Ap1 to S2000 AP2 Retainer, Valve Spring and S2000 Retainer Keepers
06-17-2019, 04:17 PM
#11
Again, my point is that this is a personal decision that each individual has to make. Both F20 and F22 retainers/cotters are available from Honda so clearly Honda never felt there was a need to pull the F20 retainers/cotters from the shelves. When I read the Honda bulletin, it's warning is NOT to MIX the different parts numbers, as they are NOT interchangeable. It also references that engine numbers are provided so as to ensure ordering the correct parts. However, it never states that the F20 parts are defective and should be removed from inventory. As Billman250 pointed out, Honda made changes with the F22 to help minimize the chances of a retainer failure by increasing mass/strength of the retainers and by making slight changes to the cotters. Honda also lowered redline but increased displacement of the engine, presumably to keep the horsepower at the original number while increasing mid-range torque to make the car feel like it had more oomph under normal driving conditions.
The part I am still not understanding is that when Honda incorporated these changes in the F22, they made these changes to both intake and exhaust sides of the head. If Honda felt that increasing the mass/strength of the exhaust side retainers would somehow compromise the exhaust side of the system, then it seems like Honda would have left the F20 retainers/cotters on the exhaust side while beefing up the intake side with the new parts. But Honda didn't do that, they made these changes to both sides of the head.
So to me, my feeling is that if you are going to upgrade your retainers/cotters to the the F22 parts, then I personally would do both sides as this is what Honda did. Otherwise, you now have a "hybrid system" that Honda never engineered. I'm sure there is plenty of smart folk who can provide theories as to why this is, but I'm following Honda's lead and upgraded the entire retainer/cotter system to the F22 parts. The seats are the same across the board, so Honda didn't feel a need to change the seats. The springs do have different part numbers between F20 and F22, but I'm assuming that's a vendor change rather than a spec change (NHk in the F20 and Nippon in the F22).
Here is a screen shot of the parts I ordered when I did my swap to F22 parts, to show I completely changed out the correct parts and didn't interchange any parts, as per Honda's recommendation.
The part I am still not understanding is that when Honda incorporated these changes in the F22, they made these changes to both intake and exhaust sides of the head. If Honda felt that increasing the mass/strength of the exhaust side retainers would somehow compromise the exhaust side of the system, then it seems like Honda would have left the F20 retainers/cotters on the exhaust side while beefing up the intake side with the new parts. But Honda didn't do that, they made these changes to both sides of the head.
So to me, my feeling is that if you are going to upgrade your retainers/cotters to the the F22 parts, then I personally would do both sides as this is what Honda did. Otherwise, you now have a "hybrid system" that Honda never engineered. I'm sure there is plenty of smart folk who can provide theories as to why this is, but I'm following Honda's lead and upgraded the entire retainer/cotter system to the F22 parts. The seats are the same across the board, so Honda didn't feel a need to change the seats. The springs do have different part numbers between F20 and F22, but I'm assuming that's a vendor change rather than a spec change (NHk in the F20 and Nippon in the F22).
Here is a screen shot of the parts I ordered when I did my swap to F22 parts, to show I completely changed out the correct parts and didn't interchange any parts, as per Honda's recommendation.
If I understand your logic correctly then you're stating Honda did it this way - therefore it is the correct way. Honda did not advise swapping the original AP1 retainers out (did they? If so where is this guidance). As you state they're not defective, so surely you are going against Honda in the first instance.
06-17-2019, 07:48 PM
#12
Sigh. Fine: Doing the intake side is a personal decision on whether to reduce the risk of damage in an overrev; doing the exhaust side is a personal decision on whether to increase that risk.
I'll try once more to lay out the facts and the logic.
Fact: The F20 retainers are easily sufficient for normal operation, up to 9k rpm. We know this because even hard-driven F20 motors do not exhibit retainer cracks if they are not overrevved. You can, if you wish, ride the limiter all day without fear of cracked retainers. The ONLY purpose of this swap is to get some extra margin if you f@#! up a shift and mechanically spin the motor beyond 9k rpm. That's why Honda never changed the parts: missed shifts aren't covered under any warranty (nor should they be).
Fact: The F20 retainers are the first things damaged in a mechanical overrev, and therefore are the limiting factor in terms of rev margin. The intake retainers crack at about 10k rpm, so that's the effective limit. True, they don't generally fail catastrophically during the overrev event, but once they crack they are a time bomb. Eventually, even if the motor is never overrevved again, a retainer WILL fail, the valve will drop, and the motor will be lost. We know all this because we've seen it time and time again.
Fact: The exhaust retainers (identical to intake) are not as highly stressed as the intake retainers, due to softer valve springs and smaller/lighter valves. They have essentially never been observed to crack, even when the intake retainers are badly damaged (the only known instances involved motors that showed evidence of previous head work).
