Im in the process of rebuilding a 6g74 for my TJ, trying to get as much power out of it as i can afford so far i have:

New valves, water pump, oil pump and distributor
10.5:1 Comp pistons
Heavy valve springs
ARP rod bolts
272/300 Cams
Full gasket and engine bearing kit

The block will be bored and honed to fit the pistons as there oversize and i plan on getting the heads worked
Is there anything else i should do while i have the engine apart ?

Hey dude, take a look at Jasons VRX's mod list - http://www.aussiemagna.com/forums/showthread.php?t=65423

Sounds interesting... make sure you post up results/dyno sheet etc. when you have it all back together.

And definitely check out the above thread...

You could look at a short ram modified intake?
Hope you have the ECU side of things sorted out.
Pretty sure they will bolt on, but the 380 heads are supposed to flow a HEAP more compared to 74 heads.

You could look into 1mm+ oversizes valves aswell but have been reading and on the 74 motors doesnt seem to be worth the gain had.

I have a haltech interceptor but being in tassie im pretty limited to dyno's so getting it tuned is a problem
How much will a set off 75 heads set me back ?
Also is there anything i can do or get done to the crank for performance ?

When you say short ram do you mean modify the stock unit ?

I have a haltech interceptor but being in tassie im pretty limited to dyno's so getting it tuned is a problem
How much will a set off 75 heads set me back ?
Also is there anything i can do or get done to the crank for performance ?

Interceptor wont be enough. You would want something that has full control of over ignition timing and injector timing not to mention anything else, A full ECU or even an SKR re-flash would be more suited.
75 heads, no idea mate, best give the loacl Mitsu a call.
Crank, I'm by no means an expert but you can get it balanced up.
Getting all the engine parts balanced would be a good avenue to go down aswell.

Would it be more cost effective to swap the 6G75 instead of rebuilding the 6G74?

A 6G75 wont put out as much power as this setup and the lack of performace parts plus the price of one doesnt make it worth it at the moment, Im doing everything myself so its not going to work out to expensive

if you haven't ordered pistons already, go for a 6G75 crank, offset the piston pin by 2mm and then you've got a stroked 6G74... can get up to 4L in NA guise (+4mm stroke, +4mm bore), but realistically I'd be worried about 4mm overbore. 3.8L is easily attainable though.

would be nice to see someone in AU do it

Thats definatly something ill think about
any ideas on how much a 75 crank would be worth ?
i have the pistons ordered already though :mad:

also being a 75 crank wont the powerband move down the rev range a bit in a motor thats already going to have to be revved pretty hard to make good power with the cams iv selected

Care to say how much the prats are costing & where you're getting them through?

Im sourcing the valves, water and oil pump, gasket kit and arp rod bolts from america through ebay, its pretty cheap and if you look hard enough you can find decent brand parts not just some generic brand, the pistons, valve springs and cams are from RPW so fingers crossed

Im sourcing the valves, water and oil pump, gasket kit and arp rod bolts from america through ebay, its pretty cheap and if you look hard enough you can find decent brand parts not just some generic brand, the pistons, valve springs and cams are from RPW so fingers crossed

Good luck with that! Not that it'll be much better, but you're probably better off dealing with Tighe direct - because if RPW's are wrong, they'll send you to them to iron out the problems anyway.

there is a member on here that use to work for mitsubishi ,cant for the life of me remeber his name, but i read somewhere that he stated that he had built a few naturally aspirated magna engine's that were pushing out 200-240kw ,hopefully another member will remember this person and point you in the right direction or the guy starts reading this thread.... anyways goodluck..

Good luck with that! Not that it'll be much better, but you're probably better off dealing with Tighe direct - because if RPW's are wrong, they'll send you to them to iron out the problems anyway.

Wasn't there mention that RPW doesn't deal with Tighe anymore, they deal with someone else now?

there is a member on here that use to work for mitsubishi ,cant for the life of me remeber his name, but i read somewhere that he stated that he had built a few naturally aspirated magna engine's that were pushing out 200-240kw ,hopefully another member will remember this person and point you in the right direction or the guy starts reading this thread.... anyways goodluck..

