93toyota4x4

Ok, that makes sense. I figured it had something to do with heat.

MudHippy

Many reasons. But mainly because:

• The root cause behind why the #6 cylinder runs so hot on this engine is the crossover dumping the exhaust from cylinders 1, 3, & 5 right in the general vacinity of the #6 exhaust port. Which is already having the exhaust from cylinders 2 & 4 dumped onto it too. Thus, a hot spot is created on the engine there. This results in excessive thermal stresses and accelerated wear on engine parts located in or around that area. Namely the #6 cylinder and/or everything to do with it. I also suspect that it's the cause of the other, less popular, hot spot, the #1 cylinder(which is where/why my HG blew). The reasoning there being that it's presence is enough to cause heat to build up at the #1 exhaust port. This, I suspect, is occuring due to the crossover being too restrictive. So, anyhow, eliminating the crossover eliminates the hot spot(s). And with less of the associated wear and tear taking it's toll, all is well in 3VZ-Eland.
  
• The crossover is restrictive in comparison to an open/straight pipe.
  
• It's the only way to run a true dual exhaust. Which is always a good thing performance wise.
  
• It makes removing the heads easier.

What else am I forgetting to mention?

dubbsbetty

iTrader: (2)

Uhh............ It sounds good

grinner

Saying hello as a newbie and bumping an old thread. I am on the fence about the crossover elimination. Is there any heat issues with the exhaust coming so close to the fuel and brake lines, clutch slave cylinder, starter wire, and floorboard. I just put the motor back in my son's 94 4x4 pu and left off the crossover pipe to do this mod. I am really worried about creating a death trap. Thanks for the replies. For the record, I have a 95 4x4 pu with the 3.0 and have 295,000 and have never had to do hg repair, but I know it won't be long. The 94 was bought with a burnt valve with 260,000 miles. My reasoning is if both trucks lasted that many miles, I think another 250,000 miles would not be possible.

pplusent

I just did a crossover mod, but ran it just past the trany and moved the O2 sensor just past where I came in with a Y junction. flanged it so the whole cross section can be removed for trany work and used the cross over heat shielding to keep fuel and brake lines cool. total cost right around $100.
I have read the other mods on this sight and wanted to mention that big is not better, keep your pipes 2" OD or under up to where you Y in or at least the first 4 feet. In fact you should stay as close to 1 3/4 as possible! there is a reason the factory had a 1 3/4 outlet on the manifold. Kept mine at 1 7/8" to the Y. Hard to find shops to bend 1 7/8 though.
Larger diameter pipes (over 2") will destroy your low end torque.
I have been on a lot of pit crews and the rule of thumb is small dia tube headers for our off road stuff (low end torque low speed) and big tubes on our pro stock where we run 8 to 10000 RPM 1250 hp at 212 mph all the time.
Your mod looks great, just watch out for the rocks.