VTEC-E in custom built car....

[rkcarguy]

My first post here...
First a little about my background...
Formerly a machinist and fabricator
Owned/operated a japanese engine import business for 6 years
Now in construction management after a back injury

My first Civic came to me in 2000, a 1988 DX sedan. Importing engines it lasted about a month before a dohc vtec swap found it's way swapped in. I was surprised to see not only more power, but still got about 32mpg on the freeway.
Over the years I owned several different civic's, and picked up a 95cx hatch with the 8-valve econo-engine in it. I was surprised that even with the engines sad shape(previous woman that owned it didn't change oil for over 9K miles and it was smoking+lots of valve noise) we still got 43mpg on a vacation traveling around the state before I replaced it with swap and sold the car.
While importing engines, I had recieved a couple of D15B's that were very strange, an 96+ series engine with what looked like a pair of VTEC solenoids...
After some research I found out that this was a 3-stage VTEC, an enginer offered only in Japanese and European markets for a 2 year span.
This engine not only includes the same features as the VTEC-E, but add's a 2nd solenoid and yet another set of cam lobes offering 130PS above 6000RPM.
I stashed 2 of these in my garage when I sold my business waiting for big gas prices to come. They did.
Just when I was getting ready to pull the current B20B from my Civic and swap one of these in, the market flopped and gas was under $2 again...

We are now on "probation", as the only reason we have cheap fuel is because of the recession. Prices will come back maybe even worse than before.
One 3-stage VTEC I have already stripped down to just the basic package as my car has no A/C or P/S, and installed a 8lb fidanza flywheel and stainless header.

I've tried to talk myself out of it several times but I can't, being a former fabricator and having built several trailers, tube frames, alum boats and tons of other parts, I want to build a completely custom aluminum 2 seat sports car with a rear engine configured 3-stage VTEC engine.
Molds could then be taken off of the completed alum bodywork for duplication in fiberglass or other composites which are both beyond my skill level.
Some basic sketches and measuring of components are suggesting a vehicle approx 5' wide 40" tall and 12-13' long. The rear engine will allow the nose to taper far sooner and should yield superior aerodynamics. I'd expect it to be under 1500#s with some careful weight reduction and parts selection.
I don't see 80+ mpg being a problem seeing others that have attained these numbers with modified Civic's, plus you'd have the power/weight ratio of a mustang GT if you wanted to "play".
The type of shape I'm planning on would be something similar to the blue or yellow car seen in this link at the bottom of the page...

Avion - Would you believe 88.2 mpg?

Any insight, ideas, telling me I'm insane, etc, would be welcomed....
Mechanically it will go really quick, but the body is going to be a PITA.

[SVOboy]

You're right, the body will be a pain, but it should be a good set up. The engine is not as efficient as its predecessor the d15z1, but should still turn in some good numbers.

[Tango Charlie]

You're not insane. And you're not alone. Keep reading threads and you'll find lots of info and like-minded souls. Welcome!

[rkcarguy]

Originally Posted by SVOboy

You're right, the body will be a pain, but it should be a good set up. The engine is not as efficient as its predecessor the d15z1, but should still turn in some good numbers.

The nice thing is I will be running OBD-1 for it's chipping/tuning capability, and I'm planning on designing the engine bay such that anything that fit in the 92-00 civic will fit in this, and that will leave things pretty much wide open. I've also got a D13B that came in the 1996 Civic EL in Japan, a 1.3L D-series engine. If I was looking for a little more economy I could always do a head swap onto this bottom end...
Being a gearhead, I couldn't help hoarding half a dozen oddball engines when I sold my import business after my back injury
This all started when I simply set out to replace my Civic with something newer, and found only heavier, slower, expensive, and worse mpg than my 15y/o sedan...

Why would the Z1 be more efficient? Maybe it has roller rockers and the 3-stage doesn't? I don't remember..

[Christ]

It's not really the Z1 that's more efficient, it's the lean-burn capability that the Z1 has... That, and the upped compression and enhanced combustion characteristics that come from the combustion chambers' quench pads on either side... the Z1's head is the same casting as the Y8 head.

If you could use the lean-burn capability w/ any other Honda engine, especially ones designed to be more efficient than the Z1 california model (which doesn't have lean-burn), it would obviously win.

[SVOboy]

Originally Posted by Christ

It's not really the Z1 that's more efficient, it's the lean-burn capability that the Z1 has... That, and the upped compression and enhanced combustion characteristics that come from the combustion chambers' quench pads on either side... the Z1's head is the same casting as the Y8 head.

If you could use the lean-burn capability w/ any other Honda engine, especially ones designed to be more efficient than the Z1 california model (which doesn't have lean-burn), it would obviously win.

Yep, this is true. As well as the way that the intake is tuned.

[Christ]

I'm not aware of changes to the intake, but I do believe that the Z1 also has EGR on it.

I'm sure the intake is tuned for low-rpm high velocity flow, though, keeping flow rates up under low vacuum, to increase VE.

That was also the case w/ the USDM D15B8 (HF engine) which also had EGR and smaller runners (cross-sectional).

[rkcarguy]

I think the motor is being confused with another, but yes you are correct about the intake, it is a larger size throttle body and intake runners as found on the y8. The head is also the same casting. The 3-stage vtec utilizes lean burn and a 2 valve swirl action just like the D15Z1, only they added a 2nd vtec solenoid to kick yet another set of lobes into action and provide approx 128HP. Research 3-stage vtec on google there is good articles and some claim near 50mpg in the stock 4dr m/t versions at 50mph.
The ecu for these is VERY rare and I'm going OBD-1 anyway so it's not a concern of mine. I will probably be using a D15Z1 ecu and installing a VAFC to activate the 2nd stage and enrich fuel mixture. In the meantime we have to see if a regular vtec ecu can be tuned to read a wideband o2 sensor, if so my tuning buddy can use a acura GSR ecu, the intake butterfly control to switch to 16V and the vtec function to grab high cam....

[rkcarguy]

Purchased a used Autocad program yesterday, let the design fun begin.
I did some sketches monday night using scale "block outs"(basically a square/rectangle shape representing the space items take up) of the engine swap wheels and components, plus one of myself. It doesn't turn out too bad.

I'm wondering...more of an aero question though, would it be beneficial to have 2-3 sq/ft of the front bumper open and allow air to flow thru the car via a channel which would pass between the occupants, then widen and flatten passing air under the engine and ultimately right under the exhaust system?
I'm thinking it would decrease frontal area and also counter the wing effect of the cars overall shape providing more neutral aero package at freeway speeds...

[theunchosen]

I'm not sure I caught it quite right. You said you were planning on building an Aluminum frame and then making a mold or having a mold made for composites(CF)?

Two seater and as long as you keep the weight of everything low enough you can go total CF chassis/body and it will be as light as you can possibly go(at this point).

If. . .IF you are really interested. . .and it sounds like this project will take time to start with you could wait for CNRF(Carbon-NanoTube-reinforced-Fiber) which is cast to be at least 10 times stronger than CF and lighter still. That would allow even less material to be used, and it would still weigh less. Albeit. . .it would be pretty enormously expensive.

OH I forgot, with the CF though since you have a CAD package there are alot of Chinese manufacturers that will produce a CF monocoque just based on CAD images.

The advantage of the CF monocoque is you can get down below 1kip. Aptera Motors has a Cd of .15.

Something to consider before you spend a chunk of change on aluminum