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REAR MOUNTED TURBO??


imprexa99

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LAAAAAAAAAAAAAAAAAAAAAAA...

 

*breathes*

 

...AAAAAAAAAAAAAAAAAAAAAG!

 

 

 

Seriously, that'll lag like an utter bitch due to the length of pipework involved and be horribly undriveable. There's an E60 M5 running around with a twin setup like that which at least has 5L of V10 to try and get it going, and yet I still can't believe it's anything other than utter gash and a way of engineering a problem when we already have an under-bonnet solution.

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LAAAAAAAAAAAAAAAAAAAAAAA...

 

*breathes*

 

...AAAAAAAAAAAAAAAAAAAAAG!

 

 

 

Seriously, that'll lag like an utter bitch due to the length of pipework involved and be horribly undriveable. There's an E60 M5 running around with a twin setup like that which at least has 5L of V10 to try and get it going, and yet I still can't believe it's anything other than utter gash and a way of engineering a problem when we already have an under-bonnet solution.

 

+1 :lol::lol::lol:

 

LAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAG!

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The rear mount set up is a good one! There is no more lag than the under bonnet options as the rear mount uses a 0.62 AR hot side on the exhaust.

 

Also as the turbo is away from the engine heat the intake air temps are very low.

 

Its a cheap set up that can be fitted in a day unlike the twin kits that need you to remove the engine.

 

On the plus side they sound cool as hell too!!!

 

http://uk.youtube.com/watch?v=Z47z7OCHti8

 

 

 

 

 

LAAAAAAAAAAAAAAAAAAAAAAA...

 

*breathes*

 

...AAAAAAAAAAAAAAAAAAAAAG!

 

 

 

Seriously, that'll lag like an utter bitch due to the length of pipework involved and be horribly undriveable. There's an E60 M5 running around with a twin setup like that which at least has 5L of V10 to try and get it going, and yet I still can't believe it's anything other than utter gash and a way of engineering a problem when we already have an under-bonnet solution.

 

+1 :lol::lol::lol:

 

LAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAG!

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Surely there must be more lag - there is probably 3 times as much air to compress in that system than a front engine mounted one which obviously takes longer to get presurised.

 

Also how the hell do you keep the inlet dry? It looks like it has some cover over it but under there its going to be drenched compred to the inlet location on the normal car.

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Also how the hell do you keep the inlet dry? It looks like it has some cover over it but under there its going to be drenched compred to the inlet location on the normal car.

 

That would be my main worry with it. The amount of rain that we get over here I wouldnt like to be running a turbo in that location :surrender:

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LAAAAAAAAAAAAAAAAAAAAAAA...

 

*breathes*

 

...AAAAAAAAAAAAAAAAAAAAAG!

 

 

 

Seriously, that'll lag like an utter bitch due to the length of pipework involved and be horribly undriveable. There's an E60 M5 running around with a twin setup like that which at least has 5L of V10 to try and get it going, and yet I still can't believe it's anything other than utter gash and a way of engineering a problem when we already have an under-bonnet solution.

 

+1 :lol::lol::lol:

 

LAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAG!

 

 

+1 LMAO :lol::lol:

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This isn't a bad kit...but not one of the better ones as there have been issues with some of the set-ups for different reasons. Here's the huge main thread from my350z that is dedicated to this set-up.

 

http://my350z.com/forum/forced-inductio ... hread.html

 

STS (Squire's Turbo Systems) has been around quite a while and their main forte is Corvettes, Camaros, and other domestics here in the states.

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The rear mount set up is a good one! There is no more lag than the under bonnet options as the rear mount uses a 0.62 AR hot side on the exhaust.
\

So? As Rob said, you've got so much more pipework there that no matter what you do with the turbo you will have more lag simply due to the laws of physics.

 

It's a solution that will only ever start to work with very large capacity engines, something which US muscle/sports cars have in abundance. If you fancy waiting about half an hour for the turbo to finally spool then they work well, but if you want something that remains vaguely drivable then there are a million better options out there.

 

IMHO, obviously. ;)

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Theoretically, yes, the should be more lag. In actuality...there isn't. Look at the dynos on it.

 

How do u discern lag from a dyno????

+millionty

 

It's like when people say that a correctly-sized twin-turbo setup doesn't have any lag, when due to the very nature of the kit it has to. Any rear-turbo kit will have between 3-4 times the lag of a similar front-mount setup due to the increase in pipe lengths.

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The dyno's show the boost pressure. The spool is how fast the boost goes from vac pressure to +ve pressure.

 

The smaller AR hot side has a smaller area around the turbine. The smaller area increase's the pressure on blades of the turbine. This high turbine pressure makes the turbo spool faster than if it were to have the lager 76 or 82 AR that most of the under bonnet options have. the lager AR exhaust spools later but does not choke out the top end by becoming a restriction in the exhaust. (cut back blades do the same as a lager AR exhaust housing)

 

The length of discharge pipe work to the throttle does not effect spool but it does effect efficiency. You get a lager pressure drop from the long pipe work. 8psi at the turbo outlet may only be 7psi in the intake manifold.

