[TGSI Racing]

As many of you know, I am in the process of developing a GT-4 race engine to take a run at the SCCA championship. I am trying to make more reliable HP than any one else (including Rally Bob) has ever made in an SCCA legal GT-4 engine... that's a tall order.

Along with this I am writing a series of small articles on a performance engine build using the GT-4 engine as a basis. There is/will be information in the series for everyone building anything from a "grocery getter" to full tilt race engines... ok, maybe not much for the grocery getter.

I have contacted Gary and he has said that it is OK to use this forum for asking questions. You can email me directly, but I would prefer to answer questions here so everyone can benifit from the question. Other inputs are welcome too, but let's not diverge this section too much from the performance engine build up.

The first of the articles... starting with the short block are posted on my web site: www.tgsi.com When you get there, click into "Opel Tech Topics"

 

[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

 

[TGSI Racing]

BOB!!!! I'm glad to coax you are back. I'll be looking for your input when I say... or do something... that's going to "hurt" me.

 

[ConreroGT]

woo hoo!!!

I'm very excited about these write ups and information. Even at a lower level I want to make available all the stuff I'm doing to my engine....once I have it installed and running. Like I said before..I'm building my engine as a "research" project. More hobby/fun then anything. I want to have a web page with detailed specs on the car and what I'm doing...everything from carb jets to cam size to timing etc...

So I'm really looking forward to hear from both Westcoast Bob and Eastcoast Bob.

thanks for the future info guys....

 

[RallyBob]

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

 

[Paul]

Bob D.

Thanks for taking the time and effort to share this project with us. What kind of information can you provide in the way of oil passage way chamfering (rods and crank) and timing cover to timing cover gasket to block blue printing.

Thanks again.
Paul

 

[TGSI Racing]

Rally Bob asked about a dry sump. Well, the quick answer is yes... but it's not that simple. I have never had any oil problems with a stock oil pan modified with baffels/"trap doors", a windage tray, and an accusump. However, a good dry sump system will actually pull a vacuume in the crankcase which will lower windage... thus a little more HP. So far, I am using my F-Production car as a test "mule" for the engine. I won't go to a dry sump until (if) I build the tube frame car.

The problem with the dry sump is finding a way to do it. I have not worked on figuring out how to do it. The problem is how to replace/bypass/block off the stock oil pump. So, Rally Bob... any input you can give here will be greatly welcomed.

Paul asked about chamfering the crank. The next segment in the series is crank prep and I'll cover that in there. As far as the front engine (timing) cover goes... There is no real magic here. Just make sure the gasket surfaces are cleaned well. Then the trick that I use is I soak the FelPro timing case cover gaskets in oil for at least 1 hour. The gaskets will soak up some oil and when you torque the cover on, you'll see some oil squish out. Using this method, I have never had any leaks from the front cover. By the way, I never use any "goop" on any gasket and only use FelPro gaskets.

 

[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.

 

[Paul]

Bob (Rally Bob),

Very Impressive. I do have a novice question, tho. Can you give a description of the oil flow path. 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.

Thanks again for the great info!
Paul


PS Never Mind, Bob L., I figured it out!

Thanks Anyway
Paul

 

[Paul]

Bob Dennard,

I have a question about align boring the Main Bearings.... After this operation is performed, are different size bearings required? Meaning, are bearings with a larger OD required? If so, where does one purchase such an animal?

Thanks
Paul

 

[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

 

[jimsky]

Bob, excellent explanation. Without diverting this thread, could I ask for you to comment on anything special I should be aware of adding a remote oil filter adaptor and cooler? Thanks.

 

[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

 

[TGSI Racing]

Rally Bob... Really Good Stuff! The best solutions are usually the simple ones. So I think that the easiest way to do this is to run the "pressure" feed in from the external pump (cooler etc.) into the center of the oil filter boss like you have done. I would also put a block off plate over the oil pick-up holes in the block. (I'm not sure the block off plate is necessary, but it seems like I should)

Paul.
During the process of "align boreing" the main bearing bosses, the inside diameters are "re-sized" to be exactly original specification. This is done by machining a little bit of material from the bearing cap mating faces... thus making the inside diameter too small. Then when the bosses are bored out, they are restored to their original size. So, that's a long way to say that there are no special bearings needed.

Jimsky.

There will be some oil pressure drop with an external cooler. So you need to do a couple of things. First, you need to increase the pressure output of the oil pump. This can be done by increasing the tension on the oil pressure relief valve spring. Second, if you are using an aftermarket external oil filter adapter(to get the oil out and back into the engine) you need to block off the oil filter bypass valve (the little ball in the oil filter housing). (The increased oil pressure will cause the ball to open and bypass the external filter/cooler.) Rally Bob has shown an excellent way to do this by by taping the hole and plugging it. In fact, Rally Bob has shown an excellent way to eliminate the need for a external oil filter adapter. The biggest problem with an aftermarket adapter is that it is difficult to cleanly route the hoses to/from it without chaffing. Rally Bobs solution eliminates that problem.

 

[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

 

[TGSI Racing]

I have put the next "installment"... crank prep up on my web site. Go to the site and click on Opel Tech Topics and then click into the section you want. As usual, post any questions here

The web site is
http://www.tgsi.com

 

[ConreroGT]

Nice installement Bob. Very helpful info the way you breakdown what should be done between "grocery getter" and "full race"