Advanced Engine Theory and Design
- Thread starter Alky V6
- Start date
Lets discuss spark plugs.
Different designs and which are working out the best.
Availability of racing designs.
Tuning using spark plug readings.
I'll start out with what I'm using and what I would like to use just to try them out.
I'm currently using a regular nose NGK, part number R5671A-9. It is a middle of the road heat range for that series (7-11). The 9 in the part number designates the heat range. It comes with a ground electrode that extends across the whole center electrode. I modify (cut back) the ground electrode so that the sharp edge of the end of the ground strap forms a side gap to the center electrode. Gap is set at .022". The main reason for cutting back the electrode is to keep it from overheating and causing a preignition condition. This is a standard modification for any plug that will be used in a nitrous application. The less ground strap you have hanging out in the combustion chamber to catch heat, the less chance of it becoming red hot and igniting the fuel mixture prematurely. Ever since I started cutting back the ground strap I noticed the heat discolorization to the end of the strap has been much, much less and in most cases nonexistent. I should tell you about the experience that taught me to cut back the ground strap. Next post.
Different designs and which are working out the best.
Availability of racing designs.
Tuning using spark plug readings.
I'll start out with what I'm using and what I would like to use just to try them out.
I'm currently using a regular nose NGK, part number R5671A-9. It is a middle of the road heat range for that series (7-11). The 9 in the part number designates the heat range. It comes with a ground electrode that extends across the whole center electrode. I modify (cut back) the ground electrode so that the sharp edge of the end of the ground strap forms a side gap to the center electrode. Gap is set at .022". The main reason for cutting back the electrode is to keep it from overheating and causing a preignition condition. This is a standard modification for any plug that will be used in a nitrous application. The less ground strap you have hanging out in the combustion chamber to catch heat, the less chance of it becoming red hot and igniting the fuel mixture prematurely. Ever since I started cutting back the ground strap I noticed the heat discolorization to the end of the strap has been much, much less and in most cases nonexistent. I should tell you about the experience that taught me to cut back the ground strap. Next post.
Cutting back the ground electrode is nothing new. I used to cut back the ground strap halfway in high school in the early 70s. And it was being done by others way before that. The reason for doing it back then was different in my case. Electricity will jump from a sharp edge easier than it will from a rounded edge. Less chance of misfire. It was one of my little tuning procedures I used that made that little 307 SBC surprise a lot of people. Back to the present. I started out by cutting back the ground strap halfway with the Alky V6s. Cutting back a ground strap halfway means having to end of the strap extend halfway over the center electrode. With version 2.0 I did notice some heat discoloring of the ground strap end (1/8 inch), but I didn't feel it was something to worry about. Version 2 was the engine I started using nitrous injection to quickly spool the turbo. I use a 200 HP shot (jet size), but when using alcohol, the actual HP level increase is more like 140-160. Before using nitrous for turbo spooling, I had only read about it in books. It made good sense to me and I always wondered why it wasn't done more than it is. I have to tell you after doing it, it is the cat's meow. :wink: At a later point in the testing of Ver. 2 I decided to try injecting the nitrous for the complete run. When I look back on it and think of the tuneup configuration (mainly the equipment, not the engine software) I was using at the time, it was a foolish move. For one thing the wastegate was way too small to handle the extra exhaust energy that would be present for the whole run. I have since installed a 60mm wategate, but I would also install a turbine housing with a larger a/r and 2 steps colder spark plugs. I did make the run and man was it pulling. 
Shortly after shifting to 2nd, there was a loud intake backfire (pop) and I got out of it. The wastegate could not handle the extra exhaust volume and the engine overboosted. The engine came out of it OK, except for the spark plugs. Two were missing all or part of the porcelain and the rest had the ends of the ground electrodes partially melted back into a ball. I think I still have one. I'll try to remember to post a pic of it. A leakdown test confirmed the engine was OK. I noticed how far back the electrode melted and that is the point where I now cut back the electrode to.
Shattered porcelain is a sure sign of preignition. I was lucky on that run. I have since only used the nitrous to spool the turbo.
I am using a regular nose plug (non-projected tip). It has a shorter ground strap and when cut back, it is really short. The shorter the better.
One plug type I keep wondering about is the retracted gap or surface discharge. Does anyone have any experience using these plugs?
Shortly after shifting to 2nd, there was a loud intake backfire (pop) and I got out of it. The wastegate could not handle the extra exhaust volume and the engine overboosted. The engine came out of it OK, except for the spark plugs. Two were missing all or part of the porcelain and the rest had the ends of the ground electrodes partially melted back into a ball. I think I still have one. I'll try to remember to post a pic of it. A leakdown test confirmed the engine was OK. I noticed how far back the electrode melted and that is the point where I now cut back the electrode to.Shattered porcelain is a sure sign of preignition. I was lucky on that run. I have since only used the nitrous to spool the turbo.
