Turbos -- read this before posting

shiftless

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The reason I posted this thread originally was because I was tired of newbies with no clue coming on here asking a bunch of questions about turbos. They dream about it for a couple weeks, maybe even buy a couple parts, then that's where the project ends. So if you fit this description, please don't ask about turbos on here. The topic of turbos is restricted on this board to a) those with the resources, ambition, and follow-through to actually pull it off, or to b) anyone knowledgeable in the area who wishes to help out and share knowledge with the folks in group A. By request, I unlocked this sticky thread so that folks can post up helpful and useful information about turbos. So have at it!  :thumbup:
 

Chevalade™

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Junkyard Turbos:

TV81 Series: 8101, 8102, 8115, etc.

Map for TV8101 (dont mind the plotting already done, it was for a 454)


This turbo is good for about 125 lbs/min of air. Or in other words it is capable of around 800-1000 hp. Good for a single setup on either a 425/472/500. They can usually be had for arounf $200 for one needing rebuild or $7-800 for a rebuilt one. They come with a few different turbine housings, 1.39, 1.6 and 1.84. The last would spool too slow for our application, the first would spool in the 27-2800 range and the 1.6 should spool around the 32-3500 range.
 

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Chevalade™

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New Turbos

S400 - Can be had for less than $600.

There are a few different types of inlet compressor wheels for the S400, the map below is for the S475 or the smallest one they have. These turbos are capable of 1000hp per turbo. They have turbine housings 1.10, 1.32, and rumor of a .96. These turbos are said to be comparable to the TV8101. These could be used in a high hp twin setup, or as a single unit.

Map:
 

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dave brode

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shiftless,

I suggest a post suggesting that turbo newbies buy the books I list below and STUDY before posting. Imo, they should understand the terms compressor pressure ratio, surge, A/R and others.

The books:

The old book "Turbochargers!" by Macinnes is good. The newer "Street Turbocharging" by Warner is good too [both HP books available from Summit, Jegs, any book store etc]. Imo, "Maximum Boost" by Bell is *ok*, but was more of an advertisement for his Miata turbo kits imo.

I assume that you can juggle posts around in a thread, combine posts, delete posts etc. If so, and you choose to, you could let the thread go a bit, then clean it up somehow.

Thanks,
Dave
 

dave brode

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Here's a link to maps for some common compressors. You must click the compressor map button. Note - this site is a dealer's site, not the Turbonetics Corporate site.

http://64.225.76.178/main.htm

Here is a couple of pages from the Macinnes book from a book review. Included are turbo "sizing" charts for various boost levels and engine sizes using Rajay and Garrett [called rotomaster in these tables] [see tables 3 through 7]

http://books.google.com/books?id=pewyJ3 ... do#PPP1,M1
 

shiftless

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Dave, I agree, I'd also say that turbo newbies need to learn what a compressor map is and how to read one. The compressor map describes the capabilities of the turbo's compressor; how much air it can flow, at what pressure ratio**, and at what efficiency. Therefore you can use it to calculate if a particular turbo will work well, rather than guessing. There are many compressor maps floating about the internet and more can be had by simply emailing the turbo manufacturer and asking.

Here is a neat tool that helps you plot points on various turbo compressor maps:

http://www.not2fast.com/turbo/glossary/turbo_calc.shtml


** pressure ratio = ratio of absolute output pressure to absolute input pressure. Atmospheric pressure, 14.7 psi at sea level, is an absolute pressure. If the turbo is outputting 15 psi of boost, that's 14.7 + 15 = 29.7 psi absolute output pressure, divided by 14.7 psi absolute input pressure (assuming ZERO air filter restriction) equals a pressure ratio of 2.02. Study this subject a little more to get a firmer grasp on it, because it's important.
 

dave brode

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shiftless,

Good stuff.

Now, it seems to me that if we have the compressor map, it's easy to figure how it [or they] will work on our engines. The turbine side is another subject. On the diesel turbos, we aren't compairing apples to oranges, since the diesels operate in a much different rpm range. So, my point is, sizing info for esp the turbine side diesel turbos on a gas engine would be most helpfull.

