So, looking to replace my turbo. Currently it is a precision 5831 0.63 a/r trubine housing.
The 5831 seemed to have a bit more lag than I might like. I mean its still fun the top end, and for highway pulls its a blast!
But I kind of want to try something that is going to be more "fun" streetable. Less lag. Ive been eyeing the GTX3071R.
Im noticing that is has a smaller compressor wheel than the 5831. Not sure how much the compressor wheel is going to determine lag?
How much would I sacrifice top end to get less lag. I dont want it to just fall on its face at the top end. And if that is the case, Id rather deal with lag.
Also, Im not sure which a/r exhaust housing to get. Suggestions? Im pretty dumb about about turbo specs, but not ENTIRELY dumb.
I mean I know that a small a/r turbine will give faster spool, but just looking for suggestions on which to get. With the smaller compressor wheel, should I be able to get away with a larger a/r? Would 1.06 just be stupidly too large?
Oh btw, Ill be using t3 inlet housing, so my options are 0.63, 0.82, 1.06
Im also open to other turbo suggestions as well, but I do know I dont want a precision turbo.
Power wise, Im pretty much just street driving this thing now, but I would like potential to make roughly 500whp in the future if I wanted. Im not dead set on this number though.
Setup:
B16A sleeved. About stock bore.
Manley Rods
CP 9:1 pistons
Valve Springs and Retainers (Rev cut set to 8500)
Edelbrock Victor X IM
Log turbo mani.

Im sure I forgot something, so ask me for any details I left out. Thanks!

 

If you're already running .63 and find THAT too laggy, you need a new manifold.

 

So is a/r turbine size the biggest factor for turbo lag?
Will the difference in compressor wheel size not have much of an affect?
Also,what about the differences in the turbine wheel dimensions?

GTX 3071
Compressor
Inducer 54m
Exducer 71mm

Turbine
Inducer 60mm
Exducer 55mm

Precision 8531
Compressor
Inducer 58.16mm
Exducer 74.93mm

Turbine
Inducer 65mm
Exducer 56.59mm

 

The exhaust housing has a lot to do with responsiveness. Usually, the larger the exhaust A/R, the laggier your turbo would be, and wheel trims also have a role there. There are those here that could explain this relationship WAAYY better than I can. Lol

 

What kind of HP/TQ are you making currently? I’m no expert, but I couldn’t imagine stepping to a larger AR would give you a quicker spool. I always thought the larger your AR, the more it could breath up top while sacrificing a bit down low. Is your turbo now JB or BB?

 

Sounds like a GTX3071R in a 0.63 is the right fit for you. Bear in mind that a 9:1 compression B16 is always going to be laggy. Lower compression, a short stoke and small displacement are all factors that create "lag" or more specifically boost onset point - its simply a matter of physics. A turbo B16's powerband is 5500 - 9000 rpm. If you want that low-end torque and fast response, then a B18 sub assembly is the way to go rather than chasing different turbo combinations.

You could also look into something like a Garrett G25-660 but those are big $ turbos - you pay for the latest technology. That will be the closest to offering fast-spool and 500whp capability.

 

It will be quicker spooling yes with .63.
With .82 it will be the same probably.
The t3/t04e 57trim in .63 is deffiately not a laggy turbo

Id get a good mani before changing turbo really because yourll be loosing power on log ultimately requiring to go bigger turbo to hit the same target(...)
Whats your budget for everything?

 

Dont be too harsh, but this turbo was never dynoed (I know I know). The setup was previously dynoed with a different manifold and turbo. I dont remember specs on the dynoed turbo, but it had a 61mm inducer on the compressor wheel. This setup made 350whp (pump gas) and 470whp (race gas).
The precision turbo is roughly the same size as my old turbo and my AF is solid (I know I know).
Also, I do realize that a larger AR apples to apples is not going to give me faster spool. What Im wondering, comparing the Precision 5831 .63 ar to the GTX3071R, is the whole design and size difference of the turbo so different that for example 1.06 ar on the GTX701R would give similar spool the 0.63 ar on the 5831.

Excellent info right here. Exactly the kind of info I was looking for. Sound like Im always going to have that "lag" unless I go really small hu? And then my top end will suffer quite a bit I would guess. Im not terribly annoyed by the lack of low end, just thinking about trying something different.
G25-660 I just looked it up and its actually only about another 200 bucks compared to the GTX3071R. How ever it looks like I would have to buy a new manifold. It only comes in T25 and V-band turbine inlent housing? Unless Im looking at it wrong. My manifold is T3. I might have to just go all our and get a new manifold too. What's another $1k when already spending $2k? lol

I dont really have a budget. Also, my precision turbo is broke is the reason I am changing it. So its not about upgrading for more power or anything like that.
Im just thinking/researching about what I want to do. Cheapest easiest solution is to just buy a new precision replacement turbo that bolts right in. No cutting or welding new DP or anything like that.
Does anyone have any good ideas for something that would be a direct bolt replacement (turbine housing wise) for my precision 5 bolt turbo? I dont want to risk buying another 5 bolt and then realizing that it positions everything slightly different and then I have to cut up and weld the DP. If I know I have to cut up and weld the DP, id prefer to go ahead and switch over to a v-band outlet.

Thanks everyone for you responses.

 

You do get a T3 G25 : https://www.atpturbo.com/mm5/merchan...ry_Code=G25660

5-bolt GTX3071 Gen 2: https://www.atpturbo.com/mm5/merchan...de=GG2-3071-T3

Also PM @TheShodan and checkout his turbo creations here: TR3030R "VelociRaptor" turbocharger - Cartridge & Cover
Banshee T04B Ball-Bearing Super Core

 

Hey man, again awesome info!!! I'll look into these. Love that I can get the G25 in T3. I see that it only has a 0.92 ar option. How do you think that would spool compared to the Precision 5831 I have?
So I guess these companies will take a garret turbo and then cast their own turbine housing? Or mill their own compressor wheels? I never realized that. Like I said in my first post, I am kind of dumb about turbos and selection and stuff.
Once again thanks!

 

G25-550 at .92 is a very good turbo. But to hit that 500 to the tyre youll need a mini ram or if even better if you have a welder nearby search and copy the mini-EQ manifold.
That with a .92 (better get vband version if youre getting a manifold).
If you really want every last bit of spool and easier 500whp with a maybe 550whp (on higher octane-special nights ) you can get the G25-660 with the T4 internaly gated twin scroll turbine housing 877895-5012S but youll need a divided turbo manifold too.
If you like the idea of divided/twin scroll setup there is the EFR7163 also on t4 internaly gated turbine housing (11639880002) and thats the best 550-600 hp out there. But all these are expensive options...
If you keep the log mani 500whp with the g25 will need watermeth injection oe E85 and thats still a maybe. Also you must have a good sized intercooler too and some tuner1 or itr cams.
High hp on s small turbo requires everything to be good and efficient. Its difficult cost wise but it comes with the fruit of quick happy spooling setup. You can have 500 to the wheel with a bad manifold oem b16 cams bad intercooler bad tune on 88 fuel easy, with a...
G42