Twin Turbo 928 fixed and back out there terrorizing the streets!
#1817
Nordschleife Master
Thread Starter
Tuomo, have you seen this Mazda VRIS study, perhaps nothing new for you but good write up.
http://web.archive.org/web/200312062...vwxyz_vris.htm
http://web.archive.org/web/200312062...vwxyz_vris.htm
In any case, the Mazda V6 intake is similar to many Porsche intakes that have a resonance flappy, including the 928 S4 intake. There are two modes, and they tune to different frequencies.
My plan is to fine tune the turbine A/R choice and the intake manifold resonance point such that the intake flappy-closed torque peak happens at the rpm where the turbine is just about to spool such that the knock limit is reached at the lowest rpm possible without sacrificing the high-rpm exhaust manifold back pressure. At high rpms, the flappy can be left open because the resonance effects are minor and because the throttle body flow resistance imbalance is mitigated by there being net air mass flow from one plenum to another thru the resonance flappy pipe.
#1818
Rainman
Rennlist Member
Rennlist Member
I used to have a car with that engine - very smooth power delivery and a great sound, FWIW...
Speaking of Porsche + Mazda V6, Porsche designed the original Ford Duratec V6 for possible use in the Boxster, then sold the design rights to Ford who tweaked it a little for mass manufacture.
Speaking of Porsche + Mazda V6, Porsche designed the original Ford Duratec V6 for possible use in the Boxster, then sold the design rights to Ford who tweaked it a little for mass manufacture.
#1819
Nordschleife Master
Thread Starter
#1820
Nordschleife Master
Thread Starter
Bumper adjustment
There is now enough clearance between the rear bumper and the tailpipe such that the bumper doesn’t melt during the first couple hundred dyno pulls:
#1822
Nordschleife Master
Thread Starter
Test pipes welded and a cheap thermal imaging system purchased:
Purely by coincidence, the "test pipes" that replace cats and work as exhaust blowndown supersonic shock wave traps happened to be exactly the right length for the spot. Better be lucky than good! Stainless steel, robot welded in Taiwan:
Then there's the question of heat shield design. We're planning to do the simplest thing, which is to drive the car hard and thermally image the engine and pipes from the top and bottom right after that. This should tell us if any sensitive components are getting any heat. Special attention will be paid on the valve cover gaskets, oil pan gasket, scavenge oil pump, and the starter motor. Below I used the system to turn my oldest into a ghost:
Purely by coincidence, the "test pipes" that replace cats and work as exhaust blowndown supersonic shock wave traps happened to be exactly the right length for the spot. Better be lucky than good! Stainless steel, robot welded in Taiwan:
Then there's the question of heat shield design. We're planning to do the simplest thing, which is to drive the car hard and thermally image the engine and pipes from the top and bottom right after that. This should tell us if any sensitive components are getting any heat. Special attention will be paid on the valve cover gaskets, oil pan gasket, scavenge oil pump, and the starter motor. Below I used the system to turn my oldest into a ghost:
#1823
Captain Obvious
Super User
Super User
I used to have a car with that engine - very smooth power delivery and a great sound, FWIW...
Speaking of Porsche + Mazda V6, Porsche designed the original Ford Duratec V6 for possible use in the Boxster, then sold the design rights to Ford who tweaked it a little for mass manufacture.
Speaking of Porsche + Mazda V6, Porsche designed the original Ford Duratec V6 for possible use in the Boxster, then sold the design rights to Ford who tweaked it a little for mass manufacture.
#1825
Nordschleife Master
Thread Starter
#1826
Nordschleife Master
Thread Starter
John’s about ready with the exhaust
Here’s the exhaust. While John Kuhn is putting the finishing touches on the exhaust, Im helping Olivia guard the basket against Orlando Magic:
#1827
Racer
Join Date: Jan 2009
Location: Adelaide South Australia'79 5spd twin turbo
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Given the mention of the Mazda K series engine, and the twin turbo theme I thought I might just throw this in the mix. This is what I've been doing lately, it is the back end of a 1988 F1 car mated to a Mazda KL and a tube frame chassis at the front. For use at my local hillclimb track.
#1828
Nordschleife Master
Thread Starter
Polished
The tip is now polished and all the pipe section dimensions recorded such that John can make more of these exhaust if people need the flow capacity and like the sound.
#1829
what are the details of the rear muffler? Dual 3 in and 3.5 out? I need to redo the back of my exhaust to fit around the z06 trans so I may as well add a muffler. I have dual Borla XR1 Race mufflers and it's a tad bit loud.
#1830
Nordschleife Master
Thread Starter
In terms of sound, the theory is that the infinity pipe and single out will help a lot. In theory, theory and practice are the same. In practice, we’ll see soon.
Last edited by ptuomov; 02-05-2018 at 12:13 PM.