Honda V8R1600

[Gollum]

Ok, so I took quite a bit of flack at the most recent BBQ that I (really stressing that I there) put on. I've been toying around with an idea, not like I'm REALLY going to do it this week, year, or decade, but as a possible project. I'm addicted to figuring things out and sometimes need a break from trying to figure out my woman, so engines are a good cool down.

 

 

So here's the scenario, take two Honda VFR800 02'+ engines, and mate them together to creating a flat plane crank V8.

 

Why?

 

1. Sound. Flat plane sound rules all. Some might not agree, but this is subjective and I'm allowed my opinion.

 

2. Lightweight HP. This combo would be well under 400 pounds for both engines AND transmissions. 360 pounds is my estimated wet engine weight.

 

3. Uniqueness. A Z that makes THAT sound will turn heads, and keep people staring for quite a while on the work done.

 

4. Cost. I'm predicting the cost of this engine setup to be well under HALF what ANY other person will spend making a flat plane V8 out of anything commonly available. IF you can get a crank made for under 2k you'll still be spending money on a custom crank, and in order to make up even HALF the difference between most motor's redline and this motor's redline will cost big time. Let's not forget you'll most likely need different pistons and rods to match with that crank....

 

Why NOT to do this:

 

1. Not a ton of power. Without force induction we're looking at around 200 crank HP if things go well. Without rebuilding the engine for force induction the limitations will be around 400 crank HP, which is plenty imo.

 

2. Time consuming. So what... if I have another drivable Z I won't care how long it takes. The longer the better imo.

 

3. Fabrication work. If this is a problem for you, why are you on hybridZ???

 

4. Silly engine/displacement/etc. If this is really an arguing point for some of you, get a life. Some people think a SBC in a Z is silly, and TOO MUCH displacement for the car.......... WOW....

 

 

 

Ok, onto the good stuff.

 

Backround on the engine:

 

The VFR is a 90 degree V4 engine 782 cc with bore/stroke of 72/48 mm. It's liquid cooled, oil lubricated (wet sump) and has a block intergrated ultra close ratio 6 speed transmission.

 

Shifting is sequential, and clutch is hydraulic operated. Clutch is a multiplate wet setup.

 

Crankshaft has two journal locations, had the engine has a firing pattern of:

(degrees noted are degrees between cylinder fires)

1 - 180degrees - 3 - 270degrees 2 - 180degrees - 4 - 90degrees - 1

 

Stock compression ratio is 11.6:1

 

EFI is Honda PGM-FI

 

Engine uses an electric starter

 

 

Onto the meat:

 

Now, as for the timing in a dual engine setup. You can't get a balanced Ferrari firing pattern without just a tid bit of work, but it's not much really. If you stack the motors together, to resemble a V8, you'll have a front and a rear engine yes? Take the rear engine's left bank, and advance/retard the camshaft 180 degrees. Then rotate the crankshaft 180 degrees backwards, or 540 degrees forward. This WILL give you a Ferrari firing pattern. There's actually a couple different ways you could configure these engines and still get a perfect LRLRLRLR firing patter (left bank, right bank).

 

 

I'd originally considered converting to a convenstional RWD transmission, but the reality of getting a close enough ratio transmission to USE the 11,750 redline of the engine and still drop gears above vtec is just plain EXPENSIVE. I'd have to be going with a custom ultra close ratio transmission, which would end up costing more than the engines, easily.

 

So I started the work of pairing the transmissions (in my head). I'd thought that it made the most sense, since the primary shaft of the transmission protruded out both sides of the block, to have the shaft machined to accept a slip yoke shaft since the output was a toothed gear just like any other transmission. The only difference is that it's taken up with gears for the sprockets, instead of mated to a driveshaft.

 

But.... I think I found something cheaper, easier, and all around makes a bit more sense. Using Chains.

 

Using a chain would allow me to use a 100% stock motor with no modifications other than machining the coupler for the crankshafts.

 

To explain how I'd do this I first need to explain the mount setup. I plan on running a full cradle, not on the engine side of the mount bushing, but on the engine side of the mount bushing. This will allow me to SECURE the timing of the engines together and make sure the engines don't move separately. The cradle would have two bars/beams, one on each side, with a connection piece going between the engines to give more rigidity to the cradle.

