KM steel rocker arms - M20

[bangn]

heya,

does anyone have exposure to the KM steel rocker arms for M20? Interested to hear if you had any negative effects regards to lift, nose pressure, revving, noise, wear??
I also have billet ally rocker locks so also wondering if they will flog out a groove in them.

[82eye]

no exposure to them, but what do you want to build ?

i got hd rockers through BimmerHeads, but i believe they may have been IE sourced. i put them in when i did engine work mostly as a while i'm there thing. kept the original rockers. i got the head cleaned up and had the cam reground.

[bangn]

In a perfect world I wanted the bimmerheads HD rocker arms, but unfortunately they're on backorder with no eta. Not really keen on the IE arms as they seem pretty risky given they have ramp issues. As far as I was aware BH sourced their own?

Strength wise I guess the steels would be a no brainer but worried about that extra weight. I've researched as much as I can about them but there really isn't a lot of info out there.

I am building a 2.9 turbo, have pretty much everything other than valve springs and rocker arms now. Rev limit I wanted 7500 but might be a 7000 limit If the rocker arms are steel. Its a street vehicle that gets driven for maybe a couple of hours a month if its lucky.

[digger]

I have a sample here and the profile does not match the factory rocker so who knows what effect this has on the valve motion.

[It's Soda Not Pop]

In a perfect world I wanted the bimmerheads HD rocker arms, but unfortunately they're on backorder with no eta. Not really keen on the IE arms as they seem pretty risky given they have ramp issues. As far as I was aware BH sourced their own?

Strength wise I guess the steels would be a no brainer but worried about that extra weight. I've researched as much as I can about them but there really isn't a lot of info out there.

I am building a 2.9 turbo, have pretty much everything other than valve springs and rocker arms now. Rev limit I wanted 7500 but might be a 7000 limit If the rocker arms are steel. Its a street vehicle that gets driven for maybe a couple of hours a month if its lucky.

Have you contacted Bimmerheads to see if they can give you the insight on them?

[bangn]

Yeh, they advised alot of high hp m20 owners use them and they advise a limit of 6800-7000. I have asked some follow up questions but just ensuring no info is left on the table so theres no surprises.

Thats a bit concerning digger, have you ever done testing with them to see if they reduce or increase lift?

[digger]

Yeh, they advised alot of high hp m20 owners use them and they advise a limit of 6800-7000. I have asked some follow up questions but just ensuring no info is left on the table so theres no surprises.

Thats a bit concerning digger, have you ever done testing with them to see if they reduce or increase lift?

I looked briefly at it and there was a reduction in lift if I recall but I only did limit measurement and it must have been like at least 8 years ago

I would look at the cat cams rockers but they are much more expensive though.

[82eye]

In a perfect world I wanted the bimmerheads HD rocker arms, but unfortunately they're on backorder with no eta. Not really keen on the IE arms as they seem pretty risky given they have ramp issues. As far as I was aware BH sourced their own?

i'm pretty certain they are the same as IE. i got them a while ago, they may have changed suppliers. they don't build that stuff themselves. the long tube header is IE sourced as well.

there's not a pile of difference between them and normal rockers. they are peened and a bit thicker on the adjuster side.

I am building a 2.9 turbo, have pretty much everything other than valve springs and rocker arms now. Rev limit I wanted 7500 but might be a 7000 limit If the rocker arms are steel. Its a street vehicle that gets driven for maybe a couple of hours a month if its lucky.

i'm pretty sure they have a rev limit at 7000. they are more for a car that would see 7k on occasion, not one that lives there constant.

[hasa]

So you say that turbo engine can't live with properly chosen and shimmed valve springs and std rockers like N/A engines?

[82eye]

So you say that turbo engine can't live with properly chosen and shimmed valve springs and std rockers like N/A engines?

the original rockers fail all the time on stock motors. it's a good idea if you add cam or power to go with a heavier set.

[digger]

In a perfect world I wanted the bimmerheads HD rocker arms, but unfortunately they're on backorder with no eta. Not really keen on the IE arms as they seem pretty risky given they have ramp issues. As far as I was aware BH sourced their own?
.

They are the same

[bangn]

They are the same

bugger! cheers for the suggestion on the catcams, that's one I wasn't aware of. Ive flicked them a message to see what stock/pricing is like.. im guessing they will be near on double of the KM's.

[hasa]

the original rockers fail all the time on stock motors. it's a good idea if you add cam or power to go with a heavier set.

You did not answer to my question, but anyway.

I have a theory that valve springs are the key components to success. But I can’t prove it.

Of course anti-lag systems and hitting limiter with turbo engine are harder to cope. Required spring forces may simply be too heavy for stock rocker physical properties.

[varg]

I don't see a compelling reason to upgrade the rockers when turbocharging unless you've increased cam profile aggressiveness or spring pressure significantly. A turbo doesn't necessarily stress them any more than being stock, it's only the abuse that usually comes with turbocharging. Think about the increases in forces involved; boost pushes down on the valves, exhaust stroke pressure on the face of the valve while open is negligible, increased heat doesn't reach the rockers. If you don't abuse your engine, (i.e. race use, drifting, bouncing off the rev limiter, revving past your power peak) I don't see them being an issue any more than stock. When I had ForcedFirebird rebuild my M20 head, he used resurfaced OEM rockers, I leaned on his spec E30/Chump car race experience to tell me that I was better off using inspected and surfaced OE rockers than buying IE HD. FWIW I have a 272° cam and my limiter is set to 6700rpm. I don't abuse my engine, I probably only hit the rev limiter a few times per month, I usually shift right at 6,500-6,600rpm if I rev it out.

[82eye]

I don't see a compelling reason to upgrade the rockers when turbocharging unless you've increased cam profile aggressiveness or spring pressure significantly. A turbo doesn't necessarily stress them any more than being stock, it's only the abuse that usually comes with turbocharging. Think about the increases in forces involved; boost pushes down on the valves, exhaust stroke pressure on the face of the valve while open is negligible, increased heat doesn't reach the rockers. If you don't abuse your engine, (i.e. race use, drifting, bouncing off the rev limiter, revving past your power peak) I don't see them being an issue any more than stock. When I had ForcedFirebird rebuild my M20 head, he used resurfaced OEM rockers, I leaned on his spec E30/Chump car race experience to tell me that I was better off using inspected and surfaced OE rockers than buying IE HD. FWIW I have a 272° cam and my limiter is set to 6700rpm. I don't abuse my engine, I probably only hit the rev limiter a few times per month, I usually shift right at 6,500-6,600rpm if I rev it out.

i agree. i'm n/a and on a regrind cam, the hd rocker was overkill. i kept the others if i ever need as they were in fantastic shape.