DUB

ok ok after reading it turns out that vac/boost gauges can't read the vac reading...



I was basing my quick response on the fact that I've spooled turbochargers with compressed air and place my hand infront of the compressor wheel and thought it was neat how much vacuum was felt...of course I not as accurate as a gauge definitely more vacuum than I'm capable of producing

DUB

dayem three posts in a matter of minutes...sorry.



"More than enough to open the little diaphram in the OMP nozzles though."



if they just need filtered air, how will the diapharm open???



OMP pushes oil thru line, vacuum opens nozzle.



I'd premix for safety.

ccarlisi

You're right, under boost there is a fair amount of vacuum. However, it should have no effect on the amount of oil that is metered in under boost.



The air valve only comes into play when the motor is operating under vacuum. The oil is metered into the nozzle below the valve. The valve is a simple one-way air valve, oil does not pass through it. Under vacuum the air openings on top of the nozzles suck air into the motor to prevent the vacuum pressure of the motor from creating a vacuum in the oil lines and sucking in excess oil. This is why a filtered air source is necessary, and why it is connected to the filter on the stock turbos. You can confirm this by unplugging one of the lines and putting your hand over it when the car is idling. You will feel the air being sucked into the line.

Several shops simply cap the air openings. It works, but emissions will go to crap under vacuum.



Under boost, the intake section of the combustion chamber is pressurized instead of being a vacuum. To compensate for the change in the pressure gradient between the oil lines and the combustion chamber the metering pump increases the oil pressure in the lines. Because there is no longer negative pressure inside the metering nozzle the valve remains sealed. If the valve does not seal when the motor is operating under boost, the motor blows oil out through the air valve. I learned this from personal experience.



The ONLY reason I think it may be necessary to connect the lines to a vacuum source is that the one way valves may close faster under boost if a vacuum force is pulling them shut in addition to the pressure being exerted on the other side of the valve by the motor. However, I have run them both ways and never felt a drop of oil come out of nozzles when they are not connected to anything, which tends to support my belief that vacuum is not necessary since any air passing through the valve before it is able to seal should be saturated with oil.

DUB

thanks for that explaination...you learn something everyday.



Good luck with the single install...I like the oil feed line! I'll be ordering one soon.

ccarlisi

UPDATE:

As I previously mentioned my custom downpipe is back ordered for several weeks. As a favor, Justin at Davinci provided me with a used downpipe he had at the shop on short notice. I test fitted it today and it fits perfectly with the Autochrome manifold. Both the weld work and mandrel bends look very nice.

ccarlisi

Before purchasing Justin told me about the v-band flange problem. The flange is created by flaring out the end of the pipe. Unfortunately the flange section is very narrow and doesn't seal well. According to Justin, the new Davinci downpipes have a thicker flange to solve this problem.



I was originally planning on lopping off the flange and welding on the flange that came with my v-band kit. However, I think I may have found an even better alternative (at least a cheaper/easier one). I took an old 3" exhaust metal exhaust gasket and ground off the edges for the exhaust studs. Next I positioned it in the v-band clamp, between the turbo flange and the downpipe flange to take up the excess space. With the modified gasket in place the downpipe forms a much better seal with the turbo, but it is still not perfect; the seal is not tight enough to prevent me from rotating the downpipe when it is clamped down. Bear in mind I used a gaskset that was in such bad shape that it was leaking exhaust around the entire circumference when it was installed between the cat and the catback. Tomorrow I am going to try again with a thick new gasket. If that doesn't work then it's time to fire up the welder



Here is a shot of the modified gasket. Please excuse my glowing hand, I grew up next to a power plant.

9BASE3

Hope all works out Chris! Nice hand.. Do you have to wear gloves when using the bathroom?

rdavidsrx7

damn you and your quick recieving/installation of your parts, I still got about 2 weeks to go

ccarlisi

I'mmmm back Hi guys. Since we last left off my AEM ignition amp failed in rush hour traffic in the middle of the expressway. Because I had to send it back I decided to put my tuning efforts on hold onto the replacement arrived. . . .6 weeks later with no replacement I decided forge ahead without it.



With Rich Ferrall at the wheel I did 2 hours of tuning tonight. Before the amp failed the car was tuned to 11.5psi. Tonight I brought it up to 14.1. For the most part it feels fantastic. However, at that boost level the motor frequently stumbles at high rpm at anything under 11.5afr (the highest value I felt comfortable leaning it out to).



Here are my thoughts:

-The 9 heat plugs are only a couple days old so I do not think they are worn out. However, I have hit a bunch of pig rich cells with them (afrs of 9.5-10), so they may have fouled out. I am going to pull them tomorrow to see if that is the problem

-Maybe the car cannot run at 11.4-5 afr without an ignition amp at 14psi. As I recall my car with the stock twins had the same problem without an amp when Steve Kan tuned it.

-Maybe the wideband sensor is worn out and is reading lean (meaning it's really 10.8 when it says 11.4). Since the Bosch sensor is only $35 and has about 10,000 miles on it I'm going to replace it just to be safe.



If anybody has any thoughts or can help me rule anything out please let me know. Once I get this straighted out I'm going to move up to 15psi and then hit the dyno to generate some numbers!

Cheers!

My thoughts are stop using the AEM ignition amp. Stay away from all AEM products. Go with the tried and tested MSD or Crane setup, why monkey around when the rotary community knows and has proven the MSD/Crane setup works.



What about aftermarket MSD blaster coils or Crane LX92 coils? Or the new rx8 Bosch coils. I know people keep on saying the stock coils especially on the 2nd gen turbos are super heavy duty, but coils do wear out and htey do go out of spec. My did.