Some of you probably heard about the SR20 VE ? And the frequently made Frankenstein SR20VE+T ? But there is a non common and rare version of SR20VET from Nissan directly. This engine theoretically produce 280ps (276bhp) from the manufacture. Its literally the most powerful version of the SR platform ever made! Let’s see the engine and the components.
The engine itself is a axial engine coupled on a AWD automatic transmission ( never done in manual ). Many parts differ in shape and function compared to the VE. One of the most important things are the VVL solenoid. This version only have variable valve lift on the intake cam. And the solenoid position is really more practical due to the angle mounting position, this add more clearance for any kind of transplantation of the engine to an other model of chassis.
The injection system differ than the other version of SR20. This system is top feed styled and operate high independence solenoid. Normally Nissan using low independence injector in most of the top feed setup, like in the pulsar GTi-R. The injectors used on the VET are high independence and the possible volume provided by them is 444cc at 3bar
The exhaust manifold on the particular model is really better designed for maximum velocity. The shape of the runners are really more like it should be to get more speed of the post combustion gas. But ! There is a big but, Nissan engineers made several notch to the runners to get clearance for the bolts, big notch. For example, the first cylinder exhaust port is reduced the way that we can’t enter a finder in the manifold. This will cause a resistance that increasing back pressure on only one cylinder and a lot flow distortion at full boost.
The ports have a mismatch about 4mm on the exterior side of the cylinder 1 and 4, like the manifold stretch back. That’s a lot of handicap for a “performance” engine.
The exhaust ports have the same pattern than all the SR20’s manifold, that’s good for performance mods and engine adaptation on an other chassis. In this particular case, we try to install an S13 bottom mount OEM manifold. We can also think about using flanges to design custom manifold ( available here )
The intake manifold is really more efficient than DE & DET versions. The intake have shapes inside to improving air flow and velocity without creating any turbulence. The aluminum cast is really high quality, that make modification and welding much easy to do. The intake plenum itself is really more higher than all the other version of the D’s, making engine swaps a little bit more difficult, because the VE & VET intake manifolds have a different pattern and port shape than the other SR20. Both VE and VET have normally the same pattern.
In this case, we try to simply turn the intake plenum entry from right to left. But the two middle ports are a little offset and make the operation impossible. So we scan the ports, to get a perfect match on the computer and designing our own velocity stack to weld directly to the OEM runners. The runner length stay the same but we add a little more length to improve the flow by adding velocity cones. We also create a simple plenum that pointing the throttle a little to the ground to help future clearance issues and possibly help the air flow inside the plenum itself.
The throttle body of the VET is drive by an electronic motor, the servo motor system generally add pedal lag and are not specially effective and cost more to adapt in performance application. So we install a S13 Sr20DET throttle body that is drive by cable.
The transmission on this model is automatic, this causing problems to most of conversions. A manual transmission is normally most desirable when you swap an engine. On this engine some of the accessories are re-localized. We talking about the starter that is moved upward to give more room to the FWD differential. The SR20DET flywheel pattern is bolt on. But the ring gear for the starter is not compatible, the DET one is smaller than the VET, the only reason of that is the re-localization needed for differential clearance.
We remove the VET ring gear on the automatic plate, mill the DET gear to the inner diameter of the VET one. Press the VET ring on the modified DET ring and welded them together. Now the engine can start and he’s ready to receive a manual transmission.
The bellhosing pattern is half the same of the DET. So we have to modify a RWD SR20 transmission or create a custom adapter for this transmission. But the 280ps produced by the VET is really too near of the RWD SR transmission break limits. So we opt for a stronger solution, a Nissan CD transmission from 350Z & G35. Normally capable to hold a lot of power. So we create a complete transmission adapter for this VET.
The Turbocharger on this engine is not advanced as the Gt28 with ball bearing found on S15 version SR20DET. This engine only have a bushing bearing and the trim is really small compared to the HP produced.
Many source affirm that the turbo used on the VET is a special billet wheel GT28 with ball bearings but this is absolutely false. The model used to pressurize the VET is a non-common version of the GT25. This turbo is generally designed to produce between 170 to 270 HP on 1.4L to 2.2L engines. The entire routing of the piping is really well done, the piping have good size transition before the turbo to improving high velocity. Smooth curves, improved for best flow intercooler and the throttle body right after the outlet of it, making this engine near lag free and using the most percents of efficiency as possible. The inlet flange of the turbine hosing is a normal T25 pattern, but the outlet pattern is not the same as normally found GT25. The flange shape is the same but using different pattern, possibly because of the catalytic converter bolted directly on the turbo that required more space than a regular downpipe.
The turbo exact model is GT2560S. This can be ordered with the new revision Garrett part number ( 715643-5002S ), previous version are ( 715643-0001, 715643-0002 ). Or at Nissan directly with this number ( 14411-8H601 ).
This particular engine using coil on plugs like most of the SR20 but only identical as the S14 and S15 and have specific spark plugs. These are produce by NGK but are not available outside Nissan. 3 model of spark plug are available, the difference is the temperature.
By default Nissan used the PLFR6A-9 ( 22401-8H616 ) but they have a hotter version PLFR5A-9 ( 22401-8H617 ) and a colder version PLFR7A-9 ( 22401-8H615 ).
You can order them normally at Nissan, they will order them from Japan.
In our case, the spark plugs on the engine we have will never good enough to get them back in place. The gap is way over the range ! ( see by youself )
VVL, what that mean? its simply the abbreviation of variable valve lift. The VET have a special cylinder head ( number 8H6 ), its a little different than a P12 head because only one cam is variable, there is a big difference between lobes. The smallest have 5mm and the VVL lobs have 6.75mm this is really big, about 26% lift difference. The exhaust cams get 6.5mm lobs.
The cams do not directly push the valves, there is rockers that will change the valve travel. The intake valve movement is 8.5mm on the base lobes and get 10.15mm on the bigger lobes. The exhaust always have 11.5mm. ( these values can need to be re-done a second time to be sure )
The compression ratio is normally 9.0:1
To be continued.