Forced induction 100cc

[Grumph]

The blower is going to get HOT...ours on Meth (which had quite an effect on mixture temp) got too hot to touch...
An air to air intercooler IMO won't be good enough unless very big. It's a bucket hence airflow through any cooling system is going to be a problem whatever you do. Clearances must allow the blower to turn freely when very hot even if it loses boost as result.
Temperature is going to be your limiting factor everywhere - boost and compression ratio will be critical. I don't even like the thought of running 2T oil in the fuel as it may be enough to cause deto. Toluene is your friend...in avgas, mixed away from the track and brought along in a plain can.

[Yow Ling]

you cant put an intercooler on a drawthrough system

[Sketchy_Racer]

The blower is going to get HOT...ours on Meth (which had quite an effect on mixture temp) got too hot to touch...
An air to air intercooler IMO won't be good enough unless very big. It's a bucket hence airflow through any cooling system is going to be a problem whatever you do. Clearances must allow the blower to turn freely when very hot even if it loses boost as result.
Temperature is going to be your limiting factor everywhere - boost and compression ratio will be critical. I don't even like the thought of running 2T oil in the fuel as it may be enough to cause deto. Toluene is your friend...in avgas, mixed away from the track and brought along in a plain can.

Yes I think you are right and as Yow Ling below says I probably wont be able to run a intercooler through a draw through system because of fuel dropout issues. I might have to design a water to air system that makes sure there is not possibility of fuel drop out.

you cant put an intercooler on a drawthrough system

Yep, completely overlooked that issues.
I guess it's back to solid works to design a water to air style that incorporates the plenum and pop-off valve into it.

I'll post what I come up with and see what you all think.

[ducatilover]

Surely a draw through on a blower that small will keep itself cool enough? Otherwise you could set up meth injection to the rotors?

[Kickaha]

What about a water injection system?

[Sketchy_Racer]

Surely a draw through on a blower that small will keep itself cool enough? Otherwise you could set up meth injection to the rotors?

Depends on the supercharge efficiency. it's a bit hard to calculate on paper how efficient it will be so will have to wait until I get it finished. I was going to have a look at calculating the expected temperature rise if the blower was 100% efficient but I don't have enough information about the setup yet, and the equation would take me a little bit to figure out.

Either way a turbo charger on car running at around 80% efficiency will easily see intake air temps of 80 - 100 degrees before a intercooler, so getting rid of that heat is going to be rather important.

[bogan]

Yes I think you are right and as Yow Ling below says I probably wont be able to run a intercooler through a draw through system because of fuel dropout issues. I might have to design a water to air system that makes sure there is not possibility of fuel drop out.



Yep, completely overlooked that issues.
I guess it's back to solid works to design a water to air style that incorporates the plenum and pop-off valve into it.

I'll post what I come up with and see what you all think.

Maybe time to step back a bit, and re-evaluate FI and standard intercooler? Just seems like there is talk of a lot of build work to get it running with carbs, when FI offers tuning advantages, and it doesn't sound that hard to do...

[Sketchy_Racer]

What about a water injection system?

Weight would be the killer . The pump size to get enough pressure to atomize the water well enough will be to big and also draw to much current.

Not to mention carrying an extra tank of water.

I run water injection on my diesel tow wagon and although I only monitor exhaust temp gas with just water I see about a 50 degree drop and with methanol 50/50 mix I see 100 degree drop with probably 20% power increase.

[Sketchy_Racer]

Maybe time to step back a bit, and re-evaluate FI and standard intercooler? Just seems like there is talk of a lot of build work to get it running with carbs, when FI offers tuning advantages, and it doesn't sound that hard to do...

Yes this is true, I could look at stealing the fuel system of a late model 250 MX bike with FI would be easy to get.

However running a draw through system does have it's advantages in terms of helping the supercharger efficiency

From the elsberg tuning site

Running mixture through the supercharger does have several advantages, as it "seals" the rotors at ends and tips, making it pump more efficiently, and another bonus is a reduction in the charge- temperature. And I have to mention that I in several cases have seen an increased mileage in no- boost situations, when running the blower "wet", which leads me to think that the whirling rotors have an effect too, as they "atomize" the charge into smaller particles.

[bogan]

As long as the lower efficiency of blow through is more than balanced out by lower temps (therefore higher power), it's still a better option isn't it?

[Yow Ling]

Depends on the supercharge efficiency. it's a bit hard to calculate on paper how efficient it will be so will have to wait until I get it finished. I was going to have a look at calculating the expected temperature rise if the blower was 100% efficient but I don't have enough information about the setup yet, and the equation would take me a little bit to figure out.

Either way a turbo charger on car running at around 80% efficiency will easily see intake air temps of 80 - 100 degrees before a intercooler, so getting rid of that heat is going to be rather important.

My book says a shorrock supercharger is 65 to 70% efficient and a roots blower is less, because efficiency will drop even further as the scale goes down, the temp rise may be a bigger problem
The book is Turbocharging and Supercharging by Alan Allard, ISBN 0-85059-494-4 was printed in 1982 so most of it is relavent to this project

[Yow Ling]

some links in here
http://motorbicycling.com/showthread.php?t=25023

[Yow Ling]

this is pretty small intercooler, for scale the drainpipe is 75mm
has quite a large volume in the end tanks. I was going to put it on my Fiat 500, its off some 500 or 600cc jap import

[pete376403]

Weight would be the killer . The pump size to get enough pressure to atomize the water well enough will be to big and also draw to much current. .

A water injection system I made for a turbo (car) used a windscreen washer tank and pump squirting into the turbo inlet through (pretty small) carburettor jet - although atomisation wasn't really an issue because as soon as the water stream hit the compressor wheel it was pretty well vapourised. Did the job, though

[jonbuoy]

If your only running moderate levels of boost how much of a difference is an air to air charge cooler going to make especially at lower speeds? You could water jacket the supercharger itself if its just running temps your worries about, there is a weld on kit for my eaton that puts a water jacket over the plenum with a circulating pump and a wee radiator.