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This will be a write up of the evolution of the intake manifolds of the VQ, DE to Revup, but will also touch on a bit of the HR/VHR.
I believe that a sports car should have a linear powerband and take advantage of the entire rev range, it seems Nissan would agree because with every iteration they have closer and closer to a perfectly linear powerband. There will be some pictures comparing the DE and Revup lower plenums, some overlays of them and dynos of the DE vs Revup, and the HR vs VHR. The overlays are not perfect, but you get it lol.
The DE was a truck engine before it was put in a sports car, a quick glance at the dyno will show its truck roots. Because of this the manifold has different features than any other that came afterward. First off, the lower plenum have asymmetrical runners that are oval and have a gradual taper form the inlet of the air horns. Cylinders 1&6 have long runners, 2&5 have medium runners, and 3&4 have short runners. This leads to a more broad or "lumpy" powerband. Here are some measurements: DE
Runner upper length: cylinders 1&6 = 198mm / cylinders 2&5 = 185mm / cylinders 3&4 = 172mm
Runner upper width: air horn entry = 56mm / runners after taper ends = 47mm
Runner height: air horn and runner = 35mm
Lower surge tank depth from middle point = 26.7mm / distance from 1st air horn on right to plenum edge (at middle point) = 50mm
MREV2 clone (AKA DE) Lower surge tank Inside shot of how restricted the front cylinders are Left air horn machined for additional clearance Lower surge tank side view
With the introduction of the Revup Nissan switched to a lower plenum with symmetrical runners and never looked back, HR and VHR are symmetrical and have a rectangular shape.
Along with the new design they also shortened the runners to allow for better breathing in the higher rev range and minimize starvation to the front cylinders. Here are some measurements: Revup
Runner upper length: slight variations between 148-152
Runner upper width: air horn entry = 51mm / runners after taper ends = 47mm
Runner upper height: air horn entry = 45mm / runners after taper ends = 35mm
Lower surge tank depth from middle point = 35.4mm / distance from 1st air horn on right to plenum edge (at middle point) = 90mm
Revup lower plenum Notice how the air horns have changed up top to match the upper plenum for clearance Lower surge tank side view Lowe surge tank Space inside the right surge tank, much more space available for the front cylinder
HR
Upper manifold runner length = approximately 110mm
Now for some comparisons and overlay pics.
Comparison shot of both lower plenums HR plenum Overlay of DE and Revup plenums Stock DE vs Revup on same dyno Stock HR vs VHR on same dyno Average tuned DE Revup with MREV2 and spacer Tuned Revup Built DE with Kinetix Velocity
Call me crazy, but I truly believe the best option for the early cars is the Revup lower plenum, no starvation to front cylinders, no need for spacers and it will not fall on its face above 5500 rpm. Yes, you give up a bit of mid-range, but if I have learned ONE thing with the Kinetix Velocity is I want to be able to rev and not have the engine gasping for air. It should also be more boost friendly as well. I trust that Nissan had a reason for changing its design, and will be switching out my Velocity for it when I go for boost.
The DE was a truck engine before it was put in a sports car, a quick glance at the dyno will show its truck roots.
Im gonna challenge you on a few things - all with the intention of ‘food for thought’ … but I like where youre head is at and I like where youre going with this
Maybe … I’d have to go back and see but the VQ has been a wildly augmented engine that has been used in a wide variety of vehicles for Nissan. And in-reality (without much research) the only real consistent feature between the platforms that use the VQ will be the block (and more specifically, the engine architecture). Every vehicle from the 4liter frontier/pathfinder/xterra to the 3.5 maximas, and 3.5liter z/g and 3.7 z/g/q all use different intakes (and a variety of throttle bodies), different tuning, differnt internals, and even different aspirations.
Further - auto makers share engines with a variety of chassis… the best example is the LS found in a sports car and found in a pickup. I believe the original inline 6 corvette engine was from a chevy pickup. Nissan does this with the VK, Ford does this with the V8 and V6 engines. I would imagine toyota shares V8 engines between the truck and their large SUVs and higher end cars.
Originally Posted by DarkZ03
First off, the lower plenum have asymmetrical runners that are oval and have a gradual taper form the inlet of the air horns. Cylinders 1&6 have long runners, 2&5 have medium runners, and 3&4 have short runners. This leads to a more broad or "lumpy" powerband.
