Hi guys,

Just curious as to why people do not do DOHC conversions?
The Hyundai Sigma engine is DOHC and is a 6G7X engine, does anyone know if their heads can be used?

there has been a few dohc conversions done, i believe most of the issue is finding dohc engines in aus. here in nz there is heaps of them, hence the reason i bought a dohc jdm Diamante.

Im mid way through build of DOHC 6G72 TT into a 2nd gen.

Cant confirm if the heads will fit from the Hyundia 6G7X engine. What gen magna are you looking to go DOHC?

I have heard about people trying to use DOHC heads from the pajero's as some as the same engine numbers
Tho i dont know if anyones actually done the converstion

I am not interested in the conversion, I am just curious as to me it seems like a good upgrade that everyone may be overlooking

I'd really only go DOHC for the rev factor, not really the added power.

For the sameish cost you could grab Pajero pistons and retune.

I found a video on youtube showing a DOHC Diamante, its a 2.5, looks just like a KE/KF Verada with the blackout dash, its a little sad as these fools destroy it with a forkfilt, it looked in good nick before the forklift attacked it, if you want to see the video just do a youtube search for "Diamantes não são eternos "

Actually the JDM spec Diamante had the DOHC 2.5 and made 150kw or so as well.
Not only that but they even had double wishbone suspension at the front rather than the Aussie spec MacPherson strut

I watched that video and it is a real shame what those morons did :(

the DOHC 3l produced 166kw or so stock, the DOHC 3l Mivec 199kw (only available in the Diamante 30M), the DOHC 3.5l 194kw, and the DOHC 3.5l mivec 206kw (only available in the pajero EVO). I love my 3l mivec, loves to rev and alot of low down torque as well.

Thats pretty powerfull for a 2.5 litre, i think my KH 3.5 is only 140kw, be interesting to see how that car in the video went, shame those idots destroyed it. I guess the car in the video would be a japanese made car as the Diamantes made in Australia had the same motor as the Australian made Magna/Verada


Actually the JDM spec Diamante had the DOHC 2.5 and made 150kw or so as well.
Not only that but they even had double wishbone suspension at the front rather than the Aussie spec MacPherson strut

I watched that video and it is a real shame what those morons did :(

You guys should think about 3.8 or 3.8 Mivec? 3.8 after tune etc... would be making about 190+kW at the fly, with a very solid torque curve that you wouldn't see in a 3ltr

I'd like to see what sort of numbers savage3 makes on his Mivec 3.8...

the 3L MIVEC engine makes 199kw stock, and is one of the last mitsi engines to have mivec on both intake and exhaust. plus is a much less sophisticated system, less setup hassle. 12v signal to activate cam changeover, as opposed to working in the variable cam timing etc on the 3.8l. would love to see results on a properly setup 3.8l

btw I forgot to ask, someone mentioned using Pajero pistons. What is so special about them exactly to warrant fitting them into a 6G74?

It ups the compression i believe, since 74 magna pistons are domed.

DOHC 6G74s are excellent, but a 3.8 conversion will yield easier results and a very chunky and flat torque curve that cant be matched by a smaller capacity MIVEC engine. Displacement rules.

Yes displacement can rule, but for ease of installation a 3l mivec is a factory made engine, with proven performance. Id rather start with that base and use funds to increse power, rather than to try get the other engines to the the level the 3l performs at reliably already.

the 3L MIVEC engine makes 199kw stock, and is one of the last mitsi engines to have mivec on both intake and exhaust. plus is a much less sophisticated system, less setup hassle. 12v signal to activate cam changeover, as opposed to working in the variable cam timing etc on the 3.8l. would love to see results on a properly setup 3.8l

Hai. The 3.8L Mivec has two cam profiles. It's either one or the other. Change over is somewhere between 3.5-4k and is also controlled by a 12v signal. Stock output is at 196kw according to the wiki. Only prob is the mounting the ignition hardware, but I have it mostly sorted. Drop it straight into a 380 and you'll only have to worry about the changeover + tune.

Yeah true, i believe the 3.8 has variation on cam timing as well. It also only has the extra lift lobe on the intake side, not exhaust

Yes displacement can rule, but for ease of installation a 3l mivec is a factory made engine, with proven performance. Id rather start with that base and use funds to increse power, rather than to try get the other engines to the the level the 3l performs at reliably already.

A 3.8L engine straight from a 380 is going to be more powerful in a large car like a Magna than a 3L MIVEC engine. You're talkinng about a difference of around 80-100Nm over a wide range of RPM and very little difference in top end power.

I'd much rather start with the 3.8L as torque is where it's at.

yeah, the 3.8 has 342Nm , and the 3l mivec has 301nm @ 4500rpm. as a starting point i believe they are pretty close, and having the free revving ability of the 3l is a bonus, depending on your driving style. i just prefer the 3l for the mivec on both intake and exhaust, and the 3l been dohc, has more room for individual cam tuning. i would love to get an AWD jdm spec diamante here in NZ , drop in the 3l and then add some sensible boost, be a great car.

Yup and then chuck up the torque delivery graphs and see how peaky the MIVEC engine is compared to the SOHC 3.8. It will be like night and day i imagine

and thats when personel preference comes in, i love the high revving nature of the 3l, mivec changeover doesnt occur till 5500 rpm, although peak torque is reached at 4500rpm, the point the intake butterfly changes runner lenth i believe. would love to see someone do an all out build up of a 3.8l, whts the bore diameter? could the 3l mivec heads be fitted to the 3.8l block?

Why not have both? Mivec and 3.8L..
http://img543.imageshack.us/img543/6886/photo1uky.jpg

the mivec 3.8 is sohc, and has mivec lift on intake only. 3l is dohc and mivec lift on exhaust and intake. Comes down to personel preference i suppose, in short 6g engine in any guise is a great base.

robssei - I can see you love your car mate, and that's fine. After having a 3.5L ATMO Ralliart, then the boosted Evo, now a diesel ASX, I can tell you one thing for sure, and that is; torque rules. Every day driving commands torque. Maybe it's a personal thing, but I don't think it is. The more usable power you have down low, the better to drive any car will be.

Now, put a supercharger on a 3L DOHC MIVEC and give it more low end punch, then you have a winner.

yes torque is a great thing, and the mivec isnt as bad as one would assume, its better as my old 3.5l down low then from 3500rpm onwards it kills, although firgures say the 3.5 should have me off the line. Id love to boost a mivec, would be tricky but could go low boost or use 6g72 turbo pistons to lower compression and ramp it up. I have a mate who wants to slot my engine in an old galant rwd lol, now that wouuld be fun!

Best way to boost a small capacity V6 engine like that is to use a twin turbo setup like Black Beard has. 2 small turbos that come on very early.

That would be ideal, lack of funds prevent it lol.

Why not have both? Mivec and 3.8L..
http://img543.imageshack.us/img543/6886/photo1uky.jpg

Supercharged too???