I agree, KaijuSenso, something doesn't look right. Because there are 1728 cubic inches, not 3456, in one cubic foot, it seems that to use 3456 in the denominator on the right-hand side of the equation, one presumably would have to alter the left-hand side of the equation to read "50%" instead of "100%," as in:

50% 100% VE Airflow = (Displacement X RPM) / 3456

I need to look at my notes, I may have missed a step and screwed up by putting a doubled number in there. I was fighting a few house guests and a wild 2 year old grandson while dealing with that.

quote Originally posted by timgray: I need to look at my notes, I may have missed a step and screwed up by putting a doubled number in there. I was fighting a few house guests and a wild 2 year old grandson while dealing with that.

While it's probably quite appropriate to saddle "a wild 2-year-old grandson" with the blame for almost everything, this appears to be a legitimate exception.

I think I've found the reason for the apparent discrepancy discussed in the preceding 3 posts.

There is, of course, no altering the fact that there are (12 X 12 X 12 =) 1728 cubic inches in one cubic foot.

However...

...The formula you cite, which has 3456 in its denominator, is the one for 4-stroke engines.

...The formula with exactly half that, 1728, in its denominator, which KaijuSenso cites, is the one for 2-stroke engines.

GM's 60-degree pushrod V6 engine is a 4-stroke engine.

Thus, the correct denominator is 3456, so please feel free to calculate away, timgray!

oh i made a mistake as well when making my argument it seems the formula in the book is actually

Airflow rate = (cubic inch displacement x rpm x 0.5 x volumetric efficiency)/1728

so that 0.5 is the same as dividing by 3456 correct?

quote Originally posted by KaijuSenso: oh i made a mistake as well when making my argument it seems the formula in the book is actually Airflow rate = (cubic inch displacement x rpm x 0.5 x volumetric efficiency)/1728 so that 0.5 is the same as dividing by 3456 correct?

Yes.

Here is a link provided by project34 (thanks again). 4 turbo calculators.

http://www.turbofast.com.au/javacalc.html

quote Originally posted by Hudini: Here is a link provided by project34 (thanks again). 4 turbo calculators. http://www.turbofast.com.au/javacalc.html

You're welcome, Hudini.

I'm hoping that link will prove useful to all those interested in pursuing the idea of a turbo, and in particular, to timgray, who originated the present thread, "Turbos for dummies."

Earlier on the present thread, timgray had been manually toiling away on various turbo-oriented computations, and had shared his computational efforts for the benefit of the rest of us. With these turbo-oriented calculators I'd stumbled across, I'm hoping to return the favor, such that at least some of those turbo-oriented computations will be made much easier with the turbo-oriented calculators I've described in that link.

I finally got my head back in the data and math and yes I verified what has been verified above. It is correct. I am simplifying a calculation. If It needs more in depth discussion I can do that.

I'll be back into this very soon. I just got a second job and that is eating time for projects, but I will have downtime in the hotel room to dig into turbo math again. (Second job is 220 miles away and they pay for hotel stays overnight) I still need a source for some more Turbo compressor maps.

quote Originally posted by timgray: I still need a source for some more Turbo compressor maps.

In regard to your inquiry, timgray, I've located a couple of sources. For example, here is one:
===> http://www.turbofast.com.au/flowmaps.html

Also, did you see this custom "TurboMap" software earlier, and the maps it can create?
===> http://www.turbofast.com.au/turbomap.html

If so, and you're looking for even more compressor maps, then I figure you must really be into this stuff!

actually yes I am really inot turbos right now. There are a ton of different products out there that really give you options. I personally am looking for the perfect low boost turbo for the 3.4 and the T3 is not it. the T3/T4 is also not it. I actually need a T3/T3.5 with a super 60 trim on the compressor and I need some changes on the turbine. Problem is that means horribly expensive turbo as it's completely custom..

I need to figure out if I can modify a t3 to suit my needs. I really need to bring the 75% island down in pressure, and a bigger turbine would do it.

ok, which turbo do i get for my stock 3.4 pr? i keep reading t4 with .63 and 50 trim???

I answered in the other post as well, I suggest a t3/t4 hybrid with a .50 trim but that is for what I am shooting for. it will not be for what you are shooting for. the 3.4 moves a LOT more air than the 2.8 so the T3 from the Tbird will spool up way faster on a 3.4 than it does on a 2.8. this can be good and bad. What boost are you going to run? what rpm do you want boost to kick in at? what changes have you made to the engine?

I used the T3 from the '84 T-Bird with my 3.4L. Still working with Darth to get the tune correct. It does spool very quick and actually hit about 10psi when I was expecting about 5psi. I haven't been able to rev it past about 3k though due to the tuning issues (goes too rich).

