Alright so my brother has this 87 Bronco II with a 2.9L and 5 speed. The end of the tail pipe that connected to the muffler rusted soo he took the muffler off and had a cherry bomb welded directly onto the cat. then a 90' elbow and a chrome tip welded after the cherry bomb to get the exhaust out right before the rear tire. Now it has a strange backfire sound after u rev it up and then let off. My dad said it is because of the 90' elbow. And it wouldnt do that if it wasnt an elbow right after it? Is this correct and how do you all think the 2.9s sound with a glasspack on them?

 

Not as good as with two glasspacks on them...or better yet, two Flowmasters.

As for the strange backfire sound, it sounds like the wrapping sound that is inherent with glasspacks, I don't think the 90º has anything to do with it. If you were to convert to dual exhast with two glasspacks and a crossover, I think you'd get rid of that sound.

 

he does plan to convert to dual exhaust but...it has 2 cats on it but on one side...if he isnt worried about emissions can they be removed? or are they actually vital to the performance of the engine? I know there are a few companies that carry headers. How well do these improve performance?

 

That engine doesn't use air injection so EFI performance won't be markedly affected by their removal, however, it's against Federal law to remove them even if the vehicle isn't in a state where it's subject to inspection. Personally, I'd install the headers followed by new high-flow cats (one on each side) and then go on back from there with duals. I'd install a crossover as well.

Don't size the pipe too large or low RPM torque will suffer. 2" pipe should be plenty for duals.

 

What about 2-1/4"s? and an X-pipe

 

X-pipe is fine, it's a better form of a crossover. I think that 2-1/4" pipe would be a bit much for a 2.9 though. It would sound nice, but as I said, you'd lose some bottom end.

 

Right. Im sure hes not that worried about the bottem end though cuz he doesnt do any offroading or anything like that...yet

 

Maybe not, but it can be a bit sluggish on the acceleration in normal street driving and that can be a bit of a pain.

 

Well what else can be done...other than head work? Are there any parts to improve intake like a cold air intake or does he need to make his own from the stuff they sell at autozone?

 

the uhm silicone tubes and fittings and the clamp on filters

 

He already has the bigger throttle body (later ones were smaller) and really, there's not much bolt-on stuff for these engines. To really get some power out of it would mean opening it up and changing the cam, porting the heads and other typical hi-po tricks.

Some later 2.9s (in Calif. anyway) had Mass Air but there wouldn't be much use in converting to that without making some major changes inside the motor that would necessitate the change. And if going to all that work and expense, it's easier to just swap in a 4.0.

But the cold air intake might help a bit. For sure, I'd just make my own.

 

Yeh, he said if it was a S-10 Blazer he would put a 4.3 in it...so i think im gonna try and get him to go for a 4.0...but what manual tranny is compatible with that?

 

The M5R1 5-speed as installed in later Rangers is the best one out there for these engines. The 4.0 shares the same bolt pattern with the 2.9. so the tranny you have now will bolt right up but probably isn't as strong as an M5R1.

 

Alright, Thanks for all your help.