Interesting youtube video's...

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immortality
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Re: Interesting youtube video's...

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The1
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Re: Interesting youtube video's...

Post by The1 »

pretty much as expected, only so much air the small cam will let through and also before velocity drops.
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Re: Interesting youtube video's...

Post by vlad01 »

Pretty much as expected as well, I thought maybe the biggest head would show slight improvement but it was too large in this case. But exactly as I expected, the whole curve moves up or down but only as minimal as the cam's baseline figures, where a matched head/cam will compliment and make more than the sum of the individual components.

In my experience having done 100's of engine simulations I found heads never really changed the curve shape, only moved it up or down, pivoting somewhat on the idle end of the curve.

What changes the curve fundamental shape is the cam, basic stroke/bore/cylinder config and to a large degree the intake design.

Exhaust has somewhat of a similar effect to the heads, mainly moves the curve up or down with change bias toward the higher rpm end. Low end usually does't change much. Bigger is better for the most part. Important area is the primary length and min required diameter is met.


What I do is figure out the basic capacity config, put the biggest logical/practical choice of heads, then design the cam to compliment the rest to their best potential.
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immortality
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Re: Interesting youtube video's...

Post by immortality »

It was a bit of a bandaid test using what we would consider a large cube engine with a tiny cam, test would have been more conclusive with a small cube engine (302/351) with an appropriately sized cam. In reality not very many people are going to built a 410 cube engine and put such a small cam in it with small heads etc

Those results are also only at 100% throttle, part throttle drive-ability would differ hugely between the small and large heads, fairly much the same reason the LS motors really lack much punch until they get up into the revs a bit.
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Re: Interesting youtube video's...

Post by Holden202T »

what it shows is that picking the right can can bandaid too big of a head hehe :)

i agree though, part throttle, coming out of a corner etc sort of stuff will show more differences in the two .... or even something as basic as fuel atomisation or economy i dare say would be very different at cruise!
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Re: Interesting youtube video's...

Post by vlad01 »

I don't think it would differ much at all. In my experience on the dyno and VE tables. WOT curve is actually a representation of the rest of the 3D area the engine operates in.

The whole basic WOT curve is extrapolated from WOT down to very low loads, only difference is the level of the curve drops with less load but same basic shape remains.

There might be differences in the amount it changes but it will only be a few % at most.

My opinion is get the best heads you can afford, even if its over kill, cam makes most of the difference of the two but only if the heads have well... head room.

Easier to change a cam than the heads and as proven, its not bad going too big. More horsepower is always the answer right?
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Re: Interesting youtube video's...

Post by Holden202T »

we've all seen how slow air speed effects economy and drivability, its not just the cam being the right size that will fix this ....

like they said in the video, would have been better to put the heads on a smaller block, would be a lot different then!

same thing goes for Holden 5ltr v's LS motors, the 5ltr is way better down low than an LS (to like 3000rpm), but it lacks at the top where the LS doesn't, as the LS has the heads and inlet better to handle it than the 5ltr.
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Re: Interesting youtube video's...

Post by firebug »

Lol! Who here lives in West Anal Sex? :lol:

[youtube]https://www.youtube.com/watch?v=U9tvln5JUW4[/youtube]
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Re: Interesting youtube video's...

Post by immortality »

For the space geeks out there,
[youtube]https://www.youtube.com/watch?v=KAyHeh7lk1Y[/youtube]
She's very easy on the eyes too :D
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Re: Interesting youtube video's...

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let me guess, vintage space?
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