jim in seattle
Well-Known Member
Okay- new guy here so bear with me. What type of cam would you use on a supercharged 'street /driver' motor?
And why keep compression low? What do you call low? Is it in relation to the amount of boost?
School me on supercharging a 360
- Thread starter Coyote Jack
- Start date
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Okay- new guy here so bear with me. What type of cam would you use on a supercharged 'street /driver' motor?
And why keep compression low? What do you call low? Is it in relation to the amount of boost?
I hear ya there, but be careful of Grinder will grind you and then say use'em.
That would be me. Regulate the boost and timing and this isn't a problem from how I understand it. Reguardless, your forcing the air through, so the heads flow isn't as critical as a N/A engine.
Of course, the search for more power would leed to ported heads and maybe higher PSI?
I so agree. Just do the homework and build it!
fstfish66
Well-Known Member
ok i didnt read all the previous hoopla,,
but i do know a little about street blowers,,and before i type a hole bunch of stuff,, ill say this last time ( few weeks ago) same topic,,went back and forth, at the end the person asking the same questions had this to say,,
' ILL HAVE TO SAVE MY PENNIES A WHILE, ITS LIKE 6 TO 8 GRAND TO DO THIS '
read it and read it again,,a average roots style blower motor for the street that is going to start,and run with out coaxing the throttle till the blower builds some heat in it to idle ,,because its costs to much to set the carbs up properly ...
now if you want a complete ready turn key blower motor for the streeet thats affordable go to BIG ALS TOY BOX web site,, he builds all makes,, he is not just a chevy guy,,and that what you are going to find at your local speed/machine shop.,
there are several stand alone items you will need that your not going to find used for a small block mopar,,at your local swap meet,, so gettign a complete set up,with carbs set up properly,,pullys that make every thing line up,, and an intake,, the price of an almost true blower intake alone will make you re think all this,,,
if you decide this is for you and your serious make sure you run a harmonic balancer,,an after market one not a 2 piece factory balancer,, it makes a difference when getting all the pullys worked out,,
i was lucky enough back in the mid 1990s to find my set up used pieces here and there that were all on this motor at one time,,,
i consider my engine almost bullit proof,,was built at an engine shop not a chevy shop,,,my block was re worked X block,, because the orignal owner of this block took it to a chevy speed shop,,and it was butchered, it was a new X block
i took it to a race shop that builds roundy round motors,,they know how to make a motor live,,, they build motors for people like kinser,,,
this motor is a mild street motor and in the mis 90s was 6 grand,including the used parts i was lucky enough to locate,,but didnt enclude blower carbs,,
if 600 HP is what your after easy with a blower,, but also easy with a 360 stroker,,and probably less money,,
if your seriuous ill tel you what ive been able to learn,,about building it properly,,by all meens if you call BDS,,, use your own judgement,,
but i do know a little about street blowers,,and before i type a hole bunch of stuff,, ill say this last time ( few weeks ago) same topic,,went back and forth, at the end the person asking the same questions had this to say,,
' ILL HAVE TO SAVE MY PENNIES A WHILE, ITS LIKE 6 TO 8 GRAND TO DO THIS '
read it and read it again,,a average roots style blower motor for the street that is going to start,and run with out coaxing the throttle till the blower builds some heat in it to idle ,,because its costs to much to set the carbs up properly ...
now if you want a complete ready turn key blower motor for the streeet thats affordable go to BIG ALS TOY BOX web site,, he builds all makes,, he is not just a chevy guy,,and that what you are going to find at your local speed/machine shop.,
there are several stand alone items you will need that your not going to find used for a small block mopar,,at your local swap meet,, so gettign a complete set up,with carbs set up properly,,pullys that make every thing line up,, and an intake,, the price of an almost true blower intake alone will make you re think all this,,,
if you decide this is for you and your serious make sure you run a harmonic balancer,,an after market one not a 2 piece factory balancer,, it makes a difference when getting all the pullys worked out,,
i was lucky enough back in the mid 1990s to find my set up used pieces here and there that were all on this motor at one time,,,
i consider my engine almost bullit proof,,was built at an engine shop not a chevy shop,,,my block was re worked X block,, because the orignal owner of this block took it to a chevy speed shop,,and it was butchered, it was a new X block
i took it to a race shop that builds roundy round motors,,they know how to make a motor live,,, they build motors for people like kinser,,,
this motor is a mild street motor and in the mis 90s was 6 grand,including the used parts i was lucky enough to locate,,but didnt enclude blower carbs,,
if 600 HP is what your after easy with a blower,, but also easy with a 360 stroker,,and probably less money,,
if your seriuous ill tel you what ive been able to learn,,about building it properly,,by all meens if you call BDS,,, use your own judgement,,
For what I understand, you would use a low comp. ratio because your forcing more air in. Upping the cylinder pressure like it has more compresion. So you don't start with a high compresion and add more.
