B18C ARP main stud issues

Hi Andre and everyone

I have a honda B18C block I'm building up for 9000 rpm NA use.

The issue is torque on the ARP main studs. When receiving the engine from the machinists, they have changed the torque on the main studs from ARP setting 80ftlb to 50ftlb. They say the reason is 80ftlb distorts the block too much. I would have thought this shouldn't matter as the line hone should have removed any distortion?

The honda factory torque is 49ftlb for the center 3 mains with the girdle and 56ftlb for the number 1 and 5 main caps. So the new torque is less than factory.

I'm now in a predicament as to what to torque these to. I'm worried I'll distort the holes if the machine shop line honed at 50ftlb and I go higher but if I only torque to 50ftlb they may come loose and the extra clamping benefits of the fastener will be wasted? Will it need extra clamping than factory? Power goals are around 170kw and roughly 9000rpm.

I've only plastigauged at this stage as I can't get to measurement tools for another couple of weeks however after much mucking around have used factory honda bearings to get 0.0014" clearances on all of the mains except the front. The front is 0.0015" mostly but tapers toward the very front of that journal to around 0.0020".

Using all same bearings before adjusting to achieve equal clearances the taper through all of the main journals front to rear seems to be 0.001". Is that acceptable accuracy for a block that's just been freshly line honed?

I'm a little hesitant to hit the machine shop up because I'm not an experienced car engine builder and not sure what's acceptable. Also worried they aren't going to take me seriously with just the plastiguage measurements at this stage. All measurements have been done with the crank and bearings dry as per your plastiguaging video. Crankshaft has be orientated in the same position for every measurement. I've not plastiguaged with the higher torque yet but even if I had It won't show me if the mains are still round?

Will higher torque on the mains distort the roundness of the piston cyclinder bores given the aluminum open deck design?

Sorry for the novel, just not sure where to go from here.

Edit: I have now tried 80ftlb on the studs and it distorted the main bearing tolerances from the 0.0014" that I had to less than 0.001". The plastiguage was squashed beyond its measurable range.

Do I re align hone it at 80ftlb or stay at 50ftlb?

Cheers Andy.

Bottom line is the machine shop ****ed up, and are trying to cover their ***s.

Studs and bolts are designed to have a specific stretch, achieved by the torque applied - if you use the ARP with the OEM torque (let alone less) then they are technically 'loose', and aren't doing the job they are designed for - they may even allow the nuts to loosen and it'll certainly promote cap/girdle walk, which is one of the main reasons for the studs in the first place.

You can either use the factory studs (new) and OEM torque (better double check for distortion, even then), or have a GOOD, RELIABLE, COMPETENT machine shop align bore the engine using the ARP studs and torque settings.

I would be loathe to have the incompetent 'shop re-do the work because, IMO, they were completely at fault and are giving you terrible advice that will compromise your build, rather than doing the right thing which would be to do it correctly in the first place or, at a minimum, apologise to you and do it correctly, at their expense.

There are some excellent machine shops in NZ, but there are also a lot of muppet-heads who can barely manage to do a basic recondition. That said, even the best shops will make mistakes - but "it's the putting right that matters", as the ad' used to say.

Where are you? I haven't had them do much, but been very happy so far with http://www.waer.co.nz/ in West Auckland. As with any non-standard work, make sure they know what you want done, especially if non-stock.

Oh, if there's a car club or race track near you, see if you can have a talk to some of the people there about who they use for their engine machining - they're usually well aware of the places to avoid, and the places that can be relied on.

It sounds like potentially your machine shop is sub-par. In fairness what they've done in terms of under-torquing the ARP studs is not uncommon but also not really a recommended technique. If you're going to under-torque the fastener then you're not achieving the recommended clamp so you may as well stick to the stock bolts. For some reason this technique has been pretty common in the Subaru EJ20/25 building world.

