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Crash Course of the VH.  Basically, there are 3 types of VH.  They are






The VH45DE is the “king”, and was used in the Infiniti Q45 90-96, and the Nissan President 89-01.  The VH41DE was used in Japan only in the 90’s in cars such as the Y32 Cima, JPY32 J.Ferie (Basically an infiniti J30) and so forth. 


The VH41DE used in the 97-01 Q45 was very different.  It is not as strong as the VH45DE or JDM VH41DE, had log type intake and exhaust manifolds, and the internals were not as strong.  The crankshaft bearing girdle was lost, as well as many other of the features we love about the VH’s.


The major difference between the VH45DE and JDM VH41DE is the stroke is simply shorter.  Rods and pistons are the same, difference is in the crankshaft.  VH45 internals can be swapped into a VH41.  The VH41 have slightly better heads due to a duplex timing chain setup, but the heads are otherwise nearly identical.  Heads can flow nearly 500HP.



Interchangeable Parts


The VH45 uses 370cc injectors, identical to the ones used in the VG30DETT and SR20DET.  The VH41 uses 270cc injectors which are identical to the KA24 and VG30DE injectors.  With that being said, it is possible to use 555cc or 740cc NISMO side feed injectors on a stock VH45 fuel rail.  Obviously, tuning would be required.


Currently, VH Power is researching the ability to use VQ30DET pistons as decompression pistons for boost.  They have the same bore and wrist pin measurements, and very similar compression height, and have a dished design. 


VH Power is also currently researching the use of valve springs from other motors for use in the VH.  The stock VH valve springs are very weak at a measly 120lb, sufficient for a stock Q45 but not for a race motor with 15lbs of boost!


How far can I take a VH?


One of the best things about the VH is how far they can be taken with little to no modification.  The stock pistons, which are of a flat top design with recesses for the valves are not very prone to detonation, which means they can be boosted very safely with no internal modification.  Of course, we all are familiar with the legendary internals that Nissan gave us back in its prime, and the VH is no slouch.  It seems that other things break easier than the insides of a VH.


In New Zealand, many of the Super Stock racecars use JDM VH41’s.  They run those things to about 9000 RPM and 500HP on basically stock motors.  Modifications include mostly things like headers, intake and cams/valve springs (note stock hydraulic adjusters are retained). 


VH Power has not been made aware of anyone boosting a VH past its stock injector HP rating, which is around 450HP, so its hard to say right now how much boost one could run with larger injectors and a really good tune.  It seems everyone who blows up boosted VH’s loses them to tuning, because on a high compression motor detonation will kill it very quick.  Properly tuned vehicles have been known to see lots of boost and a lot of HP, but the line where adding more fuel does nothing to prevent detonation is not yet known.


Even HIGH MILES motors can take a beating if they were properly maintained.  If the oil was changed regularly, a motor with 200k could be about as good as a motor with 120k.  They simply don’t wear out that fast.  However, if the motor was overheated or looks really dirty inside then avoid it because it will probably need redone.  Clean examples can be imported from Japan very often, so its usually not cost effective to rebuild but rather find a clean, complete motor.


Quirks/Problems with the VH


The VH45DE was the motor used in the Infiniti Q45 luxury vehicle.  Since this was Nissan’s first attempt at a luxury vehicle, and stiff competition from Toyota and Honda, as well as the Germans, they had to be sure to do it right.  Most of the problems with VH’s are all age related.  Hoses get brittle, knock sensors go bad, and so forth, all of which can be replaced with factory parts fairly easy.


It must be stated that all 90-93 VH45’s need to check the timing chain guides.  Like the KA motor, the chain guides were made of plastic and when they break they can throw the chain off the camshaft and destroy the motor. 


The major problem with VH45’s is the injectors, mainly due to the higher ethanol content in today’s gasoline.  In areas of where this is not a problem you see much less injector related issues.  Most Q45 injector issues occur in California, Arizona and New York, as their gasoline has higher concentrations of ethanol.


The MAF on the VH45 can also be somewhat troublesome, causing really weird driveability issues.  Generally, VH45 MAF’s cannot be rebuilt or saved, you must replace with a working used or new.  Knock sensors also fail with age, they can be easily tested and the harness should also be replaced anytime the sensors are being replaced.  One can easily inspect the knock sensors and if there are cracks anywhere on them, they are probably bad.  Also, if the knock sensors look like they have melted, the engine has been overheated severely and further action should be taken before the motor is damaged further.



