I'm reading up on 6g engines. I want to put one in a rwd chassis. I believe the 6g72 came In the 3000gt with dohc heads. I know they offered a 3.5L version too in some dodge vans, but those were sohc, I think. Do the heads interchange? Is there a go to combo with these engines? Also, were these really prone to blowing head gaskets? I read some of them made around 280hp (from an old NA 3.0 v6 from the 90's!).
There are a bunch of different 6Gs. As far as what you can easily find in the USA, there is the 3.0L sohc 12v 140-160hp, the 2.5/3.0/3.5/3.8/ sohc 24v 160-230hp, the 3.8L sohc 24v Mivec 270hp, and the 3.0/3.5 dohc 24v ranging from 220-320hp depending on whether its a twin turbo or na.
The DOHC are harder to find and don't have much advantage unless you plan to rev to 8k+ rpm. The Mivec never came RWD in the USA, but the other families did (although not every displacement, i.e. no 2.5 rwd but you could bolt one where a 3.0/3.5/3.8 was).
There's just a lot to say about them. I dont think ANY of them are unreliable other than the DOHC ones needing timing belts and bearing inspections more often than the rest. All the SOHC are very reliable imo.
What do you want it to do? Power level, rpm, in what chassis?
I think naturally aspirated and 300 hp would be good. I was thinking dual cam for the power band. Rear wheel drive configuration for sure. Oh and simplifying the engine as much as possible. That's why I would forgo turbos. I have seen with a 3000 GT vr4 Engine bay looks like. A mouse couldn't access some of those bolts!
do we know if any of the heads are non-interchangeable? Or whiteheads give a bump in compression? Is there a piston and rod combo or crank that can give a bump and stroke, bore, or compression?
edit: I'm having a hard time finding any forums that use these engines in a race configuration. There isn't much out there except some of the VR four guys that have trouble keeping them running.
The only rwd transmission that bolts to them is the 04-06 kia sorento manual trans. Good luck finding one though!
I do know a guy with a 6g72t starion with a th400 behind it. Bill Hincher made the adapter plate. Not sure Bill is still alive though.
There's rumors a ar5 trans with a montero bellhousing will work. But that's unproven so far.
In reply to yupididit :
I thought the d50 trans works? Or did it require an adapter?
There is a shop near me that specializes in 3000GTs. He sees plenty of broken ones, but they are all trying to make 600 HP. With a reasonable power level it should be super reliable, the bottom end is really stout.
Have you considered other V6s from other manufacturers or is this the one you already picked for other reasons?
Because there are newer V6s without turbos or direct injection that make 300 hp. Even with RWD and manual transmissions readily available.
Vajingo said:In reply to yupididit :
I thought the d50 trans works? Or did it require an adapter?
I haven't heard of that. Thought all d50's were mitsu 4g 4cyl
In reply to RossD :
Honestly a nissan vg or vq seems like the better option.
yupididit said:Vajingo said:In reply to yupididit :
I thought the d50 trans works? Or did it require an adapter?
I haven't heard of that. Thought all d50's were mitsu 4g 4cyl
Most of them were. The V6 was more common in the 4WD version.
I'd like to echo RossD's point. Unless brand loyalty is a big selling point of the 6G, a V6 and 6MT drivetrain out of a Camaro, Mustang or Nissan Z car seems like the play for a 300hp NA V6 and then you don't have to mess with adapter plates. If you want to mess with adapter plates Honda J series is cheap and plentiful.
Oh the lfx is a good and rather swappable v6. I gave up swapping a 6g in my Conquest and was going to do the lfx. Now I'm just trying to give the car away lol
No specially reason why it would HAVE to be a 6g. it's just an underdog engine and I thought it might be a cheap, fun, and different build compared to a "peel and stick" lfx or vq.
parts don't seem very prevalent where I live though...
