Bigger is better?
Well no , not really....more revs is better (motorbikes and formula 1) but once you've got more revs, more CCs is an improvement for turbo spool.

There's more than one way to do everything, there's no direct drop in solution, not unless your car is FWD.


Yes, a 6G74 block can be made to work but pretty much everything on the outside needs to be modified to fit, for my own car , it might not even fit under the new bonnet as it's a bit tight as it is.

Putting a 6G74 crank into a 6G72 block is an option, maybe not ideal. Instead of modifying everything on the outside, it's the inside that needs modifying

An interesting read here, not without the usual piles of misinformation of course.
http://www.3si.org/forum/f1/best-engine ... 74-470445/

There's been a billet stroker crank on the market for years, 3sx sell it.
http://www.3sx.com/store/comersus_viewI ... duct=28777
It's only US $5329 and is a drop in at about 3.4 litres from a 84? mm stroke. Actually, it's NOT a drop in, the block still needs clearancing.

The Ebay option
http://www.ebay.com/itm/Brian-Crower-St ... 1147637091 at approx $NZ 7817.28 before GST.

Otherwise there's the pampena option
http://www.pampenamotorsports.com/pampe ... 3-5-liter/

at US $5249 but needs lots of work and exchange block/crank.

If you actually read through the Pampena specs very carefully....nowhere does it mention that the crank is nitrided afterwards. All steel factory cranks, that's pretty much every crank in every jap car, they've got induction hardened journals, when you cut them down over 1mm you go through the hardening so they need nitriding afterwards to re harden them...otherwise they wear out quickly due to being too soft.

OK, so what do you really get for your US $5249.
The block needs a bit of grinding to clear the crank.
The crank needs cutting down to 6G72 journal sizes from 64mm mains to 60mm and from 55mm big ends to 50mm.
The Pampena stroker uses stock (stock length but aftermarket) rods but custom shorter pistons as does the BC stroker.

6G74 pistons are shorter too, more so if you use the right ones, there's several different ones.

If you destroke the 6G74 crank a bit, say to 84mm like the BC stroker then it's a bit easier.


The 1st pic, that's a moving blurred pic of the crank in the grinding machine cutting down the counterweights a bit.
http://www.iforce.co.nz/View.aspx?i=xwmzsm5i.qqr.jpg


Here the mains have been cut down from 64mm to 63mm so it fits in the block without bearings (the bearings make 3mm diameter)
http://www.iforce.co.nz/View.aspx?i=qacr25xn.amz.jpg

The block needs grinding in various places to clear, either side of each main bearing and a bit at the ends where the biggest counterweights are.
http://www.iforce.co.nz/View.aspx?i=pdgo0c4v.two.jpg

Similar to above.
http://www.iforce.co.nz/View.aspx?i=oi23l05n.crp.jpg

Again, similar
http://www.iforce.co.nz/View.aspx?i=nes2zrmn.gtb.jpg

Then some U tube.

Once the crank clears the block and turns without catching anywhere, the girdle then needs grinding too to clear.

https://www.youtube.com/watch?v=AKzd-VGAQuk

and

https://www.youtube.com/watch?v=7eiNxAf--1E


Work in progress...like all projects.
As with my other junkyard projects, the aim is for it to end up costing me as close to nothing as possible.
Unfortunately it will cost me to get the crank nitrided afterwards......pretty essential, it will also need balancing which " might" cost me...maybe?


The block I'm using is the original one out of the car.
The crank is a spare, originally out of a GDI Pajero which had spun a big end bearing, munched up the crank, had to be taken down to 0.75mm undersize but for some reason the bearings wouldn't fit........so the pajero ended up getting a different crank, one of my GOOD spares.
All the other bits, they're just leftovers.
The pistons are from an ozzy built 3.5 SOHC , they're low compression, built to run on 91.
The block will be bored out to 93mm to make them fit, it's already out to 91.5 or 92mm as it's been rebuilt with oversized forged pistons in the past......blew up due to a failed built by someone else about 14 or so years ago.

http://www.iforce.co.nz/View.aspx?i=q34lfypo.axd.jpg
That's about where I'm at now.
The no6 bigend has been cut down to 53mm so that the rod bolts up without a bearing. That's before it was destroked by 2mm which gives 1mm extra clearance to both the bottom of the piston and at the same time reduces piston protrusion out of the block at TDC by 1mm.
I adjusted the crank grinder so that it's axis is on the bigends (no6 bigend) which allowed me to take off the high spots from the counterweights, that's for no 6 piston clearance....if that makes any sense?

