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Project #OGiantKillerCRX: Turbo Homework and The 250-whp Goal

  • Posted: 01-04-2016 10:36 AM
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Mulling over this project a little more, I am wondering, as I approach the 30th anniversary of this car's publication in Road & Track as the original giant-killer CRX, how farfetched would be to try and achieve that feat today? Matching a Corvette's 14.4 sec quarter-mile and a .94 g on the skidpad was accomplishment enough in 1986, but today the little CRX would need to muster a 12.0 sec quarter-mile and 1.01 g on the skidpad to match R&T's numbers on a new Stingray! Well-tuned Hondas are capable of these numbers, but…with a ZC engine? With 6" wide wheels? And would it still be a streetable package?

A little Google search led me to some theoretical calculators, and to achieve a 12.0-flat quarter-mile run the car would need to make at least 250 hp to the wheels. That is a lot from a 1.6L with an outdated turbo. If we assume roughly 10-hp per pound of boost, I will need to pressurize to about 12-13 psi. Will my turbo be able to produce that kind of boost efficiently?

After realizing the heart of my build would not only be under the hood, but actually dictated by the turbocharger itself, I decided to look a little deeper into the part I had and began to wonder what actually came out of the car.

There are not many identifying marks on the turbo. The compressor outlet has a distinct etching on it, the numbers "10039804.". And then there is a casting mark showing the number "80." On the turbine inlet, there are a few casting marks reading "0.45," "17B," and "IK4". Lastly, I can see a "19" on the center section.

Based on the bolt pattern in the turbine inlet, I determine this is a T3 turbo but, other than the .45 A/R, I don't know what these other markings are for.

Out of curiosity, I decided to delve into my library to do a little research. The oldest Jackson Racing book I have is from 1991, and while the kit is mentioned in there, there are no specs on the turbo itself.

I did find it odd that they listed the DOHC CRX application while this was never a North American car. In subsequent catalogs, this application is not listed. Perhaps Oscar gave up on trying to import and federalize CRXs as a business and there was no need to list the kit any more.

Given that the kit in the car, while not an HKS kit, was supposedly developed for HKS by Jackson Racing, I dusted off my oldest HKS book. A 1988 Master Catalog from Japan.

Unfortunately, I cannot read Japanese...But reading this chart tells me that a T25 turbo was specified for my turbocharger package.

But… my turbo has a T3 flange. A quick Google search and a ruler confirmed it.

Farther back in the book, there are more turbocharger specs. And based on this, it is very obvious that I don't have an HKS turbo kit. Not a book-spec one anyway.

I suppose that should not be so surprising. If I have my facts correct, part of the reason this car is even in the 'States is that Jackson got it here to develop the kit for HKS. It isn't hard to believe that the kit might have been prototyped with a different set of parts than what ended up in the production kit. Heck, even in the R&T article, the turbo is called out as a "Hitachi twin-blade" turbo. Getting an answer here would be awesome but I suppose I'll just need to deal with what I've got!

Meanwhile, I found and purchased a brand new HKS turbocharger manifold from Japan, and I sure am hoping it has the same specs as the one I have here!

It was quoted as an EG Civic ZC manifold on the selling site. Unfortunately, I don't have any newer HKS JDM Master Catalogs so I can't see any specs on what this part should be. I don't want to assume that it is the same manifold I already have, especially since it kinda looks like the turbine flange has a smaller hole on it. Could this be a T25 manifold?

If it is, then I guess I'll be needing a new turbo. The good news is that opens me up to a world of new and modern Garrett turbos. Both good and bad news are that I would no longer be able to run this AC compatible turbine outlet any more.

Good because that thing is horrible looking for power and that it would not be wise to marry myself to a completely unattainable part in the case it should break. Having a new outlet fabbed up would seem to be the ticket for power. But bad news because I getting farther and farther from keeping the package original, and keeping the AC is going to become a challenge.

But hey, the standard turbo has 130,000 miles on it and is 30 years old. It might not even be up to the task. And I'm not even sure what the specs are.

For these answers, and to perform the rebuild, I'll need to contact a qualified rebuilder. Heeltoe's very own David Walker has given me his recommendation: Blouch Performance Turbo

Apparently these dudes are responsible for some of the best turbo rebuilding work around, and have been in the industry forever. I have a pretty high degree of trust here. I'll be calling them soon for more info. I'm hoping they'll be able to clue me in on if my 250-whp goal is realistic or not!

Right now, it is all riding on the new manifold I bought, so I am going to need to get that sucker here as fast as possible to see where I am at with the turbo situation.


HondaPro Jason
08-23-2016 10:30 PM at 10:30 PM
This is a piece of Honda history. It's so awesome to watch you bring it back and learn more as you push towards your goal. I look forward to seeing it in person someday soon.
Administrator Note:
And we'll look forward to showing it to you!

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