A cm with a wider centerline (And it's timing of the events of the blower cam) help trap more of the charge of air and fuel. A narrower centerline cam, like typical 110 centerlines allow the air and fuel to escape since theres more overlap.
A low ratio for these engines I have seen recomended starting at 8.5-1 and lower. I don't know how high of a static ratio you can start with and then add pressure and/or how much pressure.
Whoops, my bad, I should've stated static compression. For a street motor, go 8 to 1 or a little lower. On the cam, alot of folks sell "blower cams" that have a huge seperation angle. Try to keep it tighter. Talk to the guys at Hughes or Clay Smith Cams. One of my best friends builds quite a few blower motors and goes on in detail about these things, I am no expert at it myself but the info seems to be sinking in to some level or another. I'm wiring a 38 Chevy for him right now that he just finished a blown big block motor that pulled an honest 800 horse on the dyno. (Trust me, he's been showing me that dyno sheet for a month now.)
fstfish66
Well-Known Member
[a blower cam that makes tons of power will be in the 114 center line area,,but it also makes the motor make a lot of added heat,,a 112 center line is streetable,,remember you have to keep it kool a lot of street blower motors over heat all the time,,,, i drive my cat to cruise nites 70 or some times 100 miles away,,last week 103 out my motor never went over 190,,,usually runs 170 around town,,radiator,,and cam,,,/COLOR]
Jesus fish, what took you so long to get here?
fstfish66
Well-Known Member
i know sorry,,,it just kept comming out of my head as i typed,,,,sorry,,,just trying to get the point acrossed to do it right even mild,,aint CHEAP ok ill be queit sorrrrryyy
My amigo Jerry finished up a blown 360 in a 33 Dodge sedan that was an absolute hoot to drive. I can hit him up on the cam specs, but I want to say the centerline was in the 110 range.
No frog no, don't be quiet. You are one of the good peeps who knows what's what.
OH yes, do tell. I'm all ears!
TT'74
Well-Known Member
Like most people i didn't filter through the BS in the beginning but I hope this helps.
For comparisons sake, the '94 5.2l magnum in my duster is running the stock rotating assemble about about 10psi with out any problems. The are hyper pistons not forged and about 9.4:1. I know of stock 5.9l magnum rotating assemblies that have been consistently street/track driven at 15psi. Granted these are turbod not S/C'd but the premise is the same.
How much static compression you run will have an opposite effect of how much boost you produce. More compression=less boost and less compression=more boost. There are pros and cons to each.
At a higher compression ration each lb of boost will produce more power than a lb of boost for a lower compression engine. But you're limited to small pressure levels because of risk of detonation
At lower CR though each lb doesn't count for as much you can run much several times more boost than a high CR engine. Obviously the more you compress the air the hotter it will become so cooling the charge will become a large issue as large PSI is reached. Also percentage of power gained per lb will decrease at very high pressures due to flow characteristics and burn efficiencies.
WOW! Thanks! (And sorry for the bullshit)
Very interesting reading. One thing that I haven't seen is opinions on exhaust. It seems to me that standard 1 5/8 inch tubes won't be up to the job for headers and I would want about 3 inch pipes.
Jack
Jack
I would think about the projected HP output of the engine and go from there. In example, a mild supercharged build can use a standard header. just like a mild N/A built engine and so on up the HP ladder.
