Oil consumption question for Roe sc cars

[riverflyer]

Since adding the Roe kit to my car I have been really going through the oil. It seems to be blow by. I live in Cal. and have been running 91 octane except for track days so have been running the 9degree card. Sean thought valve cover breathers might reduce some of the pressure, but I have not tried that remedy yet. Valaya racing has some recirculating mods that they can add but I am wondering what others have done or experienced in regard to oil consumption. I have a 99, low miles and very well cared for car. This week I made two trips with oil consumption carefully monitered and went through 2.75 quarts in 230 miles of spirited driving with about 150 miles of it under hard throttle, and only occassionally getting into 4th gear. Most of the miles were in third. Would appreciate any feedback as I know there are some very good tech minds here on the board. thanks, John

 

[1TONY1]

How is your crankcase vent done now ? I would say: Check compression then do a leak down test, but first I want to know about the ventilation. If you are using the stock ******* on the front of the valve covers, get out the drill and plant the breather on the front top of the drivers side valve cover. Stock breather box ? VIPAIR ?????

 

[Nadine UK GTS]

I have the same problem, not helped by the fact my rings are worn, but the SC blocks off the OE crankcase breather port, I don't thing this is a very good idea at all! If any one has found a way around this then please share, I would like to be able to vent the crank again too (not the only venting being through the valve covers!)? Re valve cover breathers, I drilled and fitted larger top breathers, besides needing larger breather ports it stops the oil-puke problem under braking you get with the OE front ports. I also vent these into a breathable catch tank. If you plumb the valve cover breathers into the air inlet system you will vent oil mist into the SC and inlet manifold...greatly increasing the risk of 'ping'...ouch! The filtered Moroso type option supplied with the kit will solve this and allow you to connect the valve breathers to air inlet tubes and air box (use one each side). I had to tie my dip stick down, or it blows out!

 

[JimT 99RT]

1Tony1,

I am installing the Roe kit, so I take it that you recommend using the supplied breather in the kit and mounting it to the Drivers side valve cover. I have the Roe modified stock air box for the 3" smooth tubes and 70mm throttle bodies. Do you have a comment about Nadine routing the tubes to a breathable catch tank verses back into the air intake.

-Jim

 

[SUN RA KAT]

I used less than 1/2 quart in 3,000 miles. I have my valve covers vented to the passenger side of the Roe 70mm airbox.

 

[Sean Roe]

#1, the fix. Choose option 2 or 3 from the installation manual. Here it is for your review:
..........................................
(61) Now we need to setup the crankcase breather system. You have a few options available depending on your use of the car and the engine condition. We found that under hard acceleration with the engine hot, dense oil vapors (blow-by) can contaminate the intake air, which in excess could cause detonation (with or without a supercharger). Some cars have more blow-by than others.
Option #1: Locate the crankcase vent hose assembly with the two 90 degree fittings and two of the black hose clamps (In the same bag from box #4). The vent hose will make the connection from the passenger’s side valve cover to the passenger side air intake tube fitting at the side. This hose assembly has a restrictor placed inside one of the two 90-degree barbed fittings. This option is intended to allow positive crankcase ventilation. Install the hose and use the clamps at the valve cover and intake tube fitting ends. See picture #8
Option #2: Leave the original valve cover breathers in place, which run together to the air filter housing. If you choose this option, you will need to cap the inlet fitting on the passenger’s side air intake tube. You will find an extra cap in the bag inside box #4. This option is beneficial to an engine that may otherwise pump too much oil into the intake system.
Option #3: Use the push in valve cover breather found in box #4. This requires putting a hole, slightly less than 1.25”, in the valve cover. If you do track events or your engine has an excessive amount of blow-by (worn rings), you should install this breather in the forward upper corner of the drivers side valve cover (determine the proper location by looking at the valve cover from the inside). It’s not necessary for regular street use.
Use the supplied short hose and union to connect the breather to the air filter housing hose. Block off the original valve cover breathers and air intake fitting on the passenger’s side tube.
Additionally, if doing track events, we suggest the following:
- Use race gas.
- Put a tie wrap on the dipstick handle to hold it down.
- Consider installing a second valve cover breather.
.....................................................

