The Mega Supercharger 4AGZE thread, using twinscrew charger

[trdee]

I'm simply responding to your previous requirements which stated 190kw as your intended power goal. Now you're changing your requirements on me

If you want your 4A to feel like a 3L engine, you will need around 10-12psi of boost from my experience playing with GZE adubs in various states of tune for the last 7 years. This will not net you anywhere near 190kw, More like 120-130RKW, if your intercooling is up to scratch and you run optimised intake and exhaust systems. It will feel strong, much stronger than the headline power figure would suggest. I still am not sure about going without an IC though. The setups you mention are factory cars running like 7psi etc. you will still be around a 1.8 PR, which is ~120degC on the above chart.

Dunno man, you won't know till you give it a go! But my experience suggests intercooling is very very important to get good results at this level of boost through a supercharger

[nick.parker]

If you want your 4A to feel like a 3L engine, you will need around 10-12psi of boost from my experience playing with GZE adubs in various states of tune for the last 7 years.

Yep, and if you want your adub to feel like a V8, run 18psi with the stock cams . I did and I used to describe the low end torque to people as being like a v8 - it wasn't really too much of an exaggeration - well at least below 4000 rpm!

And I can only imagine how much better the twin screw will be versus the SC14....!

[jondee86]

Ahhh.... the 269hp was just an arbitary figure that popped out when I compared the two chargers at 100kPa boost. My original post mentioned 10-15psi, and certainly to begin with, I wouldn't be looking for more than 10psi. I am a total noob with chargers and have no real interest in maximum power. From what you guys are saying, and from what I have read, I expect the result from a twinscrew to be more performance and less heat than a SC12. Every comparative test between Roots type and twinscrew type chargers comes down quite heavily in favour of the twinscrew.

I hear what you are saying about intercooling being a good idea, and if this project gets off the ground, I will monitor charger outlet temperatures closely. And I will definitely use a cold air intake.

I take it that both of you guys were running the stock GZE intake manifold and 8.9:1 compression ? Any thoughts on running with the stock smallport 10.3:1 pistons ? Or should I be investing in some GZE pistons or 9.5:1 forgies ?

Cheers... jondee86

[trdee]

I was running an AW11 4A-GZE, which has 8:1 pistons in it. Stock manifold on my engine yes, but have played around with various other setups including a better efficiency air to air cooler and multiple water to air setups.

Twinscrew definitely beats roots, and even in terms of roots chargers, the SC12 is a piece of shit. So whatever choice you make it should be a vast improvement

Smallport pistons can work, but you will need to pay extra care to making sure the tune is good. Start to get any decent det events and you will smash the ringlands to fucktown pretty quickly. 10-15psi probably won't be possible on those pistons without intercooling or water injection. Unless you run E85.

[jondee86]

So I've looked at what it will take to get a Sprintex S5-210 strapped onto my engine, and decided to start out in a modest way. Low boost and try and keep the costs under control until I have a system up and running. So I have bought a GZE smallport intake manifold, and will start to mockup the brackets and ducting on my spare longblock. Going to use the 10.3:1 pistons and stay under 6psi. If I decide I want more, I'll upgrade to GZE pistons.

While the GZE manifold cops a bit of flak, it will flow all I need just now, and it is way easier to use the factory manifold than having to design and build a custom manifold. Hopefully, I can score the lower GZE mounting bracket as well, and that will give me all I need for designing a mounting plate for the charger. The ducting will have to be custom built, probably 4mm aluminum sheet and 10mm thick flanges, with enough joiners to avoid precision alignment requirements

Cheers... jondee86

[trdee]

Good luck, keen to see how it goes

[knightrous]

If your going to buy a new Sprintex unit, maybe check out the Harrop HVT900 as well. It's based on the Eaton TVS units and they are pretty feckin awesome for a roots-ish blower and is even able to run up to 2.2PR with good effeciency.

