New guy looking for Compound turbo information

[Saab900]

Hey guys! I will be straight up and say I am not a DSM'er, never owned a Mitsubishi but I always loved the second gen eclipses! I am an avid Saab enthusiast. I got an account on here because I have found more information on compound turbo charging on this site than anywhere else, I had hoped to post on this thread because it is exactly what I had in mind.

I read through that thread, and it made me realize I needed to find out why exactly I wanted to build a compound turbo system, aside from being different and 2 turbo's being awesome there is one very important reasoning for a compound turbo system, the smooth torque curve, its the spike of the turbo system that is the Achilles of the Classic Saab 900 and I really want to take full advantage of the great engine Saab made without worry about having a stock pile of transmissions. The end goal will not be a race car, just a fun daily/weekend car with something noone else has done before.

Our engines love HX 35's but if I could pair it with a smaller turbo for more power and a better torque curve I am in. I just need more information on what the best bet for the smaller turbo would be.

Thanks guys!
Alex

 

[LandSpeed-DSM]

How much air are you looking to move? Where would you like to make the bulk of your power?

What displacement? What fuel?

We're going to need more specifics in order to help.

 

[Saab900]

How much air are you looking to move? Where would you like to make the bulk of your power?

What displacement? What fuel?

We're going to need more specifics in order to help.

Not 100% on details, im planning on learning more about the specifics of turbo's, I guess I left out all the details though, I will most likely be building it on a 1990 Saab 900 with a 2L 4 Cylinder engine that is factory turbocharged with a T3 turbo (not 100% if my car has the Mitsubishi trim turbo or the other one) The bulk of the power I would like fairly spread across the rpm range, but I would like a quick spool, these cars spool with the t3 fairly early (don't quote me, havent driven the car in a while but 2500ish is boosting, not full but most the way there) so I guess 2-2500 to 5-6000 RPM is where I want the power.

EDIT: And please excuse me if I mess up, I am used to much much less structured forums, although I have a feeling y'alls system makes for a very strong insightful community, I mean no disrespect, just new to me.

 

[LandSpeed-DSM]

Well thats a start I suppose. Now how much power are you looking to make? You are determined to use the HX35?

Is this an SOHC or DOHC B motor?

What is the stock turbo compressor/turbine size?

 

[Saab900]

Well thats a start I suppose. Now how much power are you looking to make? You are determined to use the HX35?

Is this an SOHC or DOHC B motor?

What is the stock turbo compressor/turbine size?

Ill get more specifics tomorrow but it is a 16valve DOHC B202 (if that means anything to y'all) not determined to use a HX35 but I know they are readily available and well sized as well as affordable, huge numbers are not the goal here, fun is, 500 would be awesome to brag about but probably unrealistic in a FWD car, 3-400 would be the target, oh and I have upgraded the engine management system to the Saab T5 engine management system, so ECU tuning is easily available (in car live tuning is also possible with some more wiring) From what I understand the internals of these motors are good for at least 300 without modification, and the B234 (engine in a Saab 9000) is good for 500 without internal work, my 9000 Aero daily has 302,000+ miles on it and I don't drive it nearly as nice as I should but it takes anything I throw at it from towing Integras out of ditches, to hauling motorcycles in the back.

EDIT: And to clarify I am not coming here to ask for a list so I can go buy this and throw it together tomorrow, I am simply planning for what I thought was only a dream that I am now determined to make a reality in the coming years.

 

[Potenze]

The b202 is DOHC, The only problem with building up these Saab motors is that all the performance parts that you can find are pretty expensive. 3-400hp is quite achievable. One thing i would do for sure before you set off to make more hp is remove the balance shaft chain, cause while when a balance shaft seizes in a dsm it doesn't do a whole lot. in these Saab's the chain will destroy the engine if something goes wrong.

 

[Saab900]

The b202 is DOHC, The only problem with building up these Saab motors is that all the performance parts that you can find are pretty expensive. 3-400hp is quite achievable. One thing i would do for sure before you set off to make more hp is remove the balance shaft chain, cause while when a balance shaft seizes in a dsm it doesn't do a whole lot. in these Saab's the chain will destroy the engine if something goes wrong.

You familiar with the Saab engines? And I have a buddy who has been running probably about 350ish daily for years now, and has built quite a few engines and even more Transmissions so he knows all the little ins and outs and Ill have him help me when I get a spare engine to rebuild!

And If I can make it for the same or less price than I can buy it for I build it, its just more fun that way!

 

[Aww_420]

Nice topic. Very interesting i was thinking about this not too long ago. I will be watching this

 

[Saab900]

Sorry, life has been a little crazy. I haven't been able to get exact spec on the turbo because I have been trying in vain to fix my girlfriends clutch..

I do not have specifics (turbine/compressor) but its the stock T3 from a matching 1989 Engine out of a convertible so I am assuming its the earlier T3 and not the TE-05 they installed in the later models and the SPG's.

