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Sorry, didn't mean to scare you, just wanted to give you a heads up on making sure you have a data logger that will warn you of knock counts. My logger wasn't working correctly while I was running the car and paid for it. Looking back, I also didn't mean to high jack your thread. I'm going to start a new one regarding spark plug choice for the people running the Dr750's. Good luck on the build and I'm excited to see what kind of numbers you put down!
 

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Discussion Starter #45
Sorry, didn't mean to scare you, just wanted to give you a heads up on making sure you have a data logger that will warn you of knock counts. My logger wasn't working correctly while I was running the car and paid for it. Looking back, I also didn't mean to high jack your thread. I'm going to start a new one regarding spark plug choice for the people running the Dr750's. Good luck on the build and I'm excited to see what kind of numbers you put down!
No problema, you did not high jack my thread, I dont take it as my thread, just one more dr750 thread... please dont stop writing, we are all learnig from all...

Which logger you have that stop running? And how may knock counts did you have (like normal), from 0-5 or more...?
 
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I used ww fluid when I first started messing with meth injection. It's water content is really high. Offsetting it with heet deicer only makes your cost closer if not more than just buying meth straight. I'm not interested in paying for water. I buy meth in 5 gallon containers and it's usually between $40 and $50 with tax. Some claim they can find it cheaper. 1 gallon of ww fluid iirc is $3-$5. Each bottle of heet is another $2-$3 iirc. Once you get enough heet in the mix to get to or near a 50/50 mix, you've spent what it costs to buy meth straight. At that point, buy it straight and make your own mix from the tap (filtered).

Spark plugs should be a moot point with the cost of those NGK's. Why risk it by going hotter? Go with 8's. They will not have any hotspot issues at your modest power level and at their price point, just replace them every time you pull the intake.
 

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One fix at a time
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Racing at Seekonk, I'm only racing in 1st and 2nd, but when I hit the track, I'm rowing through gears. 10's seem like a bit overkill and I heard you wont get much life out of them due to them fouling up quicker. I wish I could find that conversation Ray stated on Facebook regarding plugs for his DR750 setup.
Ray states he runs #10 plugs. I know it sounds crazy and super cold but he does 1-5 full pulls and even with #8 and 9 plugs he still got some pre-ignition at the end of 4th. So much heat gets built up on those long multi-gear pulls. That's probably why I haven't had any serious issues. Most I may do is 2-4 up to about 130-140mph and that was when I was lifting the heads. Check out Ray's thread here or search it in the 3SGTO group. It's easy to find his setup.


SO what do you suggest for pump+meth, which spurk plug. I wont race the car, just some pulls on highway.

What are simptoms of pre ignition?
I would probably do 8s since I doubt you are going to be running crazy boost 30+ psi. There's a big difference between 22-24 psi on pump + meth and 30+ on E-85 or race + meth. The DR-750s won't last forever above 30 psi anyways. I can think of at least 5-6 people with them that have sunk $5-9k into DR-750 turbos because of rebuilds due to failures and pushing them to the limit. No thanks.

You really don't know pre-ignition when it happens. There aren't any symptoms before it trashes your pistons. A forged lower end you may get a little luckier but if you don't get out of the pull you'll smash the center mains, spin a bearing, and possibly bend a rod too. It won't show up as knock on E-85. I have no experience on race gas or pump + meth. I do know that E-85 is more prone to pre-ignition than some of the other fuels so you just have to cover yourself by running a cold enough plug. I'm going to switch to 9 or 10s just because it's $16 a set compared to $6-7k for a rebuilt forged motor and rebuilt large TD04s. Not worth it.


Ok guys what do you think, DLI or cheap hotwire coils? Some says that hotwire coils is enough for DR750, but other prefere HKS DLI.... of course there are some stories for HKS DLI problems too...
Either one works. There are some guys running 30 psi on hotwired coils. You will wear them out faster but there is no data on how much quicker they'll wear out. I'm sure a DLI will wear them out quicker too. Just expect every 2-3 years you'll need to refresh the whole ignition system with new components if you drive the car a lot. You have to pay to play.
 

