Not finding much love for small turbos in the Honda world so thought I would ask.

GTX2860R is rated for ~450hp at the crank. Big 2.4 should spool instantly? Probably fall a bit flat on the top end?

Had a few rental cars now with 1.5 liter DI turbos. Love that low end grunt those make. Something similar possible with port injection on the K24?

Maybe run boost control to ramp in some more power at the top end to keep the torque curve flat?

 

Using a larger a/r like a .86 would help with the top end power and probably very little effect to spool time. Still pretty small turbo for a 2.4L but if the extremely quick spool is what you’re after that what it would do. Keep in mind a proper sized wastegate and routing would be critical to avoid boost creep as much as possible

Traction will also be more of an issue than you think

 

Oh dang I have the .64 housing here collecting dust. Maybe too small? Would be simple with that internal gate and single exhaust port on the Z7. Looks like a .84 internal gate is an option just not in the ni resist.

I almost want it to boost creep (on my terms) up at the top. Dial down the boost at the bottom and let it run what it is going to run at the top. A flat 300ft/lbs sounds okay to me. At 7,200 that is 411hp. Should be inside the capabilities of that little hair dryer?

2" charge pipe to keep the lag to a minimum? Outlet on the compressor is only 2" OD. I haven't started looking too much at charge pipe size vs HP capability.

 

Would it be in the 2012-2015 Civic SI? What type of driving would it be for- drag racing, road racing, street enthusiast, etc.? With lots of torque down low RPM you might just roast the tires, although it’ll probably have a limited slip differential I assume…That’s why most people choose a large turbo on Honda FWD cars.
I can see it working out though and being lots of power when needed at the touch of the throttle.

 

It came from a 12 Civic Si, so yes it is LSD. It is in a CR-Z, I have build thread here on H-T. Now it needs more. It is a daily driver that needs a healthy amount of passing power for mountain highway driving. Plus the lulz.

So boost by gear, a boost map, adjustable DBW throttle, LSD, and traction control should make that sort of power rather friendly. 245 sticky bunz also help....

Civic Type R at 2 liters does ~320 lbft early on but falls off really quickly on a smaller turbo than the 2860. Bigger displacement should be able to spool as fast but the bigger turbo should carry the torque longer?

Maybe part of the secret sauce of these tiny turbo OEM engines is the electronic wastegate? Turbosmart is starting to make them available. Wonder how compatible their driver is with Hondata's PWM boost solenoid control.

Direct injection is for sure a big part so how much is that worth? Is the tiny turbo big torque down low even possible with port injection without going to race fuel to prevent knock.

 

You should be good for mountain driving. Not for drag racing though, but if that’s not what you’re going for then I think it’s all good.
I think it’s possible without race fuel because it’s a 2.4 liter rather than the 2.0 in the CTR, so you should be able to make at least 300 wheel torque down low without fuel being an issue on 93 octane.

 

I don't think the Turbosmart egate will work with Hondata - it requires a 20A output on the ECU.

For street, small turbos on Hondas are where it's at. Torque early means a fat power curve. Agree that you should probably use a bigger turbine housing in the 0.8+ range to allow you to move more exhaust.

 

Yeah I was just looking at the manual for the egate last night. Would need a standalone or some driver between gate and ECM. I thought they came with a driver.

Tial has that fancy stainless v-band housing in .86. How well do v-bands endure the heat and weight of a turbo on daily driver? I know the modern diesel pickups are fully v-band but their turbos run much cooler and are fully supported on pedestals so the v-band doesn't do any weight bearing.

Maybe the bolted inlet flange is better?

 

4 port solenoid is probably fine after doing some more research. Not sure the E-gate gains me much without going to a standalone that could hold the gate open at cruise for slightly better VE at light load.

 

I think the V bands endure the heat and weight of the turbo fine in daily drivers.

 

I am having trouble finding any examples of daily driven v band turbine housings. I personally have v bands on all of my exhausts with zero issue but nothing hanging the turbo from a v band.

 

Anyone watch Richard Holdener videos? Specifically about turbos moving the torque curve upward but not actually changing the shape of the curve? Just acting as a multiplier.


Taking that logic and applying it to my small turbo idea I should end up with a torque curve of roughly like this? Take the Z7 curve and multiply by 2.2. Taking some liberties with spool and how far the torque will carry.

Does something like that seem like a reasonable expectation?

 

Get an Arashi/Kinugawa 20G td05h divided turbo thats evo based. Preferably evo 10 for the 12cm turbine housing.. Youll have the best spool possible and hit close to 500hp to the crank.
The cheapest divided setup. And for diesel like setup id bet my $ on a twin scroll setup. My 84x89 hits 1 bar at at 3500, and im 400cc smaller from you.

 

Twin scroll would probably be a great idea but the Z7 is one of those exhaust manifold integrated into the head designs so it only has a single exhaust port.

Probably helps my quick spool goals at the expense of maximum power.

Let me see if I can find a compressor map for that evo turbo and compare notes.

 

That td05 20g has a compressor map that goes to 600 CFM, maybe a bit large for my goals.

 

600 cfm is like 500 hp. Non divided you can get a g25-550 .49 a/r. The turbine flow rate is ~15lbs/min and thats for about 430 hp. It will come alive VERY fast but its expensive.

 

Help educate me on calculating turbine flow requirements. Where does that number come from or how is it calculated?

 

Turd buckets! Hondata FlashPro, that I already have, doesn't support boost control on the PCM for the K24Z7.

 

600cfm is approximately 57lbs/min which is about what a good GTX3071R can do, whichis about 530whp MAXIMUM. More than enough, but that 600cfm is at over 2.4PR which is over 2bar of boost pressure. It's gotta SPIN to win.. ;-)

 

But what about the turbine side? How does 40lbs/min input equal 15lbs/min out?

 

Well I put in a feature request with Hondata. Probably a long shot. Looking to see if they will add some CAN bus capability in the form of a CAN connected IO board. This would allow the 9th Gen SI to keep the ECT2 and ELD functional while adding support for boost solenoid control, flex fuel sensor, wideband input, and Hondata traction control input.

Also just requested CAN message access in general. Let the community sort out the IO board.

Again probably wishful thinking but it doesn't hurt to ask.

 

Turbine wheel is a gas expander. Its not flow ratio altho we call it like this. More gas can pass but it wont expand inside the wheel.

 

Found the maths on the Garrett website.
https://www.garrettmotion.com/wp-con...3_Expert-1.pdf

Ran the numbers for what I have and know. Plotted them using the previously posted desired dyno graph. Seems the compressor is up to the task. Maybe got a little greedy on the spool time but it should work.


Now it would kind of be a matter of can I get the exhaust gasses out?

Played around with the BorgWarner match bot application and got roughly the same numbers. They have a turbine flow calculator that was showing a pressure ratio across the turbine of 5 or so with their .64 turbine, much less on the .84 turbine. The delta across the engine wasn't terrible. I think they were showing 23psi intake and 35psi exhaust on the smaller housing.

 

I don’t understand the math calculations but I’ve seen that sized turbo over the years and for your goals I think you are all good.