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Discussion Starter #1
hey guys, i have a 1985 alfa33 1.5 8v, carb'd of course. i went out and bought myself a supercharger. its gonna be a nice project to see how this thing will go. so the supercharger is a toyota SC-14 which came out of a 1G-GZE. i still want to run the 2 twin carbs. this supercharger is capable of puming 12psi if not more.

what do you think will be more efficient/ better??? i either put the supercharger on top of the 2 twin carbs so then it will be a blow through. or i can put the 2 twin carbs on top of the charger, therefore making it a suck through......
I know that making it a blow through will be much easier but that puts strain on the carbs....

cheers guys.
 

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In a few words... A fair bit.

If you search the forums there's a few other threads about forced induction that might give you an idea.

I think one is the turbo boxer thread, and the other is the supercharged one..


lenus.
 

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Discussion Starter #6
ok, yea ive had a look at those threads, but the turbocharged boxxer is injected, and so is the supercharged one. so is it possible to use the standard 36mm down draft webbers? if i want to sit the charger on top? if not then can i sit the carbies on top of the charger and have it a suck through??

thanks for your help anyways.
Lucas
 

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That thread also talks about the benefits of superchargers and turbos.

The benefit isn't much. You also have to look at making custom manifolds and stuff for the supercharger, so it even ends up costing a bit of dosh. When you could just be buying a 1.7 16v engine.


However, it should be possible to use the down draft webers ontop of a supercharger.
 

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Discussion Starter #8
hm... well thats one option, the other option was what you mentioned, sitting the carbs ontop of the charger, which is what i was primarily going to do, i just wanted to know if having it the other way would have any kind of benefit, it also sounded a little bit easier. ok so now that ill be sitting the carbs ontop of the charger, i need to frigure out a way to distribute the air/fuel equally..... thats after the charger of course.
 

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As we can see in the above post of the charged sud it is using a single carb manifold which for the blower is one option the other is to use IE and its related manifolds.
 

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Carb'ed turbo/supercharged cars are horrible for street use. I don't know why you'd want to go there. Unless you are developing max HP for drags.

Having said that, blow through setups are far better than suck through systems, which suffer from excessive lag. As Lenus said, carb mods will be necessary though.

I'm sure many people have built blow through super / turbo setups on Weber IDF carbs before. Why not browse on some VW or Porsche forums. Their owners tend to be much more adventurous than the majority of Alfa owners. :D
 

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I've spoken to a fellow who used a 1.5 twincarb motor as a base for his turbo project. As far as the inlet side goes, other than jetting, the only mod required to the carbs were better shaft seals. Otherwise he ran the turbo plumbing straight into the inlet horns.

Good idea, the SC14. I'm actually looking at an SC12 at the moment to fill the space left my my soon-to-be-removed airc compressor. Keep in mind the SC14 is physically much larger than the SC12 (as used on the MR2 & 4AGZE Corolla).
 

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Discussion Starter #13
thanks evilgidget.
about the SC-14 and the SC-12, ive noticed the size difference. i had a look at both but i got the SC14 for cheaper...
ive taken the AC compressor and now there is a massive empty bit... so i was thinking of putting it there... or i would move the altenator and fang the Sc-14 right on top of the block with custom piping running from the carbs(on very top) to the supercharger, then piping splitting the air/fuel mix straight into the engine....

the only thing is, i dont know what kind of pulley ratio i should run... if i should run the stock ratio or something a little different.


cheers
Lucas
 

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Hi, I am currently doing all the prep work for an all-steel supercharged 16v boxer, for my sprint/ hillclimb car. (I have already built/ am currently running an all-steel NA full race boxer).
Anyway, I have spoken to many "old-school" Alfa racers who have "been there, and done that"! They were all running a Sprintex with single carb. The problem ALL the time was fueling. -They just could not get enough into the **** thing!
Their advice to me was go injection for sure, with mappable ECU the fueling is no problem at all.
I know it all comes down to budget...........
I am sure you will have a lot of fun with your project, but as always, big power costs big money!
-I have had special low comp pistons made, have you thought about comp. ratio yet?
(You need around 8 to 8.5:1, and as for inlet pressure, you don't want more than 6 PSI really, as you start introducing more latent heat).
Last thing, you need to think about cooling a lot!!!!!!
-Not intercooling, but engine cooling. The thing is going to be getting about 1/3 hotter!
Hope this helps, best, Graham.
 

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I would agree with Graham's comments regarding force fuel induction to a boxer engine.
I had a turbo on a 1.5 motor and it was not a good result. It was set up as a blow through the cabys deal ( two 40idf) and this worked reasonable OK but at high revs the fuel would lean out and burn the pistons. When the jets were changed to richen up the mixture the engine wouldn't think about running at less than 2000RPM and still burnt pistons. I built two engines and they both only lasted 1500Kms. Thats why I agree with Graham that the set-up needs to use injection so that the mixture can be properly mapped.
A couple of other things to think about, the *** blowers are designed as blow through units for use with injection. If you try to put fuel through them they will hydraulic and cuase the impellors to seize. Have tried this method as well. Another issue to consider is that when the turbo/scharger is working you will see incredable torque steer. My car would jump about a meter to the left even in third gear, pretty awesom, but very dangerous on the road. On the track the car did suffer from increased heat build up.
I overcame alot of the torque steer problems by using rose joints in the front end. I know I am not painting a very rosey picture with regards to your proposed project, but I figured I should share some of my experiences with you before you sink truck loads of money into this thing. I not saying it cannot be done, but it will require quite a bit of money to pull it off. I would also suggest that you do as much research as you can before proceeded with the project. Unfortunately it is not the type of project that can under taken in stages. Good luck with it, it is unbeleiveable to drive ( in my case a Sprint) if you get it sorted.
 

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Discussion Starter #16
thanks alot for the advise guys, i havent started any mod or anything yet, im just trying to sus it all out first. if i can get my hands on a 1.7 16v injected ill grab it, but as for now i have 2 1.5 8v carb'd engines. both in working order, one is in the 33 that i drive now. and the other in the parts car which is exactly the same....
so i dono. but yea if i find a 1.7 engine for fair cheap ill grab it.
also i realized that the torque steer would be insane. i can feel torque steer now with my 33 wagon, but its only slight. and all thats been done to it is a new exhaust system and been lowered.


cheers
lucas
 
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