Congrats on the great #s, I have seen the oil pressure do that exact same thing before on the dyno and the cure was putting directional mesh or louver's in the pan. Front and rear splash shields don't do much in the way of stopping the oil that whip's off the crank from aerating the oil around the oil P/U. That is also the reason Buick put that splash shield that is held onto the main caps in there.
This is a 475 dyno'd on 91 pump gas with a small flat tappet, it had a work of art SRE pan with AM&P scavanger system on it. The only thing I did was install Steff's directional mesh and the O/P held flawlessly right to the end. Most people would never catch this unless they dyno'd it. I tried adding oil thinking it might be sucking the pan dry but there was no difference then removed oil thinking it was too high and getting into the crank with no change. I have seen loss like that from lifter hemorrhage also but I am guessing this is windage from the crank. I am confident that the loss is not the effects of oil temp here. Now is the time to fix it, I have 2 of those pans that is on your engine and they are both going to get oil control installed.
I agree, Properly controlling windage is something that a lot of people tend to overlook. I offer the directional windage screen or an optional louvered screen. I'll install them or sell the screens separately and allow the engine builder to custom fit to the application, (which is generally a better option). I find it very difficult to fit them to the pan and not guarantee that they won't need "clearancing" or "tweaking" at assembly time. That's why I try to sell them separately. It's also much cheaper because of the time required to fit them to the pan. It's not super difficult, but can be very time consuming. Steve
I run a Poston pan and had to install directional mesh windage screen also to keep pressure up thru the traps......where you need it most!
I have in total 4 of your pans here, the girdled stuff it is easy. I like the mesh and the bevel bars they supply are great to make into crank scrapers. What are the options on a non girdled engine because you don't have the girdle to hang it off I was wondering if sheet metal with louvers would work better then mesh in that case. Working around that pick up tube is painful. I bet there is a lot of people out there trying to figure out why they kicked there rods. Those factory shields work and that is why they are there, it floors me when I see guys re engineering there BBB by throwing them in the scrap pile, I just don't like how they trap the oil up in the crank so the only alternative is mesh or louvers if you discard the factory piece.
I figured they threw them away because they don't do a good job of tying the mains caps together (crack sat the mounting holes). LoL
It depends on how bad the mains move around. For the most part they will last fine, unless you start leaning on the block. Same deal with the oil flinger in front of crank timing gear, everyone loves to throw them away also. If you can't install that factory splash shield because the main caps are moving around to much then it might be a real good idea to concider a girdle. And if you must ditch it then make something to replace it, not only is it oil control but its HP gained if you do. Even when my 13.0:1 308S iron engine that ran 10 teens broke the main saddle that splash shield stayed in one piece some how. :Brow:
A few thoughts.. In regard to windage issues, never seen that be such a fast drop off. I have seen it, but it tends to start earlier, and be more gradual. I have one example for you.. this motor.. that I had the oportunity to dyno with and without a windage screen, and to document it. This is a stock oil pump engine, with internal pickup, and an SRE oil pan. Note the drop off in oil pressure.. We dynoed this one twice, and besides a bigger pulley on the supercharger, I also built him a windage screen, this solved that oil pressure drop off issue. Those are pretty easy with a girdle, they look like this.. Depending on where the rods end up in relation to his halo girdle, I would suspect a similar deal could be fabricated. Looking at just the oil pressure in a tight graph makes the difference obvious. We certainly like the second oil pressure curve better, and it shows the value of windage control. At the same time it needs to be pointed out that while it looks dramatic, we are talking about 10psi here.. The next motor I had oiling concerns with was Mike Erickson's 555.. Being the first production Tomahawk built, there were plenty of concerns with this new piece, and I initially was really disappointed in what we saw for oil pressure. A big drop off.. I was not happy with this at all, and we discussed the possibly of windage.. although Ron thought this looked more like lack of supply side volume to the pump, than it did aeration issues. This setup is a SRE pan with -12 external oil pickup/line to a TA Scavenger type oil pump. No windage screen. Time constraints being what they often are, I was unable to work with this at all, beyond raising the starting oil pressure to keep the pressure at the end of the pull in the acceptable range, and we limited the testing upper RPM Limit. I instructed Mike to watch the oil pressure like a hawk on the racetrack, if it does this on the track we would have to address it. He informed me that thru the traps at 6800-7000 rpm, it held 95-100 psi ... no problem.. and he proceeded to put 425 passes on that motor. So that made me tend to believe that, like he is so often, Ron was right... supply