Free horsepower?

[Ondonti]

Well here its only 3.0L mitsubishi bottom ends.

I dont know how your scraper takes into account differences between the cast and fordged cranks available for the 6g72.


I just wasnt sure how you could make up the thickness issue properly and have the pan seal around the crank "humps"

[Kevin Johnson]

Quote:

Originally Posted by Ondonti Well here its only 3.0L mitsubishi bottom ends.

Aside: There is a great deal to be discovered by analyzing across different marques and engine designs. For example, the bottom end in the Nissan KA24e and de runs a girdle as does the SR20. Unpublished Nismo research indicates that the girdle costs the SR20 5% in power output through windage losses. Many racers have known that by cutting out the arms of the KA girdle or reverting to individual caps from the truck block a performance increase can be realized. This is presuming that your ap does not require the additional bracing -- remember that many times parts in modern engines are modified to simply reduce NVH. That was one of the reasons the bedplate design (a type of girdle) was used in the Neon 2.0 and I think also why they included a crank scraper in it originally.

Back to the 6G72.

Quote:

Originally Posted by Ondonti I dont know how your scraper takes into account differences between the cast and fordged cranks available for the 6g72. I just wasnt sure how you could make up the thickness issue properly and have the pan seal around the crank "humps"

It could be that the forged crank is significantly different in contours from the cast. If it was a Mopar crank I would think definitely so but with a Mitsubishi design I could not say. I know from owners of Buick GNs that the forged and cast 231 cranks are the same general design. Lots of variance across the industry and time.

Actually, if I had the opportunity I would just change the 4-bolt 6G72 design to one that attaches to the girdle, maybe also with the earlier engines. That is what I did with the 2nd gen 4G63 and 64 engines. But I have a lot of other designs to complete before I can do that.

[Ondonti]

attaching to the girdle sounds pretty cool.

I really dont know the physical differences between the cast and forged cranks. I assume some clearances for counterweights are going to be different

All factory chrysler 6g72's have cast crank and the 2 bolt main. Then mitsubishi depends on the year and whether its a 12v or 24v sohc/dohc.


6g72's have main bearing problems so I dont think cutting up the girdle is a good idea.

[Boogieman142]

main bearing problems, thought they just had thrust bearing problems(yes i know its part of a main)

[Ondonti]

Quote:

Originally Posted by Boogieman142 main bearing problems, thought they just had thrust bearing problems(yes i know its part of a main)

Thrust washers are a problem with 1st gen 4g63's that use a VERY strong pressure plate. not for later 4g63's or 6g72's. The fix is to take the car out of gear and not hold the clutch in (thats what kills the thrust washers). Personally I would do that on any car with a strong pressure plate.

6g72 main bearings only have problems when you are making over 800whp. Then tend to get flattened if you get ANY detonation. Also there seems to be some crank flex that hurts the some of the main bearings. That hasnt been confirmed though.
I just assume if you cut up the girdle you might start killing mains at a lower HP.

[Kevin Johnson]

Quote:

Originally Posted by Ondonti Thrust washers are a problem with 1st gen 4g63's that use a VERY strong pressure plate. not for later 4g63's or 6g72's. The fix is to take the car out of gear and not hold the clutch in (thats what kills the thrust washers). Personally I would do that on any car with a strong pressure plate. 6g72 main bearings only have problems when you are making over 800whp. Then tend to get flattened if you get ANY detonation. Also there seems to be some crank flex that hurts the some of the main bearings. That hasnt been confirmed though. I just assume if you cut up the girdle you might start killing mains at a lower HP.

I think the thrust washer problem is with the 2nd gen 4G63 engines (the ones that first starting using the complete ladder girdle coincidentally -- not causally). One shop proposed a theory that the failures are because of the design of the oil squirters and main bearing oil circuit and I think it is correct. The jets have valves in them that are intended to close at low rpms ergo lower oil pressure/volume. Debris can get in them over time and hold them open as well as simple statistical fatigue and deviation from spec of the tiny valve springs.

At low rpms is when people will be holding in high (or stock) pressure clutches and if the secondary splash oil flow to the thrust washers is lowered because of bleeding off of pressure/volume from the stuck squirters in the same circuit, accelerated wear will occur.

