DSM T25 on a 2.2L S10
 

I am in the process of picking up parts to install a DSM T25 on my '00 S10 2.2L. I have the turbo, 1st gen DSM BOV, all flanges needed for the header and exhaust, oil drain flange, etc etc.

So I have answered most of my questions through endless searching all over the web including here. I am set with how to feed and drain oil for the turbo, coolant is handled. Fuel for the motor is handled with a new pump and injectors. But, a few that I have yet to find an answer to I hope you guys may lend some guidance?

What would be a good size for the cold side piping? Outlet of the compressor of the turbo is 1 11/16". Would 2.25" be too big and loose boost pressure?

What would be a good size exhaust to run off of it, the turbine side? Outlet of the turbine side is 2 1/8". Would a single 3" be too big?

Plan for the header is 1.5" primaries into a 2.25" collector. I plan to make this flanged before the main turbine flange so later down the road a swap to a different turbo would just be a matter of making a new adapter from header collector to turbine inlet. Same for the outlet with a flanged dump pipe.

cold side depend on how much u plan to push. 5 to 8 psi meh 3 inch is to much. stick to 2 to 2.25 on the cold side for stock motors.

down pipes can help in many ways. a smaller one will help on boost drop between shifts or keep it in boost better. but on a t25 you have no prob with spool so the bigger the better. course this is my opinion. good luck and post pics.

ive built a 98 s10 2.2 turbo so ask me anything.

2.5" charge piping is the norm.
you will need silicon reducers to adapt the 2.5 charge pipes to the turbo compressor and throttle body. go to silicon intakes. com to order them. there the cheapest around.

go with 2.5" exhaust. any more is a waste of money unless your goal is big hp numbers.

1.5 primaries is a must since the exhaust header flange requires 1.5" primaries
as far as the collector outlet purchase one that has a cone shape or reducing collector so you can cut off the collector outlet to the size you need.

5G_4G15...

Plan for now is 8 max since the motor has 246K. After a rebuild with a ported head and some studs I want to see what the max boost of 15 or so with this T25 can get me....

busa4...

I knew you would chime in! And glad you did. I was looking into 2.25" pipes. I want it all low rpm boost as this is my commuter. Need that low end to get moving.

Plan it to use a Flowmaster type reducer as they are smooth flowing.

2.25 - 2.5" pipe will be fine. this small difference wont be noticable. 2.5" is the most common size so there are many parts available when using 2.5" exhaust and boost piping. what controls lag is the size of the exhaust housing.
i used a t3/t4 hybrid turbo on my build and it spooled up at 2500 rpm. your t25 will spool quicker.

Excellent info guys, thank you.

So cold side I will set up with 2.5" piping and intercooler.

Hot side I want to run the 1.5" primaries like already stated (and the flange requires it anyway), into a 3" collector. Then from the main collector I will make an adapter from the 3" and reduce it down to the 2.25" for the T25 flange. I can them make any collector "adapter" if ever I want to change to a different turbo.

Outlet I will set up with 2.5" and a nice flowing muffler.

If it spools anywhere under 3000 I will be very happy. The truck lives at 2700 on the commute so it should make for a fun little truck.

What do you guys think about this intercooler?

Now as far as it would be installed on my truck the most psi it would ever see is 15 with the T25 and probably 250-260 crank hp. I have a template of the size cut out and plan to yank the grille in the next few days and see if it will even fit. I want to keep all charge pipes on the driver side of the engine bay to keep them as short as possible and I think it will make for a cleaner install. Routing it to eh passenger side and then into the TB makes for a few sharp bends that I am not happy about.

UNIVERSAL 16.5"x11"x2.5" TOP MOUNT/EXIT JDM INTERCOOLER - eBay (item 140450674975 end time Feb-04-11 19:30:56 PST)

16.5'' x 11'' x 2.75" High Flow Intercooler

Square High Flow Tube & Fin Design

All TIG Welded 6061 Aluminum.

PSi Drop under 0.2. Other Intercooler usually drop 2 Psi Some are More.

Inlet/Outlets are offset on both sides of the intercooler

Core Size: 11" x 11" x2.75 with 2.5" inlet/outlets

Max PSI is 40 Up to 600HP

its going to be very difficult to route the inlet and outlet on the same side. most intercooler installs ive seen on these trucks required a good amount of cutting to the radiator support to sneak the pipe behind the headlights. as far as too many bends dont worry about it. the mandrel bent tubing will be more than adequate to allow the air to flow smoothly even on the tightest of bends. unfortunitely there is no other way around it. you are going to have tight bends. my car has nine 90 degree bends and two 45 degree bends.

I have the same turbo on my Honda I am running 2.5" pipe with a DSM side mount. I was only runnin 10psi. I might not be thinkin correctly but I believe that turbo looses efficiency at like 14psi. After that its just blowin hot air.

