Comparison between VH45, US VH41, and JDM VH41 heads... many pics!

[Mettler]

So while I was in Palmy, Nyloc and I paid a visit to Brian Hartley's head workshop. Nissan V8s galore, it was excellent!

Brian's a very accomodating gentleman and takes the time to explain things properly. He allowed us to grab a few heads and compare differences.

So Nyloc & I spent some time comparing ports, valvetrains etc, between an early VH45 head, US VH41 head, and JDM VH41 head... and taking careful pics of them.

This is what we found:

Label on a JDM spec VH41 head. This confirms them to have the sodium valves:

The same JDM VH41 head:

Assorted heads lying around:

Scale reference photo:

NZ $2 coin inside the intake port on a US VH41 head:

This is how we deduced this head to be a US VH41 head, because the manifold mounting face was at more of a vertical angle than the other two heads, so was obviously for the log type manifold:

VH45 head & US VH41 head. Same cylinder bank, same way up. Notice additional casting on the VH41 head, as opposed to the VH45 with which the cover takes up that area.

Same as above:

Identical valvetrains in both heads, except it appears the US VH41 has some additional webbing between the center spark plug holes and to the left of the left one. Also, the US VH41 camshafts don't appear to be capped at the ends like on the VH45:

Port comparison between VH45 and US VH41 heads:

Same as above but I'm holding the JDM spec VH41 head above the other two, note on the JDM VH41 head the cams are capped at the ends, just like the VH45, and also have the additional webbing between spark plug holes in a couple of places:

JDM VH41, US VH41, VH45... note identical combustion chambers & valves:

US VH41 combustion chamber:

VH45 combustion chamber:

JDM VH41 combustion chamber:

Misc:

A used and abused VH combustion chamber from a motor that experienced severe failure, probably due to overrevving:

Probably due to this:

Some further pics from the damaged head:

Note how little porting is actually required to achieve the 550hp or so that these motors produce, they're obviously just built for huge revs:

Misc photos taken around the shop:
Modified by Mettler at 8:21 PM 2/11/2007

[Ezekial]

Very nice photo's mate!!!!

What dished pistons are in the bin?

[Mettler]

I don't know, Brian deals with a variety of engines including chev, holden, ford, toyota etc... could be for anything!

[SuperHatch]

It would be interesting to compare the US 45 Oval ports to the JDM 41 ports. I think we'd find that they're nearly identical. I know that my 94 motors ports look nothing like the US 41 ports.

[maxnix]

Uhhh...could I have those VH41DE headers he is discarding?

Cooling pasages look quite different on the 45 block at the back cylinder.

Thanks for posting your pictures. I think this requires furthere investigation.

[Nyloc]

It would be interesting to compare the US 45 Oval ports to the JDM 41 ports. I think we'd find that they're nearly identical. I know that my 94 motors ports look nothing like the US 41 ports.

That would sound logical.

Its interesting to see the VH41 (JDM) and VH45 (US) were produced at the same time by the same company and yet are so different, in port shapes, timing chain layout and even the completely different castings for heads and blocks, but with the same basic dimensions. Even the inlet manifold is the same shape, yet different casting. Anyone know why the produced 2 different engines at the same time, admittedly different capacities, yet the crank and pistons interchange anyway? Is one a close relation to the 3.5 race motor, the other only loosely related?

[Q45tech]

Since Japan displacement tax group is 4001cc to 4500cc................4494cc Q45.

I've always wondered why a 4.1 engine in the first place. [Just to beat Toyota?]Obvious why Lexus was 3998cc to avoid extra $310US equivalent annual and $2,000 at purchase surcharge.

[elwesso]

Very interesting.... maybe im being dense, but I dont really see a whole lot of differnece that would make me prefer 45 or 41 heads.

Are the US 41 heads identical to the JDM 41?

What about those cams...???

