To intercool or not ?

[DieselMonkey]

Guys,

Should i go for it now and build / fabricate the intercooler in front of my radiator or is there a possibility that it might hurt performance with a pressure loss across the system / pipework.

Its quite a lot of time and money, but if experience shows its worth it, let me know. I was all on to do it, but looking at my motor finished on the stand, it would be so much easier to just route a Stainless pipe right to the intake.

Remember i'm running a N/A 1.9 pump with a Garrett GT15 TDi turbo, the extra lengths of tubing and intercooler capacity will of course slow down the air charge, i'm just thinking that with the fuelling turned up quite a bit to get some decent power, with all that pipework, it will be smoking a lot longer, with a short run of pipe and raised boost pressure, smoke would hopefully clear up quickly.  

One other thing, on my daily driver, a 1996 Vento (mk3 Golf, (US -Jetta)) i turned the fuel up quite a bit and got a great power increase, but i also experienced some annoying idleing habits. They would generally be different from day to day. It has automatic control of the cold start device and advance, and i think i may have a weak thermostat or faulty temp sender so this may be to blame for this...but i also found that if you rev the motor, the revs fall very slowly compared to stock, this makes gearchanges less pleasent etc... with some adjustment idleing is better, usually 990, 1000,1025 & never been higher than 1100 esp. after a hard run, but the way the revs are falling is bothering me and i dont want the same thing to happen to my Golf project. Is there anyway to get the revs to fall quicker ?

I used the min. fuel screw and the cold start screws at the back of the pump both to get the idle back down. Any info much appreciated.  

Regards, DM

[TDIMeister]

An intercooler is NEVER a bad thing.

[QuickTD]

The added lag from the intercooler is negligable. When you consider that the 1.9l engine is consuming nearly 3000 litres per minute of air at 3000rpm, the 5-10 extra litres of air in the piping is hardly relevant. The pressure drop can be avoided by using generously sized piping (2" is good), mandrel bends and as few connections as possible. My engine lost less than 1 psi after installation of the intercooler.

Your high/inconsistant idle and slow engine decelleration are characteristic of excessive residual pressure on the intermediate/main springs of the pump governor. All you need to do is back out the residual adjustment screw (the screw that the throttle linkage rests on when at idle) until the idle speed either stops decreasing or hits about 750rpm, then back it out a further half turn. Make sure there is sufficient slack in the accelerator cable to allow the throttle lever to move freely during this procedure. You can then set the idle to spec using the normal idle adjuster at the back of the pump.