Tri-y header length in a 4cyl toyota pickup?

[SOHCman]

Stock my pickup has very long tri-y headers (4 cyl engine, 22R) and is carbed. I am swapping a full exhaust from a 93 fuel injected pickup, and the manifolds are the same, but the third "Y" meets only a few inches from the bottom of the manifold. Comparatively the stock Y must run about 2 ft before the Y meets back under the cab.

My question is, should I expect a different torque curve? I know tri-Y headers are meant for torque (thats right, torque from a 4 banger) but I thought perhaps the length might change backpressure/velocity?

Thanks!

 

[dparm]

Yes, the length of the tubes will change the torque curve position.

 

[meep]

i thought 3Y headers were for higher rpm flow, and the 4-1 headers were for torque???

 

[punisher]

Depends on the individual setup. Generally 3Y make more low end (assuming the headers are configured properly) as you get better scavenge at lower RPMs with a bit less restriction at mid RPM ranges. Gotta remember, a 22R in stock form is a tractor engine with that 3.5" stroke.

I have run both on a 22R (carbed 1981) and never noticed a real difference between stock and individual tubed headers (Downey small tube). The 22R has breathing problems on the intake side, so unless there is some problem like a clogged cat/mashed exhaust pipe etc, you don't get a real butt dyno improvement doing exhaust work IMHO. I eventually ended up with a downdraft Weber and an Isky cam on it and can honestly say, the cam woke it up more than anything. Those that still deal with 22Rs, and want power out of them, go to a 20R head and better pistons.

 

[SOHCman]

Thanks for the replies,

I am not really going for power or anything, just replacing an exhaust that has given up the ghost. The 22R definitely IS a tractor engine punisher! I don't want to give up any torque (low end torque) and wanted to make sure the shorter tubes won't move me in the wrong direction, or require adjustment of the carb.

When I first got the truck the PO had ran the exhaust into a cherrybomb and out in front of the driver rear wheel. It was absolutely GUTLESS with so little back pressure. I put a "real" exhaust on with cheap parts and it was much improved, but they are all rusting out. (lesson learned)

 

[mechtech2]

There will be a minor change.
Who knows if it will be better or worse?
All bench racing talk about 4 into 1, tri Y , etc., headers becomes muddy when you put an exhaust pipe in back of them.
The supposed benefits of any type is totally changed with a pipe, cat, and muffler in the system.

 

[SOHCman]

Originally Posted By: mechtech2
There will be a minor change.
Who knows if it will be better or worse?
All bench racing talk about 4 into 1, tri Y , etc., headers becomes muddy when you put an exhaust pipe in back of them.
The supposed benefits of any type is totally changed with a pipe, cat, and muffler in the system.


Gotcha... My used replacement exhaust IS a full Toyota pipe-cat-muffler-tailpipe, so hopefully it is at least more efficient and quieter than the "sound master" and generic parts I had.

Currently I am fighting one remaining manifold nut with a propane torch and PB blaster, I'll post my milage and butt dyno findings once it's changed out.

 

[Cujet]

Actually, tri-y's are not true tuned headers and are much less "picky" with regard to pipe length, size and so on. I suspect you won't be able to tell the difference between the two.

 

[meep]

I am personally a big fan of headers - there are more gains to be made there than any other part of the exh system. either 4-1 or 3Y would add some spunk-- and then going towards the intake manifold next.

Heck- a dremel with some grinding stones might be able to open and smooth out the intake some without any more $ than the stones themselves. IIRC it's a 1bbl carb too, right?

 

[SOHCman]

Originally Posted By: meep
I am personally a big fan of headers - there are more gains to be made there than any other part of the exh system. either 4-1 or 3Y would add some spunk-- and then going towards the intake manifold next.

Heck- a dremel with some grinding stones might be able to open and smooth out the intake some without any more $ than the stones themselves. IIRC it's a 1bbl carb too, right?


Actually it's a 2bbl, with the secondary opening at roughly 70% throttle.

For an update, I have the new exhaust completely installed now from pre-cat back. Ends up the short try-y before the cat interferes with the torsion bar. A 4wd frame must have some small change to the angle of the bar not obvious to my eyes. So the original long tube Y was used all the way to right before the cat.

On first start the exhaust released a ton of stinky steam from water that must have been trapped in the system. I think it sounds great, a nice quiet idle and zero resonance at any engine speed. The butt dyno seems to show improved grunt, I'm hardly on the throttle at highway speeds. Now to measure the mpg...

 

[SOHCman]

Well, after a few tank fulls now, I seem to be averaging about 24mpg with mixed driving. I neeed to do a road trip and find out my straight highway milage. My commute ranges from 70 to 80 mph most of the time to keep up with traffic, so I'm sure going the posted speed would help as well.

 

[mechtech2]

Discount initial MPG, as you are probably playing with the power!

 

[SOHCman]

Originally Posted By: mechtech2
Discount initial MPG, as you are probably playing with the power!


"Power!" Yes, I wish!! I think I'm going to rebuild the carb and do a tune up/valve adjustment to see how high I can get it. Maybe even low rolling resistance tires?? No, not really on the tires...

 

[SOHCman]

Just hit 25.99 mpg on a fill up including CRC gtp, now to take the topper off and get new (and balanced!) tires and see what that does.