Good morning everyone. I am in the process of upgrading my oil system. This is on my dedicated track 914. The upgrades include remote oil cooler, accusump, and CB Maxi oil pump.
In my research for installing the accusump it seems like there are two places that are recommended, in the cooler return line with a check valve and direct to the block. I did not want to use the sandwich plate adapter so I opted for the block option. Simpler with less seals to fail.
As I looked into the workings of the type IV oil system I found a potential problem with both these locations; the oil relief valve on the front of the engine. VW used this valve to bypass the cooler when the oil is thick. But this also means the cooler is bypassed when the oil pressure is high. Does the use of an oil accumulator negate the oil cooler system by maintaining oil pressure?
While on the straights the pump could potentially make 50-60 psi of oil pressure. (the 30mm pump that was in the engine produces those pressures much of a 20 min session) At those oil pressures the cooler will be bypassed based on what I know of the relief valve (bypassing cooler at 60psi, partially open at 35 psi, and sealed at 12psi). The accusump will also build up to that pressure. When I go to brakes and the revs drop the accusump will start pushing back and keep the pressure up till the differential is corrected. If I am back on to the next straight in that time then the pump starts building the pressure again.
Options:
1. Am I making a mountain out of a mole hill? Leave it alone.
2. Plug that relief valve so it stays closed and let the oil cooler thermostat bypass the oil when its cold. This is a pre 76 case so there is the secondary relief valve by cylinder 1. Might be able just to invert the piston so the bypass grove is below the bypass passages.
3. There is also the high pressure pistons sold by pelican parts and others. Does this just shift the bypass window to a higher pressure range?
I would love to hear people's thoughts on this.
Miguel
Chris,
Seems like you and I are the only ones actually interested in the subject.
BTW motor is back in and I'll be mounting the cooler later this week. I order the high pressure kit from PP yesterday. Going to be in Daytona for a Chumps race this weekend so get her running before next week is not going to happen.
Miguel
Thanks for jumping in Randal! I was just at folks
I guess I could have been clearer with my original post. Where the accusump input is isn't the problem; its the oil relief valve that acts to bypass the cooling loop. Oil pressure above 35psi will essentially cut the flow to the cooler. Hot oil goes directly to your crank and gets hotter.
An accusump works as an oil pressure dampener. If the oil pressure stays above 35 psi the cooler never gets a chance to cool the oil. At some point viscosity gets critically thin and then it starts passing through the cooler. But this might be to late; the oil might already be burnt or below a healthy viscosity.
Its apparently a common problem when using a 30mm pump. I had no I idea at the time but my first trip to the track with my 914 resulted in this. After a 20 min session on track, driving through the pits my oil pressure warning light would come on at idle. I had to keep the revs up just to maintain 10-15 psi! A little stressful. When I checked my oil the dipstick looked completely dry!! It was so thin it would not cling to the dip stick. I freaked out and added 3qts to the motor. When I checked again after a few minutes the dipstick showed 3qts high! I had to drain off the excess oil which was black after just one session (it was new oil with zero miles before the session.)
I am just piecing the puzzle together now that I am researching the inner workings of the oiling system. (914 noob here )
And no my oil temp gauge was not functioning. An issue that is being resolved currently.
There is a thread on the Samba from a while back that covers the high pressure pump issue well. Its for VW 1600 motors but their oiling system and the type IV are very similar. Check it out here >>> http://www.thesamba.com/vw/forum/viewtopic.php?t=280293&postdays=0&postorder=asc&start=0
I have since swapped out the 30mm pump for a 26mm pump. But I am worried that the accusump will cause the same issue.
Hopefully I was a little clearer this time.
Regards,
Miguel
Hey Miguel,
I don't have much to offer regarding the cooler, etc. unfortunately. But I will be at Daytona this weekend. I'll be racing with the gunmetal grey Mustang. Come by and say "hi" when you get a chance!
What does your e30 look like? I drove one at Sebring last year - those things are bulletproof, easy to drive and pretty quick. I was very impressed, other than the loose seat bolts and shock bolt that fell out going through turn 1. Stupid guys prepping the car - needless to say I won't be racing with them ever again.
Ill look for you George. Look for a PM from me with contact info.
Condor Speed Shop and MAD Motorsports are the two teams that I work/hang out with. You wont be able to miss the MAD trailer; its a 53' car hauler with MAD vinyl all over it.