Thanks for sharing. Wasn't really thinking of how the pipes will pass behind the headlights. Point taken! Still in the planning phase there so I will cover all options. May be best to get some 2.5" exhaust pipe and see how and where they will best fit and then decide what in/out intercooler setup will accommodate that the easiest.

I did find one build where the person used the dsm intercooler and mounted it behind the rad support (right behind the DS headlight) in the engine bay. This is what got me on track of the piping how I asked. Just figured the engine bay was not the best spot for it.

You are probably right. I have heard this, 10psi is about as good as it gets. I only said 15 as I have been told this would be a very max psi I could push with it so kinda mentioned it to see if the intercooler I linked would be ok at that pressure.

Oh ok. Most intercoolers you find even the ebay ones usually 30 with no prob. Dont get to big of one cause of pressure drop.

Ok guys I have a few more if you have the time. Been searching and reading enough to make me dizzy. Didn't find any real answers to these again....

Where is the best place to install the BOV (1G dsm)? Before or after the intercooler? I also have heard as close to TB as possible but how close... 6", 12", etc? Does it get mounted 90 degrees to charge pipe or at a specific angle?

On the wastegate side of things... how far away from the turbine outlet do I reintroduce the wastegate "waste" into the main exhaust? And from what I have read this one should enter at a 45 degree angle for best results?

On a side note I have the fuel pump and injectors in hand today thanks to UPS.;D

90* is fine, and anywhere in the intercooler pipe will work for the bov. The difference, if any, will be negligible. The 1g bov will have no problem venting whatever volume the t25 can throw at it.

I would just try to find a DSM "o2 housing." Plenty of people have made plenty of power on the stock casting and it will re-join the wastegate flow fairly well. 1g and 2g are the same internal casting besides the o2 sensor placement. Tubular ones are cheap, too, although again the stock casting has worked fine especially after some cleaning/matching at the outlet.

The only issue I have seen when I looked into using a stock dsm o2 housing is they make a fairly sharp 90 bend shortly after the outlet flange. With how I am placing the turbo in my truck I need it to be a straight outlet. It won't make any bends till a good 12" (at least) after the outlet and even then a 90 would run the exhaust right into the frame rail.

But you did bring up another question I forgot about… the o2. How far back from the outlet should I place it?

bov position doesnt matter as long as you dont have a maf sensor which you dont. just make sure you hook up the bov vacuum signal to an intake manifold source. my current vehicle has the bov mounted on the charge pipe about 1.5 feet after my turbo. ive seen some people mount them on the charge pipes going into the intercooler or on the intercooler itself to project the most noise.

you want the o2 sensor as close to the outlet as possible. the farther away from the turbo you get the more inaccurate it will be. as far as your down pipe. it will have to all be custom made. purchase a turbo downpipe flange and start building the downpipe you need.

make sure the wastegate dump pipe enters the downpipe at least 6-8" away from the turbo as it will cause a turbulant restriction in exhaust flow.

90 degree bends will work as a transition but the smaller the bend degree, the better the exhaust flow. with low boost this makes no difference so using 90 degree pipe transitions will be the easiest way to go.

Excellent info guys, thank you!

BOV I plan to recirculate, I want it as quiet as possible. Rather people not even know it has a turbo. But on location, notes have been taken.

I do have an outlet flange I plan to use to build a custom downpipe for the reasons I already mention. But as far as bringing in the wastegate gasses in, again notes taken. o2 sensor I can put anywhere I want so I will make it as close to the outlet as I can.

All information is stored for when the actual build begins. Thank you guys greatly for all ideas & experiences shared, it is appreciated.

busa4... do you have any pics of the s10 you built?

i know longer have pics. it was lost on my old computer when the hard drive crashed. i built that back in 06 i think.

Ok guys. Are you sick of me yet?

Last one for awhile till I get rollin' on the actual build. I think I have every base covered by now. Sitting there last night clocking the turbo for my install and I have 2 vacuum nipples on the turbo… where do I connect these on a NA motor?

Wastegate nipple connects to…

Compressor housing nipple connects to...

I did a lot of searching but only find stock or modified dsm routing with a wastegate solenoid which I obviously won't be running.

No manual boost controller either as I won't be going over the 8psi the wastegate is set at factory.

Nevermind. Upon one last search I found my answer,,, they connect to one another.

are you using the internal wastegate? i thought you were using an external wastegate. cap off the nipple on the compressor housing. run a vacuum/boost line from the intake manifold to the turbo wastegate actuator. this will help prevent boost creep.

With the T25 I am planning to stay with the internal wastegate.

no problem. i was confused. internal wastegate makes the build a little easier. make sure you cap off the compressor housing boost nipple and run a vacuum/boost line from the intake manifold to the wastegate. the wastegate will open quicker preventing boost creep. the pistons in these motors are not very forgiving to lean or over boost conditions so preventing the boost creep will help save it.

