Turbo vs Supercharger

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MAT713
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Post by MAT713 »

not a gemini, but I've owned a couple AE86's and driven plenty

my last one had a 4A-GZE, it was fairly stock, just an exhaust, FMIC, CAI and a couple pound more boost from blocking the air bleed valve.

it made just a smidge over 200rwhp, and this thing went like a frickin rockt!! loved every bit of it.

after driver a similar engine, but with forged internals, cams and head work plus a t28 turbo with a bar of boost the thing also went really hard, making something closer to 250rwhp,

now the turbo spool up really felt fast and it was, however, I still managed to pull away cuz i was making reasonable power from 1200rpm! the turbo had its usual lag, finally 2 gears later i was over taken.


driving the 2 and comparing, my personal choice, was to sacrifice i tiny bit of top end and gain a s*#t loud of low-mid torque espeically for street car or hill climbs
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MAT713
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Post by MAT713 »

on another note, i dont know how many ppl use the SC-14 blowers on the 'g' series motors, but they do go unreal on thr 4A toyota range.

u can pick these things up for like 150 bucks, the bigger SC14 (off a 1G-GTE) will handle boost a lot better then the SC12 (off a 4A-GZE)

so mount them up, a bar of boost and the right tune these things would crank on a 1600cc
= FOR SALE = Mazda RX-7 S6 13b TWIN TURBO set up - VGC, Low KM's, Everything Included
= FOR SALE = Mazda RX-7 S6 FRONT X-MEMBER - Including Upper / Lower Control Arms & Hubs
Pricey
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Post by Pricey »

GRAH too much info my head is imploding! :shock:

As a daily, what option would be more fuel efficient? Or MORE LIKELY to be fuel efficent?

My noob sensors predict that turbs will be more as you can play with boost and/or just shift before you hit boost, whereas sc will always boost... but I want confirmation.
lukes_tg
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Post by lukes_tg »

although you can buy a supercharger that you can turn on or off. and yer a supercharger loses power because it is spun by the crank but it also gains ashitload more to. and althought turbos can lag and superchargers wont id still go a turbo anyday, also sucking?? bov??
Gemi Coupe
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Post by Gemi Coupe »

post contents removed
Last edited by Gemi Coupe on Tue Oct 26, 2010 8:56 am, edited 1 time in total.
lynn1221
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Post by lynn1221 »

I agree with what the previous two people have said, but will add one more comment. The downside with a supercharger is that it robs the engine of a lot of power. I agree with what the previous two people have said, but will add one more comment. The downside with a supercharger is that it robs the engine of a lot of power. The turbo takes a lot less power, comparatively, to run. Although the turbo runs on the exhaust gases, it adds back pressure to the exhaust system and therefore restricts the horsepower. However, this effect is much smaller than the benefit gained by boosting the pressure of the intake air.The turbo takes a lot less power, comparatively, to run. Although the turbo runs on the exhaust gases, it adds back pressure to the exhaust system and therefore restricts the horsepower. However, this effect is much smaller than the benefit gained by boosting the pressure of the intake air.
jassoo
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Post by jassoo »

RIX wrote:turbos are more prone to detonation than superchargers!
Away from the topic but that wuold have to be one of the funniest & coolest avatars i have seen good work
cars...
TE V8 project
TX 161 injected turbo
hilux dual cab 2wd
luvtheG180
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Post by luvtheG180 »

has anyone on the forum put an sc-14 or similar supercharger on a g180? that would be a pretty simple swap if they run decent.
luvtheG180
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Post by luvtheG180 »

currently shopping for a supercharger for my G180.
the engine is freshly rebuilt including new head and block, new bearings, all properly assembled and broken in. running a 4x4 chevrolet LUV i am very limited on compatible engine swaps. so im planning to go with low boost from 6-10 psi.

my questions are.
how durable is the SC14 series supercharger for a daily driver application?

what is the best placement for the clutch for a balance of power and reliability to avoid overheating and damaging the supercharger.
mistareno
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Post by mistareno »

There is alot of good info and some alarming misinformation in this thread. There are pros and cons to both, but some of them are not immediately obvious.

Turbo.

An internal combustion engine is not a very efficient device. It's power output (from the fuel burnt) can generally be broken down into 3 paths.

1/3 power goes to the wheels,

1/3 goes into the cooling system as heat.

1/3 goes into the exhaust as heat.

