Technical what engine oil for roots blower motor and other thoughts

So is ATF

 

Its more important to be sure you have oil in it as there isnt that much load on the gears. If you were pulling 20# of boost for 2 hrs straight, I could see some oil type viscosity warranted, But low rpm/no boost driving around town, and then an occasional "HIT" , oil is oil

 

Squirrel made some good suggestions. Basically the engine doesn't know its supercharged, it only knows it has some additional strain to drive it, and the incoming air charge is hotter, which can cause the engines overall operating temp to rise. I agree, that basically a quality performance bottom end build with some good aftermarket rods and forged pistons. Synthetic should be fine after initial breakin.
I'd suggest getting a copy of this book as it will help a lot in choosing what parts to buy for the engine.


You probably won't need a normal high performance cam as too much overlap can work against you. I'd use ARP studs to hold the heads.

 

Old Chevy rods with new bolts and resized, along with Chevy head bolts, work just fine for me.

 

I thought about head studs.
Cam will be real mild. wide lobe separation. 112 to 114.
I'm only cruising at 2200 to 2400 rpm. I want power around there more than above 3000 rpm.

 

It’s really easy to overthink this stuff.

 

With a th400 with gear vendors OD, 3.89 gears, and kind of tall rear tires, I usually cruise around 2500 (that's 70 mph). This cam works great for me.

 

That helps. I will be using a th400. 3.00 to 1 gears 9 inch ford rear. 30 inch tires.
Unsure about torque convertor ? What stall? I need to make sure it's for a blower motor.
No overdrive for now.

 

I had a similar setup in my 55 Chevy, it had 2.75 gears most of the time, but also ran 3.25 or 3.70 when I raced it, with shorter rear tires (drag radials). The overdrive saves the work of swapping rearend gears, which I did a lot of in both cars before getting the OD.

I'm running a 1800/3000 stall switch pitch converter in mine. I suggest talking to a few converter companies, and see what they say they can do. You need it to be loose enough when you want to go fast that it gets up to 3000 rpm quick, but not go over 2000 under light load when you're just driving down the road.

 

1800 to 2000 stall was my thought. The stall rating is under full power. So would I be o.k. with 2400 stall? I won't be under a load at 2200 rpm so stall shouldn't be that high. That's my understanding . I don't want to burn up transmission. I know it depends on power also. small block vs big block etc.
I like the idea on switch pitch. I currently am running a th200r4 with lockup conv.
I also have 4.10 gears 1800 stall behind a 355 chevy. Love it , gets 24mpg.
Now I want to have some fun and go racing.
I have other cars for mpg. Building the wife a 63 nova conv. When it's done the truck gets a transformation. I won't be driving it so much.

 

If you're never going racing, then 2500ish stall speed should be ok.

Just make sure the converter is strong enough, which usually doesn't take much...good turbine hub, brazed fins

 

Most street combos run "underdriven" on the ratios, so for 90% of the driving , the blower is just p***ing air and not heating up the charge. And at that point you will really have to "kick it in the pants" to start making boost.
That book cover is mis-leading because it shows a boat motor, and those tend to operate in a higher RPM range for a long period of time without any speed restriction, so at that point, a "Chiller" to cool the intake charge is beneficial. but expensive and almost worthless on a car

 

I have both the 1984 and 1999 versions of the book.

The heat thing....the blower is always moving air, but as long as the carbs are mostly closed, there will still be a vacuum in the intake manifold. As an example, you might have 15 in Hg above the blower, and 10 in Hg below, while cruising. You have to open the carbs a ways to make boost. But heat is always there. The cooling system needs to have more capacity than with an unblown engine. It doesn't matter if the blower is overdriven or underdriven, the results are the same.

Over/under has more to do with how much boost you get from a specific engine displacement and blower size.