Fact: In an extreme overrev event, it is NOT the intake valves that first contact the piston, it is the exhaust valves. Therefore exhaust valve float is the next limiting factor, after cracking intake valves. Valve-piston contact occurs around 10,700 rpm.
Fact: All else equal, the amount of valve float depends on the mass of the valve and retainer, which have to be moved by the spring.
Conclusion: If the intake retainers could be prevented from cracking, the F20 could survive an overrev up to 10,700 rpm, i.e. about 700 rpm higher than with the stock F20 retainers. In fact, to my knowledge we've never seen a dropped-valve failure on an F20 that uses F22 retainers on the intake.
Conclusion: Since the F22 retainer is slightly heavier than the F20 retainer, it is unavoidable that the exhaust-valve-float rev limit will be lower with F22 retainers than with F20 retainers. How much lower? 50 rpm? 100? 500? We don't actually know, since most people don't ignore Billman's advice.
It's probably not much, but it seems perverse to try to find out.
I'll try once more to lay out the facts and the logic.
Fact: The F20 retainers are easily sufficient for normal operation, up to 9k rpm. We know this because even hard-driven F20 motors do not exhibit retainer cracks if they are not overrevved. You can, if you wish, ride the limiter all day without fear of cracked retainers. The ONLY purpose of this swap is to get some extra margin if you f@#! up a shift and mechanically spin the motor beyond 9k rpm. That's why Honda never changed the parts: missed shifts aren't covered under any warranty (nor should they be).
Fact: The F20 retainers are the first things damaged in a mechanical overrev, and therefore are the limiting factor in terms of rev margin. The intake retainers crack at about 10k rpm, so that's the effective limit. True, they don't generally fail catastrophically during the overrev event, but once they crack they are a time bomb. Eventually, even if the motor is never overrevved again, a retainer WILL fail, the valve will drop, and the motor will be lost. We know all this because we've seen it time and time again.
Fact: The exhaust retainers (identical to intake) are not as highly stressed as the intake retainers, due to softer valve springs and smaller/lighter valves. They have essentially never been observed to crack, even when the intake retainers are badly damaged (the only known instances involved motors that showed evidence of previous head work).
Fact: In an extreme overrev event, it is NOT the intake valves that first contact the piston, it is the exhaust valves. Therefore exhaust valve float is the next limiting factor, after cracking intake valves. Valve-piston contact occurs around 10,700 rpm.
Fact: All else equal, the amount of valve float depends on the mass of the valve and retainer, which have to be moved by the spring.
Conclusion: If the intake retainers could be prevented from cracking, the F20 could survive an overrev up to 10,700 rpm, i.e. about 700 rpm higher than with the stock F20 retainers. In fact, to my knowledge we've never seen a dropped-valve failure on an F20 that uses F22 retainers on the intake.
Conclusion: Since the F22 retainer is slightly heavier than the F20 retainer, it is unavoidable that the exhaust-valve-float rev limit will be lower with F22 retainers than with F20 retainers. How much lower? 50 rpm? 100? 500? We don't actually know, since most people don't ignore Billman's advice.
It's probably not much, but it seems perverse to try to find out.
06-17-2019, 08:13 PM
#13
Correct, Honda never advised using F22 retainers/cotters on an F20 motor, that I am aware of. Therefore, anyone putting any F22 retainers/cotters on a F20 is therefore violating anything Honda ever intended with these motors. I think we can all agree on that observation/conclusion? As also stated, Honda doesn't cover mechanical over-revs under warranty and clearly the original design was never thought to be an issue, even after this "problem" first surfaced almost two decades ago. Or else they would have discontinued those parts and replace them with the F22 retainers/cotters, yes?
Therefore, anyone willing to venture beyond the OEM realm of engineering is doing so at their own risk, correct? I am not a professional race car builder or professional mechanic. I am not an automotive engineer. I do come from an aviation background with almost two decades of being involved with aircraft maintenance operations. So the first thing I looked at, when comparing the F20 to F22 heads, was what parts remained the same and what Honda changed. As far as I can tell, the only parts they changed in the head were the retainers/cotters. They also put these new retainers/cotters on the both the intake/exhaust side. So I'm pretty confident the engineers at Honda took all these issues into consideration and were confident in the decision(s) they made.
Since we are all in agreement that anyone putting F22 retainers/cotters is venturing outside of Honda's engineering guidance, then we can all agree that it becomes a "use at your own risk" proposition correct? I am willing to take that risk, just to hopefully provide a little extra insurance on a missed shift at high RPMs. I also feel comfortable doing both intake/exhaust, because that's what Honda did when they "revised" the F22 head. I would rather follow Honda, than create my own "hybrid" head and then try and claim that I know better than the OEM.
I put forth my personal reasons why I chose this route so people could make their own informed decision looking at the logic and reasoning behind my thought process. Everyone certainly has a right to their own opinions and in the end, it's your own toy so use it how ever you wish. Has anyone running F22 retainers/cotters on both intake/exhaust on an F20 had any known problems?
Cheers!
