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You can reuse OEM head bolts (done it many times). Never used ARP bolts, so I have no experience in reusing them. I'm on the 4th or 5th torquing of the same set of OEM turbo bolts. I would check with ARP, and if you can reuse them (i expect that you can), see if you can get one bolt. The other option would be to use a complete set of OEM used or new turbo head bolts. I wouldn't mix and match the ARP with OEM. Pete

Yes you are correct, the LS1 coil draws a bit more max current (charging current). I'm not sure if this really gains you anything as it appears that the spark energy is about the same. The Yukon coil may be a bit more efficient. To show the min discharge time, I set it low in Megatune (0.5mS), so that the Megasquirt would not change the dwell at high RPMs. Then I adjusted the RPM just to show the discharge time on the waveform. If I set the discharge time to 1mS on the Yukon coil and try the same test, the Megasquirt will change the dwell to prevent the coil from getting into a state where it never fully discharges. As far as trying different gaps, there is very little difference with a wider gap (ran up to 0.045). So I am convinced that the optimal charge times are correct above. Running any more dwell than that will just generate heat and reduce the life of the coil. Pete

I think I will re-run my tests with different gaps. The gap I had the BPR6ES set to was 0.034" (I think). What might be happening is that the gap is small enough where the spark jump quicker. So what happens is the coil goes into current limit mode sooner because it has less distance to jump, which means more voltage, and a longer coil charge time (dwell). In my earlier tests I may have had the gap set much wider. I'll re-run the test and post the results. Pete

OK, thanks to BRAAP I have an Yukon coil to mess with. This is the good part. The bad part is I no longer work for a Scope maker, so no more $40k+ scopes to mess with. So I made these measurements with my 200MHz SDS USB scope. I also no longer have a current probe either, so I improvised by measuring voltage across a 1 Ohm resistor in line with the ground lead of the coil (so I didn't have to float the scope). Ohm's Law: I = V/R So here is the setup: - Megasquirt with Extra code to control Dwell. - Channel one of scope looking at control signal from Megasquirt to the coil - Channel two of scope looking across 1 Ohm resistor (current) - 12V power supply providing power to coil - Separate 15V supply powering the Megasquirt - NGK BPR6ES gapped to 34 thousands Measurement #1: determine minimum dwell (charge time) that sully charges coil. Top trace is control, bottom is current going into the coil. Notice how the coil fully charges. LS1: 1.9mS Yukon: 1.6mS Measurement #2: determine minimum coil discharge time. Look at the current trace, you can see that when the coil starts charging, it starts from a non zero value because the coil had not fully discharged from the previous firing. If I increase the RPM more, it will exaggerate the effect. I adjusted the RPM so that it was just on the hairy edge to show the minimum discharge time. LS1: 1.5mS Yukon: 1mS Measurement #3: Effects of increasing dwell beyond minimum. If the charge time is increased more, the coil will go into a mode where the current is limited by rapidly firing the coil on and off. The control module in the coil pack is doing this to prevent damage to the coil. The effect of running more dwell is multiple sparks. Too long a dwell will effect you max rpm depending on how many coils you run. Both the LS1 and Yukon coils do this. In summary: The Yukon coils are a better coil design for many reasons: - Shorter minimum dwell increases RPM potential - Shorter minimum discharge increases RPM potential and allows a longer max dwell to be run. - Physically smaller, and has cool heatsink - Although I could not measure it, the spark energy "sounds" stronger at the plug. I can't confirm this because they both use about the same amount of current (about 2A peak). Now comes the weird part. The LS1 measurements I previously made did not show the current limiting/multiple spark mode that I've seen with in these measurements. Yes, I made the measurements differently, with different equipment, but I still don't understand it. I will try to borrow the same scope I used in my previous measurements. Anyway, I'm going to sleep on it.... Pete

That is what we did with a spare parts and a spare shell we had kicking around. After 7 years of upgrades, tuning, chassis work, it's damn good track car.