Jason aka Jason VRX

iv had a chat to (jasonsvrx) he gave me a few pointers,
Iv also decided to stroke it with a 75 crank, i was told $1200 from mitsubishi so i might go down that path ill regret it later on otherwise, i heard RPW are using camtech now ?

.......i heard RPW are using camtech now ?

That may be the case now, but in the past, if you had an issue with one of their 'performance' parts, they put you onto the company that made/ supplied it for them. You had to resolve the issues yourself. Things may have changed in that department also........:hmm:

I have what you would call a Hi-po na build and I think it gets somewhat boring because it's too linear, although it makes it nicer to drive it's not as fun. Saying that I did buy it built.

Mine has 380 injectors in it with a skr tune and runs great. Afaik it has the facory crank in it though

Yeah i was thinking ill soon get over the extra power and want more so i was thinking of rebuilding the engine that will come out and setting it up for FI its all up to how much money i want to pour into my magna...

Yeah i was thinking ill soon get over the extra power and want more so i was thinking of rebuilding the engine that will come out and setting it up for FI its all up to how much money i want to pour into my magna...

You cant have a Hi-po NA car set up for N/A major point being for FI you want something like 8:1 and for NA you would want 10:1

;1241495']You cant have a Hi-po NA car set up for N/A major point being for FI you want something like 8:1 and for NA you would want 10:1

i know mines higher than 10.1

if you were in vic i would let ya come in the car see how it behaves etc

but as tuffy said powerful NA needs to opposite to powerful FI

I have two engines one in the car and one im building up atm, Id set up the motor for FI thats coming out of the car to make way for my na build

so you saying depending on your mood of the day you might drop one motor in eg. FI and then change the motor agsin the next day coz you feel like NA?

;1241495']You cant have a Hi-po NA car set up for N/A major point being for FI you want something like 8:1 and for NA you would want 10:1

Correct there Paul.

No point building a NA engine with 10.5:1 or higher comp and then later decide to high boost it with a Turbo or supercharger as you'd wanna put lower comp forged slugs in it for that application (although if you did put say 10:1 comp forged pistons in a 6G74 engine but fitted 6G75 heads then this would lower the comp a fair amount due to the 3.8 heads have larger combustion chambers)

so you saying depending on your mood of the day you might drop one motor in eg. FI and then change the motor agsin the next day coz you feel like NA?

Easier have the Magna as the High output NA car and car like a EVO as a boosted toy :beer:

The above bloke is the one to listen to when it comes to an N/A build. I have been in his TH and it is a toey ****er. So anything he says to do then i suggest do it.

A bank cheque will be fine too. $50 should cover it. :happy:

so you saying depending on your mood of the day you might drop one motor in eg. FI and then change the motor agsin the next day coz you feel like NA?

No i was just thinking i may aswell do something with the motor thats coming out so why not slowly set it up for forced induction, Not so it can be changed on a day to day basis depending on my mood, I may sell the NA motor afterwards ??

Can i ask if you intend to convert to a manual trans? Seeing as your car is an auto.

Can i ask if you intend to convert to a manual trans? Seeing as your car is an auto.

Dave, hes already informed me that hes done a manual conversion. As a tough NA build would be a waste in a Auto magna

Dave, hes already informed me that hes done a manual conversion. As a tough NA build would be a waste in a Auto magna

can the auto box handle a tough NA build? not that its worthwhile at all

Dave, hes already informed me that hes done a manual conversion. As a tough NA build would be a waste in a Auto magna

Agreed. I just saw "auto" in his profile thats all.

can the auto box handle a tough NA build? not that its worthwhile at all

nup, it wouldnt idle

mine struggles to idle in manual form

can the auto box handle a tough NA build? not that its worthwhile at all

I reckon it could as the autos are already handling some good power and torque in boosted magna/veradas. I think the issue would be around town driveability with a high output NA engine in a auto magna/verada due to the relative lack of low down torque

nup, it wouldnt idle

mine struggles to idle in manual form

All my engines idle fine the main issue is they idle around 1200rpm and in a auto that would cause the car to lurch when put into gear ALSO remember that the torque convertor in a auto actually helps smooth out lumpy cams a reasonable amount... (well it does in my old school V8 ford that i have)

