TECH TALK - ask your technical car questions

SomeKindOfMonster · Post by **SomeKindOfMonster** » 02 Nov 2006, 04:19

The latest craze in Australia at the moment is twin supercharger setups, that feature a centrifugal supercharger sucking the air in and compressing it, then feeding the already copressed air in the intake of a whipple (or roots) blower mounted on top of the manifold, giving insane power. Correctly doing this can give the same effect as using a twin turbo setup, but wihout as much space loss (which is a good thing when used with a V8)

darknight788 · Post by **darknight788** » 02 Nov 2006, 06:34

jeez that sounds crazy , about how much boost are those setups putting out. i know of some pickup trucks around here running twin-turbo setups and they put out around 60-70 psi which is alot for a truck

vanyots · Post by **vanyots** » 02 Nov 2006, 10:45

darknight788 wrote:jeez that sounds crazy , about how much boost are those setups putting out. i know of some pickup trucks around here running twin-turbo setups and they put out around 60-70 psi which is alot for a truck

That kind of boost is A LOT for anything but TopFuel Dragsters!
20 years ago in the Turbo era of Formula1 the best engines with quad-turbo boost had 4bar(less than 60psi) and reached 1200-1400HP@14000rpm from 1500cc engines...

Grez~Supra_RZ-S · Post by **Grez~Supra_RZ-S** » 02 Nov 2006, 12:47

I know a fair few street cars that run between 35-40PSI. IMO, 60/70 sounds reasonable for a truck given the amount of torque that they need.

SomeKindOfMonster · Post by **SomeKindOfMonster** » 02 Nov 2006, 22:32

Only around 40psi. Without lowering the compression ratio too far, 40psi has seen some aussie street cars crack 1500rwhp!! To run 80psi on a SUV, the compression ratio would have to be around 7.5 to one, otherwise the heads would lift off the block. I'm still trying to find a picture of a twin super-charger setup, but here is a pic of australia's first 1700rwhp family car (pictures don't do it justice, as the turbo's are hidden away under the intercooler piping. The air/water intercooler that runs right through the car to a big tub in the trunk cost around $125000 alone, and is capable of keeping the operating temps around 90degrees celcius, even when under full boost.

Grez~Supra_RZ-S · Post by **Grez~Supra_RZ-S** » 03 Nov 2006, 01:29

Of course, saying ''to run x amount of PSI on an SUV'' is all well and good, except that all engines in the SUV range are different. They will all respond differently to different boost levels.

I know of a 450bhp SX that runs 37PSI. In all honesty, its not an unbelievable amount of boost. The lag is horrendous mind you.

boganbusman · Post by **boganbusman** » 03 Nov 2006, 01:58

I've seen that Commodore in the flesh, it's pretty crazy. I didn't know it had a water/air cooler though, all I could see was the massize air/air cooler in the front.

I've taken a pic of the car with the front bumper off

nismodriftster95 · Post by **nismodriftster95** » 03 Nov 2006, 03:18

How does a turbo or supercharger work?

boganbusman · Post by **boganbusman** » 03 Nov 2006, 03:44

Here's a howstuffworks article on turbos:
http://auto.howstuffworks.com/turbo.htm

and superchargers:
http://auto.howstuffworks.com/supercharger.htm

Those articles should give you a basic understanding. If you want, you can ask for more technical information in here after reading them.
There is also some discussion about turbos and superchargers on the previous page.

SomeKindOfMonster · Post by **SomeKindOfMonster** » 03 Nov 2006, 04:24

The clubby runs piping from that intercooler to the boot, where there is a 120litre ice/water chest with 4 electric pumps in it. The hot air runs through piping under the body on the drivers side, and returns on the passenger side at abour a quarter of the temp. He managed to make 1800RWHP with the engine on fire when I was at summernats last year. As for running 37PSI in an SUV, that is definately believeable, but when you start talking about 60-70 PSI, the heads will lift, unless the compression ratio is insanely low, making it nearly impossible to drive until boost is reached.

darknight788 · Post by **darknight788** » 03 Nov 2006, 09:34

dont get me wrong these trucks are not your everyday this video shows the some of the trucks that run around here with TT setups making lots of boost, some even make 50 psi off of one turbo http://www.youtube.com/watch?v=W0WMKNK60Ck

steelsnake00 · Post by **steelsnake00** » 03 Nov 2006, 19:18

Direct Displacement Superchargers (AKA Twin Screw setups)
Does anyone know any UK builders of Twin Screw chargers? What kind of horsepower increase would you be looking at from ~9psi from a TS system on a ~360bhp engine?
----
Isn't a Roots type blower a centrifugal supercharger anyway? Or did you mean feeding into a Twin Screw charger?

boganbusman · Post by **boganbusman** » 04 Nov 2006, 03:05

Nah, a roots blower has big fat vanes inside it that mesh together, kinda similar to a screw-type blower. A centrifugal charger looks just like a turbocharger, minus the turbine housing.

SomeKindOfMonster · Post by **SomeKindOfMonster** » 05 Nov 2006, 08:19

Roots blowers are basically a screw-type blower with different "screws" in them, but are nearly identical. Centrifugal chargers are totally diffferent in shape and design

R34GTR · Post by **R34GTR** » 15 Nov 2006, 17:19

I can smack my starter motor with a hammer right? :p

Any other ways to get your starter motor working without replacing it/beating it with a hammer.

Grez~Supra_RZ-S · Post by **Grez~Supra_RZ-S** » 16 Nov 2006, 01:38

Usually its just the bristles within the motor getting stuck. Hitting it with a hammer is commonly the best method to free them up.

boganbusman · Post by **boganbusman** » 16 Nov 2006, 02:18

Yep, or with some cars you can even kick it from underneath

SomeKindOfMonster · Post by **SomeKindOfMonster** » 21 Nov 2006, 04:44

I used to use a jack handle, so when people asked if i was rough on my car, i could say, nah i don't use a hammer on the starter. But yeah, a good bash usually frees it up enough. Or buy a new starter, its not going to break your budget lol

xHaZxMaTx · Post by **xHaZxMaTx** » 23 Nov 2006, 12:10

I was always under the impression that the Porsche Boxster was for people who couldn't afford Porsche's. However, as of late, I've been hearing that Boxster's are among the best Porsche's there are. Anyone mind clearing this up for me?

Grez~Supra_RZ-S · Post by **Grez~Supra_RZ-S** » 23 Nov 2006, 12:36

I wouldnt say that. Boxters nowadays are for people who cant afford Caymans, which in turn are for people who cant afford 911s.

boganbusman · Post by **boganbusman** » 23 Nov 2006, 12:48

Yep, Porsches are built specifically so the cheaper ones aren't better than the more expensive ones.

I've heard that the Cayman could actually be faster than the 911, but Porsche wanted the 911 to remain as the flagship model.

xHaZxMaTx · Post by **xHaZxMaTx** » 23 Nov 2006, 13:03

I always thought the Cayman looked a little more agile than the 911, but that's just a guess, I've never really bothered looking at the specs.

Also, I guess the peeps that told me the Boxster was a high-end Porsche thought $40,000 was expensive.

RVD · Post by **RVD** » 23 Nov 2006, 16:47

I read somewhere that the fastest Porsche Cayenne (the SUV) is faster then the fastest Boxer. Dont know if it's true, but i believe it. The boxer just doesnt have enough power.

xHaZxMaTx · Post by **xHaZxMaTx** » 23 Nov 2006, 17:15

You mean Boxster? Subaru's have boxers.

steelsnake00 · Post by **steelsnake00** » 23 Nov 2006, 18:00

So do Porsches, ironically enough.