So...if you look at the bottom right hand corner of the pic, the curve on the counterweight was trimmed with the crank spinning on the same axis as the main bearings......where the curve changes close to where the conrod is, the counterweight was trimmed with the crank spinning on the axis of the big end bearing...........easy as?

another vid

https://www.youtube.com/watch?v=e9ffbeu ... e=youtu.be

Steve

Latest vid.
https://www.youtube.com/watch?v=N1H4xvkOGI4

Steve

I've been plodding away at this without rushing.
No point in rushing because it'll end up getting done wrong and will need doing again but properly.
I've changed plans slightly and decided to use the JE pistons ( a bit less than 93mm) I've had sitting around for a while.That means I should really use the Pauter rods too which are sitting an another unused block.
3 reasons.
1/ I've already got them.
2/ I can use the low comp 6G74 pistons in a 6G74 block.
3/ The top ring sits further down the piston and I've already machined the top off one of the pistons for a test fit.......lols.

The crankshaft........it needs to be nitrided. Just the same as it needs to be balanced.
If it's not nitrided it's effing useless and won't last.
Steel on it's own is too soft for a bearing surface.
The factory cranks have been induction hardened but that's only the surface. I've ground through it.
When a crank has spun a big end bearing, they always bend..........ever so slightly...........in the mains adjacent to the big end that spun
That on it's own is never a problem because the normal way of fixing it is to grind it straight.
The crank I'm using started off like this.....with a spun bearing and was ground straight.
The problem here is that in order to nitride the crank, it gets put in an oven in an atmosphere of nitrogen at high temp for a period of time. Sometimes they come out bent.
The normal procedure here is that you send away the crank, it gets left in the oven for a while in order to de-stress it, it bends...... you then grind it straight, get it down close to final size, then send it back to be nitrided, where it should come back straight.
Me being cheap and lazy and don't want to send it away twice.......I put the crank into my log burner for a week.
It came out bent which is what I was hoping for.
Bent as in about 15/100mm which is about .006 inch.
It's now been ground straight and is just over final size.
No point in rushing things?....funnily enough, the crank is no longer nice and shiney but looks like it's been in a fire.

http://www.efunda.com/processes/heat_tr ... ieving.cfm

https://www.google.co.nz/url?sa=t&rct=j ... 4247,d.dGY

In the meantime I've been tidying up my garage and found a few long lost parts.


The 3.8 block I've been sitting on (from a 380), there's no provision for engine mounts to fit it into a GTO so that will end up as a RWD project with mivec and more than 2 turbos.
I've got a couple of 3.5 pajero blocks, I've dummy assembled one with N/A heads (no mivec) which I'll build to go into a GTO.
There's the diamante based 3.5 with mivec which just needs a couple of minor problems fixing then that'll fit a GTO too.

Steve

Update, I found some used main bearings for a trial fit, that's with everything cut down to 6G72 sizes. There's a bit more girdle grinding to do. The thrust washers were a bit tight, had to take a couple of thousandths off the sides to get them in.
I'm sure someone on an american forum tried to make out like there was a difference in bearing widths between '72 and '74........but they've always been the same, still are.
I nearly forgot where I got to?
Making a jig for 60 deg V6 blocks so that they'll go on a surface grinder and also on a overhead hone, just to make other things a bit easier.
That's next month.

In the meantime I found this
https://www.youtube.com/watch?v=p1BNNeZn3FE
I don't need a fluid flywheel/ torque converter as a brake because I've got a heavy flywheel but some sort of brake as an add on would be handy for holding the revs while on full throttle.
That's another project yet to come.

Steve

I've now got a full set of 6 conrods ready to use, modified stock ones.
I had a good set of 5 , no 6 broke a few years ago.The original 5 had all been balanced by someone else a few years back, as in small ends balanced, big ends balanced, total weight balanced. They'd also been converted to fully floating pins.

