Supercharged V8 Landcruiser. What do I do with the exhaust???

[mickifa]

G'day Fellas,

I've got a V8 Landcruiser 100 series with a TRD supercharger (running 6 psi) and Pacemaker headers on it. I currently have a 2.5" single exhaust system on it but not sure whether its right for the car. I've had all sorts of different advice from exhaust shops on this. Just wondering if anyone has any thoughts on what I should put on it?

Was thinking maybe a 2" or 2.5" dual system with cross over pipe? Don't really want to lose power in the lower rev range.

Cheers, Mic.

 

[crushu]

I am running the same setup as you.

My LX470 has 200,000km's on it, and is a 99 model. I run a TRD charger, and it makes 6psi from about 3000rpm onward, with the air filter box disconnected. All hooked up, it is closer to 5 psi peak.

I also have Pacemakers, and a twin 2.5" press bent system, thru to a 2inlet, 1 outlet rear muffler. Sounds very tuff, but not overly loud. Like "Contained Rage".
What sort of power are you making? What ECU are you running?

Mine made 185KW with the box connected, but no element. I have removed the cap under the airbox, to let more air in. The US cars run a different airbox, that probably flows more. There is a Mod you can do to increase airflow into the Aussie spec box, hopefully I will do it soon.

 

[mickifa]

Hey Crushu,

Haven't had my thing dyno'd so not sure of the power but I know its way more than what I had! The ECU I used came with the original TRD kit. It is a self learning one that adapts to the way you drive the car over a period of time. This is what I've been told.

Cheers, Mic.

 

[crushu]

Cool, what year is yours?

I couldn't get a Landcruiser kit, so I bought one from a Sequoia (US F150 sized wagon) and had to use aftermarket ECU.

Have you actually measured 6psi? I only achieved 6psi with copious amounts of Belt Grip sprayed on, and no air cleaner.

Does the drive belt touch itself over the top of the tensioner?

 

[mickifa]

Mines a 2003 Cruiser. No, I haven't measured the PSI. The guy I bought it from in the states told me it was a Landcruiser kit. I got the feeling though when I was installing it that it may be a 2003 Tundra kit. But the ECU was definitely a Cruiser ECU.

Drive belt doesn't touch itself over the tensioner. Only drama I had with mine is that the belt didn't run staright over the idler pulley above the aircon pulley making the belt run up against the flange of the same and the belt squeeled its head off. Shimmed the mount plate for the idler pulley and that fixed the problem.

Cheers, Mic.

 

[crushu]

Mines a 2003 Cruiser. No, I haven't measured the PSI. The guy I bought it from in the states told me it was a Landcruiser kit. I got the feeling though when I was installing it that it may be a 2003 Tundra kit. But the ECU was definitely a Cruiser ECU.

Drive belt doesn't touch itself over the tensioner. Only drama I had with mine is that the belt didn't run staright over the idler pulley above the aircon pulley making the belt run up against the flange of the same and the belt squeeled its head off. Shimmed the mount plate for the idler pulley and that fixed the problem.

Cheers, Mic.

I would suggest that you do have the right kit, but the US LC's have the different air box, and a few other differences. If the ECU was correct, I think it all would be. Do0n't forget the TRD kit is a US domestic part, not worldwide.
I had exactly the same problem, and the belt was noisey as all hell, turns out it was not on the crank correctly, forcing it to drive forward, and squeal. I spaced the idler out too, but it would jump a row forward on the AC compressor.

Try reving the engine quickly, while watching the tensioner. I have fitted a shorter belt, and it still touches.

 

[mickifa]

I actually compared the landcruiser installation manual to the tundra one and thats where i noticed the differences. Also the kit itself had the tundra p/no on it. The only thing that had the right number on it was the piggyback ECU. Even the belt was for a Tundra. I knew about the airbox before I started and thought it would be a problem but didn't even have to mod it to get it on.