 

So off the cradle, I'd put a shaft mounted on the transmission side of the engine, hung on high speed bearings that can take the maintained high speed loading of an engine. On this shaft would be three sprockets. One for each transmission output sprocket, and one in the middle, between the engines going towards a lower hung bar on bearings just under the oil filter of both engines. The secondary bar will sit on the side opposite to the transmission, and both bars will be securely mounted to the cradle, so the slack can't adjust with engine movement. Obviously adjustable sliders on the mounts would be a necessity to allow for chain installation and expansion adjustment.

 

The reasoning for moving the energy to the lower shaft would be to get the output closer to the center of the engine, to allow the engine to sit close to the center of the engine bay without the driveshaft aiming way out to the side. This lower secondary shaft would have the output for the driveshaft, and could even be machined to fit the OEM nissan yoke, to make for a 100% stock install, if that's what I wanted. Ideally an aluminum shaft would be in order, as with this low torque engine, every pound saved in rotating mass would be worth it.

 

 

So that's about where I'm at. If I where to do this for real though, I kinda already have the rest of the Z build rough drafted on paper.

 

Goal weight would be 1600 no gas, no driver. That might seem impossible, but i think it is. This wouldn't be a street driver (though I plan on it being registered), so it won't have luxuries.

 

I'd probably run a smaller fuel cell, somewhere around 10 gal.

 

R180 3.364. I'd convert a subie CLSD R180 if I can. I think there's a year with the same spline count (27 right?)

 

No side windows most likely. Door skins only, race cage. Rear glass would be lexan.

 

Whole front would be composite. I's really like to make a one piece front end that pivots forward, like a triumph spitfire or daytona coupe, and tube frame the front maybe.

 

Brake rotors would be kept relatively small, as I would plan on running a 15" rim max, 14" if I can make it work.

 

Might consider a 225 wide tire, but would most likely stick with a good 205.

 

Might consider the subie rack conversion.

 

 

I figure with even a 1800 pound Z, and 150+ real rear HP, and 205 wide tires, the thing will move pretty good. And the sound.... Oh gawd.

 

I also doubt that I would leave it NA for very long. I'd want to start out NA and get it proven working and on the road/track, but in the end it would get two turbos. I'd even build the first headers to accept turbos, and make a J-pipe to mid-pipe setup, so that once I added turbos I just make a new J-pipe. If that were to happen I'd be shooting for around 300-320 wheel HP, which should be attainable with custom EFI programming and ethanol.

 

 

So yea... it's a work in progress. I've got a thread going on a VFR board, those guys are awesome and have already been a big help. SOOO much better than OTHER honda boards...

[NZeder]

If your going to the trouble of doing this - why not make it 3 VFR800 engine = 2.4l V12 now that would be something different in a zed as most install a V12 that is somewhat larger than that and from another car - 3 x VFR800's engines would still be small and light weight too. However I have not idea if this is even possible. But as I have owned 2 x VFR800 and 3 x VFR400 I know why you would want to use two of these engines I just love those honda V4's.

[auxilary]

Oh yeah, you guys should've seen him at the BBQ... He was practically touching himself all over much to my, ecc's, drummingpariah's disgust

[Drax240z]

3 wouldn't be much more work than 2 either... 2.4L V12 sounds like a hell of a cool concept to me! It'd still truly be a 240z!

[Gollum]

A flat plane V12 would be... interesting to say the least.

 

If I was going to make a multi-engine V12, I'd use the VG motor. Can anyone say VG60ET?

 

Only using two VFR800 engines only gives me 1.559 cc's, but if you think about it, a Honda B16 turbocharged makes PLENTY of HP for a 2,300 pound car and those only rev to 8k.

 

Another factor to consider, is that two of these engines will weigh at LEAST 340 pounds, possibly as much as 400. Putting another in the engine bay adds another 180 pounds or so, and that much farther forward. Generally this isn't that big of a deal in a Z, but I won't have a transmission in the tunnel, which means I'm actually removing a ton of weight from the rear tires.

 

So I agree a V12 idea would be neat, but I just don't see myself doing it. I'd sooner consider running dual inline 4 engines from a bike for an inline 8.