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Twin Turbo V6...cooling

3K views 79 replies 18 participants last post by  Animal 
#1 ·
Hi gang....i need some advice ;)
Im part way into stripping down and upgrading a cally V6 engine which is going in to a GTE. I have 2 T3 garrett turbos and a good friend that can make up the exuast manifolds for me to fit the turbos on each bank...the problem im going to have is the turbo that is at the rear of the engine will get ruddy hot..will one of the bonnet scoops work ok or will i have to introduce some type of air flow mod to the engine bay?

cheers :beer:
 
#52 ·
Animal said:
lol, any up ur own bung hole gen. Just cos you're old doesn't mean you can't be wrong. :p
as in: "a million flies can't be wrong - YOU TOO are eating shoite!" :D
.. putting the turbo's after the supercharger is a good idea, as it'd decrease the efficiency of the turbo having to suck through a blower.
No it doesn't! the turbo operates on pressure differences.
If the compressor has to suck at -5psi (relative to sea level) because you're on top of a mountain or something, then it will have to spin up to make the difference to produce your 15psi booost (or whatever).
If you serve the compressor with already boosted meal (say at 10psi) then it will only make up the difference until 15psi. It will actually have an *easier* life
any 'In a proper setup, you do it my way' Gen? :p lol
:D
So it's YOUR way, or the motorway, right?lmao lmao :beer:
 
#55 ·
JohnA said:
as in: "a million flies can't be wrong - YOU TOO are eating shoite!" :D

No it doesn't! the turbo operates on pressure differences.
If the compressor has to suck at -5psi (relative to sea level) because you're on top of a mountain or something, then it will have to spin up to make the difference to produce your 15psi booost (or whatever).
If you serve the compressor with already boosted meal (say at 10psi) then it will only make up the difference until 15psi. It will actually have an *easier* life
:D
So it's YOUR way, or the motorway, right?lmao lmao :beer:


lmfao.

If I want 15 of boost, say the superchargers providing 10 psi, the turbo's would provide the extra 5 psi, as they're being controlled by the ecu which takes it's signal from the pressure after the supercharger.

In your explanation above, you say exactly the same thing.

if you have an obstruction in the intake of the turbo (which is what a supercharger dicconnected from the crank is), then the turbo's going to have to work harder (it needs to spin the supercharger with no help from the engine) to provide the same amount (volume and density) of air than it would if the turbo's had no supercharger to turn.

The advantage of the way I want to do it is that the turbo's have a less restricted intake, and its simpler, as there's no electromagnetic clutch needed, as the supercharger's never disconnected. sure, the supercharger needs to suck air through the turbo's when they're not boosting, but they have very little inertia relative to a supercharger.
 
#56 ·
0ddball said:
i'm pretty sure you know thats not the turbos fault, more due to the fact that the air flow metre is about a metres worth of induction away from the throttle body.
drive a turbo car off boost. compare it to a NA car, and i think you'll agree it's crap.

It's not the fault of the turbo, sure, but it's still slow, and throttle modulation is very poor.
 
#57 ·
The throttle repsonse of ANY standard (I mean without NOS, etc) turbo car compared to a NA is poor.

Nothing wrong with my MR2 turbo engine, and that runs from a temp sender + a map sensor instead of an AMM, but put your foot down and you still have to wait that 1/2 second or so..

2p, actually worth about 1p..
:beer:
 
#58 ·
your MR2 is the best I've driven yet, but like you say, it still leaves something to be desired in the response dept.

It's got some poke though! :beer:
 
#59 ·
I think that the most important factors here are vehicle weight and engine capacity - this as a ratio determines the off-boost performance and how much you rely on boost to take you through the gears.

A heavy car with a small engine (like the calibraT) cannot afford to go for high boost setups, because it will compromise the already dodgy off-boost "pull"

In contrast, a Caterham with a 3.0turbo CAN afford to run 7:1 CR etc because all these cubes can pull it's tiny weight easily, with no need from boost.

Now you're trying to use the supercharger as a direct replacement for cubes - say make the engine the equivalent of 4.0 liters or whatever. Depending on the final CR and the Manta's weight, it could be that you don't need all this complexity and aggro, and just the turbos are enough.
The transition where the supercharger backs off and the turbos take over will be tricky to setup properly.

I just wouldn't trust a supercharger drawing already boosted air just after a turbo. Superchargers don't have a wide operating range like turbos. Any boost spike will knacker it.:beer:
 
#60 ·
JohnA said:
I think that the most important factors here are vehicle weight and engine capacity - this as a ratio determines the off-boost performance and how much you rely on boost to take you through the gears.

A heavy car with a small engine (like the calibraT) cannot afford to go for high boost setups, because it will compromise the already dodgy off-boost "pull"

In contrast, a Caterham with a 3.0turbo CAN afford to run 7:1 CR etc because all these cubes can pull it's tiny weight easily, with no need from boost.

Now you're trying to use the supercharger as a direct replacement for cubes - say make the engine the equivalent of 4.0 liters or whatever. Depending on the final CR and the Manta's weight, it could be that you don't need all this complexity and aggro, and just the turbos are enough.
The transition where the supercharger backs off and the turbos take over will be tricky to setup properly.

I just wouldn't trust a supercharger drawing already boosted air just after a turbo. Superchargers don't have a wide operating range like turbos. Any boost spike will knacker it.:beer:
I agree that the weight and gearing are factors which will affect the engine design requirements.

However, what I don't want is any lag, and I want to keep the throttle response as crisp as is possible. Just think about cornering in the wet in a rwd car, and you'll see where I'm coming from.

I'm not interested in a turbo only solution for the reasons above. I want the turbo's to provide an additional boost at high revs when the supercharger starts to be less efficient. It's not a turbocentered solution, but a supercharger centered solution, and the turbo's are there to make additional power at the upper end of the rev range.

As the whole thing will be mapped boost, there's no reason why there'll be any boost spikes unless it's piss poorly mapped. and boost spikes are exactly what I'm trying to avoid.
 
#69 ·
hi gang....when i started this thread it was about cooling a twin turbo V6...Animal my main man has the same 'more power needed' gene as me..lmao
i to have two T3's and a Cally V6 which is going in to a GTE Bay (half way there)...heat is a big problem for me in the design of the block but i think with a good FMIC and a aqumist set up i might get away with it...also looking at 'ceramic' coating on the pistons???
Because of the bay restictions i might not be able to fit a Supercharger in...
Two T25's can be got if the T3's are to much and with such a light car i should be able to use both at a low boost..
If im not using the turbos then a wet nos system might be set up......or both turbos and noz..:eek:
 
#70 ·
lol.

you'll struggle to fit the turbo's... it may be worth you moving the rad forward, and cutting the bulkhead back to give you more access at the back of the engine.

Alternatively, run one turbo and put it on top of the gearbox. There really isn't much space with an xe in there, let alone a v6!

Turbo's and nos is a good combination. better spool up, and better cooling of the cylinders.
 
#71 ·
I would only use n20 for anti-lag, i.e. just run it until you reach a certain boost, and then just let the turbos give you the ultimate power.

Then you won't be forever running out, as you only need a very small amount to start the turbos going.

torque-peak-tastic though....

:beer:
 
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