I got a bit held up because I've got other things going on too and needed to repair the motor on my lathe before I could use it.
With no 6 conrod, it's just a spare which had a broken piston attached, got lots and lots of spares. I pressed out the pin, honed the small end on the lathe to make the pin fully floating, weighed all the rods and ground no 6 so it's the same as all the others. There's only about 1 gram difference between heaviest and lightest.

I've had a couple of slight changes in plan, nothing major.
Instead of using the 6G74 Diamante SOHC pistons, I'm saving those for a 6G74 block. I'm using some JE forged pistons I've had for a while, they'll fit and may as well use them because they're no good for anything else.
I had to buy a new digital caliper, the old one died when it got water in it.

Sizes get very confusing dealing with aftermarket yank parts built in inches when jap engines are in mm.
Stock bore is 91.1mm. A stock piston is about 91.05mm or slightly bigger to give the correct clearance. The first American oversize is usually 10 thousandths inch or .254mm. My block actually measures 91.35mm because it's already been bored oversize and run with Ross pistons.
The JE pistons measure about 91.5mm so with about 4 thou inch clearance, the block will need to go out to about 91.6mm, more accurate measurements come later using better tools, as in micrometer and bore gauge instead of china caliper.

As I mentioned on another thread, when you buy forged pistons you expect them to be better all round than stock ones. Better as in stronger.
Unfortunately the truth never works out like that.
The pins in every brand (JE, Ross, Wisco) of forged piston are thinner, lighter and weaker than the stock pins........so into the scrap bin with them.
Stock gudgeon pins FTW.
I've also torqued all the caps or the conrods to make sure that they're round still, which they are, within spec anyway.


Next job, bore and hone the block.......maybe?
When I get around to it?

Doing some quick maths on the size it'll work out at 3321cc, so a bit short of 3.4 but nevermind, it'll get mivec of course.......no point in building anything without it. It's still an extra 10% capacity for pretty much zero cost from otherwise junk parts.

There's no point in boring any block out to the max because what happens is either the bore cracks or you'll get a pinhole in the bore which then fills with coolant, I've seen it a few times. Sleeving is the way to go but it's very time consuming. Over boring a block also causes bad ring seal and excessive blowby because metal acts like rubber when it's under a lot of stress.

Like here.

http://oldjohnno.id.au/page5x.html

Same goes for going all crazy porting your heads.......it's a complete waste of time and money but we'll get onto that later, all the gains with head work are at the valve and seat but you can't do that at home and show it off on facetube.

I've finally figured out what I'm doing wrong.

https://www.youtube.com/watch?v=bT1nRq-cM7M

Barry

magn1t wrote:

I've finally figured out what I'm doing wrong.

https://www.youtube.com/watch?v=bT1nRq-cM7M

Barry

Hahaha don't go too fast and warp the block!

Ha!

Where'd I get to with this?
Checked the final journal sizes on the crank.
Found a good set of used main bearings, as in no marks on them.
Fitted those.
The crank turns in the block with no girdle on.
Found some used thrust washers, they never wear out anyway.
Bolt on the cradle......a bit too tight.

The problem here is that the 6G72 uses 4 small thrust washers, the 6G74 uses 2 large ones.The crank actually needs widening just a bit at the thrust face.
Pull it to bits again, widen the crank at the thrust washers, re assemble, measure thrust clearance......0.05mm which is the minimum spec (0.05 to 0.25mm).

There's a spot on the girdle where it binds(right in one corner) so ground that, fixed.

I've also found a good set of used big end bearings, test fitted one conrod with a stock piston, moved along the crank to check for clearance, found one more spot under a bore which I missed, ground that.......now it all rotates freely. That's with mains and thrusts in place.

Ready for boring now.

https://youtu.be/gPOWbkDZNXA

Meanwhile over in the Barryboys workshop........



That's a crank from a 30M which i bought a few years back.
It spun the no4 rod bearing, cracked the crank, you can just make out the horizontal line. So it's junk.
But the heads are mint.



I've also been dummy assembling my 6G75, see how much I can decompress it by.....for free.


Lucky I keep all my old head gaskets. 4.4 mm now. Uncompressed.Got to put heads on, see what won't fit.

I've decided it's too hard to make that block fit in a GTO, not that it matters. It's going to get assembled like a Pajero for RWD.
The sump needs a cut & tuck.

