Can a 6 lb. beef tenderloin be grilled and not roasted?

We have done this. It's excellent. Look at Seriouseats.com for very good instructions.

The best way to do this on the grill is the reverse sear. Cook the meat over low indirect flame until the internal temperature reaches 105-110 deg. F, remove the meat, tent with aluminum foil and rest while you crank up the fire.

Then sear the meat over the flame until the internal temperature reaches your desired degree of doneness, for me 130 deg. F which is medium rare. The advantage to this is more even cooking and a crispier crust.

An alternate method is to start the meat in a slow oven, like 250 deg. F and again take the meat to 105-110 deg. F, then finish on the grill as noted above. This is the method I generally do my beef and pork roasts (start in oven, reverse sear on grill to finish).

This is kind of a rip on sous vide roasting (start low and slow).

Hi Sheri, I grill it whole all the time. Salt & pepper it up and get a nice crust on it. Someone showed me a good technique which worked well. Grill it half way through 60-70 degrees internal. Take it off , rest it for 15 minutes then put it back on to finish cooking. This gives the inside time to catch up to the outside temp. let it rest before slicing. Good luck, cooking the whole tenderloin is much better than the individual fillets, at least for me. remember ends will be more done then middle so watch carefully. better under than overcook the meat.

Here's one option for grilling your tenderloin: https://food52.com/blog/4178-steven-raichlen-s-salt-crusted-beef-tenderloin-grilled-in-cloth-lomo-al-trapo I know yours is larger than the recipe calls for, but there are comments from folks on the recipe who successfully followed the technique with larger pieces.