Inliners International Forums General Discussion Hi Performance Turbo setup

I know turbos have been discussed to death here, but I had a few more questions. I've constantly got turbos on the brain, esp. for my 250. I know how the 2 types of systems work (blow through and draw through), but I don't know how the actual systems are run. I know a blow through system would be better, but how does the draw through system actually connect to the manifold, etc.? Turbos seem like the best bang for the buck, when it comes to street vehicles. Also, if anyone had any thoughts as to which brand of turbo is a good fit for inlines. Any info would be great. Thanks. John.

Hi John, you know the turbo bug is not a bug, it's one of those diseases that you never get over, especially after you've ridden or driven one that pushes 25 or 30 psi of boost...

The difference between systems is where the fuel gets put into the air stream. A blow -through does just that - it blows through a carburetor and puts it, as well as everything after it, under pressure. That is #1 = turbo, #2 = carb, #3 = manifold and engine. A suck-through places the carburetor in front of the turbo, as in #1 = carb, #2 = turbo, #3 = manifold and engine. Either system can use an intercooler after the turbo, but a suck-through will have major problems, so it's rare for one to be used.

As far as brands/models are concerned, that's not really a big consideration. You have to get one that is sized properly for the engine displacement, the power you want to make, the rpm operating range you want to use, and the engine characteristics. About the only real commonality you should look for is bearings on the shaft, not bushings, and a water cooled center housing. All center housings have a pressurized oil line to them and a gravity drain line, but not all are water cooled. If somebody tries to talk you into less than that, and you want to race it, you're asking for more expense down the road.

Ak Miller wrote a great book some years back, I don't know if HP Books still has it in print. He used a 230 and customized his exhaust manifold to bolt the turbo onto the top of the motor. A single Corvair side-draft carb on a suck-though system made about 275 horsepower (if I remember correctly) on an otherwise stock motor. I think he also used water injection to cool it down a little.

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David
newbie #4153

Thanks for the info. I really wanted to know how the draw through type is physically set up. I.E. do I have to buy a special intake manifold, or do I need adaptors to use one on an Offy manifold. I was just curious because I had seen photos in Leo's book, but it didn't really say how it was physically connected. It seemed like there was some type of adpator on the side of the intake manifold for the draw through system to mount the turbo. I didn't see how it was all connnected. Thanks for your help. John.

I dont mean to take over the post but i have a question about turbo setups.
What should the setup be for a blow-through system. Can you use headers? Would it be to place the turbo at the end of the headers, then the intercooler and connect that to the air filter element or directly to the carb? Im confused where it should hook up to and how? if directly to the carb or how? Also would 10:1 or 9:1 compression ration be too high and would water injection help?

1. a custom header is generally used, and the pipes are as short as possible to keep the turbo as close to the head as can be. Turbos depend on taking heat out of the exhaust stream and converting it to inertial energy. If you put the turbo too far away and the pipes cool the exhaust first, then you've lost energy before you can extract it.

2. the intake air for the turbo comes from the air filter, gets compressed in the housing, goes into and out of the intercooler, then gets piped to the carb. A bolt-over housing is used to seal the pressurized air into and through the carb.

3. generally, 8:1 compression is about the highest normally used for a turbocharged engine. You can go higher, but the cost and technology increase exponentially. You need to remember that pressurizing air on the outside of the motor gets the same results as just increasing the compression alone. An example would be if you pressurized an engine intake to 1 atmosphere (about 14 psi boost), that would be the same as stuffing twice the regular amount of air and fuel into the cylinder. If the turbo engine is 8:1, then the equivalent aspirated ratio is 16:1. That's a big increase. That's why the general rule of thumb for turbochargers on STOCK engines is a doubling of flywheel horsepower for each atmosphere of boost. There's some other info that I'm leaving out, of course, dealing with head flow rates, cam profiles, intake and exhaust considerations, etc. that can substantially increase those numbers.

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David
newbie #4153

I would like to discuss this setup more because i'm really interested in one. What would be the best turbo for a 250 taking into consideration all the other things you mentioned and the best intake to handle the amount of boost from the turbo? Would the stock exhaust manifold do the job or are shorty headers needed or some sort of custom made manifold?

Im thinking on getting a turbo not to race the car, but sort of like volvos use a turbo. You are not going to race a Volvo, but still you know the power is there if you need it. For better overall performance, so i´m not looking for a really big turbo or anything like that.

