Back in the day I followed the progression of modified stock turbos as Buschur and others started coming out with them. . . then updating them. . . then updating/improving again . . . etc. On my old EVO 8 I had the stock turbo, then an Evo 9 turbo, then a Buschur 20G, and then finally the Buschur 20G-LT which soon became known as the Forced Performance Evo Green. When I sold the EVO 8 a few years back and decided to build an EVO 9 I kept the Green for the new build. It served me well over the years - Two Solo2 National Championships, 10.9 second quarter mile passes, lots of National Tour and ProSolo wins, etc. In fact it was the only Non-HTA Green on the Fastest Stock Appearing Turbo list for 2010. Anyway, over the past couple years I've been watching the further stock-style turbo advancements just waiting for the perfect turbo to come along. I can gladly say that I believe I have found that
"Perfect Turbo" -
The CBRD BBK FULL!
MY NEEDS: Everyone has different needs, so the "Perfect Turbo" would be different for every individual. I need a turbo that will
excel at autocross, be great at road racing, and be capable of 10 second runs at the drag strip.
Autocross - To excel at autocross the turbo must have near-instantaneous spool, quick boost recovery when off then back on the gas, and make as FAT of powerband as possible.
Road Racing - Turbo should not have excessive lag. A 42R would probably not be fun for very long on a road course
One other "NEED" here is a turbo that is smooth and does not have compressor surge/BOV bucking issues so you can be smooth on throttle inputs. More on this below.
Drag Racing - With a properly set up and driven car you can hit 10's with any of the stock variant turbos. More power just makes it easier to do it consistently or with a less-highly modified car.
RESULTS: The CBRD BBK has been on the car now about 3 weeks and 4000 miles. We ran the 2011 Cannonball One Lap of America race 2 weeks ago. It consisted of 2 drag events, 2 autocross events, and 14 road course events, so I got a pretty good feel for how the turbo is performing. After all that - I am 100% positive that I picked the "Perfect Turbo" available for my needs!
Autocross - Back when the FP Green first came out it was the best turbo choice for autocross, IMHO. Well, the BBK kicks its butt in every category. It spools up faster, has quicker boost recovery, makes a TON more top end power, and has better driveability as far as surging/BOV flutter goes. This thing is full of WIN!
(the Street Mod Solo2 National Champ for 2010 was running the BBK-Full) Back when I had stock gearing the Green seemed to spool up very quickly with almost no lag. After I switched to the HKS 4.11 final drive gear to get more top-end speed in 2nd gear there was a noticeable increase in spool time coming out of tight corners. There was now a slight delay from the time you went full throttle until you got full power. NOT ANY MORE!
The BBK Full drives more like a V8 engine. Transient response is awesome! It is also very "linear". It feels like if you give it 25% throttle you get 25% power. Give 75% throttle and you get 75% power. I think it makes the car much more predictible and easier to drive.
Road Racing - to get full power on the Green we had to run higher boost, but the stock BOV would not hold that boost so we had to run a different valve that caused a lot of surging. Undriveable on the road course. The stock valve seems to hold just fine with the BBK so far, so I should be able to run more power with the BBK on the road course than I was able to on the Green. The boost spike is not as high, so it doesn't blow the valve open, but the BBK hold much MORE boost on the top end (tapers much less). With the quicker transient response and the stronger top end the car should be just plain faster all around. I have not run a track yet with the BBK that I've run on before with the Green, so direct comparisons will be forthcoming as I visit my regular tracks later this year. The car so far feels AMAZING.
Drag Racing - I ran a 10.9 with the Green last year. The BBK makes more power all through the powerband with a TON more power up top - so common sense dictates that it should be good for at least a couple more tenths.