If you want more confidence in getting good results, you guys should run some calcs to see how well the turbos match the engine before attempting such a project. Recommend purchasing the book "turbochargers" by hugh mackinnes, where he actually walks through running the calcs for a 2-stage sequential turbocharger sizing process. It is neither intuitive nor simple but I think it is important if you want to achieve good results.
Spike: simple question, but complicated answer. 1.6lTD Garrett, according to dyno runs done in my car with a short exhaust system (which didn't help low end torque) in 4th gear, show torque peaking (and thus I believe, peak 10psi boost being hit) at 3500 rpm, while some G-tech testing I've done at other points in time (without various other modifications been done to the car) with testing being done in 3rd gear on a flat road show torque peaking at 2800-3250 rpm (depending on the modifications.) Some modifications that appear to change this rpm point are: governor/fuel quantity setting, injectors (1.6lTD or 1.9lTD 2-stage), exhaust tract length (full length exhaust seems to beef up the power curve and gets the turbo kicking in at a lower RPM vs a short exhaust that terminates before the fuel tank, etc.) Heat wrap and ceramic coating on exhaust manifold (both of which help get more energy going through the turbine wheel), etc.
I would also expect it to depend on how quickly the car accelerates, IE: a light weight car with low-rotational inertia wheels and light flywheel and in a low gear will accelerate very quickly, possibly reaching redline before the turbo barely even kicked in at all, vs say a heavy vehicle going wide open throttle in a high gear.
One way that might be good to eliminate the vehicle weight/turbo lag from the measurement is to test while loaded at a constant RPM, and determine if peak boost can be reached or not. I can say that a stock 1.6lTD w/ Garrett will not be able to make peak boost loaded at steady-state 2000rpm (and might need 2500rpm steady-state wide open loading to develop peak boost), but mine with the mods will make peak 10psi boost at steady-state 2000rpm! (Now it takes a few (like 3) seconds at WOT to get to peak boost at 2000 rpm, but it does get there!
Where before when it was stock and I did the same test, IIRC, it got to maybe 2 psi at peak loading at a constant 2000rpm even when I waited a long time like 10 secconds.
Topic: 1.6TD w/ stock Garrett turbo lag? (Read 6731 times)
