T/bodies on a factory car?

B

Bagel

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Fellow Frogger
Joined
May 1, 2003
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Ok, so we know by now that throttle bodies are the ultimate answer to normally aspirated intakes, right? So why aren't they factory equipment on any car (that I know of)? They provide tractability, fuel economy and the best power/torque gains throughout the rev range. They're basically (VERY basically) an intake on each cylinder right? They couldn't be much more expensive if made/ordered in production type numbers.

What's the deal, power pug nuts?
 
Emissions, economy.

In essence, getting the things you name is easy. You dump tons of fuel and air into each cylinder.

As a basic equation, you can't get more energy out of your motor than exists (in chemical form) in the fuel. That's not to say that you can't make an engine run more efficiently, but when we're talking brute energy increase, extra energy out = extra energy in.

Besides, I thought quad throttlies were of limited use outside of high revving, narrow powerband, applications You're essentially making your inlets very short, which reduces restriction and helps breathing but also removes the low-rev range torque you get from the resonant effects of longer inlet runners.

Hmm... The follow is from a (complicated!) engine textbook I picked up at work:

"high volumetric efficiency can be obtained at certain speeds by the use of long inlet pipes"

(high volumetric efficiency = engine running with less vacuum, more air/fuel, in the cylinders.)

"at higher piston speeds, the flow restriction offered by small D/B ratios (ed: long, thin pipes) becomes dominant and volumetric efficiency falls"

"as pipes become shorter, the maximum gains in volumetric efficiency over that with no inlet pipe grow smaller, but the range of piston speeds over which some gain is made grows wider."

Finally, for multiple branch manifolds which feed multiple cylinders:

"at high piston speeds manifolds may cause appreciable sacrifices in density at the inlet ports."

So, I guess, if you want a car you can rev the crap out of and drive like a race car, get the quad throttles. If you're normal (ie not us) and just want a car with tractability, economy and which doesn't need to rev cleanly to 7000rpm, get a regular inlet manifold.

:)

<small>[ 30 June 2003, 10:23 AM: Message edited by: Gus ]</small>
 
Well, car makers measure cost per component, 1 throtle can do 1 car, 4 can throtles can do 4, so why spend the cost of 4 in 1 car when the margain, is at most minimal... and as above. cheers Xq
 
XQ, spot on mate,

ECONOMY rules the car makers world for production cars.
Other things that the plenum chamber configuartion gives is another magic word, FLEXIBILITY in tuning and drivability of the car in all road conditions.
 
From what I'd heard, t/b's give you the power at higher revs, while allowing you to keep tractability at low revs - with a suitably mapped ignition and ecu of course. Surely you could tune them for economy/performance, as most cars seem to be tuned. Take the Saab for example. They whack a low pressure turbo on for increased efficiency and performance. This is an extra part, lots more development money (ignoring the fact that they were one of the first turbo-using factory car manufacturer) - does this exclude t/b's for factory equipment, or is what Gus says true, and they kill normal driveability? Some of you guys/gals have driven cars set up this way right? First hand feedback?
 
There are cars that have them factory.

The Toyota 4AGE 20V engine has them. It is NA.

Then there are the Nissan engines. The RB26DETT has 6 and the SR20DET found in the GTiR has 4.

And soon my 205 will have them. head_ban

Darren
 
generally speaking TB's will give you power at , and only at the RPM you want. The design of the pipes is dependant on the airflow of the head/valves, duration of the cams, ambient temperature, length of the pipes, diameter of the pipes, shape of the pipes.

As a rough guide shorter pipes give max power at high end and least torque (least restrictions at high RMS), long pipes give low/mid range power/torque and good economy.

(it is as I understand them)

<small>[ 30 June 2003, 01:49 PM: Message edited by: tekkie ]</small>
 
Darren, the 4AGE is the Lexus engine isn't it? that's pretty old-hat right? Are TBs just a way to try to make it last?

And can I ask why you started with a 1.6 for your project car?

Thanks,

Chris.
 
The Lexus engine is the 1UZFE which is a 4L quad cam V8. The other Lexus (Soarer) engine is a twin turbo 2.5L six being the 1JZGTE.

The 20V 4AGE is found in Japanese cars of the late 80's/early 90's I believe. It was not used in any Australian released vehicles.

I started with a 1.6 205 because it has the better gearing for track work and was available at a good price when I was looking. It won't be 1.6 when it goes back on the road though. It will use the 1.6 block but will have 1.9 crank and rods to get the 1.9 capacity back.

With respect to throttle bodies on my car they are pretty much mandatory. For the power I am chasing and nitrous being used as well I needed all the fuel I can stuff into the engine as I can. The standard inlet just wouldn't flow enough air and afford the tuning that we require. AND we will get more power out the engine because of this.

Darren
 
4age was used in Corrola and MR2 range of cars.
Lexus IS200 used 3G series motors.

they were the motors used in the AE82 corollas and AE86 Sprinters in Japan.

They have since been used in MR2 and come in NA, Turbo and Supercharged guises. The latemodel MR2 also got the 20Valve head which is (lets face it) awesome.
<img src="http://www.4age.net/gallery/engines/003n.jpg" alt=" - " />
4AGE Turbo model shown. The early 4AGE model, I think, didnt have the multi TB's just a single TB into the plenum chamber (with the exception of the TRD engines - shown).
<img src="http://www.4age.net/gallery/engines/015.jpg" alt=" - " />

4AGE 20v 1995 - 1999 NA
125kW @ 7400rpm
165Nm @ 5200rpm

4AGZE 20V 1991 - 1995 super/turbo charged?
126 @ 6400rpm
206 @ 4400rpm

****************
These figures are from the <a href="http://www.4age.net" target="_blank">www.4age.net</a> website.
Not verified by yours truly
****************
 
I have quad tb's on both my cars [205 and gtir -factory quads] and dont lose anything in tractability etc. I think it comes down to cost as they are still putting drum brakes on late model cars, surely you would think that discs are just as cheap as drums en masse but apparently not.

jr
 
That top 4AGE looks pretty trick - that couldn't be standard could it? Carbon fibre plenum chamber, stainless mandrel manifold etc...?

Darren, are there advantages to the 1.6 block? Or is this talked about in your other thread? Sorry, I'm too fat and lazy to look :p
 
...and dont forget the bmw M...the latest incarnation carries 6 (six) throtle bodies...ie.one per cylinder....tied up to a quad exhaust its no wonder why they sound so magical throughout the rev range...

cheers
dino
 
there is no doubt about the TB's being great for sport cars, Their tunability especially at low end of the RPM is the problem.

But if you want power.... and that magical sound of induction.... lol
 
All of the BMW 'M' engines since the M1 have had one throttle body per cylinder.

Generally, the use of throttle bodies shouldn't cause loss of tractability through non-use of longer inlet runners if you have a similar setup on the upstream end of the throttles, and make sure that the throttles themselves aren't too large a diameter for the engine capacity. One way longer runners affect torque is that the inertia of the mass of air within the runner rams the air downstream into the port, a very mild supercharger effect. So a reasonably long intake pipe on the outside of each body should have the same effect, AFAIK.

In some systems there's also the effect of resonant pulses (from the valves closing) reflected back along the air column and returning, having a similar effect, but this is more to do with a tuned length rather than simply a long runner.

Stuey
 
There was a supercharged MR2 with the 4AGZE engine. They were in Corolla Seca twin cams as well as MR2. They fit in a Morris Minor without too much trouble, but you gotta fix the brakes!
 
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