2H (junkyard) Turbo

[gifu]

somewhere i read about someone somehow installing a turbo taken from another car (thunderbird? supra?) and grafted onto a cruiser diesel?

seeing as my L634t has a garrett T3 turbo (thanks steve), and a Thunderbird has the same... I would think this might be a good turbo to try on the 2H and/or 3B.

for those on a budget, of course.

another question... if you are turboing a non-turbo diesel... that means the IP does not have the ability to compensate for the increased air, right? on a factory turbo diesel, there is a pressure line running from the intake manifold to the IP, which forces the IP to fuel-up when the manifold pressure increases. so, is kinda of a limiting factor when turbo-ing non factory turbo's?

just thinking outloud.

 

[theSherpa]

The 6AT's T3 is .45 trim .42 A/R compressor with a .48 A/R turbine housing. Some T-Birds came with that, and some came with a .63 A/R turbine housing, which will flow more air but spool more slowly, FWIW. The smaller one should behave about the same on a 3B, as the 6AT is also 3.4 liter. The 2H is 4 liter, so that turbo would spool quicker and flow less air at higher RPM, so EGT and gearing would have to guide that choice. H55F would tolerate smaller turbo, as you'd be running the motor slower (less airflow) at any given speed. The guys *running* 6AT's (leaves me out ) seem to feel like turbo doesn't spool until the motor turns some revs, so I've been wondering if, given that you were geared to keep the motor at lower revs, running a smaller turbo with a big wastegate (so avoid unnecessary restriction at higher RPM's) would work better on the 3.4 liter motors. Maybe a big T2 (like on TDI Golf/Rabbits), or a .36 A/R exhaust T3 with maybe a .40 trim wheel (that exhaust A/R is rare, I think). In other words, get the turbo to spool early, don't spin the motor to 3000 as much, and let the wastegate dump excess to keep turbine rpm down. Dunno...

This is for 'dre: he, he, he...

 

[theSherpa]

P.S. the 6AT's rated power is at 3600 rpm, and I think the turbo is sized for 2800-3600 rpm (WITHOUT an intercooler, mind you) ... which is outside the motor's comfort zone for fuel economy and the driver's comfort zone for noise, IMHO. That's part of my thinking on the smaller turbo idea...give up HP on top for torque down low. Probably require an intercooler to keep intake air temp, and therefore EGT's, down.

 

[gifu]

are the housings and/or flywheels marked in any way? or does one need to know the exact year make model of the donor, then research what turbo it has?

(just to clarify... cause i've never gotten a solid answer... does the waste gate open up at a certain pressure? so as not to overpressure the system?)

 

[theSherpa]

All the housings I've seen are marked...might be some that aren't. The turbine wheels are all the same on T3's. The compressor wheels are not marked that I'm aware of, but the compressor wheel trim is determined by measuring the major and minor diameter of the wheel and applying a formula, or comparing the dimensions to this:

http://64.225.76.178/main.htm, which is from this:
http://64.225.76.178/main.htm

Yes, wastegates open (dump exhaust pressure from the area between the exhaust valve and turbine wheel to the exhaust pipe) as pressure builds between the compressor wheel and the intake manifold...they open progressively, and they are fully open at the pressure desired. A turbine housing with an integral wastegate (such as the 6AT's T3) generally can't flow the entire exhaust volume at the release pressure, which is why higher performance turbo setups (race, big trucks) use a large wastegate valve in the middle of an exhaust-pipe sized pipe path between the intake of the turbine and the exhaust pipe. Google up some high-performance turbo installations (and look around at the site above) to see what I mean. Now, do I know that the T3's wastegate can't flow the mind-blowing 300 CFM that the 6AT puts out at 3600 rpm? No, but I'm sure it's a restriction. Don't know if it would make a real difference, just throwing it out there.

are the housings and/or flywheels marked in any way? or does one need to know the exact year make model of the donor, then research what turbo it has?

(just to clarify... cause i've never gotten a solid answer... does the waste gate open up at a certain pressure? so as not to overpressure the system?)

 

[theSherpa]

I should have made the point that the compressor wheel trim is a function of the ratio between the major and minor diameter of the wheel...but is only relevant to compare different wheels within a given series of compressor housing (like T3). a .45 trim T3 wheel is smaller than a .45 trim T4 wheel, and will flow less air...T4's are bigger turbos all around, and T2's are smaller turbos. That's the nice thing about Garrett turbo's...this info is available is much greater detail than for the CT Toyota turbos or KKK's of European cars. And, at places like Turbonetics, you can buy parts or turbos built with the combination of parts you want (and think will work for you). They are complex little beasts, and this is just the tip of the iceberg of variables that can (and do) exist in turbo configuration and affect a turbo's ability to do what you want on a given engine. The OEM's implementation of turbos has typically been very conservative and non-optimal, though it's getting good lately.

