i guess if the car isn't moving or is moving slowly and the engine is
running at 240, the engine bay is so hot that the intake charge is
warmer and hence less dense than if the engine is at 180. therefore
less hp.
not too convinced myself as the difference is not huge especially when
moving. but its an argument.
On Fri, Aug 29, 2008 at 5:14 PM, Dave Munroe <dave@munroe.ca> wrote:
> Optimal oil pressure....
>
> A question I was afraid to ask. I have seen on this list and others, as well
>in propaganda from owners trying to sell their cars,
> claims of oil pressures in their SBF's of 60 psi at "speed".
>
> My oil pressure at start-up cold is 45 psi on the gauge, dropping to 30 as
>the engine heats up and reaches 225 230F at 3,000 rpm and up.
> It would drop to 20 at idle "hot".
>
> Now that I have it running at 180-190F, cold pressure is still 45psi. but it
>never drops below 40psi, now, at operating temp.
>
> Hot-rodder's I have spoken with say 10 psi per 1,000 rpm is lots for a
>"built" engine.
>
> What's considered normal or adequate by the Tiger community??
>
> Dave
> ----- Original Message -----
> From: MWood24020@aol.com
> To: dave@munroe.ca
> Cc: tigers@autox.team.net
> Sent: Friday, August 29, 2008 12:28 PM
> Subject: Re: [Tigers] How hot is hot ?
>
>
> In a message dated 8/29/2008 8:03:06 A.M. Pacific Daylight Time,
>dave@munroe.ca writes:
> One of the reasons why I worry about my engine overheating ( 225- 230F) is
> the noticeable drop in oil pressure.
>
> When you did your oil temp testing on horsepower gain, did your FF oil
> pressure drop with a rise in oil temp?
>
>
>
> Which, I guess, brings us to another (but, linked) discussion: "optimal" oil
>pressure ;-)
>
> Yes, we did see drop in oil pressure. Idle pressure, post race, was in the
>10 psi range with about 25-30 psi at anything over 3000 rpm...which was plenty
>in that application, evidently, as we went two years without an engine
>failure. When the motor was taken down, bearing wear was normal. Keep in mind,
>this is just a VW motor, air cooled, low(er) rpm etc.
>
> The other thing that I didn't consider, when I posted earlier, was excessive
>piston/piston crown heat, which can lead to power loss...in some cases, TOTAL
>power loss...I was thinking more of elevated engine heat in the intended
>operating range.
>
>
>
>
>
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