nothing but help. However, this appears to be the source of this debate and different schools of thought. Yes, I can see (now) why a gaping hole of a TB is good for a mill that is turning 9000+RPM; I can also see why having a smaller orifice for pressurized air to move through would keep the velocity of said air up, resulting in less lag, but I do believe it would also heat up, or at least add heat to the IAT.
It is an interesting topic; I can see the law of diminishing returns coming into play when folks build efficient 4.0s like John's - headwork, cams, monster turbos, nice ICs - when the power level is so high, I too suspect it would be hard to see improvement (incrementally) for a bolt on plenum if there is still restriction elsewhere in the intake tract.
So, going to have to carve out some time and find a dyno...
11-07-2019, 02:44 PM
#5050
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Those are pretty - are those Cup cams?
11-07-2019, 05:03 PM
#5051
11-07-2019, 05:07 PM
#5052
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Very nice indeed; are these production pieces? IE, can I buy them?
11-07-2019, 05:45 PM
#5054
11-07-2019, 06:29 PM
#5055
We are still using stock ECU so variocam remains liming redline to 7500. In order to go to 8400 will necessitate different lifters/cams which in turn will require a Motec ECU. Project for end of next year. We will run the engine as is with the Schrick cams in the interim.