Should I consider getting a smaller turbo?

[Audiomaker]

Hi all,

I've had my 2002 T-Busa for a few months now and I'm beginning to get a feel for what it means to have a Turbo on this bike.

I have a conservative tune on the bike. It dyno'd at 220hp. To me, this is still very fast.

Currently, the bike runs normally at WOT until I hit about 6500rpm and then holy-moses! Hang On! (to me anyway).

However, I am not impressed with the power in the lower RPM ranges. I suppose I'm used to it, and I don't like to wind the bike so high in the city to get into boost that quite frankly I need to back off of almost as soon as it comes on.

I am looking for more linear performance... I guess more like one would expect from a supercharger. More power in the city with less surprise at the top.

What I currently have is a T3/T4. Sorry but I really don't know much about turbo models, but that's what's in there.

The bike was built for 350hp on C16. I have a 7 lb spring in there instead of the 14 that was originally on the bike.

I was browsing the threads and saw someone post that they ran a Garrett GT2871R and that it would spool at 3500rpm and be at full boost by 5000rpm. I like the sound of that or something similar.

My target HP is 300 on race gas until I get an intercooler and then my target will be 300hp on pump gas. I really don't see myself needing more than this in a commuter and keep in mind that this is still less hp than the bike had when I purchased it. Frankly the 220hp that it has is quite enough. I'm just allowing for "expansion" down the road with these projections.

So what is the quick road to getting more horsepower sooner (asap) with an eventual theoretical target of 300hp starting from where I'm at now?

Please be specific in model #s and parts as your advice might be what I apply my wallet to, and let me know what obstacles I'll be looking at to make the swap.

Many Many Thanks
Sean

 

[OZBooster]

You may be able to speed up the process with a smaller A/R exhaust housing , it will increase the velocity of the exhaust gasses before they hit the exhaust wheel
yours may have the a/r cast onto the housing , otherwise its often cast into the ex housing entry just inside the flange
common numbers are .48, .63,.7x, .84, .96 and bigger , yours probably is a .63
2871 will come on like a light switch , i have used the 28 series but prefer a 30 now ,

 

[Audiomaker]

Thanks OZBooster.

Could you describe in more detail what "2871 will come on like a light switch" means in terms of how it performed and felt to ride, and also explain why you prefer the T3 now?

I'm trying to get a "feel" for it without actually having an example bike to ride, and without installing one.

Thanks!
Sean

 

[OZBooster]

its a sharper , quicker response, lifts the front tire or blows off the rear rather than giving drive
it can be a lot of fun too, suppose its a personal peference , i live in open country and like my current gt30 on my streetbike much more than the first turbo i did with gt28, and another wih 2871,
my race busa has a gt35 and i know i would not like it for my style riding on the street