after adding a blower when do you need a BTM?

**houstonstangguy** · 02-13-2003, 07:07 PM

after adding a blower at what point to you need a btm???

not sure if i should get it now or put that money towards something else

thanks
Joe

**Texas89LX** · 02-13-2003, 07:19 PM

[noob question] whats a BTM [/noob question]

**TheHawk05** · 02-13-2003, 08:24 PM

BTM is short for Boost Timing Management. I believe this term was coined by MSD. It's an ignition control box that retards timing as boost increases. Typically they are connected to the motor via a vacuum line so they can read boost in the manifold. Most usually have a cockpit mounted control knob so the user can adjust how many degrees of timing to remove per pound of boost.

IMO they are a must on any supercharger installation to prevent detonation. The two best units I know of are:

If you already have an MSD 6AL or Crane HI-6, both companies offer kits to upgrade them with timing retard capability.

**5150 LX** · 02-13-2003, 09:42 PM

Here's a question, if you have a custom tune or a tuner do you still need the BTM to pull out timing? I plan on getting a "tune" when I get mine back together and I am just curious if I will still need my stand-alone MSD BTM.

**houstonstangguy** · 02-13-2003, 11:12 PM

so is there a difference between say that red msd 6 btm and the blue btm that is sold with the vortech s-trim (they call it a stand alone).

thanks again

also, i heard that if you have a custom chip you dont need it. (5150lx)

**root** · 02-13-2003, 11:45 PM

The blue vortech unit is made by MSD is works the exact same way.

If you are getting a tune, or a chip, the tuner will tune the car so that it will never detonate.

Ian

**houstonstangguy** · 02-13-2003, 11:48 PM

so ian do you agree with hawk that all s/c apps should have one at least until you get a tune?

**root** · 02-14-2003, 12:04 AM

Well I used one myself and it worked great.

To use another example 93notch drove his car for 2-3 months with no BTM or MSD box, and had no detonation.

The difference is the boost, I made 10, and he made 5 or so. I think that anything above a stock install may require it. They are a very safe way to run lots of timing down low, and then pull it out up top.

So IMHO, 1-6 you will be ok 6+ I would start thinking about one. They can be found on EBAY for a nice price.

There is no replacement for common sense, good fuel and good ears!

Ian

**468LC** · 02-14-2003, 12:05 AM

I say no to BTMs. Even a safe home tune will keep you out of detonation. It might not make the most power but for the price of a complete BTM setup your well on your way to custom tuned power. Me on the other hand will continue on into the 11s with a bone stock computer and straight timing.:)

**root** · 02-14-2003, 12:13 AM

Thatta boy Steve ;)

You are exactly correct in what you said, it will not make the peak HP, but it will run no problems.

Ian

**5150 LX** · 02-14-2003, 07:42 AM

Anyone wanna buy a BTM, lol.

**Doug** · 02-14-2003, 10:00 AM

I have a BTM and a custom tune on my car. The reason I have the BTM is that my wife drives it sometimes. She has no clue what detonation sounds like, so she would never lift. She does have a lead foot and has been known to put the hurt on the occasional Vette. I think the BTM is just good insurance. You never know when you may get a bad tank of gas.
Doug

**TheHawk05** · 02-14-2003, 01:11 PM

Doug took the words right out of my mouth. I've never had a dyno tune but I understand that they can have a timing table burned onto the chip to do what a BTM does. The only problem is this: If that tune is set up to make maximum power, it won't do any good for that day you get a bad tank of gas or if the ambient temperature is good and hot one day which will both make the car much more prone to detonation. The BTM will allow you to tailor your timing for those instances on the fly.