Compound turbo 3B

[cody c]

Hello, Ive been perousing the search function for a while and havent found the info Ive wanted so Im starting a new thread, hopefully those with a bit more "know" can pipe up.

I have a 3BT/H55f/ 60 series axle's that are going into a JDM 4 door hilux and am considering upgrading from my merkur turbo to twins (compound).

I really enjoyed turboing my 3B with the merkur turbo, it made it much more pleasant to drive around the city, made cool noises, and it felt like a really great achievement when I first put it together. The other thing is, that aside from a little assembly, it was actually pretty easy. Buy a merkur turbo off of ebay and firgure out how to weld some steel to the manifold and exhaust, then bolt it on. Throw on some oil lines, Done.


The compound turbo's are quite appealing as well now that someone else has done it, but which turbo's to use, what housings etc. is still quite confusing. The last thing Id want to do is order some turbos and rebuild kits, bolt them up and find out they dont spool or spool to early and have to redo flanges and exhaust and try another turbo and pray it works.


So... Im looking for specifics. Enough info to accurately describe what turbo or part or housing to order new or used off the internet, and only order once, which may be a lot to ask.

I know that there is some of you on here that seem to know your turbo theories and whatcha magadgets, so lets start somewhere. Eventually we can narrow down a list for those wanting to try a compound setup, but not knowing what to use or where to start.

Thanks for any input!

 

[slowandsteady BJ]

Compounds are GREAT! Boost from idle to redline, no black smoke waiting for boost to come on, lower EGT's and the sweet sound..... oh the sound.

This is defently on my to do list as well Cody!
My Cummins common rail has compound turbos and it rocks, cant wait to do the same to the "B".

Gerg has done it. Off the top of my head I recall he needed better cooling to keep up with the extra heat and he even listed the turbos he'd use if he did it again. That info should help. His thread was called "Margaret Thatcher on a cold day" but it got renamed to something much less memorable. lol

Whatever the case check his thread out, he knows a thing or two to say the least. Post lots of info so I can copy you!


Ahhhh.... here it is.


https://forum.ih8mud.com/diesel-tech-24-volts-systems/407381-3b-compound-turbo-25psi-boost.html

 

[cody c]

Compounds are GREAT! Boost from idle to redline, no black smoke waiting for boost to come on, lower EGT's and the sweet sound..... oh the sound.

This is defently on my to do list as well Cody!
My Cummins common rail has compound turbos and it rocks, cant wait to do the same to the "B".

Gerg has done it. Off the top of my head I recall he needed better cooling to keep up with the extra heat and he even listed the turbos he'd use if he did it again. That info should help. His thread was called "Margaret Thatcher on a cold day" but it got renamed to something much less memorable. lol

Whatever the case check his thread out, he knows a thing or two to say the least. Post lots of info so I can copy you!


Ahhhh.... here it is.


https://forum.ih8mud.com/diesel-tech-24-volts-systems/407381-3b-compound-turbo-25psi-boost.html

Ive been emailing him, he just sent me some info regarding compressors and housings, but its still a little vague to me.

Im hoping to get a collaboration as to what turbo's are very close to the ideal sizing for the small and for the big turbo, then whomever else is looking to try it can source something online, order it, build and post pictures and feedback.

Edit: someone mentioned a merkur turbo with a larger housing (.63) for the large turbo. Would this be the part to upgrade a merkur turbo: http://www.ebay.ca/itm/Turbo-Compre...ccessories&hash=item3f19fe89a2#ht_2165wt_1249 (TD05 18G)

 

[langsen]

Is the end result with compound turbos much different than with a single variable turbo (VNT25, etc)?

 

[Dougal]

Compound sizing in a nut-shell.

The small (high pressure) turbo has to be able to work as a single turbo at the pressure ratio it would be running at. The big turbo (low pressure) needs to be able to shift your maximum air-flow.
From there it's shuffling up or down in the size ranges to suit your needs.

If you don't have a stronger head and seriously modified injection pump, then like Gerg, 25psi will be the max you can use. If you intercool then on the low side of 20psi will safely burn all the fuel you can produce.

So, what's your max altitude and do you have any injection pump mods planned?
These two questions set your boost. That boost is split between your turbos and go from there.

 

[cody c]

Compound sizing in a nut-shell.

The small (high pressure) turbo has to be able to work as a single turbo at the pressure ratio it would be running at. The big turbo (low pressure) needs to be able to shift your maximum air-flow.
From there it's shuffling up or down in the size ranges to suit your needs.

If you don't have a stronger head and seriously modified injection pump, then like Gerg, 25psi will be the max you can use. If you intercool then on the low side of 20psi will safely burn all the fuel you can produce.

