I don't think kraftwerks makes a kit for the fit anymore.

 

Cost isn't too much of the issue, it's the support. No one supports the SCs anymore, if KraftWerks was still behind their product 100%, I would have just purchased that.

But I'm also wanting to learn Turbos, as it's a more economic option (I know I said cost wasn't the issue), but if I make a mistake and I have the right precautions like gauges, alarms and etc, making a modification myself will be possible.

The issue is I need power at the 2k RPM range, and I want to coast at 60mph with load, or 70mph with load, or 90mph with about 600lb load... Sadly, I'm 200lbs, gf is 120, kids are 30 and 35lb, and the road trip equipment is another 300lbs or so (two spare tires, clothing, stuff I purchase while on road trip).

So, back to the question, is there a smaller turbo to give the power at the 2kRPM range? or will the SR20det have what i need without having to downshift to get back up to the speeds I want (downshifting == poor gas mileage).

 

Should just do a K swap. Factory reliability and more power/torque than you'll get with a tiny turbo. Less BS for a daily driver.

Any reason you don't want to do that? Just exploring all avenues.

 

I have only seen K20 swaps here on these forums, I don't have the tools or the experience to do THAT much conversion to my car, and at that point COST would be an issue as I would have to get equipment and mistakes WILL happen.

I did consider it, I also considered getting a backup L15 for 1,100$ from an online shop, or for a few hundred less at the local junkyard.

My girlfriend's PT cruiser has a turbo, and it's integrated, which is kind of cool, and very small. I'm trying to keep the MPG at the best possible, which is one of the cool things of my gf's car compared to mine. Hers going 85mph beats my honda fit at 85mph just on gas usage alone, and she has a much larger engine than I do (2.4L), which is a shame, only because I'm forced to drive in 4th gear to maintain the speed.

 

So is maintaining higher cruising speed your goal or fuel economy? Turbo will not get you both. If your in boost all the time you will be using more fuel, but will be able to maintain speed more easily. The PT Cruiser Turbo has a fairly big motor (more torque) with a turbo and long cruising gears. Even if you slap a turbo on the Fit your going to be on boost all the time due to gearing at higher speeds.

Look how poorly the small motor + turbo worked out for the major car manufacturers in the real world... It didn't. Real world mileage of the Cruze Turbo is sitting around 26?

Sadly, if you want the fuel economy and the speed you need a bigger motor, higher displacement. K swap is well documented for the GD and there are pre made mounts.

Honestly you'd probably be better off in an Accord, the Fit sucks for hauling with passengers (as evidenced by your roof rack, which is also killing your gas mileage and power due to aerodynamics). The Fits versatile for sure but cargo room with passengers certainly leaves something to be desired.

I will still follow the turbo discussion though because I'm interested. Carry on lol

 

The maintaining high speed would be a give and take, I will be saving gas, if I'm not in 4th gear revving at 6K rpm, as opposed to boosted at 2.5K rpm at 80mph. I would gain a lot more MPG if I can maintain those high speeds consistently.

The 98 accord I had had great trunk room, but hard to access as opposed to roof rack. The civics I've used are too cramped. The inside of the fit is open, has a fridge in the trunk area which the kids in the back seat can use to get some nice ice cold water or milk. We also store the bare essentials inside the car, the rest goes on top. The loss with aero dynamics will get fixed soon, getting Thule/Yakima roof boxes, they are nice and aero dynamic, and let me store more efficiently. And the rear hatch will have a spare tire attached to it a-la CRV.

And my understanding, the PSI from the turbo can be regulated at a flight line of 5~8PSI (like the KW SC) so controlling how much boost goes in at all times wouldn't be that much worse than the SC.


So, my interest is in a balanced turbo application. Although, for a project, this setup would be great (wish I could get a second Fit, my GF wants my car, it's more fun)

 

Cte8624, the 2nd turbo is a black top s14 unit. It needs an impeller and rebuilt. It was abused.

 

You're exaggerating the RPM differences (or downshifting past 4th gear without realizing it). There's nowhere near a 2.4x spread between the gear ratios.

Regardless, I don't think you'll get any fuel milage improvements with a turbo. You will be able to avoid downshifting some, but the milage won't improve. To really improve the milage, you need to reduce the air resistance—by going at a slower speed and/or cleaning up the aerodynamics. (A hard-sided roof carrier, while better than loose cargo aerodynamically, is still a pretty big drag. The Fit even without anything on the roof isn't all that great aerodynamically.) Driving scrupulously at the speed limit will do more to help your milage than any engine modification I can think of, except maybe swapping in a diesel, which isn't a fair comparison at all.

If I were in your shoes, I think I would seriously consider getting a different vehicle altogether rather than putting a lot of money into a turbo setup for the Fit. A '12-'13 Chevy Impala, or a '11 or newer Grand Caravan/Town and Country, for example, could be had at pretty reasonable prices and should provide more comfortable and convenient longish road trips for a handful of people. An Impala might actually beat a Fit with a roof carrier for gas milage at 80+ MPH (though I'm not about to bet one way or the other); the minivan probably wouldn't, though I suspect it may not be too far behind. Neither is as much fun to drive spiritedly, of course, but how much of that is there on a cross-country trek via Interstate? Anyhow, that's what I might do—but I'm not you.

