mxt_77

I did a quick search, and of course perused the existing FAQs, but I didn't see an existing thread dedicated solely to providing a guideline for picking the the right turbo for a specific application. I don't have any knowledge to offer, but I'll start a list of questions whose answers I think would be useful in choosing the right turbo. My goal with this thread is to address specifically turbo selection questions/criteria... not getting into "turbo kits", "intercoolers" (unless a discussion is necessary regarding their effects on flow, charge temps, power, etc), or anything else that is not directly related to the turbo itself.

1) Turbo terminology:

• Compressor Trim?
• Turbine Trim?
• A/R?
• Turbo naming conventions? GT35R? T3/T04? T60-1?
• etc.

2) How do I read a compressor map? (What is a compressor map?)
3) Once I know how to read a compressor map, how do I determine how that compressor will work with my engine? (I assume that some sort of flow maps from a stock and/or modified head/motor will be necessary here.)
4) For my engine, how do I determine how much boost a given turbo will generate at a specific RPM? (maybe this will be answered by #3, or a combination of #2 & #3).
5) Turbo options/upgrades:

• Ball-bearings- pros & cons.
• VNT- How does it work? Any aftermarket applications available?

6) Turbo housing sizes? What fits in an S2000 engine bay?

No need to plagiarize... if there's a source (including specific- and concise- S2Ki posts/threads) that already has all this laid out in layman's terms, then just provide a link. Otherwise, hopefully we can start a useful discussion here, and have it linked from the FI FAQ sticky.

Here's hoping that this thread becomes a valuable resource!

Erick S

Subscribing..

Erick

Scorpion

1. Trim, both compressor and exhaust : Trim is an area ratio between the inducer and exducer, inducer being the area of the wheel at brings in the air (small on compressor, large on turbine) and the exducer is the part of the wheel that kicks the air out (large on the compressor, small on the turbine). To find the trim of a given wheel, divide the inducer quared by the exducer squared and then multiply by 100. Easy huhhh

A/R : Stands for Area/Radius. "the inlet (or, for compressor housings, the discharge) cross-sectional area divided by the radius from the turbo centerline to the centroid of that area"

quote from www.turbobygarrett.com, where you can find every answer you need btw

With turbine housings the larger the A/R the longer the spool up but the more top end the turbo can provide. The smaller the A/R the faster the spool up but top end will suffer due to backpressure in the housing.

Turbo naming. This one's all over the place. You will have to go to the turbo manufactures site to get specifics. Most Garret turbos are easy though. GT3082R for instance. GT is the series turbo, 30 is the turbine size (not sure in what referance but the higher the number the bigger the turbine wheel), the 82 is the exducer size in mm on the compressor and the R means it's ball-bearing. A GT4088, again GT is the series, 40 is the turbine size (bigger than a 30 or 35) and has a 88mm exducer. Not having the R means it's a journal bearing turbo.

2. Compressor maps. The down and dirty.

Two axis, vertical is pressure ratio, and horizontal is the flow rate of the wheel. When looking at the pressure ratio remember that it's in BAR, and read in absolute, Meaning that 1Bar is atmosphereic pressure.

So how do you read it? Take the amount of HP you want to make. Say 450HP on a S2000. (remember we are talking crank HP not wheel). So you are looking for a turbo that can flow atleast 45lbs/hr of air (rule of thumb is 10hp per lbs/hr air). The figure out how much boost it will take to get you there. On average, the S2000 makes 15HP per psi of boost. Manifold design, charge piping size, intercooler efficantcy all play into effect there, but 15hp is a good start. So if the S2000 makes 240 in stock form we need an extra 210hp. At 15psi we'd need around 14psi of boost, or 1 bar. Add taht to the atmoshpereic pressure and we need 2 bars worth of boost on the map. So 2 bars, 45lbs/hr of air. Now find a turbo look at the map, plot that point and see if it's in an efficant area of the map. If it is that turbo will work for you. If not, find another turbo.


That's all for now, I'll post more after I eat And I'm sure there are alot of typos in here, I'll clean that up later too

Soul Coughing

you just explained alot of questions i had as well... thank you soo very much!

timg

http://www.turbobygarrett.com/turbobygarre...ech_center.html
It's all here.

If you google it, the Buick GN guys and a few other sites have great turbo primers.

Tim

GyozA

Thank you. This is VERY helpful. =D

Faboo

Here is another FAQ at Turbomustangs.com they even have a downloadable PDF file so you can always have it on ur computer....more info than any one can read including a good list of turbo compressor maps, detailed pictures/illustrations and it is not mustang specific when talking about flow and what not..

PDF file

Turbo Bible

Erick S

Thanks for the information! This is a very resourceful post and one of the reasons this site is so helpful..

Erick

s2kpilot01

+1

NFRTurboTerror

This has answered alot of the questions i had about turbos also, but i never asked.