Hey guys, I recently switched from k16 billet turbos to a set of xr770 xona turbos. There is not a ton of info on here or with the tuners on how to set them up. I got lucky, as pwdrhound happened to buy the bigger version of these around the same time, so we've been able to bounce ideas off each other to figure out how to optimally set them up. The wastegates come with blue springs in them set up for 11.8psi opening pressure. What we found, is that with the n75 boost controller off, they spooled up way too fast and in my car hit a peak boost of 1.2bar. They operated like a light switch, which is harsh on the engine, and terrible to take to the track. We spoke to Tial and our tuners, (I work with Markski) who gave us a lot of information, but in the end we had to take a guess and go from there. We decided to try the green springs first, which crack at 6.2psi. I preloaded the springs to crack open at about 8.5psi. They fully open at about 14.5psi. With this spring, the gates open up much easier and allow you to roll on to the boost. If you hammer the throttle, they still spool up fast. Now the car can control the turbo. I'm sure John will chime in and add whatever I've forgotten here, but if you are looking to go this route, and want a turbo setup that boosts between 1 and 1.3 bar or so, start with the green spring in the wastegate. Its much easier to setup on a bench than on the car. Ask me how I know!

 

Do these have better top end flow than k16s?

 

I think so. However, I'm not sure how to substantiate this. I think the flow numbers are like 49lbs per minute, they have 68mm compressors or so I'm told. I think they spool up a little faster and flow a little better than the k16 billets.

 

These should be awesome track turbos. I'd be careful about flooring it below 3500 RPM, you'd twist those connecting rods up good.

 

Agreed

 

XR770

Good info, thanks.
I also ordered a set of these awhile back and unfortunately have not yet had the time to set them up. Likewise, I also could not find much info on these pertaining to our cars.
Please keep us updated on any future thoughts and testing.

 

Just so I follow what you are saying... Are these progressive rate springs so by extending the waste gate rod you are increasing the holding pressure above what the spring is rated for?

With the N75 unplugged does the wastegate just get a direct reference for manifold pressure?

 

I don't know if they are progressive rate springs. But adding a bit of preload will increase the pressure at which they start to open. I am not an expert... but I can explain what I see when I turn my wrench.

With the n75 turned off on the map (its still plugged in), it allows the full manifold pressure to reach the actuator.

 

I'm no expert either. Does the boost reference assist the spring in holding the WG shut or does it fight against the spring to push the WG open? If you disconnected the boost reference would the WG crack open at what the spring is rated for or would it stay shut and the WG would never open?

 

Great looking turbos. I’m interested in hearing your comparison between your current setup and this one!

 

If you unplug the line to the turbo, the wastegate stays closed and you will grenade the engine

 

 

Thanks for the link, makes sense. I have the same tial WGs on my 1668 turbos. I'm curious if a softer spring with a higher n75 duty cycle might help smooth out power delivery.

 

yes. that is exactly what it does...

 

I'm tempted to get some of these new quick spool turbos and give them hell, I have rods and head studs in my car. I bet it would go like a big block car.