Engine choices for a Se7en?

[GuinnessMK]

I built a bike engined MK Indy years ago, and really enjoyed track days and blatting about in it, but for various reasons it ended up being stored for several years.

Now I'm in the process of recommissioning it, but I can't help but think it's not quite me anymore. I'm a bit older, a bit less interested in outright performance and a bit worried that blatting about is a bit antisocial!

To be honest, not having a reverse gear, having to wear a helmet and the general fragility of the bike engine (or perhaps the way I built it), made every drive a fine balance between the exhilaration of the performance and the sheer awkwardness around the practicalities.

So, I'm considering changing the engine to a car engine / box and fitting a windscreen and doors.

Looking around, the MX5 is a popular choice, cheap, comes with a matching gearbox and there are parts available for the conversion, but it's potentially a little low on power? Although there is the possibility to turbo later on?

Zetec and Ford gearbox are similarly popular, but somehow a bit uninspiring? Duratec conversions look expensive.

Rover V8's are interesting, but I'm a bit wary of 1970's BL tech!

So, over to PH, what other RWD engines / gearboxes might be suitable for a 7 type car, focused more on touring, than trackdays? I've seen a 3.0 l Jag S Type for sale....

[Nigel_O]

Although the Zetec seems a little un-inspiring, with the correct mods, they can be very entertaining. Mine has Jenvey throttle bodies, a bit of mild headwork and a warm cam and gives 170+ bhp. It sounds pretty good, although a lot of the noise is induction. Its also exceptionally easy to drive at "normal" speeds - I purposely stayed away from BECs as I wanted the ability to drive it in traffic without having to dial in 3,000rpm just to move forward two car lengths in a queue.

I also stayed away from V8s, simply because I wanted the handling benefits of something lightweight

For me, the optimum engine would be a Honda S2000 - 240bhp out of the box, not enough torque to break traction after the first couple of gears and sounds epic when the V-Tec kicks in. Bloody quick too. Expensive lumps now though

If I was going to go with a bike engine, it would be something big - 1300cc to 1400cc, just to get the low-end grunt

[Frankthered]

If it were me, I'd have a serious look at the Renesis rotary out of an RX8 - not sure why more people don't think of these for sevens.

Might be a little bit too much like a bike engine still though?

I've often wondered why more people don't use the later Jag engines (even though they are Ford anyway) but do recall somebody on here stating that the gearing on the diff was a bit oddball, and that this was compensated by an equally (and oppositely) oddball final drive from the gearbox to compensate. Could make things tricky if you want to use the engine and the box?

[Bronco_jr]

I used a vauxhall C2.0XE or redtop. 150BHP out of the box or 210BHP with throttle bodies and a decent manifold.

I guess they're getting thin on the ground these days and that may make them expensive....

[Glasgowrob]

Rx8 engine and box is a sublime setup

And perfect for a lightweight kitcar

Engine issues aside it's a perfect choice donors are peanuts as well

[Olivera]

Millington Diamond 2.5

[Martin30]

I can recommend the MX5 turbo engine, having had one previously myself - though in an MX5, rather than a 7. Readily available, makes good power & torque on standard engine internals, gearbox and diff handle power well too, loads of installs completed to learn from, plentiful aftermarket support. Good choice.

The Fiesta ST 1.6T ecoboost engine seems to be gaining traction in the seven world, also. RWD gearboxes now available for sensible money.

I have a Corvette LS2 V8 in my seven, and can recommend that too. Surprisingly light and compact engine for its 400bhp/400lb-ft, though it does require a physically large gearbox to handle the torque. The weight does not overwhelm handling, but its torque certainly can, so requires a little delicacy on track. Not the most simple conversion though.

How about turbocharging/supercharging your bike engine to bolster torque? Might be cheaper and easier, with an electric reverse fitted?

Martin

[GuinnessMK]

Thanks all,

I've looked at the zetec install before, but by the time you add throttle bodies and an ECU, it starts to become a bit expensive just to get running, and then any performance mods come on top of that.

RX8 might not give me the reliability I was hoping for! Honda2000 / Redtop and Millington are a bit rare / expensive.

I'm being drawn more to the MX5 first, with the option to force induction later if I need more power.

Can the MX5 run on it's own ECU / throttle body, or does it need a standalone set up?

Cheers

[anonymous-user]

If I was changing engine is look at an mx5, but that as no way my zetec with Omex bodies could be described as boring or mundane and has plenty of oomph for the road (180 bhp) without needing to add performance parts

It's also a well known combination which is always a good thing.

[Frankthered]

GuinnessMK said:

RX8 might not give me the reliability I was hoping for!

What makes you say that? Tip seals?

OK, it would make sense to budget for an engine rebuild (£1300-1800) but once done, that should last for about 60000 miles - how many miles are you planning to do in your seven?

230 bhp out of the box in a lightweight engine. OK, it will use oil because that's the way it's designed but I'm genuinely surprised more people don't use these in kits. I guess the different technology puts people off.

They also sound awesome IMHO!!

If you want to stay more conventional, Zetec and Mazda are classic suggestions, you could look at the Duratec (expensive?) too or maybe a BMW straight 6 you can get one to fit.

[Justin S]

Glasgowrob said:

Rx8 engine and box is a sublime setup

And perfect for a lightweight kitcar

Engine issues aside it's a perfect choice donors are peanuts as well

If you are registering a new vehicle , I suspect they will struggle with the Rex on noise and emissions .

I went S2000 for my Westfield and the cost of the engine is crazy. I spent £3.5k on a 45k engine , but £3.5 would get you a 100k plus engine now. My last car was a black top Zetec and was pretty good and if I still had it, would have been supercharged too. It made 185 bhp on Jenveys at Northampton Motorsport rollers.
Mazda SDV Westfields are a great car to build . You can easily add turbos or superchargers afterwards too.

[FlossyThePig]

Boring Old Fart said:

In the real car world a Se7en is an Austin Mini

[Bronco_jr]

[hkp57]

I am running a Busa engine now, if I were to start again it would be the 1.6 Ecoboost with standard internals 330bhp

[GuinnessMK]

hkp57 said:

I am running a Busa engine now, if I were to start again it would be the 1.6 Ecoboost with standard internals 330bhp

Interesting, what gearbox / adaptor can you use and what ECU?

Cheers

[Black_S3]

Given what you’re asking it sounds to me like there’s no need to reinvent the wheel attempting rx8, s2k or st conversions as the cheap & trusty Zetec would tick all the boxes you mention?

[shirt]

I have a duratec in mine and would take one any day of the week over a zetec.

I would, however, consider a 1.6 ecoboost. Still ford so a sigma to type 9 bellhousing is available off the shelf. Easily tuned to 300bhp/300lb ft and weighs around 115kg dressed. Paired with a decent ecu you can have as many maps as you like to tailor the power level to how you’re feeling thay day. Very flexible engine.

Its the engine i am currently favouring for my radical sr8 roller. Should fly.

[Lordbenny]

Olivera said:

Millington Diamond 2.5

If you’ve got a spare £23,000!