Turbo BS Thread

[Moderator note] I recovered his thread using TW's photobucket magic...here is his post:

Twin charged 2007 Mazdaspeed 3

By Tim Clark

Basic overview:

I started this work in Spring 2013. At that time car had most of the basic bolt on stuff- plus a FMIC and a GTX3071R and was tuned to around 370HP. It still has the stock ex.man, cat back exhaust, and engine internals.

My new set up has a TRD supercharger positioned in series to blow into the big turbo. The supercharger runs constantly (no clutch) but can be bypassed at any level of boost. Currently it is set to open the bypass valve at 15psi. At that point the valve (a 3” electronic throttle body) opens and the turbocharger sucks air without any restriction of the supercharger.




My purpose was quite conservative- I didn’t want more HP- but I did want to see if I could get rid of or reduce the dreaded lag of the big turbo (compared to the K04).
Like others I missed the spool time of the KO4. My goal was to do all the work myself and spend $1000. max. In the end I went to around $1100.
The project is now basically completed and I’m really satisfied with the result. The initial feel is much more like driving the K04 again- but with the big turbo power higher up. The power is linear- and the change over feels seamless (since the s/charger is not deactivated at any time). I’m running (as before the project) 24psi with 50/50 methanol- and going easy on the pedal low down!.
I’m not a “pro”, and need help from others with tuning- but I do know that this project has worked.
For those of the community who are interested I’m writing a more detailed description of the four parts of the build:

1. Positioning of the supercharger.

The systems main component is a supercharger from the 2005-2009 TC Scion. This is made by TRD (Toyota Racing Development) and is identical to the Vortech V5. It is driven by a 2’ long drive shaft. Basically I went for this because it was cheap ($400. Ebay) and a quick measure up showed to my total surprise that it would fit!!
On the Scion this s/charger had some well known problems- mostly related to bearing failure on the pulley end. The positioning on the Scion puts the shaft directly above the exhaust manifold- and it is exposed to serious and constant heat. I realized quickly that this would not be an issue on the Speed 3- since the shaft would go above the intake manifold instead and the exhaust manifold would be at the rear.
The shaft may be separated from the Supercharger body and I located and installed it separately (see my 3rd step).
First I installed the body of the supercharger on temporary brackets (a modified shelf bracket from Home Depot!)- and placed my Cobb MAF and cone filter on the outside of the supercharger intake. Without the drive shaft the s/charger was “dormant”- but to my surprise did not pose too big a restriction on the turbocharger until higher up the rev range. It was drivable- and hence I proceeded to be able to keep my car on the road and move the project forward in stages. My wife was intrigued that putting a supercharger on the Speed 3 had actually made it (temporarily) slower- and we had some laughs over this!.



2. Power steering conversion.
It was already apparent that the drive shaft would clear the Speed 3 intake manifold- and that its length was perfect. However, the stock power steering pump/hoses were an obstruction. After hours of measuring/bouncing ideas I decided to get rid of the stock P/steering. This really was a last resort at the time- since I was aware of the various issues and problems of electric hydraulic pumps- particularly (ironically) those made by Mazda! In the end I opted for a tried and tested pump- the one off the 1991-95 Toyota MR2. This has a rugged build and has a high reputation in the “Stang” community for those are who are getting rid of belt driven power steering. In the photo’s the pump is visible on the passenger side of the engine compartment- at the front of the vehicle- it has a rubber cover that obscures it a little.



I adapted the stock Speed 3 high pressure hose to couple with a 2000 Mazda Protegé hose which had the correct end fitting. It now appears that the Protégé hose can be used on its own without modding the Speed 3 one. I did not use the controller/sensor set up of the MR2- so the pump runs all the time and requires heavy duty wiring with a 75amp solenoid of off the Speed 3 ignition.

In hindsight having now completed this work and looked carefully I see that it may still be possible to retain the stock Speed 3 steering pump- and reposition it deeper under the supercharger pulley on modified brackets. It looks very tight however. I may have a go later on as really wanted to keep the original pump.
With the steering converted to 12 volt hydraulic I again paused work and drove the vehicle for a couple of months. The steering felt good- but with a constant noise (normal) from the hydraulic pump- which could however be easily drowned by the stereo.

3. Drive shaft position

With the stock p/steering gone- there is a nice space for the drive shaft- plus there are a number of strong fixing points exposed. I fabricated two separate heavy duty brackets at this stage- one for the s/charger unit, and one for the drive shaft pulley housing. All the metal came off the shelf from Home Depot. This was the most time consuming and tedious part of the whole thing. It took this amateur fabricator about five days in the garage to get the brackets tacked up, welded and drilled.
All of the fixing points for the brackets are existing bolt holes on the Speed 3. It took some thoughtfulness, but I was able to place the supercharger without cutting/modding its Scion brackets in any way. I did this in case of failure and the need to resell the supercharger.




