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Adding an interccoler?


Datsunman
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I notice that when first started and the engine is still cold the TD27T in my Terrano pulls noticeable stronger than when warmed up, especially evident when towing. I'm guessing this is down to the increased intake temperature once it's hot so how do I go about adding an intercooler? Do I need to adjust fuelling to allow for an IC or can I just install one and plumb it in? I've never dabdled with turbo diesels before so appologies if this seems like a dumb question! :wacko::D

 

Cheers,

Ed

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I was thinking of adding one from an Isuzu Piazza (I think that's called an Impulse in the US) which is a core about 8 inches square and maybe 2.5 inches thick so not huge but I'm lead to believe, quite efficient.

 

Time to start reading up on diesel tuning!

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Datsunman,

yes bolt one on but it needs good airflow to work well. I have fitted one on top with a Nissan Patrol bonnet scoop and a fan for when I am going slow but working hard (beach / sand driving in the Summer). I discarded the whole crossover pipe from the turbo to the manifold including the butterfly valve (the thing that looks like a throttle body and valve is for pollution control).

 

dsc01669pw.jpg

 

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Fuelling is increased by a boost sensor on the back of the fuel pump, so you do not need to adjust it. This in connected by a small rubber pipe from the bend on the inlet pipe and runs down between the manifold to the pump.

 

You can fit new injectors and check the fuel pump timing and this will also make a big difference (cut black smoke and increase power).

 

Bigger exhaust also helps and better intake / filter.

 

Geordie

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Thanks for the info :aok: I've wondered why some diesels have a throttle body and some don't before. At part throttle at about 65mph mine seems to make a faint high pitched whistle which dissapears if I either increase throttle or back off a little. Ditching it would be an easy fix for that :D I haven't yet looked into a location for the IC but you top mount looks pretty good.

 

I need to get a new exhaust soon anyway as mine is getting some perforations in it here and there. I'll be getting a custom made stainless steel one done for it ..what sort of pipe diameter should I go for ... would 2.5 inch be okay? I have a K&N filter I can use on it already.

 

My engine has only done about 67,000km from new and seems to have been regularly serviced according to the paperwork so I'd guess the injectors would still be pretty good. Do you think it'd still be worth fitting new ones (or getting them rebuilt?) My neighbour runs an engineering place that specialises in overhauling diesel pumps and injectors so getting them done should be no worries.

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Hi Datsunman,

I have 2.5" exhaust and it seems to be plenty big enough. Mine starts from the flange at the bottom of the wastegate dump housing so that is the main restriction.

 

If you can get a 3" dump section made from the back of the turbo then bend down to 2.5" pipe that would greatly reduce the restriction of the housing.

 

Servicing the injectors usually involves reolacing the tip section and needle to get the best spray pattern. If you have a friend in the buisness it would be worth it.

 

My Terrano had been driven around in Japanese traffic for the first 50,000km of its life and was very carboned up in the inlet manifild. I removed this to clean it out and blocked the EGR (exhaust gas recirculation) valve at the firewall end of the manifold. I also fitted an oil breather 'catch can' with nice big diameter 3/4in dia breather hose. It has now done over 200,000km and is clean in the intercooler and manifold.

Edited by geordie4x4
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If you can get a 3" dump section made from the back of the turbo then bend down to 2.5" pipe that would greatly reduce the restriction of the housing..

Geordie, do you know what type of turbo is fitted? I just wonder if there's an aftermarket dump pipe available for something else that would fit. There's so much heatshielding around the turbo it's hard to see what type it is. If not, the guy I use to get stainless exhausts done should be able to fabricate one up.

 

I did wonder about removing the EGR from mine as I don't need it to be legal or roadworthy here. Is it beneficial to do so?

 

Cheers,

Ed

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I've wondered why some diesels have a throttle body and some don't before.

Datsunman this has to do with the type of diesel motor. ie Direct Inject or Indirect Inject.

 

Indirect Inject will usually have a TB to control the amount of air thats going in and a small controller to control the amount of fuel going in.

 

Direct Inject usually get a full glup of air all the time. and the accelerator cable goes straight onto the injection pump to control fuel.

 

Directs produce more power and run more effeciently. Indirect Inject are smoother and quieter.

 

as for physical difference in motor. its a difference in heads.

Indirects have a head with a Pre-combustion camber, and this tends to be a week spot when running BIG boost. this is a small chamber above the cylender.

Directs - the air and fuel are injected directly into the cylender, hence the term direct inject. a lot better for BIG boost.

 

the TD27 & TD42 are both Indirect Inject.

Edited by sw
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Thanks Drift,

You could always fit a turbo or supercharger to your V6 and an intercooler BRMMMM. Nice mud puddle photo too, I can’t get my wife to wade through the mud to get a good photo for me.

 

 

Datsunman,

I am not sure of the turbo flange I think I heard on the WD21 forum it is an IHI turbo with T3 flange but not certain.

