Coil Question
 

Hey i was wondering if there are any suitable replacements for the bosch coils that come with the microtech system. I blew one out, and would like to try a different kind.

you can probably just use MSD coils. maybe something like this http://www.amazon.com/MSD-Ignition-8.../dp/B000COUP18

or http://www.atlanticspeed.com/product...idcategory=119

Those will probably work fine. Lots of people use the Blaster SS coils and they are cheap

I'm using two FC3S trailing coils with the ignitors removed to allow them to function with the microtech and x4 box. Its a simple modification, widely done and pretty reliable from what I've seen!

same here t2 coils

The stock coils are said to be better than the bosch

I am using IGN-1a race coils with my lt10s, I deleted the x4 box

not sure if I can post link from another forum, if a problem mods can delete the post

http://www.efi101.com/forum/viewtopic.php?t=6269

So to simplify the situation, I can purchase Blaster SS coils, and hook them up to my mircotech box, and eveything will be okay? I see people talking about boxes and everything, and i just want to have a reliable spark. I'm only runing 15psi, and it breaks up randomly around .7 bar.

What kind of dwell time should i be using on these new coils?

Oh, and if i use the stock FC3S trailing coils, what "modification" needs to be done? Cuase i'm 95% sure i have a few coils laying around!

Sorry to highjack your thread but what about running aftermarket coils with a LT8S that is setup to run stock coils? I guess that you have to keep the stock ignitors to fire the aftermarket coils if you dont have a x4 box.Is that possible?

Extreme rotary, as long as they are direct fire coils with no built in ignitors the x4 box will work with them just fine. And really thats the answer to your second question too! If your using FC3S coils they have to be trailing coils (four of them all told, naturally). The reason is because the ignitors (the large metal part) can be removed from the coil (plastic part labeled T1 or T2). Then you simply disconnect the wires between the two you have a fantastic coil to use with an x4 box!

Im not up on the Lt8s joey, but if im not mistaken it has no ignition booster ( thats why it can be used with stock coils). I can't really say if the ignitors can be used with aftermarket coils, most people seem to prefer an Accel or Msd box for that purpose dont they?? intriguing!

So if i mod my trailing coils as you describe, i can wire them directly up to my microtech ignition box? Is that what i am understanding?

Yes the coils are marked + - .Take 2 sets of trailing coils pull the covers off and wire them up.

t2 trailing coil,, each 0.7 -0.8 ohms

HEC 715 =0.41 -0.45 ohms

that should be raising alarm bells to all those that "think" or "wish" the t2 coils produce a stronger spark
,, well,, this primary resistance is the corner stone in a triangle of factors used to determine the output
others include the secondary resistance and the number of winds

however,, primary resistance is pretty much the best indicator ,, and those t2 coils are not much better than generic bosch gt40 coils,, and not a patch on a HEC715 or HEC716


i know full well that leading coil SLIDFIS falls well short of the power of a trailing coil DLIDFIS,, which falls short of a bosch HEC715 DLIDFIS
( i run LPG fuel, under boost , and that soon finds which spark is weakest )


i also fit various combos to various cars according to the owners desires and get to tune them

and i know the hard way
that similar micro equipt cars with t2 trailing coil packages , stock coil packages,, and HEC coil packages all hit a different level of boost /flow before having spark issues


PS

if you blew out a HEC715,, there is a few more options--

1: try the modern versions of HEC716,, they are slightly lower again in primary resistance,, but require new leads as they have a male anode end on coil
new versions do not have the "pistol" look of old and have a revised layout to prevent arcing across the rear poles

2: if sequential ignition ECU and set up the right dwell ( more than 5.5 ms at 13v ) then MEC 723 coil or MEC 720 coil ( ca20 coil ) can get 120 mJ of spark
( while the HEC 715 is around 90 mJ at 13v and 3.5 ms )

u will still need to use the x4 if u mod the t2 coil to dumb coil,
if u whant to delete the x4 u need to use the coils that I use or any lsx style coils that take + falling edge to fire

great info Bumpstart,
si if runing MEC 723 coil or MEC 720 coil in sequential with the x4 whats the highest safe dwel to run with x4?

also have a friend with ltx8 with built in ignitors that has spark issues
wahts the most dwel you would recomend with the above coils?

the best info is in the megasquirt and Dtec articles where some of these coils are directly compared

in the Dtec ignition coil PDF
at 13.4 V, 7A current is achieved with 3.5 ms if HEC715 ,, and this is 91 mJ on the ignition coil dwell calibration paper

at 13.4 V , 7A of current is achieved with 5.4 ms if MEC 720 ,, and this is 114mJ

at 13.4 V, 7A of current is achieved with 7.3 ms if MEC 723 and this is 120 mJ

as you can see , 7a has made a different energy intensity in each example ,, and taken a different rise time

indeed ,, if you subject a HEC 715 to 5.4 ms of rise time you will have more than 9A of current,, and possibly a driver or coil failure
( but a big spark for a short period )

also to consider
,, is that a sequential ignition rotary ( CNP ) has 13.34 ms of rise and fire period between events at 9000 rpms
,, while a wasted saprk one has 6.667 ms
and total saturation periods that are longer than that are not desirable in a wasted spark application

this is why the HEC 715 was initially best choice when ECU's had inbuilt igniters and wasted spark ( digi 2 pro )
but also why there is other coil options for sequential spark high revs if you wish to play the dwell settings

its also why if you have an ECU with only duty dwell ,, it will burn some coils and not others
( cause if set for 70/30 dwell time and use as CNP or sequential igntion at low revs you can force some coils past 10A )

Wow. All this talk is WAY above me. I found my coils, they are out of a '91 N/A. Will they still work, or no? And what is an "x4" box? My microtech box is LT10S. So i'm just a bit confused about all this different talk with the coils. I did get that if you tell me these N/A trailing coils will not work, that i can use the updated bosch coils (HEC716). Now Bumpstart said that i need to rewire them because they are different. Are we talking ignition wires, or a simple mod to my wiring harness in order to literally hook up the coil?

Gotcha; ignition wires need to be different. Okay. Now, i can't seem to find anywhere online to buy any of these coils except for the HEC715. I'll have to make some calls tomorrow. I'll let you know. I think i'll try for the MEC720's if I can find them around here. If not, i'll have to Ebay myself a pair of HEC715's.

The x4 box is the igniter box that MICROTECH uses to fire aftermarket coils if you ecu is programmed to do so,if not you have to run factory coils and your na coils will work fine.

I just bought blaster SS coils since they are readily available here. Any idea what dwell time i should be setting?

Bumpstart,

finaly got the car running with the ign1a race coils with built in ignitors,
I ditched the x4 running them straight from lt10s,

so far I am very pleased with them, the car's response and drivebility is great
only at 2.75ms dwel for now, I havent boosted yet,

how ever I am having problem when I turn the ignition they fire and some time I get
small back fire,
the last back fire I had was little stronger and it bent my TB,

I thought my iac valve got stuck open but was surprised to see the tb buterfly bent at a minor pop,

is there a fix for this problem?

not sure on the dwell for msd, but make sure your x4 is still in good shape,
when i blew my coil last time the x4 went toast also

Help
 

So I know this is a very old thread, but can someone please answers this for me?: I currently have a microtech LTX-8, and old microtech/bosch hec-715 coils, as far as I know I do NOT have an X-4 box. I would like to switch to stock coils, do I have to order an x-4 box, or can I run stock coils straight off of the microtech LTX-8 like I am with the bosch coils??[/B]

Should be able to wire them straight because the LTX series are the older units with built in igniters before they switched to the X4/X6 external boxes.