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chucknasty
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558 Posts
im thinking about picking up a 272 cam from rpw, when i rebuild the engine.
as far as i know the 4g69 head is still the same as the 4g64 just with mivec which sucks. i know of a dohc swap for the 4g64 that really opens it up (bigger ports, uses evo 8 manifold, comes with 60mm throttle body, uses evo 8 cams) but you would lose mivec with that setup.
 

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resident crossplatformer
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1,430 Posts
That could easily be a JDM 6g74 (which has DOHC), has the pretty much the same block (, external and internal dimensions as) the incarnations of the 6g75 minus some small changes to the casting
Although it wouldn't surprise me if somebody had both the top ends of a DOHC 6g72 (or DOHC 6g74) and a regular 6g74 (or a 6g75), and then decided to see if the DOHC heads would mate up, which they do, also 6g75 (both versions) mate up to a 6g72 just fine
 

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chucknasty
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558 Posts
if you do 6g74 or 72 heads on the either 75 you would have a much higher compression ratio due to smaller combustion chambers. not to mention smaller valves, ports, etc... why would you downgrade? best non mivec heads right now are the 6g75 non mivec, best mivec heads in the 6g series are the 6g75 mivec. the only one in the 6g series that might be better are the GDI 6g74 but those would never work anyways.
 

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resident crossplatformer
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1,430 Posts
nice, never heard of the 6g74. can that be directly swapped in?
yes, but it is a much less advanced engine, it's 3.5 liters vs th 3.8 liters 6g75 is, smaller bore (93 mm irrc), smaller stroker (85.8 mm), much poorer flowing heads and intake manifolds, but the connecting rods are much, much stronger (than the 6g75 rods) however are heavier, if you have a dead engine block (and want something beyond a stock motor) and your crank is fine, buy one of these engines and use the rods and block for the rebuild
you can pull one out of a second gen Diamante
if you do 6g74 or 72 heads on the either 75 you would have a much higher compression ratio due to smaller combustion chambers. not to mention smaller valves, ports, etc... why would you downgrade? best non mivec heads right now are the 6g75 non mivec, best mivec heads in the 6g series are the 6g75 mivec. the only one in the 6g series that might be better are the GDI 6g74 but those would never work anyways.
FYI for the future
6g74 and 6g72 (SOHC 24 valve versions of both) use the same cylinder heads, down to the casting (but the 6g74 block is much taller), just use different cams, I can't say the same for the DOHC heads of either engine as the DOHC 6g72 has different head castings for the TT version

and exactly, what's the point? why use a worse flowing head? this is literally the reason why it is not reccomended to ever procede to build a SOHC 24 valve 6g72, that and expanding the diplacement over 3.1 liters gets expensive

I can't say if the GDI 6g74 heads would be better (there is a MIVEC GDI DOHC 6g74 version, but those are even rarer overseas than either just the DOHC MIVEC and the GDI heads (which are DOHC)), I'm going to just guess that they aren't, but it would be a hell of a novelty to be able to use them, also it is worth noting that these engines have been in existance irrc since 1997, just food for thought
 

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The Evil Wizard
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378 Posts
DOHC heads on a 6G75, yes but you better off with the 6G72 Mivec DOHC heads. Ralliart still ran the MIVEC DOHC heads in the Dakar races till moving on to a diesel engine. The Mivec SOHC is known to flow more CFM than a full race ported DOHC head but no one has bench flow a Mivec DOHC head. But one thing can be say about the DOHC Mivec heads is than the cam profiles are much bigger than the SOHC Mivec ones.

The only problem running the Mivec DOHC heads or any DOHC heads is mounting the Eclipse CAS.
 

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resident crossplatformer
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1,430 Posts
also for the MIVEC DOHC heads, from what I have seen in the repair manuals, they also use the split cam journal design so the lobe lift would not be limited to the cam journal diameter if giant cams are used
I agree, we do need to find out the flow characteristics for the MIVEC DOHC heads, I am also curious on the GDI heads characteristics too, ports are vertical too...
 

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Registered
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4 Posts
actually no, bolt pattern never changed in the engine family

exactly, and this is why a buddy of mine is building my 6g75 in exchange for a set of NON-MIVEC heads, it has been noted from Ray Pampena (the guy you can send your 6g75 in with 10 grand and get it back displacing at least 4.2 liters) that the 6g75 intake ports are some of the best designed out there

to settle this, why would you want the 6g7 DOHC heads? Outside the fact they flow poorer (or nearly the same) in race spec performance porting with bigger valves compared to the stock 6g75 none MIVEC heads, as is brought up, there is the issue of how to control the engine with them (well, if you don't have to worry about smog, a 1999 3000gt ECU reflashed or a standalone will do), and also using these heads alone for performance just parts wise due to, well, there are 4 cams, 4 cam gears, will be twice as expensive
one thing I should point out, a timing belt or tensioner pats won't be too difficult if they are used in the tall deck 6g7 engines (6g74's and 6g75's), you can order these parts from Rock Auto if you dig a little
How can I get ahold of Ray Pampena? www.pampenamotorsports.com website didn't work.
 

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Basically Stock
2009 GS Turbo. 2007 Mid Engine GT
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7,045 Posts
I have the 6B31 3.0L SOHC with 4wd Automatic.
Would love to retain the 4wd Auto!
Ah, a newer outlander than the 6G/4G series. I can't speak much about those ones. You'll be changing your transmission to one from an Endeavor if you want auto and AWD with a 6G75 most probably. Else, I speculate you'll have to look into making a bellhousing adapter. 6B series are not something I play with, but 400hp isn't a crazy high goal. A single rear mount turbo and stock motor would likely get you there. Supporting mods, I can't say what you need. But it's low boost so likely stock internals at least
 

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resident crossplatformer
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1,430 Posts
I have the 6B31 3.0L SOHC with 4wd Automatic.
Would love to retain the 4wd Auto!
I've seen pictures pictures of the bottom end of that engine, it looks strong (keyword, looks) and there is somebody in Russia who has turbocharged such an engine and drive train, but I cannot say what else was applied to the engine (rods, pistons, bearings, main studs....) or the transmission
 

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4 Posts
Yeah I think I've seen that guy. I'm almost at 200k kms so I'm looking at 6G75 crate engines that are built for turbos so I'm just wondering what else has to be done to make it work? Crate engines are cheaper then rebuilding or buying a new stock engine. Endeavour 4wd transmission?
 

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resident crossplatformer
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1,430 Posts
Yeah I think I've seen that guy. I'm almost at 200k kms so I'm looking at 6G75 crate engines that are built for turbos so I'm just wondering what else has to be done to make it work? Crate engines are cheaper then rebuilding or buying a new stock engine. Endeavour 4wd transmission?
Where did you find a crate 6g75? Do you mean remanufatured? There is also the question of engine control and engine mounts
 
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