Hi all,
Posting this up for informational purposes, as I haven't found a good single source of information related to this topic.
I spent a significant amount of time the last 2 days researching the approaches others have attempted, in order to move from the M10x1.25 head stud size to the larger M11X1.5 found on higher performance Honda 4 cylinders (B Series, K Series, etc). I am wanting to modify my engine to accept these, and figured I would share the process of what I come across along the way to try and help others interested in doing this.
From what I've gathered, a few things need to happen in order to complete successful modification to accept the larger head studs:
1. Sourcing Head Studs
This process took a bit of comparison via Google, along with contacting ARP to verify the kit bolt length average sizes.
SoulEngineering was kind enough to inform me that DOHC ZC engines run M11X1.5 cylinder head fasteners. After a little bit of Google time, I was able to confirm this. I also found that ARP doesn't officially offer ZC bolt kits, but there are many aftermarket companies that create kits for these engines using hardware from other ARP kits OR directly sourcing individual pieces of hardware direct from ARP to offer complete plug and play head stud kits for the ZC.
**Because of the nature of these DOHC ZC kits being pieced together, I did not spend the time contacting companies that offered these pieced together kits for the ZC, to ask about stud lengths used in those kits, so I have no idea if they are comparable or where they fall in the below table I put together. If you have size or length measurements for the DOHC ZC bolt kit lengths, I would love to know about them to add them to the table!
From what I've researched, I found the following:
For the D15B, D16Y8 and D16Z6 engines at least, the best M11X1.5 stud length bolt kit that has been CONFIRMED to work on more than one build variant is ARP's SRT4 bolt kit offering.
Both D-Serious's D15B (YouTube channel D-Serious) and DSO's own Jvtec8K's D16Z6 have utilized the SRT4 head stud kit in their builds.
**Another FYI when purchasing the SRT4 stud kit: Apparently around 2007, there were reports of ARP mis-packaging these kits with washers and nuts that were too small for the application. The result in high performance applications was that the head aluminum would sink/depress around the nut/washer, causing loss of clamp load. The recent kits should have appropriately sized fasteners, just putting this out there in case someone is offering abnormally cheap SRT4 stud kits, be aware!
2. Modifying Block Threads
There are typically 3 ways to do this:
#1 lacks the ability to provide full, proper thread engagement with the stud, because removing ALL of the M10x1.25 threads from the bolt holes will leave very little aluminum exposed to properly allow an M11x1.5 tap to cut with. The threads will be shorter than ideal, and chances are they won't properly engage the stud threads.
#2 is a better alternative than #1. The HeliCoil inserts are not the "Cadillac" of inserts by any means, but you can typically stack them together inside the blind hole to provide full thread engagement for whatever fastener you are trying to use. The HeliCoil inserts fully engage the aluminum, and offer a steel interface for the studs to latch on to. Since the HeliCoil insert is going larger and wider into the aluminum than stock, there is more surface area engaged against the block aluminum, so I would definitely trust these style of inserts with the larger studs, even in a performance application, if nothing else was available:
#3 is the most recommended process by far, and is Honda's OEM method to repairing block thread strippage. Every Honda dealer should have these kits in their service departments, so if you work at a Honda dealer, f*** you ya lucky bastard lol. If you DON'T work at a Honda dealer, then acquiring the TimeSert kit might be a challenge. It was for me, as every machine shop in my area did NOT have this kit, and Honda dealerships I contacted would not let me use this tooling even if I provided my own insert refills. I ended up breaking down and purchasing this kit myself, just so I could perform this modification. I will also offer this tool for rental here on DSO for fellow members wanting to go with larger head studs, as a sad attempt to recoup my own costs of buying this kit lmao. I will post up a link to the thread I will add to offer the rental and conditions. This is what the kit looks like:
3. Modifying Cylinder Head Bolt/Stud Passthrough Holes
The cylinder head passthrough holes will need to be enlarged to properly clear the wider diameter of the head studs, these guys:
Choose the smallest possible drill bit that goes slightly larger than the stud, and I would spring the cash to buy this drill bit brand new so it cuts cleanly, and not use the worn out bits from the general set of bits in your toolbox
Jvtec8k used a 29/64" bit.
