TD27T Needs more bottom end GRUNT

Hi Fellas

Went bush in the Terrano this past weekend and found it very sluggish under 2500 rpm. Anything remotely steep had to be attacked in low 1st and I very steep section was almost too much for the poor little thing.

I have decided I can do 3 things to help this, and would like peoples opinions on which should be first, or is best bang for my buck, or maybee one is not worth doing without another. Or maybe I have overlooked a better option (no Im not stuffing a gen III in it)...

1. Snorkel
2. Top mount Intercooler, as I have one
3. Exhaust

What order, What else, Whatever ????

Ps.. Currently running 31's and 4.65 gears. Soon changing to 33"s and 4.88 gears giving almost the same final ratios as I am at now...

Haha welcome to the crappy td27 engine.

I popped a TMIC on mine. It doesn't help bottom end power, since there's no good airflow to help the IC, but it does pick up A LOT on straights when you need it. Best 50$ mod I ever did.

I'd go with ensuring for one, the turbo isn't busted (mine is). Change your fuel filters, air filter, maybe try some injector cleaner stuff if your engine is a bit old and clean the injector pump screw filter thingy that stuffs everyone's td27's up and makes it super sluggy. Maybe that'll be a place to start?

I have actually started to consider getting a chip for my td27 though, hoping that will give it a bit more go?

Exhaust might help. If we look at our exhaust manifold it's a very poor, inefficient design. I wouldn't mind getting a decent after market one (if they exist) and swap around to that, plus then get 2.5 straight through.

D21 dualcab Z24 4X4 said:

Went bush in the Terrano this past weekend and found it very sluggish under 2500 rpm. Anything remotely steep had to be attacked in low 1st and I very steep section was almost too much for the poor little thing.

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Something must be broken. One of the few good things about these motors (high-compression low-boost) is that they are unstoppable all the way from idle, soooo much torque.

D21 dualcab Z24 4X4 said:

I have decided I can do 3 things to help this, and would like peoples opinions on which should be first, or is best bang for my buck, or maybee one is not worth doing without another. Or maybe I have overlooked a better option (no Im not stuffing a gen III in it)...

1. Snorkel

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If the problem's not in water, then rule this out.

D21 dualcab Z24 4X4 said:

2. Top mount Intercooler, as I have one

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Like Tatty said, won't help hugely.

D21 dualcab Z24 4X4 said:

3. Exhaust

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Might help a bit but as I said it sounds like something is sick.

D21 dualcab Z24 4X4 said:

Ps.. Currently running 31's and 4.65 gears. Soon changing to 33"s and 4.88 gears giving almost the same final ratios as I am at now...

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4.88s and 29"s, I do most 4x4 in high range, I only make it into low first on the really gnarly stuff. Low first idling you can walk along next to it.

tatty said:

clean the injector pump screw filter thingy that stuffs everyone's td27's up and makes it super sluggy. Maybe that'll be a place to start?

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Banjo filter. Good advice. Not all were fitted with it though so don't be surprised if it isn't there.

tatty said:

I have actually started to consider getting a chip for my td27 though, hoping that will give it a bit more go?

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Can't chip a mech injection engine, you can get the fuelling cranked up though. Same concept.

tatty said:

Exhaust might help. If we look at our exhaust manifold it's a very poor, inefficient design. I wouldn't mind getting a decent after market one (if they exist) and swap around to that, plus then get 2.5 straight through.

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No aftermarket manifolds, well there are but they're not that different from the factory one. Not much advantage chasing higher flows pre turbo.

It has performed about the same for the last 12 months or so since we bought it. Just had the injector pump rebuilt. Uses maybee 1 litre of oil between oil changes.

Maybe I should start with the basics and do a compression test ?

Dion said:

If the problem's not in water, then rule this out.

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I think he was aiming more for a 'cold air intake' concept. But still, at low speed it doesn't matter.

Banjo filter. Good advice. Not all were fitted with it though so don't be surprised if it isn't there.

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Which one's didn't have it fitted? I presumed all the Terranos/Pathfinders had it.

No aftermarket manifolds, well there are but they're not that different from the factory one. Not much advantage chasing higher flows pre turbo.

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Well the pressure the manifold puts onto the turbo is extremely uneven when you look at it's design. I guess this is just the petrolhead inside of me thinking chasing those last few killawasps.

Know much about buggered fuel consumption? I was under the impression I should be getting around 8l/100k, not the 13-14l/100 I'm on at the moment.

tatty said:

I think he was aiming more for a 'cold air intake' concept. But still, at low speed it doesn't matter.

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I know. I just don't believe in the snorkel = CAI thing.

tatty said:

Which one's didn't have it fitted? I presumed all the Terranos/Pathfinders had it.

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I think it was a recall/TSB kind of thing. So if the vehicle was within the right manufacture date range, and the dealer didn't respond to the TSB or if the vehicle was non-dealer serviced, it won't have it.

tatty said:

Well the pressure the manifold puts onto the turbo is extremely uneven when you look at it's design. I guess this is just the petrolhead inside of me thinking chasing those last few killawasps.

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There wouldn't even be a kilowatt improvement in it.

tatty said:

Know much about buggered fuel consumption? I was under the impression I should be getting around 8l/100k, not the 13-14l/100 I'm on at the moment.

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8L/100 in an auto is optimistic. 10L/100 with a manual is good to normal. 13-14 just indicates auto trans with perhaps some very minor over-consumption.

Dion said:

8L/100 in an auto is optimistic. 10L/100 with a manual is good to normal. 13-14 just indicates auto trans with perhaps some very minor over-consumption.

