TB's and turbo

[feral4mr2]

bit of a dunce one here i cant answer for myself.
does a turbo need to have a throttle body after it? for example a automatic car, no gear changes. can the turbo run free into the i/c to inlet manifold.?

thanks.

[roadsailing]

you need a TB somewhere, old turbo cars had it prior to turbo, but i think this was a hangover from the suck through carby days.

you would need some sort of throttle, even in an auto car to get off the line in drag racing, might as well be a functional one.

but for running at WOT, nah it doesnt need a TB

[feral4mr2]

engine is 4agze retaining s/c and stock TB location. thinking this morning instead of running turbo into TB - s/c like i have started to, run turbo directly to i/c bypassing the TB and s/c altogether.
i am thinking being auto and turbo wont spool up til late, boost regulated by a external wastegate that this would work..?

thanks.

[Crazyracer]

How are you going to control the engine speed if you don't have a TB.

Leave the TB on the manifold.

As ShinyBlueSteel say you can have the TB before the super and turbo chargers, but its got to be somewhere. Better after the chargers.

IC should be after the chargers to cool the air thats been heated by compression.

[feral4mr2]

did you bother to read my post? the stock TB is mounted in the stock location before the s/c.



thanks for your non imformative post.

[roadsailing]

yeah it will work having the TB before the turbo, but better on all accounts to have it after, then you could just run a 4AGE inlet manifold which from what i have heard are a lot better than the ZE one anyway.

[feral4mr2]

this is on a twincharge set-up, the stock gze inlet manifold will be kept where it is. (gze inlet manifold is capable of 300hp + ). i already have a tried and proven 4agte set-up utilising the ge inlet manifold.

what i am pondering is the air filter and AFM feeding both turbo and s/c (stock s/c set-up AFM - TB - s/c - i/c - inlet manifold). but the turbo instead of going to the TB and through the s/c etc. is to bypass it alltogether and run the turbo directly to the i/c (both s/c and turbo feed into the one i/c) then off to the inlet manifold. so no TB to operate on the turbo side of things. would just need a valve doobie of sorts to stop the s/c blowing back down the turbo line before it spools up.

sound feasable?

[fixeruperer]

its this "valve" thats hard to get the way im doing it is differant to yours but i need this "valve" to find one big enuff thats not massive on the out side is quite hard.

[feral4mr2]

i need this "valve" to find one big enuff thats not massive on the out side is quite hard.

i've researched nearly every thread on various forums regarding twincharging, bypass valves etc. it seems a large external wastegate is the best option.


i've started doing the set-up like normal.... air filter - AFM - turbo - TB - s/c - i/c - inlet manifold. wasnt going to use any bypass valves etc. s/c operated via the ECU as normal, no valves or switches or anything.
am making custom 2.5" s/c oulet pipe, will use a 2.5" inlet/outlet i/c (w2a), custom 2.5" pipe into modified inlet manifold.

just throwing a idea into the air (well forum in this case) as to bypassing the s/c alltogther with the turbo and straight to i/c.
was in the shed a moment ago looking at stuff, running the conventional way is the simplest way to do it pipe plumbing for sure. i spose it's been proven to work (cameron datto?).

[thechuckster]

F1 cars ran TB's ahead of the turbos - but we're talkingvery old skool way of doing it.

I think cameron datto's race weapon still pushes the air thru a TB.

Simplest solution appears to be StockMcStock's twin-charged RB30 on performanceforums:
air-filter ->turbo ->SC .>FMIC -> TB -> plenum.
with a simple bypass valve (made from a large external Wastegate) the feeds air post-SC back to post-turbo

http://www.performanceforums.com/for...highlight=twin

[JustenGT8]

Interesting concept...so what you are proposing is no throttle control on the turbo plumbing at all? Given they are driven by exhaust gas and you are still controlling that, the turbo won't just spin it's nuts off.

Where i do see a problem is in transient response...you have no throttle control of the turbo airflow. The compressor wheel response to changes in exhaust gas flow (ie being driven by the turbine wheel) will be much much much slower than you need to get any sort of throttle response ie you NEED the throttle to accurately meter air into the engine. On gear changes etc the engine will over rev badly as the inertia in the turbo provide more air than the engine needs.

Short answer is NOT feasible...Crazyracer was on the money.

[oldcorollas]

to put it simply, without throttle, there is no throttle response

the engine is totally seperate in terms of function to it's induction... all it knows is if there is air or not. more air = faster, less = slower..

to not have a TB with the throttle means there is no way of controlling the engine speed or output. ie, once the turbo spools, the engine is WOT, and it won't slow down until you remove spark or fuel.

diesel doesn't need TB as the engine speed is controlled by fuel... so the turbo can just blow freely...

you could seperate the induction from engine by using a second TB... and using the pre SC TB to regulate the boost generated by the SC... but that all gets complicated as the SC is positive displacement, and turbo is not.... etc....

[roadsailing]

all good points mad above

and a bit OT, but i still think the best way to twincharge is just turbo blowing into supercharger with one or two intercoolers and no switching valves at all.

but thats just me, id try it that way before anything fancy.

good luck with it!

[feral4mr2]

thanks for all your replies, i'll just continue on doing what i am in the conventional set-up.