 

[Mach1TaloN]

Nice topic. Very interesting i was thinking about this not too long ago. I will be watching this

Its all ready been done!
One of our moderators has had much success with his set up, and if your nice to him he could probably help ya out, or at least some pointers. Look for "99gst_racer"
Go have a look at his pictures, its amazing looking!

 

[GRAVEDIGGER]

You need to read through these two for sure. http://www.dsmtuners.com/forums/cus...compound-turbo-set-up.html?highlight=COMPOUND

http://www.dsmtuners.com/forums/dyno-talk/378908-compound-turbo-dyno-results.html?highlight=COMPOUND

Here are some others that might be or interest as well.
http://www.dsmtuners.com/forums/dsm...bo-setup-holset-style.html?highlight=COMPOUND

http://www.dsmtuners.com/forums/tur...turbo-exhaust-routing.html?highlight=COMPOUND

And these are for the wild side of compound turbocharging.
http://www.dsmtuners.com/forums/new...rging-compound-turbos.html?highlight=COMPOUND

http://www.dsmtuners.com/forums/cus...-turbocharged-non-dsm.html?highlight=COMPOUND

 

[Saab900]

You need to read through these two for sure. http://www.dsmtuners.com/forums/cus...compound-turbo-set-up.html?highlight=COMPOUND

http://www.dsmtuners.com/forums/dyno-talk/378908-compound-turbo-dyno-results.html?highlight=COMPOUND

Here are some others that might be or interest as well.
http://www.dsmtuners.com/forums/dsm...bo-setup-holset-style.html?highlight=COMPOUND

http://www.dsmtuners.com/forums/tur...turbo-exhaust-routing.html?highlight=COMPOUND

And these are for the wild side of compound turbocharging.
http://www.dsmtuners.com/forums/new...rging-compound-turbos.html?highlight=COMPOUND

http://www.dsmtuners.com/forums/cus...-turbocharged-non-dsm.html?highlight=COMPOUND

Thanks for the links! And I have read damn near every word in this thread and it is the main reason I am here. I made me realize this was actually a doable, achievable idea and not just the stuff of dreams!

Thanks for the other links though! I will definitely check them out!

Edit: So instead of doing anything I should be doing I've been reading through your links haha in the Compound turbo exhaust routing Caged mentioned using a Td05 (different than a te05?) with a hx40. Would a TD04 or a T25 match well to an HX35 or would I want to go smaller on the small turbo. My worry with a compound turbo setup using a small small turbo is I do not want it to choke the system, but ill be shifting between 5500-6500 rpm so I want that power coming in early and I guess 2-5000 rpms are where I would want the power in a perfect world.

 

[Saab900]

Sorry if double posts are not ok around here, but I was wondering if anybody had any more insight on this, I know most the compound turbo setups around here are going for big power numbers but I do not know enough about turbos to combine turbos, compare flow rates and such and so forth. Im learning but I learn better in practice and from others than I do by reading.

Edit: Kinda ridiculous question just popped into my head, but could you do a compound turbo setup with two of the same sized turbos (I know there are far easier ways to up boost but curiosity will be the death of me)

Also found this, I know its an over simplification but Im curious how accurate it is?
"A rule of thumb is the top turbo (small turbo) should put out in lbs/min roughly 50-60% of what the bottom turbo (big turbo) will be capable of."

Also as I am trying to wrap my head around this: you wastegate the smaller turbo, to avoid running the small turbo out of efficiency range, and in doing so helps the bigger turbo spool? At the point where the small turbo is waste-gated, the boost it pushes out will be entirely dependent on the air the larger turbo is pushing (since the smaller turbo will not spin any faster?) - am I at all on the right track with this (in an overly simplistic way?)

Thanks!
Alex

 

[Saab900]

So I am trying to wrap my head around how to set up the wastegates in a compound setup. Say I do externals before both turbos would I run the first directly off of vacuum with a xlb spring (x being the turbos peak efficiency range, then the second wastegate run off of my boost controller or with a stiffer spring set to desired max boost?

 

[Saab900]

Well I have decided to go against all of my sensibilities and everyones advice and I am going to try and build a mid range compound turbo setup. There is an HX35 on the way (that will be the big turbo) and I am going to use the stock T3 that came on my car. I am going to start collecting parts over the next couple months and keep reading everything I can read to better understand what I am going todo but I think the turbos should match up quite well, Ideally I wanted an HY35 but beggars cant be choosers. I am going to try running with the internal wastegate on the T3 just to get it running but long term want to do an external for the T3. I dont see any reason to run an external wastegate on the HX35.

This will not be a high caliber quality build like most of the builds that have inspired me, this is going to be a low budget hodge podge experiment done for all the wrong reasons, so let the fun begin!

Biggest thing I am unsureof at this point is how I am going to tun the oil feed and return line.. if I can just y the 2 lines together I should be golden but from what I've been reading thats a no no

 

[Saab900]

Long time, no update, she is built and has run and driven compound turbo'ed quite a few times. Finally got my hands on some Deka 630 injectors and a wally 255, just need to get a wide band and I can get her tuned and start actually pushing some boost!