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Discussion Starter · #1 ·
Installing Toda cams and valve springs in a K24A and ran into an issue. Toda says that stock retainers are fine but they appear to be small and looks pretty sketchy.

Installed to test and left is Toda valve spring with stock retainer and right is stock spring and retainer.

It looks wrong to me...has anyone else run into this issue?
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This is for a gravel rally Civic

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Installing Toda cams and valve springs in a K24A and ran into an issue. Toda says that stock retainers are fine but they appear to be small and looks pretty sketchy.

Installed to test and left is Toda valve spring with stock retainer and right is stock spring and retainer.

It looks wrong to me...has anyone else run into this issue? View attachment 105470

This is for a gravel rally Civic

View attachment 105471
What does the intake setup /ducting look like if there is any?
 

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These don鈥檛 look like k20a2 OEM retainers to me.
Seems like you k24 uses something different.
Here is a recent picture from my head with Toda springs and all OE retainers.

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These don鈥檛 look like k20a2 OEM retainers to me.
I totally agree with you @Lotus. I have investigated the ports and valves of the PRB, RBB, PPA and RSP head. None of them using flat retainers. There are differences in diameter, so that valve springs are not interchangeable. I have no clear statement to which one, just remember the PPA was smaller. Not sure if the RBB was it also to the high performance head retainers.
 

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Discussion Starter · #9 · (Edited)
Thanks all...it appears the K24A OEM is a single spring with a smaller diameter retainer. Any recommendation on aftermarket retainers or just run a OEM part number 14765-PRB-A01 with 14781-PRB-A02 locks? I likely need to change the spring seat too.

BTW...ditching the JRSC and just going NA since all we need is 240whp for gravel.

Andrew
 

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Thanks all...it appears the K24A OEM is a single spring with a smaller diameter retainer. Any recommendation on aftermarket retainers or just run a OEM part number 14765-PRB-A01 with 14781-PRB-A02 locks? I likely need to change the spring seat too.

BTW...ditching the JRSC and just going NA since all we need is 240whp for gravel.

Andrew
Same thing that I have so this is some good info 馃憤
 

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Discussion Starter · #13 ·
Thanks all...it appears the K24A OEM is a single spring with a smaller diameter retainer. Any recommendation on aftermarket retainers or just run a OEM part number 14765-PRB-A01 with 14781-PRB-A02 locks? I likely need to change the spring seat too.

BTW...ditching the JRSC and just going NA since all we need is 240whp for gravel.

Andrew
Following up on this as it seems that Acura/Honda is out of stock on new 14781-PRB-A02 locks, and backordered indefinitely. Therefore, I will likely need to run aftermarket retainers and locks and leaning toward SuperTech steel retainers and matching locks. Does anyone know if this will change the valve height/seat pressure as compared to the stock dual spring set up?
 

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Height is dictated by the valve and not the spring.
Seat pressure will be higher with the Toda springs compared to stock, but likely lighter than Supertech double springs.

The K24 will extend its powerband with the JRSC even at very low boost. It鈥榣l climb to wherever you set the limiter. do you have any class restrictions?
Which Toda did you get?

My CT-E SC (also Eaton MP62) does not work well with the Toda A3 on my K20 build. It severely lacks torque independed of VTC angle and boost is low. It likely suffers blow-through. For next season, I drop in the k20a2 stock cams or go back to NA and the RBC intake manifold.
 

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Discussion Starter · #15 ·
Height is dictated by the valve and not the spring.
Seat pressure will be higher with the Toda springs compared to stock, but likely lighter than Supertech double springs.

The K24 will extend its powerband with the JRSC even at very low boost. It鈥榣l climb to wherever you set the limiter. do you have any class restrictions?
Which Toda did you get?

My CT-E SC (also Eaton MP62) does not work well with the Toda A3 on my K20 build. It severely lacks torque independed of VTC angle and boost is low. It likely suffers blow-through. For next season, I drop in the k20a2 stock cams or go back to NA and the RBC intake manifold.
I am removing the blower and just going N/A since we were only using 3lbs of boost, didn't seem worth the weight and heat. No class rules, but anything over 250whp in a 2200lb fwd car on gravel is pointless.

I went with Toda C's
 

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Toda C on a K24 should make a very nice NA engine. Did you fit forged pistons and steel rods or are you running a stock bottom end? If the latter, don't overdo it with the rev limit.

a 3 PSI it won't generate a lot of heat, but the VE won't drop no mater how high you rev the engine. It is a very nice combo despite the low boost. It will easily get you over 250wHp. I am not so sure on Toda C plus supercharging. So overall sounds like a good idea to start off as NA first.
 

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Discussion Starter · #17 ·
Toda C on a K24 should make a very nice NA engine. Did you fit forged pistons and steel rods or are you running a stock bottom end? If the latter, don't overdo it with the rev limit.

a 3 PSI it won't generate a lot of heat, but the VE won't drop no mater how high you rev the engine. It is a very nice combo despite the low boost. It will easily get you over 250wHp. I am not so sure on Toda C plus supercharging. So overall sounds like a good idea to start off as NA first.
Rev limited is set at 7800...bottom end is stock and only internal change is cams and fixed 35 VTC gear. Car is tuned via AEM ecu.
 

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Jeff Cooper in the UK got about 280 crank HP and 214 lbs ft out of his K24 NA with cams and RBC intake and 330bhp and 222lbs ft torque with the JRSC.
It just did not last long reving it to 8k with a stock bottom end.

Gains with the SC were mainly up to 5000 and post 7000 rpm.






Check out his videos. He build a dry sumped K20 caterham on ITBs and the like.
 

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Discussion Starter · #19 ·
Jeff Cooper in the UK got about 280 crank HP and 214 lbs ft out of his K24 NA with cams and RBC intake and 330bhp and 222lbs ft torque with the JRSC.
It just did not last long reving it to 8k with a stock bottom end.

Gains with the SC were mainly up to 5000 and post 7000 rpm.






Check out his videos. He build a dry sumped K20 caterham on ITBs and the like.
Thanks - I did lose the previous motor (overheated but that may have been from something else), maybe spinning it too high? I think there's not much to gain after 7600 anyway, just top speed with the short gearing.
 

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average piston speed at 7800 is 25.74 m/s. That is F1-level on a cast piston.
For a rally application on cast pistons and rods, I'd stick to something like 7200 to 7300 . That corresponds to the piston speed of a K20 spinning about 8300 or 23.8 m/s.
That is near stock, but it will last. Make it 7500, but not higher on a stock bottom end.

Joe McCarthy once posted here 2013 about the K20a that is essentially using the same rod and piston technology.
"I'm basing that bit of advice on many years of experience of endurance racing stock bottom end K20's in the 25 hour at Thunderhill. If the rev limiter is set at 8,200-8,300 the engine will finish the race without exception. If its set at 8,600 one of the pistons will disintegrate by the 11-12 hour mark. At 9,200 I've seen stock pistons last under 10 laps. I can't even begin to count how many times I've seen people destroy perfectly good engines by doing this. I've also seen engines limited to 8,300 last through 2 complete seasons of endurance racing, which is about 100 hours total.
Its metal fatigue, which has 2 components, load and time. That's what determines the lifespan of any metallic part.
On the street the time span is SO short that a lot of people get away with over revving the engine for a long time, but its just a clock ticking off the seconds at that load level and eventually the piston WILL be destroyed."
 
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