So, what's your max altitude and do you have any injection pump mods planned?
These two questions set your boost. That boost is split between your turbos and go from there.

I dont think it is within my budget to mod my fuel pump, it will be turned up however. The injectors are in decent shape. The pump will likely never be modded unless it becomes a $400 upgrade, sounds like a $1K+ job at the moment.

It will be intercooled, probably front mount this time.

Calgary sits at 3438 feet, most of the off roading terrain will be a couple hundred feet higher, but 3500 feet would be about average.

My 3B is apparently "lower" mileage, at approximately 120,000 kms.

Im ok with 20 or 25 lbs of boost max, my goals are to find a turbo that spools quicker on low rpm, with a fairly smooth transition to the larger compressor. The merkur turbo makes around 15 psi presently without the fuel turned up. I understand that there are risks to the longevity of the motor by doing this but that is an acceptable risk in my logic. If it drops precups or has problems with the top end then Ill be saving up for a high nickle head I guess, but I wont be towing up hills at high boost or heat or running it like that for long periods, just in the passing lane now and then.

 

[slowandsteady BJ]

You are on the same path as me in terms of total boost. A lot of guys run compounds to get crazy power but that wouldn't be the best idea an a little IDI 3B. I too would build a compound system for efficiency and drivability. So long as you "cap" the boost a a reasonable figure a compound setup should be easier on the motor than a single. I say this because EGT's will be more consistant and there wont be a power surge when boost finally kicks in.

Regarding the Variable Geometry Turbo mentioned earlier..... There is a guy here on the Island building a 1HZ with a VGT. He isnt finished yet but when he is it'll be nice to see how it turns out. I suppose its kind of old school vs. new school. I think the ol' compound system fits our old cruisers a bit better plus there is the cool factor to consider.

One thing that is important is a brace from the turbos back to the block. There will be a lot of weight hanging off the exhaust studs if this isn't added. I'm sure you have thought of that though, Cody and I look forward to seeing your fab skills on this setup.

 

[Dougal]

3500ft means you'll have about 90% of the air density as sea-level. So you need roughly 10% more boost and to make 10% more boost from 10% thinner air means your turbos are working about 20% harder.

But I still think that 25psi will do the job.

As for the $400 injection pump upgrade. You can find 4BT A pumps for half that, if it were me I'd buy one and see if it'll fit.

 

[Hulsty]

Quick question, what are you trying to achieve regarding boost at what rpm and total boost? Could it be done with a single turbo or do you want a compound setup for other reasons? I have a 13BT with a single turbo, 20psi at about 2000rpm and 25psi soon after. The cooling system will need an upgrade, I have a stock cooling system with mostly new parts, If I hold 20 psi + for an extended period with EGT's around 700c+ the water temp will start to creep up.

 

[gerg]

After hearing your experience and enjoyment from your turbo, and if your not going to build your pump up, I would recomend working with what you have and maximising it. If you put a 360 thrust bearing on your turbo and maxed your fuel out, your power at 2500 would look much like mine. Building a compound set up is not simply twice the work, it is much much more and, given its going into a mini truck, you will have even less room to fit it and you might quickly regret this project.

My main goal with the compound I built was great boost down low with good top end on a budget. I hit most of my goals, but I missed and went too large on the small turbo. Overall I am pretty happy for the first version.

I am having cooling issues when I tow my trailer. Its 5000lbs loaded and when pulling long hills in the summer I am quite limited by temps. I dont like it to get much above 225F. Im hoping intercooling and an external oil cooler will help. I might have to even put the stock fan back on cus it moves so much air and my electric fan runs all the time anyway so whats the point.

The next one I build (who knows when) will truely be a compound set up pressure wise (35 psi or so), where as this one is more like a sequential. I did learn alot from it. By all means ask lots of questions if you like. I would only ask that they be somewhat thoughtful questions as opposed to "tell me what to do" kind of questions some folks ask.
g

 

[gerg]

What you posted is the compressor side of a different turbo. You would need to change out the turbine side to something like this except a .63 a/r.
< Garrett T3 Turbo Exhaust Housing AR .48 - Mercedes Benz 5 Bolt Remanufactured | eBay

Before sizing your turbos, you need to clearly set out what you want as far as rpms and boost and power goals. Once you know that, then you start matching and mapping them.

 

[cody c]

3500ft means you'll have about 90% of the air density as sea-level. So you need roughly 10% more boost and to make 10% more boost from 10% thinner air means your turbos are working about 20% harder.

But I still think that 25psi will do the job.