Personally, I would like to go T3/T4 next with an intercooler, then one day go with the T4 with a properly built engine.

As Tim said, what are your goals and what have you done to the engine?

quote Originally posted by timgray: I answered in the other post as well, I suggest a t3/t4 hybrid with a .50 trim but that is for what I am shooting for. it will not be for what you are shooting for. the 3.4 moves a LOT more air than the 2.8 so the T3 from the Tbird will spool up way faster on a 3.4 than it does on a 2.8. this can be good and bad. What boost are you going to run? what rpm do you want boost to kick in at? what changes have you made to the engine?

i want to run at least 7 psi, and probably want the turbo to kick in about 3000rpm. and spool up to 5k (dont want to out rev it)
I haven't done any changes, is got about 10k-12k miles on a crate 3.4 motor, ported logs, underdrive pulley, DM ported TB, other than the usual crx intake and free flow cat/flowmaster muffl.
its' a 88 with auto, will that be a problem?

[This message has been edited by 88White3.4GT (edited 11-05-2007).]

The T4 will produce more boost than a stock engine with no intercooler can take. I'm thinking with a boost controller and proper tuning on premium fuel you could run 7-8psi all the way to redline. My T3 is definitely too small for absolute performance but I'm looking for a little kick in the pants, not all out killer power. Look at (IIRC) jeffndebrus's car with a T4. He can hit 18psi.......

[This message has been edited by Hudini (edited 11-05-2007).]

so i think i'll go with a t3/t4 hybrid, because i've read the t3 is too small ( i dont want to create a lot of heat), and the T4 is too large, i dont want to blow the motor up.
I just want to run consistant 7psi safely, the easiest cheap setup that'll be taken out every 2 years for smog (im in CA)...

so on the T3/T4 hybrid, what trim, extruder, inducer size?

Eventually down the road when i have this all set up, i'll do the usual P&P, trueleo intake, and just smooth everything out.

Again, is it a concern that i have an AUTO in the car?

bump

I believe an automatic tranny shouldn't be any problem with a turbo. I would vastly prefer a manual because you have more control over your boost and engine speed. But an auto will work fine.

Seems like you wouldn't be blowing off as much boost with an auto, at least on acceleration, as the Throttle Plate would remain open through the shifting of all the gears... am I wrong to assume as such?

------------------
1984 Fiero SE, White, first love, sold...
1986 Fiero SE 2M6, gold
1988 Fiero 2M4, the Fox
1987 Fiero GT, Blue, 3.4/4T40
Still looking for that perfect CJB 88 GT...

Fierodeletre is correct. With the auto trans you loose less and / or retain more boost than with a manual transmission. Many swear that a comparable automatic turbo vs. a manual turbo, will always have the automatic ahead in a 0-60 race. It makes sense, but I don't know for sure.

Just another small point to keep the post alive. - To avoid any vacuum line problems, I replaced all of mine with Rodney's stainless steel lines. Whether you do this or not, it might be a good idea to use a small wire tie around the end of every vacuum line end you can get your hands on. Even the stainless lines are connected on the ends by rubber connectors so the wire tie idea is still appropriate.

I have read most of the books referred to in this topic, but I must admit, that if you were to print out this entire thread from beginning to end, you would not need to read any of the books. You guys are truly outstanding. Ed

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[This message has been edited by Firefighter (edited 11-06-2007).]

Oh no! there is still a HUGE amount of information in the books that I have yet to cover. Just horribly busy and hoping I get some time to crack open the books and restart the thread here. There is a lot more info still to cover.. Intercoolers are another topic that really needs more details. I also am trying to get some info on aftermarket interceptor type Knock spark controllers that can be dropped in easily to make turboing a car really easy. It can be thrown together with a 85 ecm and some parts, but I think more people would rather buy product XYZ and install it to add knock retard in an afternoon added to an 86-88 Gt.

I also do want to cover ECM tuning and what needs to be looked at.

Tim - Sorry - By saying you guys are outstanding I did not mean to stop the flow of information. It was like an intermission. OK; intermission over. I have a water/ alcohol injection system and not the restrictive boost reducing pipe and radiator intercooler. So take some shots at what you think of that versus the traditional intercooler. With this set up, if you are producing 7 lbs. of boost, that's what the engine gets, you don't loose 2 lbs. of boost from turbo to intake.

quote Originally posted by timgray: ...hoping I get some time to crack open the books and restart the thread here. There is a lot more info still to cover.. Intercoolers...Knock spark controllers that can be dropped in easily to make turboing a car really easy....I also do want to cover ECM tuning and what needs to be looked at.