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Discussion Starter #50
Well now I have Denso Iridium IK24, that is like #8 cold plug. I dont know what gap I have, because my mechanick told me not to gap Iridium plugs. But I have spark blow out if I go to red line...

Should I go to #9 or #10 plugs? Why dont we use multi spark plugs?
 

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I really dont know where to buy DLI...3SX have them but 600$, it is little to much, because we know they were around 400$....maybe I will try hotwire first. I also saw that Ninja Performance have coil htwire kit. How is doing business with Ninja? I have never dealth with that company, but look like this store have some nice items.
 

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Ray states he runs #10 plugs. I know it sounds crazy and super cold but he does 1-5 full pulls and even with #8 and 9 plugs he still got some pre-ignition at the end of 4th. So much heat gets built up on those long multi-gear pulls. That's probably why I haven't had any serious issues. Most I may do is 2-4 up to about 130-140mph and that was when I was lifting the heads. Check out Ray's thread here or search it in the 3SGTO group. It's easy to find his setup.




I would probably do 8s since I doubt you are going to be running crazy boost 30+ psi. There's a big difference between 22-24 psi on pump + meth and 30+ on E-85 or race + meth. The DR-750s won't last forever above 30 psi anyways. I can think of at least 5-6 people with them that have sunk $5-9k into DR-750 turbos because of rebuilds due to failures and pushing them to the limit. No thanks.

You really don't know pre-ignition when it happens. There aren't any symptoms before it trashes your pistons. A forged lower end you may get a little luckier but if you don't get out of the pull you'll smash the center mains, spin a bearing, and possibly bend a rod too. It won't show up as knock on E-85. I have no experience on race gas or pump + meth. I do know that E-85 is more prone to pre-ignition than some of the other fuels so you just have to cover yourself by running a cold enough plug. I'm going to switch to 9 or 10s just because it's $16 a set compared to $6-7k for a rebuilt forged motor and rebuilt large TD04s. Not worth it.




Either one works. There are some guys running 30 psi on hotwired coils. You will wear them out faster but there is no data on how much quicker they'll wear out. I'm sure a DLI will wear them out quicker too. Just expect every 2-3 years you'll need to refresh the whole ignition system with new components if you drive the car a lot. You have to pay to play.
I like when TurboSinceBirth posts. Always alot of great info.

:beer:

I just got the copper 7's for my new 19T-HL's. Gapped them to 0.030. Kinda regret not getting 8's after reading this.

Also working on a direct port meth system right now.
 

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Well now I have Denso Iridium IK24, that is like #8 cold plug. I dont know what gap I have, because my mechanick told me not to gap Iridium plugs. But I have spark blow out if I go to red line...

Should I go to #9 or #10 plugs? Why dont we use multi spark plugs?
I have once Iridium plug and i was not happy with them multible plug fails.

I remember that Matt Monet said here forum once "Stay away any iridium plugs"

Now i drive 8 +22-25psi (no problems at all) sometomise knock between 5-8 but no big deal. Later summer i am gonna try 9 if knock goes away.

I recommeded that you put ngk 8 plugs
 

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good memory....foud it :)


There are 3 plugs I would recommend

1 heat range cold

the BCPR7ES, this is a good all around plug, long life and not Expensive
Another very good choice is to go with a NGK R5671A-7 This plug is a non-resister plug so it will be less spark blow out prone then the Resistor BCPR7ES is.

2 Heat range cold

R5671A-8 , This plug is also a non resistor plug and will pull more heat from the chamber. But will foul easier because it's a 8 heat range.


But most importantly get a HKS twin power DLI. This will allow a larger plug gap, better idle, and say byby to spark blow out.


