S15 SR20DET Turbo Swap -- Spriso Motorsports

[MBrannon]

The the tranny tunnel need to be hacked for s14 5 speeds?

[spriso]

The the tranny tunnel need to be hacked for s14 5 speeds?

The transmission tunnel requires ZERO modifications for a standard 5-speed transmission. The X-member only needs a minor modification for the transmission mount, not the total rebuild like I illustrated for the 6-speed.

Michael

[spriso]

Wiring

Since James' car already had been rewired using an EZ-mini 20 wiring harness, the only part that needed to be redone was the EFI wiring harness that connects to the engine. The S15 wiring harness is a little different than the earlier stuff, but with the correct wiring schematics it is not too difficult to figure out. Like most EFI wiring harnesses, it is way too long however, so it needed to be modified to suit our application perfectly.

Here is what we started with:



One of the things that Nissan does with each wiring harness is they put the part number on it. This is something that I like to retain for future reference. Here is the original part number ID tag:



I carefully removed this tag and put it into James’ copy of the factory service manual incase anyone needs to reference it in the future.

The importer did not provide us the other end of the white plug which connects to the chassis harness, so I cut this off and built new terminal connectors using OEM Hitachi connectors from our friends at http://www.vintageconnections.com

Before:



After:



As you can see, the amount of wiring going to the chassis is much smaller than the original plug. We can eliminate many of the wires such as power steering, and air conditioning wiring. In the end you end up with a much simpler wiring harness that does exactly what you need and nothing more:



Compare that to the first shot and you can see how much stuff was pulled out of the harness that is not needed.



On each harness I build, I add a new part number tag with the original part number and our company name and date (that way they will know who to blame!)



Inside the car, a removable relay box was built that houses the relays for the EFI system, fuel pump, seat heaters, headlights, fog lights, horn, etc. That is mounted on the kick panel on the driver's side of the car:



The EZ Wiring harness fuse box pokes through the panel here and has a cover which covers the fuse box (not pictured):



When we are done with these conversions, I make wiring schematics which show the layout of the relay box, and wiring pinout for the ECU similar to this one. Again, this will help someone down the road figure out the modifications that were done to the harness...



Enjoy,

Michael Spreadbury
Spriso Motorsports

[Alvin]

Brilliant, Michael.

[spriso]

It runs! Last night Eric and plugged in the ECU, checked to see if we had fuel and spark and turned the key! Another SR powered roadster lives!

Photos and a video link this weekend!

Michael

[spriso]

A very brief update!

At speed:



At rest:



More soon,

Michael

[Alvin]

OMFG!!!!
Look a the lip on the rear wheels.

Offset: it's what separates the men from the boys

[dbrick]

That's great stuff. What color is it?

[shifty]

I saw this car in person a few weeks ago - stunning! Could be the nicest roadster I've ever seen.

IIRC it's Plymouth Prowler Orange.

[spriso]

More Details You Will Never See!

One of the problems when running the 6-speed transmission from the S15 Silvia is the lack of a electronic speedometer output. Nissan does not put any provision for a speed sensor on the transmission as the signals for the speedometer come from a sensor located on the differential that sends an electronic signal to the ECU via the ABS computer.

Since we don't use the Silvia rear end, nor the ABS computer, we need to fabricate a method to make the electronic Classic Instruments speedometer work. The simplest method is to use a Hall Effect sensor on a sprocket to create a signal that the speedometer can read, and this is exactly what we did!



The theory behind this is pretty simple. A sprocket with a tooth passes by the end of the Hall Effect sensor which has an embedded magnet in the end. Each time the tooth passes the sensor, an electronic signal is generated. Since the Classic Instruments speedometer has a wide range of possible signals that it can read, this is a great solution to the problem.

