[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: SVO - svo Digest - V01 #50



On Tue, 9 Dec 1997, Mp23cc wrote:

> You are on the right track. This is why we use alot of valve lift and not much
> duration. We can make great lowend torque do to the short duration. The high
> valve lift along with the boost gives you great top end power. Alot of
> duration will cost you lowend , but high valve lift will not cost you
> anything.

Actually, there are plenty of costs associated with running high-lift
camshafts...some are mechanical, some are financial...

Mechanical:  If you run more lift that you need for a given application,
you lose velocity, flow and the homogeneity of your air/fuel mixture as it
enters the chamber, not to mention the extra wear that a high-lift cam
puts on valveguides and other valvetrain components...I hear you've had a
bit of trouble with this recently...care to discuss it here?

Financial:  If you have to totally re-work your valvetrain to accomodate a
.500"+ lift cam, that's a considerable expense to most people -- cutting
the pockets and guides, getting different valves and springs, etc., having
to totally re-engineer the valvetrain geometry...that's a big deal.  I
think you said that you get $6XX for your kit -- that's a decent price
all-in-all, but that's only the tip of the iceberg...and what can
somebody reasonably expect to get for this investment?  

I'm not saying that a big cam won't help at all, but without any real
testing (like Dave's XR deal), I'm not gonna buns up for one...and I'm
not talking about "feels like" testing, either... 

That's why I'm not making any (outrageous) claims for ours...All I wanted
was to make a decent, stock-ish roller without the extra exhaust duration
and narrow lobe centers, like all the other "rumpety-rump" cams I've seen
out there.

BTW -- I'm basing my opinions not just on 2.3 stuff...know what one of the
coolest turbo grinds is for the 5.0?  The stocker.  Wanna get really
tricky?  E303...  Show me a single camshaft that makes significant gains
over a stock cam in a turbo motor...has anybody seen one?  Nick?  Anyone?
I'm waiting patiently...when I see it, I'll put it in my car and run it.

> With most motors you do have to give up something somewhere.

With ALL motors...

> With a turbo motor you need to have a good lowend working camshaft and
> let the boost give you the top end. 

Personally, I think it's a little silly to be sitting here constantly
talking about high-performance motors and "low-end" torque...come
on...we're all sitting here wit 3.126 stroke 4-bangers with fairly large
bores and too-big intake ports talking about "low-end torque"...if you
want low-end in a 4-banger, buy a 22R Toyota, or better yet, put a 22R
crank in a 2.3, it's nearly a bolt-in and yields a 28XXcc motor with gobs
of "low-end" torque.

> Camshaft like this will produce near stock idle or better, great lowend torque
> and still pull to redline. You can not match this performance with a short
> lift camshaft. Good luck

Like I said before, MAYBE it does help, but it would be the first time
I've ever seen a camshaft that makes more power *everywhere* on the
powerband...so where are the dyno sheets?  You show me some proof -- a
back-to-back test, and I'll use it...until then, it goes in the "Tooth
Fairy" file, with all the rest of the something for nothing stuff I've
seen.

My experience has been that you make your own luck, mostly with attention
to detail and hard work, but thanks nonetheless.

Joe Morgan