There's a 3.5 DOHC Pajero engine sitting in a hole right now....just for a few measurements.



The sump is sitting on the cross member so after surgery should sit 4 inches lower.
There's lots of space for lots of turbos.


Here's the 3.8 with the 30M heads on and timed up with a 265T belt.


The lower intake manifold fits as does the coolant crossover above the flywheel, both a bit tight due to the headgasket thickness.

I thought I'd better go over the HG thickness again....it's an extra 1.5 mm each side.
I've got the original 6G75 gaskets on, 0.40mm ish.Then a 6G74 at 0.30 ish mm, then 3 6G72 HGs at 0.40 ish mm each.
That makes 1.9mm in total for each side. The '72 gaskets I'm using are from 30Ms
For comparison the 6G72 N/A / TT HGs are 1.4 to 1.5mm but the pistons stick out of the block at TDC by about 0.5mm. That should give about 1mm piston to head clearance.
With the 6G75M the pistons have a very slight dome but otherwise sit flush with the top of the deck at TDC. That means I should have about 1.9 ish mm piston to head clearance. There's no valve reliefs in these pistons.......it turns over by hand OK but it does feel like there's tight spots........need to check piston to valve clearance. Then re shape the pistons a bit in the lathe.

The back end





Barry

OK so from barryboys.


4 intercoolers..............beat that.?


Don't need to.

I'll raise you 10 head gaskets?

Beat that?
Hahaha lol

By MEEEEEEEE

Well.................that's what it' s all about.
I read ages ago 6G75..............carribean somewhere?.........Puerto rico?
30M heads on '75 block & pistons
The valves will hit the pistons and bend .
DNF?
No, DNS.



The world's full of ricers.......they'll believe anything?
10 headgaskets............beat that ?

what concerns me in doing this same thing is the bore is around 4mm bigger on the 75?
are you planning on machining out the head to match?

Scruffy wrote:

what concerns me in doing this same thing is the bore is around 4mm bigger on the 75?
are you planning on machining out the head to match?

Hopefully the size of the combustion chamber will be just about OK for the 75 bore. 4mm bigger is only really 2mm all the way around..
Got to remember that Mitsubishi actually built one or two "Paris Dakar" Pajero evos which were 4 litres.
Originally they were 3.5 which is just a standard 6G74 mivec.......there's no info on the 4 litre but apparently with rule changes, you could only make them bigger if you added a minimum of 500cc. That ruled out the 6G75 at 3.8, so had to go to 4 litres.
No idea on the bore and stroke but an overbored 3.8 would be the easy cheap way for them to do it instead of a special crank.
It must have worked? Nor can I see them making special heads.

interesting stuff.
another concern, if youre running any smaller gasket than the 75 bore, you run the risk of the edge of the gasket becoming a dangerous hot-spot?
in relation to the previous question, i suppose youve almost extended the combustion chamber to the 75 bore in increments - stepping through the gasket sizes haha

Yes, that's right.

If you read up on the yank forums.........a '74 block........they recommend champhering the pistons to use a 72 gasket.
But why when you can use a 74 gasket?

Going over it again......the head seals to the gasket.
The block also seals to the gasket.

A '75 gasket might be 95.5mm?
A '74 gasket might be 93.5mm?
A '72 gasket might be 92mm well it depends on who makes it?


So building them up and stacking / stepping them isn't great but can't be anything worse than what the "gurus" recommend?

At the moment my main concern is that turning it over by hand there seems to be 3 tight spots.
Because I've stacked the HGs, there's quite a bit of cam timing error on the front bank, that will drag me back into the "degreeing cams" thread.
With the 30M heads, you can screw a small bolt into the mivec plungers . pull on that and you get mivec at rest.That's how you degree the cams and measure both more lift as well as more duration and more piston to valve contact.....so more measuring to do.

Plus for cheap/ free isn't too bad?

If it works then it works and if it doesn't .....then so what?
The only thing really to go wrong would be pre ignition from a hotspot caused by the gasket ?
So...need instruments to check it out?
Plus the CR which is still going to be too high?


edit, so the CR?

