Arp Rod Bolt Help

[Griffin]

after some advice, fitting a known good r34 motor to a gtr, is it advisable to change to arp rod bolts without changing bearings? are the factory bolts a weakness? Id rather not disturb the short motor but if it will be ok to keep the bearings and retourque without taking the caps off im happy to. Also running 264 cams , whats the thinnest head gasket I can use to bump compression up?

[blue_vl_t]

Really, I wouldn't bother, how much power are you looking at making, if it's under 450rwkw I'd leave the stock ones in place.

[Griffin]

ok we were looking around 400kw. id rather not mess with a good thing if not necessary

[doo doo]

I'd change to arp rod bolts with 400rwkw. (known a gtr to lose a bottom end on the dyno due standard rod bolts at that power level) But there's more than just putting the bolts in however, you need to torque them up then hone the main journal rod end for round and correct size so it's pull engine apart time. I'm not sure how you'd get the rod bolts in without disassembly though (if that's what you mean?)....That said, I have a spare set of standard rods with arp rod bolts that have been resized/honed and are ready to go, pm me if interested

[Griffin]

I have the rod bolts, not sure whether r&r on the bolts will disturb the bearings. they will be re torqued.has anyone done it? the caps wont even need to come apart.

[doo doo]

Ah, what rods are in the engine?

If you have standard rods the bolts need to be press fit into the main rod body, requiring removal from engine. I'm guessing you have arp rod bolts that are for aftermarket rods that screw in from the cap side? (These won't work with stock rods- arp also do rod bolts for stock rods that are different). See attached pic- left is aftermarket and right is standard, you can see the difference in how the bolts fit.

Edited March 15, 2014 by doo doo

[Griffin]

the engine is an N1. im not sure if the rods are good for 400kw +. The old ones are aftermarket hence the bolts going through the cap. Thanks for clarification. i was unaware of the difference. What's my next step?

[Griffin]

the engine is an N1. im not sure if the rods are good for 400kw +. The old ones are aftermarket hence the bolts going through the cap. Thanks for clarification. i was unaware of the difference. What's my next step?

[Griffin]

the engine is an N1. im not sure if the rods are good for 400kw +. The old ones are aftermarket hence the bolts going through the cap. Thanks for clarification. i was unaware of the difference. What's my next step?

[Griffin]

the engine is an N1. im not sure if the rods are good for 400kw +. The old ones are aftermarket hence the bolts going through the cap. Thanks for clarification. i was unaware of the difference. What's my next step?

[KiwiRS4T]

What do you know about the history of the block? If you don't know for sure just bite the bullet and pull it apart, measure and replace as necessary (rings and bearings or whatever is necessary for your more than 400Kw goals).

[Griffin]

its a low mile N1, im not sure if the rods/bolts are different on n1. Ill be fitting new head gasket, arp studs and restrictor before we put it in.

[blue_vl_t]

My first reply was probably a little short. There have been a few cars these days running stock rods and bolts over 400rwkw. The main reason I turned away from changing them is because as mentioned above, by the time you fit them, resize the rods, fit new bearings. You will have the pistons out and the head off, it can easily escalate to a full engine rebuild. So it's a bit of a weigh up between, do you risk running the bolts over 400rwkw or invest more money than you were planning on the engine.

[SiR_RB]

Just keep the revs to a sane limit, I wouldn't go over 7800-8000rpm

And as others have said, new rod bolts and they will need to be closed and honed plus new bearings to suit

[Griffin]

ok cheers, do you guys think I should still take the head off to fit studs, mls gasket and oil restrictor? If so what size gasket will I need for 86mm bore with highest comp ratio possible?

[GTRPSI]

You will need to take off the head to get the pistons out to resize the rods for the new rod bolts.

[Griffin]

ive decided not to mess with the rod bolts so will only need to take off head to fit parts mentioned in previous post.

[SiR_RB]

I think head gasket and arp bolts would be a worthwhile exercise now that the motor is out

.8 or .9mm thickness gasket should help raise the compression abit

[ido09s]

At 400rwkw you have more to worry about than the rod bolts

I would be putting a Tomei oil pump and large volume baffled sump on it before i bothered with the bolts. If your that worried about it all letting go rebuild the whole thing and be done with it because you will never be happy with it until you do