need some help picking a turbo

So ive done lots of reserch and I know all the basics of turbo charging a motor, but for the life of me cant decide on what turbo to run on my setup(I.E. t3/t4, turbine and compressor sizes)

the motor being boosted is a b18a1, stock internals with arp head studs.

Im looking for something that spools quik(inbetween 2000-3500rpm) and will push up to 15-20lbs at a redline of 8500 for when I build up the LS-V in the garage. Is this even going to be possible to fit my wants or should I start rethinking it?

im looking for some insight from some of you turbo gurus, so what do you guys got for me:read:

did you look at manifold design yet? i would start there before you start looking at turbo specs. for the most part the faster spooling manifolds, log or cast, often choke on the top end. most people dont notice it, as they have no real clue what a fully usable power band feels like. for that low of spool, regardless of your manifold, i would suggest a BB.

also… look at the link in the quote below…

[QUOTE=90DB1T;2089080]plot the turbo based on the compressor map. here is a good link if you dont know how to do it:[/QUOTE]

Mrpenny is making me a mani, over the last hour or so weve decided a log would be best until I decide to upgrade at a later date.

thanks for the link, I will be sure to take a good look at it

im also looking at this link. specifly post number 14 on doing the math involved in finding a properly sized turbo.

the info is the same in the link i provided… just dumbed down for those that havent done it before.

after closer examination, I did see that.

So after doing the math @15 lbs of boost I came up with these numbers.

Airflow/Thrt %----LB/MIN----CFM’s

Ive been looking at different compressor maps all morning and after ploting all the points, it looks like a gt28(discus potato turbo) looks like it might fit the bill perfectly, all my plot points are on the map and at full throtle, the turbo should be at about 75% efficency

one more thing to point out is these number are based at sea level, being im in denver. A mile above sea level. Im sure these numbers are going to change a little bit. Ive been searching through threads on H-T all day and there are plenty that talk about the affects of altitude change on boost presure, but nothing about the conversion factor needed when picking a turbo, :frowning: so Im gonna dig around on high altitude imports site for a little bit and if push comes to shove call servion and see what he says

Last but deffinatly not least is trying to decide what A/R ratios to go with, any insight on that?

aslo anyone care to add there experiences with the GT28?

in my experience, driving cross country with a boosted ej6 using hwy 80, the turbo will simply take a bit longer to make boost. this is obvious, since the air is simply thinner. small side effect is that at the lower end of the rpm band the turbo might be a slight choke on the intake tract. nothing major and can be tuned out. but something you might look into when doing up your base map.

as far as a/r… well this will tell you when your going to spool and how the turbo will react after x amount of rpm. this can also be plotted. same link i showed :wink:

the gt28 is a very very good street turbo. its not a uber high whp supporting turbo. however it spools very quickly. a buddy had one on his 1.8L (5-valve) audi wagon, those two made sweet sweet love to each other. at the top of the rpm band though, it was a little bit of a power drop off as the turbo couldnt keep up. but that engine pretty efficient. i think a gt28 would be near perfect with any of the honda non-vtec engines.

So do you think that im overthinking the high altitude issue and making it a bigger issue than it realy needs to be and not worry so much about it?

As far as A/R ratios go, im only finding a single ratio that comes with that turbo, so im not to concerned with that anymore.

its an issue… but not really for the builder. more for the tuner.

GT28 is THE turbo to go with for street and spool up. i dont know if you remember my thread but i made 300whp 292ft-lbs with a GT2871R with the .64 a/r exhaust housing with only arp headstuds. i would take the gt2871r over the gt2860rs since it will give you a little more room for power later on.

ill try to scan my dyno graph to show you how the gt28 reacts to a stock b18a.

so there are different a/r trims, thanks man

the GT2871R has two exhaust housing a/r, the GT2860R has a couple variations, and the GT2860RS has two different exhaust housings(same turbine as the GT2871R with .64 and .86 a/r)

word, ill look into that a little more. thanks for the insight:up:

Thanks for the advice guys!

GT28xxRS, :rockon:

HAHA, thanks for the imput man. sadly I havent had the time to look into this further due to me spending it trying to figgure out my dataloging problem:(

ill try and keep this updated with any info I find to be important to this in order to help anyone else down the line:up:

hope you dont mind dude just posting this for a little encouragement.:rockon:

HAHA, thats doing the trick man.

Question, will I still be able to run my full fluidyne radiator with this turbo or am I going to have to run a half rad?

depends on the manifold. in my setup it’s only my wastegate that’s in the way. my fabricator could of put it somewhere else if i wanted to run a full rad but i brought my car in with the half rad so that’s what i got.

good to know, as stated above im getting a custom mani made, and im debating about buying an ATP aftermarket turbine housing that has the W/G flange right on it just to eliminate any chance of boost creep
second to botom

what kind of manifold design did you have in mind??as long as your wastegate is placed where all the runners meet you’ll have no problem.

also make sure that you’d be able to keep your full rad with that turbine housing. with that housing your turbo will be way further away from the block. usually to keep your full rad you need to run the wastegate on the side.