alternate R16 pistons

[Gregs672000]

Maybe not the best place to post this, but I do have three 30 over (yes, 30 over) U20 pistons with very few hours on them available for free if anyone wants them. Unfortunately I broke one when pushing it out... fell out of my hand and broke the skirt, but the other three are perfect.

[Poobah]

PM'd

Steve

[Gregs672000]

They're gone! Wow, that was fast... you snooze you loose around here!

[gmiles]

H30 pistons. Yup, that's right H30 pistons. Same bore, pin diameter, rings, etc. -2 cc dish. $125/set. No need to modify the skirts.

It took a while, but my 5 main R16 block is finally at the machine shop. The shop specializes in custom and industrial engines. The shop is putting H30 pistons in. Using the stock R16 crank and rods and going .020 over on the bore.

Here's the deal: The aluminum head was already cut and is .016 under. The shop will deck the block .002-3 and do the same to the head to clean it up. The head was cc'd and has 42cc chambers. Compression is estimated at about 9:1 with the dished pistons.

Also, I gave them one of the toyota 20R pistons I bought. They said the toyota pistons would work and would be the equivalent of .045 over. They didn't do the math for the compression ratio, but the toyota pistons have a dome. My guess is the toyota pistons will give a slightly lower compression ratio with an uncut stock block/head because the distance from the pin to the edge of the piston is shorter on the toyota piston (would sit further down the bore).

Alternate R16 pistons. There you have it. Nissan forklift H30 pistons work with a decked block and/or a cut head. Toyota 20R pistons will work too (YMMV-Use at your own risk since I didn't have the machine work done to prove it). I wonder if the H30 piston is the same as the mythical VG30 piston?

The shop also said they could build a stroker and could easily get the parts, although they showed me only the H20-2 cranks (not the Type 1). Cranks were about $150. Again YMMV.

L&R Auto in Santa Fe Spring, CA 562-802-0443. Larkin is the shop owner and knows H20's really well. Derrek is his youngest son and knows his stuff, too.

[TJFLY]

Looking through the Carrillo Racing catalog it looks like the pistons are from the VG30DE part #SC7330. The specs are in line with U20 pistons so perfect for a stroker or stock upgrade based on the numbers posted. Know that the kit comes with 6 pistons so it may be a good idea to go in with a couple of people and purchase 2 sets. 2 sets =12 pistons = enough to stroke 3 engines. Hope the info helps.

[Pjackb]

Its not a matter of VG30 pistons being mythical, its knowing which vg30 pistons to use. My guess is that they are the NA first generation version, but I don't know for sure.
Will

If doing the stroker, try to find the VG30 pistons that are mentioned all the time but no part # ever shows up so I tend to think it's imaginary........

Who knows which ones to use Will?

Not mythical just that the folks who know dont seems to share information easily but I am presently having a spare U20 rebuild with 88mm VG30 pistons and custom Manley rods . I had no part numbers either but you guys know me , I did some research and came to the conclusion that's it's either one of these 2 parts numbers from the ACL piston catalogue (specs are identical just locking device is different )

6MKRY8034 - VG30E SOHC V6, 1984-1988, with a 21mm pin diameter and two slight valve cutouts in the crown
6MKRY8035 - VG30I SOHC V6, 1990-1997, with a 21mm pin diameter and two slight valve cutouts in the crown
http://mitsubishilinks.com/fsm/acl_pist ... s_pp99.pdf





Hope this helps

[JT68]

We set up a couple short blocks with VG pistons and the benefit really isn't worth the hassle. You really won't save any time or money with VG pistons since almost everything about them is wrong. The stock rods don't fit under the piston without modification and the pin height is wrong for the U20 rod. So you end up having to make or buy custom rods and/or do a bunch of extra machine work to make them fit. It's a bit of a kludge for really very minimal benefit.

By the time you do all that silliness, you can buy a much, much higher quality piston with or without a dome for the U/H/R-engine.

The size selection is also very limited with VG pistons. (stock bore is undersized for roadster). After you build quite a few engines, you realize using parts properly designed for the engine is a better plan. Way less hassle, way better parts.

[Mochi]

i dont know if this helps but lou mondello was selling a h20 crank, vg pistons, and what looks like his own rods. maybe if you really wanted too you could contact him and see if you could source his rods to make it work

[Curtis]

Um, did you read Steve's 1840cc stroker thread?

[JT68]

The R18 3-main stroker has special piston/rod requirements that is not the same as the R16 or U/H20 because it is an engine Nissan didn't build. The pistons cannot be the same height as EITHER R or U unless one makes a custom rod. (Shorter than R, Longer than U)
The common method for that build is use stock 1600 rods and make a custom piston. (toyota or custom forged etc.)

Alternatively one could use standard dimension roadster pistons (either domed or flat) and have custom rods made. The elegant way to do this is lightweight forged pistons and custom forged rods. The lightweight components help the engine live since 3-main (and all R & H20 cranks) have rod oiling issues.

[SLOroadster]

We set up a couple short blocks with VG pistons and the benefit really isn't worth the hassle. You really won't save any time or money with VG pistons since almost everything about them is wrong. The stock rods don't fit under the piston without modification and the pin height is wrong for the U20 rod. So you end up having to make or buy custom rods and/or do a bunch of extra machine work to make them fit. It's a bit of a kludge for really very minimal benefit.

By the time you do all that silliness, you can buy a much, much higher quality piston with or without a dome for the U/H/R-engine.

The size selection is also very limited with VG pistons. (stock bore is undersized for roadster). After you build quite a few engines, you realize using parts properly designed for the engine is a better plan. Way less hassle, way better parts.

The VG or KA pistons are for a Long Rod U20, not standard U20 rods.

They are a terrible idea if you are trying to use U20 rods for all the reasons you state. In long rod use, its my understanding that there are decent gains in both HP and torque to be found.

Will

[Daryl Smith]

" The lightweight components help the engine live since 3-main (and all R & H20 cranks) have rod oiling issues."

Lighter wieght pistons and rods help in a number of ways:
1) quicker acceleration - (lighter weight is easier to move) Piston for reciprocating weight, Rods for both reciprocating and rotating.
2) Smoother running - with a lighter piston (less so for the rod) there is less inertial forces at the top and bottom of the stroke (less vibration).
3) Increased reliability - the lower inertial forces decrease stress on the crank and bearings.

A longer rod allows for a shorter and lighter piston, lighter than possible with a shorter rod.
At the extreme end the R/H/U geometry in stock 83mm stroke form will allow for a 6.2 inch (157.48 mm) rod and 28 mm piston pin height, and very significant weight savings (near 700 grams or more per cylinder!). I have read that just a 200 gram reduction is VERY noticeable.
If you have the opportunity to drop some weight from engine parts, especially from the piston, I would reccomend you go for it.

Oh....if you intend to really push your R/H engine, have that oiling issue looked after!

[redroadster]

You needed the 98 octane gas to run those 12 to ones
That you can't get close to now , I'd opt for the lower compr.

[Cyclewrks]

High octane gas is easy to get, at least in my area, there are multiple stations with pumps selling pure (no ethanol) 98 and 110 octane fuel.

[redroadster]

High octane gas is easy to get, at least in my area, there are multiple stations with pumps selling pure (no ethanol) 98 and 110 octane fuel.

I can't imagine what 110 octane would be for ?
And would be probably leaded AV gas
It's $6 a gal in Cal now and it's said that's coming to the rest of US