Thought I would explore my options a bit.

I have a carbed 351w truck, and somewhere in the process of purchasing some heads and a camshaft, I thought, why not keep the stock cam and add a turbo. So I figured I would get thoughts on it. I have a month left that I can safely return the camshaft to get a full refund, so I have some time to think it over.

I am looking for mild and simple. If I can get away with no intercooler or timing retard system then I would be happy. Not looking for massive hp (however I am looking for torque just because its a truck), just something better than stock that puts a smile on my face.

My initial thought is to use a turbo off a diesel truck, as they are designed for low end torque (or power production) any thoughts on that? I have read a good book on forced induction, but would like thoughts on actual matching of different sourced components. Feel free to spell everything out or I will just end up asking the question anyway. All thoughts appreciated, thanks

 

I suppose it depends on the application of the original turbo. The size and design of the vanes will determine what rpm it makes boost and how quick. A smaller turbo will give you boost quicker, but less is available due to smaller size. I would get ahold of a tech line and talk to people. Get some names from people that offer kits for Mustangs or such and see what they recommend.

I had put thought into a twin turbo set up for my 352 FE. I can make the manifolds and plumb it, no problem. I was thinking turbo's from a turbo coupe T-bird. Small and with two the volume would be there. It's an idea, and with some time this summer, maybe I will start to collect pieces.

 

Junkyard Turbocharging?

I fit into that category.

There is a simple math formula for calculating approximately what turbos you should use.

( your engine displacement * redline ) / (donor engine displacement * redline) = X

X = the number of that type of turbo you need for your application.

For example.

You're in the junkyard, staring at a turbocharged Dodge Daytona 2.2L. These cars redline at about 6500 RPM or thereabouts. Look at the tach.

So we have...

(5.8L * 5500 rpm) / ( 2.2L * 6500 rpm) = X

31,900 / 14,300 = x
2.2 turbos = x

You need 2 dodge daytona turbos for your application.

On my twin-turbo 500cid stroker motor, I did the same, using two grand national turbos.

(7.5L * 5500 rpm) / (3.8L * 6500 rpm) = x
41,250 / 24,700 = x
1.67 turbos = x

So in my case, I need almost 1 and 3/4 grand national turbos, so I decided to round up to two turbos, since the likelyhood of me going past 5500 RPM is real.

This is just an approximation method, not taking into consideration inlet and outlet dimensions, angles of exhaust manifolds or headers, length of tubes and method and effectiveness of intercooling method you choose. But it at least can get you into the ballpark, so while standing in the junkyard within two minutes you know how much stuff to take out.

You get extra points for "showing your work" as I often do with a sharpie, I write it out right on the windshield

Good luck!

 

Appreciate it.

 

I can appreciate you trying to spend as little money as possible, but you're asking for trouble. Stock pistons are usually cast, and they will melt if you add a turbo. Even hypereutectic pistons aren't good for use with a turbo. Forged pistons with a reverse dome would be the ticket. No intercooler or timing control? Also engine melt down. You would have wicked bad detonation with the increased cylinder pressure and temperature. Compressing air makes it hot. Engines don't like hot air. Then there is the fuel management system. You have to increase the fuel pressure to directly correspond with the increase in boost. As far as the cam goes, turbo engines would work with a stock cam, but they make special grinds for turbocharger use.

 

Gotchya.


Interestingly enough there are quite few people using stock shortblocks and making decent hp and tq under boost, how long it would last is another story. I would probably have to use some type of boost reference for the fuel to keep up, thats not too big a deal. Appreciate the response.

 

Yeah, there's some in the Mustang crowd with supercharged stock engines. We're talking forged pistons in those stock 5.0 short blocks too. They also use intercoolers, FMU's, and timing retard to make them run right.

 

I was thinking about the gen 1 lightnings, there are a few running stock shortblocks and running quick in the quarter. There was also some mention of the later mustangs around 93 + (I believe that have cast pistons) putting down some decent numbers as well. I know what you mean though, all about the tune and components that keep it in line.

