Supercharges vs. Engine size.

[RomanV]

Besides which most times when you are at 100% effort you are traction limited, not power limited, and that midrange torque can be a hindrance not a help.

So an NA that weighs considerably less, with equivilent HP but less torque, would be a more appropriate choice of vehicle?

just stirring.

[fivebob]

So an NA that weighs considerably less, with equivilent HP but less torque, would be a more appropriate choice of vehicle?

In some cases yes, but only in the corners. Unfortunately real life road have straight bits so you end up being a mobile chicane (unless you have a F1 car )

[fivebob]

just stirring.

So we should just call you brown arm then

[Stealer Of Souls]

twincharging = waste of time IMO. Interesting from an engineering standpoint, but what's the point? What form of racing do you require power from idle to redline so bad that you can afford to add lots of extra weight and other parts to break?

Who said we're limiting the discussion to racing.
Street use would be the place for twincharge...
But too true. Twincharge is really interesting from an engineering point of view, but not to useful in real life...

super and turbo would be nice... super to fill in the bottom to 4k, turbo kicking in at ~3k, I think I'd like that.
Surely it is only a matter of tuning?

Sort of. It becomes a bit complicated when you want the SC and TC to produce different boost levels. Especially if they both use quite different boost levels.

[drftnmaz]

something i've always wondered was if if you had a twin charged car, seeing as the supercharger is producing much earlyier than the turbo wouldn't the sir just be pushed back past the turbo turbine?

or do you have to run them in series but then if you did that would the supercharger let 14psi throught it?


or am i looking at this the wrong way altogeather?

[RomanV]

So an NA that weighs considerably less, with equivilent HP but less torque, would be a more appropriate choice of vehicle?

In some cases yes, but only in the corners. Unfortunately real life road have straight bits so you end up being a mobile chicane (unless you have a F1 car )

Yeah, I know.
I like NA motors, but unlike many other NA afficinados, I concede that a 3sgte is... just plain better, in most situations.
So why do I like NA engines? I'll get back to you on that.

just stirring.

So we should just call you brown arm then

Well... no.
They say that “He who sups with the devil should have a long spoon”

But I say:
"He who stirs shit should have a long stick"

So no 'brown arm' here.

[Stealer Of Souls]

something i've always wondered was if if you had a twin charged car, seeing as the supercharger is producing much earlyier than the turbo wouldn't the sir just be pushed back past the turbo turbine?
or do you have to run them in series but then if you did that would the supercharger let 14psi throught it?
or am i looking at this the wrong way altogeather?

I figure there are about three valid combinations of twincharge...
SC -> TC -> Inlet... In this case you will also need a one-way air valve across the SC as the TC is almost certain to require more air than it can suck through the SC... Shut off SC when not in use.

TC -> SC -> Inlet... Ummm worst setup? I think this one needs a one-way air valve around the SC to allow TC to push enough air past the SC. Leave SC running all the time or shut it off, but if you shut it off one-way valve must be large one...

SC & TC in parallel... I think this is the best "technical" answer... But we'll see what happens when I put mine together. One-way valve (big sucka) on outlet of each charger prevents air from going backward through whichever one isn't runnning. Lowest inlet restrictions (heck, don't even know if this matters!). Can have individual filters. Could in theory run both chargers at the same time so that TC will run a reduced load...

[drftnmaz]

i didn't know you could get big arse one way valves cause i'd deff have them in parrallel if i could.

what are the valves off? and more importantly how much are they?

i've been thinking bout twin charging a car for drifing quite a bit latley.

[barryogen]

super and turbo would be nice... super to fill in the bottom to 4k, turbo kicking in at ~3k, I think I'd like that.
Surely it is only a matter of tuning?

Sort of. It becomes a bit complicated when you want the SC and TC to produce different boost levels. Especially if they both use quite different boost levels.

I was thinking more along the lines of the SC there you have full boost at 1000RPM trailing off to less at high end, coupled with a turbo that spools up fairly low, giving peak at redline... so essencially sitting on full boost for the whole rev range(within reason )

[Ako]

I think there's a few people in this thread who need to try driving a properly setup turbo engine - ditto for vice-versa.

The one s/c levin I have driven just felt n/a, which is the idea I guess, was nowhere near as FUN to drive. There's something about that tiny little wait for a turbo to kick in which is incredibly addictive, its the reason I stick with them instead of just going for a nice big V8.


