ZC and aerodynamics

Posted by T.O.O. on April 28, 1998 at 20:46:40:

Good to hear from you. The ZC is my current favorite powerplant for my '89 Civic. It may not be the best Honda engine from a geometric standpoint, but they can provide serious power and fun when properly "built" and in the proper car.
You're making the traction control system far more complex than it really is, and as we're currently doing a search for patent, I can't really say more. It took a complete outsider to FWD about 5 minutes to look at the traction situation, and then make us all feel stupid as hell. By the way, he's our chassis expert, and master fabricator. His cars have won the NHRA Pro Stock championship for the last 8 years. Only the desire to work on some "special" projects, where we could work one on one with no outside interference caused him to "move".
The ZC kits are already a done deal. We've got almost two years testing on those engines, and I'm sure we can work something out for you to "test". We are, however, in the middle of some critical agreements regarding production rights on the plastic components, and it will be a week or two before everyone is happy, and then I can help you out. Make sure you install a Quaife first.
I only have my Civic dropped about 1.5", due to the condition of the roads here, and I've never been able to generate the cornering grip necessary when the car has been lowered more...regardless of attempts and suspension tuning. You might notice that even the Mugen suspended Type R's are not lowered more than .5" from their stock height.....it's the weight transfer, and you can not get it if the car's too low because the suspension won't work enough to allow it.
The 3" collector begins in front of the engine (the primary tubes are very short) and as it bends under the pan it is "D" shaped with the flat of the "D" on the inside radius. After the turn the tube is oval shaped before it goes round again prior to the 3" cat. The system is 3" round from the cat. to the exit which is made of a 14" long piece of 3" id. pvc tubing with "dimples" it's entire length. As it's simply painted a dull silver, it's 3"+ od. doesn't attract much attention....Chrome tips don't add power. Since the pvc tubing is acoustically inert, when you throw in some properly spaced "dimples", the sound is dramatically reduced, and the police never hear or look at my beloved Civic.
Cowl induction is a great way to intake outside air of ambient temperature. There is a high pressure area at the base of the windshield, and you need only turn your "climate control system" to outside and cool to appreciate the amount of pressure available there. I believe that for most normally aspirated cars, it's the optimum place to draw atmospheric "fuel" from. I currently have a 3" diameter hole cut below the right hand parking light that simply allows air to enter the inner fender area with less restriction. We have constructed an air box which resides to the right of the battery, and it has a foam lip which seals to the underside of the hood. At the bottom and side of the air box, there are some holes, 2.75" dia. each to be exact. No attempt whatever was made to seal the inner fender gaps or to achieve "ram", I simply wanted ambient temperatures at positive (as opposed to negative) pressure. In this configuration, I don't sweat deep water, and it's been worth 18 hp in back to back from 45mph up in tests using our Vericom on our test track.
Measuring pressure is relatively simple to do. I prefer to tuft test the car first, using a chase car with a camcorder. You need a wide road so the chase car will not adversely affect the flow over and around the front of the car. Short pieces of yarn taped to the body work great...as long as the color contrasts with the car's color. You'll notice that the area above the bumper is almost "dead", however, the area under is very active. The area on top of the hood from the middle of the hood to the headlights is "dead" as well.
Now that you have some notion of where the air is active, determining pressure is simple. Assuming you do not have assess to manometers, buy a piece of plywood and cut it so it's 2' high and 2' long. Cut some wooden yard sticks down to 2', and use some "Hot Stuff" to attach 3 or 4 to the board in an evenly spaced vertical orientation. Buy about 20' of clear tubing and attach "U" shaped segments to the board using "U" shaped brads. Do not crush the tubing, and place it so the yard stick is between the legs of the "U" tubing. Do the same with the other 3. You now have 4 manometers or "U" tubes.place the board in the interior of the car where it may be observed or taped. Fill each tube with water with a dash of red food coloring and a drop of soap to cut surface tension. when filling the tubes , fill them until the water level is at 12" on each leg of each tube. This is "0" pressure. Slip a short tube in one end of each "U" tube. Then slip a piece of clear tubing over the connector tube, and run it all the way to the area where you want to measure pressure. Tape the tubing to the body where ever necessary. If you want pressure at the front, aim the end of the tube forward, using your tuft test results to determine "forward" and duct tape the tube so it is aimed squarely at the on coming air. Place other tubes from the other manometers where ever you want to test pressure. Run the car up to various speeds and tape the amount of movement observed on each "U" tube, make sure that you accurately record the speed while recording the movement of water in the tubes, and make sure you run all the way to the top speed you feel is the maximum you'll be seeing in a race or what ever. Having someone call out the speeds and getting that on the tape is a good move.
The water column in each tube will have moved during this test, unless the pressure in the car is the same as where you tested on the exterior. What does it mean? The water in the test leg of the "U" will go down and the other side will rise if you are seeing positive pressure, the lower it goes and the higher on the pooosite side, the greater the pressure, and conversely, should the column rise, you're in a low or negative pressure zone, and you won't want to attempt to draw air there....it could actually attempt to suck air out of your intake. I realize this may sound primative, but we did it a Penske's and we've done tests like this hundreds of times in many cars. On small cars where budget allows we simply place pressure transducers that are wired to the data recorder. When Bill Elliott run over 200 at Daytona, and 209 at Talledega...finally 213mph., everyone thought it was the engine, and it was. However, as we had no tunnel time prior to Daytona, we did what I've just described, and we found that at 197mph. the pressure in the duct at the base of the windshield went away and became a vacume. Some reworking of that entire area allowed us to see positive pressure past 220mph, and the rest is another story for another time, but it's attention to details throughout the "package" that generally make my combinations work, and my work doesn't come cheap, especially in todays "win at any price" pace.
My hours....that's a good one. What ever it takes. Not simply to please a customer, but it has to please me, and my standards are much higher than my customers. It's typical for me to bring a head / manifold / piston, etc. home and I have a specially constructed "nignt stand" to set it on, so I can study it while reading, and typically it'll be the last thing I see prior to sleep and the first when I wake up, and, yes, Susanne hates my work.
Post a mailing address (temp. will work) and I'll send you some data. BTW, where did you get your ZC adjustable cam pulleys, and have you ever simply used the SOHC distributor and eliminated the secondary TDC sensor?
Look forward to hearing from you............T.O.O. .................

