VH45 VK45 piston and rod comparison

[marksport]

I have taken apart my project motor and have done the comparison of the VH45 and the VK45 Rods and pistons.



The piston on the left is the VK45, on the right is the VH45. VK45 has shorter skirts and the distance between the rings on the VK45 is less. There is more distance from the oil ring to the pin.



The rods are very similar. You can kind of see the VH45 rod around the VK45 part sitting on top of it.The stem of the VH45 rod is just over 22mm thick vs the VK45 rod at just under 20mm, a difference of over 2mm. The radius of the rod where the stem and the big end meet is also wider on the VH45. The thickness, pin diameter and big end diameter is the same.



The VK45 rings on the left, VH45 on the right.VH45 rings are thicker and wider.

Overall, the VH45 is a stronger motor. Is it superior? I don't think I'd go that far, but booth motors are fairly similar in design and quite capable.

Modified by marksport at 8:03 AM 7/31/2007
Modified by marksport at 8:06 AM 7/31/2007

[konatown]

Great work, sleuth.

Interesting to see that VH really is the stronger internal motor, not just the block.

Wes, I hope you post on the G45 thread a link to this.

[Mettler]

Can someone please fix that first post so the pics aren't displayed five times each too :p

I'd be pretty happy to conclude that the VH45 is a better motor to be honest. I don't see any way that the VK could have improved on the head & port design, and the internals & block of the VH being so much stronger indicates a higher design pedigree.

[SSDwellah]

If you look very closely it seems as if they are different pics - at least the filenames are different and the lighting seems to vary ever so slightly. But I agree it's not like they are different angles or something so the fact that there are 5 of them is redundant.

[sijoko]

There is a big difference in the ring lands between the pistons. The VH piston is definitely more boost friendly. Also, the rods in the VK look like the ones in the Toyota V8s. Maybe, I'm just too old school and put too much emphasis on overbuilding the engine for durability. I guess that a cheap upgrade for the VK would be to use the rods from the VH.

Now, if you change out the rods and pistons for aftermarket forgies, the VK is a great engine. Well, except for the fact that it has smaller valves and needs the valve clearances adjusted over time. One other thing, does the VK have the ladder frame connecting the bearing caps?

[Mettler]

Hmmm, it gets referred to as a main bearing beam in that "Once around the block" article.

[marksport]

Ok, fixed the picture, I was lazy and didn't know that changing the file name didn't work. I don't think I would be able to run a VH45 in the F50 chassis as the emission standards might not pass during smog testing.

[sijoko]

Ok, fixed the picture, I was lazy and didn't know that changing the file name didn't work. I don't think I would be able to run a VH45 in the F50 chassis as the emission standards might not pass during smog testing.

I don't know if it is worth the trouble since a lot of external things are going to be different between the VK and VH. It would be easier to just build up the VK with aftermarket rods and pistons. You could also use the VH rods to save some cash.

[marksport]

The #5 rod bearings from the VK that I took apart, this all that was left....



The #6 beside it had some damage but didn't do anything to the crank where as the #5 did a little. I haven't taken apart the other rods yet.

[sijoko]

Wow, that bearing is ate up. So, what exactly was the cause of failure? Detonation? What did the pistons look like?

[marksport]

Piston and rod that went with this bearing is the one pictured at the top. The owner had a plugged cat which caused his head to warp. He had a shop do a head job, and I think that they may not have drained the coolant properly as there was a milky residue on the bottom of the oil pan. He drove the car for a few days before it started to make noise.

[Q45tech]

Some day I'll examine the bearings in my VH with 315k.

If you still have the pieces handy, why not weigh the rods, wrist pins, individual rings and pistons so we can see/calculate the rotational forces and their differences.

[elwesso]

I will examine the pics better when i get home tomorrow morning

Anyway, I bet more differences lie in the block and crank than in the pistons and heads. I bet the heads, pistons and rods are very similar but the block is much different. Do you have a crank?

[marksport]

I will examine the pics better when i get home tomorrow morning

Anyway, I bet more differences lie in the block and crank than in the pistons and heads. I bet the heads, pistons and rods are very similar but the block is much different. Do you have a crank?

Haven't taken the crank or the remaining 6 rods/pistons out yet. Crank may be micropolished. If not, I will use the crank out of my car.

[elwesso]

I wonder if that extra space has anything to do with the oil consumption issues the VK's have?

[Jesda]

I broke the gallery during an upgrade, but dont worry I saved all the pictures. Its coming back soon.

EDIT: Pictures moved here for now:http://www.q45.org/uploads/VK45%20block/
Modified by Jesda at 6:04 AM 8/4/2007

[szh]

Hmmm ... we can't tell which picture is which in the original post though, right?

Do you want me to fix the original post to point to this new location for the pics, Jesda, or do you plan to put them somewhere else later (so I should wait for now)?

Z

[marksport]

Hmmm ... we can't tell which picture is which in the original post though, right?

Do you want me to fix the original post to point to this new location for the pics, Jesda, or do you plan to put them somewhere else later (so I should wait for now)?

Z

Nope, pics are good with the corresponding description below them. Simply put, the smaller rods pistons and rings are the VK45 parts.