And I still don't get the fascination with wanting power below 3000 rpm - what the hell would you do with it?? Even if you're making boost, you still won't be making worthwhile power. My VR4 made 18psi by 3200, doesn't mean it was fast there though

[Malcolm]

big arse one way valve = AFM
doesn't even need to be (electrically) hooked up, just plumbed in to each parallel branch of the inlet system.

I think the hardest part of a twincharge set up is getting it to behave well in transient conditions, could make it quite awful to drive if you have big surges at partial throttle while bits open and close, SC clutch engages and disengages etc.

[Adamal]

And I still don't get the fascination with wanting power below 3000 rpm - what the hell would you do with it?? Even if you're making boost, you still won't be making worthwhile power. My VR4 made 18psi by 3200, doesn't mean it was fast there though

3000RPPM if you're talking about a WIMPY turbo setup! A powerful turbo setup, you're looking at 3800+RPM with some lack below while the turbo absorbs power whilst spooling!

I drive quite often around the 2500RPM mark whilst daily driving, so to be able to have boost on tap would be fantastic. I wouldn't go for a roots type though, as they become too much of a burden at higher RPM. Twin screw is where its AT.
A) Each rotor is about half the diametre of a roots type, meaning theres less rotational interia to suck up crank energy
B) They do internal compressing withing the screws unlike a roots type, which only creates pressure by pumping air against the intake side (whilst valves are closed)

BLAH BLAH BLAH I'M DRUNK! (Or getting there)

Go the Twin Screw!!!! (Get your mind out of the gutter, I'm talking about superchargers here)

[Adamal]

I think the hardest part of a twincharge set up is getting it to behave well in transient conditions, could make it quite awful to drive if you have big surges at partial throttle while bits open and close, SC clutch engages and disengages etc.

From what I recall, Matt Dunn is the one and only person on here to experiement with twin charging, and made stupid ammounts of pressure. 30 psi at 1000RPM.
If it were easy to do, it would be fantastic. The supercharger would forcew more air in there, meaning that there would be more exhaust gasses coming out, meaning that the turbo would spool faster. Huge ammounts of flow through out the whole rev range. It'd be the ultimate in forced induction.
Problem is, its a lot of work and money to get right. And when you're talking like 30psi at 1000RPM (example), thats a hell of a lot of pressure once the turbo starts doing its part. Engine rebuilt after short ammounts of time

(Posted shortly after above post. Please take alcohol into consideration)

[fivebob]

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(Posted shortly after above post. Please take alcohol into consideration)

Really, couldn't tell, maybe you're not as thunk as you drink you are

[Adamal]

Fivebob for Toyspeed legend!!!!

Yes, just for that. I'm grinning from ear to ear

[KE20]

its a CAT turbo, i have know idea of trim etc, but it huge.

[BZG Wagon]

Supercharges are quite impressive, but im not so keen on the idea of using power to make power; which I why I like turbos - using waste to create power.

This is all in a very simplistic sense of course.

[dash]

there must be some merit in supercharging, as the miatas have the biggest sample of various add-on turbo and supercharger setups I've seen, and after all these years they're still doing both.

One particular built 1.8L with custom brackets and pulleys dyno'd an amazing 340hp at the wheels, with an unusually high 310 ft-lbs tq. Done via an overdriven eaton m62 blower. Turbo miata owners, who went for a ride during a miata meet, all pee'd their pants claiming nothing quite matched the instant response & "huge motor like" pull of this beast.
Makes all the difference if done correctly, eh.

On twincharging, there used to be a very popular site featuring a white aw11 with a modified version of the hks tc kit. Car ran a decent mid 11s 1/4...but... as reviewed by a popular magazine editor, from just above idle the substantial, ever increaseing thrust felt like the "seatback was trying to leave a fabric imprint on your kidney". Hes perhaps tested alot more turbo cars than any of us ever will, and to comment on how unusual the power delievery was, says volumes. Incredible if you accepted a mere 1.6L produced it

Instead being consumed by 'theory', they built unique machines

[The Game]

why or why not would it be gay to turbo my 4afe

[GGnz]

Slightly off-topic or maybe on (kinda jumped the thread abit) but I wanna turbo my NA 20V Blacktop. Whats involved in it? ($ aint a prob). Even if anyone knows a link or thread they could redirect me to? Cheers