Hey turbo engine experts.. got a few minutes? (dsm warning)

[dodgeshadowchik]

This article was written some time back about the 'ol "crankwalk" theory on the 4g63 2g 7-bolt. Granted, I don't really think it was as big of a problem as it was made out to be, but this is an interesting theory. Now currently I have a few of these blocks laying around; all of which need some type of machine work done. I was considering blocking these squirters off after doing some reading about them and how they can get clogged or bleed down, ect. However, I know that their purpose is to cool the piston/rod. "They" say that if you go with a good set of forged pistons that there will be no issues with not having them. Just curious as to what other people's thoughts are on this. Apparently they have run a few race-built engines with no issues.

http://magnusmotorsports.com/?page_id=323

[roachjuice]

Dsm=fail

[dodgeshadowchik]

yeah, yeah.

too bad that can be said for just about any car that has had a following of moronic kids and hacks.

[TurboJerry]

I'm no engine expert but I recommend running the squirters because the pistons get very hot in a turbo engine that gets driven more then a 1/4 mile at a time. Lack of oil changes/extreme oil temp will allow the oil to coke up the squirters. (not *usually* a problem with synthetic oil) As for the dreaded crank walk I've drilled a 1/16" hole thru the main web where the oil hole is that feeds the bearing & thru the thrust surface of the bearing facing the flywheel side of the block. Big block chevys had the same problem & that's where I got the ideal from... Hope this helps !

[iTurbo]

I had a TIII with major crankwalk. It was so bad the crank had to be replaced, but the block was OK. I got the block off of eBay so I don't know how it happened; I always assumed it had some mondo pressure plate that wore out the thrust surface on the #3 main. Replaced crank with 2.5L after reading about Cliff R's Aries wagon.

[Directconnection]

yeah, yeah.

too bad that can be said for just about any car that has had a following of moronic kids and hacks.

True, but even moreso for mornic TM owners.... hehehe

I'm no engine expert

What?! That's news to me (btw: how's it goin' Jerry?)

One thing people fail to recognize is that ANY engine that gets beat on a regular basis and is making more HP than stock needs to get rebuilt every so often (race engines = every season) This means NEW rings and bearings....

I think if that Shepard guy can run in the 8s, then he's got crankwalk all figured out

[Juggy]

I had a TIII with major crankwalk. It was so bad the crank had to be replaced, but the block was OK. I got the block off of eBay so I don't know how it happened; I always assumed it had some mondo pressure plate that wore out the thrust surface on the #3 main. Replaced crank with 2.5L after reading about Cliff R's Aries wagon.

hey do u happen to know the link to that article?? i was trying to find it a week or so ago. alls i remember was that the car picked up like 40 wheel tq and not a loss of HP. I got a 2.5L lotus too

[dodgeshadowchik]

That's true about the more HP part; but these people claim to have seen premature failures on stock engines. Shep runs a 6-bolt... the oil squirters are fed from the main oil galley; whereas on the 2g they are fed from the main journals. So the thought is the location was part of the problem.

Thank you for the input thus far.

[iTurbo]

Unfortunately Cliff's site went down some time ago. I also heard he sold the car and is back to 2.2L because they couldn't keep a head gasket in it. I'm hoping for the best for my 2.5L TIII.....not making a bunch of HP like Cliff was, just want to make my SL fun again! Honestly I will probably just use stock head gasket and maybe ARP studs.

[Directconnection]

I actually read the article this time around....

The guy has some valid points.... but I am not sold that the "stuck open" squirters are the culprit, causing loos of oil pressure/flow at the main bearing/thrust. I am sure it makes a difference, but not so sure it's enough of a difference that he's seeing those problems. But every band-aid fix will add up and help...

["Top Fuel" Bender]

[roachjuice]

That's al I got.

[ShadowFromHell]

I had a non-cb T2 motor that developed crank walk... destroyed the thrust surfance on one side of the crank. Had a t2/t3 clutch and got beat on alot. The machine shop I took it to, to see if it could be fixed years ago told me the first machine that turned it could have messed it up when the turned it, or I could have been twisting the block but its almost impossible to tell.

As for your oil squirters, I would try to find a way to keep them. But if it will fix the crank walk, and its not going to be going into a real high HP car maybe you could get away with it?

[zin]

Bottom line on the squirters is that they are there to cool the pistons as has been mentioned. Replacing cast for forged is always a step up, even they loose much of their strength at elevated temperatures. A cooler running piston is a stronger piston, so I'd keep or even add them to an engine, but you do need to ensure the oiling system can maintain 10PSI of pressure for every 1000RPM.

Mike

[dodgeshadowchik]

Thanks for the suggestions. That's kind of why I was on the fence about it. Magnus builds race engines; not daily drivers. This could be fine for that application, but maybe not so much for a daily driver. They also use N/A blocks (which do not have squirters) but once again; racing purposes. Sure a good forged piston could probably handle the extra heat; but what if it can't.. then I'm out the 400-500$ for pistons. lol..

I guess what I'm trying to do here is build something that is done right and reasonable. All three of the engines I have do not show signs of the dreaded "walking crank" but sometimes I'll come across some interesting articles like the one above and it makes me stop and think. Mitsu also DID change the thrust bearing design in 1998. I was thinking of using that bearing; if possible.. since this so called problem seemed to have disapeared in 98 and into the EVO platform.

There's just been so much hacked and slashed on this car it's really sad. I'd rather see someone body kit a car up then mess with the suspension and drivetrain components.


Oh yeah.. in response to the one image above: never had a trans problem with the car. Until about 197,000k. CLUTCH problems; well that's another story.... then again this is more of a manufacturer problem than a car problem. A stock 215HP car shouldn't be able to break fingers like this:


NEver will use another ACT clutch again.

[rich tideswell]

ok i need a dsmucation - are you talking about the squirters that are in the pistion where the rings are, or does this beast have extra squiteres in the block that are hosing the piston/ bores down like a wet t-shirt contest bimbo?

Forged Pistons are more ridgid and hold their shape better than cast or hyperuetic (spelling big time on that one). misisng squiriters is probably not recomended regardless of the type of piston used. i think the best solution is to find out WHY they get clogged. is it crappy manteneice schedule? wrong oil? are they too small? sh!tty rings that allow too much blow-by and coke up the oil?

[Nemesismachine]

[turbovanman²]

I'd say get rid of them, we don't use them and other cars don't. Sure, it would be nice but having crank walk isn't nice either.

If you really must have them, then retrofit them like the older engines.

I know my friends TIII took out 2 thrust bearings and cranks due to the Double Diagraph? sic, clutch and low oil pressure, so maybe they are onto something.

[turbovanman²]

Unfortunately Cliff's site went down some time ago. I also heard he sold the car and is back to 2.2L because they couldn't keep a head gasket in it. I'm hoping for the best for my 2.5L TIII.....not making a bunch of HP like Cliff was, just want to make my SL fun again! Honestly I will probably just use stock head gasket and maybe ARP studs.

I have never blown a head gasket, everything else but no head gasket.

[rich tideswell]

If you really must have them, then retrofit them like the older engines.

Can you please post a picture of what you're talking about?