Stock 400 Piston Boost

-
turbobill said:
Ive been running a stock cast piston 440,stock 452 heads with shims under the intake springs,stock 1976 new yorker cam since 1995. 6lbs boost,28 degs total timing no retard,eng cost me 5oo dol. Broke 1 cast crank balancer, makes a great cruiser .
Click to expand...
Pics please. You say 28 degrees total timing then say no retard? Seeing how the factory big blocks run best around 36 degrees N/A I’d say your about 8 degrees retarded. Which would be about 1.3 degrees per pound of boost. Sounds about right.
 
Garrett Ellison said:
I bet two 1000 cfm ThermoQuads could be heard overtop of the blower whine!
:steering:
Click to expand...
20200216_150528.jpg
 
I remember some video where a guy was doing some dyno test and it was something somebody posted here on this forum..
The point was to show how much timing affected actual horsepower.
It was almost crazy how much timing was taken out and how little actual horsepower was robbed...
and don't quote me but I remember it was something like going from 34 to 30 was like 10 horsepower loss.. and then down to 26 was like 20 or 25 horsepower loss out of the 400 plus... It was like he had to take it all the way under 20 degrees before a massive amount of horsepower was starting to get taken out..
 
Although forged pistons maybe a good answer I bet less money would be spent on a MSD box and a start retard mechanism... One hell of a lot easier too..
 
j par said:
Although forged pistons maybe a good answer I bet less money would be spent on a MSD box and a start retard mechanism... One hell of a lot easier too..
Click to expand...

Probably, but GAWD I HATE that stuff. I know how to wire it, I know how to use it. I've done it a good bit helping other people but I hate it. But you're right. That's gonna be the best way to handle it.
 
This is why I like the idea of nitrous..
when you already have an extremely powerful engine it's only at those extreme moments once every great once in awhile you want that extra boost to power.. running a turbo or a blower or whatever it's always constantly running event when you don't need it....
 
j par said:
This is why I like the idea of nitrous..
when you already have an extremely powerful engine it's only at those extreme moments once every great once in awhile you want that extra boost to power.. running a turbo or a blower or whatever it's always constantly running event when you don't need it....
Click to expand...

But this engine would be stone stock if it had a stock camshaft, so it's not extremely powerful. It's the horse power to weight ratio that's gonna be fun......blower or not.
 
j par said:
This is why I like the idea of nitrous..
when you already have an extremely powerful engine it's only at those extreme moments once every great once in awhile you want that extra boost to power.. running a turbo or a blower or whatever it's always constantly running event when you don't need it....
Click to expand...
There is a lot wrong with this statement. ^^ A turbo street engine by nature is a mild engine when not in boost. Statistically lower compression ratio, mild (ish) camshaft timing etc. Unless there is load the turbocharger is really doing nothing. A supercharger is driven by the crank, always spinning but not always making boost. Do you have experience with either one of these types of forced induction?
 
RustyRatRod said:
Probably, but GAWD I HATE that stuff. I know how to wire it, I know how to use it. I've done it a good bit helping other people but I hate it. But you're right. That's gonna be the best way to handle it.
Click to expand...
You don’t really need all that stuff but an MSD 6btm is a good idea. It allows you to pull timing in relation to boost and also keep a curve in the distributor that will make the engine completely docile when not in boost. You can do it with just a curve in the distributor (like 12 degrees initial and 28 total) but you loose a lot of the drivability.
 
TT5.9mag said:
There is a lot wrong with this statement. ^^ A turbo street engine by nature is a mild engine when not in boost. Statistically lower compression ratio, mild (ish) camshaft timing etc. Unless there is load the turbocharger is really doing nothing. A supercharger is driven by the crank, always spinning but not always making boost. Do you have experience with either one of these types of forced induction?
Click to expand...
I didn't say the engine was always under boost, it's a no-brainer that the belt is always turning (unless we're watching an episode of mad Max LOL..) or the turbo is always being blown through..
No I don't think I made any claim to know about turbo or blower motors I'm only working on theory...
TT5.9mag said:
You don’t really need all that stuff but an MSD 6btm is a good idea. It allows you to pull timing in relation to boost and also keep a curve in the distributor that will make the engine completely docile when not in boost. You can do it with just a curve in the distributor (like 12 degrees initial and 28 total) but you loose a lot of the drivability.
Click to expand...
and my point was having full potential of the motor at all times without losing one bit of driveability and having extra horsepower on top for those extra rare occasions when you want it... Well nitrous set ups are not cheap they're nowhere near they are out a Roots blower would be for an engine like that. and keep in mind he's calling from a slant 6 in a 64 Dart to a 400 big block which is already going to be a lot for him to handle.. unless he plans on tubbing it for some tires to hold that kind of horsepower it's going to be ridiculous Overkill...
 