What I can say is that I've yet to build an alloy block engine that hasn't distorted the main bores when aftermarket studs are used. Inevitably they will require line honing to correct the main bearing tunnel. It's kind of a non negotiable. Your post suggests the machine shop has line honed the block though so I'm a little confused why they've still under-torqued the studs?

As for the taper you're referring to I'm a little confused - Initially it sounded like this was on just the front journal but later you mention it's on all? 1 thou taper is not something I'd accept. Granted the engine will probably run ok but it's hardly a good starting point. It would however be quite difficult for the machine shop to achieve a consistent 1 thou taper on every journal during line honing too which is weird.

In short I'd raise your concerns with the machine shop. If they don't want to take your job seriously then move on and go elsewhere.

Hi Andre, cheers for the reply!

Does my build need studs in your opinion or should I have stuck with factory fasteners at my RPM and power level?

I didn't write that first post very clearly so i'll try and clarify.

- The block has been line honed, but only with the studs done to 50ftlb.

( I am certainly confused as to why they didn't go to 80, maybe its easier and less risky for them to stuff up the machining if the main bearing bores aren't majorly out to begin with? I was never consulted, just got handed back the finished article saying to only go to 50ftlb)

- The taper of approx. 3-5 tenths is only on the front #1 journal.

- The sizes of main bearing colors from the 1st journal to the 5th journal step down along the length of the crankshaft, IE the thick bearings (honda brown) top and bottom on the 1st journal and thin bearings (Honda yellow) top and bottom on the 5th journal. the 2nd 3rd and 4th journals using combinations of brown green and yellow to achieve correct clearance in between.

(What I was getting at here was, shouldn't the main bearing bores use all the same colour bearings front to rear if the line hone has been conducted in a straight line front to rear? The difference in main bearing bore size across the length of the entire block is .001" with approx half of that being on the #1 journal.)

I'll try my machine shop again (GER), and see what they say and if they will redo the line hone at 80ftlb although I'm not sure I trust them much anymore.. While i have been waiting i have managed to get in contact with a couple of other honda engine builders who have also said they under torque arp mains in Honda blocks. Speedfactor in Tauranga do factory Honda torques on arp studs when not line honing and Harris performance(formally lynn rogers) mention the k20 blocks they build are only done to 60ftlb instead of the ARP 85ftlb setting. I have also found posts from people in the states that say they use the studs at hondas factory torque, so the practice definitely seems prevalent in the honda engine building community as well.

I have also just received a reply to my email to ARP stating to use factory bolts if not going to torque the ARP to their recommended settings. Some very different opinions out their making my first performance engine build not as straightforward as I had hoped. There's a lot of $ in parts on the line if it goes pear shaped!

Have you got any recommendations for reliable machinists in NZ? Ideally Auckland but will go elsewhere in the country to get it done correctly. Its just a bit gutting as I spent almost 3k on just the machining and balancing operations and will have to pay that off and save up again before looking elsewhere. I thought I had done good research before picking my machinist but have come up short by the looks of it.

Cheers

Andy

I am aware that the practice of using ARP fasteners and not torquing them to ARP's spec is prevalent. For me it's basically the same as buying the ARP fasteners and putting them on the shelf so you feel good, then going ahead and using the stock bolts. Will it work? Yes, quite likely. Is it worth doing? In my personal opinion no. If you're not going to use the recommended torque then stick to the factory bolts. In your specific case I believe you'd quite happily get away with the stock bolts but I usually fit ARP studs as a matter of course with performance builds for peace of mind.

The taper in the main tunnel that you have front to rear is not right but actually not unheard of. Keep in mind I'm not a machinist but I've dealt with machinists for years and had my share of blocks line honed and often with less than ideal results. It's actually a trickier operation than it seems on face value. That being said, yes you should expect the bores to be a consistent size.

I'd recommend you talk to Tony or Anthony at Marsh Motorsport. We recently had them machine our EVO 9 parts and I was happy with the results we received.

Cheers, greatly appreciate the reply.

I'll get It re line honed at 80 ftlb .