turbo off a diesel on a gas v8 what happens?

ok so I don't know poop on setting up turbo's I have a roto-master turbo off a banks 6.2 conversion. ar .6 and 1.0 are those ratios I know nothing about that are stamped on the housings.. so. will I get any performance gain if I run this turbo on a 305? whats gonna happen?

 

I am not a turbo expert by any means, but a while ago I came across a small diesel turbo that I wanted to use on a gas inline 4. After talking to a few 'turbo' guys, they said it wasn't a good idea because the diesel turbo is set up to make boost and operate at fairly low engine RPMs (<3000), while the gas turbo is generally set up to operate well out of that range. I seem to remember that it would wear the diesel turbo out fairly quickly. Just what I have found out with the minimal amount of research I did.

 

so anyone else?

 

I'm not a turbo expert, but a turbo, unlike a supercharger does not see what RPM that the engine is running. The turbo is powered by the exhaust gas coming from the engine. A turbo is a turbo. As long as you don't create too much boost you should be OK. Good luck and let us know how it works.

 

Ok, I come from a Dodge Cummins background and have replaced the turbo on my play rig several times in search of more power so here goes,

On a diesel the turbo is spooled by heat rather then rpms, hence why you will see header tape on manifolds/tubing in twin setups and big single charger setups.
On a gas motor the turbo is spooled via exhaust flow, rpms, that being said the guys with hopped up ricer hondas love the stock hx35 that come stock on the second generation dodge cummins trucks, the reason that they can spool a turbo meant for an engine twice or more their size is because they can rev real high.

If your turbo has a 1.0AR exhaust housing it will be quite laggy but if it has a .6AR it could very well spool good in your application, I could use more info on the specs of the turbo, i.e. measurements. I run a 64/65/12 on my cummins and it spools quick, I am guessing that early turbo is in the range of 57/60/11 roughly and it would flow well on that 305.
What kind of rpm do you plan to use, what is the intended purpose of the build?

 

http://www.wcengineering.com/articles/dieselturbo.html

google is your friend.

 

Diesel turbos generally aren't sealed for running in intake vacuum, so you'll want to set it up as a blow-through rather than draw-through arrangement.

 

Listen to a semi tractor while going through the gears. The turbo does make boost when the truck is accelerating in lower gears, but not as much as when in higher gears because the engine develps more exhaust heat with higher load, thus the turbo spins faster, develops more boost, you can hear more.
A supercharger is a fixed volume air compressor. Change output by playing with pulley ratios.

 

I think it's spooled by the volume of exhaust gases. Which are much higher at low rpm on a diesel than on a gas engine.

 

I'm not a expert either but have ran Turbos on my Diesel Landcruisers. Rule of thumb, if you are going to pick up a used turbo, pick a turbo off a similar sized engine. You don't want to use a turbo from a small import car on a V8, and you also don't want to use a turbo from a Duramax, Powerstroke, etc. The Banks turbo is bigger than what came on a 6.2 from the factory, probably not the best choice. I would talk to the professionals and select a new turbo sized for your application, spend the extra money you'll be glad you did you'll get the performance you are after


http://www.turboneticsinc.com/sites/default/files/HowToChooseATurbo.pdf

 

cheap hp.. more so tourque. its for a 5200lb bread truck that is being converted into a motor home.. the 60 is on the intake side and the 100 is on the exhaust.. this thing is slated to have 4:11-4:56 gears and a top speed of about 65 with the motor buzzin. I'm not looking to have a 1000hp race car.. just want to bump up the performance a bit so i can get up to freeway speed a bit faster then 5 minutes... and I have the turbo, and can make an adapter to bolt on to the stock exhaust manifold.

 

I'm no expert but I have actual experience with a hillbilly turbo system.My son in law runs them off shore type power boats.He had a turbo off a JD farm tractor he rigged up to a 454 Chevy engine.No science just a suck through system made of welded tubing and quessed at the jetting on the carb.I helped him a bit on the project,it ran well,quite powerful.No boost control,ya keep boost within reasonable limits by playing with the throttle like pilots did in some WW2 combat planes.The Turbo got a leaky seal,lots of smoke,Was difficult to control detonation....He switched over to a GMC type supercharger.
Didn't Ak Miller say "if a turbo you have tried,then pistons you have fired" ?

