USDM VH41 issues......

[JMT-Z]

I have been reading on this site for quite some time and all I have found are random posts here and there about how the JDM VH41 is superior in construction to the USDM VH41, yet I cannot find the source of this statement. Would someone please enlighten me with the differences that they KNOW, not what they heard someone else tell someone else. Im pondering doing a swap using one of the VH-series of engines in my Z32.

[SuperHatch]

I have been reading on this site for quite some time and all I have found are random posts here and there about how the JDM VH41 is superior in construction to the USDM VH41, yet I cannot find the source of this statement. Would someone please enlighten me with the differences that they KNOW, not what they heard someone else tell someone else. Im pondering doing a swap using one of the VH-series of engines in my Z32.

Well, lets start with the block...

The Block casting is the same on all VH41, USDM, JDM, RWD, AWD, doesn't matter, the block casting is the same. All versions have the same crank, rods, pistons, and oil pan (which is cast AL btw). The AWD oil pan is obviously different. The USDM VH41 does NOT have the block girdle connecting the mains like the JDM does.

The heads...

Well, where do we start? Nothing is the same JDM to USDM. Take the late oval port VH45 heads and update the design to incorporate the duplex timing chain setup of the VH41 and you have JDM VH41 heads. The USDM heads have smaller ports, different cam cap setups, a single chain on the cam gears, and other odds and ends that make them inferior (from a performance standpoint) to the JDM VH41 heads.

Induction...

The JDM VH41 uses a spider style intake manifold just like the VH45, the USDM VH41 does not. The JDM VH41 uses "header" style exhaust manifolds like the VH45, the USDM VH41 uses a cast log-style manifold.

Accessories...

The USDM and JDM VH41 both have their alternators in the valley between the cylinder banks. The PS pump and AC compressor are on opposite sides as the VH45 and mounted higher up. The VH41 accessory layout makes it much more desireable for a swap into a Z32 since the lines are in the correct locations. The accessories are also mounted higher which gives more swaybar clearance. However, the AL pan is not as easily modded for crossmember clearance as the steel pan of the VH45 is, and no, the pans can't be interchanged. Bolt pattern is different.

How do I know all of this? I have now owned 5 VH45s and one USDM VH41, so I speak from first hand knowledge of those motors. The JDM VH41 information I've mentioned is what I've gathered from reading this forum and internet sites.

USDM and JDM

[Mettler]

Nice, Superhatch, though to add to your points... The JDM VH41 does not have header style exhaust manifolds, it has crummy log style manifolds.

Oh... and the Y32 generation JDM VH41 is the only VH engine to run duplex timing chains, the USDM version (Y33 gen) only has simplex. The difference in timing chain setup between the VH41s & VH45s gives the VH45 a wider front cover with a wider flange casting on the head due to the larger cam sprockets.

The VTC system works differently on a VH41 compared to the VH45... the VH45 has a solenoid valve mounted to the front of the intake camshaft VTC drum on each side... opening the drum to relieve oil pressure.

On the VH41, the solenoid valve is screwed into the side of the head and blocks/opens an oil gallery through to the first cam bearing journal and the VTC drum itself is filled & pressurised through here.

I think both 41 & 45 VTC drums are filled with oil from there, but the 41 blocks oil supply to the drum as opposed to relieving pressure with oil bypass.

Can't fault your post other than that

Oh, and I know these things because I have pulled apart various VH engines myself, and have service manuals for G50 & Y33 with exploded views of the engines.

[JMT-Z]

Well this is exactly what I was looking for. Thank you for all the details.

[Kirby260]

Move to have information from this thread merged with the FAQ sticky....

Edit: While we are here. There are TWO versions of the JDM VH41. The first is the one SuperHatch and Mettler talk about, this came from Y32 series cars. The second is the Y33 version eluded to by Mettler. As far as I am aware it is very similar to the 'US VH41'.

Photos:Engine Cover

No cover

LH Valve Cover

Differences to Y32 VH41:-Different engine cover-Coils have integrated transistors (apparently???) No Power Transistor Units.-No coil covers-Different Head/Cam Chain Design-Single log type manifold

Modified by Kirby260 at 8:36 AM 11/14/2008

Modified by Kirby260 at 8:38 AM 11/14/2008
Modified by Kirby260 at 8:38 AM 11/14/2008

[koukimatt]

Sorry in advance for the thread necromancy.

The USDM and JDM VH41 both have their alternators in the valley between the cylinder banks. The PS pump and AC compressor are on opposite sides as the VH45 and mounted higher up. The VH41 accessory layout makes it much more desireable for a swap into a Z32 since the lines are in the correct locations. The accessories are also mounted higher which gives more swaybar clearance. However, the AL pan is not as easily modded for crossmember clearance as the steel pan of the VH45 is, and no, the pans can't be interchanged. Bolt pattern is different.

I believe gs14racer had to notch a frame rail (not sure which side) to fit a VH45 into his S14. Would using a VH41 block avoid that complication, due to the alternator and accessory pumps being mounted higher up?

Edit: Should have searched first about sourcing a block, already covered.


Modified by koukimatt at 11:32 PM 1/31/2009

[maxnix]

Nice, Superhatch, though to add to your points... The JDM VH41 does not have header style exhaust manifolds, it has crummy log style manifolds.

Oh, and I know these things because I have pulled apart various VH engines myself, and have service manuals for G50 & Y33 with exploded views of the engines.

The US market header is loggier than the JDM one.

And no Y33 (Cedric or Gloria) ever had a VH41DE, only certain models of the FY33 Cima and all FGY33 US 1997-2001 Q45.

[Mettler]

The US market header is loggier than the JDM one.

Pics! Hard to believe it can get much worse tbh!

[SaintlyCharBoy]

Mettler,I'm not sure what your manifolds look like, but '97 USDM manifolds remind me of Z32 manifolds in concept.

[maxnix]

Mettler,I'm not sure what your manifolds look like, but '97 USDM manifolds remind me of Z32 manifolds in concept.

Seems someone down under posted up a picture of the JDM headers and they had at least a hint of being a header. It had the spider manifold as I recall.

[Mettler]

Nah man, on the motor I had, they didn't have any hint of being a header, were more or less almost the same as that :/

Then again their design may vary based on what car they were packaged in... but I haven't seen any non log style VH41 headers myself.

[maxnix]

Nah man, on the motor I had, they didn't have any hint of being a header, were more or less almost the same as that :/

Then again their design may vary based on what car they were packaged in... but I haven't seen any non log style VH41 headers myself.

Well there is Impul, at least for RHD cars.

Someone posted some pictures that have a hint of separation, not like US market logs.

But nothing as good as VH45DE either. I guess one sould weld VH41DE flanges to VH45DE headers.