2G Need help picking bottom end bearings for 98

[kevster0G]

I have a 98 gst 7 bolt Im doing a light build on, scat rods, nippon racing pistons. Planning for 400 wheel max hp probably gonna run 350 majority of the time. What rod bearings are good? And clutch, gonna put arp rod bolts what about girdle bolts? Ik arp head studs and mls head gasket. Should I do counterbalance shaft delete? Heard that it can cause oil pump failure. I’m sure a lot of you are going to say what I’m doing is over kill for the power more of an assurance thing and if I ever got hp hungry in the future I wouldn’t have to worry

 

[curt-s]

Nippon pistons? Why them of all the choices, especially with scat rods

King XP gets my vote for mains and rods
Girdle uses main studs. Search out what you need to use a girdle.
No, balance shaft delete does not kill pumps if you use the proper grooved/reliefed stubby shaft.
MLS needs a proper surface finish
Some say head studs needs a torque plate bore and hone but I contend only for high power applications where error tolerances are tighter

 

[motomattx]

Factory bearings are probably the most accurate and maybe your best choice, King's are good but the XP is a race bearing that wont allow debris to bed itself into the bearing surface and will instead be more prone to spinning a bearing unless you do pretty good maintenance on the car, if King is the choice I would suggest regular King bearings if you must and forgo the XP series for a build like this, most of the name brand bearings would work, again though I would stray from any "race" bearings for a mild build, and OEM would be my top recommendation for something like this.

 

[kevster0G]

Nippon pistons? Why them of all the choices, especially with scat rods

King XP gets my vote for mains and rods
Girdle uses main studs. Search out what you need to use a girdle.
No, balance shaft delete does not kill pumps if you use the proper grooved/reliefed stubby shaft.
MLS needs a proper surface finish
Some say head studs needs a torque plate bore and hone but I contend only for high power applications where error tolerances are tighter

I ended up getting the nippon racing pistons because they supposed to be rated for 550 whp and they came with a kit with the scat rods so I got a good deal, about $500 for the combo I’ve used the pistons in other builds they have not disappointed! Also never really plan to go above 400 since the transmission is still stock and probably won’t be touched for a long while. Thanks for the feedback much appreciated!!!

 

[Spleen8urLSX]

“Nippon Racing” pistons are literally stock replacement 2g pistons with “Nippon Racing” slapped in the eBay ad. They’ll do just fine for what you want to do but aren’t anything special. As far as bearings go any name brand off the shelf bearing in the correct size installed correctly will do just fine, King, Clevite, ACL, etc, as long as the journals on the crank are good and your clearances are proper one won’t really be better than the other. As far as the MLS head gasket goes also 100% not necessary for your goals, unless the block and head surface are machined to the correct finish the MLS gasket will be more problems than a help, and also think of a head gasket like a fusible link, if a tuning error or something along those lines occur and you see a bad detonation the MLS gasket is more likely to hold it in and result in torching a perfectly fine head, whereas a composite gasket is more likely to blow out giving it somewhere to go and potentially saving the head. Unless you’re looking at making 600-700+ a Felpro composite or OEM composite is what you want.

 

[curt-s]

Factory bearings are probably the most accurate and maybe your best choice, King's are good but the XP is a race bearing that wont allow debris to bed itself into the bearing surface and will instead be more prone to spinning a bearing unless you do pretty good maintenance on the car, if King is the choice I would suggest regular King bearings if you must and forgo the XP series for a build like this, most of the name brand bearings would work, again though I would stray from any "race" bearings for a mild build, and OEM would be my top recommendation for something like this.

Indeed, King XP is to ACL Race, except (I believe) better designed. On my previous engine I went King XP mains and Clevite 77 rods. I agree, full out race bearings is way too often put in engines that don't need them.
I was young and impressionable.

 

[97egl]

Agree 100% with Spleen8urLSX about the headgasket. You are going to be wasting money on machine work and a more expensive gasket that you don't need. You'll blow your stock transmission due to power way before the gasket even thinks about letting go unless you have a terrible tune and then as mentioned the gasket makes a nice "failsafe". If you plan for enough power in the future to kill a composite headgasket you are going to need to replace the pistons too so there isn't really the "future" benefit you are looking for by overbuilding the headgasket. IMO

Counterbalance delete is fine. Use the 1.6 dodge colt stub shaft replacement or cut the shaft and plug the oil galley hole and you'll be good. Its people using aftermarket kits that mess up the oil pumps when they delete.

Clutch wise I would recommend the ACT 2100 or 2600 if you think you will really be going for 400hp. I'd recommend sticking with 350hp or less. Still makes a very sporty fun daily but under 350 you should still get a good lifespan out of the transmission as long as you aren't doing stupid things like dumping the clutch.

