Originally posted by 1fast2m4: To put it into perspective just type how to plumb in an external waste gate in fewer words than this "Crosover pipe in, Down pipe out" that's 6 words & a coma. I'll wait
It can be that simple if the quantity of procedural words is your chosen path to deciding on the best arrangement, but having built more turbo setups in a Fiero than I can recall, what I do know is that ease of access to other areas of the engine compartment for routine maintenance and repairs is important and the best and most accommodating place for an integral wastegate turbo is over the transmission where it would be in the way of tranny access as well as the source of increased heat in that area of the decklid potentially warping it.
My turbo is on the backside of my motor out of sight and my trunk is still in place and my transmission cables and other items accessible if needed for problem solving. If you have the tools to build your own exhaust system, internal vs external is pretty much irrelevant in favor of packaging which I propose is the main determinant. To each his own, they both have a benefit however, having switched from integral to external, I know I'm not giving up the added flexibility turbo options and size wise (try fitting my T4-T67 above the tranny) to go back to an integral wastegate when in addition to flexibility, literature favors external as the better arrangement.
Perhaps if you add the cons, the internal arrangement may not be so attractive. There's a lot more to consider than just crossover and downpipe, you still have to connect a good air filtering system and connect the turbo to the intake. I also have a cold air feed using the OE filter canister instead of a quick filter on the turbo sucking in engine bay heat, that's not easy to achieve with the crossover turbo mount.
OK I did not win the turbo so fate has told me to wait a little... I did buy a bellow for the crossover from summit racing and I will be making the crossover be easily adaptable for the turbo... That's the main reason I'm building a new one... I also bought lots of extra mandrel bent 1.5" tubing so once I have a turbo I have enough tubing to make everything I need. I'm still planning on the evo turbo, I will get it this summer once I finish the rest of the work I am doing on my car... I still need to buy a tank of argon and paint so I will see how much that all costs.
I am trying to select a good location for the heat exchange that will cool the coolant in the intercooler. I want to put it in the engine bay where the cat should be... Would it get sufficient air flow there? Also, is it necessary to have a reservoir or overflow type container for the intercooler? I'm not going to drag race so I won't use an ice box or anything like that
That is a good question, and one I was eluding too earlier.
Some have reported success (No numbers that I've seen) putting it up by the front of the cradle, I think where the stock exhaust pipe is.. some argue this is warm air due to the rad flow of air towards the rear.
With my turbo location, if I could find the right interface it wouldn't be too bad. I think an air to water is the best solution, but expensive and heavy. The water meth looks like the best choice but it's not always there, and is complex with a pump etc.
It would be nice if it failed to have a backup conservative tune which the ecm would switch to with a fail contact input, but I haven't found an easy way to do it.
Originally posted by zkhennings: Well I would do air to water for sure but would it get enough airflow to the heat exchanger in front of the cradle, I don't want more lines running to the front of the car
You'll defeat the purpose of the liquid to air intercooler if you mount the heat exchanger (for cooling the water) anywhere other than out front forward of the radiator where it can get the most air. The small hose diameter is what makes it so practical as opposed to trying to run air to air intercooler pipes front and back. Install it so that you get the best performance from it.
Originally posted by zkhennings: But how detrimental is that to air flow through the radiator?
No effect as far as heat transfer, the heat from the A/C condenser is hot enough to burn you before it's cooled down before reaching the evaporator and it sits right up against the radiator. The heat exchanger doesn't get anywhere near that. The highest temp I've measured is just over 120 deg and that lasts about 3 seconds before temps drop back down to near ambient as the 10 deg static temp above ambient while not in boost is just the efficiency barrier at play. Aside from that, ahead of the radiator is the traditional location for all intercooling units.
I can tell with 100% certainty that the front mounted heat exchanger with a rear mounted intercooler works as Joseph wrote above.
While I have no experience with an air/air intercooler, I can tell you that an oil cooler mounted in front of the cradle did no good. Even after mounting an air scoop on bottom and a fan on top. I was expecting maybe a little help with my oil temps but go nothing.
Originally posted by zkhennings: Honestly I was thinking #24
Also since the manifold is hooked up with a vacuum line to the fuel pressure regulator, and under vacuum it lowers fuel pressure, then I assume when making boost it raises the fuel pressure. At what point will like a walbro fuel pump say "no" to more pressure?
24 Lb/hr injectors is about as high as you should go. Whatever is sufficient for the 3.1L Turbo Grand Prix (~23 lb/hr) will be sufficient for your build simply because pound for pound of boost it makes more power than the 2.8L and you will be hard pressed to make the kind of power it did with the iron heads and Fiero intake. The fuel pressure regulator is a non issue and was only made a topic of discussion in the past for motors being boosted without proper tuning access while on the stock injectors. Think about it, the fuel pressure setting for production cars is standard across engine displacements with changes in injector size and tune to deliver additional fuel.
When you install injectors considerably larger than what is necessary closedloop engine operation becomes more difficult to tune so keep that in mind. You'll need a super turbo 2.8L build before you start to threaten the ability of the Walbro pump to deliver. The Turbo Grand Prix would be a better mark for you to consider for your upgrades because it is closer to your displacement than the 3.8L.
I've gone as high as 18 psi recently using a stock GM adjustable regulator set to 40 psi static pressure and still have an AFR reading in the low 11s to high 10s at that boost level adjusting fueling in the tune.
[This message has been edited by Joseph Upson (edited 07-05-2013).]