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Mechanical RPM limit ? (and yes i searched through all the BS)

Oh, the k cam is pretty much shut down after 6500-6800

Yes. I ran for a bit with a k-cam in a stock head, Nathan intake, tube header, holset blah blah (a better flowing setup than being discussed here is my point). I set the rev limiter at 6900 and it was gassed out by then.

BUT I'm just the dick with first hand experience :p
 
...I wish someone with aluminum retainers would Chime in...

I did chime in, you either didn't read it or are ignoring what I (and others) have said.

I used to work in an engine machine shop (my dad still runs it), he primarily builds race motors and vintage motorcycle engines. I have removed cracked aluminum retainers on at least 2 occasions, and the run time on these motors were in the 20 hour range.

Once again, do not use aluminum retainers unless you're drag racing and replacing them after 2-3 hours of run time. They WILL fail.

K-cam revs out just fine when it's retarded a few degrees and the ignition timing is bumped up 5 deg or so.
 
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I used to run my hy35cw powered car up to a 7100 limiter on a stock unported head without any valve train issues or block issues.

This was at 26psi.
 
The mechanical limit is how fast your valves can open and close. YOu already got double valve springs so you got that covered. The aluminum keeps are race only and yes you change them all the time, every race. I used to have my old hot rod and no rev limit lh2.4 and rsi stage 3 turbo cam and double valve springs and would rev it to 7500rpm and more even. Valve float is when your valves can't open and close fast enough and that is what keeps the motor from revving faster. There is your final answer only took 24 posts to get there..

Zero to sixy watch the tach, goes below and around and past the 7k on the dial..

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<iframe width="560" height="315" src="https://www.youtube.com/embed/ua683dLR0Ao" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
 
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I somewhat regularly zing my B20 (olde pushrod OHC motor) to 7500 rpm, with the carbs/cam/head/exhaust it's still productive there.

I've also replaced a cracked piston once in the past, and I currently have a cylinder with low compression that's leaking into the crankcase, so probably same thing again.

It's pretty fun to just keep your foot in it and let 'er rip.
 
Nothing wrong with reving to 7-7500RPM
The big issue nobody is mentioning here is injector duty cycle. Having a single injector that flows little enough for tick over and enough to rev to 8000RPM is 3rd gear is a issue

The alloy retainers you do need to watch and I would suggest replacing at some point with steel ones as you are not planning on changing them often.
 
you do know that hondas and such run normal fuel injectors, right? there's nothing special there that would be RPM related.
 
I was wintering if anything had changed l lol there still junk..I drag race and nobody I know uses them,but metallurgy and methods change over the years I was wondering why they still sell them? Maybe for a dyno queen engine and they got changed every couple pulls
 
Ok i got my answers thank you.

I will definitely change the retainers to the stock ones.
About the injectors, i got ID1000's and they are very nice to tune from idle to redline.

I will keep my limiter at 6500 untill i dyno it and change the retainers.

Retarding the cam timing, i still got the stock pulley, and don't plan to change it for now.

Thank you everyone
 
I have nothing but a faint hunch to go on, but I suspect sequential injection mostly just sounds better from a theoretical standpoint. And probably, on a modern super clean engine (err, not so modern it has direct injection, though) it probably makes a difference at very low/idle rpm in emissions, there is enough time for gasoline to either evaporate or condense if it sits for most of the cycle vs. getting done with the squirt right as the intake opens. But at high RPM's, the duty cycle goes up, to where they're spraying fuel a lot of the time anyhow, and there's very little time for either further evaporation or condensation to occur, so it doesn't really matter even a little.

I know I wired up sequential injection on my 16V, and with a simple click or two in TunerStudio I could change it form sequential to paired batches to single batch. And I could not detect any differences in the way it ran or idled. And when running sequential injection, I played around with the injection timing, pretty much all the way around the 720 possible degrees of timing vs. TDC, and none of that seemed to make any detectable difference either. Certainly not something you'd notice driving or listening, but not even something that the WB picked up on either.
 
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Full group v sequential injection

Yes you can make it sequential injection but most are not doing that

batch vs sequential has nothing to do with it. It's simple really... Either you can provide the volume of fuel required at a given rpm or you can't. That's it. As the engine speed increases, unless the VE is also increasing (pro-tip: on an 8v it's not), you're not cramming in as much air in the same period, and the required fuel drops off. This is where the hondas and the volvos diverge...

but an injector is an injector. Either they're large enough for the task or they're not. I've gotten 1600cc injectors to idle fine, others have gotten 2200cc injectors to idle fine, this.. this is not even worth talking about any further.
 
Going back to LH2.4 and most other batch fire OEM injection systems they fire the injector twice per duty cycle. So lets say your injector minimum opening time time is 2ms the injector is going to be open at least 4ms so double the amount of time you would find in sequential injection.

It is a problem I see all the time in LPG conversions but many systems have adapted and allow you to filter out the second pulse so the LPG injector only opens once (typical minimum LPG injector opening time is 3ms)

Most stand alone injection systems look to only fire once per pulse but even so as the RPM rises the window before the injector becomes fully open gets smaller and smaller and we still need good control at idle under no load
 
Just FYI, i got an answer from KG Trimning about the alloy spring retainers.
Apart from the fact they told me they have sold hundreds of them wihtout any issue, the alloy used is EN AW 7075.
 
Going back to LH2.4 and most other batch fire OEM injection systems they fire the injector twice per duty cycle. So lets say your injector minimum opening time time is 2ms the injector is going to be open at least 4ms so double the amount of time you would find in sequential injection.

It is a problem I see all the time in LPG conversions but many systems have adapted and allow you to filter out the second pulse so the LPG injector only opens once (typical minimum LPG injector opening time is 3ms)

Most stand alone injection systems look to only fire once per pulse but even so as the RPM rises the window before the injector becomes fully open gets smaller and smaller and we still need good control at idle under no load

if your injector minimum opening time is 2ms, you have garbage injectors and should get out of the 1970's. even the cheap non-Chinese injectors floating around now have nominal opening times of less than 1ms. I've gotten 1000cc injectors wired to batch to idle fine, and we're talking deka 1000cc injectors, the old school slow ones with about a 1.2ms dead time.

And higher in the rpm band, again, you've missed the boat. Please stop. You either have enough injector or you don't.
 
First 13 seconds - wow, that's a lot of fuel:
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After that: :omg:
 
Just FYI, i got an answer from KG Trimning about the alloy spring retainers.
Apart from the fact they told me they have sold hundreds of them wihtout any issue, the alloy used is EN AW 7075.
This is what I was wondering this way I can stop spreading bull **** about a product I haven't used...things apparently have changed sorry I blew up
 
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