930 what mods? Turbo, headers, intercooler

[1979-930]

Originally Posted by Tonger

Derrick,

One of the considerations for the dyno shootout would be not only what the max HP but more importantly what the shape of the torque curve is. Long tube headers may help off boost torque and may help or hinder the boost threshold. I chose to go with TK and a divided system with twin scroll and dual wastegates in an attempt to get the boost threshold as low as possible. As it is, I've got a full 1.2 bar of boost under 3100 rpm using the GT35R which is a good fit for the progressive drivability that I was looking for.

I don't really care about what the peak hp number is except for internet forum bragging. What matters more to me is what the boost and torque curves look like in the rpm range where I spend most of my time (midrange). In this case, a low boost threshold using a ball bearing turbo was my priority. The accessibility of boost was a determining factor for me and the big peak hp number was just the icing on the cake.

Sounds like a similar build and ultimate goals with different headers. I'm only going to run 1.0bar or 1.1bar. Are you EFI? What wheel HP did you end up with?

Originally Posted by Tonger

One suggestion that I have for you is to look inside the secondary of the header you've shown and dress/grind off the areas that I've marked with the yellow arrows on the annotated photo. I would hate for either piece (especially the one at 8 o'clock) to come loose and go through your turbo after being heat cycled a few times.

I planned on it. I almost took care of it before taking the pic.
But thanks for looking out. You never know someone's mechanical level.


If the slip joints become an issue I'll just tig them closed and have the headers recoated. But they fit together really tight. I'll be checking for evidence of leakage just like Rawknee does.

[Tonger]

Originally Posted by 1979-930

Sounds like a similar build and ultimate goals with different headers. I'm only going to run 1.0bar or 1.1bar. Are you EFI? What wheel HP did you end up with?



I planned on it. I almost took care of it before taking the pic.
But thanks for looking out. You never know someone's mechanical level.


If the slip joints become an issue I'll just tig them closed and have the headers recoated. But they fit together really tight. I'll be checking for evidence of leakage just like Rawknee does.

I put it on a Mustang dyno while still tuning the CIS. At the time I was running 1 bar of boost and still had an AFR of less than 12 at redline. This run was done in a not fully optimized state. Still, the torque curve was very flat which translates into good drivability. This is the only dyno curve I have handy from that session - ignore the spurious AFR readings of 15 which happened after the run.

In retrospect, I wish I had simply gone EFI. At the time I didn't want to modify things 'too much' and kept the CIS. This meant a fuel head mod, adjustable wur, two new fuel pumps, 009 injectors, and larger diameter euro fuel lines and lots of time. At first I was lean, now I am too rich. This is part of the reason that I've increased the wastegate springs to 1.1 (not 1.2, sorry for the mistake) and installed a RPM switch. I need to get it back on the dyno again to see how it does with more air. There is a limit to how much I could dial down the warm control pressure and still have a decent AFR at cruise.

Finally, I am running a LSD and 8:41 ring and pinion. The short R&P makes 4th gear usable in the 930 gearbox again and really livens up the car - highly recommended.

[TurboKraft]

Tonger is the only guy I know whose CIS 930 has the problem of being *too rich* from peak torque to redline!

[RarlyL8]

The lighting in this picture is deceiving the view of the inside of the collector. There may be risen edges from the back-purge welding process but there is no slag that could cause a problem of any sort. We have never had any reported instance of slag issue in any of our header systems. Quality in our welding process is one of the things that separates us form the other manufacturers, we take that very seriously.

[Tonger]

Originally Posted by RarlyL8

The lighting in this picture is deceiving the view of the inside of the collector. There may be risen edges from the back-purge welding process but there is no slag that could cause a problem of any sort. We have never had any reported instance of slag issue in any of our header systems. Quality in our welding process is one of the things that separates us form the other manufacturers, we take that very seriously.

Rather than welding slag, this actually looks like extra material from when the collector was sanded flush or cast. If you look closely at the picture, there is a thin grey line over the periphery that looks like casting flash or sanding flash.

It's not a big deal, the section with the red arrow at 8 o'clock is just partially broken off. That's why I suggested that Derrick clean it up and take it the rest of the way off. Actually, I think that he must have seen it too when I pointed it out in his post.

Originally Posted by 1979-930

I planned on it. I almost took care of it before taking the pic.
But thanks for looking out. You never know someone's mechanical level.

[JFairman]

A carbide bur on a die grinder or roto tool would clean those raised edges off smooth in 30 seconds or less.
Or do it by hand with a rat tail file if you can get at them.

[gsxrken]

Originally Posted by Ken911

I spent some time on the phone with the guy from CMS who supplies header parts because i plan on making my own. He told me that they dont recomend slip flanges for turbo headers beacuse they tend to leak. He was willing to sell me set of double slip collectors but said he didnt recoment it for a turbo.

After I test fit Brian’s headers to my car I tack welded the collectors in place, removed them from the car, and tig welded while back-purging with argon as much of the slip joint as I could get at. For a car with heat boxes, I would HIGHLY recommend specifying the double walled joint, or welding them before you even turn the key. Very doable. I have no fumes in the car.

[kevinbodman930]

Welds look nice and tight.

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[1979-930]

Ditto! Those are nice. As a new to TIG welding welder that is hard to do. My welds are twice that width.

[pdqcarrera]

Originally Posted by Tonger ..."Equal length but longer and more tortuous vs. nonequal length but shorter with fewer curves"

My tuppence here... from Physics 101: Assuming both have the same I.D., the latter inherently offers lower pressure drop and less turbulence. Thus inherently the winner (though yes there are other important factors of optimum velocity to turbo inlet & gas pulsation delivery as previously noted by others). What is the net effect difference? Guess ~1% better acceleration, 1.5% higher peak? Dunno, only Tonger's dyno challenge will tell (unless of course someone has the software to model it), however I seriously doubt it's seat of the pants detectable either way.

[pdqcarrera]

Originally Posted by TurboKraft

Tonger is the only guy I know whose CIS 930 has the problem of being *too rich* from peak torque to redline!

Is this because of his injector selection? I'd have thought stock would suffice for his build...


BTW - major kudos and thanks to Tonger for posting the dyno sheet! Much appreciated.