As for the $400 injection pump upgrade. You can find 4BT A pumps for half that, if it were me I'd buy one and see if it'll fit.

Well, $400 for a used A pump wouldnt be that bad, but it would be a "down the road upgrade"

Quick question, what are you trying to achieve regarding boost at what rpm and total boost? Could it be done with a single turbo or do you want a compound setup for other reasons? I have a 13BT with a single turbo, 20psi at about 2000rpm and 25psi soon after. The cooling system will need an upgrade, I have a stock cooling system with mostly new parts, If I hold 20 psi + for an extended period with EGT's around 700c+ the water temp will start to creep up.

I think Im looking for a reasonable method to achieve better low end boost, and have it a bit more consistent throughout the rpm band. Ive been in a couple 13BT's, they are a decent power plant.

After hearing your experience and enjoyment from your turbo, and if your not going to build your pump up, I would recomend working with what you have and maximising it. If you put a 360 thrust bearing on your turbo and maxed your fuel out, your power at 2500 would look much like mine. Building a compound set up is not simply twice the work, it is much much more and, given its going into a mini truck, you will have even less room to fit it and you might quickly regret this project.

My main goal with the compound I built was great boost down low with good top end on a budget. I hit most of my goals, but I missed and went too large on the small turbo. Overall I am pretty happy for the first version.

I am having cooling issues when I tow my trailer. Its 5000lbs loaded and when pulling long hills in the summer I am quite limited by temps. I dont like it to get much above 225F. Im hoping intercooling and an external oil cooler will help. I might have to even put the stock fan back on cus it moves so much air and my electric fan runs all the time anyway so whats the point.

The next one I build (who knows when) will truely be a compound set up pressure wise (35 psi or so), where as this one is more like a sequential. I did learn alot from it. By all means ask lots of questions if you like. I would only ask that they be somewhat thoughtful questions as opposed to "tell me what to do" kind of questions some folks ask.
g

I just realized now from your expression, that I want a sequential setup more than a high boost setup. I have no need for 35 psi boost, 25 psi across a decent upper portion of the rpm band would be plenty.

I would like 15 psi down low though, like at 1200 rpm or lower if that seems reasonable?

The thing is, my 80 has a 12 valve 6BT with a "denny T" fuel pin, and under load or at about 70 or 80 km/hr on the pavement, when I put the throttle all the way down it will bury the boost needle (needle moves to 25 psi) and it gets boost much quicker at lower rpm now, so I have been a little bit spoiled in terms of torque and horsepower since I did the aftermarket fuel pin (would only hit around 15-18 psi pre fuel pin).

The 3BT with a merkur turbo will probably feel a pinch anemic when I finally get it up and running. But the intention of the thread wasnt so much about getting me specifically the best equipment, so much as finding an average best for anyone else considering and where to source parts. I will assume that more of a "sequential" setup would be in most folks design interests while not really needing more than 25 psi, it would be more important to have increased but fairly consistent power throughout the rpm band, but especially the lower end.

I was really just aiming for a "how to compound turbo your 3B, and what parts will work - for dummies thread", it was great to find the info on this forum when I first decided to try a merkur turbo, it would be nice to take it up a notch and get some design info a compound setup now for those who like to fabricate and are attracted to compound turbo's, but find sizing and sourcing parts too overwhelming or intimidating to start such a project.

 

[gerg]

Ok, so this is a lot easier to write about since your goals are similar to mine.

The large turbo is the easier of the two on this since I run essentially your merkur turbo with a larger exhaust housing (.63). Mine is old and crappy and still puts out 10psi at 2000rpm. So you could swap your exhaust housing and get the same size for about 100$.

The smaller turbo I run is a te04h which has an older compressor design (13c) and a turbine which spools about 8 psi at 1500rpm. That was not my origional intention. I just happened to have this turbo in the shop and thought it was small enough. I can screw with my external wastegate a bit to get better 1500-2000rpm boost, but I cant do much before 1500 unless I run a turbo with a smaller turbine/housing.

I thought about running the WRX td04-13t-6cm mainlander ran on his truck as it works well through most of the rev range (up to 2800 with very good boost below 1500) and is easily had. I came accross a slightly smaller turbo which has the same turbine with slightly less trim and a 5 cm exhaust housing instead of 6cm and might combine the two turbos.

You can easily find the td04l turbo for under 150 bucks on ebay as guys swap them out for larger turbos so they have low kms and generally are in good shape.

A variable vane turbo for the small side would be great but I am still learning about how to control them and a nice one goes for about a grand landed in Canada in nice shape.

