86 CRX SI K24a swap
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Got the motor work done today. RBC 50 deg VTC, Type S oil pump, unit 2 barreled pan and a few other small items.
We discovered my alternator will not work with the KTuned relocation kit. Brian is going tomorrow to check his inventory to see if he has one that will work. The issue is the provided replacement pulley hits the housing and won’t turn.
then we are modifying one of the bolts on the kit from 8mm to 10. This is the long bolt used in the kit and Brian has seen them break under conditions like racing. Means water pump housing must be drilled and tapped and the alternator bolt hole must be opened up.
If he finds one we are going to try and do these modifications tomorrow and get that on the motor.
We discovered my alternator will not work with the KTuned relocation kit. Brian is going tomorrow to check his inventory to see if he has one that will work. The issue is the provided replacement pulley hits the housing and won’t turn.
then we are modifying one of the bolts on the kit from 8mm to 10. This is the long bolt used in the kit and Brian has seen them break under conditions like racing. Means water pump housing must be drilled and tapped and the alternator bolt hole must be opened up.
If he finds one we are going to try and do these modifications tomorrow and get that on the motor.
why not just go up to a 12.9 grade bolt while maintaining the normal torque of this bolt. They are way stronger. Bolt breakage commonly occurs if bolt tension is too low letting the bolt experiencing cyclic loads.
The CT-E superchargers had issues with bolt brake on their alternator relocation. This got solved with 12.9 grade bolts. Some replaced the brackets with steel parts vs the original aluminium. Although I think the breakage was caused by a first bolt braking leading to the entire load being transferred to the second bolt hole and bracket half.
The CT-E superchargers had issues with bolt brake on their alternator relocation. This got solved with 12.9 grade bolts. Some replaced the brackets with steel parts vs the original aluminium. Although I think the breakage was caused by a first bolt braking leading to the entire load being transferred to the second bolt hole and bracket half.
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KTuned upgraded also from there last bolt spec to 12.9 grade bolts, which is a complete mismatch regarding torque demand of the bolt and the torque capability of the alu of the block. We discussed this in the KTuned ACPS delete thread. You need to glue the thread and solve a symptom by creating another issue, while bolts still brake. Less often, but still they brake. A better solution is always to understand the load profile of the application and design the bracket accordingly. More to the system load and solution you may find here: K-tuned alternator bolt breaking? | Honda / Acura K20a K24a Engine Forum
This “solution” indicates to me a loss of clamping over time and a resulting bending and shear load on the bolt or a case that is to weak to begin with for the loads.
Could be that the alternator casing around the bolt holes are not stiff enough to take all the loads of the alternator forces. This means the bolt is always participating in the cycling loading. If these brackets wouod be thicker and stronger, the bolt would only ever see its clamping forces and no dynamic forces.
As is it seems the bolts participate in the cyclic loading. Although @Lotus has a far better understanding on these topics as a ME compared to me as a chemist.
The alternator bolts experience a lot of cycling loads to to the secondary inbalance of the engine moving it up and down a twice the rotational frequency. Many k20a2 alternator split their cases over time. An other indicator of the cyclic loads.
The alternator acts like a pendulum on the block.
As stiffness and with it strength increase with the cube of the thickness, going from 8mm to 10mm bolt doubles the strength while goind from 8.8 to 12.9 you gain more like a 30%.
Could be that the alternator casing around the bolt holes are not stiff enough to take all the loads of the alternator forces. This means the bolt is always participating in the cycling loading. If these brackets wouod be thicker and stronger, the bolt would only ever see its clamping forces and no dynamic forces.
As is it seems the bolts participate in the cyclic loading. Although @Lotus has a far better understanding on these topics as a ME compared to me as a chemist.
The alternator bolts experience a lot of cycling loads to to the secondary inbalance of the engine moving it up and down a twice the rotational frequency. Many k20a2 alternator split their cases over time. An other indicator of the cyclic loads.
The alternator acts like a pendulum on the block.
As stiffness and with it strength increase with the cube of the thickness, going from 8mm to 10mm bolt doubles the strength while goind from 8.8 to 12.9 you gain more like a 30%.
I agree. I bought an aftermarket TB. I also bought new OEM IACV, KTuned TPS, OEM map sensor, OEM purge valve. I am sending off the OEM TB to maxbore to bore it to 65mm. incase the 70mm TB fails performance I can swithc it all over to the OEM cable TB.
Do you know if anyone has ever tried to swap the entire inner assembly into an aftermarket housing? swap spring, plate shaft, etc..?
On my former K22 stroker I want from a S90 70mm TB to a J's racing 65mm TB and found no difference in MAP over rpm between the two that was larger than the general fluctuation across a single run. We talk a few mbar here or power differences on the order of <1HP.
Once you see full MAP post 60% TPS you know a TB is too big,
But drivability is SOOO much better with the OEM TB and it never sticks or causes any other issues.
Once you see full MAP post 60% TPS you know a TB is too big,
But drivability is SOOO much better with the OEM TB and it never sticks or causes any other issues.
this is what I was assuming you would say. Something I found interesting that I took from the owner at Hybrid Racing, we find it hard to expect a customer to pay $500-$600 for a throttle body. That is how much they need to get for them in order to sell them. Just like you just said Lotus, the quality of the OEM unit is hard to pass up. I think Hybrid Racing is the only one who has produced something close to OEM in aftermarket sizing. I would pay $600 for a quality TB.