--
To me, it's simple realizing how a pair or even 4 smaller turbos from gas engines will act on our engines. Example, although probably not a logical one, but perhaps it'll make folks understand:

Take 4 Garrett T3 turbos from old 2.2 mopars. The worked fairly well on a 2.2, supplying perhaps 250 horse worth of air at a sane boost level . The turbine sides were chosen so they'd do ok to say 5500. So, 4 of them would act pretty much the same on an 8.8 engine.

Another example:

A pair of '86/'87 GN [231"] turbos. Apx 350 horse of air each and turbines sized for 5000 or so on a 231". Since 231 x 2 = 462, they would give 700 horse worth of air, but the turbine sides would "act" a little differently on a 500". Although the turbine side allowed 5000 or so on a 231, a pair of them might choke a 500" much sooner [or get into boost creep if the wastegates could not bypass enough volume].

Dave
 

dave brode

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On the deisel turbos:

From the few maps I've seen, it looks like the compressors for diesel turbos are most efficient at much higher boost levels than a gas engine would normally see. Maybe not a big issue, but my point is, compressors from at least some deisel turbos may not be exactly ideal for a mild turbo'd gas app.

Dave 
 

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Here is a good write up I found.

I decided now would be the perfect time for everyone to learn how to properly read a Turbo Compressor map, and how to choose a proper Turbo for your vehicle.

Here we will show a compressor map for reference. (Bottom of post)



First off on the Y axis is the pressure ratio. This is atmospheric pressure, or 14.7 psi = 1.
The X axis is the air flow in pounds of air per minute or lbs/min .

To convert lbs/min into CFM you factor in the ambient air temp. Compressor maps use 27 degrees centigrade, or 300 kelvin (To calculate Kelvin, take celcius and add 273) One cubic foot of air at 300k weighs 0.07282 pounds. So, at 300k, convert pounds per minute to CFM by multiplying by 13.73.

Ok, now you decide how much boost you want to run. Take that amount of PSI, add it to 14.7 (atmospheric pressure) and divide by 14.7. Lets say you want to run 15psi.

Pressure Ratio = (15 + 14.7) / 14.7 = 2.02

Find 2.02 on the Y Axis. Draw a line straight across at this point.. Look at the range on the X Axis the line is passing through the turbo's efficiency range. In this example the range is from 15 lbs/min to 35lbs/min.

Now, you will need to find the displacement in cubic inches of your engine. You may know this in Litres or CCs, but CI is what we need for this excercise.

Now, VE is volumetric efficiency, this is just the measure for how much air your engine can ingest. For this write up I'm going to make up an engine for the sake of easier math. Most forums will be able to give you an estimated VE at 6000rpms, or the FSM. Believe it or not the math is too involved for even this writeup. So the made up engine is 2226CC or 136 cu in and at 6000 rpm and 90 percent VE ( .90):

CFM = Displacement in CI / 3456 * RPM * VE

6000 * 136 / 3456 * .9 = 212.5 CFM

Ok, so this looks pretty good comparing to our graph and early equation. BUT, this is just the amount of air the car will flow N/A. So if you do this math for a different engine and it doesn’t land in that range don’t concern yourself. To determine what it will do under boost, you have to determine what density ratio of the compressor and intercooling system will give you. To do that we need to take our boost point and determine how hot the compressor is going to make the air at that pressure level.

Temp(in F) = (((Tin (in F) + 460) * (Pressure Ratio0.283)) - 460)

For 15psi of boost at sea level at an ambient temp of 85F (85F = 300k or 27c)

Temp = (85 + 460) * 2.020^.283 - 460 = 205F

This assumes 100% efficiency. The compressor map tell us how efficient the compressor is going to be at a given pressure ratio and flow level. Since most of the map is at least 70% (.70) efficient or better (adjust this number for what range you're shooting for). Our true output temp is:

TrueT = T ideal / efficiency

For our example, 205F - 85F or 120F:

Actual = 120F / 0.70 = 171F

171F is how much the compressor is going to heat the air above the inlet temp. True outlet temp 256F.

Now, what happens at the IC? Pressure Drop, the Temp Drop. Lets assume a 65% efficiency from a small sidemount which isn’t the greatest, but let's face it, it is reality in alot of peoples situations(cough stinkfist cough). To figure out the intercooler efficiency and the pressure drop you would use: (IC = intercooler)

T IC drop = (T IC in - T ambient) * IC efficiency

T IC drop = (256 - 85) * 0.65 = 111F

The IC will drop the Intake temp by 111F, turning the 256F air into 145F air and dropping the pressure 0.5psi to 14.5psig.