 

frederic


What exactly did you have a twin turbo 500ci motor in? Did you get any hp and tq numbers? Later

 

JW, my thoughts are that it can be done and has been done....

you will however need to go with twin turbos...preferrably the
Thunderbird turbochargers from the 2.3L.

Go with a set of motorsport headers and install them with the exhaust facing the front....and plumb them into the turbos....then you can route the exhaust under the headers, and down the normal path...

The use of thermal barrier coating is recommended.

then plumb the intake tubes accordingly.

pop off valves will most likely be plumbed by a T connection for vacuum signal.

Fuel management will probably have to be a haltech unit.

Larger motorsport injectors along with the MAF conversion.

 

Truck: https://www.ford-trucks.com/user_gal...=36591&width=1

 

How irritating, by the time I finished typing out my lengthy reply, I timed out, had to sign in, and my post was magically gone. Hopefully I can type faster this time...

Anyway.... JW Taylor...

The engine I am building is not complete, so I can't give you any hard numbers as of yet. But, I can say if its anything at all like the twin-turbo 451 mopar stroker I built for my 75 Dodge D200 when I had it, just know that I shredded the rear (Dana 70) the first time out. I actually expected the transmission to explode first, and not sure why that didn't happen.

The engine I'm building will go into this:



The idea is to fully load the truck up, and watch turbo-cummins Dodge Rams get smaller in my rearview. I am replacing a tired, high mileage 351W, not that it makes any difference what is there now. It won't be for long.

My build here has to overcome a lot of things. First, as you can see the recipient of this engine is not light by any means. I weighed it unloaded, both tanks full and I was six pounds short of 7000. I thought that was ridiculous considering it does not have air conditioning, any emissions equipment except the cat, no hitch and is single rear wheel, but the scale is certified by the state of NJ so I guess it has to be correct. Yes, she's heavy.

The second thing I have to overcome is emissions... while I have her registered as a commercial vehicle (due to a loophole in NJ state registration) I only have to pass an idle test, but it is something to take into consideration when building motors and turbocharging. Lastly, I also want "decent" mileage. "Decent" to me means low double digits. I'm not expecting 30 miles to the gallon. I just can't afford five

I'll stop being a windbag and respond to some of the comments you're received thus far.

First, Steve is correct in that the stock pistons are not suitable for a boosted engine, and trying to reuse them puts your engine reliability at risk. If you're cheap, go for it, but know you'll probably need a new engine at some point.

I will disagree however that hypertuerics are a bad choice, because they are a good choice in a boost engine for many reasons. Here is an analogy for you...

Take an empty mayo jar, remove the lid, and put it on the driveway lip down. Now stand on it. The mayo jar will survive your weight. Now have someone hit the side of the mayo jar with the claw on a big framing hammer. The jar will shatter, and you will drop about 6" closer to the earth.

In this analogy, your body weight represents the normal forces a piston willl experience inside an engine, the mayo jar is a hypertueric piston, and the hammer claw is a shock load - detonation.

The key to using hypertueric pistons in a forced induction engine is to avoid detonation. You can do this many ways... timing, intercooling, lowering the compression, water injection, etc. But if properly tuned, hypteurics are just fine. The problem I see over and over again is people not tuning their combination properly, or being unrealistic. But unlike cast and forged pistons, Hypertuerics do not radically change their size or shape when heated, therefore you will have better ring sealing and less opportunity for piston slap down the road. In a highly loaded engine, this is an important thing to strive for. You want the explosions above the piston, and the oil below.