Ok. So now with this known... can I T off the same vacuum line I am going to use for the BOV to also connect to the WG?

Busa4, how will that prevent boost creep?

yes. my current setup is doing it this way.

boost builds up from the throttle body and travels down to the turbo housing. if you use a boost reference at the compressor housing there will be a slight psi difference at the intake compared to the compressor housing. since your boost reference is at the compressor housing your wastegate will see 8psi boost but your intake will see 9 or 10 psi(this is just an example not exact numbers). this is known as boost creep. boost creep will always be there but you can try to minimze it. if you move your wastegate boost reference line to the intake manifold then the wastegate will open earleir minimizing boost creep since there is a psi difference from the intake to the turbo compressor housing.

Cool... thanks busa!

Ah, difference in vocabulary terms. Boost creep is commonly referred to as the wastegate not being able to bypass enough exhaust gas around the turbine and control boost in higher rpms, causing boost to rise with uncontrollably with rpm.

There will be a slight difference(from pressure drop after the intercooler and piping) between the compressor outlet(more psi) and throttle body(less psi). It's a little backwards from what you're describing :p but same concept.

If you have a problem with boost spike(overshooting your target value then immediately settling down), keeping the wastegate source/reference as close to the compressor outlet and with as short of a line as possible is your best bet to combat it. The difference in psi(usually 1-2psi) from running between the two sources can be accounted for by using/adjusting your MBC.

I won't be running a MBC as I have no plans to push more boost than the factory wastegate is set for.....

[QUOTE=Mr Peepers;1304940]Ah, difference in vocabulary terms. Boost creep is commonly referred to as the wastegate not being able to bypass enough exhaust gas around the turbine and control boost in higher rpms, causing boost to rise with uncontrollably with rpm.

There will be a slight difference(from pressure drop after the intercooler and piping) between the compressor outlet(more psi) and throttle body(less psi). It's a little backwards from what you're describing :p but same concept.QUOTE]


its not backwards. best wastegate control is from a boost reference signal coming from the intake manifold. boost pressure builds up from intake and travels toward the compressor housing so if you use a boost source at the compressor housing your actually boosting more at the intake manifold than at the compressor housing. your boost gauge will spike above your targeted boost range until the wastegate opens. it is a delay from the time the intake see 8 psi to the time your compressor housing sees 8psi. a smaller than needed wastegate can cause an over boost condition and not really a boost spike.

Sorry to stray off topic for something somewhat trivial but very basic for understanding turbo systems:

"With Mass Flow and Manifold Pressure, we are nearly ready to plot the data on the compressor map. The next step is to determine how much pressure loss exists between the compressor and the manifold. The best way to do this is to measure the pressure drop with a data acquisition system, but many times that is not practical.

Depending upon flow rate, charge air cooler characteristics, piping size, number/quality of the bends, throttle body restriction, etc., the plumbing pressure drop can be estimated. This can be 1 psi or less for a very well designed system. On certain restrictive OEM setups, especially those that have now higher-than-stock airflow levels, the pressure drop can be 4 psi or greater.

For our examples we will assume that there is a 2 psi loss. So to determine the Compressor Discharge Pressure (P2c), 2 psi will be added to the manifold pressure calculated above."

Quoted from:
TurboByGarrett.com - Turbo Tech103

^Compressor discharge pressure will always be higher than intake manifold pressure because of pressure losses in the piping leading to the plenum, especially through an intercooler.

The real issue here though is pointing out that the compressor outlet will see a change in pressure before a change is seen at the intake manifold; making the boost reference off the compressor outlet/discharge more responsive to changes in boost and help control any spikes that could occur from the wastegate signal being delayed.

"Best" is relative. If you want to run "x" psi(measured at the intake manifold) regardless of pressure loss across the intercooler etc, a boost reference off the intake plenum will do that. If you want the wastegate to respond quickly to any changes in boost, the shortest path/distance from the compressor outlet to the wastegate will do that.

this is a very true comment but it doesnt reflect how the boost travels. pressure drop and boost spike are two very different things. a well built intercooled system should only drop boost pressure by .5 psi or less. the pressure drop and boost spike will always be there but the boost spike can be minimized. im talking about the small period of time it takes for the boost to travel from the intake to the compressor housing causing a spike in boost pressure due to delayed wastegate opening. this issue usually only comes up when the engine is at a high load. a wastegate boost reference at the intake manifold is more accurate. ive been doing it this way for many years and many builds and never had a boost spike issue.

Agree to disagree :)

i guess so..... :)

Hey busa.. you still around?

If so, what did you do for fuel pressure regulator on your build?

I have a racetronix pump that can support the power and 63lb injectors. But they state I need to have a rising rate regulator? Is my OE one rising rate?