Engine Conversion - How to Know What Will Work?

[Chunkychucky]

Firstly apologies for the banal question (didn’t come across anything conclusive after a Goggle) and secondly apologies if this is in the incorrect sub forum.

I’ve got an engine conversion I’d like to do (nothing ground breaking, swapping one manufacturer’s 4 pot for another manufacturer’s 4 pot), however I’d ideally like a better gearbox to go with this (RX8 6 speed or similar). The benefits in my mind of this are an extra ratio to enable better cruising, more gears so better ratios for the type of high-revving N/A engine i’d like, and stronger overall so better-suited to the intended use/abuse the car would get.

Aside from the physical issues of trying to fit the gearbox in the car (99% sure the tunnel would need re-doing for both the gearbox and bellhousing), what other considerations do I need to look in to? Do I need to look in to the length of the input shaft on the gearbox, possible clutch mechanisms/release mechanism dimensions etc.?

Before I settle on one gearbox in particular, I’d like to get a list of things together to check so that I can make the decision process a bit easier.. any assistance appreciated

[Fleckers]

your tape measure will tell you what will fit and what will fit after a lot of angle grinder work

putting a nice rear wheel drive engine and gearbox in a front wheel drive configuration is a LOT of work

there are plenty of bell housing adapters to help you fit engines and gearboxes together then you need to make up the mounts etc etc etc etc and then tell your insurance company who may not be very happy

[stevieturbo]

Chunkychucky said:

Firstly apologies for the banal question (didn’t come across anything conclusive after a Goggle) and secondly apologies if this is in the incorrect sub forum.

I’ve got an engine conversion I’d like to do (nothing ground breaking, swapping one manufacturer’s 4 pot for another manufacturer’s 4 pot), however I’d ideally like a better gearbox to go with this (RX8 6 speed or similar). The benefits in my mind of this are an extra ratio to enable better cruising, more gears so better ratios for the type of high-revving N/A engine i’d like, and stronger overall so better-suited to the intended use/abuse the car would get.

Aside from the physical issues of trying to fit the gearbox in the car (99% sure the tunnel would need re-doing for both the gearbox and bellhousing), what other considerations do I need to look in to? Do I need to look in to the length of the input shaft on the gearbox, possible clutch mechanisms/release mechanism dimensions etc.?

Before I settle on one gearbox in particular, I’d like to get a list of things together to check so that I can make the decision process a bit easier.. any assistance appreciated

You need to look at everything that will be different.

If you've zero knowledge of such things, then find people who do, with whatever engine/box/car configuration you want, and ideally buy a kit of parts to make it happen, or pay those people to do it for you.
Ultimately almost anything can be made to work with enough time, skills and money. Or none will work with a lack thereof.

From an initial first post, you do seem quite out of your depth though.

Swaps can be easy or hard, and many places in between. Well not often that easy really.

Either get a full kit, or full engine/box from a single vehicle.

Of course, if you elaborated on what car, what engine, etc etc.....then maybe people could point you in a better direction

[Ryyy]

What is the swap?

[E-bmw]

Why make it EVEN more difficult by choosing an engine & gearbox separately?

There may well be MANY hidden issues/incompatibilities.

Just find a car that has both of what you want & keep them together, get the wiring loom & ECU.

Then open your wallet & wave goodbye to any & all free time & money for the next year.

[Tony1963]

E-bmw said:

wave goodbye to any & all free time & money for the next year.

I so love an optimist

[5s Alive]

Tony1963 said:

E-bmw said:

wave goodbye to any & all free time & money for the next year.

I so love an optimist

I think E-bmw is being overly optimistic.

[stevieturbo]

5s Alive said:

I think E-bmw is being overly optimistic.

Yep, could be 2-3 years lol

[richhead]

Chunkychucky said:

Firstly apologies for the banal question (didn’t come across anything conclusive after a Goggle) and secondly apologies if this is in the incorrect sub forum.

I’ve got an engine conversion I’d like to do (nothing ground breaking, swapping one manufacturer’s 4 pot for another manufacturer’s 4 pot), however I’d ideally like a better gearbox to go with this (RX8 6 speed or similar). The benefits in my mind of this are an extra ratio to enable better cruising, more gears so better ratios for the type of high-revving N/A engine i’d like, and stronger overall so better-suited to the intended use/abuse the car would get.

Aside from the physical issues of trying to fit the gearbox in the car (99% sure the tunnel would need re-doing for both the gearbox and bellhousing), what other considerations do I need to look in to? Do I need to look in to the length of the input shaft on the gearbox, possible clutch mechanisms/release mechanism dimensions etc.?

Before I settle on one gearbox in particular, I’d like to get a list of things together to check so that I can make the decision process a bit easier.. any assistance appreciated

Unless its a special car it would be cheaper and a lot easier to just buy a car that has what you want.
If its just because, then try and do a swap that someone has already done.
The biggest hurdle on modern cars is the electrics.

[Retro_Jim]

Chunkychucky said:

Firstly apologies for the banal question (didn’t come across anything conclusive after a Goggle) and secondly apologies if this is in the incorrect sub forum.

I’ve got an engine conversion I’d like to do (nothing ground breaking, swapping one manufacturer’s 4 pot for another manufacturer’s 4 pot), however I’d ideally like a better gearbox to go with this (RX8 6 speed or similar). The benefits in my mind of this are an extra ratio to enable better cruising, more gears so better ratios for the type of high-revving N/A engine i’d like, and stronger overall so better-suited to the intended use/abuse the car would get.

Aside from the physical issues of trying to fit the gearbox in the car (99% sure the tunnel would need re-doing for both the gearbox and bellhousing), what other considerations do I need to look in to? Do I need to look in to the length of the input shaft on the gearbox, possible clutch mechanisms/release mechanism dimensions etc.?

Before I settle on one gearbox in particular, I’d like to get a list of things together to check so that I can make the decision process a bit easier.. any assistance appreciated

Is this for your A series?

From my own experience as you've seen it can be done but takes time and I'm still finding things out that I didn't account for but my criteria was as follows:

Ratios
Clutch actuation (cable/ Hydraulic)
Availability of gearbox/ spares/ service items etc
Clutch diameter
Overall dimensions
How modifiable is the gearbox i.e. the gear stick position

The prop was the easiest part as I didn't make it and was a simple phone call whilst I laid under the Cortina giving the relevant dimensions.

The hardest was the adaptor plate - getting it central and then making it a repeatable process when transferring from the wood to 1.5mm steel to 6/8mm (I do have the stud pattern for the MK1/2 MX5 gearbox drawn up on CAD now)

The odometer is being particularly frustrating currently as I don't want it to look different from the factory unit but the cable speeds are different between the Ford and the Mazda so I am planning on a modern GPS unit with a new face attached but making that face is the stumbling block.

I'd avoid the RX8 gearbox based on its size - it's quite wide at the bell house but not much different in length from a MX5 or ford 2000e surprisingly

I tried to keep as much of these parts as standard as possible like the clutch fork and slave cylinder so that it could be repeated should I wish

[stevieturbo]

Let's face it, he's given zero information as to what he's really doing to help.

And speedy is easy enough, Speedycables can modify the speedo head so it will read whatever you want