Speaking of oil, when building your turbocharged engine you have to take into consideration the extra oiling requirements of the turbos, as well as the extreme heat you'll be introducing. On my last project, a twin turbo mopar 451 stroker (also for a big pickup - 75 Dodge D200), the turbos glowed a dark, dull cherry red color. That is hot. This heat goes right into the oiling system because the oil has to circulate through the bearings of the turbos, so you have to use a large oil cooler. For this project, I scarfed out of a junkyard a huge oil cooler off a Kenworth. Was a lucky find really. Anyway, you'll also need at a mininum a high volume oil pump, if not drysump.

Capone mentioned ceramic coatings. He provides good advice here. Coating across the piston tops, over the edges down to the top of the first ring landing area is important. You want the heat in the chamber, not in the hardware, so coat everything. Coat the intake and the exhaust valve heads as well, and the surface area of the head facing the combustion as well. Also put some effort with your dremel to make the chambers smooth and free flowing, casting flash and odd bumps you often find in head chambers do nothing but act as a beacon for detonation. Remove it all, make things smooth, and coat it well. Be sure to recalculate your compression ratio after removing any material in the combustion chamber, of course.

Regarding compression, one of the mistakes I often see is people are a little over-zealous with the boost on normal street engines in the 9:1 and up range. Even with o-ringing the block and heads, you cannot run radical compression with pump gasoline on a high compression engine. Diesel fuel yes, gasoline no. So you have to accept an approximate limit of 8lbs of boost on a street engine, or increase the boost and really lower the hard compression ratio of the engine.

How low is low? The engine I'm building now will have a 6.5:1 compression ratio. The reason for this is in the past several friends and I theorized and have proven with a dyno that more torque/power can be made by running a ridiculously low compression ratio and rediculously high amount of boost - in the 30lbs range... and yes, pump gasoline.

If you do the math, you'll find that for a given combination of rods and pistons, your rods will experience less of a load at 4000 RPMs with 30lbs of boost, than at 6000 RPMs with 5lbs of boost. Your pistons and rods will thank you if you think like this. Your headgaskets might not, but that can be resolved by using quality bolts like ARP, and o-ringing the block.

Your best friend in all this will be your knock sensor, and how it controls your timing (retarding as necessary). Too much timing under boost will give you detonation, and a nice shockwave that will break parts. Your knock sensor is the key to this. And don't just use any knock sensor. You have to find one thats appropriate for your block, and piston size. Knock sensors are essentially a microphone, tuned to a specific frequency. A 500cid engine, under detonation, will "ring" at a particular frequency. A honda 1.6L engine, under detonation, will "ring" at a different frequency. Its important to know this so you chose an appropriate knock sensor.

What EFI system will you be using?
The drawback to this is you won't enjoy neck snapping torque off the line unless you rev a bit in order to spool up the turbos... but for my purposes thats most acceptable. I have zero intention of running my bloated crewcab down the 1/4 mile... but instead if I'm doing 75 with 6000lbs of bricks in the bed and hit a 6% incline, it would be nice to maintain that speed. What are you building for? Highway or 1/4 mile?

Intercooling offers a fun debate. I know a guy with a Buick Grand National (v6 turbo) that is experiencing better performance after he removed the intercooler, and redid the code in the ECM so that the 7-th injector (cold start injector) on his engine joins in the on-the-road fun. No intercooler, plumbing is easier, less weight, less hassles. But you have to watch for detonation, Capone is spot-on.

And there are many types of intercooling too... none of course as my friend does, but also air to air, water to air, water or alcohol injection, etc. Its a big list actually, and your choice may be a combination of the above if you really want to push things. It really depends what you are building your engine for.

If you're building a highway cruiser, that will have a fair amount of airflow most of the time, air to air is very effective. If you're drag racing on the other hand, air to air generally is effective about half way down the track, then the intercooler becomes heat-soaked, and actually heats the air rather than cooling it. You may call it an "interheater" at that point. This is why a lot of the non-pro doorslammer guys run water based intercoolers, or run the airflow through an igloo cooler with a block of dry ice in it. After each run, they dump the "stuff" out and replace it with cold water or another dry ice block. For short bursts of power like drag racing, its extremely effective.