And STAY AWAY FROM ANYTHING iridium! I can not stress that enough.

My DR-750 car had the same set of BCPR7ES's in it for over 2 yrs going back to when the car had 16T's on it. I have a HKS DLI, and was running a 0.030" gap. I ran the boost 20+psi that entire time (and up to 32psi). I just started getting a little blow out a few weeks ago when running over 30psi, I pulled the plugs and thy had so many miles on them that the gap had eroded to over .036", so I went ahead and replaced them with a set of the non-resistor's.
 

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Marshall Taylor
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I really dont know where to buy DLI...3SX have them but 600$, it is little to much, because we know they were around 400$....maybe I will try hotwire first. I also saw that Ninja Performance have coil htwire kit. How is doing business with Ninja? I have never dealth with that company, but look like this store have some nice items.
Chris (Ninja) has always delivered the goods to my knowledge. If you order from Ninja expect several weeks before the item(s) ship. Chris has been battling cancer for a number of years.

Good luck,

Marshall
 

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You'll be fine with the iridium plugs. Gapping them just requires more care to not break the electrode off. The 8 heat range and your modest power goals will give your engine long life maintenance free. That's the advantage of iridium. It doesn't break down like copper.

You can probably get away with .032"-.030" gap for that power level. I can go to 700 wheel with .028" gap and dli.
 

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Keep in mind that Ray has to run colder plugs specifically because of two factors, E-85 and also higher cylinder pressure in lower rpms due to the low end torque 750+AWTQ at 4k rpms that the DR-750s make. Those in combination with high amounts of heat build up in long 1-5 gear pulls can cause some serious pre-ignition events that blow up a motor. It's not detonation(knock) but rather the fuel igniting too soon more than likely due to heat spots in the combustion chamber i.e. a glowing plug tip because it can't dissipate the heat to the combustion chamber or transfer it to the head.

Ethanol burns faster than gasoline. Because it has a quicker laminar flame speed, overall it requires less ignition timing than gasoline. However, due to its higher knock index(more resistance to knock) than gasoline, you can run more advanced timing for more power than pump gas because it is always knock limited. The draw back is that ethanol prevents knock so well that you can advance the timing past MBT, it won't knock, and when you keep going the motor ends up bending rods or spinning bearings quicker than you can realize it. That's why you have to tune timing on a dyno that lets you load up the car and watch for when the torque starts dropping off so you can back it off a couple degrees to keep it safe.

I would have to go back in the thread but I assume you won't be running ethanol is slovenia and probably pump + meth. In that case, you're not going to have as much issues with pre-ignition. That's something that is more specific to ethanol and it's characteristics. A #8 plug is probably fine in that case and no need to run a #10. Also, for ethanol and higher boost(30+) a non-projected tip non-resistor plug is very helpful. It's all about heat management and getting rid of that hot electrode that can causes issues. For pump + meth you won't be stressing everything as far. Kywhitelightning also was running race gas + meth over 30 psi of boost and #8s worked just fine for him.

Maybe some more experienced pump + meth users will chime in since mine is strictly based on E-85 the past decade. Eventually I will have to run pump + 100% meth and hope to not ever need to run race gas but we'll see.
 

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Alcohols based fuels such as E85 are more prone to pre-ignition due to their thinner flame walls in comparison to aromatics and gasoline. What this means is the energy cost to auto-ignite the gas charge will be less, as well as size/radius needed of the 'hot spot' found on say a spark-plug tip, exhaust valve, particles from oil or contamination etc to trigger auto-ignition.

There have been a few white papers on this.


Since you cannot change the characteristics of the fuel, you have to pay attention to that pre-ignition is temperature/pressure sensitive and a major contributor to the on-set of pre-ignition is exhaust gas temperatures which we can have some control off...

Running less rich = higher EGT
Running less timing = higher EGT
More exhaust back pressure = higher EGT
More power / duration at WOT = higher EGT
 
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