 

hmm reading that page.. looked on google for ar map explanations and found a bunch of mumbo jumbo I didn't understand.. that page didn't come up thanks zman

 

This is Zmans link..

Diesel vs. Gasoline Turbo Design
There is much confusion about turbos and their use on diesel engines compared to their use on gasoline engines. We'll see if we can shed some light on the subject.
The principals of their operation are the same and their plumbing of intake air and exhaust gases are the same, but where the real issues come into play are the combustion pressures and temperatures, operating RPM range, and the driving cycle.
Diesel Engines and Turbos
Let's start with the basics. Whether it is a semi truck or a generator set, turbocharged diesel engines are typically large displacement, low operating RPM power plants. They run in a very narrow RPM range. Diesel fuel is atomized as it enters the combustion chamber and upon compression (with only residual heat) the air/fuel mixture lights off. The combustion pressures are very high due to the high compression ratios needed to ignite the mixture. Because of the high compression pressures, mechanical parts must be strengthened to handle such loads: connecting rods are larger, crankshafts are stronger, and pistons are bigger. All of this reinforcement means that there is a much heavier rotating mass, which is more difficult to spin at high RPMs, so diesel engines tend to be low RPM power plants.
As with any internal combustion engine, the more air and fuel that can enter the combustion chamber, the more power it will produce. Diesel engines, because they are spinning at low RPMs, can't really "suck" in enough air to fill the chamber on each cycle, so the addition of a turbocharger helps.
Diesel burns at low temperatures and exhaust temps are typically in the range of 500-800ºF and the volume of exhaust gases is quite high. When sizing a turbo for a diesel engine, the turbine section must have enough flow for the high volume of exhaust gas and minimize back pressure. It also must flow a very large volume of intake air in order to keep the cylinders filled. As mentioned previously, diesel engines already run high compression, so adding a turbo is to increase the volume of air entering. The boost is typically very low: in the 5-8 psi range. (I know there is someone reading this saying "Hey, I've seen tractors that are running 40 psi of boost." You may want to look into that because it is not uncommon to have people mistake "inches of manifold pressure" for "psi of boost." There are a few show trucks and tractors that run outrageous amounts of boost, but remember we are dealing with the drivable vehicles here.)
Now that we have this turbocharged diesel engine with a huge turbo to make the volumes that we need, let's talk about spool-up times and drivability. Spool-up time? Any watch with a second hand can time the spool-up of a diesel turbo. They aren't the fastest in the world, but they don't have to be. Most diesel engines are designed for continuous reliable running, not 0-60 sprints. And even though that huge turbo takes a while to spool up, it also takes a while to spool down. Most diesel engines don't have throttle bodies (they use metered fuel to control engine speed), so there is less back pressure when you lift of the accelerator, and therefore less to spool the turbo down. The only spool down is from the reduced exhaust gases. These larger turbos spin at lower RPMs, typically below 50,000. So, you can size the turbo larger to get the volume you need without the main concerns being spool-up time.
Gasoline Engines and Turbos
Gasoline is much more volatile than diesel fuel: it burns hotter, ignites quicker, does not need to be atomized for combustion, and also uses a lower air-to-fuel ratio than diesel fuel. These are smaller displacement engines that need to operate at a wide RPM range for drivability. They already have four valves in the head so they can get a lot of air and fuel into the cylinder and exhaust gas out. So we have an engine that runs very well, but we want more power, so we (or the manufacturers) add a turbo.
Our engine already "breathes" fairly well due to its head design. There are some four-valve heads that achieve 98% efficiency at filling the chambers. What we need to do to get more air in is to pressurize it, so we need more intake air pressure along with the correct volume. If we were to run 5 psi of boost, that would be just enough so that the engine doesn't waste energy "sucking" air in. If we really want to make more power, we have to step up to the 10-15 psi pressure range, along with the correct volume. So, we need high pressure and volume. In order to generate these higher boost pressures, the turbo spins at a much higher rate, from 40,000 all the way up to 125,000 RPM.
We need to have quick spool-up time of the turbo. We tend to wind through gears more than a diesel, so there is more up-down-up in the RPM range. Unlike a diesel, we have throttle plates that close off the intake tract, so whenever the throttle closes, the turbo spools down due to the back pressure and lack of exhaust gases. The closing of the throttle plates can cause a significant surge in the intake tract and can even damage the compressor wheel if it is severe enough. With our broad RPM range we need to make the proper volume of air for the engine speed. Our engine needs twice the volume of air at 7000 RPM than at 3000 RPM and it needs to make it efficiently.
The turbine side of the turbo needs to be addressed differently. Gasoline exhaust gases are HOT, in the range of 1000-1400ºF when under load, but they are of a comparatively lower volume to a diesel. The turbine can be sized to take advantage of this heat. Hot gases will expand, and by keeping a small amount of back pressure to the engine, the cylinders will be filled completely. The hot gases have only one place to go: through the turbine. Any restrictions after the turbo are a waste and only cause slower spool up times.
Quick Summary <TABLE cellSpacing=10 cellPadding=0 border=0><TBODY><TR><TD vAlign=top width="50%">Diesel Low RPM
Low Boost
High Volume of Air
Lots of Warm Exhaust Gases
Slow Spool Up
Almost No Back Pressure on Throttle Close