Personally on the bearings I always use Clevite "Tri-Metal" or "P" They last longer than factory type aluminum bearings tend to but still are soft enough that they will embed foreign material. Whatever you go with just stay away from "Race" bearings.

I would do ARP headstuds but I wouldn't see a need for ARP girdle bolts at your power level. Again if you want to build for more power in the future you will have to tear down the engine to replace the Nippon pistons so no reason to add them now.

I do think the Nippon Pistons are good for your current build even though others questioned using them. Forged piston require more clearance because they expand more so on cold starts you end up with more wear happening. Cast pistons you can have a nice tight clearance so less wear. And if you never decide to build the car more it should be good for years to come without issues.

 

[dwb]

I did a mostly stock rebuild last summer with a very similar list of parts except an OEM headgasket, no girdle, and 6 bolt rods. I had already deleted the balance shaft prior to rebuild. You WILL notice more vibrations without the BS, especially if you have broken or solid motor mounts. Just be sure to do the BS delete properly with the OEM stub shaft (like others have said) and rotate the bearing to block the exposed oil galley.

I used Nippon pistons in mine as a stock replacement. They work good for what they are. I don't think it's overkill for 400hp, that's about the upper range for those pistons. I also used ACL Aluglide bearings, both rods and mains. They are very soft and I chose them for the longevity of my crank. I'd rather replace a set of bearings than the crank if something were to go (mildly) wrong.

A fair warning, people on here will flame you for your piston choice and possibly anything else you reveal that doesn't align with their agenda. It happened to me. End of the day it's your build and your choice what you put in it. Do your research and I think you will be happy with the results.

 

[Spleen8urLSX]

I did a mostly stock rebuild last summer with a very similar list of parts except an OEM headgasket, no girdle, and 6 bolt rods. I had already deleted the balance shaft prior to rebuild. You WILL notice more vibrations without the BS, especially if you have broken or solid motor mounts. Just be sure to do the BS delete properly with the OEM stub shaft (like others have said) and rotate the bearing to block the exposed oil galley.

I used Nippon pistons in mine as a stock replacement. They work good for what they are. I don't think it's overkill for 400hp, that's about the upper range for those pistons. I also used ACL Aluglide bearings, both rods and mains. They are very soft and I chose them for the longevity of my crank. I'd rather replace a set of bearings than the crank if something were to go (mildly) wrong.

A fair warning, people on here will flame you for your piston choice and possibly anything else you reveal that doesn't align with their agenda. It happened to me. End of the day it's your build and your choice what you put in it. Do your research and I think you will be happy with the results.

I specifically remember a handful giving you the business when you chose to go 2g pistons on 1g rods, despite 30 years of documented history showing that to be a great bang for the buck combo. Shoot, I’ve got the printed plaque of the 1998 turbo magazine feature on Shep’s red 1gb running 11s in street trim, clearly states he was using that combo back then for that set up, yet no matter what has been proven time and time again some “expert” with zero credibility behind their statement will always tell you otherwise. But you said it best, just do the research, years of what works and doesn’t work is out there.

 

[curt-s]

personally I was just curious about the upgraded rods but basically oe pistons. It seemed like an unusual combination. The piston will limit the power that can be pushed to the rod, so if more power was desired later, you'd be changing the piston anyway. You're not future proofing anything there. It's just one less thing to buy down the road but one more thing being underutilized until then

Now if a package comes up cheap, well, that's a no brainer

If "by a long time" you'd be doing the trans, that will be a limiting factor. One, parts availability by then.
Two, depending on how long and how it's been driven, you might be reconditioning it all at that point anyway.

 

[FIBA M - EC17PSE]

unless you plan on beating it stick with a softer bearing to absorb the loads better, race bearings are great for high revs and loads of loading going on but will be less forgiving for a daily for the most part, while they dont require checking they need to stay as clean as possible so a good coated crank journal is key, any polished or cut cranks require a softer bearing to cope better. for the 400 hp a good set of oem bearings will be fine, oem is good and something a bit more of a coating would be a slight increase over stock.

 

[1990TSIAWDTALON]

I run ACL tri-metals in all of my 4g motors. They are a hard bearing, but I'm not a fan of soft mains and rods. On a domestic motor I run Clevite 77's.
Just what I've always used.

 

[donniekak]

Some say head studs needs a torque plate bore and hone but I contend only for high power applications where error tolerances are tighter

Strangely enough we found the opposite to be true with stock block castings. At low to medium power output the bore distortion from the studs and the clamping of the head are the largest contributor to bore distortion. Somewhere between 200-300hp per cylinder the block starts to distort more from the cylinder pressures and rpms than the studs.

 

[curt-s]

That makes a decent amount of sense actually. It would be great if we could actually see this distortion, like a 3D laser scan of the bore when studs are used.