As Derek and Larry suggest, warmer is better. No cooler than a 180* thermostat, ideally the OEM temperature of 195* is best for overall efficiency and longevity. You can adjust your dynamic compression and grade of fuel to use (premium no doubt) for use with a 195* thermostat for best results. What matters here is dynamic compression and cam overlap with scavenging to figure where a safe area to place static compression for use with a 195* stat. If it turns out that you can't get it tuned right to run properly on premium pump gas, you can take the stat down to 180*. A dynamic compression of 7.75:1 is ideally suited for use with 93 octane at sea level and an operating temperature of 210*. Details for all this can be listed out later on if you're not familiar with any of this. There are some very knowledgeable people here on this forum, so you're in good hands. Gary
All of the comments regarding theory on emissions and engine life are true, in theory. Improper tuning or deviation from stock throw that way out the window anyways. I'm seeing life greatly exceeding 125-250k miles with 160* thermostats in fairly wild builds with tear downs and inspections (not needed) done over many years of this. Examples include blocks with softer iron than some makes and more wear due to COLD operation and std ring tension than thermostat temps. Running temp is one of the lowest hanging fruits of octane tolerance. I guess you need to decide, "how much life are you looking for" and to what degree of built in detonation deterrence you want? Oh, my point was that you'll wear out many more components than the bores on a performance build being driven on the street.
Picked up the radiator today. Was told that the 195* thermostat would be better than the 160*....I just don't like the fact that the transmission oil will also be that hot. I will try to find a 180 or 185* thermostat tomorrow. (Happy medium) If I can't find one, I will just drill a couple 1/8" holes around the outside of the thermostat.
Also went ahead and bought an MSD Blaster 3 coil with bracket, MSD 6AL-2 ignition box, and a set of 8.5mm super conductor wire set. Changed our minds on the box after considering the price, and the intended use. Changed our minds on the coil, as it's just easier to install the round coil right in the factory spot......oh, and because of the price.:laugh:
I would just buy some nice wires and a Crane XRi points replacement. It keeps all the stock wires and coil. All you will need.
What's nice about the 6al-2 is you can customize the timing curve all from a laptop. Just lock out your distributor as the instructions state to do and you never have to mess with it again. If you are concerned with Trans Temps I would run a separate transmission cooler in series with the radiator. It will allow for much greater cooling but will also help warm up the transmission fluid when its cold and first passes through the radiator.
Didnt know that about the 6al-2...thought that was only on the "Programmable" MSD 6-Digital? Thought everything was adjustable from the outside of the box on the 6al-2? My son picked up a 180* stat the other day. Home day tomorrow...got lots to pick up, and hook up this set off.:grin:
There are two 6al-2 ignition boxes, the 6421 and the 6530 The 6421 has selection dials on the box and doesn't control ignition timing The 6530 is programmable and you can apply a timing curve to replace the distributor mechanical advance. There is another map that subtracts timing based on manifold pressure that can be used with boost or it can be used as vacuum advance. It Also has a step retard for nitrous or if you simply want to pull some timing out for high gear. Paul
We bought the 6421 model, along with the Blaster 3 coil, MSD 8548 Pro billet distributer, and MSD 31193 wire set. (Hope there is enough extra wire in the set to make a coil wire.)
I noticed the distributer didn't have the vacuum pod on it... We are building the engine for more power, so fuel economy will suffer. Probably won't have a bunch of vacuum anyways with a stage 3 or 4 cam. (Still undecided)
As far as I know there is no provision to add a vacuum advance pod to that distributor. Vacuum advance adds around 8 to 10 degrees to the mechanical advance and can put the total timing out to 45 degrees BTDC during cruising conditions. You can't make up that difference any other way because the total mechanical advance plus the initial timing should not be more than 34 to 36 degrees BTDC. The initial timing will be determined a lot by the amount of valve overlap in the cam timing. The more overlap, the lumpier the idle and the more initial timing is needed so the engine doesn't stumble from a standing start. The final timing at 3000 rpm without vacuum advance should not be more than 34 to 36 degrees. The ramp rate in between or the rpm when the mechanical advance is all in is determined by your mechanical advance spring selection and should be in as soon as possible without engine knock or ping. It will depend a lot on the compression ratio and gas octane
Some efi setups will add in a simulated vacuum advance during low load cruise situations such as the MSD Atomic efi. It's a pretty neat feature
So will the 6AL-2 PN6530 that you made reference to back in post #27. Just install a 1 bar MAP sensor and use the BOOST/RETARD Map to map the vacuum advance. Paul
IMO, any street car should have vacuum advance. The MSD wire kit includes a coil wire, you do not have to make one.
Well thats kinda what I figured. Everyone always talks about having their timing "All in at ~2800rpm, 36-38 total" So I didn't think we would need the vacuum advance for stop and go traffic/jack in around. This is his play car, like I mentioned in my post after I edited it...there may not be enough vacuum with the stage 3 or 4 cam anyways. (Would like to look at roller cams too.)
Better to have something and not need it, then need it and not have it. Not a good idea to burn your bridges. IMO, any street car should have vacuum advance. All in timing is 30-34* in most cases. That is the sum of initial + mechanical timing. Be very careful about your cam selection. Bigger is not always better, and there is a lot more that needs to be considered when selecting any cam. BTW, what is a Stage 3 or Stage 4 cam? You want to build a car to jack around in stop and go traffic? Why would you want a big cam for that? A big cam will get old really fast especially if you don't have the combination right.
Crower stage 3 or 4. Waiting for the TA aluminum heads to come out before we do the engine internals. He wants a lumpity bumpity cam...he's only 17....he doesn't seem to care too much about what it looks like...just make it a beast. The car needs a frame off IMO, but it's not mine, it's his. The cost of the body work alone would keep him broke for years...
OK, cam 101. The higher you can spin any engine, the more HP it will make, IF, and this is a big IF, it can breathe at that higher RPM. That is the reason for selecting a bigger cam. The bigger cam holds the valves open longer so the engine breathes at higher RPM. There is a downside to a bigger cam though. You gain the ability of the engine to breathe at higher RPM, but you lose lower RPM power and torque, and the engine idles rougher. The smaller the displacement of an engine, the more lower power is lost. A moderate cam in a 455 might act downright huge in a 350. A big cam will want bigger gears and converter, and all of that makes the car less driveable on the street. The engine won't make the power you expect until you get it up in RPM. That isn't going to happen stop and go around town. You could potentially end up with a car that sounds lumpity bumpity but gets it's butt handed to it by a Honda Civic at a traffic light. 17 year olds all have big eyes and no patience. If you want a hot street car, get the best heads you can afford. Head flow is way more important than cam size in a well thought out street car. A smaller cam is way better for your purposes.
