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Article in June GRM (Pro vs. Joes) talks about Miata tuning. One issue discussed is using low viscosity oil and running a half quart low to get a bit more hp. I thought the consensus was to run high viscosity oil and to run a quart high.
Your thoughts?
I think it depends on how much you like your engine and how confident you feel in your oil pressure.
If you are rebuilding your motor every season, sure run lower viscosity and low oil, you will make a few more ponies.
On the advice of several mechanics, I run Mobil 15-50, and about a 1/2 to full qt over. So far so good but hopefully the motor will hold together.
The only time I see pressure issues is coming off track driving thru the paddock and the motor gets down to idle, pressure drops and the light on the dash flickers. I rev the motor and the pressure goes right back up.
Does anybody else have this issue? Any ideas what it could be?
I have an oil pressure light that goes off sooner than the dash light. After a session is the only time I see it go on pretty regularly. It flickers on the track, but always in the same spots (if it were to go on in a new spot, I reach for the key, if you know what I mean). I do run a crank scraper.
I have the idiot light on the dash and the oil pressure light working off an adapter in the stock oil light port (near the filter). I have NEVER seen the stock light go on - except at start up, so I know it works.
I run AMSOIL 20-50 just shy of the full mark with a crank scraper and never see the stock light come on (except start up). Occasionally got the light before the crank scraper.
Probably worth playing with lower viscosity for those last couple horzpowers, but not worth it for most…IMO.
running a quart high or not depends on how much you want to protect your engine. Having a crank scrapper helps gain back some of the power lost to running the oil high.
thanks,
bruce
87isMan wrote:
Scott,
It is possible to free up a few HP (maybe 3-5) by choosing lighter weight lube, more slippery lube, and using less oil in a particular unit (motor, trans, diff). Frankly though, I don’t think a few few HP is worth the risk. Particularly for those of us who are running box stock engines with well over 100,000 street miles.
Skeen has shown that he is plenty fast with 20W50 synthetic, John Black’s car makes good power with BMW labled Castrol 10W60 synthetic, and we have seen the dyno charts of many front runners that prove the rear wheel HP of most of the front runner’s cars are within a few percent of each other. I have head of a few guys running low oil levels but with an Accusump to provide consistent pressure in the tight turns.
The pro Miata guys the article references are most likely running newly rebuilt balanced and blueprinted engines with tight tolerances with whatever trick component that they can find. So they can run a 20wt race oil and maybe light oils in the trans and diff to make a HP or two. The front runners very likely rebuild their components every 30-50 hours as well. In contrast, our 2.5s were designed 30 years ago when oil philosophy was “thicker is better” and most Spec E30 motors have never been opened up. That being the case, ultra thin oils and low levels are a big gamble unless you plan to rebuild your componenets every year.
I happen to run Amsoil 10W40 and Amsoil synthetic gear lubes in the trans and diff and my car makes normal power compared to the dyno reports that were floating around from last year’s nationals. I don’t have a crank scraper (yet) nor a accusump (yet). I run with the oil at the full mark. While my car only has a couple of races on it, it has a lot of track miles on it and has never been apart. I am convinced the synthetic oil helps over conventional oil but to be honest, I can’t prove it. I have used oil analysis many times and so far the results are good but that is not to say the results would not have been just as good with conventional lubes.
What’s the point? Don’t risk your engine for the sake of a HP or two. Having said that, if you want to try Amsoil products I am a dealer and can save you a few bucks.
Don
87isMan wrote:
I plan on the Ishihara-Johnson crank scraper from Factory 3 Racing. You can find scrapers at Ireland Engineering and Carr Engineering too.
I’ve got a well worn engine (+270k) with the IE scraper and a newer engine (~80K (in the car now))with the IJ scraper. Both seem to work about the same, with perhaps a slight edge to the IJ variant. Factory 3 has the IJ scrapers and if you are putting one in that’s a good source for a quality product. The design of the IJ unit looks to be a bit better than the IE unit.
Thanks Don for the extensive reply. I wasn’t so much hot to run low and runny on oil, I just wanted to make sure that I correctly understood what the consensus was.
I had my bottom end replaced in Mar. and Chuck Taylor’s crankscraper installed at that time. My motor has ~165k on it. Like Kevin (Jones) I run high viscosity Mobile 1 a quart or less high. I add a 1/2qt after a hard day on the track. I’m also starting to change my oil filter after every couple of events (which is to say monthly). Changing the oil filter more often certainly makes the oil look better.
I’ll probably change my oil at mid season and at the end. At 6 track days/month, I figure that I add enough oil at events to equal an oil change every 2 months,
How often do the rest of you guys add oil?
Ishihara Johnson Crank Scraper. As Don said, 10W60 about 1/2 way between the marks on the dip stick. I change oil every 2 events (but with Natalie driving too, we have a lot of use on the car in a weekend). Engine spent 75K as an automatic attached street car - the last 10K as a Manual attached track rat. I think from looking at Dynos, I’m near the top end on power - not the highest, but in the top 15%…
I have a brand new Ishihara-Johnson Teflon crank scraper for sale. It took them almost 2 months to ship it to me, but I can ship yours right away. Looking to get what I paid - $189.95.
-Vic
Ranger wrote:
[quote]Thanks Don for the extensive reply. I wasn’t so much hot to run low and runny on oil, I just wanted to make sure that I correctly understood what the consensus was.
I had my bottom end replaced in Mar. and Chuck Taylor’s crankscraper installed at that time. My motor has ~165k on it. Like Kevin (Jones) I run high viscosity Mobile 1 a quart or less high. I add a 1/2qt after a hard day on the track. I’m also starting to change my oil filter after every couple of events (which is to say monthly). Changing the oil filter more often certainly makes the oil look better.
I’ll probably change my oil at mid season and at the end. At 6 track days/month, I figure that I add enough oil at events to equal an oil change every 2 months,
How often do the rest of you guys add oil?[/quote]
Who is Kevin?
Jones wrote:
That’s your new name. Just like my new name is Yee.
…the one that used to be Chi…
Jones wrote:
[quote]
Who is Kevin?:)[/quote]
Hmm. Sorry Brian. Not sure what I was thinking there.
Jones wrote:
[quote]If you are rebuilding your motor every season, sure run lower viscosity and low oil, you will make a few more ponies.
On the advice of several mechanics, I run Mobil 15-50, and about a 1/2 to full qt over. So far so good but hopefully the motor will hold together.
The only time I see pressure issues is coming off track driving thru the paddock and the motor gets down to idle, pressure drops and the light on the dash flickers. I rev the motor and the pressure goes right back up.
Does anybody else have this issue? Any ideas what it could be?[/quote]
Brian (or should I say Kevin?),
Same here - I’m running Mobil 15-50 on a rebuilt engine at 1/2 quart over full. My adjustable op light is set for about 15-18lbs and comes on in the paddock when the motor’s hot. Apparently this is normal for E30s.
On the other hand, when I saw that same light come on in Turn 5 at RRR last year, it marked the beginning of the end. I made it through the next event at Barber but by then op was getting non-existent at idle. Turns out a main bearing was about to go.
–Fred