Water injection has been used on and off by the OEMs. VW did a lot of work in this area, even of silly things like VW Rabbits (GTI). Remember that the post-turbo air temperature can easily reach into the 300-400 degree range, way above the temperature that water turns from a liquid to a gas. So when the water is sprayed or injected into the air charge, it immediately boils into steam. By doing so, it absorbs some of the heat (energy) thus reduces the temperature of the air charge. Water injection also really keeps the combustion chambers clean. Your pistons and valves will be very shiney. The drawback to a water injection system is that it runs out eventually, so you have to pay attention to water supply tank size and keep it full.

Alcohol injection works the same way - the alcohol goes from a liquid to a gas at those temperatures as well, and has the additional property that it burns too. Alcohol is also a "dry" liquid, much like gasoline, so on my last project (the mopar mentioned above) I chose to inject a 50/50 mix of distilled water and isopropal alcohol.

 

One big problem of going the junkyard route is a lot of the parts you will need don't exist. You will have some fabrication to do and there isn't really a way around it.

For packaging, I've chosen to make all new accessory brackets, and put them at the bottom of the engine, so I have room at the top of the engine compartment for the two turbos, facing forward. I don't want the turbos against the firewall, but I don't want them against the hood either - I like the paint where it is. So I have to mount them about 5-6 inches from the underside of the hood, or lower, so I have room for thermal insulation on the inside of the hood, and so they have some airflow. Turbos can get really hot as well as the downpipes.

Camshaft selection is very easy. The only rule you need to worry about is having no overlap. A "towing" or "RV" cam is an excellent choice, and it won't break the bank either. More lift is good because you can get more air into the engine that way, but paying attention to overlap is by far the most important thing. You do not want your precious boost going out the exhaust valve

Beware of "Turbo Grinds" that cost significantly more. I'm sure some companies have put a lot of engineering effort into making a good cam for forced induction engines, but sadly most of them have not. I've seen only a few turbo cams, and they measure out just about what an RV/Towing cam, so maybe I'm jaded.

Also, think about RPM range. For the street, you really don't need 7000 RPMs. My twin turbo mopar stroker proved that a few years ago. Redline was coded into the ECM at 4700 RPM, and the dana 70 still splintered into tiny pieces.

Lower RPMs also put less of a mechanical load on your rotating parts. As you know the force upon a piston changing direction at TDC (or BDC) is exponentially related to every 1000 RPM you add. Lower RPMs increase reliability.

 

My apologies for a really disjointed post... I got it typed out before I timed out, then it was too big so I tried to cut and paste it into two posts, and apparently I can't even do that correctly. So, hopefully you guys can read through the disjointed writings. I'm happy to clarify anything... I just can't retype that whole mess for a third time... LOL

 

if you time out, use clipboard to save your stuff relog and then paste it back out of clipboard....

The junkyard turbo method I'd think would be easier if you had engines closer to the donor engine.
The 2.3L SVO Turbo 'Stangs would be great for donateing to a Ranger with a 2.3L for example.
Acually went through some of the pre-planning on that. Optimally I'd need an '81 to '82 since my truck is an '84. Those year model stangs used a draw-thorugh turbo and a carb, from '83 to the end of them in 86 they were injected. '85 is when they started injecting the 2.3L in the rangers.

I'd think that going to a turbo maker getting the turbo new used or remanufactured turbo, for your piticular application then useign the junkyard to supply the rest of the parts would be easier....but less fun.

By the way, 351W boosted by 2.3 Tbird/mustang turbos would be cool. Use heavy gaskets though, those little engines in the stangs turned out aournd 225hp, think that is what the 351 turns out.

You can try runing the turbos at high boost but using it to pressurize a larger volume of air to a lower level of boost. This may also minimize the "turbo lag", or maximize it.

anyway....


have fun....
bdraft