Those are all interesting topics to me, but I'm getting the sense that properly setting up the ECM of any turbo set-up can be a major challenge. This is based on reading about the experiences posted on PFF by others working on a turbo project, as well as certain comments from Robert Wagoner in his book, High Performance Fieros, when he describes some of his efforts to reprogram the Fiero ECM for his pushrod 3.4L turbo project:

The procedure to adjust this is to:
1) Drive the car and collect data. This takes about 10 minutes.
2) Go home, analyze the data, and reprogram the ECM. This takes about 2 hours.
3) Go back to step 1 about 40 times. This takes months!

While I appreciate that author's candor, his comments don't exactly inspire the notion of an easy turbo install, do they? That is why I applaud your interest in tackling the ECM tuning issue.

Any updates timgray? I miss the turbo discussion

Me too. I was all set with my T3 setup and 7730 ECM on a 3.4L OHV engine with knock sensor built in but could not get the car running right. (I must be a PITA to Darth Fiero) Well today I verified a wiped cam lobe. No wonder we could not get it to run right.

So anyone want to suggest a good turbo cam? Should keep us occupied til timgray picks up on his research. Rumor is the CompCams 260H is an acceptable turbo cam. It is not perfect but more turbo friendly than the Crane H-260-2 or H-272-2. Something about zero overlap being the best for a turbo. Anyone?

Ideas on intercooler...

I have see a lot of neat air/water intercoolers out there and honestly those would be the best solution for the fiero as the cooling radiator can be placed elsewhere like up front or elsewhere. Disadvantage is complexity, adding a pump and plumbing.

Does anyone know of some smaller air water intercoolers out there that are on stock cars so we can go find some parts in junkyards to keep the cost on the cheap?

EDIT: I havent forgot, Other things have got in the way of the car and car stuff. I will be back on top of this very soon.

[This message has been edited by timgray (edited 02-20-2008).]

the GMC syclone and typhoon had an air to water intercooler

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87 Fiero GT 5sp with Vortec L35 4300 Turbocharged V6
Bully Stage 2 clutch
Syclone intake manifold and engine management with Moates adapter and chip burner
Air/water intercooler and Devil's Own progressive water/alky injection
50lb injectors, 3 bar map sensor, Walboro fuel pump and Jabasco Intercooler pump
LM1 wideband on custom manifolds and 3" stainless exhaust system
T31/T04B S4 turbo with a Super T61 in the box
S10 caliper conversion.
Murphy's Constant Matter will be damaged in direct proportion to its value
Murphy's Law of Thermodynamics Things get worse under pressure.
Arthur C. Clarke "Any significantly advanced technology is indistinguishable from magic"

I just found a new potential supplier of goodies.

http://www.milzymotorsports.com/

They have all sorts of stuff for all 2.8, 3.1, 3.4, 3.8 and 3.9

There business is mainly Z34 and grand ams but it looks like a good quality shop.

--------------
I just picked up a Saab Blackstones intercooler - 50 bucks.

That looks cool

Where ya going to mount it?

I believe it will fit in the wheel well on the drivers side. I have my cold air intake coming from that area now. The space is pretty large and with Stage II scoops the intercooler should be beneficial for any turbo. I've heard a lot of people have used these 1 way or another. I've also seen just below and above the engine grill but there is a lot of hot air that comes out of there. If I relocate the battery to the front trunk area then the other side scoop can hit an oil cooler.

Those things suck up like 4psi, and only support ~ 180hp. They are garbage, trust me.

Anything is better than hot charged air... We'll see how it works and if not... I've seen custom fabricators for intercoolers too. I'll have one made that "is" the wheel well. Wouldn't that be cool. All snug fit and get the most out of it. I'm sure it's pricey though

Anything for my garage wife!

Little change for something that may work. better than several hundred and wondering if it will when it's all said and done. Ebay is good for that sort of thing.

[This message has been edited by unboundmo (edited 02-28-2008).]

Ok, I actually have time to pick this back up. We have covered almost ever basic about choosing the right turbo for your engine, we also covered installing it and getting it all hooked up. Many setus will be modified to LOWER the compression on the engine. Lower compression = safer boosting. Also many will rework the heads a bit and carefully polish the heads combustion chamber to make sure there are no sharp ignition sites to cause detonation as well. These were VERY important in the past as you did not have an ECM to control timing, there was a mechanical boost controller that actually moved the distributor to adjust timing at the extremes. But if you can open up your engine to make some upgrades, these will help you. Polishing the heads will help even in the low boost situation we are building here. But it's not required. Once we get our turbo installed the next step is to make sure we have enough fuel. running with the standard injectors and turboing can get you in big trouble as the engine can lean out and cause failures.