The belt walking forward wasn't anything to do with where it sat on the crankshaft pulley. I had to shim the plate that the idler pulley is mounted to so that the pulley ran straight. It ended up of he 3 mount bolts I shimmed 1 0.020", 1 0.030" and the other left the same and it fixed the problem. I also fitted a metal pulley and threw away the plastic one. So play around with shimming the idler pulley and it should fix your problems. If you need specifics on what shims went where i can let you know.

The supercharger has been on the car now for 50000kms and its been sweet ever since.

Cheers, Mic.

 

[JBrady]

Isn't the TRD a roots type supercharger? It should make boost from 1000rpm.

Much less worries about running dual 2.5" on your setup. The engine at 4.7 liters should not have near the low end issues that a 4.0 or even 4.3 has. That said a properly designed dual 2.0" system would support 400hp easily.

 

[crushu]

mmmm......I dunno about boost at idle, but it does ok from down low.

 

[JBrady]

mmmm......I dunno about boost at idle, but it does ok from down low.

I am not saying FULL boost but certainly some boost. The whole concept of positive displacement supercharging is a pump that moves more volume per engine revolution than the engine displaces.

At low RPM leakage around the compressor rotating lobes and the housing loose some of the pressure/boost that would otherwise be available. Open the throttle full and load the engine and you will probably see better than 50% of full boost off idle.

 

[crushu]

I agree there would be less vacuum, but no boost.

 

[mickifa]

As its a roots blower, doesn't less revolutions mean less psi? Isn't that why people put smaller pulleys on these things to increase the revolutions, thus increasing the psi?

Back to the original statement, thats why it creates a small amount of boost at idle and builds to the max rated (around 6 psi) at 3000rpm. I'm pretty sure i've seen the pressure vs RPM charts which show that. Will have to look into it.

Cheers, Mic.

 

[JBrady]

As its a roots blower, doesn't less revolutions mean less psi? Isn't that why people put smaller pulleys on these things to increase the revolutions, thus increasing the psi?

Back to the original statement, thats why it creates a small amount of boost at idle and builds to the max rated (around 6 psi) at 3000rpm. I'm pretty sure i've seen the pressure vs RPM charts which show that. Will have to look into it.

Cheers, Mic.

Actually... No.

To understand lets take out ALL the variables and apply the superchargers displacement and the engines displacement without considering any leakage or losses.

A Positive Displacement Supercharger (PDS) has a displacement just like an engine has a displacement. IOW, it MOVES the SAME amount of air VOLUME for each revolution. IF the PDS moves MORE air than the engine it is connected to PER REVOLUTION then this extra air volume backs up between the intake valves and the PDS creating pressure we call boost.

If these were the ONLY variables this supercharged engine would make the SAME boost at all open throttle RPM points. The supercharger drive assembly (assuming no belt slip) dictates that the supercharger RPM and engine RPM ratio remain the SAME at ALL points of operation.




As I state above a PDS displaces its rated capacity for EACH revolution. This is reduced at low RPM by leakage past the rotor and case sealing edges. This leakage becomes a progressivly smaller percentage of loss as RPMs rise.

At higher RPMs the aerodynamics feeding the supercharger become less effective and the supercharger volumetric efficiency starts to reduce total flow capacity.

The engine also has an important role in the boost "curve" of a PD application. At low RPM an engine displaces LESS PER TWO REVOLUTIONS than its bore x stroke x cylinders shows. This is due to cam timing as the exhaust closes after TDC and the intake closes ABDC. At high RPM and engine gives up flow to aerodynamic and other dynamic restrictions. Engines flow the HIGHEST PER REVOLUTION at peak torque.

If you take out the leakage of low RPM and the reduced volumetric efficiency of high RPM the "theoretical" boost curve of a PD supercharged engine would be absolutely flat.

 

[mickifa]

Fair call. I can see where you're coming from.

But i'm more interested in what to do to get those exhaust gases through the engine and out the back. Any chance we can steer the forum back that way???

Cheers, Mic.

 

[crushu]

Well, I have a twin 2.5" press bent system, from the extractors back, no cats, 2 resonators, 2 twin in, twin out centre mufflers, then a twin in, twin out rear muffler.

Sounds great, not too loud, but very tuff.