Tape off the machined surface around the holes on the block facing side of the head to prevent damage to head surface.
Drill from the valve cover side of the head, down to the block side, to keep potential damage to the head surface as minimal as possible.
Drill STRAIGHT and SLOWLY, trying to keep from cutting off center and removing too much material.
Make sure to lightly touch a deburring tool to the ends of the holes in the block side of the cylinder head after drilling, to remove any burrs and/or to lower any raised spots of aluminum that might have been pushed outward due to drilling.
4. Modifying Head Gasket Bolt/Stud Passthrough Holes
This process is the same as above for the cylinder head, but now you need to use the same drill bit, and drill out the stud/bolt holes in the head gasket to accept the larger stud diameter.
Put painters tape across the gasket surfaces top and bottom to prevent knicking any of the Viton sealant if using an MLS gasket. This is just good practice, regardless of the gasket material.
It is CRITICAL to verify that there are NO burrs or shavings that fall between the MLS inner layers! Take your time here and verify that there are no burrs around these drilled holes. Compressed air and a flashlight is your friend.
Remove burrs around the drilled holes lightly using a deburring tool if needed.
Reassemble and torque studs according to the ARP kit instructions you decided to go with to accomplish this.
Thanks,
Talon.
Posting this up for informational purposes, as I haven't found a good single source of information related to this topic.
I spent a significant amount of time the last 2 days researching the approaches others have attempted, in order to move from the M10x1.25 head stud size to the larger M11X1.5 found on higher performance Honda 4 cylinders (B Series, K Series, etc). I am wanting to modify my engine to accept these, and figured I would share the process of what I come across along the way to try and help others interested in doing this.
From what I've gathered, a few things need to happen in order to complete successful modification to accept the larger head studs:
- Properly sized M11x1.5 head studs need to be sourced, that are similar in length to the typical D Series M10x1.25 ARP kits that are offered.
- Block threads for the head bolts/studs need to be modified to accept M11x1.5
- Cylinder head bolt/stud pass-through holes need to be widened
- Head gasket bolt/stud passthrough holes need to be widened
1. Sourcing Head Studs
This process took a bit of comparison via Google, along with contacting ARP to verify the kit bolt length average sizes.
SoulEngineering was kind enough to inform me that DOHC ZC engines run M11X1.5 cylinder head fasteners. After a little bit of Google time, I was able to confirm this. I also found that ARP doesn't officially offer ZC bolt kits, but there are many aftermarket companies that create kits for these engines using hardware from other ARP kits OR directly sourcing individual pieces of hardware direct from ARP to offer complete plug and play head stud kits for the ZC.
**Because of the nature of these DOHC ZC kits being pieced together, I did not spend the time contacting companies that offered these pieced together kits for the ZC, to ask about stud lengths used in those kits, so I have no idea if they are comparable or where they fall in the below table I put together. If you have size or length measurements for the DOHC ZC bolt kit lengths, I would love to know about them to add them to the table!
From what I've researched, I found the following:
EngineMake | ARPKit# | StudAverageLength | StudDiameter | ThreadPitch |
B18 GSR | 208-4303 | 7.250”/184.15mm | 7/16"/11mm | M11x1.5 |
B16A | 208-4601 | 7.100"/180.34mm | 7/16"/11mm | M11x1.5 |
D16Y8 | 208-4305 | 5.700"/144.78mm | 3/8"/10mm | M10x1.25 |
D16Z6 | 208-4301 | 6.450"/163.83mm | 3/8"/10mm | M10x1.25 |
SRT4 | 141-4204 | 6.300"/160.02mm | 7/16"/11mm | M11x1.5 |
For the D15B, D16Y8 and D16Z6 engines at least, the best M11X1.5 stud length bolt kit that has been CONFIRMED to work on more than one build variant is ARP's SRT4 bolt kit offering.