Two ways of doing this are either increasing fuel pressure when you have a boost in progress and using larger injectors with ECM pprogramming to do the job. OR you can do things the way the Nitrous guys do and use a fuel enrichment system. A second fuel delivery injector that acts a LOT like a wet No2 system. Because we have the ability to reprogram the ECM I am going to focus on the more stock way of larger injectors and fuel pressure. We are going for the tiny 6psi so more fuel pressure could do the job alone, but can be finicky. I'm going to only use larger injectors. Going one step larger, or using the injectors that the 3.4 uses in the 2.8 would be a good setup up for a low boost like this. A good set of stock 2.8 injectors could handle our low boost situation but why risk it, we have to reprogram the ECM anyways.

Fuel injectors. This one can get "sticky" it's a hotly debated topic and I'm not going to touch it. If you want to SAFELY boost then run rich. you can calculate for your turbo by using the following site... http://www.witchhunter.com/injectorcalc1.php4

3.4L 19lb per hour injectors would be a ssomewhat good match for our low boost project here. a 3.4 should use 23 pound injectors. These are wild generalizations, you can calculate exactly what you need and I can dig up and post a big paragraph on how to do those calculations here if we want to go digging into that.

After some discussion on fuel and injectors. I'll start on the timing issues.

Some very good information here: http://www.grapeaperacing.c...ch/turbochargers.pdf
and at Max-Boost here: http://www.max-boost.co.uk/.../exhaust/exhaust.htm

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3.4L S/C 87 GT www.fierosound.com
2002/2003/2004 World of Wheels Winner &
Multiple IASCA Stereo Award Winner

Welcome back, timgray!

This is in regard to the fuel injector size calculator you've located:

quote Originally posted by timgray: http://www.witchhunter.com/injectorcalc1.php4

The implications of that fuel injector size calculator you've located seem interesting. For example, it appears from that calculator that what its developer was focusing on to estimate the injector size needed was not necessarily the amount of boost the engine uses, but a consequence of that boost, namely, the amount of horsepower expected from that boost.

I see that calculator also assumes a greater BSFC figure if the engine is turbocharged, and a lesser BSFC if it is not. Does that in turn imply that turbocharging cannot be considered an economy measure? (I'm not trying to start an argument with anyone here, but just trying to better understand the implications of the math underlying this calculator you've located.)

Also, with that fuel injector size calculator, the numerically higher BSFC assumed for turbocharging (0.60 to 0.65) versus supercharging (0.55 to 0.60) or normally aspirated engines (0.45 to 0.50) seems to imply that turbocharging is the least fuel-efficient of those three set-ups, given that of the three, it has the highest BSFC ("the amount of fuel consumed in pounds per hour for each horsepower made," to use the terminology of the calculator's developers in explaining BFSC). I don't even know why I say this, but the notion of turbocharging being the least fuel-efficient approach just seems counterintuitive to me. Am I overlooking something in the math, or is turbocharging in fact less fuel-efficient per horsepower created than supercharging an engine or leaving it normally aspirated?

It's making assumptions to make things "safer" in boost. in real life you would do some more tuning to get things better. with fuel injectors you never EVER want to be running at 100% 80% Duty cycle is the max you want to run at for safety, and their calculator seems to be making that assumption. Unless you go insane large on your injectors you can tune things in better with the ECM tuning. If you were turboing a Carbed engine then the .6 factor would give you even more safety under boost.

and yes, I have yet to see a turbo car that has decent fuel economy.

I hope you mean a turbo Fiero with decent fuel economy. Lol, hard to keep ones foot out of it when it's so much fun.

I do have a Volvo S40 with a 1.9L turbo and it gets 34mpg highway. That's 75mph, 4 people, in the summer with A/C on. I have driven this car from Tennessee to Florida several times and it rocks. The 160mph speedo may be a bit optimistic.

I've been looking at the STS turbo systems design. The remote mount would seem to help with a couple potential problems with turbos. Bearing failures due to heat soaking and the -little bit- of intercooling in that, the output of the turbo is away from the heat of the engine. Lag seems to not be a problem according to the web site and reports. Another positive factor is that the turbo replaces the muffler and makes installation to appear much easier. With the compact design of our Fieros engine package I feel that this could be a winner. What are your thoughts? is there anything I haven't considered?

How does it handle oil return to the engine? wftb (IIRC) has an ecotec with a low mounted turbo and he had to install an oil pump to push the oil uphill back to the engine. Otherwise his turbo smoked like crazy.

Mine is mounted high, about equal with the upper plenum. I just finished it yesterday and it runs like a banshee. No oil return problems either. I don't know about longevity yet, of course.

The STS kit includes an electric oil pump. With a little creative wireing (If not already thought of) this could be used as a turbo timer.