3Bar Boost on a 4A - can it be done?

[nick.parker]

My plan is to twincharge my custom 4AGZE twinscrew configuration. Basically it would be a hardwired series setup. The SC is an Autorotor 2087. My setup will be ::

AirFilter -> Turbo -> Throttle ->SC -> Intercooler -> Engine


I initially plan on something like a KKR480 for a bugdet turbo with the oomph I think I want. Long term maybe something bigger and BB and Garret once / if it works well.

Basically I plan to run 1bar on the twinscrew (pressure ratio of 2:1) giving essentially a 3.0L-ish looking engine from not much above idle. Then with a turbo matched really nicely it would be slightly verging on undersized for the 'apparent' engine capacity so have the turbo spool up really quick, in addition to the immediate 1 bar of SC pressure.

1 bar from the turbo would result 3 bar at the manifold. At this point I imagine the power potential should be around the 500hp's. So my question is, can a 7-rib 4A block hold together? Or should I say plan on running 7-8psi from the turbo for a more realistic 2bar at the inlet manifold?

I am not really interested in big revs. The stock 7500rpm limit would be fine.

Cheers, Nick.

[oldcorollas]

no idea if block will break.. could.. but what fuel are you planning to run?

oh, and take vids

[Duk]

My plan is to twincharge my custom 4AGZE twinscrew configuration. Basically it would be a hardwired series setup. The SC is an Autorotor 2087. My setup will be ::

AirFilter -> Turbo -> Throttle ->SC -> Intercooler -> Engine


I initially plan on something like a KKR480 for a bugdet turbo with the oomph I think I want. Long term maybe something bigger and BB and Garret once / if it works well.

Basically I plan to run 1bar on the twinscrew (pressure ratio of 2:1) giving essentially a 3.0L-ish looking engine from not much above idle. Then with a turbo matched really nicely it would be slightly verging on undersized for the 'apparent' engine capacity so have the turbo spool up really quick, in addition to the immediate 1 bar of SC pressure.

1 bar from the turbo would result 3 bar at the manifold. At this point I imagine the power potential should be around the 500hp's. So my question is, can a 7-rib 4A block hold together? Or should I say plan on running 7-8psi from the turbo for a more realistic 2bar at the inlet manifold?

I am not really interested in big revs. The stock 7500rpm limit would be fine.

Cheers, Nick.

How do you come up with 3 bar manifold pressure with you expected supercharger and turbo boost pressures
Do you have any more photo's or a link you can share with us to show your supercharger set up?
I wanted to buy 1 of RonRob's kits, but he ahs gone very quiet

[Forcefed6]

I can't forsee that Liberty w/a intercooler doing an overly good job at cooling that intake charge produced by 30psi+ (or 45psi).

Good luck with it... Interested to see the outcome.

[oldcorollas]

1 bar turbo boost (2 bar abs) multiplied by the SC's 2:1 volume ratio = 4 bar absolute pressure and 3 bar boost?

edited cos i'm stoopid

[roadsailing]

just run the turbo wastegate off the plenum pressure and keep winding it up until you get the power you want, see how it goes.

OC, dont confuse him

[nick.parker]

How do you come up with 3 bar manifold pressure with you expected supercharger and turbo boost pressures

Well its ball parkish theory numbers. It ignores lots of the simple physics involved. Talking in terms of boost is actually confusing from a calculation point of view, esp. with series compressors.Its better to think of absolute pressure ratios. Even the the SC is really a volume ration device, just figure out its pressure ratio for the boost I want when there is no turbo there.

Consider an SC cramming air in to an engine such that the engine consumes as much air as an engine twice its capacity (at some operating point). Lets pretend that we have 1 Bar BOOST (2Bar ABS manifold pressure). Lets call this a pressure ratio of 2, as 1 Bar ABS goes in, 2Bar ABS is at the manifold. Now, if you double the inlet air pressure at the supercharger inlet to 2 BAR ABS say with a turbo. So again a pressure ratio of 2 : 1. So 2:1 x 2:1 = 4:1 overall ABS pressure ratio. So Boost will be (4-1) = 3 Bar GAUGE.

Think about it like this ::
The turbo is effectively supplying 1bar of boost to a 'supercharger & engine setup' that appears already twice as big as it was naturally aspirated.

Nick

[nick.parker]

I can't forsee that Liberty w/a intercooler doing an overly good job at cooling that intake charge produced by 30psi+ (or 45psi).

The Liberty W2A is fantastic with the SC14 probably adding 20kW worth of heat to the intake at at full boost . I have done a fair bit of thermocouple logging to verify its effectiveness. Generally the outlet air is within 4degs C of the coolers average water temp.

But Yeah, probably will add a second cooler after turbo, maybe a small air to air with ducting from under the car (AW11) as I currently use for the W2A water cooler. Also have played with water injection to, so would consider this.

The heat will be extreme!

Nick.

[Duk]

Interesting maths that makes sence. I'm going a twincharger route too, so any factual information is gold at the moment .
Temperature wise, wouldn't you expect to see relatively sane discharge temps from the SC? Given the efficientcy of the twin screw and a well spec'd Garrett BB turbo that shouldn't be working that hard for it's living.
Wouldn't compound supercharging be more temperature efficient than trying to achieve the same pressure ratio with just 1 compressor (either or)?
After all, multistage air compressors aren't just built like that for the fun of it. The same pressure could be achieved with just 1 stage. If you could find room to fit an intercooler between the turbo and SC, the efficientcy should go up even higher
Just thinking out loud here....

[roadsailing]

pressure goes up, temperature goes up. compressor inneficiency comes in to it, but any time you compress a gas and keep the volume constant, it will get hotter!

[Duk]

pressure goes up, temperature goes up. compressor inneficiency comes in to it, but any time you compress a gas and keep the volume constant, it will get hotter!

Yes I know. But what effect does changing the pressure ratio of a compressor have on it's efficientcy? Shouldn't it rise, resulting in lower discharge temps.?

[nick.parker]

I LOVE talking about twincharging, but I was really hoping somebody might be able to comment on how much a 4A block can handle.

I have a video of an unknown 4AGTE dyno, with the vehicle (Corolla and front wheel drive) making 483 WHP at 9K rpm I think! But that is HIGH revs and just over 2Bar. I want this at 7000rpm so I would be making more torque and hence having higher cylinder pressures.

I want to know things like, do you need to put cylinder liners in for any hope in hell of not breaking a block at this power level? I want to know if what I am wondering about is too stupid to bother considering. I am sure 2 bar boost would be great fun too....

Regards, Nick.

[roadsailing]

oh, not necessarily, as the air going into it will be "thicker"

depends what you mean by efficiency too.

the pressure ratio of the compressor wont change in the case of twincharging anyway, higher pressure in, higher pressure out.

EDIT:

as for what pressure can one handle, i;d look at the turbo 4AGE escort dude's results, he is running boost pretty high, i think you will run into issues with charge cooling and detonation before you have to worry about excess boost splitting the engine.

[oldcorollas]

what was the result of the "sleeving a 4A block" thread?

[Duk]

Yeh sorry nick.parker, kinda hijacked your thread there.

Do you mean 30psi 4agte, shinybluesteel? I was thinking the same