[RallyBob]

Hmmmm, a reason to show myself on this forum again. Interesting bantor.

Mr Dennard, I enjoyed reading about your insight into the workings of a competition Opel engine (on your website). I look forward to the end result, and have no doubt the magic '200' number can be broken with modern technology being applied. Good luck.

Bob

 

[RallyBob]

Bob, just curious, are you going to run a drysump on this engine?

 

[RallyBob]

TGSI, your timing is impeccable. I just yesterday welded an AN fitting on to the timing cover for my GT-4 engine (my friend's car, but my engine...for regionals only). I actually ended up grinding the oil filter boss off the timing cover, and tapped the center return hole (normally filter thread boss) for a 1/2" pipe-to-10 AN fitting for my oil line. The feed line is on the opposite side, just below the stock fuel pump boss. Here I welded an aluminum -10 AN fitting for the feed to my remote filter/thermostat/oil cooler.

While I did not bypass the pump in my setup, I have adequate knowledge of the oil passages to be able to suggest where to tap into. Best bet would probably be to simply use multiple scavenge hoses at the bottom of whatever oil pan you devise, and feed the oil from the pump (or cooler actually) into the timing cover @ the oil filter threaded boss. You will need to drill/tap to plug the OEM filter check ball, and then weld or plug the OEM feed line from the filter area. I chose to grind the port away and plug the passage elsewhere.

I will be photographing my cover tonight, and will post it soon thereafter.

Bob

TGSI, if push comes to shove, I could also photograph Tom Drake's dry sump system on his GT-4 car for some ideas.

 

[RallyBob]

Regarding the timing cover/oil system mods I spoke about earlier:

Here is a closeup of the relocated 'output' or pressure side of the oil system. This will run to the remote filter, then to the thermostat and cooler.

 

[RallyBob]

This is the return side, coming from either the thermostat or the oil cooler, dependant on the temperature of the oil. This would normally be the center of the oil filter. Just adjacent to the AN adapter, the OEM press-in plug and oil filter bypass have been removed and tapped for steel pipe plugs, ensuring no leakage.

 

[RallyBob]

This is an overview of the cover. The fittings I'm using are Aeroquip Socketless. They are far cheaper than normal 'cutter' style Earl's or Aeroquip style fittings and hose, and the hose itself is far lighter. Not stainless braided however, so careful routing is required to ensure they are not cut or worn through.

 

[RallyBob]

I'm now confused, when does the oil go to the engine bearings? The stock path, I thought, was from the pump to the filter and out to the bearings. I'm confused where the oil goes now, after it leaves the pump.

Paul

*****On a standard engine, the oil is drawn from the pickup tube in the oil pan first, it travels through a drilled passage in the block to the timing cover. From here, it is fed to the 'in' side of the oil pump. Then, under pressure it leaves the pump (smaller passage BTW), and heads to the oil filter boss (the open, odd-shaped passage at the perimeter of the boss). It enters the filter here. Now, should the filter be blocked for some reason, the oil will overcome the ball and spring in that oil filter boss, and be directed into the engine unfiltered. However, normally the oil will travel through the filter, and be forced under pressure into the center threaded portion of the filter boss.

Directly after this, the pressurized oil gets distributed to the engine. The largest main passage feeds the bearings. A very small hole feeds the front timing chain lower gear, another small hole feeds the hydraulic timing chain tensioner. A slightly larger hole goes upwards and feeds the head (cam, rockers, lifters).

All I did was intercept the pressurized oil *before* it headed to the filter boss, and directed it to the remote filter/thermostat/cooler. The return side of my lines goes directly back into the normal filter boss passage. Simple.

Bob

 

[RallyBob]

Sure. Watch for adapters. Some are restrictive and block flow badly. I try to get good ones and still end up 'porting' them to reduce sharp transitions.

Also, get a good oil cooler.....cheap ones suck. My friend had a cooler on his ITB race car (inexpensive one), and the car ran hot oil temps (260-270). Switched to a Mocal that was half the size of the cheap one and the temps dropped 30 degrees.

Also keep in mind that having 210-230 degrees oil temps makes a noticeable increase in power on an Opel engine versus oil that is too cold.

If you see cooler weather, use an oil thermostat. Oil that is too cold will reduce power in the engine and promote wear. At least 180 degrees.

Think seriously about line diameter. A street engine (mild) can use -8 line (1/2"), but for more power/rpms I'd go to -10 (5/8") lines. A smaller line may theoretically keep the pressure up, but in fact the surface friction inside the smaller lines will restrict flow and reduce pressure, especially at the juncture of the fittings. Not merely my opinion, but rather it was explained to me that way by a fluid dynamics engineer. Keep away from sharp 90 degree fittings, I like to use 45 degree and 90 degree 'tube' fittings when I have no option (as shown in the photo above).

Bob

 

[RallyBob]

Thanks TGSI for the words of encouragement. You are correct on blocking the OEM pickup tube passage for a dry sump, otherwise you will either leak oil back and/or draw air into the system from the crankcase. The only situation that must be accounted for otherwise is that oil spray passage for the lower crank gear. I spoke with Tom Drake today and asked about his system, he seemed to recall leaving the existing oil pump housing intact to allow for this pressure spray, but blocking the main passages so they don't leak to 'nowhere'. I suppose in your case the entire OEM oil pump housing could be milled right off and you could simply drill a hole elsewhere or affix a metered tube as an oil sprayer to the lower gear.

But thinking more, I also suppose the spray to the lower gear could be reduced or perhaps eliminated....the distributor is no longer used/needed with a crank trigger....the oil pump no longer needs a driven shaft.....and there is no use for a mechanical fuel pump drive. With no soft brass gear being utilized, the normal 'splash' lubrication from the engine would probably suffice for the lower chain drive. For example, the upper gear does fine without pressurized lube, right?

Bob

 

[RallyBob]

then again lets say you did do every thing that could be done to a Race Head wouldn't the 45 mm Carbs get in the way

Dave, the carbs are definitely the weak link. Or should I say the choke diameters. I suspect FI will make a huge difference, since the TB's will have no chokes....45 mm straight through. You can't do that with carbs. With no chokes, there's not enough signal to pull fuel from the mains. 40 mm is the largest available off the shelf from Weber. In dyno testing, machining a set of custom chokes to 41 mm gained 6 hp. That's a TON of power, so I imagine the 45 mm TB's will help a bunch. Just my opinion.

Bob L.

 

[RallyBob]

Not to open up a can of worms, but having a set of small venturis on a V8 with a shared plenum is vastly different than the same thing on a 4-cylinder with individual runners. This is the primary reason the SCCA does not allow anything other than individual runner intake manifolds for GT-4.

Even with fuel injected V8 with a common plenum, it needs a far smaller throttle body than a 4-cylinder with a common plenum and single throttle body, even to make the same power.

Bob

 

[RallyBob]

I here 197hp is the Max GT4 motor

I wouldn't say max, since that engine was far from optimized. The owner prefers durability over max power, hence the 197 hp rating. I know of at least a half dozen areas that could be drastically improved to gain power. But the current engine also is good for 2 full seasons between rebuilds. There is no other competitive GT4 engine that can go half that distance between rebuilds.

Rod ratio can be improved, the crank could be lightened, the rod journals turned down to reduce friction, more windage reduction, smaller stem valves, hotter cam, tricker intakes and a better header could be built. Still room for more, I'd say another 12-15 with dyno work and the same basic head/shortblock combo.

Bob