+1 How many liters is the stock manifold?
Intake manifold information
- Thread starter A.S. Motorsport
- Start date
The large plenums help make big dyno numbers, but for a FI vehicle, they hurt transient response with the extra volume of air that is required to pressurize from off/on boost. Most people are numb to this due to an inefficient turbo design. Especially on NSX's that don't lend themselves to a decent turbo layout. That's why people love the "throttle response" from a nice N/A build even though the peak power may not be there compared to a F/I build. It's just more fun live with on a long-term basis.
The Autowave and AMW turbo kits that place the compressor above the transmission are a nice layout in that regard. Then you can have minimal intake volume, minimal intake restriction, and tune your intake runner length for a desired RPM band with the least impact to throttle response. Variable runner length is a topic that has been discussed on here years ago. After personally going through a $20k engine rebuild, I am all for active designs that have the conservative fail-safe engine management programming built-in. That's the tricky part that people usually don't consider until it's too late
I now have:
* An active exhaust that ironically gets quieter and less-restrictive above 3k RPM. Got tired of the attention on the street!
* A variable geometry low-flow compressor that generates a P/R of 2 beginning at 3k RPM
* An active bypass valve for a high-flow compressor that keeps my P/R at 2 up until 7k RPM
* A methanol injection setup strictly to keep AIT under control without the need for a traditional intercooler
* And am working on a variable-length intake runner system utilizing a hacked-up OEM manifold.
All of the active systems are set up to fail in a safe state with my Series 2 engine tuning appropriately thought-out.
My point is: You need to have some active system in the intake to get the best of power and driveability. Same thing with anything really. That's why you have active intake, active exhaust, active aero, active suspension, etc.... There is no single perfect design, even for F/I.
Dave
The Autowave and AMW turbo kits that place the compressor above the transmission are a nice layout in that regard. Then you can have minimal intake volume, minimal intake restriction, and tune your intake runner length for a desired RPM band with the least impact to throttle response. Variable runner length is a topic that has been discussed on here years ago. After personally going through a $20k engine rebuild, I am all for active designs that have the conservative fail-safe engine management programming built-in. That's the tricky part that people usually don't consider until it's too late
I now have:
* An active exhaust that ironically gets quieter and less-restrictive above 3k RPM. Got tired of the attention on the street!
* A variable geometry low-flow compressor that generates a P/R of 2 beginning at 3k RPM
* An active bypass valve for a high-flow compressor that keeps my P/R at 2 up until 7k RPM
* A methanol injection setup strictly to keep AIT under control without the need for a traditional intercooler
* And am working on a variable-length intake runner system utilizing a hacked-up OEM manifold.
All of the active systems are set up to fail in a safe state with my Series 2 engine tuning appropriately thought-out.
My point is: You need to have some active system in the intake to get the best of power and driveability. Same thing with anything really. That's why you have active intake, active exhaust, active aero, active suspension, etc.... There is no single perfect design, even for F/I.
Dave
Damn good to have you back Dave! Hope the vacuum exhaust valve worked out for you. Ironically I have a 3" version that I'm probably not going to use anymore
Thanks Regan! Yeah, pretty busy with stuff lately....
I don't have a great vacuum source with boost building at 2000 RPM so I couldn't use it. Would you like it back? I'm using my electric valve to open/close still. It's fine now since my open mode is the free-flowing quiet setup. Yeah, completely backward than before! The NSX is the one I like to drive the most, and you can't enjoy it discreetly on the street with that sweet loud exhaust....
Now big-blocks on the other hand I like loud and obnoxious....
I don't have a great vacuum source with boost building at 2000 RPM so I couldn't use it. Would you like it back? I'm using my electric valve to open/close still. It's fine now since my open mode is the free-flowing quiet setup. Yeah, completely backward than before! The NSX is the one I like to drive the most, and you can't enjoy it discreetly on the street with that sweet loud exhaust....
Now big-blocks on the other hand I like loud and obnoxious....
dont need it back anytime soon Dave. glad to see you back here. im with you... i want my nsx to be street and driver friendly. update you build thread sometime. hope to catch up w/ you more soon
Minimizing the volume of the intake manifold in order to sharpen the throttle response is also what Honda did with the naturally aspirated 125 PS / liter S2000. When it came out in 1999, Honda described their thinking regarding the intake manifold as follows:
"Ways to Achieve Fast Engine Response:
The variable-intake plenum chamber volume/length effectively uses the optimum pressure pulsation in the intake system to achieve high volumetric efficiency in a wide engine speed range. However, the effectiveness is obtained after the intake valves are closed in the case of the multi-cylinder engine, and there is time delay in achieving high volumetric efficiency. Therefore, the variable system is not appropriate for the sports car engine which requires fast engine response.
