2g dsm crank same as ours?
If it's the 7 bolt it will fit just fine. (so will some of the 6 bolt fit but it wont hold very high torque on 6 bolts alone)
The non-evo 4G63 the block and crank makes use of slightly wider main and big end bearings (~2,5mm ) and slightly wider clips that seat them in place, however the crank is the same size and has the same lateral thrust support machined into the crank to prevent crank-walk. Main bearings are the same diameter and thickness and all are interchangeable with exception of the central one. On the older model 4g63 the bearings supported the crank to prevent walking, where as on the evos the crank is supported by two 1/2 circle bearings against the centre journal of the crank which locks the crank in place in the block. On the later models the support comes from the block with two 1/2 circle shim bearings.
What i normally do is use the ACL race bearings from the older 4g63 cranks which are ~2,5mm wider and then file the little tongues on them to seat properly. The extra support plays a role in managing 900hp. It does take some engineering though as you don’t want the bearings to float from not being seated tight, but they fit fine and don’t touch on the crank if done properly.
My comets are based on what I build and tune all the time, not speculation or Google write-ups
.
The non-evo 4G63 the block and crank makes use of slightly wider main and big end bearings (~2,5mm ) and slightly wider clips that seat them in place, however the crank is the same size and has the same lateral thrust support machined into the crank to prevent crank-walk. Main bearings are the same diameter and thickness and all are interchangeable with exception of the central one. On the older model 4g63 the bearings supported the crank to prevent walking, where as on the evos the crank is supported by two 1/2 circle bearings against the centre journal of the crank which locks the crank in place in the block. On the later models the support comes from the block with two 1/2 circle shim bearings.
What i normally do is use the ACL race bearings from the older 4g63 cranks which are ~2,5mm wider and then file the little tongues on them to seat properly. The extra support plays a role in managing 900hp. It does take some engineering though as you don’t want the bearings to float from not being seated tight, but they fit fine and don’t touch on the crank if done properly.
My comets are based on what I build and tune all the time, not speculation or Google write-ups
.
As for the other bearings, it's important that the tangs fit, but having a narrower bearing is in some instances desirable. I can't speak for 900 hp, but I would think the majority of high hp EVOs are using an EVO crank with the stock width bearings. My concern being that the wider bearing will suck up some power.
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From: JHB
Clearance for the crank (Lateral is 0.05MM - 0.25MM) most ive done are 0.14mm (not sure what that is in inches) however as stated earlier on the oder crank the thrust washer is part of the bearing in the centre and the crank has a wider space to accomodate this. The evo crank makes use of a normall sise journal space (note that the journal is the same just the lateral space differs) and use thrust washers seated in the block on either side.
re wide bearings - I agree 100% with your comments on the wider bearings, and would not do this on a 500hp car as its pointles. In fact there is no point to use copper base bearings on 500hp - rather the OEM alluminium white metal.
On high torque cars it has its merits and as i chase reliability when i build cars and not absolute numbers, its important that it can last the distance. Trade off is some lost KW due to friction. But not much. what you will notice is that the wider bearigs are no wider than the seat of the journals or the contact area on the crank, hence your not going over on tolerances, just making use of all that was provided from by the factory.
Im sharing what i do with those who read - its not to say its the best, but it serves me well.
Adelin
re wide bearings - I agree 100% with your comments on the wider bearings, and would not do this on a 500hp car as its pointles. In fact there is no point to use copper base bearings on 500hp - rather the OEM alluminium white metal.
On high torque cars it has its merits and as i chase reliability when i build cars and not absolute numbers, its important that it can last the distance. Trade off is some lost KW due to friction. But not much. what you will notice is that the wider bearigs are no wider than the seat of the journals or the contact area on the crank, hence your not going over on tolerances, just making use of all that was provided from by the factory.
Im sharing what i do with those who read - its not to say its the best, but it serves me well.
Adelin
Reading this I thought it would be the thrust that was different. From what I understand the crankwalk issue on the 7-Bolts was due to improper thrust. How much thrust should you expect when using the 7-Bolt crank in an EVO block?
As for the other bearings, it's important that the tangs fit, but having a narrower bearing is in some instances desirable. I can't speak for 900 hp, but I would think the majority of high hp EVOs are using an EVO crank with the stock width bearings. My concern being that the wider bearing will suck up some power.
As for the other bearings, it's important that the tangs fit, but having a narrower bearing is in some instances desirable. I can't speak for 900 hp, but I would think the majority of high hp EVOs are using an EVO crank with the stock width bearings. My concern being that the wider bearing will suck up some power.
Last edited by popadel; Sep 12, 2008 at 04:42 AM.
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