The turbo utilises that last 1/3 of wasted energy by routing the otherwise wasted expanding and fast moving exhaust gasses in the exhaust to spin a turbine that in turn spins a compressor.

The turbo is nothing more than a centrifugal air pump which by it's nature has greater volumetric efficiency than any roots type compressor (Eaton/Toyota)

A centrifugal pump by virtue of its better VE will add less temperature to the air for a given boost pressure than a roots type compressor - period.


Any increase in temperature experienced by a turbo system over a supercharger system is due to poor thermal management or poor turbo selection, not through the fault of the turbo itself.

The compressor side of the turbo should be thermally shielded as much as possible from the hot turbine side.

The easiest way to do this is to thermally coat the exhaust manifold, turbine housing and dump pipe. Turbo blankets are another good option. I would rate thermal management as one of the most important aspects of a turbo charged car.

Sound thermal management will have a two fold benefit. It keeps the heat inside the pipes (which increases turbo efficiency and boost threshold) and it reduces underbonnet temperatures, which increases overall system efficiency as the lower the turbo intake temperature, the lower the turbo output temperature.

Another common mistake (for want of a better word) is using a turbo that is too small in a bid to remove turbo lag.

Turbo lag is often confused with boost threshold and whilst the driver may perceive them as the same thing, they are in fact different.

If you ran a large t3 turbo on 1600cc engine, the engine wouldn't generate enough exhaust flow output to spin the turbo into useful positive boost until 4000 rpm or so.

That is not turbo lag. That is the boost threshold. It is a set parameter.

You would stand on the gas and get N/A performance until 4000rpm and then the boost would rise. You might be get max boost at 4500rpm but are left with a small power band.

Lag is when the engine is within the its boost production range and you have to get off the throttle (for a mid corner adjustment or similar) and then when you reapply the throttle (still within the boost production rev range) you experience a momentary lag as the turbo tries to spin up again and recompress the intake charge.

There are 4 main things that affect lag.
- Turbo design.
- Excessive piping and intercooler volume.
- Poor BOV location or function
- Wastgate turbulence

A turbo's lag can be affected by its inertia and it's bearings.

A well sized modern lightweight low inertia turbo will spin up faster than a heavier older one or one that is oversized and a ball bering turbo will spin up slightly faster than a journal bearing one.

Having a massive front mount cooler on a 1600cc car that only sees 10psi is pointless as the turbo has to compress all of the intake volume before the engine sees that level of boost. Rather stupid if you want a driveable car, perhaps ok on a drag car. Having massive piping on a 1600cc engine is stupid - period (unless you intend running mega boost)

Venting a BOV to atmosphere is both illegal (on the road) and wasteful, as the vented BOV air can be re inserted into the pre turno air intake to help energise the airflow into the turbo which reduced the compressors spin down.

The flow from a wastegate (particualrly the integreted type) should be seperated from the main turbine exhaust as much as possible and merged into the exhaust flow further down the dump pipe (or even further down the system). Some cars even run a seperate 'screamer' pipe to the back of the car.

Excessive exhaust back pressure is another common complaint about turbo systems but is - again - usually the result of a poor turbo choice. A turbo will always add some back pressure to the exhaust. If it didn't, it wouldn't work.

The problem is when a turbo that is too small is installed. It will give a very low boost threshold, but will excessively restrict exhaust back pressure and reduce the overall performance of the system as the turbo will fall off it's efficency curve (resulting in higher intake temperatures) as the revs rise. Do you really want a turbo diesel style power delivery?

As a rough guide, you should aim for the turbo to be producing useful boost by 1/3 of the redline.

In short, a well designed Turbo installation will always be more efficient than a Supercharged car of similar power - particularly the Roots.
Last edited by mistareno on Wed Mar 02, 2011 3:18 pm, edited 1 time in total.
Buggzy
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Post by Buggzy »

nice write up... thansk a learnt a bit myself.

one thign i have learnt in my experience is that both super chargers and turbo's when used correctly, setup, tuned and matched with engine and specs, both are awsome to drive and make good power.
Boostin for lyfe!
saif003
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Post by saif003 »

For those structure their own kit I would praise always deed to a supercharger 1 filler above what the engine susceptibility suggests, as the soprano for the incoming situation higher is quite teensy and if needed put a restrictor in to minify the hike. The ground I say this is that most people line off with quite retiring expectations but as presently as they change it fitted they requisite MORE and if the supercharger they get already fitted is travel at max power, they individual to toss it and buy a realized new supercharger organisation.
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