VTEC problem

[menfou]

Hello,

October 2013
My NSX made more than 500whp with 18PSI , and no problem on Track.
I used Mobil 1 5w40.
Oil temp was 110-120°C(230-248°F)

Friday
I changed my oil and oil filter, I choose Mobil 1 10W60

Sunday
I drove my car on Track, and in 3rd or 4th my car didn't pass 6000rpm, for me the VTEC didn't work, my AF is under 10:1 instead of 11.5:1
Oil temp 105-110°C(220-230°F)
I return to paddock and made some tests.
1/ I checked my solenoid, I can listen a "click" sound when I put 12volts on the solenoid.
2/ I put the VTEC at 4000rpm with no load, no minimum temp, no minimum speed.
I checked with a ohmmeter the vtec pressure switch, I have 0 Ohm before 4000rpm, and > 2M Ohms after 4000rpm, so for me the VTEC is ON.

Yesterday
I put my VTEC back to 5000rpm with minimum speed and load.
I drove my car on road with 2 ohmmeters, my oil temp was 90°C(194°F)
I have 0 Ohm before 5000rpm, and > 2M Ohms after 5000rpm, so for me the VTEC is ON.

Today
I think to remove my solenoid, clean the filter.
Change my oil with 5W40 or 10W40.


I think the 10W60 is not good for our engine, what do you think ?

 

[A.S. Motorsport]

10w60 is dangerous!
It's MUCH to thick for a V-Tec engine or any other normal Honda.
Max you'd thickness you'd want to run in a NSX is 10w40

Stay between 5w30 and 10w40
Honda recommends u use 10w30.

I've seen a perfectly fine 3.2L get very badly damaged due to 10w60.
Many mechanics think because our Honda's run high RPM that we need thick oil, this is utter nonsense as the V-Tec system is designed for thin oil for it's oiling and passageways.
This also lowers friction and drive train loss in pumping the oil, to thick a oil will starve the small oil channels in your cylinder head!

On older Italian sports car it's opposite is true they need 10w60 to lubricate and build oil pressure.

 

[menfou]

Thank you for your reply.

It's strange but I think the same, our VTEC doesn't like 10W60 oil.

My oil pressure is better with 10W60(4-5bar) with 110°C oil temp
With 5w40 my oil pressure was 3-4bar with 110°C oil temp.

I thought 10W60 was better than 5w40 for high temp, but apparently it's not true for our VTEC engine.

 

[A.S. Motorsport]

Correct, this is the conventional school of though,
More rpm = stress = heat = thick oil requirement, due to the fact that Honda's are engineered for high stress and significant safety margin there recommendation is correct for even though use.
Just listen to what Honda says :biggrin:

I've heard it more that engines often just don't engage V-Tec with 10w60 in them.

 

[Aluminsx]

So did switching back to the thinner oil solve the problem?

 

[menfou]

Hi,

Yesterday I changed my oil with 5w40
It's difficult to say YES at 100% because my problem was only on Track with oil temp > 220-230°F, and only in 3rd gear and upper.
It's difficult to have oil temp > 220°F in winter on the road , it's impossible.
So I drove my car in moutain, after 10 minutes in moutain my oil temp was 230°F, and VTEC was OK in 3rd(it's very hard to pass 6000RPM in moutain and keep the vtec engaged until 8500rpm )

Today, I will drive my car again in moutain with my GOPRO , it's beautifull with snow on the sides.

 

[A.S. Motorsport]

Hi,

Yesterday I changed my oil with 5w40
It's difficult to say YES at 100% because my problem was only on Track with oil temp > 220-230°F, and only in 3rd gear and upper.
It's difficult to have oil temp > 220°F in winter on the road , it's impossible.
So I drove my car in moutain, after 10 minutes in moutain my oil temp was 230°F, and VTEC was OK in 3rd(it's very hard to pass 6000RPM in moutain and keep the vtec engaged until 8500rpm )

Today, I will drive my car again in moutain with my GOPRO , it's beautifull with snow on the sides.

Snow = cold air + boost = :biggrin:

 

[menfou]

Yeahh :biggrin:
But snow + sun = water on the road + cold air + boost => big testicle to keep vtec enabled in 3rd :biggrin: , sometimes "poop in pants"
You will see the movie tomorrow

 

[A.S. Motorsport]

Haha, it does get tricky then.

 

[ftuhy]

About 6 or 7 years ago when Acura was running in the ALM series, the head of the Mobil 1 development team did a presentation at Lime Rock for NSXCA members. It was a great presentation by a top-notch chemist and obvious car buff. He went into a lot of chemical formulas & reactions to explain the differences between the various types of synthetic oils and oil differences required for racing vs street use.

He shuddered when someone said they were using 15W-50 in their supercharged OEM NSX engine. He said the NSX has a tight clearance engine, and the molecules in the heavier weights are too large to properly flow through the bearings, etc. He recommended M1 5W-30 for street use, and I think 10W-30 (40?) for the track. He noted Honda recommended 10w-30 for the street, but said that was for dinosaur oil & before Honda certified Mobil 1 for use in the NSX. He noted that if an engine has been built by a good engine shop, the shop would recommend an oil weight based on their specific clearances, etc.

And that's all my write-only-memory can recall from that talk.

 

[Larry Bastanza]

Hi Frank and all,

I was there also and you are correct. He stated 10W30 as specified was fine, but also said no problem with 5W30 also for street, 10w30 was also good for track, with 10w40 as an option. The question was raised by me, since I had a heavily tracked NSX with a really bad oil smell when I did an oil change(had 10w30). I assumed at the time, the oil was burnt from track abuse, so I stepped in up to 20W50. He explained this was not a good idea, and if ever you get a smell like that in the oil it is almost always due to a poor load of fuel! He went on the state how fuel is the only thing that really mixes with the oil based on ring condition, etc. This NSX was heavily tracked and I immediately reverted back to 10W30, and the car is fine now 7 years later.

This guy was one of the original engineers that developed Mobil1. Pretty impressive.

Regards,
LarryB