Closed deck engine
6 bolt mains, 2 are crossed
274.22CI, 4494CC
Bore/stroke- 93x82.7mm (3.66/3.256in)
Multiport fuel injection with equal length runners
370CC injectors
2 compression piston rings
1 oil piston ring
10.2:1 Compression Ratio
Individual runner exhaust manifolds

- Forged steel crankshaft.
- Forged steel connecting rods.
- Full-length main bearing cap girdle.
- Lightweight, floating pistons with molybdenum coating.
- Sodium-filled exhaust valves (90-92 motors only).
- Cross-flow cooling system.
- Hydraulic lash adjusters.
- Single-row silent timing chain.
- Coil-on-plug ignition system.
- Roller rocker arms for reduced friction.
- Variable Valve Timing.
- Redline of 6900 rpm.
- Compression ratio of 10.2 to 1.
- Bore of 93 mm and stroke of 82.7 mm.
- Dimensions: 890 mm(L) x 740 mm(W) x 725 mm(H).


Lift = 9.9mm
Duration = 248°
38mm diameter

Lift = 9.9mm
Duration = 248°
32mm diameter

Some Measurements and Pictures

Here are some measurements from various components in the VH45.  Thanks to “defrag010” on the forum for providing these. 


* all measurements are +/- .005"


Bottom End

Bore = 3.635" / 92.1mm
Wristpin = .865" / 22mm
Compression height = 1.257" / 32mm
1st and 2nd Ring thickness = .074" / 1.88mm / (~5/64")
Crown to first ringland distance = .235"
First tingland to second ringland distance = .125"
Small end gap = .985"

Piston pic 1
Piston pic 2
Piston pic 3

*bushed small end, with forced pin oiling and a piston oil squirter on rod*
Length (center of bigend to center of small end) = 5.8"
Big end width = .865"
Small end width = .700"
Big end bore = 2.160"

Rod pic 1


Intake valve head size = 1.501" / 38.15mm (no oversize possible w/o shrouding)
Exhaust valve head size = 1.300" / 33mm (oversize possible)
Rocker ratio = 1.6
Exhaust camshaft base circle = 1.175"
Exhaust camshaft total circle at centerline = 1.392"
Exhaust camshaft lobe lift = .217"
Exhaust valve lift w/ 1.6 rockers = .347"

Valve stem seals (SBI part numbers, viton, metal clad style)
90-95 = 122-1239
96 = 122-1264
90-96 = 122-1159

-Intake ports are EXCELLENT. They are concentric all throughout, low seat/port floor angle, and there is literally no casting flash or ridges at all anywhere inside the intake ports. From the port opening to the bowel is a straight cylinder, meaning if one wanted to port the intake side all he/she would have to do is put the head on a press and bore out each intake port until you hit the bowl, and then blend. They literally do not need any porting at all, unless you want to make the runner volume larger by boring the ports out.

Onto the measurements...

Spring installed height = 1.455"
Zero lift Coil Bind = .930"
Seat pressure at installed height = ?? (spring tester was being used while I had free time, maybe later)
-Springs are large enough and soft enough to find a stiffer alternative OEM spring off of another type of head that will give enough pressure needed for either superhigh rpm or if you want to run some bigger cams. I messed around and a stock SBC spring fits into the VH45 spring cup and retainer Perfectly, except the installed height and coil bind of the SBC spring were too tall for use on a VH.

-stem diameter = .270"
-height = 4.05"
-stem diameter = .310" / 5/16"
-height = 4.45"
-sodium filled on exhaust only
-7 degrees
-diameter = .400"
-height = .280"
-bead type = round
-bead diameter = .075"

I also took measurements of the cam cap bolts so that I can have some made that are low profile 5-point heads vs. the crappy 1/4" torx. I twisted off two different snapon torx bits getting these caps undone, so I think some 5-point head bolts will be nice to have incase you break one off and have to drill the head off of the torx bolt like I did.

-height = 1.56"
-shank diameter - .250"
-head diameter = .540"
-head height = .092"
-thread = m6x2.0

Links to publish



Nitrous and VH45DE

More camshaft information

A chain guide thread but lots of good information

Supercharged VH45DE in a skyline

VH45DE in a 240

More power related info


Forged pistons

Assorted good information

VH45 in a skyline

Nitrous and VH45DE