Aythya

I recently ran across a post on the XOC about building a VG34. Using Infinti pistons different crank, boring .60 over; basically stroking a vg33 engine. Has anyone else read this post or anything similiar? I have done so on a Harley Davidson using Harley parts but never mixing-I know that Infiniti is Nissan but do not know how to come up with comparable numbers etc.

The post claimed near 300 horses on pump gas and a reliable engine. Any thoughts as I have already seen several good candidates in the graveyard waiting for someone to bring the block back to my house.......

thanks in advance!!

OffroadX

"VGs are very much like L-series in that you can mix and match lots of parts. ALL North American VGs have the same stroke and they all have the same size bearing journals. I do not know about the VG20 found overseas. The VG30E block cannot be bored to use VG33 pistons, the cylinder walls are too thin. The magic formula to build a VG34 is this: Bore a VG33 block .060 over. Use *stock* 1995 Infiniti Q45 pistons, rings, and wrist pins. Use VG30ET rods with custom, larger I.D. small end bushings as the Q45 wrist pins are 1mm larger. You can use any SOHC VG crank (they are ALL cast), but there are differances in front snouts and related accessories so use one you've got all the parts for. Avoid any SOHC VG crank that's been run with a serpentine accesory belt as these tend to break off the crank snout! The above VG34 combination is the one used in the off road trucks. If I remember right this bottom end comes out to 10.5:1 compression, perfect for a street motor. Sly said a VG34 with "good" cams and stock heads will make 250hp on 93 octane in street-trim. With port work and the "right" cams and intake a VG34 can make 300hp on pump gas. Sly says that no matter what you do they won't make power over 6500rpm as the displacement is too big for the head design. The question I've never heard answered is what happens when you turbo a VG34? I don't know anyone that's done it so I don't know what the limit is. I'm guessing the crank will come apart first. I've been told by many that SOHC VG cranks are short lived when 350hp is exceeded. It is possible to use the forged DOHC crank in a SOHC block but it requires a custom flywheel and messing around with a few things to make it go together. It's relatively painless but I've only done one so far. If you are thinking about building any VG be warned that they are difficult and expensive just to rebuild stock. Many automotive machine shops cannot hold the tolerances neccesary to make a VG live, especially if it's warmed-over. Rebuild parts are also expensive, but then they should last 200k miles."

Sounds like a lot of work for overkill if you ask me.
I doubt the auto tranny could take that kind of power, though the manual probably could since it's essentially the same one used behind the 300ZX TT.

Brent

ScottG

I'd be interested in more information on something like this. I bet it's possible. I've heard about guys rebuilding Honda Civics with Accura parts. It's not something I'm smart enough to do. Someone would have to do it first and put together a kit

One problem I think you would run into, is the stock computor would have to be reprogrammed to run the modified engine.

Have you heard of any specific weaknesses with the auto tranny? I read a post one time in which somebody said something like "Everyone knows Nissan auto transmissions are known for being weak." However, I have never seen a single complaint about the Xterra's auto transmission on the message boards I follow. I don't know whether it would hold up to 300 hp. The manual might, but something would probably have done about the clutch. I've seen several posts regarding smoked clutches.

Aythya

Thanks guys for your input. I don't know enough about Nissan engines, despite this being the second one Ive owned, to do what I'm asking about. After all they don't make things as simple as Chevy and Harley. I don't want or need to push 300 horses either. But 200+ would be really nice in that truck. And as I mentioned Ive seen several good graveyard candidates to get the parts mentioned in that post. This is really one of the best places I know to talk tech as not many people around here are jazzing up Xs.

Also, since Im not rock crawling like you guys I don't need as much lift so I can spend money in other places.......

Off road, what makes you think the Auto tranny won't hold up?

Thanks again for the replies!

OffroadX

From what I've gathered the AT just isn't up to high output. Supposedly that's part of the reason the supercharged VG33 is so mildly tuned over the NA engine, Nissan didn't trust the tranny to take much more.

Brent