While some stock components can be retained in this conversion- the stock (or aftermarket) top mounted intercooler cannot. There is insufficient room- and probably insufficient cooling. The stock air conditioning hoses remain in place- but are adjusted- with the main rubber hose going over the top of the s/charger drive shaft.
I used the stock Scion supercharger pulley which is rated at 7psi. They are available at up to 14 psi (seemed risky to go higher). The pulley has one groove more than the Speed 3 belt system- but it fits well and is adjusted by placing shims behind it for exact positioning.
I was delighted to find that Dayco- has an online measurement tool for their belts- as opposed to just going by vehicle type .Hence the new belt came straight off the shelf at Autozone for $28. The new belt is about 8” longer than stock one.
Since the supercharger was now turning- I needed to provide its lubrication. I just put a “T” adaptor on the Speed 3 oil pressure sensor-(above the oil filter housing) for a source of oil. Currently I’m draining the oil from the supercharger with a hose running directly into the stock dipstick pipe holder as a return- since I’m not keen on drilling the Speed 3 oil sump -which is the process on the TC Scion.


4. Air intake and bypass system.

The entire stock/aftermarket intake system on the Speed 3 (filter/short ram/TIP etc) needs to be removed- and the only reusable parts will be an individual MAF housing and a cone filter if you have them. Basically the new intake is a “one off”. I made mine in 3” aluminum pipe (I love siliconeintakes.com for all intake modding- not the cheapest- but everything in one place).
The bypass valve was a little tricky- and I experimented with a couple of designs including 12v water/gas valves which are cheap and air tight but the bore was too small. The only type that would give a full 3” flow were throttle bodies.
I opted for an electronic throttle body off a 2012 F150/Mustang- readily available on ebay for under $50. It’s also possible to use manual throttle bodies with an actuator moved by boost pressure- but this involves more work.
The cool thing with an electronic TB is that it can be activated by a boost/RPM/Window switch etc. I modded mine so that it closed all the way and also converted the 12 volt supply to 5 volts ($10 DC reducer off ebay) as I discovered that the 12v was proving very hard on the internal plastic gear ring in the throttle body- since it opens and closes “hard” when not computer controlled- as it is designed to be when in normal service.



I used a 3” aluminum blow off valve T pipe on the intake side of the Supercharger as a return port for the re-circulated air (I’m not keen on venting to atmosphere) - and then I cut the side of this T pipe and mated it with a Spectre MAF adaptor plate (Pepboys) - thus making a flange for the F150 throttle body. A local shop did the welding on the intake pipe and flange adaptor for $50.
I opted for the simple approach on this design, trying to keep as much stock as I could however in the end the need for space meant that the battery had to go to the spare wheel well in the back of the vehicle and I modded a set of heavy duty jump leads for the new power supply.





I used a Spectre flexible 3”hose to connect from the T pipe/bypass flange on the supercharger to my Cobb MAF and filter. I was reluctant to use the flexible hose- but space was really lacking by the end of the project- and this has done good service so far.
The Cobb has been with me for my four years of modifying this car. It probably is undersize for this application- but it has always held a tune so well and I like its solid design. Why get rid of something that works so well?.
Also, as prior to this conversion I’m still running 50/50 Methanol on two number 3 nozzles mounted just before the Speed 3 throttle body.


Conclusion. January 2014

So………...VERY pleased with the results so far. It feels very different to the GTX3071 on its own- with way more pull lower down the rpm range. Plus I’m surprised how linear and smooth the acceleration is. Currently it is still on the same tune (by my friend Alan Jackson of Edge Autosport) from when I only had the GTX3071 turbocharger. Alan and I hope to fine tune this with the Cobb AP in the coming months.
I’m still using my trusty Hallman MBC- and it may be that I’m forced to go for a EBCS so as to control the power lower down. Not sure yet- but I think it will be difficult with the Hallman to get WOT (wide open throttle) readings necessary for tuning because of the increased wheel spin.

For those of you who are more techy on this stuff (I’m not!) and have read up on the 1980’s Lancia Delta etc, the boost pressure is not compounded/multiplied in this particular project- since the TRD supercharger is just a centrifugal one- and not a displacement pump- like an Eaton type. Infact- I’m not exactly sure what the technical effect is (I know that sound hilarious!) on the pressure between the s/charger and the turbo and have not measured the psi between the two. It must however at least reduce the “differential” load on the GTX3071 turbo - making it easier to spool. All I know is that it seems to work really well.
This was a lot of work for me- and the first time I’d attempted such a thing. I did it over a 7 month period in my spare time. The car is a daily driver (you’ll note the Miata 16’ wheels and regular tires- my wife didn’t like the low profiles!!)- So I decided to divide up the project in such a way (four parts) that the car remained drivable- and in fact was only off the road during the week of fabricating the brackets.

I’m not advocating for this conversion and don’t intend to do a more detailed description. It was an idea that intrigued me after reading the Wikipedia article on the Lancia Delta- and I had no certain evidence that it would even work on the Speed 3 and I had no Mazda pattern to follow. It brought me a lot of pleasure to do something different and pioneering and also the results brought much satisfaction. Hope that this write up is of interest to fellow enthusiasts.




Thanks to Alan Jackson from Edge Autosports for his idea bouncing and for putting this article on the forum.


Tim Clark. Tyler TX