Thread: Allisport stuff.

Originally Posted by micksta1973

Slowly getting there. Pic of the Allisport direct replacement I/C next to the new front mount. Another of it in place, and one of the plus 70mm rad. Turner gas flowed head just went on, new injectors ordered. Once that's all here and fitted it goes off to get the VNT turbo sorted.

Is that your direct replacement I/C, and if so, are you looking to offload it?

BTW, thanks for the write-up, great job.

You should adjust the timing with a dial gauge. Do not rely on the pin method. It is not accurate.

Finished the new hose that goes between the turbo and I/C. Fitted the EGT probe. Just need to fit the display and wire it up. Had a massive air pocket in the small hose that comes off the main lower rad hose and clips at the rear off the shroud going up to the expansion tank. Also my new temp sensor was faulty, bugger. Had to run around and managed to find a second hand one that still worked. New thermostat also didn't work, luckily I found one at a shop here. We had to run the system without the thermostat in to get the coolant to circulate and remove the trapped air. I raced home and got a little pot and a camping stove, plus my laser thermometer to test the replacement thermostat. That worked, so it'll go in Monday to check all is working. Boost gauge is connected up but it's just running through the passenger window, sitting on the dash. Need to fit that too. Only got 13-14 psi on first test drive. Should be 18+, but I think the snorkel to air filter hoses may be a problem. I hope the nugget stuff air box cures that due to the larger diameter hoses. Baby steps.

All finished. Had a bit of a panic due to a large air pocket in the cooling hoses that freaked us out a bit. Then had the temp gauge fail, so I had to replace that with a VDO gauge and sender. Boost gauge has been fitted into the dash with new temp gauge. All new Mercedes fuel lines fitted, and rebuilt Injector pump. Pump is set to 89cc on full boost, standard was 71cc. Full boost fuel comes on at 0.4 bar. Advance 0.3mm higher than spec, 1.58mm after start of delivery. Next will be 3 inch exhaust off dump pipe, finishing with a 2.75 straight through. I still have to fit the Nugget stuff intake and get a dyno tune. That will require a bit of saving up. Hopefully it'll all be done in the next month. As to was it all worth it, I'm not too sure atm, it's certainly quicker now, but only pulling 15psi. I think the new intake pipe diameter will help a lot, as will the dyno tune. The new turbo pipe looks snazzy and doesn't need a bracket to hold it in place due to the stiffness of the silicon hoses, plus it doesn't have the restrictive notch of the OEM pipe. I'll post up more as it progresses.

Looking good!

You should get 20psi out of the turbo technics vnt with your boot in. Warranty is void with snorkel, which suggests it might be holding you back. Otherwise you might need to give it more fuel.

I removed the snorkel on mine, 3 inch intake piping, 2.5 inch exhaust. It maxs out at around 21psi.

Good informative thread, engine looks great!

Pulled the snorkel off to see if a lack of intake air was the reason why I can only pull 14psi. No difference. Fitted a 2 & 3/4 straight through exhaust, no difference, egt's have gone up a bit though, which I'm guessing is because the gases can now leave a lot faster instead of stalling in the exhaust. People that have fitted this kit, or mechanical gurus, any idea on why the boost is so low? Fuel pump is tuned to provide more than enough fueling. Definitely faster (for a 300tdi) but not what it could be with a few extra psi. Could it be as simple as adjusting the actuator rod on the turbo? I'm most confused. Once I sort out the intake issue I can finally get it tuned on a 4wd dyno and see what difference the mods have actually made. Last dyno run at the wheels was 34.4hp, and 104ft/lb on 285/75 16 Federals. Huge eh?

All I know is that I had the same issue after install with PSI around 14-16. Only after I turned up the main fuel screw and put my boot in it did I see 20+psi. Tweaked the main fuel screw too far and witnessed 30psi!

Smoke off boost is likely to be a problem when turning up the main fuel screw, but if you turn up the main fuel screw so you see a haze of smoke ON boost - you should see some added PSI.

Here is my most recent method for setting fuel for a 20+psi VNT:

(mark and count adjustments in case you want to reset and try again)

• Use a Morgan Hill type boost pin - Or rotate the stock boost pin so that the steepest side is facing forward (on the pin).
• Wind the smoke screw on the boost compensator all the way out so that it does not push the boost pin down at all.
• Disconnect the air line from the boost compensator.
• Wind up the max fuel screw so that you can drive hard off the line comfortably in first without too much smoke. You are only looking at the first 1500rpms before boost would otherwise kick in.
• Reset your engine idle to around 800-900 by adjusting the screw on the throttle arm.
• Remove the boost pin from the boost compensator housing and turn the star wheel a few turns to raise the spring base and INCREASE the amount of force required to depress the compensator pin.
• Coat the pin in some coloured paste/grease, and re-install.
• Attach a pump (mittyvac or the like) to the boost compensator air line and add ~14 psi to the line. Remove the pin and check how far down the fuel restriction pin travelled along the pin. You need to repeat this process until you have set the tension on the spring so that it requires around 20psi ( a decent starting point ) to fully depress the pin.
• Take it for a drive, if too much EGT/boost/smoke add more tension to the boost spring to further restrict fuel delivery on boost. Or less tension if you are smokeless and down on boost.
• If at any stage after setting the max fuel screw you decide to rotate the stock boost pin to a less aggressive angle, it will change your off the line fuel setting. To fix this you could wind in the smoke screw on the compensator a bit. But its probably better to preserve the full range on the pin and go back and reset max fuel.
• Whilst tuning I suggest you set an EGT alarm to 700C and have your foot back off immediately when it sounds.
• There is a fair bit of trial and error in this method, but you should find your way to a happy balance.

Once you have the right max fuel setting, setting the boost pin orientation and tension so that there is no smoke all the way through the boost range can be tricky. You might get better results with a morgan hill type boost pin. Unlike the stock pin it can travel all the way from full restriction to no restriction.


Good luck. Looking forward to the Dyno results!