I have a 6G73 2.5 V6 and there is NO aftermarket for it. Not much more for the 72. I have one of those in an Eclipse that I was going to swap into the Avenger but looking at aftermarket, I may change my mind. These things are almost 20 years old now. There was a guy who was supposed to be THE 6G72 guru on another site, but when I started asking questions about the reasons for doing some of the things he suggested he just disappeared. I like to know why and what the expected outcome should be. I did find a link on allpar.com that had some useful info.
https://www.allpar.com/mopar/3up.html
https://www.allpar.com/mopar/3.html
and then there is this. gez wrote: "The biggest problem in working with the 3.0 is trying to work around the factory computer, which retards the timing after 15 sec of full throttle with the automatic and immediately with the stick. "
drock25too said:and then there is this. gez wrote: "The biggest problem in working with the 3.0 is trying to work around the factory computer, which retards the timing after 15 sec of full throttle with the automatic and immediately with the stick. "
Luckily things like MegaSquirt exist because then you can effectively tune things to avoid some of that. Assuming the engine can handle those settings.
Like nearly any 4-stroke engine there's a pretty standard list of things you can do to make them "better"
More air through the engine via effective porting of the heads, 3-angle valve jobs, increased compression ratios, altered valve ramps via cam grinds, tuned to help pull exhaust gasses out of the cylinder, extra displacement by moving from a 2.5 to a 3.0 or even a 3.8 if you want more low end torque instead of high RPM power.
More RPM via lightening rotating pieces. So lightweight rods and pistons, knife edged crank, crank scraper, lightweight cam gears, lightened flywheel, cams and related pieces, stiffer valve springs.
Extra cooling via oil cooling and larger and/or more efficient radiators. Possible rerouting of coolant through the engine to cool the heads first, etc.
Exotic intake solutions like ITBs or dual plenums, dual turbo or super chargers, etc.
There are factory RWD manuals and automatics for the 6g. The manuals are rare and mostly 4wd (although a transfer case with no front driveshaft and no shifter is a heck of a lot easier to ignore than lots of other swap issues), but they're out there. The autos are basically the same Aisin 4spd auto found in all kinds of other stuff like at least one Supra running an 8 second 1/4 mile. I had one in a Cherokee with 358k miles on it. Great, simple trans that requires almost no wiring.
As far as a 300hp v6 with no turbos, you're in luck! Mitsu made that. It's a Mivec 3.8. They don't make 300hp from the factory but basically all of them that have ever been modified in any way do. Like, intake, muffler, 300hp. The stuff you'd be improving in the course of a swap anyway.
The DOHC heads really don't have any advantage over the SOHC heads unless you're planning to independently mess with the timing of each cam or trying to make WAAAAY more than 300hp na, in which case the big-port dohc heads MIGHT be worth it. Maybe.
Even the 3.8 Mivec heads are not really special other than being Mivec. As in, if you took the regular 24v sohc heads and put an equivalent cam to what the Mivec is doing at high rpm, it would make similar power. The Mivec is just allowing it to be mild-mannered at low rpm. This is the same thing with like 1990s Neons and Hondas. The Hondas got all this reputation from making big high rpm power. If you put equivalent cam/manifolds on a Neon it would do basically the same thing, but without the variable valvetrain system it would have all the normal downsides of putting an 8500 rpm cam into a small engine and then trying to drive it at part throttle (good luck). So really the Mivec system is just allowing the system to use a 'bigger cam' while retaining normal low rpm drivability. All the 300hp v6s do this, and as you alluded to Mitsubishi was one of the first with their 3.0L from the 90s bumping into the 'gentlemans agreement' ~276hp rating or whatever it was. But pretty much any of the 24v 6g heads have the flow to make the power if you want to put bigger cams in them.
In fact, that's one of the reasons why the 2.5L 6g that Drock mentioned was such a flop (I had a 2.5L Avenger too). It has head ports for like 8500 rpm but only 2.5L worth of low speed port velocity with a tiny plenum and cams and a 6500rpm rev limiter. It's a mismatched motor and doesn't really work properly. But the same heads on the bigger displacement versions can (with bigger cams) have their good headflow utilized in a more realistic rpm range. It's just that so few people do aftermarket cams on these engines that the headflow is not acknowledged by Joe Internet talking about what's a good v6. Which is fine. Either use the Mivec or settle for less power from a stock-cam non-mivec. The highest non-mivec rating i'm aware of was ~250hp from the Magna Ralliart which was a 3.5L 24v sohc with minor changes, same stuff you'd improve during a swap.
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