Here is the car:
Ok so if I follow this right, I either already have the booster kit in or need it.
I will run just under 35 psi at around 220 degree at 60 mph. After several hours of this it has climbed to 260 degrees when I stopped to eat and let it cool down.
So I might be ahead of the game to add the booster kit and already plan on adding another oil cooler for additional cooling.
I've been doing a little noodling on this, and even machined into a crankcase to see inside the relief bore.
I'll post pics when I have an opportunity.
One interesting bit of evidence is a wear pattern in the bore from the spring which shows where the piston resided most of the time.
It was typically being pushed down by the oil pressure far enough to expose the cooler bypass opening.
Simply increasing the pressure resistance by using a longer piston/spring only moves the problem to a higher pressure but does nothing to solve the basic problem of oil bypassing the cooler at operating rpm.
However, there appears to be a simple "drop-in" solution which I can test in the next week or two.
My solution replaces the pressure relief piston and spring, but not with just a different piston/spring.
I plan to make a sleeve which blocks off the cooler bypass circuit, but not the sump return circuit.
The sleeve will hold a smaller diameter piston/spring designed to bypass anything more than about 60psi back to the sump.
That way the cooler will always get oil flow but never see pressure above 60psi.
You are not the only one interested:
http://www.914world.com/bbs2/index.php?showtopic=217063
And:
http://www.914world.com/bbs2/index.php?showtopic=56102&hl=cooler&st=240
By running the oil cooler off of the oil filter bracket, I dont have the issue with it being bypassed at higher pressures.
I am also planning on running an accusump, just havent gotten to it yet.
Here's a little visual aid:
Relief valve components installed.
Notice the wear from the spring.
Relief piston in the closed position.
Relief piston positioned where spring marks begin. Shows cooler bypass open.
Here's my prototype pressure relief which eliminates the cooler bypass.
The opening pressure is estimated at 60 psi. Fine tuning may be necessary, and is done by varying the piston length to change spring preload.
Added features not shown include an o-ring seal at the top, and a screw to retain the spring.
The head of the screw will double as an alignment feature so the bypass holes line up correctly. (weld build-up visible was intended as the alignment feature)
I think we have a winner here!
We just ran the first test in an engine and the results are exactly what I had hoped for.
I just might.
Though this should get its own OT topic I'll give a short blurb here. We finished 6th at Daytona, two of our drivers had never been on the track before, and one of our drivers developed a fever while driving his stint. Had it not been for two silly penalties we would have been in the hunt for 1st place (15 min worth of penalties at sub 2:30 laps makes up the 6 lap differential at the end.) GRRRR.
Not bad for a team and car's first race! We are quite ecstatic to say the least!
Also I got to meet the George, the PaintedMan; which was cool.
OT race report over.
Mean while back on the 914 front I am excited for Chris's new solution to the oil cooler bypass issue! A week and a half away from getting to test it! Man its going to be hot at Sebring too!
Regards,
Miguel
Well, get on it!!
See you there.
Shane
[/quote]
Cooler installed!
[/quote]
Miguel
Let us know how this works out for you. When I installed my Tangerine Racing street headers, it moved most of the plumbing to the drivers side. I thought this location would be perfect. When I didn't see much improvement, I realized that I was probably picking up a lot of engine heat from the impeller. I moved the cooler higher and added a NACA duct on the right side rocker panel. Not sure how effective that is yet, but Foley has used that position with positive results, he says.
I have a feeling that all the talk about rear mounted coolers being inadequate has more to do with this cooler bypass circuit than anything else. Between accusumps and high pressure pumps I think most track type iv's have been shooting themselves in their proverbial feet.
Thanks to Chris we might have a solution on our hands here.
Next weekend will be a good test of this. We shall see
Miguel
Hey Miguel,
What was you track temps at the last event?
Shane
I think he said he didn't have an oil temp gauge installed before?
The new vdo gauge and the old sender were a mis-match so I had no data. It was wicked hot though. Swapped the sender last night so we will have data this time.
Hey Miguel,
Did you install a pull-thru fan? I wonder what will happen at idle? What will the oil temps do?
Just a concern with eliminating the stock cooler. We will know soon enough...
Shane
No puller fan. It's a race car, it should not have to idle too much once it gets up to temp.