Re: all motor ZC

Posted by T.O.O. on April 29, 1998 at 21:00:41:

You have no idea how many "well sponsored " cars have used that pressure system....I think one of the first times I used it was in one of Penske's Camaros that Mark drove, and we had to visually record the data, which made for some rather exciting rides for your's truely.
I think that anyone who spends some outrageous price for a name is stupid. As I've said before, engines don't know what name's on the valve cover, and if they did, it wouldn't affect their performance one bit. If you don't run a minimum 2.5" cat and system, you'll get lots of boost, but you'll lose a lot of power. Restriction on the exhaust side is more important with a blower than a turbo, but too much will drive boost #'s up and performance down because the engine can't get rid of the exhaust fast enough. The intake charge stacks up, and you can impress the hell out of people with the boost #'s you get, but the performance will suffer.
Everyone said I was crazy when I went from 2.5" to 3", but all that stopped real fast when they saw the acceleration curves....dramatic difference.
Just for the exercise assume you have 350 hp with your Honda. Now look at some guys Camaro that makes the same power. As the exhaust system on all late models is one key to their power, measure the tube diameters on the Camaro, calculate the combined area, then figure what single tube size will provide the same area.
On the Z C engines to be honest, I never ran one normally aspirated, but my observations relative to relationships I've found work over the years are: The ports are generous, both sides. I'd never use larger valves due to shrouding. I'd configure the valve seats to curtail flow at low valve lifts, so there won't be as much reversion and backwards flow at overlap. The primary pipes on the header need to be swedged larger and maintain their round shape at the flange intersect (so there will be a gross mismatch at the top and bottom). The head should have the "quench" area welded up on the intake side, so it'll be flat with the deck, or take the easy way and mill the "quench" to the same depth in each chamber, and install pistons which have a raised "quench" on the intake side. The deck clearance on the intake side should be + .20", that's .020" out of the hole. The head should have the bowls blended to the seats, and any dingleberries removed. Do not polish or clean up the port in any way, the cross section and volumes are far to large stock. The only reason these engines aren't totally useless for the street is the short rod length and resultant high piston speed. The higher the piston speed, the higher the over all pressure drop across the valve and since this will increase velocities, the engine will think the ports are smaller, and you'll have "some" torque. The engine should also get a .5mm over bore to aid breathing. The crank is a good piece and should be made "aerodynamic"....not knife-edged. Some light weight Cunningham or Oliver rods would be the ticket, with tool steel pins. As for cam timing, you'll have to let us all know for the n/a engines. All my cams currently stagger the intake valve lift, but that's starting to get into crazy stuff like my 23-1n/a compression ratios. I'd better stop before I lose what credibility I have......remember, I get all this stuff from Popular Mechanics, while tending my students in high school auto shop class, and the rest simply comes to me after I've had a few six packs.
NHRA's in town, and so are many customers...it will enevitably eat some of my time here, and how about an answer to my question regarding using the single distributor with no TDC indicator on the front cam .
...................................T.O.O. ........................................