IMO, a tti header would be the best option for a street duty car for ground clearance issues over the 1 size fits all header that has never really worked well in the street for us. There are a few guys useing this header on there every day cars to 10 second runners.
After the header, again, power output should help determin pipe size for the rest of the exhaust.
How much power do you intend on making?
IMO, a tti header would be the best option for a street duty car for ground clearance issues over the 1 size fits all header that has never really worked well in the street for us. There are a few guys useing this header on there every day cars to 10 second runners.
After the header, again, power output should help determin pipe size for the rest of the exhaust.
How much power do you intend on making?
I am thinking somewhere in the 500 to 600 HP range. I can see I am really going to have to research this whole setup. I was doing some reading on a couple of the supercharger sites and a couple of tech sites and the popular belief seems to be that you can start with a stock block. If that is the case I might start with a 5.9 Magnum block. That way I already have a roller cam setup and I would want to use an electric fuel pump anyway.
Jack
Jack
TT'74
Well-Known Member
Research is your best bet, because none of us know what you want as well as you do. With a 5.9l magnum motor 500-600 can be had with a very mild build. It should take about 13psi on the stock rotating assembly with a good tune. I'm bias, but if you're going to an electric fuel pump and a magnum engine anyways I would say go full FI. If its something you elect to do it's very affordable if you use a factor harness and OBD2 comp. The OBD2 computers are readily tunable and have a pretty large following with the dakota/durango crowd. So alot of the ground work is already laid out for you with plenty of help.
I don't mean to hijack, if you have any ?'s about the FI or boost that i can help with PM me any time.
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http://www.thesuperchargerstore.com/products.html
http://www.thesuperchargerstore.com/Kern Pressel.html
http://www.thesuperchargerstore.com/products.html
http://www.thesuperchargerstore.com/Kern Pressel.html
64physhy
Well-Known Member
I think if you're doing a supercharged Magnum with roller cam, you could shoot for more than 500-600 HP.
TT'74
Well-Known Member
Why would you suggest that? 500-600 can be very streetable and still maintain good mileage. If someone begins exceeding that it is easy to loose one of both of those desirable qualities for a driven car.
64physhy
Well-Known Member
But that can be attained without supercharging it. What I'm saying is, if he's spending the time and money for a supercharger, he might as well go for more. I would think that a supercharged car with over 600HP could be as streetable as a NA car with 500-600, but then again, I've never had any experience with a supercharger, other than on my waverunner, but I'm sure that's totally different.
dont forget about the twinscrewblower they can make a ton of boost without adding alot of heat just like a centrifugal but they still make cracy power down low as a roots,and they have a whine all of there own 
honestly these are not cheap and there is nothing that can be bought and installed out of a box for them but i think they are the coolest thing around
im shooting initiatily for 8-10pounds of boost on a stockblock 340 with a small solidroller and eddyheads running E85 with 9.7:1compression i may push it upwards 14pounds if i feel a need for it but im pretty sure that will shorten the life of my stockblock seriously
honestly these are not cheap and there is nothing that can be bought and installed out of a box for them but i think they are the coolest thing around
im shooting initiatily for 8-10pounds of boost on a stockblock 340 with a small solidroller and eddyheads running E85 with 9.7:1compression i may push it upwards 14pounds if i feel a need for it but im pretty sure that will shorten the life of my stockblock seriously
TT'74
Well-Known Member
It can still be streetable above 600, 500-600 if done right will sound nearly stock. If he does elect to go with a stock magnum block they are good to right about 600-700. Thats the neighborhood that block failure is a very real risk. I guess you're right, too me i was thinking budget and said streetability. My college budget can't factor in an R3 block.
I went back and reread nothing was stated about what the car will be used for. Is this gonna be a driver, strip car, or street/strip?
Lots more questions to answer and ask. This will primarily be a street car. Probably a 71/72 Demon. I am no different than anybody else, I would like to do it as cheap as possible.
As far as the Magnum setup, I was picking it because it is readily available for cheap. Being able to use the FI and computer would be a bonus as far as street manners are concerned but I am not in the know how to set that up.
The car would be setup to be able to go to the strip but that would be because I can do any of the required fabbing myself. After building my first Demon, my garage is setup pretty good for building another car.
Jack
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