I believe there are two categories when it comes to designing and selling a product for a vehicle.
The first one is finding a weak point such as an engineering deficit between what the end user wants out of their vehicle and what the manufacturer has provided from factory.
For example, a turbocharger on a 79 Series Toyota Landcruiser is only really good for a maximum of 20psi of boost with a tune. Therefore, the need arises for a higher performing replacement turbocharger that matches or improves boost response but provides headroom to push more boost, which allows the end user to chase after more power and torque, safely. There is a need, therefore it has been met.
The second one is making shit for the sake of making shit.
Where no genuine need has been met, but if you have something for sale, people tend to assume there must be a reason to ‘upgrade’.
Aftermarket ‘performance’ 1VD-FTV cross over pipes fall into the second category.
There are theories out there that in some way shape or form, a manifold’s flow is equal to the flow of an exhaust.
That bigger must mean better.
Even if that theory was proven true (and we ignore all physics surrounding exhaust velocity, exhaust pulse energy, and turbine drive pressure), there is THREE major issues which still hold up the success of these products that we see on a DAILY basis.
When I say often, I’m leaning closer to always (in my experience), but have to accept the potential that there’s a manufacturer out there who’s beaten the system.
Let’s establish some drawbacks.
- A bigger pipe slows down exhaust gas speed. Turbochargers rely on high velocity exhaust flow to spool quickly. This is even more important at low engine RPM.
- There will be a heat loss. Larger volumes mean more surface area, which can let exhaust gases cool before reaching the turbo. Cooler gas means there is a less energy to drive the turbine of the turbocharger.
- Uneven exhaust pulse energy. V8 engine’s particularly rely on a balance of exhaust pulses to drive turbocharger speed. By oversizing the cross over pipe, it can cause the pulses to bleed into each other instead of transferring energy cleanly. This can hurt turbocharger spool. This is actually the most recognised ‘difference’ these aftermarket cross over pipes have, as users often report it ‘took the thong slap away’. To which they are referring the notorious 1VD-FTV V8 ‘thong slap’ noise through the exhaust.
- Unnecessary complexity. You are ‘fixing‘ an issue, you didn’t know you had. So, how big of an issue, is it really?
The potential problems carry on in the materials used to construct aftermarket cross over pipes. The OEM manufacture of this component has it DIALED in. All mounts line up. I’m yet to have seen one crack. I’m yet to have seen one break a flex joint. I’m yet to see one hinder performance, well into the 500HP mark on the 1VD-FTV engine.
The failures I have personally witnessed on aftermarket cross over pipes include,
- Cracked welds to the mounts that supports it
- Most likely due to incorrect alignment and constant engine harmonics of a diesel engine
- V-Band clamps eventually leaking after heat cycling (note: factory system is 1 piece with flex joints for a reason…)
- The use of poor quality, or incorrect flex sections for the cross over pipe.
- If using a stainless steel braid flex joint, we have seen this eventually break apart due to the extreme heat and eventually perish internally, giving it only one place to go…. through your turbo. If it doesn’t do that, we just see them bypass soot out of the braided flex itself. Keep in mind, your manifold pressures can run up to 60psi, an exhaust (where these flex joints are typically used) probably sees max of 2psi.
- Where we have seen the use of the correct style of flex section, unfortunately it seems to all go downhill long term due to the quality of the piece itself welded in. 99% of aftermarket manufactures experience in exhaust tubing and manufacturing comes from exactly that… exhausts. With the cross over pipe, you are essentially working with a manifold which goes through substantially different conditions. If your flex bellow in your exhaust breaks, lets say (to be vary fair) every 1 in 100 does break a bellow, it’s not the end of the world, it won’t pull a vehicle up, it can usually drive with an exhaust leak like this. Apply that 1 in 100 principle to your cross over pipe, your trips coming to a stand still pretty quick. A broken cross over pipe is a ‘park it up’ and fix it scenario, unfortunately. I suspect the higher rate of failure with these is again due to the constant pressure seen in the cross over pipe. When they are used for things like waste gates, or manifolds in petrol engines, they RARELY experience the consistent manifold pressure a diesel engine has, often don’t do the corrugated roads a 4wd does, nor the KM’s.
So, what does this all mean?
It sincerely means, leave the cross over pipe alone on your 1VD-FTV. The factory one has been designed PERFECTLY. I am ANTI a lot of OEM designs, airbox’s on a 70 Series and 200 Series Toyota Landcruiser being a key indicator of how an OEM can produce sub quality components, however, they got this one right.
But, what about HP and torque gains!?
Well, I’m glad you asked.
Our testing has proven them irrelevant. It makes no real world difference that we can demonstrate or distinguish apart from the noise of the exhaust, as mentioned above.
We actively remove these cross over pipes in 100% of situations that allow us too when doing performance upgrades on the 70 Series Toyota Landcruiser in our workshop. This guarantees our results with consistency in turbocharger response, guarantees the turbo won’t one day succumb to a piece of exhaust flex joint going through it, our customers don’t get 50,000km’s down the road and suddenly have a performance issue we could have jumped on the moment we saw it, and overall, leaves us with a 100% success rate.
Which, is one of the hardest things to achieve when it comes to vehicle performance.
For the costs (often $900+ not including fitting) save your money, and spend it on something else on your vehicle. Sometimes, shit gets made for the sake of making shit.