Both D-Serious's D15B (YouTube channel D-Serious) and DSO's own Jvtec8K's D16Z6 have utilized the SRT4 head stud kit in their builds.
**Another FYI when purchasing the SRT4 stud kit: Apparently around 2007, there were reports of ARP mis-packaging these kits with washers and nuts that were too small for the application. The result in high performance applications was that the head aluminum would sink/depress around the nut/washer, causing loss of clamp load. The recent kits should have appropriately sized fasteners, just putting this out there in case someone is offering abnormally cheap SRT4 stud kits, be aware!
2. Modifying Block Threads
There are typically 3 ways to do this:
- Drill the existing threads out of the block, and retap the aluminum with an M11x1.5 tap
- Purchase a Helicoil kit (and appropriate drill bits) that uses M11x1.5 inserts
- Use the official Honda TimeSert repair kit (P/N 7111) to install solid bodied flanged M11x1.5 inserts
#1 lacks the ability to provide full, proper thread engagement with the stud, because removing ALL of the M10x1.25 threads from the bolt holes will leave very little aluminum exposed to properly allow an M11x1.5 tap to cut with. The threads will be shorter than ideal, and chances are they won't properly engage the stud threads.
#2 is a better alternative than #1. The HeliCoil inserts are not the "Cadillac" of inserts by any means, but you can typically stack them together inside the blind hole to provide full thread engagement for whatever fastener you are trying to use. The HeliCoil inserts fully engage the aluminum, and offer a steel interface for the studs to latch on to. Since the HeliCoil insert is going larger and wider into the aluminum than stock, there is more surface area engaged against the block aluminum, so I would definitely trust these style of inserts with the larger studs, even in a performance application, if nothing else was available:
#3 is the most recommended process by far, and is Honda's OEM method to repairing block thread strippage. Every Honda dealer should have these kits in their service departments, so if you work at a Honda dealer, f*** you ya lucky bastard lol. If you DON'T work at a Honda dealer, then acquiring the TimeSert kit might be a challenge. It was for me, as every machine shop in my area did NOT have this kit, and Honda dealerships I contacted would not let me use this tooling even if I provided my own insert refills. I ended up breaking down and purchasing this kit myself, just so I could perform this modification. I will also offer this tool for rental here on DSO for fellow members wanting to go with larger head studs, as a sad attempt to recoup my own costs of buying this kit lmao. I will post up a link to the thread I will add to offer the rental and conditions. This is what the kit looks like:
3. Modifying Cylinder Head Bolt/Stud Passthrough Holes
The cylinder head passthrough holes will need to be enlarged to properly clear the wider diameter of the head studs, these guys:
Choose the smallest possible drill bit that goes slightly larger than the stud, and I would spring the cash to buy this drill bit brand new so it cuts cleanly, and not use the worn out bits from the general set of bits in your toolbox
Jvtec8k used a 29/64" bit.
Tape off the machined surface around the holes on the block facing side of the head to prevent damage to head surface.
Drill from the valve cover side of the head, down to the block side, to keep potential damage to the head surface as minimal as possible.
Drill STRAIGHT and SLOWLY, trying to keep from cutting off center and removing too much material.
Make sure to lightly touch a deburring tool to the ends of the holes in the block side of the cylinder head after drilling, to remove any burrs and/or to lower any raised spots of aluminum that might have been pushed outward due to drilling.
4. Modifying Head Gasket Bolt/Stud Passthrough Holes
This process is the same as above for the cylinder head, but now you need to use the same drill bit, and drill out the stud/bolt holes in the head gasket to accept the larger stud diameter.
Put painters tape across the gasket surfaces top and bottom to prevent knicking any of the Viton sealant if using an MLS gasket. This is just good practice, regardless of the gasket material.
It is CRITICAL to verify that there are NO burrs or shavings that fall between the MLS inner layers! Take your time here and verify that there are no burrs around these drilled holes. Compressed air and a flashlight is your friend.
Remove burrs around the drilled holes lightly using a deburring tool if needed.
Reassemble and torque studs according to the ARP kit instructions you decided to go with to accomplish this.
Thanks,
Talon.