Wet race tyres

[R59]

Originally Posted by Denis Bassom

If only.

And the car is 75-100Kg overweight for the class.

And for my next excuse....

Throw the driver out then.

Or buy a Nova.

I just happen to know where there is one......

[graham bahr]

[QUOTE=Denis Bassom]

I NEED dry sump on sticky tyres in the dry!!!

QUOTE]

you do? almost all of the TRC brigade run slicks and almost non of them are dry sumped!

[graham bahr]

Originally Posted by Denis Bassom

Anyway, back to the point.

I have analysed every single race result this year be mixed FWD and RWD category series that can run list 1b or slicks/wets and had a wet practice then dry race (or vica versa).

The results SEEM to be that RWD cars are measurably slower in the wet than FWD IF they are restricted to list 1a tyres. On list 1b or slicks/wets there is no appreciable difference.

Can anybody confirm/deny this? Or even explain it!!!

And yes, I am bored sitting at work waiting for something to happen.

i can only speak from my own experience with my RWD cars, but i noticed in the wet the FWD cars might wander around the circuit as they struggled for grip but they could basically keep there foot in, whilst i was having to get seriously out of the throttle as my car didn't wander it wanted to spin, i guess the less grippy the tyres the worse this would be

[COLIN STUBBS]

dennis if your powers coming in and out with a wallop you always going to struggle in the wet. i had a group 1 cam in a capri once that came on song at about 3k and it was awful in the wet. went back to one with a nice wide power band and it was great.
we ran in ctcrc on tyres like al has and when they get devoid of most of their tread [not bald you know!!] they grip like hell,and soon show up any oil surge problems. most ctcrc men are wet sump experts!!! best i had was an old neil brown sump [bear in mind they ran on slicks with wet sumps in 70s/80s touring cars]which had wide sides,3 trapdoors inside and a windage tray. i used to get the light on after hard braking and going into right handers like gerards.that cured it.

[Al Weyman]

I have always used Moroso Road Race sumps and they deliver, big wing, 3 swinging gates 11/2 to 2 inches deeper the business also use a windage tray and a deep pickup on the pump, makes installation a bit tight that is the only problem and I had to trim an inch off one wing to clear my 17/8 headers.

A mate of mine who raced a Camaro who was a little shall we say, tight, would not pay out for one of these set ups and just welded a lip aroung the sump to stop the oil climbing up the side, he then had to fit an Accusump at great expense as he was getting bad surge under braking.

I see Toyo do a semi road race tyre but you are not allowed to use them.

[greenamex2]

I have the big wings, 3 swinging gates, an extra 1 1/4 inches of depth, a windage tray, a properly placed pickup AND an accusump.

Bye bye number four big end on group N slicks!

[graham bahr]

Originally Posted by Denis Bassom

I have the big wings, 3 swinging gates, an extra 1 1/4 inches of depth, a windage tray, a properly placed pickup AND an accusump.

Bye bye number four big end on group N slicks!

that dont sound right! thats way more gubbins in the sump than most have,
does your sump have a hoizonal baffle just above the normal oil level to stop the oil sloshing vertically up the sides of the block? vertical baffles do more to keep the oil in check than horizonal ones.

lately there has been a lot of talk about using blocks of fuel tank foam in sumps to help control oil movement.

do you maybe have OTT oil pressure or big capacity pump with is pulling so much oil out the sump its ending up in the topend somewhere and taking too long to drain down giving you effectivly a low oil level when running?

are you seeing low oil pressure on your gauge/ warning lamps?

[greenamex2]

Yep. It also has the vertical trap doors!

Oil pressure is around 60psi, with the smallest capacity external pump that PACE do.

The data logging showed low oil pressure, shortly before the rest of the engine.

Most of the oil ends up in the head anyway making all the sump baffling pointless anyways. This is due to a combination of oil surge and Toyota being useless at designing heads that allow oil to get back to the sump.

And yes I do have an oil flow restrictor on the cylinder head supply.

Three engine builders (one OK, one highly respected and one ex-F1, ex-Touring car etc etc) and Pace have all had their hands on this engine at some time to try and fix the problem. The only answer they ever come up with is to bypass the problem and dry sump it.

If I owned a Ford I would have a much better house/holidays etc. But that wouldn't be fun, would it?