[This message has been edited by tatao (edited 09-18-2003).]

A turbo might be cheap to start with but all the extra pluming and header work will be a challange for someone with little or no fabrication skills. An option would be a centrilgul blower. If you have the extra room in front of the motor it should be pretty easy. A blow though carb setup from a v8 would almost go right on all you need is a few bracket's and the carb you were going have to buy anyways. This seems to be the best upgrade because most inliners have a aftermarket intake and headers allready.
www.procharger.com

Steven

Mighty6--I just my catalog from Procharger. I agree with you about the centrifugal super being easier to plumb. I've been thinking about a turbo, but since I've learned more about the centrifugal super I like it better. No turbo lag, constant power, intercooler (just like a turbo), less plumbing. I just need to get a book on turbos and supers, and figure out what I would need. I think the super would be an overall easier setup. Just my 2 cents. I'm still torn between the 2 though. I guess I really need the money first. Oh well, it's good to dream. Thanks. John.

I have a stock engine and am ready to spend some money on it to make it a better overall performer. Maybe a list of things needed for the turbo would help so i can look at the cost and see if I go for it. I'll read about the supercharger, maybe i'll change my mind after reading that. I think getting a used turbo is easier than a supercharger though. So what is needed for a turbo, everything from carb, intake to exhaust?

Yes, you will need everything from the air filter to the exhaust pipe. As there were no turbocharged inlines from the factory, all of the plumbing has to be custom. About the only parts you can use without modification are some types of carbs and an intake manifold. You could try to get away with an unmodified exhaust manifold also, but you risk leaks and warpage due to the heat involved.

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David
newbie #4153

I have never run a turbo or a centrifgul blower. I would think a centrifugul blower would lag just like a turbo untill you get the rpm's up maybe not as bad. But that's not all bad because of the low end grunt of the six. I would think you could the cost of a centrifgul blower over a turbo because of a lot of varibles like a header, intake, piping, fuel system, blow off valve, waste gate, MSD boost box.

I looked into a turbo setup and doing all the fabrication myself for a race motor and it was around $3000.00 this is just the turbo setup. I'm going to stick with my nitrous setup for right now. A 100 shot of spray will do wonders to a properly tuned motor.

Steven
www.mighty6.com

There's no space for a supercharger in my caprice. Check out this link i found over at fordsix.com and tell me what you think about what it says. http://www.cse.uconn.edu/~yelevich/turbo/turbo.html
That would be sort of what i am planning or maybe go to a junk yard and see if i can get the whole setup from a diesel engine. I think that would work if i modify the other stuff right?

Read all of what you can find, as education won't hurt anything. And the more questions you have, the more you can get answered by reading.

Diesel turbos and gasoline engines are not compatible. They are just too different in airflow requirements (when and how much in particular).

T3 units for 4-bangers are fine, but remember what I said about matching the turbo to engine size? The little T3's are used on 2.0 to 2.5 liter motors. You have a 4.1 liter 6-banger. It would REQUIRE 2 T3's if you didn't modify them. And 2 turbos will just about double the cost of installation. That also doesn't take into account the fact that the motors they were installed on used port fuel injection. That means you would have to use a blow through system or also use port injection due to the lack of appropriate seals on the turbine shaft. You can't use a suck through system without those seals.

Keep on searching and learning, that's the same thing I've ben doing for 44 years.

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David
newbie #4153

hmmmmmm...interesting, hadn't thought of that "little" fuel delivery difference. I'll read up some more on turbochargers, I'll try to get a book someone mentioned on another post and see what i learn. Do turbochargers increase or decrease gas mileage? I would think it would decrease cause more fuel has to go along with the compressed air. How do you connect the pipe going from the intercooler to the carb? What's the best carb to use a 4bbl, 2bbl, or multiple 1 bbls?

tatao--The pipe running from the intercooler to the carb is hooked up by two ways. One-You can connect the pipe to the top of the carb, but you have to use a specially built carb. Two-You have to use a carb encloser that completely surrounds the carb.