For the F20C engine, an approach was taken to reduce the volume downstream from the throttle valve, yet the maximum target power could be achieved. Intake port diameter and length were reduced as much as possible. An independent straight port was used for each cylinder. This helped intake pressure to respond quickly to the movement of the throttle valve. As shown in Figure 1.1.6, the intake manifold volume could be reduced to the level of a 1.6-liter engine.
The compact intake manifold effectively increased the response of intake manifold pressure when the throttle was closed, as shown in Figure 1.1.7. The pressure decreased 100 msec faster than the F20B which had a variable intake system. Combining the compact intake volume with other factors such as a lighter flywheel, optimized fuel injection and ignition timing control, the engine speed response increased by 18 percent, as shown in Figure 1.1.8, when the throttle was fully opened from the closed position."
"Ways to Achieve Fast Engine Response:
The variable-intake plenum chamber volume/length effectively uses the optimum pressure pulsation in the intake system to achieve high volumetric efficiency in a wide engine speed range. However, the effectiveness is obtained after the intake valves are closed in the case of the multi-cylinder engine, and there is time delay in achieving high volumetric efficiency. Therefore, the variable system is not appropriate for the sports car engine which requires fast engine response.
For the F20C engine, an approach was taken to reduce the volume downstream from the throttle valve, yet the maximum target power could be achieved. Intake port diameter and length were reduced as much as possible. An independent straight port was used for each cylinder. This helped intake pressure to respond quickly to the movement of the throttle valve. As shown in Figure 1.1.6, the intake manifold volume could be reduced to the level of a 1.6-liter engine.
The compact intake manifold effectively increased the response of intake manifold pressure when the throttle was closed, as shown in Figure 1.1.7. The pressure decreased 100 msec faster than the F20B which had a variable intake system. Combining the compact intake volume with other factors such as a lighter flywheel, optimized fuel injection and ignition timing control, the engine speed response increased by 18 percent, as shown in Figure 1.1.8, when the throttle was fully opened from the closed position."
A visual for ^^^
the large plenums help make big dyno numbers, but for a fi vehicle, they hurt transient response with the extra volume of air that is required to pressurize from off/on boost. Most people are numb to this due to an inefficient turbo design. Especially on nsx's that don't lend themselves to a decent turbo layout. That's why people love the "throttle response" from a nice n/a build even though the peak power may not be there compared to a f/i build. It's just more fun live with on a long-term basis.
The autowave and amw turbo kits that place the compressor above the transmission are a nice layout in that regard. Then you can have minimal intake volume, minimal intake restriction, and tune your intake runner length for a desired rpm band with the least impact to throttle response. Variable runner length is a topic that has been discussed on here years ago. After personally going through a $20k engine rebuild, i am all for active designs that have the conservative fail-safe engine management programming built-in. That's the tricky part that people usually don't consider until it's too late
i now have:
* an active exhaust that ironically gets quieter and less-restrictive above 3k rpm. Got tired of the attention on the street!
* a variable geometry low-flow compressor that generates a p/r of 2 beginning at 3k rpm
* an active bypass valve for a high-flow compressor that keeps my p/r at 2 up until 7k rpm
* a methanol injection setup strictly to keep ait under control without the need for a traditional intercooler
* and am working on a variable-length intake runner system utilizing a hacked-up oem manifold.
All of the active systems are set up to fail in a safe state with my series 2 engine tuning appropriately thought-out.
My point is: You need to have some active system in the intake to get the best of power and driveability. Same thing with anything really. That's why you have active intake, active exhaust, active aero, active suspension, etc.... There is no single perfect design, even for f/i.
Dave
Makes complete sense.
Ok so i have looked into this and no one in New Zealand does 'Extrude Hone' price you pay for living here i suppose, so getting the spare one done here and comparing back to back on the same day doesn't look like i can do that.
To those that are interested, I have installed the intake manifold on my NSX. I am doing the final fuel delivery tid bits and then it's Dyno timeCustomer cars come first so as soon as I have time to get my results I will fill everyone in.
The suspense is killing us. Hope your customers are all happy now and you find the time to visit the Dyno to finish this "very interesting" project.
