CRX HF EcoTurbo?
 

Well gentlemen.

Is it worth it to turbocharge a 1990 Honda CRX HF for increased economy?

I read an article in SuperStreet a loonngg time ago, in which a turbo Honda S2000's fuel economy jumped to 38 mpg. All because it took him less time and throttle to achieve highway speed.

I was thinking maybe a Mitsu 13G with an adapter plate to the HF manifold, plumbed straight into the throttlebody with no intercooler. Boost pressure would be low, only 5 psi or so. I would like to retain the factory 240cc injectors.

My biggest concern is tuning with OBD-0.

Do you know if it will deliver the power in the low end? That's the key, from what I have read. For the best FE results you will want more power on the lower end of the RPM band and you will want as little delay as possible. This unit offers that?

Doesn't the CRX HF have pretty high compression ratio already and with a turbo you want to have lower compression on your engine so the increased pressure doesn't cause pre-detonation.

The TD04-13G is fairly small. I can't say for certain due to variables, but full spool at 5 psi would probably be around 2700 rpm. I spend most of my driving in the 1800 to 3500 range. The extra power would be nice for getting onto the highway.

The GT15 would probably be a little more efficient for my needs, and spool a little faster... However, that would increase the price by quite a bit.

9.1:1, so not terribly high. There's a lot of guys running 15 psi+ with much bigger turbochargers with that compression.

The short answer is no.

I know Daox is right about the financial cost of the turbo charger. It wouldn't pay for itself for a prohibitively long time, if ever. I just looked up the prices on these units. Not any cheaper than others I have causally researched. $2K - $3K is a lot to pay for a little more FE. Your earlier response raises questions too. You say you normally drive in the 1800-3500 RPM range. An HF has taller final drive gearing than the VX and so you might be driving at some high speeds to make 3500 rpms on the freeway. Not all that great for FE. Still, I don't think anyone would dispute that there would be some gains, with modest driving technique changes, and that you would also have access to the power you seem to want. If costs are not part of how you value the mod, go to it. And please post a build thread with testing of results. I know I'd like to read it.

A guy on d-series.org boosted his civic for the sole purpose of better FE. He tuned it so that his engine would be in neutral vacuum as much as possible to increase pumping efficiency . He also re-calibrated the fuel maps in his ecu to run in lean burn mode. I forget how many MPG's he was getting but is was up there. I'll try looking him up and post a link if I find it.

I found this on that site: I did some FE testing 64.8mpg - D-series.org. Is that the one? If so, he seems to have a turbo for power but relies on lean burn for higher FE on freeway trips. His average FE, tank to tank, would be interesting to know.

I would be surprised if just adding a turbo helped FE in any way.

Using a turbo to bring a car back to "acceptable" performance when something else has been done (e.g., lean-burn, downsizing the motor, etc.) is a well-trodden path to FE. Just ask anyone with a Cruise Eco.

It might be fun to run a 1st-gen Insight 3-cylinder with a turbo in a CRX. :D

-soD

Gasoline engines don't see much of a FE boost when turbo charged.
If you be good and drive them easy you can milk a few more MPGs out of your vehicle but the mod wont pay for its self.
It would be nice to have more power and MPGs, in that way it could be worth it.
I wouldn't try going non-intercooled.

I'm looking at:
$20 for the TD04-13G from a friend
~$40 in steel and bolts to fab up the adapter and exhaust flange (I weld)
~$100 in exhaust tubing between the downpipe and compressor-to-throttle-body pipe
~$80 in plumbing and adapters for the oil, plus welding a nipple to the pan
~Free chipsocket (Nothing my Weller WES51 can't handle)
~Free tuning (BRE)
~Keeping 240cc injectors, since the boost pressure is low

In short, there aren't a lot of expenses.

No fancy tuning needed.
No blowoff due to the low boost pressure.
No intercooler needed due to the high efficiency, and I don't care if I lose 15 hp due to heat soak
No whinebro fuel pump needed .


In short, for under $500, my car would actually be able to merge onto the highway.

Highway, I need to remember to pay attention to my RPM. I just know my fuel economy starts to drop off at about 68 mph. I think that's about 2500 rpm or so.

I have gotten 55 mpg with this car before. That won't be possible again until next summer though. Back to the snow tires.

Welcome to Michigan.

That reminds me, I need to do a block heater.

That is an amazingly cheap set up. If you do this, contribute some real data to these discussions with some good testing, please? Could you get yourself a rigorously recorded baseline of mileage for a while before you install the turbo and then with the turbo installed? Drive it under similar conditions for a few weeks, before and after? I'd like to see what you get.

That sounds about right, man. With your taller gearing, assuming that CRX engine is otherwise similar. On my car, with your gearing, I might expect the line to be at 2500 rpms.

I'd buy the turbo but do the block heater first. The block heater is certain to improve FE: http://www.metrompg.com/posts/warm-up-idling.htm.

I say do it. Not only could you get better FE, especially highway, but the car would be more fun to drive. BTW are you sure you have 240cc injectors and not 190cc's???

It shall be done. My results will be a little skewed though, I average about -5 mpg with snow tires.

All 88-91 Civic/CRX to my knowledge are 240cc.