Therefore, anyone willing to venture beyond the OEM realm of engineering is doing so at their own risk, correct? I am not a professional race car builder or professional mechanic. I am not an automotive engineer. I do come from an aviation background with almost two decades of being involved with aircraft maintenance operations. So the first thing I looked at, when comparing the F20 to F22 heads, was what parts remained the same and what Honda changed. As far as I can tell, the only parts they changed in the head were the retainers/cotters. They also put these new retainers/cotters on the both the intake/exhaust side. So I'm pretty confident the engineers at Honda took all these issues into consideration and were confident in the decision(s) they made.
Since we are all in agreement that anyone putting F22 retainers/cotters is venturing outside of Honda's engineering guidance, then we can all agree that it becomes a "use at your own risk" proposition correct? I am willing to take that risk, just to hopefully provide a little extra insurance on a missed shift at high RPMs. I also feel comfortable doing both intake/exhaust, because that's what Honda did when they "revised" the F22 head. I would rather follow Honda, than create my own "hybrid" head and then try and claim that I know better than the OEM.
I put forth my personal reasons why I chose this route so people could make their own informed decision looking at the logic and reasoning behind my thought process. Everyone certainly has a right to their own opinions and in the end, it's your own toy so use it how ever you wish. Has anyone running F22 retainers/cotters on both intake/exhaust on an F20 had any known problems?
Cheers!
06-17-2019, 11:08 PM
#14
Registered User
For your information, in Europe we don't have AP2. From 2004 and after, the facelift S2000 AP1 still has the F20C engine, but it has been upgraded with the AP2 evolutions such as the news PCV valve and the AP2 retainers.
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CH53Driver (06-18-2019)
06-18-2019, 05:10 AM
#15
Good point, I had not thought about the F20 getting those revisions in the non-North American market. So basically, Honda did include those changes on 2004+ F20 engines, which means I followed suit by making the same changes to the head that Honda did. Thanks for pointing that out!
06-18-2019, 03:10 PM
#16
Good point, I had not thought about the F20 getting those revisions in the non-North American market. So basically, Honda did include those changes on 2004+ F20 engines, which means I followed suit by making the same changes to the head that Honda did. Thanks for pointing that out!
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twohoos (06-20-2019)
06-20-2019, 04:16 AM
#17
My personal decision is to follow Billman's advice. Inspect intake side retainers. If signs of cracking are present, replace the intake side retainers and keepers with ap2 parts. Do not change out the exhaust side. If no signs of cracking, leave original ap1 retainers and keepers alone. If you have an over-rev event, inspect and proceed accordingly.
I can't provide links, but there are a number of threads floating around here in which folks changed out their retainers with ap2 parts without any signs of cracking as a form of "preventive maintenance," and they have ended up creating all sorts of troubles for themselves. In my opinion this is a situation where the old adage "if it ain't broke don't fix it" is the best approach. Unless you have signs of cracking on inspection, leave the car alone. Other's apparently see this differently. I guess that is what makes the world go around.
I can't provide links, but there are a number of threads floating around here in which folks changed out their retainers with ap2 parts without any signs of cracking as a form of "preventive maintenance," and they have ended up creating all sorts of troubles for themselves. In my opinion this is a situation where the old adage "if it ain't broke don't fix it" is the best approach. Unless you have signs of cracking on inspection, leave the car alone. Other's apparently see this differently. I guess that is what makes the world go around.
Last edited by rpg51; 06-20-2019 at 04:19 AM.
06-15-2020, 07:50 PM
#18
Registered User
My personal decision is to follow Billman's advice. Inspect intake side retainers. If signs of cracking are present, replace the intake side retainers and keepers with ap2 parts. Do not change out the exhaust side. If no signs of cracking, leave original ap1 retainers and keepers alone. If you have an over-rev event, inspect and proceed accordingly.
I can't provide links, but there are a number of threads floating around here in which folks changed out their retainers with ap2 parts without any signs of cracking as a form of "preventive maintenance," and they have ended up creating all sorts of troubles for themselves. In my opinion this is a situation where the old adage "if it ain't broke don't fix it" is the best approach. Unless you have signs of cracking on inspection, leave the car alone. Other's apparently see this differently. I guess that is what makes the world go around.
I can't provide links, but there are a number of threads floating around here in which folks changed out their retainers with ap2 parts without any signs of cracking as a form of "preventive maintenance," and they have ended up creating all sorts of troubles for themselves. In my opinion this is a situation where the old adage "if it ain't broke don't fix it" is the best approach. Unless you have signs of cracking on inspection, leave the car alone. Other's apparently see this differently. I guess that is what makes the world go around.
06-16-2020, 01:23 AM
#19
You can inspect from top. If the retainers are in good shape the keepers sit just about flush with the top surface of the retainers. If the retainers are cracked the keepers sit lower than top surface of the retainers. They look slightly sunken into the retainers. Somewhere here, or in another thread on this topic, there are some good pictures of this.