 

Saying the rear mount turbo has 3-4 time the amount of lag the twin kit has is ridiculous! The aps twin kit for example makes 7-8psi by around 3k rpm ? does this mean the rear mount turbo would have not spooled by the red line? lol..

 

Dynos prove the kit is responsive. I agree the lager the displacement the fast the spool (or the lager the turbo you can use) but the rear kit is design for low ish power use. 450whp top this is due to being restricted by the small exhaust housing on the turbo.

 

Hope this helps guys.

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I feel ZMANALEX could contribute here.

 

Dyno's only show the results of what happens at the wheels, when you plonk your boot on the "fast pedal". They don't measure how long/fast it took to get there!

 

could you rephrase the post in lamguage i can comprehend

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Can you not see where the torque hits on a dyno? ie. I the torque curve goes mental at 3k revs then the turbo has spooled.

 

From the dynos on my350z it looks like it spools at around 3700 rpm.

 

Correct me if i'm wrong though - i'm just guessing.

 

Oh, and them kits sound :cloud9:

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The length of discharge pipe work to the throttle does not effect spool but it does effect efficiency. You get a lager pressure drop from the long pipe work. 8psi at the turbo outlet may only be 7psi in the intake manifold.

I disagree. The pressure will be exactly the same regardless of length, as 8psi is 8psi. The difference comes from the fact that the turbo has much more space to fill, hence it'll need more time to fill the pipework so you will have more lag than on a conventional setup.

 

If you're getting a pressure drop of that magnitude, then the turbo is incorrectly sized and can't keep up with the flow of air that is being asked of it, or the wastegate/boost controller is poorly set up. In my experience of turboing cars using aftermarket kits on an MR application, even reducing the intake length from maybe 2m to 1m (going from an IC setup to a CC one) on a GT28R on a 1.8L, the lag time was significantly reduced. Like I said, with a large capacity engine you have far more torque available from lower down so you reduce the feel of the lag, but as the engine size decreases this gap will be far more noticeable.

 

 

Assuming the turbos are of equal-ish size (which they are given the estimated power outputs), then if one has 3-4 times the length of intake pipe than the other then it also has to have 3-4 times the lag.

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well, this set me thinking..... :teeth:

 

1. I drive a moderately boosted twin turbo @ 6.8 PSI

 

2. I disagree with several stated points here, notably that twin turbo's MUST lag. mine doesn't...

nor does that of a notable fellow member whose opinion I sought.

 

3. The length of pipe needed, and the resultant volume to be filled before

boost comes up surely MUST cause lag in the STS setup

 

so I plotted data I took from my dyno and that of the STS at a slightly higher 7 p.s.i.

compareAPStoSTS.jpg

It proves a couple of points I think.

 

a) I must be a sad basta*d to have botehered doing this. :blush:

 

B) The STS Power comes in much later and higher in the Rev Range.

It might suit some styles of driving, but I like getting a kick in nthe back at 2000 rpm.

and the STS imho just wouldn't do this... :surrender:

 

Elvis has left the buidling... :wacko: goodnight!!

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Martin, hate to throw a spanner in, but unless these runs were done at the same time on the same dyno, it doesnt mean an awful lot. Dyno readings can vary widely, let alone on different dynos in different countries.

 

I would agree however, that the extra amount of pipework in the STS kit will lead to more lag, and going by your plots, I'm suppirsed its only about 500RPM behind your TT in spooling up ;)

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Martin, hate to throw a spanner in, but unless these runs were done at the same time on the same dyno, it doesnt mean an awful lot. Dyno readings can vary widely, let alone on different dynos in different countries.

 

I would agree however, that the extra amount of pipework in the STS kit will lead to more lag, and going by your plots, I'm suppirsed its only about 500RPM behind your TT in spooling up ;)

 

I know what you mean about different dyno's Chris.

But the plot shows exactly what both you and I et most expected.

 

hu-u-u-u-u-gggee lag!

 

so not exactly a spanner, more tweezers!! :p

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  • 1 month later...

i have to point out rwd and rain dont mix.....when you add forced induction....and the narrow roads here in the UK....thats a collision waiting to happen sooner or later.

 

Unless your driving from london to new york(through the atlantic ocean) you wont have any problems with the kit and rain. I guess offroad driving in a 350 is the thing to do now a days :teeth:

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  • 7 months later...

I have just seen this post from old.

As a new member i dont want to say to much.

but i have seen a z32 300zx.

in the uk with this system fitted and it worked brilliant with No Lag.......

and made 80% more power when done with out any fueling mods.

His dyno was 348.9 BHP @ 6300rpm

non boosted power was 192.7 bhp @6500rpm.

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