 

I disagree with the recommendation of the T25. Its a great turbo size and nissan and mitsubishi versions have both PROVEN time and time again to be reliable and great small power adders

However, for something only as far as highway cruising power, I think they are a bit big. I think cruising, with our engine rpms, that they will actually hurt gas mileage quite abit, say going up a long steady hill.


I think a K03 or slightly better K04 is more the type. They were used by VW/Audi for the soul purpose of gasmileage. So small they boosted very early on their 1.8 and 2.0 liter motors. Ran WAY out of breathe past 5000 rpms on those motors.

On our motors, I think the small bore and light rotating mass would put their sweet spot (K03 especially) right in our cruising range.

DSM, what do you have to say? Im curious if you thought about a K03 for this application.

I think most of the turbo enthusiasts have forgotten about the "tiny turbo" market that the K03 and K04s dominate (in terms of affordability and minor power gains)

If T25 is the winner for the build, I think a sleeve bearing mitsu unit is better to use, the ball bearing nissan version will be in boost constantly with our motor past 4k rpm no matter what, and will make a severe impact to gas mileage, due to how much more air the T25s move when compared to the K03

A bonus with the K03 units, the inlet and outlets on the cold side are a LOT easier to adapt to the fit, given the size! Hell, you could get lucky with an old diesel truck's radiator hose cut up to fit. Some of them are 2inch inside diameter, perfect to skip spending money on intercooler piping and couplers.

The other bonus with a K03, no intercooler will need to be used with the dual cooled units, though with older K03 turbos with no water cooling, a small side intercooler could easily fit under the hood and simply have a small 6 or 7 inch aftermarket radiator fan cooling it. Some of those fans are only $15-20 on ebay, they are usually made for oil coolers

EDIT for the record, with my mods (plugs,intake,muffler-delete) I do not have to use full throttle to pass people or go up hills. Only time is very large uphills when passing 2-3 people

 

I have only recommended one Fit build use the Borg K03 and it was reluctant at that.

Guy was insistent about "spool" and other concerns.. but as soon as the novelty of having a turbo its self wore off he was left wanting more. He wound up with a "small" EFR unit (6255) and much happier last we spoke.

There are a variety of small turbos to choose from, but the K03/K04 if even gotten for free I don't suggest. Usually Garrett, IHI or MHI offerings are most economical. Particularly the smaller MHI turbos.. 9B, 12T, and 13G.

I really would not go any smaller on a Fit than a T25 flanged GT2554 or a TD04 13G. They are more efficient on pump gas, they spool very quickly and they leave some room to grow later on.

Another thing to consider.. the smaller the turbine wheel, the more wastegating these low-boost stock-block Fits need. Not everybody is comfortable pulling a turbine housing off and taking a dremel to it. Like pretty much anything up to and including your average Nissan/DSM T25 or GT2554 will need.

But if the OP thinks a turbo is going to save him money on gas.. he is somewhat misguided. If you are driving at 80mph you are well beyond where the Fit cruises efficiently anyway. It can save you a downshift, certainly.. but anytime you are in boost you are ingesting more air and fuel than the engine otherwise could have done without the turbo. That's where the added power comes from after all.

This spool time we are throwing around is somewhat abused - To have any sort of apples/apples comparison of spool times we need to reference the gear and transmission we are talking about. Also, where you first start to make positive manifold pressure and where target boost is achieved are two different things.

My HX52 on the DSM might start to make 1-2psi @ 3200rpm in 3rd gear, but I dont have 20+ psi till ~4500 and the run we spike to 38psi was just shy of 6000rpm. So that's something else to consider.. what your target boost is will determine spool time as well.

 

If I was to make a turbo setup on my L15 GD, I'd use the unit from the VW 1.8T. Smaller than a T-25 and spools even earlier on a smaller engine. High availability and better sizing for our small, low revving 1.5

 

I've followed this thread from the beginning and I'm unsure as to how you got the idea that sitting in boost all the time would equate to improved gas mileage? Or why 6k in 4th is required to go 85 mph tbh.

 

I went 6k in fourth once... or twice, I believe that was or was close to terminal velocity LOL

Top of third is ~80? I'm usually not looking at the speedo at those times so not sure.

 

That is the Borg K03. You do not want to use that on our 1.5. On paper and in practice it is a poor match. Don't get hung up on theoretical spool. There is much that affects spool, including what you understand "spool time" to be.

Right? That is the first time I have run into that train of thought. Turbos have been on passenger vehicles since the 60s, increasingly common and they are still as poorly understood as ever.

 

WOW... you must've been over 100mph, no?
Yeah, just about. I usually rev out 3rd on the hwy with moderate traffic, and stay in 4th till it clears up, but I don't think I've every done 6k rpms in 4th.... in 3rd all the time, though.