Yea - I believe this is for packaging … but know that nissan has ‘trimmed’ the fueling for each individual cylinder … so yes, cylinders 3 and 4 get the best airflow, 5 and 6 are next best and 1 and 2 are choked off … nissan has slightly reduced their fueling to account for this. I also think this is less of an issue at high engine speeds where the momentum of the airflow carries forward more efficiently than at lower engine speeds.
Originally Posted by DarkZ03
Call me crazy, but I truly believe the best option for the early cars is the Revup lower plenum, no starvation to front cylinders, no need for spacers and it will not fall on its face above 5500 rpm. Yes, you give up a bit of mid-range, but if I have learned ONE thing with the Kinetix Velocity is I want to be able to rev and not have the engine gasping for air. It should also be more boost friendly as well. I trust that Nissan had a reason for changing its design, and will be switching out my Velocity for it when I go for boost.
I think this is up to the end user. I believe the 1st gen DE intake is the best based on torque output. Torque is (ultimately) a measure of efficiency…Torque is the point in the rev-range where the engine can move the most amount of air in, and the most amount of air out. If the RevUp Plenum was a better, more optimal option, it would make more torque compared to the 1st gen DE.
Nissan manipulated the redline of the RevUp, along with adding exhaust cam timing, and a revised plenum to increase engine output to refresh the lineup. If the RevUp was truly a better engine, than it’d have lasted more than 1.5 years. And I speculate that nissan was not ready to release the HR engine in 2005/2006 and they knew they needed to do something to up the power to draw sales … and/or they were not ready in the early 2000s for exhaust variable valve timing but they needed to get a z chassis to production, so they only went with intake VVT. (All speculation from my part).
Im gonna challenge you on a few things - all with the intention of ‘food for thought’ … but I like where youre head is at and I like where youre going with this
Maybe … I’d have to go back and see but the VQ has been a wildly augmented engine that has been used in a wide variety of vehicles for Nissan. And in-reality (without much research) the only real consistent feature between the platforms that use the VQ will be the block (and more specifically, the engine architecture). Every vehicle from the 4liter frontier/pathfinder/xterra to the 3.5 maximas, and 3.5liter z/g and 3.7 z/g/q all use different intakes (and a variety of throttle bodies), different tuning, differnt internals, and even different aspirations.
Further - auto makers share engines with a variety of chassis… the best example is the LS found in a sports car and found in a pickup. I believe the original inline 6 corvette engine was from a chevy pickup. Nissan does this with the VK, Ford does this with the V8 and V6 engines. I would imagine toyota shares V8 engines between the truck and their large SUVs and higher end cars.
Yea - I believe this is for packaging … but know that nissan has ‘trimmed’ the fueling for each individual cylinder … so yes, cylinders 3 and 4 get the best airflow, 5 and 6 are next best and 1 and 2 are choked off … nissan has slightly reduced their fueling to account for this. I also think this is less of an issue at high engine speeds where the momentum of the airflow carries forward more efficiently than at lower engine speeds.
I think this is up to the end user. I believe the 1st gen DE intake is the best based on torque output. Torque is (ultimately) a measure of efficiency…Torque is the point in the rev-range where the engine can move the most amount of air in, and the most amount of air out. If the RevUp Plenum was a better, more optimal option, it would make more torque compared to the 1st gen DE.
Nissan manipulated the redline of the RevUp, along with adding exhaust cam timing, and a revised plenum to increase engine output to refresh the lineup. If the RevUp was truly a better engine, than it’d have lasted more than 1.5 years. And I speculate that nissan was not ready to release the HR engine in 2005/2006 and they knew they needed to do something to up the power to draw sales … and/or they were not ready in the early 2000s for exhaust variable valve timing but they needed to get a z chassis to production, so they only went with intake VVT. (All speculation from my part).
On the first, I am aware of what was changed to make the engine more adequate for a sports car.