 

With a race car, blown with gas, (land speed) a separate cooling water tank is used for the chilling of the air underneath the blower, In boats the water pickup flow is directed thru the chiller first before the engine, but for a car without a separate cooling tank, You are flowing HOT (radiator) water thru the chiller heating up the air as its p***ing thru maintaining the heat or heating it even more. your cars heater is a prime example, The fan blows outside thru a small core that once the water from the engine heats up transfers the heat inside the vehicle. Engine heat comes from accessory drag/load, A/C, P-S, Alternator and not from heated air under the blower. The only thing the extra heat does is promote detonation, as the fuel temp rises as the fuel has been converted into a vapor. The nice thing about running Alc as a fuel, that the fuel temp at the port entry is around 64* and the sheer volume of fuel pulls any heat away from the blower itself, they can even get ICE to form on the case.
Overdrive/Underdrive determine how soon full boost will occur at the hit of the throttle once the rotors start the compression cycle begins. I can take my blown dragster with 18% overdrive from idle and slowly raise the rpm to 2400-2500 rpm without the boost gage moving. but when I snap the throttle open from an idle, the instant rpm rise starts the compression cycle and a boost of 12# is registered

 

25 years of racing says you are wrong. . Some fuel has to go thru the blower to seal the rotors and keep the strips lubricated or it will gall the rotors, has nothing to do with heat. My time slip is an indication of when blower boost comes in with regards to overdrive. My 60' time increases when the lower OD is used, but still produces the same boost at the end and my blower only puts out 22# whether its at 5% or 20%. Its the compressed air in the manifold fighting back against the rotors thats creating heat. Real world short burst street driving, heat is not the issue but the cyl. pressure is because in effect you raised your CR well above any gas octane level unless you run VP-14

 

you might find that things work differently on a street engine with boost around 5-10 psi.

 

I plan on 8-71 because they run cooler than 6-71 so I've heard.
No spacer. Fuel on top so rotors will be wet .

 

What about alternator mounting? Short water pump.
Nothing else .

 

I made my own.

 

Fastcar - A larger blower can run cooler than a smaller one, if it is underdriven to move the same amount of air. Slower blower speed = less heat.

 

but what boost level do you have to get to for it to be noticeable?

 

With the steering box in the way I mounted my alternator on the p***enger side. The fuel pump boss was cut off and smoothed, holes plugged with core plugs and one simple bracket was made for belt adjustment. Before anyone asks, yes, the radiator hose fits fine. Your Model A frame might be too tight to fit an alternator there though, but you might consider a smaller one from a foreign car.

 

I had a Turbo on my Chevy (305ci)El Camino, 3# would set you back in the seat. As long as you keep boost down below 10# , you could use stock head gaskets

 

Yup, but he's doing something with it that isn't really what the OP in this thread is looking for.....

A 6-71 works fine on a street big block with 427-454 cubes. If you want to run an 8-71 for some reason, it'll work fine, also. If you're going for a traditional look, the 6-71 is usually a better choice.

 

Books and Dynos have never won races
Read your little chart again 350 @ +15% (the + means "overdrive") is 15# not 6# of boost.
The only caveat to running a larger blower, is to make sure you have enough distributor clearance between the rear cover and the distributor body, otherwise an offset will be needed

 

Read & research , size your blower/ supercharger ( Airpump) to your combination your building or have ,
There is difference from case to case
Designs ,even same series, rotor design, intakes ext ,a spacer between case & manifold helps temps in plenum, longer runners are better then short,
Back in early 90s ran a 700 plus combo SBC before bearing Technology on steel rods , changed rods every 3,000 miles & mains every 6,000. Engine was pounded on pretty much daily,
Then dont forget about Transmission combo, 2,700-3,200 pd vehicle with traction,
Converter $800 up
PG , 350,400 first internals parts upgrades purchase will be
Around if you can do your own build
$2,500 & up for around 600- 850
Over 850 ,$4,000 plus
Don't forget about drive shaft , joints axle gear,
In p*** there a few around my way , we would spray nitrous cool the charge ,
Im my current combo , i have Egt in intake to a industrial gauge that can send a signal , when manifold air temp get to set temp in a pull , I , it inject methanol ,

 

huh, I guess I don't spend enough money on TH400s

 

Hey @ekimneirbo , you have certainly come a long way in a short time. 5 months from this......

You have certainly been doing a lot of reading..........

 

NA , No rotors ,( carb inside) 6:60 in 1/8 in the 1980s chopped & channeled
Street driven all over the east ,all steel..

 

Jim, yes 400 is strong , what is your tear down / freshening ? I would think your 500ish tq & how often on Stickies.
In p*** you do not agree with p***es out side of a track ,
I guess most do not put 20 or so p***es a week on hooking set up , ot
400 trans 3,500 406 10psi.
Spinning is not hard on transmission/rear ,NA & 427 350 trans , I was able to get away with a s10 rear until drag radials close to 255 tire ,
2750ish weight .