I am using a regular nose plug (non-projected tip). It has a shorter ground strap and when cut back, it is really short. The shorter the better.
One plug type I keep wondering about is the retracted gap or surface discharge. Does anyone have any experience using these plugs?
I know this isn't an engine subject, but we might get some interesting views on this one.
For doorslammers the common thinking is to put the battery in the trunk and over to the right side of the trunk. This takes weight from the front end and adds the weight over the rear axle to help weight transfer and traction. I have heard people say that the right rear tire has a harder time acheiving good traction so that's why the battery is installed over the right rear tire. I have a real hard time picturing in my mind why the battery needs to be over the right tire. Does anyone have any good reasons for this long standing procedure?
For doorslammers the common thinking is to put the battery in the trunk and over to the right side of the trunk. This takes weight from the front end and adds the weight over the rear axle to help weight transfer and traction. I have heard people say that the right rear tire has a harder time acheiving good traction so that's why the battery is installed over the right rear tire. I have a real hard time picturing in my mind why the battery needs to be over the right tire. Does anyone have any good reasons for this long standing procedure?
well as i grew up in the 60s and 70s and it was common knowledge that the torque reaction twistied the car to the drivers side so the battery was put there on the right to help keep the car from twisting just as there were air bags installed with more pressure in the left bag
With engines that rotate clockwise (viewed from the front), the car twists up on the drivers side and down on the passenger side. We increase air bag pressure on the right rear to help level the car out at launch. What do you think Robby?robbyc said:
now that i think about it i dont either maybe they were dislexic too haha.... but if anything it should be over the left to help even out the rear of the car when you launch it would be interesting to see if you put the batt on the left side to see if it took a differnt bag pressure to even out launch what do you think don?
Don, how about taking a virgin stage 2, on-center block and angle boring the cylinders toward the power stroke , freeing up power,and creating a virtual longer rod ratio only on the power stroke. You could probably get more angle than would be needed with a virgin block. I'd bet that just .050 at the top and bottom would be plenty and would produce a stronger engine than one that was straight bored.. This is a proven machining technic to free up power :wink: it can also be used as a tuning method. JEFF
:wink: it can also be used as a tuning method. JEFFDonWG said:
And to futher enhance it, the piston skirts can be drilled 4 holes per side,just under the oil ring boss,on the exh and int. side, to lighten them , and of course rebalance them, because there will be less side force on them, .A lighter piston engine will accellarate faster, all other things being equal. JEFF
With the bores set at an angle to the decks, I can see a problem with the squish band on one bank. You would have to give up any tight deck clearances.
That brings up another question. How important have you all found it to have a tight deck clearance with the turbocharged Buick V6? There is a school of thought that states a tight deck clearance and high cylinder pressures during compression can cause the squish band to somewhat hydraulic.
That brings up another question. How important have you all found it to have a tight deck clearance with the turbocharged Buick V6? There is a school of thought that states a tight deck clearance and high cylinder pressures during compression can cause the squish band to somewhat hydraulic.
Knock
I would really like to see someone develope a race engine knock system, maybe have small sensors on or near each spark plug[ actually use the plug as part of the system ] so knock could be determined at each cylinder. With todays ecm's , being able to individually tune each cylinders fuel and timing, plus intakes could be tuned for maximum and equalized airflow. It seems very obvious the gains that tuners could attain , a knock system like this would be worth its weight in gold. Anybody want one of these, I've got 5 of them ready to ship..............just kiddin :wink: .....somebody develope this and thousands of them would sell instantly. :biggrin: :biggrin: :biggrin: ...........JEFF
I would really like to see someone develope a race engine knock system, maybe have small sensors on or near each spark plug[ actually use the plug as part of the system ] so knock could be determined at each cylinder. With todays ecm's , being able to individually tune each cylinders fuel and timing, plus intakes could be tuned for maximum and equalized airflow. It seems very obvious the gains that tuners could attain , a knock system like this would be worth its weight in gold. Anybody want one of these, I've got 5 of them ready to ship..............just kiddin :wink: .....somebody develope this and thousands of them would sell instantly. :biggrin: :biggrin: :biggrin: ...........JEFF
Don, couldn't you take an angled cut across the piston crown to match the bore angle to keep the squish gap constant around the piston? The "coming" knock detection system puts a small test current through the plug gap after the cylinder has fired and measures the residual ionization level to determine if knock occurred. I know Saab is working on this (along with others, I'm sure) but I don't think anyone is ready for production.
J@S had the knock aleart out many years ago. It measures the time when the knock occured to which cyl is being fired, Then it knows which cyl was knocking, and only retards that cylinder. You can still buy it today for about $500, and units are custome made to each type of igntion system.