So in short I would recommend:
.63 housing for your merkur (large turbo)
Buy a td04l-13t-6cm wrx sti mitsu turbo as your small turbo.
Get a seriously large wastegate such as a 60mm one which are pretty cheap these days (under 150$).

Welding the manifold is another topic as there are several ways you could do it. In the case of your hilux engine bay, making it fit would take priority.

 

[gerg]

Now if you want to get into how I sized the larger turbo, that was somewhat complicated as I had to teach myself and I intentionally left out one large variable. I can say for sure the larger tubo (t3-60trim) can feed the smaller one (13t) air (12psi) up to about 2900rpm if the smaller turbo runs less than 15psi which mine is wastegated to 10 at the moment. I have not really been able to figure out how, as the large turbo outlet temps rise, it changes intake charge air density for the smaller turbo and the maps go completely weird with high intake temps. So in short I just kind of ignore that fact as it interferes with my hypothesis. Last time I checked my outlet temps they were around 310F for 24psi or something like that which runs in the high 70s for efficiency. I haven't measured my back-pressure yet.

Maybe you can answer that Dougal? As intake temps rise, it pushes everything over to the left. It make me want to use compressors that would normally map way too small for the engine, but with high intake temps they land on the island really well. WTF is up with that? Its so annoying.

 

[Dougal]

IMO the main difference between a compound set for maximum boost and a compound set for maximum range is the wastegate setting and some tweaks of turbo size.

Gerg, I see root(tref/tLt) as a correction factor on some maps. Since compressor maps are done on a mass-flow basis, this would shrink the map down and to the left. Similar to what altitude does.
The square root of 400/293 means even when fed boost at 107C it's only a modifying factor of 1.16.

 

[cody c]

Ok, so this is a lot easier to write about since your goals are similar to mine.

The large turbo is the easier of the two on this since I run essentially your merkur turbo with a larger exhaust housing (.63). Mine is old and crappy and still puts out 10psi at 2000rpm. So you could swap your exhaust housing and get the same size for about 100$.

The smaller turbo I run is a te04h which has an older compressor design (13c) and a turbine which spools about 8 psi at 1500rpm. That was not my origional intention. I just happened to have this turbo in the shop and thought it was small enough. I can screw with my external wastegate a bit to get better 1500-2000rpm boost, but I cant do much before 1500 unless I run a turbo with a smaller turbine/housing.

I thought about running the WRX td04-13t-6cm mainlander ran on his truck as it works well through most of the rev range (up to 2800 with very good boost below 1500) and is easily had. I came accross a slightly smaller turbo which has the same turbine with slightly less trim and a 5 cm exhaust housing instead of 6cm and might combine the two turbos.

You can easily find the td04l turbo for under 150 bucks on ebay as guys swap them out for larger turbos so they have low kms and generally are in good shape.

A variable vane turbo for the small side would be great but I am still learning about how to control them and a nice one goes for about a grand landed in Canada in nice shape.

So in short I would recommend:
.63 housing for your merkur (large turbo)
Buy a td04l-13t-6cm wrx sti mitsu turbo as your small turbo.
Get a seriously large wastegate such as a 60mm one which are pretty cheap these days (under 150$).

Welding the manifold is another topic as there are several ways you could do it. In the case of your hilux engine bay, making it fit would take priority.

Perfect. Youve pretty much identified the two or four parts needed. Now I will have to get the motor in the engine compartment to see how much room I have, that will be a little ways down the road though.

 

[gerg]

Here is how i was going to fab up my next manifold. It has several bennifits:

easier to weld up
can utilize divided manifold on large turbo making it more effecient and spool faster
turbos can be changed out easily for different ones (less welding)

Drawbacks:
will add turbo lagg on small turbo during normal accelleration. during towing or really slow accellerations the small turbo will still spool at low rpms. Its boost will just be delayed.

Because the flex pipes are downstream of both of the turbos the fabing is much much easier and dosent have to be as exact. I would recomend this way (in the pic). I did it with the small turbo first and getting it to fit properly was very tedious. I 'll draw a pic later for you on how mine is currently.

 

[cody c]

I was thinking small turbo first. Is there any cons to the small turbo closest to the manifold as opposed to the larger one closest?

 

[Tapage]

I always wonder seen this kind of setup if the small turbo won't be over spin at higher rpm's by the bigger turbo ..

 

[cody c]

I always wonder seen this kind of setup if the small turbo won't be over spin at higher rpm's by the bigger turbo ..

I think the 60mm wastegate is reccomended to bypass the smaller turbo to prevent damage to it from overspooling. Speaking of which, what pressure range should one use for the wastgate? 14-18psi, 20-24 psi etc?