First a sprocket was designed in AutoCad that would fit on the drive shaft, and would have teeth that fit the manufacturers specifications. This was then sent out to be laser cut and a few days later, we had a sprocket that looked like this (click to enlarge):





A simple bracket was built to hold the speed sensor so it centered on the teeth on the sprocket and mounted to the flange on the differential assembly:



And here is a shot of me holding the sprocket simulating it in position:



It was finally installed on the Ford 8" differential (which I will write about in my next post) and wired up:



There you go, a detail that few will ever see or care about, but what we take great pride in building!

Michael Spreadbury
spriso motorsports

[spriso]

Rear Differential

So, we have 250+ horsepower, a 225/45/16 tire mounted on a 7.5" wide wheel, and a driver with a very heavy right foot. The stock H190 might last with this much power and rubber, but the lack of a good, easy to service limited slip differential, and a limited range of service parts made the H190 look pretty obsolete.

The car's owner, James, also wanted rear disk brakes, and I wanted service parts if he as ever able to blow up this rear end... there was only one solution that made sense: A Ford 8" rear end.

Kevin Desirello had positive things to say about the Ford 8" that he put under his customer's SR20DET powered car, and he was very helpful answering my questions about their application. He recommended talking with Currie Enterprises http://www.currieenterprises.com and I found them to be very helpful.

After spending quite a bit of time with them on the phone, and measuring and measuring what we wanted to do, an order was placed and about 3-weeks later a huge box arrived at the shop with this inside (click to enlarge):









Custom lower shock mounts were built and roadster comp rear springs installed:



You can see the massive 225/40/16 tire is as close to the spring as we dare to go!



And installed in the car:





Because we narrowed the rear end 1/2" each side (to fit the wheels and tires) the frame was cupped to clear the calipers:



The stainless 2.5" mandrel bent exhaust system was finished from the muffler via a v-band clamp (check out Eric's beautiful weld on this one!)



And up and over the massive axle assembly:





The rear end hooks up great, can be repaired at any hot rod shop in the country, and was a bolt in with built in LSD and rear disk brakes... Yes, it is heavier than the Mazda RX-7 setup, but this should be 100% bullet-proof, and sometimes there is a lot to say about that...

Enjoy,

Michael Spreadbury
spriso motorsports

[Alvin]

insanity!
i opted for the hall sensor before I knew the it wasn't needed for the S14s..good to see it can be put to use on the roadster!

we placed the rx-7 calipers lower to clear the frame rails...was that an option?
I'm sure the 225 clears fine static, but do you have any inner fender claerance issues with the top of the tire/sidewall on hard turns?

you are the roy brizio of Datsuns.

[xeddex]

....like whoa!

[GoldHawg]

Once again, my wife hates you and I love you! Awesome!

If one wanted to just leverage your careful work and order one from Currie as well, can you tell us exactly what to ask for?

Thx!!

[spriso]

Alvin wrote:

we placed the rx-7 calipers lower to clear the frame rails...was that an option?

That is exactly what we do on our Mazda rear end swaps as well. I asked Currie if we could clock the calipers differently, but their bracket only works in this position otherwise you run into hand brake cable routing issues.

I'm sure the 225 clears fine static, but do you have any inner fender claerance issues with the top of the tire/sidewall on hard turns?

It is close, but so far, no rubbing with some pretty vigorous testing...

GoldHawg wrote:

Once again, my wife hates you and I love you! Awesome!

This seems to be a reoccurring theme! We hear that comment quite a bit around here!

If one wanted to just leverage your careful work and order one from Currie as well, can you tell us exactly what to ask for?

No problem, I actually leveraged from what Kevin had sent them previously (but with our modifications of course!)

I have seen several Currie axles under roadsters, so this was not the first time that they had done one. In fact, there was one very recently listed on eBay for fraction of what a new one costs-- I would get in touch with that seller if you are a serious buyer for one of these!

We actually shortened the axle housing 1/2" on each side from the standard roadster angle width. Pinion angle is 6-degrees, and Currie has the pinion offset listed in their customer files... Send me a PM and I can send you a scan of the spec sheet for what I ordered.

Let me know if you have any other questions!

Michael