Great discussion in here guys... Glad DSM is back... congrats Chris on the build & magazine coverage.

 

115 indicated IIRC but I don't quite remember if I upshifted to 5th and then looked down at the speedo or looked down at the speedo and then upshifted. I am thinking the latter because I probably checked the tach and speedo at the same time and then upshift. Anyways yes it was over 100. (closed course disclaimer).

 

Yes, you're right, I downshifted to third, oops... but my point I believe still stands.


[quote] To really improve the milage, you need to reduce the air resistance—by going at a slower speed and/or cleaning up the aerodynamics. (A hard-sided roof carrier, while better than loose cargo aerodynamically, is still a pretty big drag. The Fit even without anything on the roof isn't all that great aerodynamically.)[/quoted]

Noted, but again, some extra force always helps go a long way.

I have a Jeep 2001 V8 4.7L (for camping, and shorter field trips)
PT Cruiser for my GF's DD.
Fit 08' for myself

the I-System is for getting from state to state... I do plenty of spirited driving through the hills of California:


Or offroad fun in Nevada... which I do plenty of:




The person you hesitated on suggesting the Korg, what was his end objective? was it purely a faster spool? was he trying to maintain certain speeds? what positive PSI did he have at 2,300RPM? was that a concern of his? Why was he unhappy with his setup? Not enough positive pressure in his intake at certain speeds? was he hitting a cap? The person that got this built out, does he have a link on the build or numbers available on the net someplace?


My only thought process was that reducing my downshifting would save gas, as a 4th gear at 5krpm using more gas than 5th gear at 3k. Even with some boost. (I'm not looking at something as large as a +10psi in the intake).



So, I'm not looking at high power. I'm looking at low positive PSI in the intake, I'm not looking for high revving my motor out, but the option could be there.

I'm not speeding when I'm going 80mph, the speed limits on highways in parts of TX are 85mph, and I struggle with nothing but 200lb load to maintain 80mph (hint, I weigh 200lbs).

Speeding Through Texas: 85 MPH Highway Opens - ABC News



I'm sorry I haven't responded in a week, I have classes, and had little personal time.

I'll wait for the reasons why DSM's guy was unhappy with his K03 turbo setup.


I'm not looking for the best 1/4, or 1/8. I'm not interested in being remotely the fastest car on the highway.

 

Thanks! She recently made just shy of 600whp, still on low-ish boost (mid 20s) but now I am having intermittent ECU issues so hibernation came a bit early than expected.

I'm getting the feeling you will probably remain steadfast in this idea regardless of what I have told you.. though maybe you just want further clarification and you will take my explanation to heart..

Assumptions about immediate fuel consumption 4th gear at 5k rpm and 5th gear at 3k are useless without considering load, which will be directly tied to manifold pressure. As in engine load.. usually done in grams/rev/cylinder or similar metric. In other words, pas

Just going 80mph which I understand is the speed limit, having driven through north and west texas a few times on my way out to NM/AZ/CA, is going to kill fuel economy. A turbo is not going to help you, especially one that spools quickly and here's why:

5th gear at 3k with 5" vacuum, 5th gear 3k with ambient pressure, and 5th gear at 3k with 5psi above ambient are not going to have a linear relationship in fuel consumption.

One of the big things you are neglecting is that not only does it take more energy (fuel) to make the added torque that comes from boost at low rpm.. you will be running a richer Air:Fuel ratio than you would at ambient or pulling vacuum and simultaneously lower spark advance.

You will be using proportionally more fuel. So instead of say, a line on a graph with a 1/1 slope starting at the origin, imagine one that as soon as it gets to a certain point starts to curve towards vertical (infinity/no slope). Similar to this:


Not only that but at 80mph the engine is turning over closer to 4000rpm. A turbo that builds boost just by looking at the gas pedal is going to make this worse. Aero/Cross section and displacement are not on your side here.

Adding to that - the turbo takes energy to run in the first place. There is no "free lunch." The only things you can do are drive more passively, reduce speed or reduce friction/drag.

 

I am craving the information, not just being told what to do. I like being informed before jumping on any bandwagon.


Ok. Now going towards the turbo, where can I get the parts reliably? Can I gut it from an existing car at the junk yard? If so, what specific models? And then I can look at tools and equipment to get the parts. Then I need to get someone to make the header, I assume I rip the header out of the car I gut (if it's from a car) so that a new header can be made from the existing mounts.

Also, reducing the outlet on the air intake portion of the turbo, will that have a negative effect? (thinking slimmer piping to the intercooler), if I have a blow off valve at a lower PSI, would that give me the power without requiring the high fuel usage? Again, looking at just a little extra power, not something too large.


ARGH, this will be fun now.

 

I trust DSMs judgement. I personally like tiny tim turbos, spool and response are very important to me, more so then actual power. I want the car to jump, not stampede!!

I will say this, my buddy shamaus in wisconsin hooked me up with a good T25 and a T25 that needs a rebuild, so whenever hondata comes out, the T25 is getting its chance of glory on my car lol