49 replies to this topic

[D-Train]

Right. Thanks Garth. I was thinking a 186. I heard the sc12 would be pretty weak, but would it give anything for low revs until a turbo kicked in?
While we are talking blocks, what would be the best engine size to use for strength when it is going to be boosted.
I was maybe going to fit small supercharger and turbo with low boost so I don't have to do much to the engine, just to get the fundamentals of a twin harge system sorted. Then once it all works do it properly with something a bit bigger.

[EunUCh]

I think there will be some "number crunching " involved,Garret offer a list of Turbo's with "maps" of where the best islands are for a particular turbo.

 

With 2 of them ,a small one for "primary boost" to reduce lag would be nice and then have the "bigger" one kick in once things are up to speed,who knows how you would go about "compound boost" from a twin  turbo set up but there should be some-one that knows.

 

Heat will be a problem,might need an inter-cooler the size of a Mack truck radiator?

 

The beauty about an engine driven super charger air pump is that lag is minimal and even though adiabatic compression is still present the Norman style pump seems to be able to overcome this to a degree?

 

From what i found out the SC 14 is max 14000 ,and that is probably pushing it,some say 12000 for a bit of reliability?

They were from what i understand  bolted to low capacity 4 cylinder engines and were slightly "under driven"?

 

Some people say that a super charger should be capable of pumping half the cubic capacity of the engine?

SC14 is 1.4L/revolution,double that, and that is the engine size it would be suited to at 2:1 overdrive,a 186 would just make it? 

 

 

[UCgazman]

Post #15...

 

By your numbers an sc14 at 2:1 o/d will pump 2.8lt per rev. Meaning it would suit up to a 5.6lt engine? I'm telling you from experience they are ok with a smaller pulley on a 3.8lt commo, but nothing bigger.

[D-Train]

Yeah I checked out the Garrett sight and they have some great graphs that show spool up time and max boost etc. It just a matter of pairing the right sc do there's no major drop or surge in between. Also depending on delivery of the combination.

[orangeLJ]

Look at the hks twincharge kits for some.inspiration

[FLY_LX]

Im no expert but I looked into this a while ago.

 

First thing is with compound boost it is a higher than it seems. i cant remember the exact formula but for example if you have 8psi boost from your turbo and another 8 psi from blower that would be about 20psi not 16. it goes by a factor of 1.5 or something?  

 

Second is the complexity in bypassing the supercharger and the switch over point, you don't want to have a big hole in your power waiting for the boost to get back up.

 

Obviously you can run a much bigger turbo than you normally could.

 

You can either run the supercharger through the turbo (hks, vw ) or you can do it the other way run the turbo through the supercharger (Lancia delta).

supercharger through the turbo is probably going to be easiest to set up.

But strange as it may seem running the turbo through the supercharger is actually a better setup for power, because you increase the efficiency of the supercharger. Group b lancia deltas ran 1800 4cyl making over 600hp with that setup.

 

I suggest you look into the setup of the lancia engine. Also a good book to get is "Maximum Boost" by Corky Bell it tell you everything you want to know. 

[D-Train]

Thanks fly Lx and Orange lj. I am still to look at the Lancier delta and the book max boost, but just commodores has a good thread. Unfortunately it's all about the vee boys but It should transfer to straight sixes.
So far I'm thinking air filter-turbo-supercharger-ic(either air to air or water to air, undecided)-manifold. Have a computer so once the sc boost equals the turbo boost, the sc clutch is disengaged and a valve opens bypassing the sc. this seems to be the best way to keep a fairly linear power curve. If I was to compound the turbo boost through the sc the whole time it would be a big kick when it spooled up like a standard turbo car.
This is what I have so far. Anyone else got anything too add or subtract. Be brutal.

[D-Train]

i think I know what you mean, but I was thinking of say for eg sc 6 psi and turbo 10 psi, so when the turbo reached 6 it would take over and spin up to 10. Also with the sc off it will stop any parasitic losses caused by spinning which should give a bit more gain at that point. Does this work?
Until I do it its just a bit of a guessing game for me with experience chucked in by you blokes. I really appreciate the feedback.

[D-Train]

i think I know what you mean, but I was thinking of say for eg sc 6 psi and turbo 10 psi, so when the turbo reached 6 it would take over and spin up to 10. Also with the sc off it will stop any parasitic losses caused by spinning which should give a bit more gain at that point. Does this work?
Until I do it its just a bit of a guessing game for me with experience chucked in by you blokes. I really appreciate the feedback.