TT5.9mag said:
You don’t really need all that stuff but an MSD 6btm is a good idea. It allows you to pull timing in relation to boost and also keep a curve in the distributor that will make the engine completely docile when not in boost. You can do it with just a curve in the distributor (like 12 degrees initial and 28 total) but you loose a lot of the drivability.
Click to expand...

That's actually the very box I was lookin at but I don't see how it has anything that would pull timing out......unless there's another box to add to it. ....and therein lies the reason I hate MSD. Once you get it, it's add this and add that.....
 
TT5.9mag said:
You don’t really need all that stuff but an MSD 6btm is a good idea. It allows you to pull timing in relation to boost and also keep a curve in the distributor that will make the engine completely docile when not in boost. You can do it with just a curve in the distributor (like 12 degrees initial and 28 total) but you loose a lot of the drivability.
Click to expand...

Nevermind, I was only looking at the first instruction sheet. I see the one on the 6BTM now. It's costly, but it'll work. I got plenty of time to save up. lol
 
The box was built in timing retard is still more costly than hey MSD withjust the built-in rev limiter and a start retard box.
And you already get the extra start feature..
 
j par said:
The box was built in timing retard is still more costly than hey MSD withjust the built-in rev limiter and a start retard box.
And you already get the extra start feature..
Click to expand...

I understand, but the start retard will not retard under boost. I'll need that for sure if I intend on using the cast pistons.
 
RustyRatRod said:
I understand, but the start retard will not retard under boost. I'll need that for sure if I intend on using the cast pistons.
Click to expand...
Again like was pointed out and I even pointed out I don't know how the wastegate and some of the other stuff for boost works.. The retard side could be activated by a window switch on a relay..
Start future can be unactivated or activated for a locked out distributor mainly...
 
I got my setup set in the back of my glove box.the start feature on the left is just a way to retard the timing during starting only and then when it reaches a certain low RPM the timing swings back.
On the right side of the box is a setting for retarding your timing when it gets a low voltage signal... So if your boost comes in at a certain RPM you can have that on a window switch which is about 50 bucks and it would only be activated at the RPM you said it to start at and the RPM you said it to stop at...

IMG_20200327_141321.jpg
 
@j par just sit back and watch. Rusty the 6btm has a built in map sensor that reads manifold pressure and has an externally adjustable dial that allows you set how many degrees of timing are pulled per pound of boost. It couldn’t be simpler.
 
The only time you would ever need a start retard is if you locked out the distributor and ran static timing at say 30 degrees. I don’t know why anyone is even mentioning it here.
 
TT5.9mag said:
@j par just sit back and watch. Rusty the 6btm has a built in map sensor that reads manifold pressure and has an externally adjustable dial that allows you set how many degrees of timing are pulled per pound of boost. It couldn’t be simpler.
Click to expand...
Well then that's what he needs...
 
@j par The wastegates are controlled exhaust leaks. Spring loaded valves with a value (X) in pounds for the spring. Anytime boost>X the valve opens and “wastes” exhaust energy, therefore no longer driving the turbine and slowing down the compressor, limiting boost to that level. A blow off valve works similarly in that it blows off excess pressure in the charge side when the throttles are slammed shut and the turbo is still spinning thousands of RPM.
 
TT5.9mag said:
@j par just sit back and watch. Rusty the 6btm has a built in map sensor that reads manifold pressure and has an externally adjustable dial that allows you set how many degrees of timing are pulled per pound of boost. It couldn’t be simpler.
Click to expand...

Yeah. I've been reading about it. That's how I'll go if this actually materializes. It's expensive, but it's one piece in one unit. This will probably all be a pipe dream anyway.
 
TT5.9mag said:
The only time you would ever need a start retard is if you locked out the distributor and ran static timing at say 30 degrees. I don’t know why anyone is even mentioning it here.
Click to expand...

Right. I knew start retard I didn't need. Why would 7.7 compression need start retard? The blower ain't turnin yet. LOL
 
You must log in or register to reply here.
-

Back
Top