side issues. Oil level/liquid control in the pan, air leaks, aeration are the typical issues. When it came back for a freshen here, the first thing we did was take it back to the dyno.. I need answers on in-car performance vs what we saw on the dyno, and on this oil pressure thing.. we were able to figure out both. On the oil pressure, a graph makes it easiest to explain: Here is what your looking at: The black line, was the original oil pressure curve in 2011 when it was first dynoed. This was with 20-50 oil, actually Scotty had recommended that to me. Concern was keeping oil pressure when the alum block warmed up. I had artificially raised the oil pressure here to keep the terminal pressure above 60 psi. Remember, this is long before guys started running 50psi oil pressure in these blocks, and I am still not convinced that is a good idea over the long term. The Purple Line is the oil pressure it showed when it came back for a freshen, after 2 years and 425 passes. Still with the 20-50 oil. I had added an extra 2 quarts to the pan this time. By now, we knew it had to be a lack of oil at the pickup.. and since I wanted to try it anyway, we did an oil change and put 10-30 oil in it. The green line shows the result of that. It hung on better than I had ever seen this motor be capable of. With nothing more than a simple oil change. Now, armed with newfound confidence, we pulled this one on the dyno to 7000 for the first time. That's the red line... and while it still shows a drop off, the issue was oil level in the pan. This was later traced to an extra hole in the lifter body that should not have been there, pumping oil under pressure up to the top end, and the lighter oil made it back to the pan faster. Why did I see this on the dyno, and Mike did not report it in the car? Because, as testing haters are so happy to point out, the dyno is not the car.. Testing an engine in a stationary position, and then in a race car, when it comes to liquid control in an oil pan, could not be more different. G Forces kept the sump full on the pan for Mike, in the car, and there was no issue. Drainback was the biggest factor in this motor. I suspect that a similar issue may be happening in Dom's motor here. This is not Scotty's first rodeo, and he very well may know that is what is happening here, so he didn't even bother to menton it. Dom, just make sure you watch the oil pressure like a hawk from half track on... if it drops like this, fix it, before Steve's new oil pan has some interesting new holes in it.. But I bet you will be ok.. make sure you try and add some oil, if you did not do that on the dyno. When I first saw the oil pressure on this one, I noticed what appears to be an orange fram oil filter on the motor.. and attributed the drop off to that.. I have heard stories from Ron that he sees these filters plug up on new motors. But after thinking about it, I suspect the real issue is the situation it was tested in... a quart or two of oil in the pan would have answered that question. JW
Jim, u nailed it! I spoke to Scotty the following day and said it was due to the lack of oil getting pulled to the back of the pan. He had not mentioned it because it wouldn't be an issue in the car. I was too busy looking at HP and torque numbers during the pull that I didn't even notice. This was the first time I actually had one of my own engines on a dyno and I was kinda blinded by the whole thing. He said he used to dyno sometimes3 motors a day when he worked at Musi's shop so I have confidence he knows what's going on during a dyno session. You can I will have my eyes on the oil pressure once I get it down the track.
Mike, the picture that Jim posted is it. That's how it's done with a girdled application. Without a girdle I build them into the pan. I don't have any pictures on this new house PC, but I'll post some when I get back in the shop... likely tomorrow night. Jim, you did an outstanding job explaining the oil pressure drop situation. Very interesting! And you're absolutely right that windage is only a part of the oil control issues that we face. Getting oil back to the sump is imperative! The bottom line is to have that pickup submerged in oil at ALL times..... what ever it takes! Thanks!! Steve
I needed to run out to the shop for something so here are some pics on windage screens in the pan for non girdled applications. One is an internal oil pickup and the other two are external. Steve
As I posted above, in my situation I added oil and pulled oil out that is the only way to get a idea if its running out of oil, or if the crank is in the oil or if its a windage issue. In my opinion that is how you narrow it down, surprised this wasn't tried while on the dyno but either way the problem was windage with my deal and was solved by adding the mesh kit. I backed up and verified this by putting the engine back on the dyno after the mesh was added. It also can be effected by where the PU is in relation to the front and rear splash shields etc also. :TU:
Stick a go pro in side the car because you most likely ain't gonna want to make a high 9 second pass watching to see if the oil pressure falls off. :TU:
I really appreciate those very thorough answers. After seeing those pics, I can tell you I was over thinking it. I can't say that I've ever studied a dyno sheet close enough to remember ever looking at oil pressure as it relates to RPM. I've always focused on RPM, torque, and HP. Those are the fun ones aren't they? From now on I'll be looking closer at all the numbers on a dyno sheet. Thanks again guys.
