Oil Surge = Misfire?

[Julian West]

Interesting thread...!

I've also been suffering from oil starvation during track days & sprints. I'm using an Armandos GT40 sump. I've been wondering if the problem may not be the sump itself, but more a case of the oil not returning back into the sump...??

I figure a correctly baffled sump will only do its job if it's got enough oil in it at the crucial moment.

One theory I've heard is that under braking, when the oil is thrown to the front of the sump, the timing chain 'picks up' the oil & throws it to the top of the timing chain area. The oil cannot get back down into the sump quick enough & therefore the pump soon sucks the sump dry...???

Dry sump does seem to be the ultimate answer, but there are plenty of wet sump 302's racing all over the world. Perhaps these are the guys keeping the engine builders in work?

Regards,

Julian West

 

[Jac Mac]

Let me put it this way..I have the facilities and 'hopefully' know how to build the fanciest wet sump possible for a GT40 type car & track use, but I wouldnt waste my time. The argument that the originals used them no longer holds water or oil for the following reasons.
1. Todays road tires probably have more grip than ~60's race tires.
2. Most if not all of you guys have brake packages that are far superior to the originals.
3. Stroker cranks with the larger swing radius & therefore higher counterweight speed mandate a lower oil level in the pan & create more windage problems- the larger ~4" cranks in 351 blocks are even worse.

 

[Jim Cowden]

I would have to agree with you Jac.
These oil surge stories have been common for the 5 years or so that I have been a user of this site.
I went drysump because I could see the writing on the wall, eng rebuilds cost money.
In my last race car if I had one or 2 oil surges the eng came out for a look.

Julian does your missfire happen on full tanks.

Jim

 

[Jack Houpe]

Let me put it this way..I have the facilities and 'hopefully' know how to build the fanciest wet sump possible for a GT40 type car & track use, but I wouldnt waste my time. The argument that the originals used them no longer holds water or oil for the following reasons.
1. Todays road tires probably have more grip than ~60's race tires.
2. Most if not all of you guys have brake packages that are far superior to the originals.
3. Stroker cranks with the larger swing radius & therefore higher counterweight speed mandate a lower oil level in the pan & create more windage problems- the larger ~4" cranks in 351 blocks are even worse.

I always look forward to reading your posts, always educational for me.

 

[Julian West]

Thanks for the informative posts gents. I have no doubt that the ultimate technical solution to prevent oil surge is to dry sump the engine.

However there are race and sprint series in the UK in which the technical regs do not allow dry sump. I assume this is to keep costs down.

If it is the case that dry sump is not permitted, what are the engine builders recommendations?

Regards,

 

[Jac Mac]

Thanks for the informative posts gents. I have no doubt that the ultimate technical solution to prevent oil surge is to dry sump the engine.

However there are race and sprint series in the UK in which the technical regs do not allow dry sump. I assume this is to keep costs down.

If it is the case that dry sump is not permitted, what are the engine builders recommendations?

Regards,

Ive had this idea for some time, but never really had a car or client with the need to try/experiment on & put it into practice:

With a wet sump , once the pressure oil has passed thru the filter take it to a tall circular tank ( Say 5/6" dia & approx 12/15" tall ), feed it into the top of the tank in a centrifugal manner as you would a normal dry sump tank. Out of the bottom the oil would feed via a cooler if reqd to the engine. Out of the top via a ~30lb relief & 3/16" approx restrictor take a line & dump it back via spray bars to the valve springs.

My thinking with this is any air pumped into the 'Tank' during braking/cornering etc would bleed out via the relief & spray bars while the remaining lube ( about 3 or 4 liters ) would continue to feed the engine in a 'less' aerated form.

Sort of an auto accumulator with a self air bleed if you like...dont even know if it would work in practice, but might give it a try one day...on someone else's motor.

 

[Pete McCluskey.]

Jac Great idea, I think you should patent that.

 

[Jac Mac]

Jac Great idea, I think you should patent that.

Been down the patent route before Pete, never again. Still waiting on the rich's promised:thumbsdown:
My understanding is that once you put an idea or plan out in the public domain, such as I have in the post above, that no one can actually patent the setup, although they can claim IP for any further input they feel they have made on there own attempts.
However, if anyone wants me to investigate it further, you know where to send the $$ Wyatt..oop's...Ron Earp needs one to prevent that Lola becoming a Grenade @ the 12 hr 59 minute mark---perhaps I should do a deal on a lifetime membership to this site....naaah that would involve a trip to the states to fit the damn thing..

 

[Seymour Snerd]

My understanding is that once you put an idea or plan out in the public domain, such as I have in the post above, that no one can actually patent the setup, although they can claim IP for any further input they feel they have made on there own attempts.

You have a year after publishing in printed form or offering the device for sale. I don't know if "gt40s.com" qualifies as a "printed publication" but I doubt it.

So, get to work. You have 364 days. :thumbsup:

 

[Ron Earp]

Wyatt..oop's...Ron Earp needs one to prevent that Lola becoming a Grenade @ the 12 hr 59 minute mark---perhaps I should do a deal on a lifetime membership to this site....naaah that would involve a trip to the states to fit the damn thing..

Actually.....we're pulling the gearbox to flip the R&P and I am seriously considering fitting a dry sump since the car will be down awhile and the engine easily pulled.......

Come on over and visit! We won't even make you do any work. Don't joke too much on the 12:30 mark - a few years ago a Miata we were running broke the crank in the last stint, about 35 mins to go.....was a bummer.

 

[Russ Noble]

Actually.....we're pulling the gearbox to flip the R&P

WTF! Really? Tell us more.....