#2, the supercharger installation does not mean we have to cap off the crankcase fitting in the engine valley, but we choose to block it because it slings too much oil out. This outlet is also very small and goes through a PCV valve one '96 & '97. In '98 and newer, there's no PCV valve, but they reduced the size of the fitting to 0.210" inside diameter. You can use a 90 degree fitting here if you want and it will fit under the intake manifold, but I wouldn't recommend venting it into the intake.

#3, the dipstick on '96 engines does not have a positive seal / lock as the '97 and newer models do. SC or no SC, if you push a '96 engine hard for a while, it will push the dipstick up unless it has large valve cover breathers added to it.

#4, here's how the stock crankcase breather system is designed to work on Gen2's and why Vipers usually **** oil into the intake on decelleration.
1. Filtered air travels from the tube on the drivers side of the air filter housing and into the engine through the valve covers.
2. Contaminated crankcase air is sucked out of the small fitting in the valley near the thermostat and into the intake manifold, behind the throttle bodies where vacuum is high.
3. When you run your engine hard, it builds up crankcase pressure because these three vents are very small relative to the 488 cubic inches of the engine.
4. After running the engine hard and letting off the gas at 5,000+ rpm, a tremendous amount of vacuum is generated due to the engine revs being high and the throttle bodies being closed. The natural occurence is for the crankcase air, now contaminated with heavy oil vapor, to be drawn into the intake manifold. When getting back on the gas next, this oil will be drawn back and into the cylinders, causing blue / white smoke and detonation.
A factor in all this is the size of the crankshaft journals relative to the width of the block. The crank is acting like a fan inside there and the narrow block design does not allow oil to pass by easily, thus holding it in suspension.

These are some of the things we've seen over the years and I hope it helps shed some light on the situation.

Regards,
Sean

 

[riverflyer]

OK, thanks all. Sean, I never saw the install. manual, must have not made it back from Valaya. Anyway, I appreciate the written explanation as now I understand several issues going on with the car. I found #4 very very helpful and since I live in the coastal mountains with lots of steep twisty canyon roads, the throttle conditions you described are very descriptive of my conditions. Will it hurt to drive it until this problem is corrected? And once it is corrected, should I change out the plugs? Anything else? Thanks, John

 

[Sean Roe]

You shouldn't need to change plugs, but I would suggest option #2 at your earliest convenience if you like to run the car hard. It doesn't take any tools to install and you should have the parts.

 

[1TONY1]

1Tony1,

I am installing the Roe kit, so I take it that you recommend using the supplied breather in the kit and mounting it to the Drivers side valve cover. I have the Roe modified stock air box for the 3" smooth tubes and 70mm throttle bodies. Do you have a comment about Nadine routing the tubes to a breathable catch tank verses back into the air intake.

-Jim

Hey Jim, I originally used a K&N valve open cover breather in the oil fill hole. Worked great except for the smell of fumes.....it was right next to the air intake for the hvac. So I changed to using the ******* at the front of the valve covers to the factory air box. I noticed some detonation and when autocrossing (using spirited braking) oil was getting in the airbox, so much that it would run out of the airbox and puddle on the ground and blow back on the front of the engine. As bad as I hated to I put the hole in the valve cover and used the supplied breather and ran it to the airbox.....the hose going to the airbox is staying dry as well as the airbox. I want to check to see if there is any vacuum at wot (wide open throttle) on that hose. When reving the engine sitting still I cannot feel any suction on my thumb from the airbox ******. Future goal is to put another breather in the passenger side to match the drivers side and run to a small puke tank under the airbox. The puke tank will either have the K&N breather on top or have a hose on top going to the airbox. I will also investigate using the electric vacuum pump from a Camaro/Firebird to the top of the puke tank to see if one or two of them can maintain vacuum under wot. In most cases the single breather will be fine.