 

[theSherpa]

The housings on the Chrysler T3's you mention have the same A/R as the T3 that comes on the 3.4 liter 6AT, and yes, I would expect them to behave similarly on the 3.4 liter 3B. I said that. I also said that the 2H is 4.0 liter, which according to the same math that makes the T2 too small for 3.4 liter makes that T3 too small for the 2H. How is that "the running characteristics...are the same"?? Of course, both guys actually driving the 3.4 liter 6AT's have noticed they don't spool until you rev them...I've driven one of them, and experienced that myself (it was a laggy bitch at the time I drove it). A smaller turbo WILL spool quicker. The math is based on the mass of air moving through the motor, which is determined by the VE of the motor at the RPM and boost pressure you're trying to size the turbo for. How perfect would that T3 be on a 3B running 5000 RPM? Not. If you gear the 3B or 6AT'd truck to run 1800-2000 rpm at cruise, a T2 off a Rabbit/Golf would be in it's happy zone, according to the same math. That was my whole point, and it's not wrong. Yes, the turbo would be overdriven at 3600 rpm, but if you don't run the motor that hard, who cares? That's where the wastegate part of my post came from...dump the boost you don't intend to use to keep from overrevving the turbo.

My comments were entirely directed at the 6AT/3B motors we've got, I never intended to suggest the T2 would be practical on the 2H, though dependent on the gearing and RPM you used, it could be. If you run these motors through the Turbofast calculators, you'll see that it suggests an even bigger turbo than what the 6AT comes with (which is the same as the Chrysler one you suggest)...the calculators are not a determinant, and those who wrote them will tell you that. I never said that the T2 would be ideal, I used the word "maybe".

Ever look at how wide the range of sizes of turbos was used on STOCK Dodge Cummins with the 6BT, much less the aftermarket stuff? This is all about tradeoffs, there are few absolutes.

Don't think I haven't read this stuff...I haven't tried it on my engine/truck (it would have to actually run!), but there's a lot of prior experience published that suggests that my perpective is not completely off-base. Go spend some time reading the forums at www.turbodieselregister.com and see how many calculators those guys use.

Steve

Firstly, and I could be wrong, I thought the 6AT was a 5.9L not a 3.4L like the 3B.

Secondly, the turbo that you want for a 3B (someone smarter than me has done the actual math on this) is a Garrett T3 from a Chrysler Lebaron, K-Car, New Yorker, or Mini-van. The ratios are .48 and .42. There are a few guys in our club running this turbo, and in proof to the math they say it is the perfect turbo for the 3B. Given that the running characteristics of the 2H are so similar to the 3B, I would say that the same turbo would apply.
Going with a ".36 A/R exhaust .40 trim" from a rabbit would be way to small for the 2H application. It would spool up way too fast and not give you any high end...as in highway boost. Also, running that fast all the time you run higher wear and the risk of it grenading that much quicker.

This is a useful page to determine your turbo needs;
http://www.turbofast.com.au/javacalc.html

Craig.

 

[theSherpa]

The wastegate controls max boost to the extent that the alternate path it provides can flow the excess...if you put an internally wastegated T2 on a 6BT in a Dodge, you'll get huge boost with the wastegate wide open, right before the turbo explodes.

Assuming the compressor wheel and housing was size pretty close to begin with, the way to get more boost at lower RPM is to use a smaller turbine housing and/or wheel, so it'll spin the same RPM with less flow through it. If the turbine side is already on the small side, then a bigger compressor wheel might give you more airflow (which matters more that boost pressure itself) at lower RPM.

An intercooler will lower boost pressure a bit, given that everything else is the same (if you cool air it lower the pressure, Boyle's law or something), but the increased mass of the cooler air more than makes up for it. Intercooler's don't increase lag appreciably because when it's full of air all the time...when you increase the pressure on the intake side of the intercooler, it pretty instantaneously increases the pressure on the other side (press one side of a balloon, or operate a hand air pump, to see an example of this). Unless it's way too restrictive to flow the air at the increased pressure, but that's unlikely.

6AT's wastegates are set at 15psi.

Steve

so... does the wastegate control the max boost? Not that I know what mine is getting to. Is it adjustable for more boost?

And... would it be as simple as changine the compressor wheel to get more boost at lower RPM?

And... will the addition of an intercooler change the boost at all? Will there be more lag, as the turbo is, essentially, a lot further from the intake?

And... uh... no, that's all.

 

[lumpy70]

Easy, easy there Sherpa. I wasn't trying to step on anyone's toes or sound like a know it all. I apologize if I did either of those things.

I was merely referenceing the experiences I, and some other members of my club have had.

As to "running characteristics", I was just saying that the drive in a 2H cruiser feels the same to me as a 3B cruiser, as they are both similarly powered. Of course displacement is different and one turbo might not be as perfect as another, but close enough to work well.

