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300 tdi engine tweeks in a 101


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Couple of years back i put a 300 tdi into my 101, it'll never be a rocket ship. But i wanted to make it more efficient if possible, so i fitted the largest universal intercooler i could find which is roughly 450x350 that would fit in the tunnel in front of the engine. Now i had to fit it back about 20 inches as this was the widest bit without pipes and steering relays in the way. I upped the boost a little after reading up on the net, so it'll come up to just under 1.5 bar now. If pushed hard on a hill the egt guage reads 600 (sender in blanked off egr plate) exhaust is 2 inch with universal silencer. Im now wondering as i cant fit the intercooler right in the front if some form of ducting to pass more air into the tunnel would help, maybe even a fan or bilge blower or maybe a bigger diameter exhaust. Just interested in some views on maybe what i should have done differently or maybe i should have left well alone.

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2 inch exhaust sounds to me like it could be hurting things power wise? let someone else confirm though.

600C is not that hot for the EGT, did you up the fuelling at the injection pump when you wound up the boost as well?

Some ducting will help the IC work better, though the gains are probably not as great as you might think.

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My mistake the exhaust is 60mm standard down pipe into stainless system. Yes i upped the fuelling and boost a little, the turbo was rebuilt six months back with T28 internals. But to be honest ive not noticed any difference. I hadnt fitted the EGT gauge before the turbo rebuild.

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Get the head redone by Turner Engineering - they reckon on an 11% performance increase, if I remember correctly. As for the intercooler, size is only part of the equation; it has to allow free flow internally and externally to be effective.

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  • 4 weeks later...

Fuelling.

Does it smoke much? The more fuel you can get it, the more it'll burn and the more power it will make. But it will smoke more.

I'd say you could certainly push the EGT's quite a bit more more for WOT.

A big exhaust will help keep the EGT's down and the flow up.

The IC can certainly aid IAT cooling, but won't really promote massive amounts more PEAK power. So I wouldn't worry too much about doing more to it. If you think air flow is restricted, just slap an electric fan on it.

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300TDI is quite limited I think you have done most things possible but as stated the exhaust will restrict things unless that is made bigger. You could change the cylinder head but I doubt you'd notice any performance difference in a 101, the next option is a VNT turbo however this is quite an expensive option but will give you power all through the rev range without turbo lag.

Are you using the LT95 gearbox and the 5.57 ratio diffs? If so you could change the transfer box ratio for the one from an LT95 RRC this would give a slight improvement. Another option is you could change the differential ratios to 4.7 this would give better cruising speed and a quieter cab, Ashcroft transmissions have a very handy ratio calculator tool that will show what effect changing both of these would have on your speed vs engine rpm.

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What is the weight of a 101, lighter than a disco or defender i would think. What box is it mounted to, gearing could be all wrong.

Would be interested in some photo's of the conversion and 101.

Weight isn't the biggest issue with a 101, more aerodynamics, it's a big flat front to push through the air.

A bigger exhaust, and have a play with the settings on the pump would be my first port of call.

There's a very good tuning guide for the VE pump here.

The EGT gauge you've now got will help if you're going to have a play with the fuelling also.

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  • 3 weeks later...

Thanks for the new comments, ive already changed the diffs to 4.7's for a little more top end. Im going to move the intercooler as far forward as i can now that the heater motor has gone. A lot of conflicting stuff on the net about exhaust sizing, was thinking of fitting a 3" exhaust but have read reports on it effecting the turbo spoiling up.

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Well, the diameter of the pipe will affect the relationship of pressure and velocity - increase one and the other decreases (basic thermodynamics). If you increase the diameter of the exhaust, the velocity of the gas will reduce, and that causes an increase in pressure.

An oversized exhaust will cause stagnation of the exhuast flow, which in turn causes back pressure, so it would cause a performance reduction, turbo charged or not. The diameter of an exhaust is far more critical than most realise, and is a function of the mass of gas flow, the length of the exhaust and egt, amongst other things. I'd stick to the standard 2.5" for a standard Tdi and up to 3" for one with all the tuning options like big intercooler, higher boost, fuel tweaks and VNT, but certainly no more. That's what cherry bomb exhausts do - they are so wide that they bring exhaust flow to almost a stop, increasing the back pressure until it pops and repeats that cycle - it sacrifices significant engine performance to do it, too.

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ive already changed the diffs to 4.7's for a little more top end.

Do you still have the 101 rumble from the front driveshaft on trailing throttle above 85kph after changing the diffs? The change should push the speed at which it starts to kick in to well above 100kph.

Garry

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Garry, its completely gone since i put the 300 tdi in. It could be because the front prop is 3" longer or the double cardan i fitted at the same time (i know this hasn't stopped the rumble for others, but it has for me)

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Garry, its completely gone since i put the 300 tdi in. It could be because the front prop is 3" longer or the double cardan i fitted at the same time (i know this hasn't stopped the rumble for others, but it has for me)

Thanks - could also be the extra weight of the diesel over the V8. But good to hear it has gone.

Cheers

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Not ignoring basic thermal dynamics at all, but in real world situations a bigger diameter exhaust 99% decreases turbo spool up times and EGT's.

We are talking about a 300tdi, it isnt a finely tuned race engine - by a very very long way.

What do you want out of your engine? more throttle response from idle, more top end or what?

Air filter postion and intake length make a HUGE difference and are easily modified.

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