The asymmetrical runners have nothing to do with packaging as far as I know, and you can see the overall dimensions are similar. The asymmetrical runners paired with the longer gradual taper lets there be a different VE for each "set" of cylinders with a given runner size. This is why the DE shows more torque than the Revup. I am not saying the Revup is perfect, but there is a reason they do not gain anything from a plenum spacer, they do NOT need it, it is built into the design. Symmetrical runners by design will have a certain range of VE and because of the length of the runners, it happens to be higher on the Revup, hence the lower low-mid and higher top end.
You are 100% correct though, this will be up to the end user and their preference of power output. the DE lower will yield more power before crossover and the Revup lower will yield more power at redline. This is because of the VE they are tuned for, but ultimately the DE lower is suboptimal and requires a spacer, the Revup does not. This will only get better with boost, put a big turbo or supercharger that has the potential to make power north of 5k and the DE will be suffocating the power output. As far as velocity and the front cylinders I will post a screenshot of what Motordyne has to say about the DE.
This will be a write up of the evolution of the intake manifolds of the VQ, DE to Revup, but will also touch on a bit of the HR/VHR.
I believe that a sports car should have a linear powerband and take advantage of the entire rev range, it seems Nissan would agree because with every iteration they have closer and closer to a perfectly linear powerband. There will be some pictures comparing the DE and Revup lower plenums, some overlays of them and dynos of the DE vs Revup, and the HR vs VHR. The overlays are not perfect, but you get it lol.
The DE was a truck engine before it was put in a sports car, a quick glance at the dyno will show its truck roots. Because of this the manifold has different features than any other that came afterward. First off, the lower plenum have asymmetrical runners that are oval and have a gradual taper form the inlet of the air horns. Cylinders 1&6 have long runners, 2&5 have medium runners, and 3&4 have short runners. This leads to a more broad or "lumpy" powerband. Here are some measurements: DE
Runner upper length: cylinders 1&6 = 198mm / cylinders 2&5 = 185mm / cylinders 3&4 = 172mm
Runner upper width: air horn entry = 56mm / runners after taper ends = 47mm
Runner height: air horn and runner = 35mm
Lower surge tank depth from middle point = 26.7mm / distance from 1st air horn on right to plenum edge (at middle point) = 50mm
MREV2 clone (AKA DE) Lower surge tank Inside shot of how restricted the front cylinders are Left air horn machined for additional clearance Lower surge tank side view
With the introduction of the Revup, Nissan switched to a lower plenum with symmetrical runners and never looked back. HR and VHR are symmetrical and have a rectangular shape, much like the airflow improvements seen in a raw performance intake manifold 6.7 Cummins.
Along with the new design they also shortened the runners to allow for better breathing in the higher rev range and minimize starvation to the front cylinders. Here are some measurements: Revup
Runner upper length: slight variations between 148-152
Runner upper width: air horn entry = 51mm / runners after taper ends = 47mm
Runner upper height: air horn entry = 45mm / runners after taper ends = 35mm
Lower surge tank depth from middle point = 35.4mm / distance from 1st air horn on right to plenum edge (at middle point) = 90mm
Revup lower plenum Notice how the air horns have changed up top to match the upper plenum for clearance Lower surge tank side view Lowe surge tank Space inside the right surge tank, much more space available for the front cylinder
HR
Upper manifold runner length = approximately 110mm
Now for some comparisons and overlay pics.
Comparison shot of both lower plenums HR plenum Overlay of DE and Revup plenums Stock DE vs Revup on same dyno Stock HR vs VHR on same dyno Average tuned DE Revup with MREV2 and spacer Tuned Revup Built DE with Kinetix Velocity
Call me crazy, but I truly believe the best option for the early cars is the Revup lower plenum, no starvation to front cylinders, no need for spacers and it will not fall on its face above 5500 rpm. Yes, you give up a bit of mid-range, but if I have learned ONE thing with the Kinetix Velocity is I want to be able to rev and not have the engine gasping for air. It should also be more boost friendly as well. I trust that Nissan had a reason for changing its design, and will be switching out my Velocity for it when I go for boost.
I agree. Switching to the Revup lower plenum is the better choice. It fixes front-cylinder starvation, supports high-RPM breathing, and provides a more linear, boost-friendly powerband, even if it sacrifices a bit of mid-range torque. For early VQ cars, it is clearly the smarter upgrade.
Intake Manifold Technical Info
