K20 mx5

[madjak]

Hi guys,

I'm looking to fit a k20 motor into my MX5. I can now get all the conversions parts from the US. I'm looking for clean, free reving N/A power for use on a track / sprints. I'm not familiar with honda engine so here's a few noob questions:

1) Where to buy a K20 motor. Seems there aren't many in the classifieds etc. Can you import them or are there other sources in Australia? I'm looking for just a long block, so no transmission, exhaust, IM.

The K20 will bolt up to the stock transmission which is good for a max of 250HP. So I'm looking for an engine with around 230-240HP. Now the IM won't fit into the car so I was actually looking at ITBs or fitting a S2000 IM. so my next question is:

2) what should I actually look for in terms of getting to 230 HP. K20a, K20a2, K20z1 etc all look to get around 200HP as stock, so is any preferred for minor tweaks? Would ITB's and ECU be enough to get it one to my 230HP target?

3) instead of doing all this myself, should I just get a built motor? ie spend more now to save later.

4) Revs, Revs, Revs... I like them, so what upgrades would be best? Lightened rods, rockers, better valve springs, cams, Kpro?

cheers

edit: and I don't want to fit a K24 motor. I want to stay in the under 2000cc class.

[EKVTIR-T]

getting an engine,you could buy a removed motor from one of the tuning shops,they sometimes pop up for sale but its a big gamble on the motors health as some on this forum have found out

a better way is buying a damaged donor car with the k20 like integra type R or S and civic type R

230hp is easy with basic bolt ons and tune,no need for ITB really

and exactly how high do you wish to rev? that also depends on your gear ratios and where you want to be


btw which mx5 chassis? NA I assume?

[mocchi]

you have a budget?

[Chernoby1]

Not related to the engine, but i would be worried about the gearbox taking "250 hp". HP doesnt really break boxes so much as torque does and youd be surprised at the amount of torque that can come out of these engines (~200nm).

Getting your hands on A k20 isnt the cheapest of endevours so i would personally recommend a destroked H22a (aka an F20b)

[madjak]

Yes NA... Gearing I'm not exactly sure how that will all work with the existing gearbox, 4.3:1 diff and 15" rims.

The reason for the ITB's is to fit into the engine bay. Seams a nice way to get around the IM issues (standard intake would be through the firewall at the rear of the engine). Alternatively, I can get an adapter to fit a S2000 intake which would sit correctly. I like the idea of the ITB's as it's not going to be driven much on the street.

Can you get halfcut imports or would I need to look for a write-off locally?

[madjak]

If the transmission can't take the power, remember the mx5 is pretty light and I am a gentle driver (or try to be), I can put a 6 speed MX5 box in which will take more power. At this stage, I'm trying to keep costs manageable to start with, and then upgrade later, which is why the K20 is a good starting point. Eventually it would be nice to get 280+ HP but thats later down the track.

Costs will start to build up, thats really why I'm posting now to get an idea of the engine costs. I know everything else I need and it's not going to be cheap.

[u mad?]

i have a jdm k20a ( higher comp, better cam) for sale atm, if buyer falls through i will pm you

[madjak]

For comparison, my stock 1.6l mx5 motor will only get around 130hp so this will be a substantial upgrade. Turbo upgrades will get the little 1.6 engine up to around 240-250 at which point things will start to fail, like the rods, or the gearbox.

It may be that the first stage is just the stock engine, then look at options for more power / revs later.

A stock K20a / K20a2 your looking at 7,500rpm ish, maybe 8000 with an ECU, is that right?

[lolmclol]

http://www.k20a.org/forum/showthread.php?t=112309

do it OP

[madjak]

http://www.k20a.org/forum/showthread.php?t=112309

do it OP

Yes that is the kit... however there would need to be a few mods to that to fit it into a RHD car. Power Steering and exhaust don't fit.

[Stevil]

Well I dont see turbo mx5 gearboxes failing with normal abuse so a K20 is hardly going to change things. whats ya location Madjak, what classes r u thinkin of competing in should you do the swap ?

[madjak]

Well I dont see turbo mx5 gearboxes failing with normal abuse so a K20 is hardly going to change things. whats ya location Madjak, what classes r u thinkin of competing in should you do the swap ?

I'm in Perth and currently doing club track and hill climb events as well as a speed series.

I would basically go into an outright (closed body) under 2000cc class in the speed series, which puts my up against some pretty quick cars. I currently run against AE86 and Lotus which makes it hard to compete. I really don't know how the mazda would perform with a K20, though I suspect it would be pretty fast. Light, low and able to get the power down quickly out of the corners. The turboed 220HP ones put down some pretty good times, and I think the NA K20 would be more drivable.

Currently the car is road registered so I would probably try and keep that subject to getting all the right approvals.