[Mettler]

Very interesting.... maybe im being dense, but I dont really see a whole lot of differnece that would make me prefer 45 or 41 heads.

Are the US 41 heads identical to the JDM 41?

What about those cams...???

No, they aren't at all... you should carefully go through my first post again, there are a number of differences which I comment on with each pic. The ports are bigger on the JDM VH41 heads, they are at a better angle to the back of the valves, and the camshafts are capped at the ends like on the VH45 heads. The JDM VH41 heads are better than US VH41 heads.

I can't think of much that makes me prefer the JDM VH41 heads to the VH45 ones... though I think they could be considered application specific... larger area oval ports being favourable to higher RPM operation (suits the shorter stroke/higher revs of the VH41 motor), and the slightly smaller siamese ports being more favourable to high air speed at lower RPMs (suits the character of the longer stroke VH45).

These differences aren't unlike the difference between 2V and 4V heads for Ford 302/351 Cleveland engines. One's a small port, one's a big port. Port size determining where in the rev range the air speed is ideal for the best CFM & fuel atomisation etc, but the Nissan V8s will be a lot more closely matched in this regard, as the two different head types make a huge difference for these Ford V8s.

Regarding the cams, I spoke to Brian about it and he's going to get a cam spec sheet for me. I'm giving him time to do this because he's such a busy person that I wouldn't want to get on his nerves. He's looking for a VH45 at the moment, from which to take the internals and put into my motor.

[defrag010]

Awesome pics! did you get any pictutres of his machines? Also, that H-beam rod in the messed up pic was probably a custom made one, eh.

[elwesso]

sounds good...

I think i had a brain fart about the US 41 vs JDM 41 heads....

remember the later 94 45 heads had the oval ports... I wonder if that would make them nearly identical to the 41?

[SuperHatch]

remember the later 94 45 heads had the oval ports... I wonder if that would make them nearly identical to the 41?

I asked hat already... judging from the looks of them my US 94 heads look just like the JDM 41 heads.

[Mettler]

Awesome pics! did you get any pictutres of his machines? Also, that H-beam rod in the messed up pic was probably a custom made one, eh.

Nah sorry man I posted up all the best pics we took. He had a huge boring machine, some valve seat machines etc... not really sure, because I don't know much about machining & head work I didn't pay much attention to his actual equipment... but I do remember seeing at least 4-5 main machines that would be frequently used, then he had rooms off to the side with more stuff in them (flowbench, engine dyno etc). I do remember seeing a big rack of different boring, honing, dremel & other bits tho.

We neglected to photograph a VH41 on a stand in one of the side rooms under a cover, which had a massive alloy plate built in to a wicked custom sump setup... dammit! The plate was there to bolt the external oil pumps to etc.

I think i had a brain fart about the US 41 vs JDM 41 heads....

remember the later 94 45 heads had the oval ports... I wonder if that would make them nearly identical to the 41?

Eheh... yeah if the VH45 oval ports are the same dimensions, then the heads would flow more or less identically. The only real differences are in the casting of the heads with regard to the front covers etc.

One myth I think we've successfully laid to rest is the one where people think the VH45 is physically larger than the VH41, it isn't. They're exactly the same size, it's just an optical illusion caused by the wider front covers on the 45, and the VTC solenoids being on the front of the intake cams rather than feeding in through the side of the heads like on the VH41.

Another myth laid to rest is that of VH41s apparently not having VTC... they do. As you can see in the pics, the little hexagonal shaped bit screwed into the side of the JDM VH41 head at the front is in fact a VTC solenoid valve. Also note that the US VH41 head has the tapped hole for VTC solenoids too. The oil feed for the VTC drums on the ends of the intake cams are obviously just relocated.

[TT2by2]

Thanks for the photos. I was wondering if you saw any assembled VH41s. I was wondering if the US VH41 and the JDM VH41 shared the same accessories and belts. I live in the US and would prefer the JDM VH41 but if they didn't share the same alternator, water pump, power steering pump, A/C compressor and belt sizes as the US VH41, I think I will just go with the VH45.

