Re: [Amc-list] 'Rear Mount' Turbos - cat scratch fever -

[Wrambler242@xxxxxxxxxxx]

This reminds me, I need to look in the shed for the turbo for Jim....in Florida...
Oopsie...

--
Mark Price
Morgantown, WV
1969 AMC Rambler, 4.0L, EFI, T-5
2004 Grand Cherokee Laredo, 4.7L, Quadratrc II
" Chronic Pain Hurts"

 -------------- Original message ----------------------
From: Brien Tourville <hh7x@xxxxxxxxxxxxx>
> To work best, a rear mount turbo would have completely different turbine 
> designs than a front mount type, to allow for the slower, and less 
> energetic exhaust flow.  Simply bolting a normal front mount turbo to 
> the end of your exhaust will have very poor efficiency.  I'm assuming
> that the folks selling these kits have done their homework and are
> sizing the turbines as best they can, given that the majority of "off
> the shelf" components will be sub-optimal for their purpose.
> 
> The other problem that I see with a rear mount system, is the long lag
> time that it will suffer, trying to pressurize the intake system volume.
> Front mount systems all have some degree of lag, and with a rear mount,
> you're adding 10+ feet of 2-3 inch piping volume into the equation.
> That's a lot of volume to pressurize, and I suspect that these 
> systems suffer a lot of lag....
> 
> of course, your mileage may vary!
> Dave 
> 
> 
> 
> 
> <>
> 
> 
> 
> 
> The Toyota V8 car guys love the rear mount Turbo[s] 
> [ 'Rear Mount' being 'Under the Floor' - not after
> or even near the Convertor / Muffler ]
> 
> check the www.lextreme.com site - there are a few
> great Installs documented with Photos there.
> 
> The main reasons they go for this is Space - 
> there isn't any under the hood unless you
> send the Exhaust forward - which takes
> dedicated headers, etc.
> 
> 
> The biggest problems with these under floor installs
> is oil draining out of the Turbo[s]:
> 
> you need to 'valve' control restrict the oil entering the Turbo and
> to design in enough of a 'drop' for the oil return
> tube to allow the oil to get out of the housing -
> elsewise you've a cloud of smoke coming from
> oil backing up into the Turbo past the seals. 
> 
> Exhaust pipe I.D. AFTER the Turbo should be large -
> like 2.5 to 3" - no back pressure on the Turbine
> and use a big I.D. high flow Cat.
> 
> Mufflers on Turbo engines are usually omitted
> since the Turbo quiets things down before the Cat.
> 
> 
> The Exhaust Header to Turbo flange pipe I.D. is kept smallish -
> like 1.75 to 2 inch to keep pressure up - 
> and the run from Header Flange to Turbo
> Flange is dictated by your available space - could be next
> to nothing.
> 
> Placing the Turbos almost directly on
> the Header Flange - is preferred as your best 
> 'under floor' space is the area almost 
> in front of / beneath the Firewall.
> 
> From the installs documented on Lextreme, they weren't
> too picky on Turbo Sizing - something off a small 4cyl.
> as the Toyota V8 is a 4.0 - making any MR2 Turbo 'fair game'.
> 
> Throttle Response from Testimonials is very good -
> remember, these are street cars - not thinking in
> thousandth or even tenths of a second lag.
> 
> Imagine your engine with 50 to 100 extra HP/ Torque -
> and the type of Power Delivery with a Turbo is 'different'.
> 
> The 'normal' compression ratio hasn't been changed -
> pistons are cast - so off idle engine response is
> as it was - until the Turbos kick in around 2k RPM -
> then the 'Grin Factor' gets Stupid.
> 
> The engine isn't 'winding up' pulling in fuel then generating
> power - the fuel is 'stuffed' in -  the engine is being forced to make RPMs -
> the sound of the power generation is 'reversed' -
> it is 'weird and wonderful' - a totally different feel / experience
> to acceleration - it's "Dirty Bird" ;)
> 
> There's some video on YouTube.com of these if you're
> energetic enough to Google yourself.
> 
> 
> 
> 
> 
> 
> -- 
> 
>                   Brien
>             NEW YORK
>      eagle registry #501 
> eagle kammback registry
> 
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