[scorpian]

Why not use a engine degreaser to clean the intercooler and radiator? I usually buy a product manufactured locally and spray it using s spray bottle and then rinse it with a garden pipe . Can always see a lot of muck coming out and post wash its usually clean and shining like new.

[svsantosh]

Originally Posted by Dr.Naren

This is very interesting, never knew one could DIY a decat downpipe for just 1.6k

Actually the pipes may have costed 300-400 max and welding didn't cost anything, it was a pure DIY at a tbhp'ians home.

(Spot his MIG, Arc welders, air comp, and many more toys), ps - we were officially on-calls but playing with our cars!

[svsantosh]

WARNING - Do Not Try this Idea ever, even at your own risk. Lol

After the DeCat Idea a few months ago, one of the biggest drawback was lack of driveability and crappy low end torque. The turbo did not have enough zing left in it to pull the car forward and only at high RPMs it made any sense.

I work in a Turbo Machinery manufacturing organization and have learnt a thing or two about pressure, flow and etc etc...

Originally Posted by svsantosh

........Basic design criteria for any turbine is "Pressure, Temperature & Flow". The automobile turbo AKA turbine, is designed according to the pressure inside the.....

Decat & Backpressure issue.......in a DeCat the backpressure, or inlet vanes pressure is drastically reduced, while the exhaust gases temp & flow are more or less similar. This WILL CREATE a BIG PROBLEM in driveability...

The CHOKE Plate

I had to figure out a way to increase the back pressure inside the turbo via the Free Flow down pipe. The Catalytic Convertor builds back pressure at the turbo vanes by choking the output of the engine through its Honey Comb design. The built up of exhaust gases inside the entry of the Catcon and the time it takes to pass through the honey comb gives the oomph for the turbo vanes to spool and in effect gives the "boost" that pushes you into your seat or at least make it easy to drive in crawl traffic.

To cut short the gyan, I just had to choke the down pipe enough to make the turbo spool enough while at the same time not let the engine blow its head gasket. The DIY down pipe is a 2 inch pipe (so was the original catcon) and I made a choke Plate from some scrap SS (stainless) plate lying around.

2" down pipe means 50mm dia, and I eye balled 20mm should be just enough to create enough backpressure inside the turbo. Passed an end mill in my factory's machine and on the way back home caught up some like minded crazy car friends to fit it immediately to see if the idea works. After looking at the 20mm inside the 50mm (exisitng silencer) shim we felt its a tad too risky, and drilled out a 7mm hole next to it and further just made a oval'ish hole and we approximated a (20+7+??) 30mm'ish hole in a 50mm down pipe.



I know too much mid school math above, but basically I ended up with a 60% choke plate and was ready to test it and see if my car blows!!!

The end result is now I have a DeCat down pipe with 60% choke & enough and more back pressure that the car feels just like new. The Oopmh is back and boy' it is better than when I took the car from showroom 6 years ago.



The driveability is amazing and the best part is the turbo is hitting a sweet spot, so sweet that for the last 1.5Lac kms I have averaged only 18-19Kmpl, max was 20'ish.

Now my car averages 22kmpl... and this a 3,000Km report after the 'The Choke'.

The End

[CannedShroud]

Mods please move this to an appropriate location as per need. I was very confused as to where this exactly fits in.

Hi all, for the past few months I've been wondering to do some performance modifications to my car. The current option in mind is a Stage 2 remap with the necessary intake and exhaust changes, which include:

1. Free Flow Air Intake
2. Decat Downpipe Exhaust

I have a 1.2 litre turbo petrol engine (pretty small turbo) and was wondering about the aspects of driving that will change once (if) I go for the decat.

I understand the play of back pressure and how it helps engines mantain a constant stream throughout exhaust pulses, aiding low end torque.

What I don't understand is how does remove the cat cause any drop in low end power in a turbo car. (NA is self explanatory). In a turbo car, the cat comes after the turbo and the removal of such an obstruction to exhaust flow should only increase the RPM and or spool time of the turbo.


Apart from that I would also love to know your stories with stage 2 maps and decat cars.

Here are a few questions I have

1. What is the legality involved
2. Do you pass PUC?
3. What is your experience with performance
4. Any experience with Road trips outside your home state? Does the police stop you?

Thanks and Cheers!