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Great info. Brain said he also things it’s a byproduct of over tightening of the belt which would impart leverage on the alternator and that bolt. We are planning on working on it tomorrow night. At point now where there are just a few items to do on the motor and we need to clean and prep the bay.
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Not only this. I am not sure if you ever run a bycicle tire only on one side of the axis in your hand. That force and leverarm keeping the axis, while the tire is rotating, still in horizontal position despite only one side is hold by your hand also is able to brake bolts. This force and lever arm = torque don't like to be moved, it works against the change of position. If your rotating alternator (racing = higher engine speed = higher alternator speed) see all the bumping in any direction and really fast this puts enormous forces on the brackets of the alternator and if the fixation is under-designed (calculated to low) then the repeated cycle fatigue kills the fixation bolts. It's not a question of bolt tension capability, its a question of friction and clamping force of the bolt. This is defined by the alu and not the bolt. Any bolt can brake in that situation. It is simple not well engineered and can not be solved with an higher bolt grade. The solution is to offer a more stable and more strong bracket and more clamping points, that's all. The thread I've mentioned offers different solutions on that.
There is a good reason to prevent from 12.9 bolts in oscillating products, they are brittle. If the clamping force is to low because the thread can't provide it, they suffer hard from non-axial acceleration forces.
There is a good reason to prevent from 12.9 bolts in oscillating products, they are brittle. If the clamping force is to low because the thread can't provide it, they suffer hard from non-axial acceleration forces.
on the other side, the 8.8 bolt stretch, bending or pull won't matter, way earlier than the 12.9 losing even more clamping force. And that loss of clamping force increases the forces going through the bolt as the alloy won't do much without clamping. This leads to the bolt braking. It is a run-away process. Lotus Elise OEM rear toe-links are known for this.
The 12.9 will resist that stretch for longer.
In the toe link application, the solution is to switch to a double shear arrangement essentially removing the bending forces from the bolt. Even if clamping is lost, in double shear the bolt can take a lot of force before failure.
Going for 10mm on the alternator is essentially a measure to pretty much only use the bolt as the load bearing structure and use the alloy as a mere sleeve to increase bending stiffness. The bolt itself will provide most of the stability and not the alloy post anymore.
Engines running balancing shafts will suffer less from this issue. Fine balancing the rotating assembly also reduces vibrations.
The 12.9 will resist that stretch for longer.
In the toe link application, the solution is to switch to a double shear arrangement essentially removing the bending forces from the bolt. Even if clamping is lost, in double shear the bolt can take a lot of force before failure.
Going for 10mm on the alternator is essentially a measure to pretty much only use the bolt as the load bearing structure and use the alloy as a mere sleeve to increase bending stiffness. The bolt itself will provide most of the stability and not the alloy post anymore.
Engines running balancing shafts will suffer less from this issue. Fine balancing the rotating assembly also reduces vibrations.
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We got the K Tuned relocation kit installed and also increased the size of the bolt from the 8mm included to 10mm. we also noticed the bolt does not go into the water pump housing very deep so we are going to source a 120mm instead of the included 110mm length.
changed a few other things today. RDX thermostat so the outlet points down instead of up and a modified TSX water manifold. The one on the JDM K24a has a provision the EGR and is much larger. This one has the heater water port welded shut, since I do not use the heater. Water temp sensor installed and the block bracket for the passenger side mount.
didn’t get as far as we hoped du to the work on the K Tuned kit and alternator. Next we will get the motor off the stand and put the flywheel, clutch and trans together so it’s ready to go into the car.
changed a few other things today. RDX thermostat so the outlet points down instead of up and a modified TSX water manifold. The one on the JDM K24a has a provision the EGR and is much larger. This one has the heater water port welded shut, since I do not use the heater. Water temp sensor installed and the block bracket for the passenger side mount.
didn’t get as far as we hoped du to the work on the K Tuned kit and alternator. Next we will get the motor off the stand and put the flywheel, clutch and trans together so it’s ready to go into the car.
Joined
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150 Posts
We worked on the motor again last night, simplest things fought us causing it to take longer than it should.
we made final mods to the K Tuned relocation kit so that all went together better. Still do not have the correct alternator so working on that in the meantime.
got the flywheel and clutch installed then mated the trans to the motor. We then prepped the trans for the mounts. Had to remove the OEM studs and that was a battle. One came out okay and the other was a mess. Also had to chase threads due to buildup inside them and studs being damaged.
we are at a point where the motor is ready to go in. We did find the cable speedometer assembly will not fit in a K Series transmission. They are very different and so we are going to have to find another option. I have an extra cluster we are going to use to see if an electric speedo assemble can be placed inside of the cluster. Working speedometer is a nice thing to have unless your a full race car.
we hope to work on it Saturday afternoon. Brian is getting the radiator ready and we will cut the lump off the passenger frame rail so the mounts can go in.
we made final mods to the K Tuned relocation kit so that all went together better. Still do not have the correct alternator so working on that in the meantime.
got the flywheel and clutch installed then mated the trans to the motor. We then prepped the trans for the mounts. Had to remove the OEM studs and that was a battle. One came out okay and the other was a mess. Also had to chase threads due to buildup inside them and studs being damaged.
we are at a point where the motor is ready to go in. We did find the cable speedometer assembly will not fit in a K Series transmission. They are very different and so we are going to have to find another option. I have an extra cluster we are going to use to see if an electric speedo assemble can be placed inside of the cluster. Working speedometer is a nice thing to have unless your a full race car.
we hope to work on it Saturday afternoon. Brian is getting the radiator ready and we will cut the lump off the passenger frame rail so the mounts can go in.
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