[Mettler]

Just a guess but I think they do share many of the same accessory systems on the front of the motor, as I referred to the Y33 FSM for the water pump instructions and that features the US VH41.

Use my project car pics for comparison if you need to, I took dozens of pics of my engine (JDM VH41).

[TT2by2]

Thanks

[elwesso]

i think most people give clearance benefits to the VH41 due to the different style exhaust manifolds on the US 41s (the log style)........

[defrag010]

What kind of dizzy is on the VH with blue valve coves?

[T45]

That looks like a Mallory driven off the cam. That's an awesome idea and design.

[TT2by2]

Another question crossed my mind. Do you think it would be possible to use the VH41's alternator bracket to relocate the side mounted alternator of the VH45 to the same center mount position as the VH41?

[Mettler]

No because the VH45 alternator is a mirrored design of the VH41 alternator. VH41 alternator is proprietary. I looked into this when I fried a couple of my alts. Also the block is a physically different casting, I don't think things bolt together in the same places on the two motors.

[TT2by2]

Thanks again

[gdz1la]

metter im looking at buying a VH41 056728,and arround 1993is this the good ported model its from japan and is in auckland. is it ok to boost it to 700hp std?

[Mettler]

Yeah, just check what colour the TCS motor is... it should either be black or bronze in colour. I think all the jap spec VH41s are more or less the same with some minor external differences in colour here and there. All have the oval ports & dual row timing chains.

It should be safe to 700HP with mint tuning and really good cooling. The internals can handle it, how many SRs and RBs have we seen making up to 500HP & 900HP respectively? (RIPS made that white R33 GTR from the UK put out like 900HP on stock bottom end)... and 350HP is nothing for a stock SR (which actually has smaller rods & pistons than a VH.)

At 700HP however, I'd be concerned with cooling the heads effectively. The block & heads have quite large coolant passages between them, the headgaskets however, largely cover these big coolant passages, reducing the size to about 4mm holes through which the coolant can pass. I'd do some research & talk to a few pros as to whether opening these out a little bit would be beneficial or not. Heads & headgaskets won't last long if you overheat an alloy engine, which I'm sure you know.

[marksport]

Hey Mettler, the rod pictured above looks like one from Eagle Specialty. Can you confirm that it is or tell us what it was originally made for and what kind of modifications was needed to run that rod in the VH?

[ScottJackson]

What is used to make that carb intake? It looks to be two halves welded together in the middle. With gas as expensive as it is, I'm seriously considering using my extra VH45 in my '69 mustang (although the 514 big block is all assembled right now).

[Mettler]

Hey Mettler, the rod pictured above looks like one from Eagle Specialty. Can you confirm that it is or tell us what it was originally made for and what kind of modifications was needed to run that rod in the VH?

Sorry man if I knew that I'd have already posted it on Nico. Engine builders don't give away information like that, I'm sure Brian would prefer if people bought parts through him so he can make a dollar.

[marksport]

Sorry man if I knew that I'd have already posted it on Nico. Engine builders don't give away information like that, I'm sure Brian would prefer if people bought parts through him so he can make a dollar.

In that case, can you ask him as I spoke directly to Eagle and they do not make a rod for the VH45. His may be cheaper than getting custom rods from some of the manufactures I have gotten quotes from.

[T45]

TTT

[tmorgan4]

After seeing this thread for the very first time...awesome pictures Mettler! Looks like Nissan V8s are a lot more popular where you're at than here in the US.

A couple questions come to mind....

Why are these guys with highly modified VHs swapping out the ignition coils+fuel injection setup for a distributor and a carb?

I'm 99% sure my 92 VH45 didn't have that little warning about Sodium filled exhaust valves....Does anyone's VH45 (that came with Sodium filled valves) have this?