Bill,
That being said, the dyno tests involved a fully developed race engine
run with stock rockers and again with roller rockers. The difference
was 2 h.p. - maybe a 1-2% difference overall. Hardly close to a 10%
gain as some promise as a bolt on improvement (I would assume that this
figure is for a stock situation). It is clear that the pin bearing and
roller will reduce friction but the increased leverage will also add
more work at the tappet end. As in everything, there is a limit to
improvement. As machines become more refined, the next increment of
improvement usually becomes smaller and more difficult to obtain. My
point in asking the original question was whether or not roller rockers
really added more horsepower due to a longer valve duration assuming
that all the other bases were covered - friction aside. I would assume
that there is a limit to just how much air/fuel mixture you can suck
through a Triumph head as fully developed as it may be. The dyno test
would seem to suggest that.
Allen
On Dec 26, 2007, at 4:56 PM, Bill Babcock wrote:
> Not that I'm trying to tell you how to suck eggs, but the primary
> reasons for
> using roller rockers are to decrease side thrust on the valve stems,
> reduce
> friction in the valve train (pin bearing in the rocker and a roller)
> and
> reduce reciprocating weight. The only way that translates into higher
> horsepower is to take advantage of the opportunities these factors
> enable. A
> lot of speed equipment is sold to people with no plan to take
> advantage of the
> factors the equipment was invented to improve. If your cam won't
> benefit from
> a higher rocker ratio then you won't gain anything from it. If you're
> not
> prepared to experiment with shorter intake valve guides to improve
> flow then
> the reduced side thrust won't give more horsepower, just better guide
> wear--which none of us care about.
>
> You can get a lot of horsepower from roller rockers, but not by
> bolting them
> on.
>
>
> -----Original Message-----
> From: fot-bounces+billb=bnj.com@autox.team.net on behalf of Allen
> Washatko
> Sent: Wed 12/26/2007 2:20 PM
> To: Friends of Triumph
> Subject: [Fot] Roller Rockers
>
> FoT,
>
> I need some input regarding the use of roller rockers on a race
> prepared TR6. If you are running a cam with .500 lift and 300 degrees
> duration, does the use of a higher ration roller rocker (1.65) really
> add that much more power? This is assuming that the head is well ported
> and you are running the largest intake/exhaust valves that fit in the
> head. I was just made aware of some engine testing recently that
> indicated that there was only a 2 h.p. gain by using roller rockers
> with the above modifications. It also indicated that the increased
> ratio caused more wear on the cam, tappets, etc. The logic as presented
> seems to be that you can only draw so much flow through the head
> before you get diminishing returns. Any thoughts on this?
>
> Allen
>
>
> Allen & Jody Washatko
> 1971 TR6 - Number 6
> Fot mailing list
> Fot@autox.team.net
> http://autox.team.net/mailman/listinfo/fot
> _______________________________________________
> http://www.team.net/donate.html
>
> Fot mailing list
> Fot@autox.team.net
> http://autox.team.net/mailman/listinfo/fot
>
>
Jody & Allen Washatko
N65 W5567 Columbia Road
Cedarburg, WI. 53012
USA
tel. (262) 375-6888
_______________________________________________
http://www.team.net/donate.html
Fot mailing list
Fot@autox.team.net
http://autox.team.net/mailman/listinfo/fot
|