Now we must figure the Density Ratio.

Density ratio= ((Tempin + 460) / (Tempout + 460)) * (Pressureout / Pressurein)

Density ratio = ((85+460)/(145+460))*(14.5+14.7)/14.7 = 1.79

Now with the previously figured 212.5 CFM value, we multiply that by the density ratio to get 380.1 CFM or 27.7 Lbs/min.

Keep going, we are getting there!

Now, draw a vertical line on the X Axis at 27.7 Lbs/min cross the original horizontal line from the pressure ratio. With a 40 trim wheel at 6000 rpm with the intercooler setup we calculated with, we are at 73 percent efficiency. Things could change due to your setup, that particular VE and I/C setup will not be the same for all engines, thats why all these values are dynamic.

Will the compressor be put into Surge with this setup? Surge happens when the turbo is too big for the motor. In this example with a 2.02 pressure ratio, the surge line is around 15 pounds per minute or 205 CFM. Let's assume the turbo is can spool by 3500rpm. The air density is equal at this rpm, but the Volumetric Efficiency for this RPM will have to be recalulated. The lower the RPM the higher the VE will be, so we will just have an example of .95VE or 95% efficiency.

CFM = 136 / 3456 * 3500 * 0.95 = 130.8 CFM

That's in N/A terms. Now adding Boost, we get:

130.8 CFM * 1.79 = 234.1 CFM or 17lbs/min.

So now match 2.02 Pressure ratio on the Y Axis, and 17lbs/min on the X axis and you have the beginning of boost. with a pull right through the efficiency range of this turbo, or in other words, a great usable powerband, a fun car, and the perfect turbo. So if you happen to have a 2.2 or 2.3 Litre engine, a T04E 40 trim might be the best way to go for you. Please plug in your own numbers and find the proper turbo for your car
 

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dave brode

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Pictures  of a 231 buick carb'd drawthrough setup from an e-bay auction shown are shown in the next post [Thanks Maddog].

This might help guys realize what is meant by drawthrough. This setup takes air AND fuel into the compressor, as opposed to a carb'd "blowthrough" deal where only air enters the compressor, and is then blown through the carb, which sits on the intake in the normal location]. the .

Btw, the 80/81 Transam with 301" V-8 had a similar setup, although the turbos are "larger".

Dave
 
 

dave brode

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Shiftless and All,

This is really a sticky for posting info for those interested in turbocharging. It might be better if we keep it to info and build pics/info only.

shiftless, if it's not a pia, and you prefer, you could delete or move post #16 on

Dave
p.s. - it would be nice to have pics and info on Sean's first combo on his black coupe here [hint]
 

dave brode

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Chevalade said:
Did you think of making your manifolds have a J into the collector instead of a T? Might give you a bit more velocity, and less backpressure.

Ryan
Ryan,

You mean slope the primaries into the log section? Imo, it's not worth much. I did use a 90* on the rearmost primary.
If I was doing something max effort, I'd go 4 into 1 design, but most experts say a pound of boost will make up for any power that might be lost from a decent log design vs a nicer 4 into 1.

Dave
 

Chevalade™

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dave brode said:
Ryan,

You mean slope the primaries into the log section? Imo, it's not worth much. I did use a 90* on the rearmost primary.
If I was doing something max effort, I'd go 4 into 1 design, but most experts say a pound of boost will make up for any power that might be lost from a decent log design vs a nicer 4 into 1.

Dave
Yeah, that is what I was thinking about, but then I remembered that you are not going to be maxing your turbo's out. But the concept would make your turbos more effecient, with less possibility of backpressure.

Ryan
 

dave brode

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Chevalade said:
Yeah, that is what I was thinking about, but then I remembered that you are not going to be maxing your turbo's out. But the concept would make your turbos more effecient, with less possibility of backpressure.

Ryan
It might help a tad. However, I guess that I'm getting greedy. I don't think that the little TB0305s would be hatefully hot at 300, or even 325 each, but the 'jays will be happier, even at 350 each. :devil:

Dave
 
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