Some racer friends came over last night and we got a bunch of the car buttoned up. Today after work another friend came over with his scales and we corner weighted the car. 2166 with my full figure in the drivers seat. 50.2% cross 51.8% rear. Pretty happy with those numbers. That's puts me pretty close, weight wise to where I need to be for HSR.
Went through the whole accusump priming routine. Filled up the oil sump. Added extra for the cooler and fird it up. I let it idle for 10 mins and it did not break 150. With some higher revs I was able to get the gauge to approach 170. Did that for a little while and gave up on getting it to heat up. The cooler was warm to the touch and the gauge was reading, works for me.
I still have a few details to sort out but the bulk of the work is done. Will be ready for next Sunday in no time
Bill, your words were prophetic!
Got to Sebring Saturday afternoon. Found Shane in the usual spot on the paddock. And began to unpack. Registration and Tech with Chin was a breeze. We were set for a nice day at the track. Little did we know there were gremlins laying in wait for us.
The long and short of temperatures was with the distraction of what was to come with oil pressures we got very little data on the cooling and the cooler bypass blank off kit. Between the rusty relief valve that was in the motor when purchased and a still unknown oil pressure issue I was not able to enjoy even half a session. We will try again in two weeks though so stay posted.
Sunday morning after the drivers meeting there was an open track warm up session which I was going to use to get in the grove before my evaluation session (first time running with Chin.) I could not even complete a warm up lap before my oil pressure dropped to the floor!!
As I idled in and through the pits pressure came back. 65-70 psi at idle. I thought maybe there was an air pocket in the cooler circuit and now its gone; head out and keep an eye on it. Nope, I got as far as Bishops Bend this time and the pressure disappeared. Idled in and hoped I did not do any serious damage.
A discussion among the friends on hand and we decided to check the pressure relief spring assembly. What we found was shocking to say the least.
Yep that is a rusty and scored piston and spring. If you have not inspected your oil pressure relief system in a while now is the time.
Our best guess of what was happening was that with the high oil pressures the engine was making the relief valve was fully extending and getting jammed open. A little jostling around and it would release. I had a new Weltmister high pressure kit on hand so that was swapped in. Ran a session with the fresh Weltmister piston and the rusty spring. Started to see ugly pressure drops after a few laps so I returned to the pits.
At this point we decided to test out the Foley blank off sleeve and piston. Very nice fit and finish. (I did not photograph it but I'll pull it out in the next day or two and post a picture here.) Ran a few more laps before the oil pressure light came on. At this point we were starting to suspect something else was causing the pressure drop off issue. The oil was hot but not hot enough to cause the massive pressure losses so soon.
For the four session we played around with some shrouding to block off hot exhaust wash from the headers entering the cooler. No significant change to oil temps. Pressure drop caused me to come in after 11 mins on track
Fifth and final session I decided to take it easy take a Sunday drive; it had not blown up yet might as well relax a bit and enjoy what was left of the day. More of the same. Got 16 mins in this time.
A big thanks to Shane and my friend Mike for coming out and lending a hand!! As usual Chris Foley's support and advice has been wonderful.
We have a few areas were I am going to look for the problems. Hopefully the gremlin will get sorted for the next track weekend. Stay tuned.
Miguel
This was my first time at the track with a completely new oiling system in 1997.
We drove 7 hours so I could hang out under the car all weekend.
At least I had the sense to rent garage space in advance, so it wasn't unpleasant, just discouraging.
I wish I could of been more help. Managing my Dad all day was a bigger challenge then I thought.
How did Warren's test go?
(pics of 914s in the paddock where they belong )
Attached thumbnail(s)
Nice pic. Looks like we had a private test day at Sebring.
Miguel
Track Test Report:
Was back up at Sebring this weekend with my 914 facing the grueling heat of central Florida in June. Surface temp of the track was upwards of 127 deg F when I measured it at mid day after one of my sessions. It was hot.
The cooler and pressure relief kits did their jobs well.
First thing I need to mention is the error in my VDO gauge. At the end of a 25 minute session the gauge was indicating 260 degree oil temp. As soon as I arrived in my pit I measure temperatures in several locations, oil cooler fins, tuna can, crank case sump (aluminum), and oil filter. Not a single one of these approached 260*. The closest reading was found on the cooler and the oil filter and they read 220*. That's a 40 degree error, on a new gauge!!
