Small Turbos?
 

Hi guys, first post here. :happyanim:

I don't have a BRZ/FR-S, but I've been researching them quite a bit lately.
I used to have a 1996 Miata which I turbo'd, and Miata people including myself seemed to use a lot smaller turbos.

I had a GT2554R (actually from an AVO kit my dad and I previously installed on his Impreza 2.5TS) on my 1.8L Miata and enjoyed instant boost from about 1800rpm and up with ~220 whp vs 120 stock.
It seems like no one is offering below a T3/T4 50 trim for these cars. The Miata head was way older technology so I'm sure the FA20 head flows way better which should help spooling earlier. I admit I don't know much about T3 sized turbos, would a 50 trim give good torque by 2000-2500 rpms?

Also, are T3/T4's only oil cooled? Are people installing turbo timers? It was nice having water cooled with the GT2554.

Look at full blown for the gt25 and ft28 series. I know they base there kits off the t2 frame. There is also treadstone using the smaller borgwarner efr series turbos that are similar to the t2 frame turbos. I have not investigated all the turbo options to see if the fa20club kit has a t2 offering. As well there are a couple other kits on the market that may have smaller turbo options.

A good number of kits are running GT28's as well, which are relatively small.

I have a GTX28, but spool is still not until 4k. If you're looking for moderate power down low, you may just be better off with a supercharger

I got a gt28 that is water cooled

are you sure you don't have a boost leak? i'm only running 7psi, but i hit it at barely above 3k. making boost by 2.5k usually, maybe lower.

Looks like the greddy kit's turbo is relatively small right?

With a redline of 7400 or more, you wouldn't want something too small. What is the redline on that miata?

Till this engine has some good long term durability testing on it, would want to keep out of boost during most the my daily driving.

It seems perfectly reasonable to have the boost come on at 3.5 - 4K. You don't need to be in boost any lower really as you're probably just puttin around town. Why waste the gas and put extra wear and tear on the engine?

There is a company in South FL building a kit with a TINY Turbo, I believe they are called Olympic Motorsports, I believe its similar to what you are looking for.

Boost won't develop unless you are on the throttle, so there won't be extra wear and tear while "puttin around town."

its not surprising that the early turbo kits employ large turbos.....which make the classic 45' increasing torque curve once the boost hits fairly high in the rpm.....just like classic Supras that made silly HP..... When torque and HP both spike quickly in upper midrange will make the car VERY lousy on the street......

Smaller turbos that spool quickly (or twin screw superchargers) offer near instant boost across the entire power band....BUT at the price of peak power.....but for a street car a smaller turbo that can achieve full boost from say 2000rpm up is much better than one that is worse than stock below 4k..... race cars are different of course.... My opinion as a racer.....I would rather have a 200hp-200ftlb engine that has a wide flat torque band (like our cars do stock) than a 250hp-150ftlb engine that has it all up high.....why? getting off the corners.....high torque engines always win the beginning of the drag race off the corner....then high RPM or high boost engines eventually might catch up if the straight is long enough, but have to take risks in the braking zone (easy to block) to make a pass..... plus mini straights inbetween corners always favor higher torque

It doesn't take much throttle at all to get into boost on a gt/gtx28. My mileage in the city is around 20-22mpg, where I get 33+ on the highway.

No leaks. Tuned at Full Blown. 16 psi and it hits right around 4k

oh. well that's a lot more boost than i'm running lol.