[COLIN STUBBS]

ok denis i give in. ooh iv thought of something else. is your windage tray made so as it dumps all the oil drained and dripped down from inside the engine straight onto the pickup.whats the clearance between the bottom of the sump and the pickup.wheres the rv dumping its oil-it needs to go near the pickup. what oil are you using and if its not 20/50 why not? why is that big pink bird standing on one leg?

[greenamex2]

It drains into the sump pickup area. Don't know, will have a look over the winter. What is the 'rv'?

Oh, just work out what an 'rv' is. My oil pump, believe it or not, doesn't have a pressure relief valve as most people would understand it. Being externally mounted the is nowhere to dump the excess oil so it does some 'trickery' that tries to achieve the same end. Personally I don't think it's doing a very good job but nobody seems to have my problem!!!

I'm using 10/40. A lot of articles I read said lower viscosity equal lower temperatures because you are circulating the oil faster. I am now beginning to think that is cobblers, it was off American sites after all. What I need is something like a 5/50 or 5/60 but we found before that the car was killing multigrade oils very quickly. Pressure after 3 or so races was noticably less but went back up after an oil change.

Who said it HAD more than one leg?

[Al Weyman]

Dennis Graham may be rightwith the Horizontal baffle he was talking about, not vertical, it stops the oil climbing out the sump under heavy cornering. In my previous post where I mention a mate of mine running his chevy on a standard sump this is exactly what he did and apart from some surge under braking, under power and cornering ot was fine. He weld a 1inch strip of steel about 1 inch below the mounting flange of the sump and went all the way around the deepest part of the sump being a rear loader. I may even have one of the modified sumps somewhere I could take a picture of. Is the sump in your car front or rear loading?

[greenamex2]

Front loading. Thanks for the offer, all help greatly appreciated.

Just got my completely redesigned oil pump back from Pace. They have done their usual excellent job. At least I shouldn't be pumping oil all over the circuit now!

[Al Weyman]

Front loading, that makes it a little trickier I bet you get no surge under heavy braking trouble is you want no surge under hard accelleration, I will have a look later and see if I can find the modified sump pan.

[COLIN STUBBS]

spent a couple of hours last night having a few beers with a guy that helped me thru the oil surge problems we had a few years back and he came out with some things id forgotten. al is right about baffles. and unless you have some horizontal baffles,vertical ones are useless. the oil will stand up the side in a corner.2 things he did recall though was temperature and oil type. we fitted a 23 row cooler and kept on using it,just blanking a bit off in cold weather.use the biggest oil lines possible to help keep the flow up.number 2 was oil.i used to get all types of expensive stuff free and never realised that mobil1 and the like was no good for our engine due to the internal clearances,etc being too generous!we got some valvoline racing 20/50 and this improved our situation instantly. from that we went a bit chavvy and found some Qualube special f racing oil from local small oil company,Witham oils.£25 for 25L. Magic stuff and never ever had another problem. By this time the beer intake had taken hold and the conversation became sillier.,but hope it helps.

[greenamex2]

Witham oils bookmarked pending a troll round the Autosport show. Thanks for that.

Now we have made some progress on oil, I suppose I am going to give up and get some wet weather driving lessons over the winter.

Anybody interested in a day at Silverstone Rally school?

[graham bahr]

[QUOTE=COLIN STUBBS] we fitted a 23 row cooler and kept on using it,just blanking a bit off in cold weather.use the biggest oil lines possible to help keep the flow up.QUOTE]

i found the same colin

when i re-engineered my engine as a turbo, i added oil cooling sprays to the underside of the pistons as well as the oil feed to the turbo, knowing my engine was already a bit marginal on high rpm oil supply without all the extra oil demands, as well as radiusing all the oil ways in the block ( the oil from the pump makes 4 90 degree turns before it gets to the main gallery, which in any case is a bit too small for very high rpm) i radiused and flowed the oil cooler take off plate and went up from 5/8 to 3/4 bore oil cooler and hoses hoping to reduce any flow restriction ( you will always get some when pumping through pipework)

it certainly worked a treat, i now have 50% more oil pressure at idle on a stonking hot engine at the END of a race dispitee the extra load on the oil supply, and the fact i now use thinner oil to suit the turbo

the above wont help dennis but its interesting non the less.

maybe dennis should consider an external oil drain from the head like they used to fit to Hillman IMP sports (normal imp didn't have the this)

[greenamex2]

Possibly not completely irrelevant to me. I think I will certainly have a look over the oil system over the winter. Things like sharp edges and insufficient pipe sizes could be a factor in equation.