Temps were as follows:
oil cooler 215-220 depending where it was measured
Tuna can 180
Crank case 190
Oil filter 220
The oil pressure issues I was having were solved and were probably due to installer error in setting the acussump pre-charge.
While making changes and tweaks to the oiling system I closed off the top portion of the oil cooler box and added a scoop to the bottom to try and avoid picking up exhaust wash. Additionally I added a fresh air duct from the fan in the front valance to the cooler box.
The difference between the current set up and how Chris supplies the kit on track really only came down to how quickly the oil came up to its peak temp of 220. Without the extras the temp would come up to 220 within 3-4 laps and with the extras it would take 5-6 laps. If 220 is the ideal operating temp, which some folks promote, then the extra work was in vain.
I like that I can get a little extra cooling while idling back to my pit stall.
Throughout the session I was checking my oil pressure. Better than 50 psi was observed from the start of the session till the end. Only at idle rpms while heading back to the pits did the pressures drop. With the block off sleeve in place I am certain that all the oil running through the galleys first went through the cooler.
I am very happy with the results. If I end up with a bigger motor or a 6 I may have to swap to a front mount cooler. But if it could handle a 25 min session at Sebring in June I think it can handle just about anything its going to see with me at the wheel.
I was only able to run a session an a half as I developed a fuel starvation problem on Saturday afternoon. So now there is a new problem to address but at the least I have an oiling system that is up too par. Thanks Chris!!
Miguel
Miguel. The numbers when exposed to oil usually show higher. The dipstick gauges take a reading very close to the stock senders and usually show numbers close to the gauges unfortunately.
I think the mass of the case and insulation qualities skews the numbers some.
It's worth borrowing a dipstick gauge to confirm
I would tend to agree. Though VDO gauges are notoriously inaccurate in all forms, your oil temps probably were higher than 220, though perhaps not 260.
The point of the fins, sump, filter, etc being exposed to air is that they should always be cooler than the oil. The principles behind heat transfer dictate that the object (fluid) with higher heat gives off that energy to the next surrounding object.
I would definitely be curious to see the difference with a dipstick thermometer though. Does anyone still make those new?
Glad you're figuring things out though Miguel. The work that you and Chris have put in is something that we're all benefiting from for sure.
I think they are still available new.
Manley? Brand or something
I ran 240-250 in the afternoon sessions. Did an extra cool down lap and got back to 230 before the pits. It was hot out there, wow!
If the sessions were any longer, a front cooler would be the answer.
I see a cool 914 in the background in post #41. (behind the ugly dually)
I have an interesting anecdotal data point to add to the oil temperature discussion.
Over the weekend I was speaking with a 914 race car owner in PA who added a deep sump to his 2270 engine after a recent engine rebuild.
He claims the deep sump radiates enough heat that he barely gets to 220F oil temp now, whereas before, it often crept up past 230 on hot days.
So you think we could see a heat soaking issue where eventually the cooler can't keep up?
Miguel
[/quote]
Don't know. I wonder if the oil temp would of exceeded 250 degrees if there was more time in the session. That might be my operating temperature? Thinking about that Chin event coming up in July. They have that happy hour session. That would be one way to find out.
Here's a blanket question, are we worried about what a 914 engine can put up with or the oil viscosity breakdown?
Shane
[quote name='Jetsetsurfshop' date='Jun 26 2014, 11:50 AM' post='2054674']
So you think we could see a heat soaking issue where eventually the cooler can't keep up?
Miguel
[/quote]
Don't know. I wonder if the oil temp would of exceeded 250 degrees if there was more time in the session. That might be my operating temperature? Thinking about that Chin event coming up in July. They have that happy hour session. That would be one way to find out.
Here's a blanket question, are we worried about what a 914 engine can put up with or the oil viscosity breakdown?
Shane
[/quote]
I guess we'll find out if there is heat soaking ;D You got that big tank too. You think I could get the full hour in with my 15 gallon?
If you want to calibrate your gauge/sender, take them off the car and test in isolation using boiling water (210 degrees). You'll need a 12 volt power source. Dip the sender into the boiling water and see what the gauge says. It's a pretty easy way to see if your gauge/sender are at least in the ballpark of being correct.
Scott
Stack make great gauges. If you're gonna pull the sender, put in something quality...
Their http://www.stackltd.com/instruments_pro_control.html line does.
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