how much boost can i safely run without an msd btm box? i plan to get on but at the moment i dont have one. the supercharger isnt here yet, just bought it, but id like to get things ready. also, what should i set my timing to without it? i run 16-17 degrees now with no ping. i have afr 165's and since they are alluminum they seem to be pretty forgiving when it comes to advancing timing. ive heard some people say no more then 5# abd iver heard others say they have run up to 10# of boost. i have a wide band o2 so i dont have to worry about going lean. the kit has a few pulleys, the smallest is made to make 15# on a stock motor. not going quiet that high though. id like to run 8-10#
how much boost with out msd btm
- Thread starter luckythirteen13
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txstang84
15 Year Member
most places recommend anything over 6psi you'll need a boost retard device of some kind. there are people on here that like to say you don't need a tune, but when you run a power adder it is much to your advantage, when you add boost, you increase potential for detonation a great deal more than with a normal compression (9-9.5:1) N/A engine...then again, I'm sure you already read up on that.
I'd say don't exceed 8 without a btm...just me though
I'd say don't exceed 8 without a btm...just me though
txstang84
15 Year Member
lets assume just for the moment, that you will be running 8psi, I'd probably go with initial timing of 10*...or possibly even 8* DAGGAR, or one of the resident gurus would probably be a better source for initial timing rec's
IBChillin32182
Founding Member
Well I just installed a BTM on my 92 GT today and put a 9# pulley on my powerdyne. I am running 10* base timing. I started with 2* retard per psi and have worked it down to 1/2* retard per psi and still haven't had any detonation. I ran out of time today to back off the retard any more. I may not have to run any retard at all with my current setup but I am going to keep my BTM for the hot 95-100* days we have during summer.(Today it only reached the low 80s)
Dbeck002
New Member
IBChillin32182 said:
Be careful, it only takes one detonation to ruin the engine. Dont wait for it.
millhouse
Founding Member
I've hear to many horror stories about btm's to ever buy one. If you want to do it right, get a dyno tune done. You then wont need to rely on a btm system.
Or...you could do what I did. Set your timing to 20* with the spout out...and leave it out. You should be able to run up to 14lbs of boost or so, and you wont have to worry about the timing.
Or...you could do what I did. Set your timing to 20* with the spout out...and leave it out. You should be able to run up to 14lbs of boost or so, and you wont have to worry about the timing.
I'm also a fan of the correct tune. There's no set, super secret, correct answer to your question. My combination runs 8 lbs of boost or 90 octane gas with 12* of initial timing and no boost retard in combination with a 2.2L Kenne Bell Blowzilla. I doubt seriously that I could get away with that on a non-intercooled, centrifugal supercharger. Your combination will dictate what tune and timing will be best for you. I have an LM-1 Wideband 02 permanently mounted in the car where I can keep an eye things. I started by running base timing then slowly wheening the car off of the 93 gas by filling the tank at half tank intervals with the next lowest grade gas until it stabilized at 90. Once complete, I started increasing the timing until a noticable change was heard in the engine at full boost then backed it down 2* to stay "safe". I don't recommend this method to everyone. As Dbeck002 pointed out, you can be detonating and not even hear it is some cases. It would suck to find out once the big one hit that wrecked all of your expensive parts. The sure method is to put the whole thing on the dyno and get a custom tune for the street that will be able to deal with variations in temp, humidity, etc. Cost varies, but expect to pay somewhere around $600 for the initial tune and chip. Good luck!
millhouse said:
The money you spend on the BTM will get youhalf way to getting it tuned properly. If I were tuning with a carb and wideband, I might go with a BTM but otherwise a custom tune and chip or EEC tuner is the way the go if you want it done right.How is the turbo setup going Millhouse? Did I miss an update?
well you guys sold me, no btm for me. ill just set the money aside for a dyno tune which is what i really need/want anyways. ill just keep the timing low untill i can get to the tuners. dont have any trips to the track planned and even if i did, dont really want to push it that hard without a tune.
millhouse
Founding Member
Daggar said:
Not really. I yanked the heads because I got sick of pressurizeing the coolant every time I got on it. I'll be o-ringing the block within the next few days and I'll see if I can put an end to it. Dont get me wrong...the car ran incredible! It just starts to become no fun when you have to shut her down and add more coolant because it's shooting out the overflow!