[D-Train]

Before I possibly destroy my nicely built 186, I'm going to buy a stock 186 and make this setup with a small sc and turbo so I can do all the trouble shooting and if it shits itself, no biggy. So I will want to do this out of the car for ease of building, so I have two questions.
1) can I use a normal engine stand to build and run an engine. If not what can I use, or do I need to make a bench kind of jig myself.
2) is there some kind of equipment I can buy that will give me a hp figure with the engine out of the car. I know engine builders have equipment to do it, so if anyone could give me any info, that would be awesome.
I have an LM-2 which will give me some handy info. I just feel that I need original hp figures as a base point then final hp to see if this project will be worth moving onto my real car.

[Uncle Chop Chop]

If you had access to an old HQ ute or van chassis, that would be a more stable way of testing it.

[FLY_LX]

Due to the way they work a supercharger running at x rpm to generate y boost wont "compound" the boost from a turbocharger making the same y boost. It cant happen. 

Ridiculous Bomber. if i run compressed air from a turbo into a supercharger that air will be compressed further (compounded). doesn't matter what speed it runs at supercharger moves a fixed volume of air per revolution

 

Vic i don't know if you have your hardware yet but i would consider using an eaton supercharger either from the commodore (m90) or mercedes (m62)  they also have built in bypass valves, and running a old t04 through one of them. all cheap and plentiful

 

the m90 recommended sustained max revs are 12000 and the m62 14000 run @ 2:1 ratio gives you a 6000rpm limit which is ringing a red 6. i would also lower your CR to 7 something but not with a decomp plate. then you dont have to worry about any switch piont would be easier to setup and tune.  

 

i can hear bombers keyboard working a response . From my understanding and im no expert how this works:

running turbo > supercharger > engine

the supercharger increases the air consumption of engine = more exhaust gas = turbo spooling up quicker = more efficiency

turbo into supercharger  = increased supercharger efficiency (no back flow) = more boost

 

running supercharger > turbo > engine

the supercharger increases the air consumption of engine = more exhaust gas = turbo spooling up quicker (but will have back flow in blower)

turbo becomes an obstruction in a way because the air from the blower has to turn the turbo compressor (Cold side) and the turbine (hot side) then into engine, until it builds up enough speed to compress the air its self. so all you are doing is forcing the turbo to spin before it wants to. you also need to bypass the blower or that becomes a restriction for the turbo when switch to turbo alone.

 

Just my 2c but good luck how ever you do it

[D-Train]

I've got the compound boost maths sorted. Its multiplied, not added, as was stated earlier. For example(rough figures for ease of example). Running a sc at 7 psi is 1.5 bar. Turbo at 15 psi is 2.0. So it's 1.5 x 2.0 = 3.0. Which equals 29.4 psi not the addition at 22 psi. Hope this is correct. Correct me if I'm wrong.

I have a sc12 and a td04 off a forester. I know they are both baby boosters, but for testing I hope they will tell me what I need to know. I may still get a m90 as fly Lx recomended but see what happens. All I need now is a 186 and a mig. Tossing up wether to buy new or second hand with the welder. Any recommendations?

With centrifugal sc, are they instant like roots, lobes and screws, or do they require a small amount of build up?

[D-Train]

I also looked into DIY dyno. Looking at about a thousand for an engine inertia type through dyntec. It comes with software sensors etc. although I need to source my own flywheel, connections and frame. I might get an old ute as Vick said, and then check the hp through my g tech pro. I know it won't be exact, but they are fairly close according to some people testing them on u tube.

[FLY_LX]

http://www.hotrod.co...charged-engine/

[FLY_LX]

forester turbo is petty small, i think factory wastegate is about 6-7psi and run out of puff about 5500rpm on a 2ltr, so i don't think it will do much on a 3ltr. you can try it and see what happens, but when you get over 15psi your boost will start to fall off in the top end as your on the wrong side of the compressor map.

 

i bought a small mig years ago for $100 not the best but it runs on gas and it welds ok as long as steel not to thick, and duty cycle terrible at full power. I bought for rust repairs so it does the job.

Shop around or i think there's a post on here somewhere about welders.

[Uncle Chop Chop]

US $160K for an engine? I'm not that keen.

[D-Train]

Thanks fly Lx. That engine is the setup I was planning, minus about 2000hp, but at least I know I'm on the right track.

I agree, but I read today there is a controller you can put between the boost sensor and wastegate to control what psi the wwastegate opens at, or does this not matter due to the small size. But at the same time, I have a tiny sc too, so even though I won't get full rpm with the small combo, it will still allow me to work out the changeover point, bypass valves etc before I start playing with the real stuff and spending big cash. To start with,

I suppose I could do this on a four banger for my tests, but I want to do it with the red six so I can learn everything I can about these engines.

[D-Train]

What if I used a little 138. Are they all similar except I'm guessing bore and stroke?

[D-Train]

Exactly what I am planning to do. Sounds good. Thanks for the heads up Peter. Still haven't found anyone on the net that has done it to a red six. Surely it's been done, but I'm happy to be the first.