Sorry about the thread drift in the Engines Forum. Maybe you should post this to the Jokes thread in the Paddock?? I just can't wait to read the punch line!

Just figured out why. You guys are going to be pushing so hard that you will be spending more time going backwards than forwards so you've decided to have four reverse and one forward gears...... Brilliant strategy.

 

[Ron Earp]

Actually, sorry for mentioning anything about boxes here. Things need to remain on topic.

Oil control on wet motors?

I am no expert but my racing Z engine is prepped as follows:

*Head looked at for oil return problems. Holes radiused, enlarged, and some people paint the surface of the head saying that it helps oil drain back. Depending on your engine design you may have to restrict oil flow to the head.

*Windage control - can be built into the pan or you can use a crank scraper. I use both. Home

*Oil pan with kickouts and trap door system. On the Z I have used two pans, one works and one doesn't. The NISMO piece works great. It holds eight quarts, has kickouts, a diamond shaped trapdoor system, and some windage baffles sticking up from the pan toward the crank. My Arizona Z pan has the trap doors but nothing else, and, it does not work well. Oil pressure drops around the 1.15-1.2g mark during cornering. Bad. NIMSO bearings at 32 hours of use looked beautiful. Arizona Z pan bearings at 15 hours of use looked not so good and could use replacement. Couldn't fix the Arizona pan with oil level etc, always seemed to drop pressure.

*I used to use the Accusump band aid but when I was using the NIMSO pan it was not needed. Putting my Accusump back in the Z just for the hell of it as it doesn't hurt anything and I'm not weight challenged.

T70 has a Canton RR pan and that is it, no crank scraper etc. Thus far none of the data we've collected shows any sort of oil pressure drop in cornering on two different tracks, but, that doesn't mean it won't happen. I'd rather it not happen, hence the DS consideration.

 

[DaveM]

I would generally agree with JacMac having lost a 280Z engine at Daytona (what was I thinking with a wet sump and all that banking?). I now do occasional track days with my SPF40 (351W stroker). Have a Canton pan and 3 Qt. Accusump. With really hot oil (115C) pressure is 40psi, but drops to 20psi on left corners only. Rpm's on these corners is under 3000. Right corners no pressure drop. Is this worrisome?

 

[Jac Mac]

I would generally agree with JacMac having lost a 280Z engine at Daytona (what was I thinking with a wet sump and all that banking?). I now do occasional track days with my SPF40 (351W stroker). Have a Canton pan and 3 Qt. Accusump. With really hot oil (115C) pressure is 40psi, but drops to 20psi on left corners only. Rpm's on these corners is under 3000. Right corners no pressure drop. Is this worrisome?

When you turn left the oil stacks up on the RH side of the pan, with normal crank rotation this is also where most of the oil draining back gets tossed as well, plus if enough gets trapped in this area the crank will grab hold of it again & toss it up into cyls 1-4 & cam cavity, which of course means there is not a lot left in the pan to pickup. In your case a couple of near vertical scrapers in the center of the pan might help to keep it downstairs long enough to cover the turns in question, but as we have already discussed its a bit of a lottery..

 

[Glenn M]

Jac Mac that's interesting and the total opposite to that which I experienced!? My problems were long right hand corners with no problems on the left handers! (331 S.B.F.) No idea why. As I said though the problem went away when I changed from an original GT40 style sump to a Canton and a crank scraper.

Glenn

 

[Julian West]

Glenn,

Would you mind detailing which Canton you went for? Looking thru their website this looks ideal;

www.cantonracingproducts.com - 15-630 - 302 FRONT SUMP RR PAN

Did you use a windage tray aswell? & if so which one?

Regards,

 

[Jac Mac]

Jac Mac that's interesting and the total opposite to that which I experienced!? My problems were long right hand corners with no problems on the left handers! (331 S.B.F.) No idea why. As I said though the problem went away when I changed from an original GT40 style sump to a Canton and a crank scraper.

Glenn

Your 331 is not a major offender in regard to windage, but I wonder if your particular concern might be due to the baffle clearance around rhe oil pump as per this dwg.

 

[Ron Earp]

Glenn,

Would you mind detailing which Canton you went for? Looking thru their website this looks ideal;

www.cantonracingproducts.com - 15-630 - 302 FRONT SUMP RR PAN

Did you use a windage tray aswell? & if so which one?

Regards,

That is the pan that we're using on the T70. And to correct what I wrote earlier, we've got a crank scarper from the Johnson folks on the engine too. I forgot that we'd put one on last fall and it needed work to function with the Canton pan.

 

[Julian]

Thanks for all the info lads, particularly all the feedback about the Canton Pan, which is what I've gone for. I went throught the excersise of pricing up a dry sump conversion and it comes out to US$2000 at least! Which is too much for me to afford right now.
I've ordered a Canton 15-630S pan and pickup today, so hopefully should have them in a few weeks. The 15-630S pan kickouts are only 12 inches wide, so will fit between my engine mount posts in the DRB chassis, where as the wider 15-630 pan will give me trouble.

Will let you know what the result was when I get it all fitted up and head for the track.

 

[Ron Earp]

The conversion is not chump change. That is for sure. And likely there are many other things that may need to be reconfiguring which will cost additional money.

I'm still considering it though because to do an endurance race we're already in the hole $4-$6k without turning a wheel. It is expensive to get a car on track and when that is considered $3k doesn't seem all that bad. And then if Jac Mac comes over and does all the work and reconfiguring for free, plus he crews for us, again for free, well, it seems like a good deal!!