[jondee86]

Having read a lot of stuff about centrifugal vs turbo vs Roots vs Twinscrew in the last few weeks, there are a few things that seems to shine through... turbo is the shit for high pressure ratios, centrifugal will get you there with a bit less heat and some waiting time, unless you use the wastegate control idea. Twinscrew beats out all the older style Roots blowers on efficiency and temperature rise. Yes, I see a lot of blah about the HTV/TVS and what is said might be true... but as I outlined a few posts back, what happens when you hold high outputs for a long period concerns me not a lot

This is the S5-210 dybo chart...



To get this project into action I have to settle on a charger, and filtering through the sediment that clogs the interweb, I can see that Sprintex is used as the basis of some big name aftermarket kits. These companies had the option of choosing other charger types/brands, but settled on Sprintex, and that is good enough for me.

I have located a SC12 lower mounting bracket, so will be able to take a few measurements next week, and get drawings underway.

Cheers... jondee86

[jondee86]

Before I forget... there is still one big question I have not been able to get a handle on yet. What kind of performance curve do you get when you gear the charger down to limit the max pressure ? For example, if I used a S5-150 instead of a S5-210, the smaller unit tops out nicely at just under its maximum rated speed for 1.4bar, but the larger unit has to be run at about 70% of maximum speed.

Am I correct in thinking that since both chargers will be discharging 148l/sec @ 8500rpm engine speed, that the pressure rise in the manifold from idle will be essentially the same ? That is, performance from idle to redline measured by butt dyno will be the same ?

Cheers... jondee86

[trdee]

more or less. the bigger charger may have a bit more parasitic loss but then again you are spinning it slower so maybe not? put up the plots for both so we can have a look.

[jondee86]

Here ya go... Sprintex S5-150 dyno chart...



Doesn't look as if there is much between them...

Cheers... jondee86

[trdee]

Yeah it would seem there is not a great deal of difference. Considering that you have more headroom with the bigger charger I would go for that one.

[jondee86]

For sure !! They map these things for 15psi, and although I am quite happy to start my learning curve with 6psi on the high comp pistons, further down the track I would look at rebuilding one of my engines with GZE pistons and shoot for 15psi. I already have a set of GZE injectors that will do for starters, and I believe there are some 440cc/min Supra injectors that would be OK for up to 15psi. There seems to be a good case for upping the throttlebody size even for 6psi, and I will be looking into that to see what is readily available from a Toyota... Supra I guess ?

Water to air intercooler would definitely be on the cards for 15psi. The IC is physically smaller, and getting hoses to the front of the car is far easier than running tubing. Plus, I don't like cutting holes in my car.

Cheers... jondee86

[trdee]

Harreh found a noticeable jump by swapping out the GZE throttle body for an N/A 4AGE throttle body and boring out the J-pipe at the same time. Very cheap and simple upgrade.

The 4A-GZE 365cc injectors will do you till around 150rwkw, so you probably won't need to change. However if you do get to the point where you need more fuel, 440cc injectors from a 7M-GTE or a gen 1 3S-GTE will slot straight in, and will flow enough for up to 200rwkw

[knightrous]

For sure !! They map these things for 15psi, and although I am quite happy to start my learning curve with 6psi on the high comp pistons, further down the track I would look at rebuilding one of my engines with GZE pistons and shoot for 15psi.

Kenne Bell have an article about running varying PR's on their twinscrews chargers and have specific models (H = 2.0PR, S = 1.4PR) to ensure you get the best performance for that level of boost.

http://kennebell.net/KBWebsite/SC_pg...s/H_Series.htm



If I have it right, according to the article, running the bigger charger with the higher 1.8PR will have higher parasitic losses and higher charge temps then the smaller one at 6psi (1.4PR).

EDIT: Extra thinking...

If your running under the internal PR of the supercharger, your parasitic losses & charge temps will be higher as your compressing the air to the internal PR inside the charger, then the air is expanding again to become a lower PR outside the charger. On the other side of it, when you push the blower pass it's internal PR, it starts acting like a roots blower as the extra pressure is generated by restriction between the closed valve and the outlet port on the supercharger.

If that is all correct, you would want to run the supercharger at it's internal PR to get the best out of it.