All my engines idle fine the main issue is they idle around 1200rpm and in a auto that would cause the car to lurch when put into gear ALSO remember that the torque convertor in a auto actually helps smooth out lumpy cams a reasonable amount... (well it does in my old school V8 ford that i have)

oh... mine idles quite low and would stall... around 800rpm

yeah i thought a manual conversion was a good first step in increasing performance, the ratios in the auto box were sooo long, made these bendy roads we have here in tassie boring

oh... mine idles quite low and would stall... around 800rpm

Thats why. We have my base idle set to 1100rpm and the idle up (when aircon is on set to 1300rpm) these have been set within the ECU. So on average it sits around those rpms give or take a hundred rpm. The car is running alot better now that ive swap over the TB blade to a better sealing one, this has helped stabilise idling as well.

Thats why. We have my base idle set to 1100rpm and the idle up (when aircon is on set to 1300rpm) these have been set within the ECU.

oh ok, i think might have been tuned before yours? so i guess steve has gotten better at the tunes as time has gone on

oh ok, i think might have been tuned before yours? so i guess steve has gotten better at the tunes as time has gone on

I asked him to set the base idle and idle up to those revs otherwise they wouldve still been at the lower settings (although my original TH ecu that was done by him back in early 2001 had the idle bumped up to 850rpm)

I asked him to set the base idle and idle up to those revs otherwise they wouldve still been at the lower settings (although my original TH ecu that was done by him back in early 2001 had the idle bumped up to 850rpm)

ah got ya.

would be interesting to compare cars if/when i come over to radelaide. Because i think the mods are reasonably similar

ah got ya.

would be interesting to compare cars if/when i come over to radelaide. Because i think the mods are reasonably similar

Chris got the engine built to the specs that i gave him, so yes the engine in your car is similar to my donkey engine.

Main differences are that my donkey engine has smaller cams (294* yours V's 270* mine) and mine doesnt have a 75mm TB, otherwise they are nearly twins :woot:

Any advice on cvs ? Any particular brand ? i managed to brake one last night and was stranded lol

Chris got the engine built to the specs that i gave him, so yes the engine in your car is similar to my donkey engine.

Main differences are that my donkey engine has smaller cams (294* yours V's 270* mine) and mine doesnt have a 75mm TB, otherwise they are nearly twins :woot:
i have no TB either, ditched it because i couldnt get it to idle properly with it ;)

Any advice on cvs ? Any particular brand ? i managed to brake one last night and was stranded lol

Im running stock MMAL ones in my car, im on my 3rd set over the 10+yrs ive owned the car. I had a few spare sets from my MMAL days....

Well i like them figures, i was getting clicking sounds after 2 months with repco brand ones

any idea how much they are from mitsubishi these days ?

Well i like them figures, i was getting clicking sounds after 2 months with repco brand ones

any idea how much they are from mitsubishi these days ?

No idea mate but knowing mitsubishi they wont be cheap and im not sure theyd have many in stock anymore

Ah yeah good point

Interested in what was being said about the 6G75 heads before.

Are they straight bolt-on and what are the benefits considering i would change the crank.

Interested in what was being said about the 6G75 heads before.

Are they straight bolt-on and what are the benefits considering i would change the crank.

Yes they bolt on but as they have a larger combustion chamber compared to the 6G74 heads they will lower the compression ratio on a 3.5L unless pistons are changed to something with less "bowl" volume.

Personally if your going to go to the trouble of fitting 3.8L heads and crank to a 3.5L block then you may as well go all the way and use a complete 3.8L engine as a starting point.

so the difference in CR (74 = 9:1, 75 = 10:1) is in the piston?

I did a bunch of calcs (trying to work out the CR on a stroked/bored 4.0L 74) and it came to less than 10:1 (something like 9.7:1 with the same combustion chamber and gasket size).

$1200 is a pretty good price for a new 75 crank. they retail around $1600 from Mitsu.

cheers,
.wook

How much do a complete 6G75 cost over there(Aussie)? Over here(US) they start off around $500USD ranging from 5000-90,000 miles.

ha ha mate id say they will be a little more than that in AUS. Im in NZ, and there was a 6G74 for $300 on trademe, almost got it just to have a spare!.