Pre Cat Cooling & Oil Pressure

[Gnasher]

I'm getting round to sorting the bits & pieces on the Griff ready for Spring.

Last year I had a fan fail on the way to Classic Le Mans, so I've got 2 new ones to go on, & I'll get the rad checked whilst I'm at it. As with a lot of Griffs my spoiler has long since been swiped against a speed hump or such, should I make or buy a new one & fit it? I have the David Beer's 2 speed fan set up & whilst it has never been a problem so long as both fans are working, it can run a bit hot.

The other thing is the oil pressure. It does fall of as the engine gets hot. The engine is always run on Mobil 1, it has done less than 40K & was rebuilt by TVR Power at 28K when a valve stuck. It sounds & runs fine, but on a busy road when I'm in traffic it shows about 15lbs at 2K revs. Is it worth trying a stronger pressure relief spring in the pump? Or is it the gauge / sender?

Any advice or experiences appreciated.

SteveD

[Johno]

Spolier - yes, do a search as there's all sorts of different variations people have come up with, the clear message however is that it reduces running temps which if this years 24HR is like last years classic for weather you'll be grateful for.

Oil pressure - I would ditch the Mobil 1 (presume you use 15-50 variant already) and use an alternative from the list below ..

Silkolene Pro R or Pro S
Motul 300V
Millers 20/60 I think . . .

There's a lot of differing opinion on oils and everyone has their own favourite, I use Silkolene in mine and I'm happy with it, but it's a Serp. My mate uses Motul 300V in his pre serp 4.3 Wedge and loves that, the message here will generally be to not use the Mobil 1 10/40, some will use the 15/50, but most will say to use another brand to improve the pressure.

Pressure will always drop when hot and lower revs and the pre-serp generally seem to me to have lower pressure than the serps anyway, I certainly wouldn't be over concerned.

If the gauge if failing it will hit zero (max deflection) and bounce about etc before giving up the ghost, but yours sounds like it isn't?

There are alternative relief valve springs around and the best I know of is from Real Steel ..

Edited by Johno on Wednesday 2nd March 14:10

[spend]

'In traffic' your oil pressure will probably be @30psi! 'In Traffic AFTER a hot run' it will drop to the level you see... that is the beauty of the air/oil coolers they cool the oil before the temps rise unduly, just relying on the water cooling means there is no capacity to cool the oil when you plonk a really hot engine to traffic. Modwise or other fan control can do nothing to overcome this, if owners don't see that phenomena they just aren't trying hard enough IMHO

[FlipFlopGriff]

I've used Silkolene Pro R (Now called Fuchs Titan Race Pro R) which is the 15/50 on the 4.3 for a few years and its' excellent. Pressure shows 30 on tickover rising to 45 at higher revs. Always buy from these guys who support the Growl, and you get a discount for joining as a memeber. In fact always doing deals so keep an eye out.

http://www.opieoils.co.uk/p-705-silkolene-pro-r-15...

FFG

[Adrian@]

Steve...One of my shortened spoilers in the kitchen if want one when your passing, try it FOC if you want to see if that make any difference, (and a factory item too comes to think of it). Adrian@

[Gnasher]

Hi Adrian,

Thanks, I'm at the NEC 1 day next week, so I'll take you up on that.

[Gnasher]

Thanks to everyone for their comments.

I know that the V8s especially the early ones don't have massive oil pressure, but on both trips into Europe last year I had a fair bit of time sat looking at the oil gauge wishing it would go up a bit.

Mind you, it was hot, especially at Classic Le Mans, in a tent!

I'm not sure who fared worse in the heat, me or the car.

SteveD

[Adrian@]

Steve, just give me a call the day before.
Adrian@

[Adrian@]

Steve, before you come remind me to look for my adjustable tadpole oil pressure parts for your V8 pump (I have a box of them somewhere...and they are not on the kitchen table!).
Adrian@

[v8 racing]

The golden rule of thumb is 10psi per thousand of revs, pop the oil pressure relief out and either stretch the spring, put the stronger mgb spring in, or a ball bearing to sit underneath the spring.

[TVR Beaver]

v8 racing said:

The golden rule of thumb is 10psi per thousand of revs, pop the oil pressure relief out and either stretch the spring, put the stronger mgb spring in, or a ball bearing to sit underneath the spring.

Stretch the spring!!...
Once got a right telling off from a mechanic for just that on my old Triumph Pre-unit…. He said you’ve no idea what the oil pressure is after doing it… and spring rates are calculated exactly to give the correct blow off pressure… (stoped it knocking anyway)

Yes.. I’m with you.. Give it a stretch until you get the right pressure…

Mind you… how do you reduce it if you go too far… clip a coil off or two?

Is that what’s in mine then Rob

Edited by TVR Beaver on Friday 4th March 08:15

[spend]

This might be confusing the OP in relation to his original question AFIK. PRV is only going to release at ONE pressure point ie it limits pressure. AIUI Rob's point is that LR springs are set for an engine that revs only to @5000, TVR Preserp's with higher RPM have already had the adjustment made to the spring for 6500rpm. You should see 65psi readily if you rev up when coldish which will verify the spring is OK.

Unless the spring/valve has failed drastically it won't affect idle / low rpm pressure at all. Heat will have hardly any effect either.

[TVR Beaver]

do these things work as a on / off switch... or are they more progressive?.. I thought they would allow more to bypass as the RPM went up... But agree, they stretching of the spring only determines it's start point.. But not sure where that is for a normal spring in terms of RPM....

[spend]

Its a RELIEF valve, at opening point it simply lets off pressure. Oil is returned straight back to inlet side of pump, and valve closes when pressure drops hence you should see limit by revving when oil is cold. At that point it won't drop to 0 so valve just flutters open & closed to limit the pressure at set value IYSWIM.

[TVR Beaver]

So what pressure does it open at.. and does the pressure not go up after it's opened at all?...
Is it not proportional to flow and the amount it’s opened?... Therefore not on / off.. or open / shut… More a variable depending on the rate the oil is passing through?..
You don’t get a sudden levelling out of pressure as it opens?? Obviously oil temp and viscosity comes into play here also..

Edited by TVR Beaver on Friday 4th March 14:37