A 30M is 495cc per cylinder, officially 10 to 1 CR. The pistons don't stick out of the top of the block at TDC like N/A / TT and they're pretty much flat top.
Divide the 495 by 9 to get 55cc for the total vol of the combustion chamber.The piston is flat, so there 's just the headgasket at 0.4mm and 92mm.That should be 2.6cc leaving 52.4cc for the head.
Then putting that head onto a 3.8 with flat top pistons, HGs at 0.4 x 94, 0.3 at 94, 0.4 at 92 by three making 1.9mm........about 13cc.
694cc per cylinder.
That works out at about 11.6.


OK so what if you just used the 1 HG at 2.6cc?
That's 55 + 694 / 55
13.6.
Yes I can thin the pistons out a bit.
I can add more HGs and slot the bolt holes in the lower intake and coolant crossover?
Then mod the cam gears.

There's a 30M head showing how the headgasket fits to it's size. Straight off a dead engine.



Another 30M head but with a 6G74 headgasket over the top showing the difference. The HG is 94mm, it's just loose and not centred


H G thickness.



That fitting on the front of the head.......that's the Pajero thing....it lets the bubbles out from the highest point...otherwise they keep cooking and destroy heads. I've got to mod it to make it fit.


The 6G72 block with the 74 crank which I started this topic with, that's in a queue to get bored out so it's just on hold for a while, then it'll be back.

I'm also trying to finish off one or 2 problems getting this together.

why dont you take out the "3 6G72 HGs at 0.40 ish mm each"
and install one "6G72 N/A / TT HGs are 1.4 to 1.5mm"
give a little more clearance and cut out a few unnecessary seals and potential hot-spots?

Scruffy wrote:

why dont you take out the "3 6G72 HGs at 0.40 ish mm each"
and install one "6G72 N/A / TT HGs are 1.4 to 1.5mm"
give a little more clearance and cut out a few unnecessary seals and potential hot-spots?

Yes, it's one of several options.
The difference is that the thin HGs are all metal shim gaskets, the thicker ones are composite gaskets.
Where I'm at now with the stacked HGs, any more height and the bolt holes for water crossover and lower intake, they'll need slotting or the parts won't fit.
The cam gears will need adjusting too. So maybe at the moment I'll look into trimming a bit off the piston tops then probably do some real measurements for volume.....then come up with a plan.


I've been sorting out my parts, got far too many of them, it's hard to do anything in a mess.
The easiest way is to start putting things together which I've been doing for some time now, it all takes up less space that way.
By that I mean find the correct bolts which go into the holes, find all the brackets, bolt them together loosely , see what's missing and see what's left over.




I moved them all out of the garage to move the furniture around a bit, generally make more room.




From L to R there's a Diamante 30M engine , pretty much complete which I've swapped the brackets to GTO, cut the sump etc, all the hard work is done...it'll drop into a GTO.
Then the 3.5 from the SOHC Diamante wearing 30M heads etc, nearly complete......both of these, just got to decide how and where to remotely mount the oil filter.
On the next right, there's the 3.8 out of an ozzy 380 with 30M heads, going to be RWD, that's the one where I've stacked the gaskets. Got to adapt a RWD gearbox to it
Right again is my old forged 4 bolt 6G72 with N/A heads sitting on it for now......I'm tempted to get rid of it?
Far right on the frame with wheels, that's the basis for the engine dyno, at least to start with, it's just an N/A block, TT heads with a pair of 15Gs bolted up.
The one sitting loose in the engine compartment, that's an untouched 3.5 DOHC Pajero engine.
What's left over is the 72 block with 74 crank, a bare 74 pajero block and a bare 30M block, lots of 30M bottom end parts.

There's no rush to put anything together because my GTOs work and have good engines in them.

Barry

I've been on the hunt for a spare 3.0 short block for a while. Keen to get rid of that 4 bolt?

PM me. Everything is for sale if the price is right.

Barry

I wonder how the modified sump on the 30M engine handles on a track? The stock GTO one isn't up to it with good tyres.

I think the idea when going on the track is to run it with an extra litre of oil in it.
Having too much oil is always better than too little.
When's the last time you heard of someone having problems with too much oil?
Yes, doing a cut and tuck on a sump means less capacity BUT you can make it deeper at the same time to compensate.
GTO sumps are actually a bit deeper than the others. It's just a case of modifying the pickup at the same time which is no harder than doing exhaust pipe.

Barry