Hi Clive, Thanks for the update. What are you doing with the 73'? Dedicated track car? Pete

I got them on Ebay. Don't remember how much but they were cheap because one out of eight had physical damage.

In the case of high speed design (which this isn't), sockets are not acceptable as they introduce too much capacitance. In this case there is no reason besides stupidity. Or, they didn't buy the kit and omitted the socket from the BOM to save money (again, stupidity). Pete

They are just generic parts store Camaro LS1 wires.

Thanks Guys, My old Wolf 3D V3 only does wasted spark, and alternating injection. Using the LS1 coils is actually a bit better than wasted spark where a single coil is shared to fire two plugs. In that configuration, one plug has slightly less spark energy than the other. With a separate coil on each plug you get equal spark energy to each plug. I started just experimenting with mounting them on an old valve cover, but it came out nice, so I decided to paint it up. This is how I mounted them. - Coils are centered on the plug holes in the head. - Holes are 2.25" from the valve cover gasket surface - Spacers are 3/8 aluminum tubing cut to 1" lengths - Bolts are 1/4-20 stainless binder head - A small amount of silicone one each bolt - Loctite I used an 8 pin sealed connector (left over from an RB harness), so all you need to do is unbolt the cover, disconnect the 8 pin plug and plug wires and you can lift the valve cover off. Pete

Thanks Ron! Just finished it today. It was my Presidents Day off project. Was getting tired of looking at the box of LS1 coils and wires. Seems to run great (on jack stands....). Will get it on the dyno sometime this year.

I'm using LS1 coils with my old Wolf 3D v3.0 ECU. The LS1 coils have a hot spark and have the coil drivers built in. They are operating in a wasted spark configuration. There are three 5V ignition outputs used from the Wolf, each one drives two LS1 coils. Kind of looks like a science project, but I like it. Pete

Beause I didn't know if the AEM unit I have is the same as refered to in Megatune. So to be safe, I use generic linear sensor. Yes, the output from the AEM gauge is linear. Pete

The Innovate wideband is almost the same price, but does not include a gauge.

Glad I could be of help Derek. Sounds like your moving the right direction.

The sound is amazing.... Your required fuel should be set around 11 if I remember correctly. You are using 280 cc/min injectors, right?. Start by adjusting the VE table. You tuned it before the TBs, right? Pete

What radiator are you running? What do you estimate your WHP to be?

Sounds about right.

Are you sure? I believe 5th is 1:1 and 6th is 0.7something:1 I almost never hit 5th in my track car. At 1:1 with a 3.9 I'm doing around 120MPH at 6500RPM. Only on really long straights to I get it into 5th.

The VQ has a nice flat torque curve, so the 3:54 might be good. All I know is my NA L28 track car would be a total dog with a 3.54 in it. I'm sure it has to do with the 81ZX vs 350Z trans ratios too. I'm running a R200 3.9 CLSD in there now, and have run a R190 4.44 LSD in it (until the pinion seal let go). If I can get the parts for the R190 I'm going to give that ratio another shot. Of course your VQ has at 50ft-lbs and 50 more hp than the L28 in my track car. That helps for sure. Pete

Sweet. Nice work as usual Derek. Waiting with anticipation..... Pete

Great to here that it performed well on the track. Not a big surprise that it ran flawlessly (Nissan engineering). 3.54s in an NA is really going to hurt your lap times. I'd be looking for a 3.9 or 4.11. The cheap OBX LSDs actually work reasonably well for the money. I've got one in my turbo car. Pete

Very nice!

How does it behave without the boost controller removed? Does the boost go to 7psi and stay there? If so, your Home Depot boost controller is probably suspect.

I would also run the power through the shield as well. Otherwise you are putting a big antenna on you 5V logic supply. This will pick up all sorts of engine room noise an potentially put it on the 5V supply inside the MS. This is why all factory TPS wiring shields the TPS signal and the TPS reference voltage inside the braided ground. Pete