Power for Pennies: Boosted Edition

"Bozi Tatarevic" (hoonable) 09/02/2014 at 10:04 • Filed to: None

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There are many ways to raise power and before exploring !!!error: Indecipherable SUB-paragraph formatting!!! the flavor of the day was turbocharging. There are many pre-made kits available for popular enthusiast cars out on the market that provide a complete package at a cost. Our goal was to think outside the box and make power with the best bang for the buck. This required some research but gives us the same end result at a fraction of the cost.

Power Goals

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The first step in planning any turbo setup is to set goals for the power you want to make and the range of RPM's where you want to see that power boost. The best way to go about this is to look at the efficiency of the engine you are boosting and compare it to a compressor map of possible turbos. There are many great articles on how to read a compressor map like the one !!!error: Indecipherable SUB-paragraph formatting!!! to learn how to read a compressor map and size a turbo. Once you have sized the turbo, then it is time to see whats available on the market.

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Choosing a Turbocharger

There are many inexpensive OEM turbochargers that provide the same power as aftermarket turbochargers that are used for turbo kits and can be found online for very good prices. In our example, we will take two vehicles, a Mazda Miata with an I4 1.8L engine and a Lexus IS300 with an I6 3.0L engine. These will not be detailed builds for each but general examples of how the results were achieved. Based on the size and efficiency of the engines, many turbo kits for the Miata used a Garrett GT30R turbocharger, while the IS300 saw kits with the GT40R turbocharger. After doing some research we find that OEM equivalent turbochargers for the GT30R include the Holset HX35 and the Borg Warner S252 while a comparable turbocharger for the GT40R is a Holset HX40.

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The Borg Warner is used in many applications and for our project we found the S252 on a John Deere diesel engine. The S252 on the Deere engine has the same compressor cover and bearing cartridge as their performance version but a larger T4 exhaust housing. We found the Deere turbo for $160 as a new take off. To resolve our exhaust housing situation we turned to Bullseye Power who make custom housings for these turbos and bought a 0.55 A/R T3 housing for $225. This brough the total cost for the miata turbocharger to $390.

The Holset HX40 was found on an online diesel forum and was a rebuilt version that was purchased for $425. The turbo came with a T4 housing that was well matched to the 3 liter engine in the IS300.

Choosing a Manifold

Once the turbocharger is selected you need a manifold to be able to mount it to the engine. For the Miata we chose to purchase an exhaust head flange, the T3 flange, some tubing and used the wastegate flange that came with our wastegate. Total cost for all of these parts was around $220 and we welded it up to form the manifold. For the IS300, we purchased a manifold and downpipe combo on ebay for $300 that is commonly used on the IS300 NA-T kits.

Exhaust

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The next piece in the turbocharger setup is connecting the turbocharger to the rest of your exhaust. For the miata, a downpipe flange was purchased for $20 and various 3in pipe sections were purchased at the local metal recycling yard for $80 and an exhaust was welded up to go to a $65 Magnaflow muffler. On the IS300 the 4in downpipe was stepped down to 3.5in with a $30 adapter and the rest of the pipe was acquired from them recycler for $75 and finished of with a $90 Magnaflow muffler.

Wastegate

The remaining piece on the exhaust is the wastegate. Both vehicles received a Tial wastegate with the Miata using a 38mm that was purchased for $219 through a forum special and the IS300 receiving a 44mm model that was purchased used for $180.

Intercooling

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For the intercoolers we turned to ebay. There are any number of kits and Intercoolers that are available online and for the Miata we chose 2.5in thick core and used a universal piping kit to complete it. Total cost was around $220. The same was done on the IS300 but with a larger 3in core and total cost was around $280.

Fuel

For the Miata, the fuel system was comprised of 550CC RX7 injectors ($70) and a Subaru Legacy GT 195lph fuel pump ($15). For the IS300, we used Denso Supra TT fuel pump ($137) and Subaru WRX 425cc injectors ($65).

Engine Management

On the Miata, we used a Megasquirt 2 EMS ($400) and on the IS300 we used an AEM FIC ($275) both were purchased through forums sources. We wired each of them up to the car and used base maps available online to start the tuning. We alter completed our tuning on the dyno.

Misc

There were some miscellaneous parts including various fittings and hoses and so on that added up to around $200 for each car

Results

The Miata cost was around $1800 and running at 10psi the vehicle put down 250 horsepower to the wheels which is a huge improvement over the 100hp stock number. The IS300 cost was around $2000 and running at 6 psi put down 305 horsepower and that is a 123hp improvement over the stock dynop of 181hp. Both of these kits are very basic and were used as a base for further modification which included upgrades to the engine and transmission in order to run higher boost levels and really make these turbo's shine.

Check out more in the series:

Power for Pennies: How To Score a 500HP LS Engine for FREE

Power for Pennies: Build a 400hp Chevy LS Motor for Under $1200

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Power for Pennies: The Low Cost 2JZ Swap

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Aya, Almost Has A Cosmo With Toyota Engine Owned by a BMW. > Bozi Tatarevic 09/02/2014 at 10:14

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Bozi! It's always amazing to read your post man!

Anyway, i used to have a Toyota Crown with 2JZ-GE underneath, same with the supra non turbo i think. Can i use the kit from the Supra TT Instead, or following your IS300 route?

claramag, Mustaco Master > Bozi Tatarevic 09/02/2014 at 10:15

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aaaaaand bookmarked. Great write up, gonna dig deep into this later tonight

TheRallyStache > Bozi Tatarevic 09/02/2014 at 10:15

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So you guys were running stock CR I'm assuming?

Bozi Tatarevic > TheRallyStache 09/02/2014 at 10:26

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Initially had stock CR on both. The IS got a thicker head gasket later on to lower the CR but was unfortunately totalled before going any further. The Miata was swapped for a V8 so no additional changes were made.

Bozi Tatarevic > Aya, Almost Has A Cosmo With Toyota Engine Owned by a BMW. 09/02/2014 at 10:27

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You can use either. The biggest external difference is the intake manifold and you may have an ABS block in the way of the turbo on the Crown.

TheRallyStache > Bozi Tatarevic 09/02/2014 at 10:29

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I've heard of using thick HG's as a cheaper and less time consuming alternative for making an engine boost-friendly. Did the IS300 originally come with a composite or MLS HG?

shinsen > Bozi Tatarevic 09/02/2014 at 10:36

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what am I looking at? -NA car owner

Aya, Almost Has A Cosmo With Toyota Engine Owned by a BMW. > Bozi Tatarevic 09/02/2014 at 10:40

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Yeah, i've seen the one on the Supra and it's quite different.

And oh, Let's say i want a bit more power than your IS setup, like 380-390hp, how much boost that i'll need?