Supercharged 212cc Think Tank / Idea Board

[Denny]

Bob you are way overthinking this and sending yourself down a rabbit hole of no escape. On street or race vehicles with a Roots type supercharger compressor NO blow off valve is needed or wanted. However on the intake manifold an explosion plate is used. What the explosion plate or valves purpose in life is if there is a backfire in the blower instead of blowing the supercharger off the engine and into orbit it will vent through those opening saving many $$$ in repairs. I think where you are getting confused is when you use a centrifugal supercharger or late model cars where fuel economy and emissions is important then they may bypass and recirculate the air.


Denny

 

[bob58o]

Well this isn’t as flexible as I hoped.
The non-reinforced stuff has the flexibility I want but was only rated for 25 psi (10 lbs boost).

I need to route flexible hose from the output of the blower to the intake manifold. If heated, this MIGHT work.

Wonder what vacuum cleaner hose is rated for?

I will continue to search.

 

[bob58o]

The hotter I make get it, the more flexible it becomes But it is pretty rigid when cool. Hot compressed gas from the blower should keep it warm.

1.62" OD vs 1.75" OD
Walls 0.065" thiiner
http://www.usplastic.com/catalog/it...Isb9iMDo2O7jsRyXubeFFOOG4ehi31MoaAuISEALw_wcB

1-5/8 in. Outter Diameter x 1-1/4 in. Inner Diameter x 2 ft. PVC Clear Vinyl Tube
https://www.homedepot.com/p/Everbil...-PVC-Clear-Vinyl-Tube-HKP001-PVC019/303132509

SILICONE HEATER HOSE, 1.25" ID, 1.64 OD, 0.200 WALL
https://www.siliconehose.com/silicone-heater-hose-1-25-id-1-64-od-0-200-wall/

Haviland Vac Hose for Above Ground Pools, 18-ft x 1-1/4-in
https://www.amazon.com/Haviland-Abo..._n_feature_keywords_two_browse-bin:6886115011

Patriot Flexible PVC Pond Hose 1.25" x 25'
https://www.amazon.com/Patriot-Flexible-Pond-Hose-1-25/dp/B00B0YLYHI

 

[bob58o]

This was a thread I found on another forum...
To support you guys.

"I'm talking about all those systems where the supercharger is not clutched and where the throttle is in the inherently safe position upstream of the supercharger.

A roots blower does not consume much power when it runs in a manifold pressure that is typical at closed throttle.

The bypass valve synchronisation problem does not exist if the blower is not clutched and there is no bypass.

The bent throttle shaft problem does not exist if the throttle is upstream.

I can understand OEM investing huge resources and going to all the trouble to squeeze some extra power out of a restricted space and still retain reasonable economy, but a hot rodder chasing maximum power is really wasting a lot of time and effort and really decreasing safety to save a minimal amount of fuel.

To be frank I really can' be bothered contributing to this.

I also noticed the vast majority of real professional knowledgeable full time working professional engine designers are not bothering with this thread. You might ask why."
--------------------------------------------------------------------

I think where you are getting confused is when you use a centrifugal supercharger or late model cars where fuel economy and emissions is important then they may bypass and recirculate the air.

Denny

I was talking about Positive Displacement Draw-throughs.
And i also was considering blower placement with respect to the throttle and the valve
Eaton. Magnuson. Whipple... have them, some cars since at least '92
But probably added for fuel economy/emissions reasons.

I think my misunderstanding might have been that I was assuming positive manifold pressure would remain even with the throttle closed. Not thinking how closing the throttle, limiting the air, means greatly reduced pressure at the intake valve..

Bob you are way overthinking this and sending yourself down a rabbit hole of no escape....

"After this there is no turning back. You take the blue pill, the story ends. You wake up in your bed and believe whatever you want to believe. You take the red pill, you stay in Wonderland, and I show you how deep the rabbit hole goes."

https://www.youtube.com/watch?v=uGQF8LAmiaE

https://www.youtube.com/watch?v=8OGn2CK8dOo

 

[bob58o]

I still don't think the Rabbit Hole is that scary, provided the valve's adjustability works within the vacuum range of the engine.
And ALSO I haven't yet ruled out clutching the supercharger.

If Manifold Vacuum turns out to be something like 15" Hg at idle, 10" Hg at cruise, and 20" Hg upon Deceleration -

I can set the valve for 10" and only have boost when the throttle is open more than "cracked".

