VH41/45 external differences

[Gareth]

Hello,

 

I'm currently searching for some info about VH engines, and after reading different articles about VH41/45 differences I got confused. Are there any external differences in both engines? I know that the following parts may be different:

 

- starter motor (mounted on left or right side of the block, depending on the steering column position - which one's better for a LHD car? Can they be swapped?)

- single chain (45) vs. double chain (41)

- plastic chain guides (45) vs. metal chain guides (41)

- square port heads (45) vs. round port heads (41)

- intake manifold (?)

 

Can anyone confirm this? Does the 41 block have lower deck height?

 

Thanks in advance.

 

Tony

[Gareth]

Um... Anyone?

[Clifton]

If you are still looking, some one on here would know. http://forums.nicoclub.com/zeroforum?id=193 If you find out the deck height please post here. I don't think there is a diffeence though as atleast one guy on there used a VH45 crank in a VH41.

[OlderThanMe]

I believe the Vh41 has the alternator in the middle top of the engine rather that on the passenger side as in the Vh45

[twoeightythreez]

I don't know if there's any difference but I'll quick measure it to see. I'll let you know tomorrow. I have a VH45 from my 95 Q that I was going to use in my S14 but yesterday pulled a VH41 out of a '98 Q that I'm going to use instead. It looks identical, but the 41 has a way more compact intake manifold (and exhaust manifolds, too!) and I believe the ignitors are built into it's coils. Also, the alternator is on top of the intake (like where a caddy 472's A/C compressor is) and the P/S pump is tucked under the right bank (so all I apparently need to do is use SOHC S13 power steering lines!)

ALso, the 41 I just got has 93K miles and my VH45, while reliable as the sun for me, has 188k miles on it. Choice made. I can always put the Vh45 crank in later.

The VH41 has slightly higher compresson then the 45 also (10.2:1 for the 45 and 10.5:1 for the 41)....it actually is only about 10hp shy of the 45....

I've heard that you can bore a VH to 98mm? Is that true? THis would open up options like using Buick 350 pistons or something.....

TO get back on subject, though, I believe all the people who are posting different external dimensions are not taking into account how much more compact the manifolds and accessories are on the 41. It's like Nissan saw an LS1 and liked what they saw, because that's what a VH41 looks like. A DOHC LS1.

 

Oh yes...here are the bore and stroke specs for the motors

 

VH45:

Bore 93mm Stroke 82.7mm

Comp. ratio 10.2:1

Rated HP 276 TQ 293

Vh41

Bore 93mm Stroke 73mm (yes a V-8 with a stroke of 2.99in.)

Comp. ratio 10.5:1

Rated HP 266 TQ 279

Looks to me as if deck height may be the same, and if it is possibly could build a long rod VH45 someday

While the horsepower numbers are not much different, despite the 45 having almost a quarter inch more stroke, I belive that nissan underated the 45's. A lot. I never dyno'd the Q (it sure could make that 4200lb sled fly though...and yes, they do weigh that much, the gross weight rating was nearly 5300lb. I verified this when I stripped my Q down and the shell alone..as in no interior, no glass, no brakes, no tires, no gas tank, no mechanicals, no wiring, and no doors, hood, or trunk, bumpers, or lights, weighed 1400lb...well OK I left the subframes in it....so the body still weighed half a ton....whew!) but I'm sure it would have belted out RWHP numbers close to the rated net HP, like the LS motors do.

The 41, probably makes what it says.

[OlderThanMe]

A vh45 has cast-in dry liners. You will need to get new liners installed for any sizeable overbore.

I am looking for a VH41 block to use if I can find it for more optimal alternator mounting.

 

Supposedly the VH45's power was rated without the variable timing... Worth another 20 or so hp.

 

The VH41 has the same deck height as the VH45...

[twoeightythreez]

1)Alternator located in engine valley area, with drive belts arranged differently

2)Starter motor on opposite side (compared to Vh45 and most other nissan engines)

3)Bellhousing pattern offset to match different starter location, and dowel pins in different spots. I had to modify my Mazworks adapter plate to work, but easy to do with hand tools (mark and drill new holes, bolt pattern is still identical)

4)Vh41 has a nice cast aluminum oil pan, with a flat bottom, which is great for mockups and storage (not to mention heat transfer!) because it will sit nice and even on a pallet! VH45 had a stamped-steel oil pan. i believe the capacities were identical, but the VH41 definitely wins in this regard.

5)75mm throttle body rather then 90mm (and all came with traction control)

6)Vehicle immobilizer standard on 41's (so either use 45 computer and harness or get Nats turned off by a nissan ecu specialist such as Jim Wolf)

7)Intake manifold VERY different (US market VH41 only)

8)VTC solenoids screw into cyl. heads on 41's, like RB25's setup

9)Power steering pump on opposite side (from VH45)

10) No ignitor chips on VH41, power transistor is part of each coil pack

11)Different water pump pulley to suit different belt drive arrangement

12)Log style Cast iron exhaust manifolds rather than tubular exhaust manifolds. At least the pre cats unbolt from the Vh41 manifold, unlike the tubular manifolds of the VH45. VH41 manifolds are much closer to block.

13)No coil covers on Vh41, coils are happy to be seen.

14)VH41 engine harness has built-in fuel pump relay for all you guys swapping into cars not factory equipped with EFI. Sweet.

 

15) due to more compact accessory arrangements, Vh41 is about 1.5" narrower than Vh45 despite having identical bore, bore spacing and deck height.

 

IMHO the VH41 is the better engine. The rotating assembly is interchangeable, so you can easily up the stroke, and all the other setbacks I'm sure are easily fixed (by porting the heads, etc.) and the accessory mounting just plain makes more sense. (e.g. the VH45's alternator is wedged between the A/C compressor and a hot exhaust manifold. No wonder the alternators go bad on them all the time!)

I'll try to get some pics (since I'm starting a VH 240sx build soon)

once I know where the project is headed. Since so many people are doing this swap now, I think I'm going to have to lean toward a wilder build, involving itb's and turbos.

[OlderThanMe]

One question I have:

Will VH41 timing chain gears work on a VH45 crankshaft?

Or do you have to move VH45 heads, timing chains, and other tensioning parts over to a VH41 block?

 

I have a VH45 that I disassembled so I have seen how it all goes together and I believe that the VH41 block is superior just for packaging reasons.

 

Also it would be nice if a stock VH45 tranny could be modified to fit the VH41 block as I have a perfectly good 120,000 mile VH45 4 speed. (I.E. cut/weld bellhousing to clear the starter)