I recently saw an explanation that the factory in Normal, IL improperly machined the thrust surfaces. I think that problems like that would show up statistically early in engine life and the crankwalk problem is typically with higher mileage and rebuilt engines. I definitely think that if a previously damaged thrust washer bearing surface was seated against a new thrust washer then accelerated wear would occur. This secondary causal chain might be what gave rise to speculation of it being the primary issue.

Seems like a strong possibility that this problem (subsequently corrected I think) crosses over to the 6G72 engines of the same vintage using oil squirters.

Definitely the girdle is an advantage with very high output forced induction engines. I am just wondering if lower output versions could use or try the mod of removing the arms.

Detonation is always a killer, of course. It might be that at high rpms and boost the engine oil is extremely aerated -- but typically damage from that first shows up in the rod bearings. A possibility is that more main bearing clearance is required with a crank that is distorting for whatever reason. I talked with a guy running a 557 Ford in road racing and he told me that the original clearance they set up for the mains was simply not enough -- I think he said they ended up running about .003" or .0035".

[Ondonti]

Well a lot of the faster 6g72's are using non turbo blocks that dont have the oil squirters.....they even go with 2 bolt mains and the stock girdle.

No one has ever posted a definitive bit of information about how possible poor oil management in the block causes problems. just speculation which gets argued back and forth.


Yeah and you are right about the 2nd gen!

[Kevin Johnson]

Quote:

Originally Posted by Ondonti Well a lot of the faster 6g72's are using non turbo blocks that dont have the oil squirters.....they even go with 2 bolt mains and the stock girdle. No one has ever posted a definitive bit of information about how possible poor oil management in the block causes problems. just speculation which gets argued back and forth. Yeah and you are right about the 2nd gen!

An interesting line of thought would be -- why was the girdle design changed? And exactly what else was changed in the block? I know the shop that analyzed the 4G63 2nd gen actually went to the trouble of slicing up blocks to see how the oil passages were configured.

[DustyR/T]

Quote:

Originally Posted by DustyR/T had one. It only made my oil pan leak like a sith to this day. As well, It wasn't cut well. It was supposed to be CNC machined, but when I turned it by hand it hit the scraper. I tried shaving it where it hit, but it was in multiple spots. I just said forget it and took it out for good.

Well I know this post has been long killed, but I was refreshing some posts and would like to rephrase the above statements.

Kevin does make a good product and even though in a perfect world, all engines would be equal and you wouldn't have to shave any off, the reality is that that isn't the reality. I had bad luck because I assumed mine was a "good" cut and just installed it. I cranked the motor and the noise was astounding. I shut it off immediately and dropped the pan again. I am retentive about using drained oil again so I recycled it and bought new oil and found out where it was grinding. I filed it down and installed it. Stated it up again and it did it again. I was frustrated and dropped the pan again. Kevin couldn't help me like he tried to because by the time he found out about my problems when I called him, I was leaving for college after the weekend. (BTW he was even nice enough to drop them off at my house when I was away at college and it was a nice surprise to come home to.) I stubbornly removed them for good and sat them in my garage. Later while I was away I found out my dad disposed of the "unknown metal matter" through his garage cleanout. I was upset because I couldn't use the product. I was upset because I had an oil leak post-install of the scraper and removal to the point that I attempted the oil pan re-gasketing 9-10 times (NO KIDDING) over the course of 3 months. I realized all too late that it wasn't his scraper that caused my oil leak. It was the gaskets I attempted using after the scraper removal + a crank seal leak that occurred about 2 months later. (For those who are interested, don't buy the CHEAP FELPRO CORK gaskets.) My new block has the premium Permadry stuff and it has the thicker lip at the bottom and tapers towards the top of the lip to compensate for the shape of the pan to block mating surfaces. Back to the story, I was upset and angry w/ Kevin because I blamed his product for my leaks and aggravation. (Who wouldn't be aggravated after doing an oil pan that many times?!) But I should have evaluated the geometry of my block and procedure before I talked crap about his product and business. He is honestly one of the most helpful honest business vendors around. Anyone who has done business w/ him knows this. I just want to take this chance and thank Kevin for his patience, support for us TD'ers and know that good things such as scrapers are beneficial but don't jump into installation w/o planning ahead and to TURN THE CRANK before initial start-up to prevent damage to scraper and crank. Thanks Kevin for being a good vendor and a good support member.

Rich