Idle (15") - Recirc. Valve open
Cruising (10") - Recirc Valve Open
Deceleration / Coasting (20") - Recirc. Valve Open

Anytime the vacuum reads 10" Hg or less (meaning more throttle than slightly cracked for cruising), the valve closes and I am no longer using the bypass.

Or I can adjust the Valve for for 14" Hg.

Idle (15")- Recirc. Valve Open
Cruising (10") - Recirc Valve Closed - No Bypass
Decel / Coasting (20") - Recirc. Valve Open

Valve is only open at idle and upon deceleration and coasting. Won't BYPASS unless vacuum is idle level or above, so you won't have the bypass open when cruising with a slightly open throttle.


Or I set the bypass valve for 18" Hg.

Idle (15") - Recirc. Valve Closed - No Bypass
Cruising (10") - Recirc. Valve Closed - No Bypass
Decel / Coasting (20") - Recirc. Valve Open

In the last example, the Bypass is only open when I let off the throttle after accelerating or cruising. It would close as the engine returned to idle.
Which may sorta replace the "burst plate" and protect against a backfire??? - Manifold won't be pressurized, and air is circulating, but there would be no escape to atmosphere with a Bypass instead off a Blow Off Valve.

The burst plate seems more like a wastegate?? Operating off of manifold pressure vs a BOV or Bypass Valve which operates off of Vacuum Signal?

 

[Denny]

Somebodys been watching too many Fast and Furious movies!


Bob, Sorry but some things just can't be done with a lot of math and thinking. Just put the blower on as close to the intake valve as humanly possible, underdrive it by 20%. Mount the carb as close to the blower as possible. And be done with it. If it wants more boost it will let you know, if it wants less it will let you know that too. That is the best advise anybody could give you at any price.


Denny

 

[ezcome-ezgo]

Don't take either pill, silly. Just stand in the lake revving your engine.

 

[bob58o]

I was looking into compression ratio, camshaft profile, and head design for Positive Displacement Forced-Induction Engines.

CAMSHAFT
Most places suggest a mild camshaft (not too much duration 230 Intake, 245 Exhaust) with the single most important thing is extra (~10%?) lift and duration on the exhaust. The blower forces the air in, but the extra exhaust lift and duration helps get the air out of the cylinder.

Look for something with wider LSA (112 to 114) and little overlap (< 30 degrees).
Tighter LSA, or More Overlap (which helps scavenging at higher RPM), allows the intake charge to be blown out the exhaust.
I was thinking NR Racining's 280 series.
Lift: 0.280"
Duration (0.050"): 220 degrees
ICL: 106 BTDC
LSA: 111 degrees
With a 1.2 Ratio Rocker on the Intake and 1.3 Ratio Rocker on the Exhaust.
So 0.3384" Intake Lift and 0.364" Exhaust Lift, since I can't find a cam with more exhaust duration - I'll use the ratio rockers to get extra (and more rapidly opening) lift.
Have to work out max lift once the desired static CR is figured out and the parts needed to achieve that.

CYLINDER HEAD
-Focus on the exhaust port. Positive Pressure will help overcome minor restrictions in the intake port, but hogging out the exhaust helps get the air out of the cylinder (plus a wide free flowing exhaust).
-A multi angle valve job will help cool the valves.
I was thinking about a 22cc clone (non-Hemi) Head with 28.5mm / 25mm Valves.


COMPRESSION RATIO
The Bigger the combustion chamber, the better. Lower static CR means I can run more boost. More boost means more O2. More O2 means more fuel. More Fuel means more power. Low CR with High Boost makes more power than High Compression Ratio with Low Boost due to there being more O2 molecules present. Looking into Crank, Rod, Piston, Gasket combos that might give me around 7.5:1 Static Compression and try for around 12 lbs of boost. Or stock is around 8.5:1 and I could run 9 lbs boost. I was thinking about alky, figure the methanol will cool the intake, since there is no intercooler. Wondering how alky plays with the innards of the roots blower. I think Funny Cars use roots blowers and nitro? Or maybe I'll use 110 Octane? Or maybe water/methanol injection?

LOL - No fast and Furious, just Youtube - mostly Monty Car Mods.

 

[bob58o]

Bob, Sorry but some things just can't be done with a lot of math and thinking.

