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V8 Twin Turbo?


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Turbos. Diaphragms. Waste gates. Pressures. Don't do it!

The ones I'm thinking of using are a similar design to the Peugeot ones, where the waste gate is operated from the inlet vacuum. As for pressure wise, I'm not one of these ones that wants to put silly pressures through an engine, just enough to give it that extra bit of poke.

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There used to be a Janspeed Range Rover here. It was a beast and went like stink and then it blew up and nobody wanted to touch it so I think it's now permanently dead. Probably one of those "I'd fancy a go in one but wouldn't want to own it" things.

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I was speaking tongue-in-cheek about diaphragms etc, but you will need to pick turbos suitable for your engine's massflow and pressure requirement - it's not just a case of bolting on whatever you find. Then you've got to fuel it to ensure it doesn't go lean at high speeds, or you'll be playing a quick game of big bangs / melty pistons / "catch the conrod" etc :)

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I was speaking tongue-in-cheek about diaphragms etc, but you will need to pick turbos suitable for your engine's massflow and pressure requirement - it's not just a case of bolting on whatever you find. Then you've got to fuel it to ensure it doesn't go lean at high speeds, or you'll be playing a quick game of big bangs / melty pistons / "catch the conrod" etc :)

Exactly, this is why I have been speaking to fridgefreezer about management for the engine. I used to do alot with rally cars, like mapping, anti-lag and so I am quite capable and understand the importance of fueling and turbo pressures through rpm. We used to use g3 links from thaw racing, but these are a bit pricey.

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Deffinately just a play thing. It's one of those things that when you finish a project you get that nice warm sense of wellbeing feeling and then decide to start modifying even more. I am under no illusion that this is going to be easy. Just been back and looked at link website and I think I might just have to spend the extra money and get a G3 link. Has anyone had much dealing with these in this type of application? I have on other applications like Subarus where everything is there for you. Some of the main benefits for the link are you can control V8 on coil, 4D fuel mapping, does away with air flow sensors and if using a gm boost control solenoid will control all boosting for turbos. You can also get the upgraded model with a 5 bar map sensor but I think that's a bit too much for what I'm looking for. :lol:

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Back in the dim distant past ,(about 1985) Tom Walkinshaw racing had a twin turbo rangie , it had a coming to gether with a foden tipper at a junction whilst towing a trailer to or from silverstone , I had to tow the foden in . It had twin turbos and would smoke the tyres in third gear (constant 4wd) . So it can work ok. HTSH

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I was speaking tongue-in-cheek about diaphragms etc, but you will need to pick turbos suitable for your engine's massflow and pressure requirement - it's not just a case of bolting on whatever you find. Then you've got to fuel it to ensure it doesn't go lean at high speeds, or you'll be playing a quick game of big bangs / melty pistons / "catch the conrod" etc :)

Unless you read Practical Performance Car where the wise advice seems to be bolt any old turbo/supercharger/engine on to any old vehicle.

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Have I missed the description of what this is to be used for?

I don't think it has been mentioned so, A turbo setup by its very nature will bring in power higher in the revs which will be fine if the project is a race car.

If the project is a stump pulling 4x4 them a supercharger would be better.

So what is it to be?

Steve

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Have I missed the description of what this is to be used for?

I don't think it has been mentioned so, A turbo setup by its very nature will bring in power higher in the revs which will be fine if the project is a race car.

If the project is a stump pulling 4x4 them a supercharger would be better.

So what is it to be?

Steve

yes and no the truck is going to be used for off road and on road i'm going to use anti lag.

How ALS works

When the driver lifts his foot from the gas pedal the ignition timing is altered with sometimes 40° or more of delay (retard) and the intake air and fuel supply mixture is made richer. The inlet butterfly is kept slightly open or an air injector is used to maintain air supply to the engine. This results in air/fuel mixture that keeps getting in the combustion chambers when the driver no longer accelerates. The ignition being delayed, the air/fuel mixture reaches the exhaust tubes mostly unburned. When the spark plug fires, the exhaust valve is starting to open due to the ignition delay mentioned above. Additionally, the exhaust temperature being extremely high, the unburned fuel explodes at the contact of the exhaust tubes. Luckily the turbo sits right there and the explosion keeps it turning (otherwise it would slow down since its intake, the exhaust gases, is cut-off). The effect is vastly lower response times with some downsides:

*

A quick rise of the turbocharger's temperature (which jumps from ~800°C to the 1100°C+ region) whenever the system is activated

*

A huge stress on the exhaust manifold and pipes (mounted on a street car a bang-bang system would destroy the exhaust system within 50-100 km)

*

The turbo produces significant boost even at engine idle speeds

*

The explosions which occur in the exhaust tubes generate important flames which can, sometimes, be seen at the end of the exhaust tube

*

Reduced engine brake

The ALS effect is mostly dependent on the air allowed into the engine, the more air supplied the more the ALS effect will be noticeable. Consequently ALS systems can be more or less aggressive. A mild ALS will maintain a 0 to 0.3 bar pressure in the inlet manifold when activated whereas, when inactive, the pressure in the inlet manifold with the throttle closed would be in the region of -1 bar (absolute vacuum). Racing ALS versions can maintain a pressure of up to 1.5 bar in the inlet manifold with the throttle closed.

While the systems mounted in Toyota and Mitsubishi racing cars are relatively smooth and noiseless those fitted in Ford and Subaru cars are much more noisy and aggressive.

The bang-bang system owns its name to the loud explosion noises one hears whenever the driver lifts off. Most racing implementations have user selectable anti-lag settings depending on the terrain, usually three settings can be selected by the driver going from mild to very aggressive.

I believe with this system you should be able to run a manifold pressure of about 0.75 of a bar on closed throttle vastly reducing the throttle response time and reducing the amount of lag which is normally associated with turbos. And as for nos I believe the G3 link also can control nos fridgefreezer :ph34r:

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  • 1 month later...
just found this after a lengthy discussion about the same thing (convertaion mostly one sided i dont have a clue) so are you still going to try this ?? would be intrested to see how you get one

Yes, I have got the turbos and manifolds, was keeping stealth due to the negativity I have received for considering using turbos with the lag issues.

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Yes, I have got the turbos and manifolds, was keeping stealth due to the negativity I have received for considering using turbos with the lag issues.

Please crack on, there are plenty of us interested in the project. Don't worry about the doom and gloom merchants, there will always be people who don't agree. Only you know what you want to achieve.

Anyone who knows his onions will know that turbo lag doesn't need to be a factor if you choose the turbos correctly.

Turbos too big for the application will result in big power high in the rev band. Small turbos will give stump pulling power right at the bottom of the rev band but quickly run out of puff.

A combination of different sized turbos or VNTs can give power at both ends of the rev band and it seems you have a sophisticated system which will work too.

Carry on, and let us enjoy your project too!

Regards,

Diff

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Please crack on, there are plenty of us interested in the project. Don't worry about the doom and gloom merchants, there will always be people who don't agree. Only you know what you want to achieve.

Anyone who knows his onions will know that turbo lag doesn't need to be a factor if you choose the turbos correctly.

Turbos too big for the application will result in big power high in the rev band. Small turbos will give stump pulling power right at the bottom of the rev band but quickly run out of puff.

A combination of different sized turbos or VNTs can give power at both ends of the rev band and it seems you have a sophisticated system which will work too.

Carry on, and let us enjoy your project too!

Regards,

Diff

I'm sure turbo lag on a properly sized low pressure turbo won't be an issue.

Can't be like driving a 200TDi with respect to lack of power & lag.

I'd be interested to read about how you get on.

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