As for the Rabbit turbo running at 2000 rpm, I don't know anyone who runs their cruiser that low on the highway. At 2000 rpm, the 3B is only making something like 50 HP. As a group, we cruiserheads tend to be the guys who are running bigger tires than stock, putting on heavy aftermarket accesories, and higher gearing (4.11's and 33's will give you 2400 rpm at 100 kph).

All I was saying was that I didn't feel like that was a realistic PRACTICAL application of how people actually run theri trucks.

Again, I didn't want to turn it into a big thing, and most likely I was just feeling peevish for some other reson and it came thru on the post. Apologies.

Craig.

 

[theSherpa]

Non-turbo injection pumps don't have boost compensation, so you get a choice...turn them up so you have all the fuel you can use under boost, and live with the smoke (and EGT's) from the excess fuel when off-boost, or adjust the IP for smoke and give up potential power under boost. That's the biggest hangup with turboing 3B's and 2H's, no boost compensation built into the governer on the pump...though AXT or somebody in OZ sold boost compensators for those IP's at one time.

Boost compensation is actually an aneroid (diaphragm and linkage) that *limits* max fuel when off boost, but backs off under boost pressure to allow max fuel (known as "full fuel" in IP lingo). Altitude compensation works similarly...limits full fuel when ambient air pressure goes down (like at altitude).

Steve

so... what about the IP? can a non-turbo IP deal with the increase in air?

what about the piston-skirt cooling, or whatever that is?

 

[lumpy70]

I think a really cool setup would be a two-stage system using a rabbit turbo like Sherpa suggest for the low rpms, and a bigger one (like a Supra CT-26 or something) that gradually takes over as rpm increases. That samves the smaller turbo from exploding as exceleration increases.

I really have no idea how to do this, so someone much smarter than me would have to figure it out, but there are cars out there running 'sequential turbos', and that is pretty cool. I think that they have a mechanically interlocked wastegate between the two turbos or something tlike that.

Craig.

 

[theSherpa]

No worries. My currently 2F'd H55F'd FJ60 with 3.73's and 33's runs 2300 rpm at 70...and it's getting at least 35's, and likely 37's in the future. 37's with the above config will run 2000 rpm...I know Gifu is planning an H55F. 4th gear will be 2500 rpm, so 5th might become flatland gearing, I have no problems with shifting down for a hill. That's my point...I'm looking at ways to make more power down low, because diesels are more efficient and happier at low RPM, and turbos properly sized can make that possible. In the 1970's, big trucks got 235 horse from a 672 cu.in. motor running at 2100 rpm. Now they get 400 from that engine (now 728 cu.in.) from 1300-1700 rpm, and 350 is available at 1100 rpm. Yikes! That's using variable geometry turbos that are small at low rpm and get effectively larger at higher rpm, pretty complex electronics/4-valve heads/complex injection, but it shows the possibilities. What I'm saying doesn't jive with common knowledge, I know that, which is why I'm bringing it up...

There's a big world outside of calculators, OEM equipment and "the way it's always been done", and I like exploring it.

Apologies entirely unnecessary, because I am NOT an expert.

Steve

Easy, easy there Sherpa. I wasn't trying to step on anyone's toes or sound like a know it all. I apologize if I did either of those things.

I was merely referenceing the experiences I, and some other members of my club have had.

As to "running characteristics", I was just saying that the drive in a 2H cruiser feels the same to me as a 3B cruiser, as they are both similarly powered. Of course displacement is different and one turbo might not be as perfect as another, but close enough to work well.

As for the Rabbit turbo running at 2000 rpm, I don't know anyone who runs their cruiser that low on the highway. At 2000 rpm, the 3B is only making something like 50 HP. As a group, we cruiserheads tend to be the guys who are running bigger tires than stock, putting on heavy aftermarket accesories, and higher gearing (4.11's and 33's will give you 2400 rpm at 100 kph).

All I was saying was that I didn't feel like that was a realistic PRACTICAL application of how people actually run theri trucks.

Again, I didn't want to turn it into a big thing, and most likely I was just feeling peevish for some other reson and it came thru on the post. Apologies.

Craig.

 

[theSherpa]

Now you're talking. This gets done a LOT in Dodge Cummins world. It's hard to grasp the plumbing nightmare that makes this work, but it does...there's guys that have gotten 700 hp from a 160hp stock 1st gen 6BT doing this...it works.

http://www.cumminsracing.com/mainpage.htm
http://www.cumminsracing.com/images/rightside.JPG

I think a really cool setup would be a two-stage system using a rabbit turbo like Sherpa suggest for the low rpms, and a bigger one (like a Supra CT-26 or something) that gradually takes over as rpm increases. That samves the smaller turbo from exploding as exceleration increases.

I really have no idea how to do this, so someone much smarter than me would have to figure it out, but there are cars out there running 'sequential turbos', and that is pretty cool. I think that they have a mechanically interlocked wastegate between the two turbos or something tlike that.

Craig.