I do not know the answer to the mpg question. From what I've read, mpg is slightly decreased, but it's not by much. The power gain is well worth a couple mpg in my book. I know you can use four barrel carbs. I would think you would be able to use a two barrel carb also, since you're dealing with a single carb. Multiple one barrels would be difficult. I don't see why anyone would want to run multiple one barrels when they are running a turbo. Unless it would be for the quick throttle response that's common with multiple 1bbls.

As far as books go, Leo Santucci's book recommends "Maximum Boost" by Corkey Bell, "Turbochargers" by Hugh MacInnes, and "Super Power" by Larry Schreib.

For supercharging he lists "Super Power" by Larry Schreib (same as above), and "Street Supercharging" by Pat Ganahl. I hope this helps. John.

I picked up a turbo from a Buick Gran National at a swap meet. I think they were 231 cu in. i figured this might be about right for my 261 which has a stock comp. ratio of 7.8. If I understand things right you should get your gearing set up so the turbo isn't producing much boost at normal highway speed so it doesn't kill your mpg and produce heat constantly. I figured if i ever get mine installed I would limit boost to about 7 lbs. It seems to me that port injection might be a whole bunch easier than a carb. Gael

chevyman1937-- You should've picked up the whole engine if you could have, then donated it to me. The Grand National engine with the turbo is a beast. I've heard so many stories about how fast they were, even straight from the factory.

Anyway, I don't know anything about turbo selection, but that you have to match your engine and turbo very well to avoid turbo lag and get the setup you wanted. TO my understanding you want the boost to come in at low RPM, around 2000rpm I think. Here ya go, I just found it in Leo's book....

"What you want, at least for street, is to set the boost to come in at 2000rpm in high gear (not overdrive)."

With port injection you would run into the same setup as a blow-through system on a carb. The only diiference being you would be using a throttle body instead of a carb. Do you have a TPI setup on an engine, or are you just getting me all excited? What heat are you referring to when you say "produce heat constantly"? The turbo is going to heat the air less than a roots type blower. Not to mention you can use an intercooler with a blow-through system. The intercooler will provide you with more power, ability to run higher boost levels, along with better throttle response. I hope this helps. Thanks for all the replies guys, and keep them coming. John.

John, I'm not running a TPI or a turbo now. I'm just kickin around the idea and enjoy the discussion. I'm talking about running a turbo on a street engine. The way I understand it is if you run more than about 8 psi boost for length of time you will creat so high of combustion chamber temp. that you will fry pistons. 30 psi boost is ok for 8 second blasts at the strip but not on a street engine. If you put one on keepus informed on your progress. thanks Gael

chevyman1937--I'm pretty sure you're right. The most I'd run would be around 10-12 psi constantly, but I'd make sure the engine was built for it first. It's going to be a loooong time before I can get a turbo or a centrifugal supercharger. I can't decide which one to go with. Maybe one of each. Some day. Anyway, there's a guy at my school who has a Grand Natiol with the original motor and turbo. Pretty neat stuff. Now only if I can get him to donate it to me. Thanks again guys. John.

Hey John,

Just some more peanuts for you to chew on in your dreams, but Detroit Diesel used a turbo to pressurize the supercharger on several of their 2-stroke engines. Those things were big truck motors, sure, but there are always pictures that I come across of guys that try a similar approach to make huge power, i.e. multiple compressors of whatever type in series (one after the other).

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David
newbie #4153

Which turbo would best suit a 250?
Would a Garrett TO4B turbo get the job done safely and efficiently? Here in El Salvador i can get a TO4B for about $225, but they use it for Mercedes Benz buses. Since they use if for buses that's why I ask if it would suit an inline 250 or would it be too big? Which turbo model should it be in case the the TO4B is not appropriate?
Should it have a ball bearing or a standard bearing?
I believe my car has a heat riser cause the intake manifold seems to be connected someway to the exhaust manifold. I cant get a good look but it seems that way. Would that be a heat riser? If it is how would that affect the turbo setup? If i get the turbo im planning on getting an intake for a 4bbl and a custom made exhaust.

The TO4B comes in several configurations, and may or may not work as a bolt-on. You would need more specific information about the compressor and turbine trims and the housings. There are various sizes available, and need to be matched to the engine requirements. My gut feeling is no, the diesel unit will not work well, as those motors don't operate under the same circumstances as a gas engine. A diesel motor is chosen for a specific job based on it's torque output, and they don't turn nearly as fast as a gas engine to make power. So the air needs of each type are vastly different, even if the displacement, for instance, is the same.