We put in an external drain back but it isn't exactly optimally placed, being on the same side of the engine as the design defect already built into it, and it's too high up. I was planning to move it over the winter when I have time to take head off.

Out of interest, where do you drain the oil back too, below the sump oil level, above it but below the baffle plate or above the baffle plate?

PS. I had a Hillman Imp once, fantastic car.

[graham bahr]

Originally Posted by graham bahr

vertical baffles do more to keep the oil in check than horizonal ones.

?

typo error there i've written that the wrong way round, should read, horizonal baffles do more to keep oil in check than vertical

[graham bahr]

Originally Posted by Denis Bassom

Out of interest, where do you drain the oil back too, below the sump oil level, above it but below the baffle plate or above the baffle plate?

PS. I had a Hillman Imp once, fantastic car.

from a get the oil where it really beings point of view, below, however above may drain the head better, unless its a substancial sized drain.

i used to quite regulary get my IMP on two wheels round corners, didn't seem to cause oil surge though.......

[COLIN STUBBS]

id drain the lot back inside the block if poss.onto a windage tray shaped slightly convex to let all the oil run onto the pickup. ext pipes are ok but think what may happen if its on the n/s and your barrelling round gerards or coram. no drain. best is to bore out and grind all the internal oil drains and make sure it can get out ok.iexperience weve had with accusumps and oil stats havnt been good. they all seem to destabilise things like chucking oil in at different temperatures,etc. everyone has different thoughts on these things but it seems to work best if you have good pressure,not too much flow,but as less a resistance as poss with oil pipes/unions,etc,and get the lot onto that pickup!!

[graham bahr]

the thing about accusumps that concerns me is that they might prevent a very momentry loss of oil pressure, then cause a period lowish pressure while they charge up again, or do they have some sort of pressure valve so that they are only charged up when the engine has high oil pressure?

but whatever, they are only treating the symptoms not the problem

[graham bahr]

Originally Posted by COLIN STUBBS

everyone has different thoughts on these things but it seems to work best if you have good pressure,not too much flow,but as less a resistance as poss with oil pipes/unions,etc,and get the lot onto that pickup!!

i certainly think you can have too much oil flow from the pump, and cause oil surge just because the sumps almost empty, i remember one particular essex V6 which was so good at pumping oil the entire contents of the sump would end up in the rocker covers as it was being pumped out the sump faster than it could drain down again, although in this cause it was partly caused by a late type cam follower (as fitted to 99.9999% of engines) being fitted to a very very early zodiac engine which had a very slightly different follower design

[graham bahr]

this tyre thred is certainly wandering,

but i guess thats the sign of a good forum

[Al Weyman]

Personally Grahame I think you have made another very valid point, I did wonder why Dennis needs the external Pace pump as the original must have performed adequately for many thousands of miles in a road engine. It is the same with the Chev small block, some have fiited large capacity pumps even Big Block pumps but a lot of builders usually reckon the the standard sized pump is more than man enough and in fact the bigger pumps can actually rob BHP. Incidently going from one end of the engine scale to the other I was interested to read you messed with Imps as I used to work for Nathan Racing years ago and built a few race units.

[graham bahr]

lots of engine builders go over the top with oil pumps, my beemers have never used anything other than a std oil pump,

my mate who ran an engine tuning shop right through the 60's-90's built 1,000's of pintos and x/flow for race and rally and never used anything other than a std pump, and never once suffered a bearing failure as a result

the plain truth is that unless something else is wrong or the origonal engine is marginal a modified engine doesn't actually need any more oil pressure than a std engine, higher power outputs put very very little extra load on the bearings, the pressure is only the supply pressure to the bearings, the actuall pressure within the bearings themselves can be many thousand psi, adding a few extra pounds to the supply pressure does diddly squat, infact some times it errodes the bearings!!

i also suspect on some engines it does nothing more than throth up the oil as it gets dumped by the pressure relief valve and swirted back through a tube into the sump or crankcase.

opposite end of the scale was the V8 rover engine, if one of them had 35psi oil pressure that was a lot, it never caused them a problem

going back to imps we used std pumps on imps, which as you will know fully modified rev to 10,000rpm using r20/r23/ hartwell 410 cams, which is double what the std engine was designed to, what they did need though was an uprated oil pump drive gear as the high revs wore std ones out.