Tuning direction dilemma

[Sway]

The agreement with my better half when I got my 5 went thus: "fine, I'll sell my kit car that you hate, as long as I can tune the hell out of the Five...".

So,agreement made, I've been researching and planning upgrades - while the existing engine has done it's best to piss me right off. Head gasket, coils, now piston rings.

Plan had been to keep this engine going (I do a 100 mile a day commute) whilst waiting for a lovely chap named Bruce to finish renovating his house so he could supply me with a kit to swap in a Jag 3l v6.

However, in the last week I've been offered a lovely low mileage but same year engine for mine, which I'm going for as I'm really starting to think my current engine is doomed. I've also seen that TDR are very close to releasing what looks like the definitive rotrex kit, offering 230-240 bhp at the wheels...

So, do I just drop this new engine in temporarily, using it as an excuse to upgrade the cooling system (which I'll keep for the Jag engine), or go in a completely different direction (saving about 1-2k) and treat this engine real nice (manifold/intake/cops/ecu plus new rad and hoses) before bolting a rotrex into it in a couple of months?

I wanted three things: around 250bhp at the fly. Clean, crisp throttle response without big spikes in torque (hence turbo is not an option). Great soundtrack.

Seems the rotrex will give me two out of three, and a decently piped 4 pot doesn't sound that bad...

Thoughts?

[knitware]

Sway said:

crisp throttle response without big spikes in torque (hence turbo is not an option)
Thoughts?

Yes, consider turbo as an option. Modern turbos won't spike instead spool nicely with linear pull and no surprises.

[VladD]

Who is this Bruce chap and do you have a link to the kit?

[Sway]

Goes by Rocketeer on Instagram, M-tech have a build thread for the prototype on Mx5nutz.

He doesn't post much, or do anything in the way of marketing - he's ready to do a 'refined prototype' kit and responds well to pms via Nutz.

Bill of materials includes absolutely everything to do the conversion, minus the engine itself. Not cheap though, could easily build a forged turbo setup for the same cash.

[binnerboy]

I guess it depends on how much money you have if the answer is loads then do this

https://www.flyinmiata.com/V8/index.php

at the other end of the scale Mtech will do a drive in drive out TD04 conversion for about £2k plus VA and you supply the TD04.

http://mtechautomotive.co.uk/mx5-turbo-conversion/

check out the build threads on Nutz , going down the jag v6 route sounds expensive.

I think 230 is doable on standard engine internals though I am no expert.

cost it all out, if you are doing the work yourself then it will just be time and parts.

someone with an conversion kit for a rotrex

http://bmmperformance.co.uk/product/mazda-mx5-miat...

not quite your HP needs but they are working on a kit with a C30 that might meet your needs

I have on idea if bmm are any good, a mate has used mtech and rates them

Edited by binnerboy on Wednesday 22 June 13:52

Edited by binnerboy on Wednesday 22 June 13:52

[Sway]

Cheers, turbo is definitely out. I've not driven a single turbo car that doesn't have what feels to me like a 'soft' accelerator. That includes modern hybrids, variable vane, etc.

The rotrex kit I'm thinking of is this one: http://trackdogracing.com/rotrex.aspx

They've been developing it for years, and it even includes bonnet props and airflow slam panel.

First customer installation here (he's an experienced Guinea pig, and his feedback will be taken on board for the imminent full release): http://forum.miata.net/vb/showthread.php?t=612364

I'd love a V8 conversion, but it involves chopping into the firewall, which is automatic IVA. No thanks.

[binnerboy]

that kit looks awesome

Good luck with the build :-)