</TD><TD vAlign=top width="50%">Gasoline Variable RPM
High Boost
Variable Volume
Hot Exhaust Gases
Quick Spool Up
Hard Back Pressure on Throttle Close

</TD></TR></TBODY></TABLE>
The information is provided to educate turbo owners. The differences between gasoline and diesel turbos is significant. This is another reason to have your turbo rebuilt by a shop that works with gasoline turbos. Some diesel shops would be impressed by working on a turbo for an exotic car and would be willing to do the work, but they are typically limited with their testing ability. If the shop can only balance your turbo to 30,000 or 40,000 RPM (where diesels operate), it really doesn't do much good because your turbo is operating at double, triple, or even four times that speed. Try to get it balanced to at least 70,000 RPM at minimum. In addition, the oil-to-air pressure differentials of a diesel turbo and a gasoline turbo are significantly different. Pay the extra money and get the work done by an experienced shop.
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lol just read it.. so it looks like i will cook those oil seals in a heart beat and turn my buggy into a mosquito fogger.. a rebuild kit for my turbo is about $100 ill see if I can get some high temp oil seals..... so anyone know what the rpm range of this turbo will be on a gas engine?

 

Go talk to ElPolacko.

 

hes in my neck of the woods.. not a bad idea...

 

Go to evil bay and search turbo... The chinese are making brand new T3/T4's that are selling for $125. You can also get EVERYTHING needed to put a turbo setup together for just a couple hundred bucks.

Dont give me any crap for that... 90% of all automotive turbo's now come from china... 100% of our trans gears come from india

 

Here's the best spot to start...

www.theturboforums.com

 

You need a compressor section that delivers the flow and pressure you require, and that needs to happen in the right portion of the compressor's flow map. Then that compressor section needs to be driven with a turbine section that has the right size and AR to make that happen without poor or delayed response at one extreme, or excessive restriction at the other extreme. Bottom line, maybe(but not likely) part of that turbo wold work for you, but there is no way the unit is going to work well on your 305 as is.

 

my suggestion is if you want to run that as is, use a pressure bonnet with a blow off port large enough to keep the intake side at about 7 to 9 lbs if your motorhome has an automatic trans then throttle off conditions will not be as much of a problem. I would start at about 5 psi and work up slowly.

The main problem is that turbo doe not have seals in it for any vacuum use.

 

Remember both engines are just air pumps, the main difference is the gasoline engine uses a throttle body to control engine speed, whereas the diesel uses a fuel curve.

