Project S2000: Part 32 – Fitting and Installing Turbo System Parts

Firstly, please excuse the phone pics. I brought my camera but forgot my memory card in my laptop. Oops. So anyway, it’s been a super slow burn on this project because life. But a lot of headway has been made since dropping the car off at Eimer Engineering. Chris at Eimer Engineering is familiar with S2000s and works on Dai Yoshihara’s race cars, so he was the right person for the job. This build also requires a lot of ‘trying things out to solve packaging problems as everything is custom and Chris is a willing partner to do these experiments. Here’s where we’ve gotten so far on making all the custom parts fit.

A goal of this project is to stay stealthy, so keeping the stock rear section of the exhaust was a goal. Won’t this hurt power you say? The combined flow area of the two pipes (assuming 50mm diameter each as I didn’t physically measure them) going to the stock mufflers is only about 15% less than the 3” mid-pipe, so it is a bit of a restriction, but a good compromise to stay stealth. For reference, the stock 60mm diameter mid-pipe is about 38% less flow area than my 3”/76.2mm turbo-back mid-pipe. The team at Eimer Engineering had to cut the stock exhaust where it splits from the mid-pipe to the twin exhausts and makes the transition from the 3” pipe to the stock rear section.

The stock exhaust actually has a nice Y-split which is better than many of the aftermarket offerings for the S2000. As we’ve seen many times, the Honda engineers really maxed out performance given their OEM constraints (budget, piece price targets, etc.) and it’s been hard for the aftermarket to improve on the stock Honda designs.

Here is the transition piece going from the 3” round to the oval profile of the stock exhaust before the split. As you can see, the area of the stock exhaust before the split basically matches a 3″ diameter pipe.

The exhaust from the turbo to the rear exhaust section is all 3” diameter stainless steel. It eliminates the resonator in the stock mid-pipe and also the little stubby side tube that acts as a Helmholtz resonator. We’re going to give it a try and see how loud the system is. We went to a larger diameter pipe and cat and eliminated the resonator which will increase the noise level relatively speaking. But we also put the turbo on there which acts as a muffler. It might be about the same loudness as stock. The major changes being we removed the stock mid-pipe resonator but added a turbo.

This is a GESI GEN2 Advanced G-Sport UHO (ultra-high-output?) cat and its EPA compliant for 2017+ vehicles. It’s 400-cell with a 3” diameter inlet/outlet and 4.5” diameter body. There is a model that’s only a 4.0” diameter body and rated for less power which makes sense. Smaller diameter = less flow area = higher restriction. You can see why I went with the 4.5” body. GESI makes a GEN1 model line for vehicles up to the 2016 model year that’s a 300-cell count. Interestingly enough, they are rated at the same power as the GEN2 with the 400-cell count. One would think the 300-cell would be lower flow restriction. Anyway, I decided to go with the 400-cell as it should be a little cleaner and still flow plenty for my 500 crank horsepower target. I had to get a new cat because my stock one is toast. Everyone who tracks an S2000 knows the stock cat breaks apart after enough track days.


  1. Do you still have that alternate vented hood? Seems like it would come in handy to dissipate the heat from the turbo considering how high that air intake is in the engine bay.

    Glad to finally see another post on this car. Always loved the chassis, it just needs some power to make it golden.

    1. I gave that hood to the owner of Project AP1 S2000. I’m staying completely stock hood sticking to the sleeper stealth theme. A NACA duct right in the middle of the hood where the intake is would be optimal, but that would attract unwanted attention. While sitting stationary, the intake will suck up some of the warm air coming off the manifold/turbo. But I figure in first gear, the car will be traction limited anyway. Once the car is moving, I’m plumbing cool air towards the intake, so it should be sucking in near ambient temp air. We could possibly fab up an airbox to completely isolate the intake from radiator air, but I don’t think it’d be worth the effort.

      1. That engine bay is looking mighty crowded, I don’t know if you could get some kind of snorkel to vent into the air filter like this:

        Yeah, I understand wanting a sleeper. I had my first car stolen within six months because I put some chromed aluminum 17” wheels on it. When I got it back (with some crap steel wheels) I used the insurance money to search for the lightest, yet stock looking aluminum wheels I could find. I eventually turned it into an auto-X car, but I was always mindful to remove the race wheels and slicks immediately before going home.

        Because of that initial experience, I have always tried to make my street cars look understated. I absolutely subscribe to the ‘sleeper ethos’….because, as you say ‘life.’

        1. I have to admit… I was eyeballing a Dodge Viper hood NACA duct… I talked myself out of it to stay under the radar. Some of the air from the driver side bumper duct will work its way into the engine bay. The passenger side bumper duct will be the primary way to plumb ambient air to the intake. When the front bumper is fully mounted, there may be a gap between the top of the heat exchanger and the top of the bumper opening. If so, we can make another air diverter plate to force air to go over the top of the radiator like the snorkels.

    1. I’m waiting to get my car tuned to determine the wastegate performance before I sell the one spare manifold. I’ve been driving it around, making sure all the small things are in proper working order before going in for a tune. I’m hoping to have it all ready by the end of September.

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