6A12 Mivec 2ltr V6 Performance

[VR4WGN]

sweeeet

[Turbo_Steve]

Agree with John 100% - tuning blindly one someone elses car really isn't any fun for them, and is liable to be expensive for you if it doesn't deliver results or, worse, delivers a lump of scrap metal under the bonnet.

Some of what you're discussing doing is advanced stuff that an experienced mechanic would approach with extreme caution and deep pockets, even on their own car.

I'd make your money on servicing and fab for now, and bring on a good mechanic if/when it makes sense financially..

[AlanDITD]

pants submariner......??

[Dom B]

The throttle body set up i was talking to achieve 20-30bhp increase in a Normally Aspirated car is 6 individual throttle chokes alongside a programmable ecu. Just having a bigger single throttle body will gain some but no where near as much and big single throttle bodies are awful to drive.

[Turbo_Steve]

Wow: yes they can give a huge increase in power (and, coincidentally, sound flippin amazing!) but they are dead pricey, not least as you will need to chuck the factory ECU in the bin as it's extremely difficult getting the MAF to work right with this setup!

[Dom B]

I'd chuck the maf and just use speed density perhaps. Our cars are old enough to not be too difficult on the emissions. But yeah be prepared to spend about £2-3000 plus plenty of dyno time to set it up.

[VR4WGN]

thanx for that guys,i see where your comming from with your replies,but at the same time what would changin a few things do? i mean really only talking some performance mods,ie air system,exhaust,throttle(single larger),maby some cam grinds, surely this wont fark the engine surely?

[Nutter_John]

Have you not listened to anything said ?

why not go join a forum that supports this engine and ask the same question of them

[Turbo_Steve]

surely this wont fark the engine surely

That's the point: you don't know. At the very least you need to understand what fitting various components does to an engine. With the best will in the world, mate, I would expect anyone working on my car to have a fundamental understanding of how that engine works: of why CamShafts are setup the way they are, of why a particular displacement / rod length / valve profile / boost pressure was chosen, of why an exhaust manifold is the length and diameter it is.

Everything on a car, EVERYTHING is a compromise of some sort, whether it's cost vs performance, driveability vs peak power, handling vs turning circle etc etc etc.


At the very least you need to undertstand why changing a camshaft could result in leanness that the ECU isn't allowing for, and blow the bottom end out.

I'm not having a go at you, Q, but you have to learn to walk before you can run, or you'll find yourself forking out to repair other peoples engines.

[VR4WGN]

i fully understand that Steve and your right in what you say so no offence taken dude,i woulnt risk it on a customers car,but being my own i thort itd be my own fark up if it did ritght? so maby i should just stick to the typical upgrades then maby?? exhaust etc then,that way like you sa yit wil be 1 less expense should anythig go wrong lol..

[fuel]

Hey mate, I feel I have quite a bit of knowledge regarding 6A12 MIVECs as I've owned four of them, two of which I still currently own and one of those I've just recently rebuilt.

If you're just dropping the 6A12 into your Legnum then I'm sorry but you are going to be severely disappointed with it. The power delivery of the 6A12 is best suited to a light car like the FTO or even a Mirage/Lancer.

The two 6A12 MIVEC's I own are factory fitted into E54A Galant VX-Rs, one manual weighing 1270kgs and one auto weighing 1290kgs and you can definitely feel the extra weight the Galant has over the FTO, let alone a Legnum.

Be careful with enlargening the throttlebody, the max you can go is 62.5mm and at that size you'll run into idle problems and low rev drivability issues. The factory throttlebody size is 54mm while a plain non-MIVEC 6A12 is 60mm strangely enough, and to be honest I couldn't really feel the difference between the two, if anything it ran better with the 54mm throttlebody.

The stock headers could definitely do with work, RPW make some off the shelf replacement performance items but they are a bit spendy. You really want some headers which have long primaries and almost as long secondaries, but given the layout its not easily achieved at all.

Many 4G92 MIVEC owners have tried going ITB's, but have gone back to stock single throttle plenum setup as there were no gains to be had and drivability was heavily sacrificed. But a high revving V6 on ITBs would sound so fricken hot!

Stock they are supposedly rated at 200PS @ 7500rpm but everyone who dynos them can't get more than 150hp at the wheels with them.

I notice a few of you guys are talking about MAFs with them, the MIVEC engines don't have MAFs instead they use a MAP sensor.

Also if you start pushing the 6A12 MIVEC expect to be replacing the big end and main bearings frequently, while they are the same width as 6A13 bearings the crank journal size is quite a bit smaller in diameter and as a result they have about 30% less surface area. I don't know the size of 6A13 rods but the 6A12 rods are scary thin, they resemble pencils. Put it this way, a stock automatic VX-R managed to do this http://i97.photobucket.com/albums/l2...VX-R/sump1.jpg and this http://i97.photobucket.com/albums/l2...-R/pistons.jpg

And finally, be prepared to constantly be setting your tappets and other niggly things like that. As they don't have hydraulic lifters they have manually adjusted tappets due to the rocker arm design, and the tappet itself comprises of a two piece setup with a foot attached to the bottom retained with a plastic (yes, PLASTIC) clip around it which is meant to look like this new http://i97.photobucket.com/albums/l2...nt/tappets.jpg but ends up looking like this within a few kms on the clock http://i97.photobucket.com/albums/l2...R/DSCF1557.jpg, the plastic bit always breaks and drops down into the sump and the only thing holding the bottom foot of the tappet on is the clearances and if the tappet clearances grow too large then out slips the foot down into the sump too. Oh yeah, and to fix that up requires the removal of the cambelt and the upper 'cam tray' of the head to be removed, flipped upside down and a new tappet screwed in place, these next few pics should give a general idea of the job - http://i97.photobucket.com/albums/l2...R/DSCF1562.jpg http://i97.photobucket.com/albums/l2...R/DSCF1550.jpg and http://i97.photobucket.com/albums/l2...R/DSCF1554.jpg

Right, sorry for the essay but I hope I've given you some insight.

[fuel]

also if you want more info about the MIVEC engines then definitely join the www.mivec.co.nz forums where I am a friendly moderator there.

[scott.mohekey]

I had it in my head that Q was planning on putting the mivec heads on an NA 6A13 block. Is this not the case?

[Nutter_John]

I had it in my head that Q was planning on putting the mivec heads on an NA 6A13 block. Is this not the case?

Thats another fantasy island project he mentioned

[fuel]

I dunno I just thought from reading this thread he was wanting to drop a complete 6A12 MIVEC into his Legnum, unsure if his Legnum is 2WD or 4WD.

[fuel]

and I don't know if anyone has successfully finished off a 6A12/6A13 hybrid yet, I know Goku is doing one but don't think he is finished and has it running yet.

[scott.mohekey]

Kayne's is a 6A13TT engine with just a couple of bits from a 6A12TT, namely the rocker covers, oil pump, and maybe a few other small bits. He is mating it up to a 7g drive train though.

[scott.mohekey]

I only assumed Q was putting the mivec 6a12 heads onto a 6a13 block because I couldn't see the point of putting a mivec 6a12 into a legnum.

[Confused]

I did always want to put a 6A12 MIVEC into my Carisma, many times did I discuss it with my dad!


That would have been a nice upgrade from the 1.8, and would have sounded amazing!

[fuel]

Kayne's is a 6A13TT engine with just a couple of bits from a 6A12TT, namely the rocker covers, oil pump, and maybe a few other small bits. He is mating it up to a 7g drive train though.

Oh right it's been a while since I've had a chat with him for some reason I thought he was doing a MIVEC 6A13TT hybrid, although he was being quite secretive with his engine build.