 

Regarding the EGR valve it is supposed to help reduce Nitric oxide (NOx) emissions by limiting high temperature oxygen rich burn of fuel. Particularly on deceleration and at idle the valve opens to let some exhaust gas back into the inlet manifold. The down side is that it creates more black sooty exhaust at idle and soots up the inlet manifold, ports and tops of the valves.

I have an exhaust bag jack and it would not work with the EGR valve. When the jack was connected and the vehicle in Park the valve is open and the extra back pressure forces too much exhaust back to the inlet, stalling the motor. But now it works well.

 

 

SW,

Thanks for that, I have built a lot of petrol motors but have not had a diesel appart so was never really sure what the indirect injection setup is.

I hope I have not done something silly by removing the throttle body. But that was 140,000 km ago and it is still going well.

 

Mine had the throttle connected by a vacuum hose and only seemed to close when it was at idle or on deceleration. otherwise it was wide open (I checked with a vac gauge while driving).

 

The accelerator cable goes directly to the back of the fuel pump and there is also a boost controlled servo that increases the fuel with the boost.

 

Geordie

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  • 3 weeks later...
Guest fascar

Dear all,

 

I also own a 1992 nissan terrano(looks just like a pathfinder). It has the td27t engine.

 

geordie4x4,

 

did the intercooler mod work? and what is the difference in performance. your feedback would help me decide.

 

fascar

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Hi fascar,

the short answer is YES it has made a heap of difference.

 

I get better low down torque when towing a trailer and better top end power.

 

Diesels love cool air and you will notice a distinct drop in performance on a hot day. The intercooler helps reduce this drop in power IF it has enough airflow or cooling itself.

 

I have done a range of other mods to assist the cooling, air intake turbo and exhaust and the combination makes a notable performance increase despite the bigger wheels I have fitted. I had a drive of a stock standard manual Terrano with smaller road tyres last week and realised how sluggish mine was before doing any mods.

 

If you are in a cool climate just fitting an intercooler and better exhaust will help. If like me, you live or travel in hot conditions you need to do a bit more.

 

Top mounted intercoolers are not the most efficient set-up, however in a Terrano that suffers from a bit of turbo lag you do not really want to increase the length between turbo and inlet manifold any more than you have to. There is not much room in front of the radiator to fit one there.

 

If you want to keep it cheap then a simple second-hand cooler on top with an air scoop will do the job.

 

Geordie

 

gc1844burrupge7.jpg

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Guest fascar

Geordie4x4

 

Thanks a lot, I am all for it. I too live in a very hot part of the world(Pakistan). The exhaust pipe on my ride is 2.5" all the way. here we get intercoolers for mitsubishi or toyota, any preferences there?

my only concern is ???cfm airflow thru the intercooler to the intake manifold( is bigger better?) and how much air should pass thru for cooling it?, the cooling fan seems necessary!! how did you cover the top of the bonnet after making a cut for the airflow.

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fascar

Yes a bigger cooler is better for cooling surface area and to not restrict turbo air flow, but too big will increase lag as the turbo is slower to get the whole volume up to boost.

 

A large flat cooler is ideal if it fits. Mine is a dual thickness core and was a bit thicker than I would have liked so clearance is a problem to fit over the motor and fit a fan under the bonnet. It was good quality, high flow and cheap so I can't complain.

 

 

The bonnet (hood) scoop is from a Nissan Patrol GU.

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The scoop has a little lip on the underside that directs the air down at the back. I have made an aluminium surround for the intercooler which has a rubber seal that fits up close to the bonnet just behind the back lip on the scoop when the bonnet is closed. You could get the genuine Nissan Patrol rubber surround for the 3L TD motor but it needed extra clearance to fit between the scoop and top of the intercooler, OK if you do a 2 or 3" body lift but mine has no body lift at all. The fan is a real tight fit up into the scoop so I have cut slots in the front of the fan shroud to let air in.

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The Intercooler was from a race BMW and was mounted at the front side ways hence the two round bits that stick out the side they sat in rubber bushes.

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It just happened to fit exactly between the turbo and inlet, I just welded it straight to the flange at one end and to a pipe adapter at the turbo end. It was so solid on the end tank that I have not fitted a support bracket, now done 150,000 km since fitted with no problems.

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It was a very tight fit around the pressure blow-off valve on the inlet manifold so I had to file down a bit.

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Also fitted a front thermo fan, which needed the grille to be modified for extra room.

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Also an oil cooler for the gearbox.

oilcooler10216bw1.th.jpg

 

I don't know much about intercoolers for mitsubishi or toyota except that if you can find one with the pipes from the end tank both pointing in the correct direction, it will help.

 

If you do a lot of slow driving in sand on hot days the fan is a must. You could also look at a heat shield over the exhaust to reduce hot air and radiation heat from coming up to the intercooler. The best intercooler to prevent this is an air to water (coolant) type but a lot more expensive ($2000 Australian) see: link in earlier post.

 

 

I hope this information helps.

 

Let us know how you are going with the project.

 

Geordie

Edited by geordie4x4
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Guest fascar

Geordie4x4,

 

Thanks abundle mate, I promise to keep u updated on the project. I am a bit allergic to the digital revolution so the pic thing might not be that prompt.

 

Fascar

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