A 6.2 litre diesel engine @ 3000rpm pulls the same air as a 5.0 litre gasoline engine at 3720rpm


If you expectations are reasonable this swap should be OK

The biggest issue would be fuel management , if your 305 is injected it would be quite easy to accomplish.
All you need to do is keep the Airflow meter in front of the turbo, and keep the O2 sensor in the exhaust [ And don't get too ambitious with the boost, 6-8 psi max ]
If it still runs too lean fit bigger injectors

I have succesfully swapped over a turbo from an LD28 nissan diesel to a L20 nissan six [ and vice versa as well ]
it was a relatively trouble free conversion

An intercooler really helps [ it's only plumbing and no more difficult than an exhaust system to fit ] but never use an intercooler on a suck through system, as the air fuel mixture is a potential bomb .

 

well if I do run it.. it will be a blow through set up.. with a preassure box for the carb.. no fuel infection.. my budget won't let me.. I am cobbling this together with stuff I have. now back to these figures.. if the 305 is moving the same amount of air at 3750 that a diesel is at 3k with say a 4k redline that to me would say that the powerband of the turbo would be peaky and unusable? yeah?

 

I am far from a turbo expert, but I can tell you I am utilizing a Holset from a late model Dodge Ram Cummins with no modification on a four cylinder 2.5 liter descendant of the old Pinto engine, and it works quite well! Peaky?, maybe, but with such an increase in USABLE horsepower; it's perfectly fine as a daily driver if pressed into such service.
Carbed blow-through is do-able, but really a PIA to sort out in my opinion; even an inexpensive aftermarket injection system would really simplify things, and give adequate monitoring and protection.
As an old friend states, "your results may vary".
Paul

 

A blow-off valve is simpler and cheaper way to control boost than a wastegate. The down side with a blow-off valve is the chance the compressor will go into surge. You don't want that. The only way to know how likely that is to happen in this case is to have a flow map for the compressor and do the math, or just do all the work to try it and see what happens.

Without figuring some things out what you'll end up with putting this turbo and engine together is a total roll of the dice. It's no different than blindly combining a random camshaft, carb & intake, and ignition advance curve. What you end up with will probably run, but how long and how well is entirely a matter of chance. That has been proven many times. There are plenty of modified engines that are little if any more powerful than a comparable stock engine. And at the same time, those engines are less user friendly then they were before being "upgraded".

You wouldn't install a ring and pinion without knowing what ratio it was. The same is true of turbos. If you are going to do a turbo install either read and understand some books on the subject, or follow what has been done on turbo installs comparable to yours.

 

In 77 I was building a 270 GMC for my 32 Ford five window. I had an old Corviar turbo I got for $19. To little for a 270 so I picked up another one for $50 and some exhaust tubing and began playing. Very educational and rewarding. By the time I was tired of it I had pretty much blown up every Corvair turbo in every junk yard near here. But it was fun and I think you should just jump in. At least there are lots more turbos in junk yards these days.

 

Some of the above information is wrong, diesel engines produce substantially higher exaust temps.
(Gasoline's chemical structure is not as heavy has diesel's structure, resulting in a fuel that burns at a lower temperature range. In the end, the exhaust temperature from gasoline combustion is only between 700 and 1,100 degrees Fahrenheit.)
(Diesel In contrast, the heavy molecular structure of diesel fuel requires more heat to trigger combustion within the engine chamber. As a result, the exhaust temperatures emitted are particularly higher than gasoline, ranging from 1,000 to 1,200 degrees Fahrenheit.)
On top of that diesel has a higher BTU value 147,000 BTU vs 125,000 BTU, diesel turbos tend to turn around 80,000 rpm under peak load at around 8 psi, but diesel has a higher exaust pressure due to heat and compression. I would gamble that a small diesel turbos like the units off a GM/AM general 6.5 TD would work fine for a 305 and would probably be decent for mid range power if the wastegate was setup properly. Both work on the same principal but diesel turbos tend to have larger turbines on the exaust side because of the higher pressure involved in the cylinder heads so it will spool slightly slower, but on the smaller 6.5 TD it shouldn't be a problem, and the integrated wastegate could make for a easier install, as long as your oil system can move enough to keep up with the oil line to the turbo and you use a oil cooler in the system to protect your oil temp (gasoline engines usually have a 5 quart system instead of a 3 gallons) I don't see why it wouldn't be fine for 5-7 psi boost on your 305 as long as you have a good boost controller setup for ignition and wastegate operation.

 

@Patrick Jones
You understand that this is a 11 year old thread?