What you might want to do is to visit this site page and read what they have to say about turbo choices. There is lots of info there, as well as other links.
http://www.turboneticsinc.com/guidelines.html

I printed almost all of their turbo maps last year when looking for information on a turbo choice for my 292. Since I still don't have the engine together, there is no reason for me to forge ahead and spend money yet on the periphery. If you need some help on the math that is needed to develop your choice, give a holler and an email, and I'll give you the formulas that I use.

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David
newbie #4153

You guys should get both of Corky Bell's books, one on supercharging and one on turbocharging.
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I have been doing some thinking and have a couple of questions, maybe you guys could help me.
The intake manifold should use some form of heat so the fuel is vaporized as it goes into the combustion chamber. If you dont use an intercooler in a blow-through setup, would the hot compressed air be enough to keep the fuel vaporized? (or would a suck through system be better to keep the fuel vaporized) If that works would it mean you wont need a source of heat for the intake or will you still need one?

Would the stock manifold be too restrictive for the flow of the exhaust gasses to the turbo? I'm thinking of custom making a header for the turbo but if it wont make much of a difference then i dont think it's worth spending the money. I was looking at pics of Dr. Santucci's turbo setup and his exhaust manifold looks pretty much like the stock one. There aren't that many bends or flexes and i dont see a collector either. How neccesary is it to have a collector. If I go for the headers, since im not gonna be revving this car too much,( Im not racing it) I guess short diameter tubes would be the way to go for the turbo headers or the other way around. WHat size pipes 2 or 2.5 inches?(they are goning to be short lenght not to lose much speed) Would a Holley 390 with vaccum secondaries get the job done as far as carburation goes?

Would the water injection setup i mentioned on this site help at all when using the turbo without the intercooler? Or would a better water injection system need to be used?

Please let me know what you think. Thanks.

[This message has been edited by tatao (edited 10-03-2003).]

tatao- In Dr. Santucci's book there is a photo of a draw-through system using a water heat setup to the manifold. I would think if you are going to be driving it on the street you should have some form of heat to the intake. The water heat to the manifold is pretty easy to hook up.

I wouldn't use a stock exhaust manifold for a turbo. The whole point of a turbo is to make power. I would think the stock exhaust manifold would be too restrictive. I believe there is a picture in the "Power Manual" of someone using the stock exhaust manifold. I think it would be an extremely easy setup with that, but it would hurt exhaust flow. Maybe if you had it extrude honed. This is just my thinking, I could be way off base.

The stock intake would be about the same deal as the stock exhaust manifold. Too restrictive, esp. on the intake side. If you had a turbo you would be trying to force all this air through a tiny opening in the intake. A four barrel or bigger two barrel would probably be the best bet. The carb. you get would depend on what type of setup you are going to use for the turbo (draw-through or blow-through). As far as the water injection goes, it would allow you to be able to run higher boost numbers. The blow-through system with an intercooler would be the best system to use. It requires more work than a draw-through type, but to my knowledge it is well worth it.

I don't know about the collector. If you ran split headers you would have to merge them together then run it to the turbo. A custom built exhaust for your application would be the best thing, but not the cheapest. I think that's about all that I can think of right now. I hope this helps some. John.

What do the 2 numbers for the TURBINE HSG represent in the turbonetics tech page? Im told that .69 a/r ratio is the way to go. Looking at the compressor maps I believe the one with the V1 trim would work better. Does it matter if the turbine hsg is .69/.81 or would the .81 be too much?

tatao-- I went to that site before, and it's all Greek to me. I have a couple catalogs, but none of them have a specific setup for any engine (except newer stock engines). This means figuring out eveything on your own, or hopefully with help. I couldn't tell you the first thing about turbine trim or compressor housing numbers. The best thing I would recommend would be to buy the books mentioned before, give them a read, then contact some of the turbo companies for setups. Sorry ,I know this wasn't much help. John.