Denny

I do all my best bench racing with math and thinking.
The math says I think I'm the fastest.

Without a bypass, the plumbing is pretty simple.

Carb (35mm spout)
https://www.aliexpress.com/item/KOS...-ad60-417e-9fce-f20c42bd34ef&rmStoreLevelAB=5

Silicone Reducer (35mm to 48mm) 3" in Length
1-3/8" to 1-7/8"
1.875" to 1.375"
http://www.siliconeintakes.com/intake-pipe-reducer/pipe-reducer-p-90.html

Blower (48mm Intake, 48mm Output)
https://www.aliexpress.com/item/Car...-Displacement-0-8-1-8L-model/32273549916.html

Silicone Reducer (48mm to 32mm) 3" in Length
1-7/8" to 1-1/4"
1.875" to 1.250"
http://www.siliconeintakes.com/intake-pipe-reducer/pipe-reducer-p-89.html

32mm OD Hose Joiner 3" in Length
https://www.amazon.com/Boesch-Built-Aluminum-Silicone-Coupler/dp/B0089E3BZK

32mm ID Flexible Hose
???????
Maybe Rated for 20-30 Inches Hg? 30-50 psi?
Flexible enough to get to manifold.
Maybe in combo with a 90 or 180?
Maybe flexible Radiator Hose?
https://www.ebay.com/itm/24-Flexibl...tainless-Steel-w-Chrome-Caps-V8-/253171130580

32mm OD Intake Manifold / Carb Adapter
https://www.nrracing.com/product-p/man-24-wp.htm

 

[bob58o]

Getting it to fit a Minibike is the struggle.
Might fit on top if I have 16” + from motor mount to top bar.
It will give a higher COG.

Might fit in front of the engine on a drag bike like the Nitro 50?
With the engine near the rear, there’s more room for the carb to stick out to the front. Keeps COG lower. Moves weight towards front, to help keep the front wheel down. Or Maybe I’d need to 180 the carb?

If off to the side and in front, my leg might be in the way?

Might fit better behind the engine on a Minibike if there’s room between the engine and the wheel?

https://youtu.be/TJTQ_XO3NK0
https://youtu.be/sNJxxNT9HgY
https://youtu.be/XyRAUoKbceM

 

[Forge fixer]

supercharged 212cc

Bob you are dealing with a $100 engine just put the supercharger on with engine completely stock except the governor and carb . I highly doubt it will blow up at 12psi. I've seen a predator take a few more psi with another method of boost.

 

[bob58o]

I ordered some silicone Reducers.

48mm > 32mm
For reducing the output of the blower to match the intake manifold.

48mm > 35mm
For increasing the carb output to match to blower intake.

I got the 48mm > 32mm reducer.
And the other one is 51mm > 45mm.
I like ordering online. When I get the stuff I order.

Hoping the 48mm output that I was told is correct.

 

[Denny]

Bob, what are they soaking you for that blower? One other thing I should have mentioned if it were me I would upgrade the rod also. With the blower you have to remember the engine will be under a load anytime it is under boost. Also I would not use convoluted tubing of any kind, it will screw with the air flow.


Denny

 

[bob58o]

Bob, what are they soaking you for that blower? One other thing I should have mentioned if it were me I would upgrade the rod also. With the blower you have to remember the engine will be under a load anytime it is under boost. Also I would not use convoluted tubing of any kind, it will screw with the air flow.


Denny

The AMR300 is $236 shipped.
The AMR500 is the same price, but too big for a 212cc. Either one could work on a 420cc. Overdrive the 300 (hotter intake temp), or underdrive the 500 (blower less efficient when turning slowly).

Rod and Valve Springs minimum.
I'd like to do a cam, ss valves, cr-mo pushrods, HD rockers, and a forged piston too.

I think I'm going to get my blower a little blue hat and find out what these guys have for a job title.
https://www.youtube.com/watch?v=FWohMqeT0Cg

 

[jhuckstead]

Just an idea... What about using the stock carb with the throttle plate removed... Then put a throttle body between the supercharger and the engine... They do sell throttle bodies in those EFI kits from Ecotrons

http://www.ecotrons.com/products/small_engine_fuel_injection_kit/

Or leave the throttle plate in and rig both throttle bodies together. That way the idler jet still functions normally.