Also waiting anxiously... Need moar power now!
No worries, I just finished my twin pump setup and fuel lines, etc. The car is running and I am test driving it this holiday weekend! So long as there are not any problems I will dyno the car this coming week
- - - Updated - - -
Indeed! We all do hahaha
Update:
I drove the car around all weekend and everything is working as it should. I am finishing up a few customer dyno appointments and then I will throw mine on for results. Here is a link to a picture of the install:
https://www.facebook.com/dmsperform...4567379960615/679747032109311/?type=1&theater
I drove the car around all weekend and everything is working as it should. I am finishing up a few customer dyno appointments and then I will throw mine on for results. Here is a link to a picture of the install:
https://www.facebook.com/dmsperform...4567379960615/679747032109311/?type=1&theater
Looks good, cant wait to see the results
Well, dmscrx --- I have known a number of women over the years --- but none of them were a bigger tease than you. lol.
Hahahaha
Hilarious
he has a valid point...
it does look good in the car though, better looking than what it looked like on the bench being made
it does look good in the car though, better looking than what it looked like on the bench being made
So what did it make?
I am going to be on the dyno today. I will post results I promise!
I have finished the first set of runs for this manifold and I am fairly happy with the results. I am going to start a new thread with all of the info and a few pictures/dyno charts to start sometime this evening. Sorry to the OP for butting into this thread
Lol one final tease
I'll just leave this here
I sketched what a cross section of NSX cylinder heads would look like with straight intake runners angled a few different ways.
Angling straight intake runners 30-35° from vertical in an NSX engine will likely make the transitions into the cylinder heads smooth enough that little or no flow separation occurs, the runners will aim at the valve stems like in a Ferrari 458, and those angles should give the injectors enough room to shoot straight at the backs of the intake valves.
However, the bellmouths for the two banks of cylinders will get quite close to each other at those runner angles. Would that have a negative impact on gas dynamics? If more distance between the runners' bellmouths is beneficial, slightly curved intake runners like those used in the Ferrari F430 and Toyota 2GR-FSE engines would allow for smooth transitions into the cylinder heads AND more distance between the intake bellmouths.
It looks like one of the design goals of the OEM manifold was to keep the NSX beneath the old 280 PS limit. It would be great if there were an intake manifold that was really optimized for naturally aspirated NSXs. However, without some serious CFD software and ideally, testing, it's going to be hard to know what cross sections and volumes are best for what rpm and flow rates (horsepower).
I spoke with Freddy at Wilson Manifolds and he said they have all the CFD programs and experience to design a custom intake manifold optimized for whatever rpm range, horsepower target (n/a or turbo), etc. you want. They would charge USD 5500-6000 for the first manifold and then USD 3600-4200 for each additional copy. So about USD 2000 for the design and the rest for fabrication. It would be cool to get a really good n/a manifold designed and optimized using CFD and then printed on a 3D printer. I don't think Wilson Manifolds use 3D printers yet, though.
Angling straight intake runners 30-35° from vertical in an NSX engine will likely make the transitions into the cylinder heads smooth enough that little or no flow separation occurs, the runners will aim at the valve stems like in a Ferrari 458, and those angles should give the injectors enough room to shoot straight at the backs of the intake valves.
However, the bellmouths for the two banks of cylinders will get quite close to each other at those runner angles. Would that have a negative impact on gas dynamics? If more distance between the runners' bellmouths is beneficial, slightly curved intake runners like those used in the Ferrari F430 and Toyota 2GR-FSE engines would allow for smooth transitions into the cylinder heads AND more distance between the intake bellmouths.
It looks like one of the design goals of the OEM manifold was to keep the NSX beneath the old 280 PS limit. It would be great if there were an intake manifold that was really optimized for naturally aspirated NSXs. However, without some serious CFD software and ideally, testing, it's going to be hard to know what cross sections and volumes are best for what rpm and flow rates (horsepower).
I spoke with Freddy at Wilson Manifolds and he said they have all the CFD programs and experience to design a custom intake manifold optimized for whatever rpm range, horsepower target (n/a or turbo), etc. you want. They would charge USD 5500-6000 for the first manifold and then USD 3600-4200 for each additional copy. So about USD 2000 for the design and the rest for fabrication. It would be cool to get a really good n/a manifold designed and optimized using CFD and then printed on a 3D printer. I don't think Wilson Manifolds use 3D printers yet, though.
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