Could a Quadrajet with 750 cfm be hooked up to a turbo in a draw through setup for a 250 or would it be too much carb?
How hard is it to tune and calibrate a Quadrajet to use it in a 250? Or should I stick with a Holley 390 instead? Which carb would work better? How do you hook up the carb to the turbo, any special adapter needs to be custom made?

tatao-- I would think that the 750cfm would be too much carb for a 250, even if it was running a turbo. You might be able to get it to work alright with a lot of tuning. I think a 390cfm or 450cfm Holley would work best for a mild 250 and turbo. I'm planning on using an Edelbrock 600cfm electric choke on my 250, but only because I have it on hand. I'm going to buy a kit for the carb and try to tune it so I don't have to worry about over carbing the engine. I've heard good and bad things about the Quadrajets. I've only heard the results from them being used on V-8s. They are good because of the small primaries which give good throttle response, but the secondaries are really big, esp. for use on a small 250. I think the smallest cfm for Quadrajets was 725 or 750 cfm. As far as tuning them, I have heard they work great for larger engines, but that most people don't know how to tune them. Again, this is what I have heard from various people. I have almost no experience with the Quadrajets.

As far as how the carb is run in a draw-through setup, I'll have to break out ome of my books. I can tell you how the system should work, but I can't remember right now how they are physically connected. I posted that same question somewhere on the board (maybe this thread), and I think David helped me figure it out. Not sure right now. A blow-through system is easier to understand, because everything is where it usually is. I hope this makes sense, my brain is kinda fried after school today. John.

The draw-thru buick setup from '78 to '83 used the 750cfm Q-jet. They pined the secondaries to limit there opening. One of the modifications for this setup is to remove the pin.

Would the setup from a buick like the one mentioned above work for a 250? I believe those were used for 3.8 liter engines. I've seen one on ebay which includes the turbo and the Quadrajet carb going for about 50 dollars. How well would that turbo setup work being that it was designed for a 3.8 liter engine and would be used on a 250? What would the maximum boost for that turbo be?

I think it would be much cheaper to buy that setup and just adapt it to the 250, with the custom pluming of course, but if that setup wont work well with the chevy 250 then i would rather get a newer turbo designed for the engine's capability. So what do you guys think?

kesteb-- Are you talking about the 3.8L V-6? I'm assuming you are. I don't know much on those engines other than they were really quick.

tatao-- I wouldn't be able to give any info on that turbo. There is a guy at my school who has a Grand National with the 3.8L turbo. From what I've heard it really screams. The best thing to do is research. If you're interested in using the 3.8L turbo, then you need to find out any and all info on thst turbo. Then compare those results with what your goals are (along with your engine specs). I would be careful about picking up second-hand turbos. I'm sure there are alot of good ones out there, but you can only go by what someone tells you about it. The first thing to do would be to read as much about turbos as you can, find out what turbo you would work best, then you can compare those specs to factory turbo specs and see if you come across a match. Turbo selection is key. I hope this helps some. John.

Awesome update. One of my instructors here at school (NTI) just got a turbo for his 232 Jeep straight six. He said it a stroker motor (I can't remember the original cubic inches), with Clifford intake, different cam, etc. He said he got the turbo from a Subaru with a flat six. He going to try it and see if it'll work. He plans on using the stock exhaust manifold, but he's going to see how everything will set up with the different systems before he chooses which setup to run. (i.e draw-through or blow-through)

Also, I just ordered some books (Maximum Boost, and Turbochargers) from motorbooks.com I'm planning on that and seeing what I can work out. From talking with my teacher, and thinking about it, the stock exhaust maifold might be the easiest way to setup a turbo on a street vehicle. Depending on what I decide to do, I'll probably go back to the stock exhaust manifold, but have it extrude honed. Very fun stuff. I'll keep y'all posted on what my instructor finds out. Thanks. John.

Yes that is for the buick V6. It should work OK on your 250. Some fabrication required. I have considered using one on my \6.

A good place for information is http://www.turbobuick.com and http://www.turbobuicks.com . Read the "Before Black" section.

Does somebody make a two BBl carb adapter to fit onto the stock manifold?

Maybe something like this?

http://cliffordperformance.net/Merchant2...tegory_Code=C21

or maybe this? good source for a carb too.

http://www.stoveboltengineco.com/acartpro/product.asp?productid=91

Joe

Thanks Greg. Yeah I saw it on clifford's site after I had posted. Thanks. Anybody know how difficult it is to rebuild a carb to see boost. Never even had a carb apart, so its all greek to me. Or is there certain carbs that I can just bolt on, or a place that sell's two barrell carbs "already" hopped up?