 

[bob58o]

Not 100% sure, but I don't think that would work. Pretty sure for a carb to work properly there needs to be a throttle inside the carb. How would an idle circuit work in the carb without a throttle?

I would need a bypass for sure, and don't really see any benefit.

---------- Post added at 08:06 PM ---------- Previous post was at 07:33 PM ----------

Anyone a member over at YellowBullet.com?

I tried to join and completed my activation, but I've been in a que to get added for about a week now?

 

[Kartorbust]

Just an idea... What about using the stock carb with the throttle plate removed... Then put a throttle body between the supercharger and the engine... They do sell throttle bodies in those EFI kits from Ecotrons

http://www.ecotrons.com/products/small_engine_fuel_injection_kit/

Or leave the throttle plate in and rig both throttle bodies together. That way the idler jet still functions normally.

Go back a page or two. I mentioned the EFI kit and he said that he's convinced that a carb can work. The EFI kit is not a cheap endeavor, need a decent battery to keep it running and/or charging system.

Sent from my SAMSUNG-SM-G935A using Tapatalk

 

[bob58o]

Not much of an update.
SiliconeIntakes.com has accepted their mistake and they are sending me the 1.875" - 1.375" Silicone Reducer I need to attached the carb to the blower intake.


Looking into pulleys to drive the blower.
If it is 3.25" OD on the blower, then working Diameter for a type A belt is around 3"

A 2.05" OD pulley will have a 1.8" working Diameter.
A 2.25" OD pulley will have a 2.0" working Diameter.

3" / 1.8" = 1.67
300cc / 1.67 = 180cc per Revolution if 100% efficient.
360cc per 2 crank revolutions
360cc / 212cc = 1.7
1.7 * 14.7 psi = 25 psi
25 psi - 14.7 psi =
10 psi boost if 100% efficient.
If engine speed is 4000 - 8000 RPM, then Blower speed is 2400 RPM - 4800 RPM.
If engine speed is 3000 - 6000, blower speed is 1800 - 3600 RPM.

3" / 2" = 1.50
300cc/ 1.50 = 200cc per Revolution if 100% efficient.
400cc per 2 crank revolutions.
400cc / 212cc = 1.89
1.89 * 14.7 psi = 28 psi
28 psi - 14.7 psi =
13 psi boost if blower is 100% efficient.
If engine speed is 4000 - 8000 RPM, Blower speed is 2665 - 5330 RPM.
If engine speed is 3000 - 6000, Blower is 2000 - 4000 RPM.

If the blower is only pumping out 90% of what is should be (due to leaks at low speeds, or inefficiencies) the I think the 2.25" pulley will give me closer to 10 psi (instead of the 13psi theoretical).

If the blower is only pumping out 75% of the 300cc's around 2500 -5000 blower RPM, then I would probably want a 2.75" Pulley.

I think a Naturally Aspirated engine with static compression of 8.5:1 will have an effective compression ratio of around 14:1 with around 10 psi of boost. I'm guessing the blower should be most efficient around 2000 - 6000 RPM??? Not too slow to leak much, not too fast to over heat.

Maybe the 2.05" Pulley will be a good starting pulley for first testing. Clutch engaging around 3200 RPM will have the blower spinning around 2000 RPM at clutch engagement. And if engine top speed is 7500 RPM, then blower top speed is 4500 RPM. If I can get close to 300cc/ rev at 2000 - 4500 blower RPM, then I will be perfectly happy with the 10 psi boost and 2.05" pulley. If not getting 10 psi, I can try the 2.25"

 

[bob58o]

Wondering if that blower uses an alternator pulley.
17mm shaft? 17mm bore pulley? Or maybe 5/8"

Here's a 17mm Bore, #40, 20T sprocket to replace the pulley.
https://www.phidgets.com/?tier=3&catid=43&pcid=36&prodid=800

Here's the same with 5/8" Bore
https://www.ebay.com/itm/171565-Old...d=182777159117&_trksid=p2047675.c100011.m1850

Here's a 3/4" Bore, #40, 12T sprocket to place on the crank.
https://www.ebay.com/itm/40B12H-3-4...218871?hash=item33b17ef237:g:xucAAOSwB4NWvHoz

20:12 =
1.67 :1

Chain Driver Supercharger??? No belt slip.
Probably not enough shaft length?

 

[mckutzy]

Chain drive supercharger... Comming up....