Josh's 280Z VG30DE 5-speed swap!

[pureZero]

I have decided to go through with a swap I have been contemplating for a long time. I am documenting the swap on Northwestnissans.com, and I figured I would do the same on here!

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

So... The L28E that came with my car is in pretty poor shape, sort of. Never been machined before, which is good, but the measurements are all over the damn place. I don't have the money to do that (Please don't point out the cost of the swap, I already know... haha). Basically, I have an entire 1990 300ZX just sitting here, and I would really like to use it. I'm a professionally trained auto-tech, I can use a wire-feed fairly well, and since my dad is basically a master machinist, fabrication isn't going to be a huge issue either. I'm planning on picking up an OBX LSD and clean it up, custom aluminum driveshaft, probably a custom shifter assembly, etc...

If anyone feels that they have helpful information on this, feel free to reply!

[pureZero]

So, It's going to get the Z32 5-speed, 80-83 R200 3.900:1 final drive, and 195/60 r15 tires. Also, I'll fit an Autometer electric speedo and tach, and other gauges.

Need to figure out how to compensate for the shifter on the Z32 5-speed being an extra 5.5 inches farther back, and of a different design, as well...

The car will have about 235-240 hp, weigh about 3100lbs (200lbs lighter than my 2+2 z32 was), and I chose that tire size/diff gear set because I'm looking to get as close to the Z32's final drive as possible. The tires should give the final drive gear reduction enough of a boost to allow for a little better acceleration than the N/A 300zx, but also be geared high enough to keep the fuel economy close to what the L28E L-Jetronic FI has.

The thing won't be a race car, but it won't be horrible either. Plus, I will be able to swap a VG30DETT directly into the car later on. I'm also keeping the L28 mounts in the car, to be able to swap the original motor back into the car.

[Zed Head]

classiczcars is a great site but this one might fit your project better - HybridZ

[pureZero]

I understand that, I just wanted to let people know what I'm doing on here. Plus, the questions I would need to ask would be ones that people here would be able to answer.

[pureZero]

Also posting about this build on HybridZ.com

[EuroDat]

I'm also keeping the L28 mounts in the car, to be able to swap the original motor back into the car.

Do you mean the mounting points in the chassis? The crossmember and rear engine mount support are removable. These could be modified to suit the V6 without effecting the structure of the car.

Goodluck with your project

Looking forward to seeing some photos.

Chas

[pureZero]

I want to mount the VG as far back in the engine bay as possible. The motor isn't light, and weighs about 200 lbs more than the L28, so the farther back it is mounted, the less it will affect weight distribution.

[pureZero]

Do you mean the mounting points in the chassis? The crossmember and rear engine mount support are removable. These could be modified to suit the V6 without effecting the structure of the car.

Goodluck with your project

Looking forward to seeing some photos.

Chas

If I can add something to them to make it work, then great, but It's still going to be mounted as close to the firewall as possible.

[pureZero]

As far as the exhaust... I will be whipping up a set of 2.25" custom headers using the mating surface off an extra stock set. After that will be 2.25" straight-pipe with twin glass packs. The step down from 2.5" to 2.25" exhaust should actually give the motor a little bit of a performance, since it will keep the exhaust gasses a hotter than the larger size, making it flow faster.

[LeonV]

As far as the exhaust... I will be whipping up a set of 2.25" custom headers using the mating surface off an extra stock set. After that will be 2.25" straight-pipe with twin glass packs. The step down from 2.5" to 2.25" exhaust should actually give the motor a little bit of a performance, since it will keep the exhaust gasses a hotter than the larger size, making it flow faster.

I don't think you have a very solid grasp of exhaust dynamics. FWIW: Exhaust Tube Sizing: I did your Arithmetic for you!! - Exhaust - HybridZ

[pureZero]

I am pretty sure I do... The stock 2.5 inch tubing size can support a little over 1000 hp, as proven by Z1 Motorsports on their widebody Z32. Now... Do I need that big of exhaust? No. The fact of the matter is this... What do motorcycles have done to their exhaust to improve performance? Low-restriction, high flowing exhaust. Now, that doesn't mean that a larger size is put onto the bike. There are times that a smaller tubing size is preferred. Tubing size actually has a huge effect on how well exhaust gasses flow. Too small, and there isn't enough space. Too large, and the gasses cool off too much to flow well.

A higher flow capacity doesn't equate to better flow. Actually, it can be quite the opposite. Yes, if one were to take, say, a V8, and build it for max output, a larger exhaust will most likely be needed. But does that mean that stock exhaust size is the lowest you want to go? With the VG30DE, a smaller size exhaust, with very little restriction, is more than capable of supporting the motor's output. It could actually improve the performance, because the exhaust gasses may be able to flow better. Without any real restrictions, the 2.25" exhaust should, at the very least, flow just as well. The correlation between flow capacity and actual flow only exists when the engine's pumping capacity is taken into account. Theory is great, but it needs to work in the real world, or it's just theory.

Lastly, remember that I'm not working with a turbo motor. Yes, larger exhaust after the turbine can help it spool better, but it's the complete opposite when working with natural aspiration.

Edited June 25, 2013 by pureZero

[Zed Head]

I think that LeonV might be just disagreeing with your premise that restricting flow "should actually give the motor a little bit of a performance". That's been shown to be an urban legend, wive's tale, myth, etc. when referring to primary size for headers.

You might be confusing your turbo principles with NA principles. You want hot gases in to the turbo so that they can do work on the turbine. With NA you want cool gases so that they take up less space and get out faster.

Your vocabulary seems to be outpacing your knowledge. Actually doing something is the best way to learn.