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I get around 11L/100 regularly...

did this to mine lots of grunt

passenger pete said:

did this to mine lots of grunt

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What is it off exactly.. Looks damn neat

its of a subaru rs legiacy 89-93. I also changed dump pipe too and exhaust. The td27t is a great we motor super strong.

passenger pete said:

its of a subaru rs legiacy 89-93 i changed dump pipe to the td27t is a great we motor super strong.
http://img594.imageshack.us/img594/2483/img9623r.jpg

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Did you fit the turbo or just the intercooler from the Legacy ?

just the water to air intercooler from the legacy, feels better then the top mounted rx7 air to air i did have on. have not done back to back testing tho

I know you said you had the pump rebuilt, but did you have the pump timing checked? This can be a source of lost power whilst everything else seems ok.

I've been in an auto Terrano TD27T that would spin the wheels with a good stab of the throttle off the line, so yours doesn't sound quite right somehow.

My guesses would be:
Pump timing
Blocked fuel line
Some kind of intake leak between turbo and intake manifold


You can see below here that it makes it's peak torque at 2200rpm either engine you have (Terrano 1 or Terrano 2)

TD27T2

100 PS (73.5 kW; 98.6 bhp) @ 4000 RPM
22.0 kg·m (216 N·m; 159 lb·ft) @ 2200 RPM

Nissan Terrano and Datsun Truck series D21 from 1988 to 1996


TD27T4

115 PS (84.6 kW; 113.4 bhp) @ 4000 RPM
24.8 kg·m (243 N·m; 179 lb·ft) @ 2200 RPM

Nissan Terrano series D21 from 1994 to 1995

The only thing stopping you climbing a hill should be traction, not the engine.

anyone thought about the front mount option ? . . .

xr6 turbo factory and some after market options fit behind the bullbar of mine with relatively simple pipe work , . . . add a water spray or mount a thermo if your doing lots of slow off road work . . .

from an air intake charge density point of view the cooler the air the more dense and also there is a thermal reduction effect too ( minimal ) . the problem with top mount is heat soak and the problem with water to air is that the air will never be cooled less than the temp of the coolant of the engine unless you run a stand alone system , but that's quite costly . . .

Im just wondering why i have not seen or heard of it done on a d21? . . .

i decided my upcoming project will have front mount but my majority of driving is highway or earth works / road works job sites , and the odd weekend play few and far between shooting with the boys .

dion your right up with the d21 why does no one appear or that i know of go front mount when its the most logical choice . . . even going slow the draw of the fan has a cooling effect , because lets not forget that an intercooler does not actually cool the air charge its more a heatsink that scrubs heat out of the charge the turbo inherently creates through producing boost .

this may be a stupid ramble but the science is there so i see no reason not to tig up the piping and run a front mount behind the bar . . .

fst_38 said:

anyone thought about the front mount option ? . . .

xr6 turbo factory and some after market options fit behind the bullbar of mine with relatively simple pipe work , . . . add a water spray or mount a thermo if your doing lots of slow off road work . . .

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A bunch of D22 owners have done just that. Depends a lot on your bullbar; if you've ever looked between the front grille and radiator of a D22 there's a bunch of space; look in the same spot on the D21 and there's barely any. It's all to do with frontal impact attenuation, anyway the point is you'd have to have a winch bar or a bar which leaves you heaps of space, but doesn't block the airflow to the intercooler.

fst_38 said:

from an air intake charge density point of view the cooler the air the more dense and also there is a thermal reduction effect too ( minimal ) . the problem with top mount is heat soak and the problem with water to air is that the air will never be cooled less than the temp of the coolant of the engine unless you run a stand alone system , but that's quite costly . . .

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I have never seen a W2A run off the existing cooling system and I hope to never see one set up that way.

fst_38 said:

Im just wondering why i have not seen or heard of it done on a d21? . . .

dion your right up with the d21 why does no one appear or that i know of go front mount when its the most logical choice . . . even going slow the draw of the fan has a cooling effect , because lets not forget that an intercooler does not actually cool the air charge its more a heatsink that scrubs heat out of the charge the turbo inherently creates through producing boost .

this may be a stupid ramble but the science is there so i see no reason not to tig up the piping and run a front mount behind the bar . . .

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Nothing wrong with it, it's just that there are a limited number of D21s that have been converted to turbo, and of that small pool, a limited number which have gone to the effort of fitting an intercooler, and of that even smaller pool, there just hasn't been anyone willing to make the extra effort for a FMIC over a TMIC. The only negative to a FMIC (since turbo lag is not a concern on these slow old engines) is the potential for your pipework to be exposed to 4x4ing damage at the front of the vehicle. That all comes down to how much effort you put into tucking it up out of harm's way though.

Your point is valid about the intercooler just buffering charge air temp between on boost and off boost steady states, however one difference which sets these diesels apart from the turbo petrol monsters you're well experienced with is the duration spent at full boost - the petrol cars reach full boost in small spikes during acceleration (dependent on setup obviously), these diesels intentionally sit at full boost steady state whilst cruising on the freeway. So your intercooler needs to be more effective at steady state heat removal than an equivalent petrol application where it is a buffer first and a heat sink second. Something to consider when designing.

Dion said:

I have never seen a W2A run off the existing cooling system and I hope to never see one

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quite a common mistake i see done and when it rolled onto the hoist like that it began to cost big dollars . its a common mistake performance noobs make

i plan to run something 300x200x65 with my own end tanks . piping will duck on the outside edges under the radiator behind the bash plate . so i would hope i don't damage it through 5mm mild ! . ill cut slots into my bar and weld an 8 mm mild silhouette plate in . . . maintain integrity and have quite a large potential air flow to the cooler .

i will have long piping , Im not too worried about associated pressure drop as you have said , thanks mate , heat soak has entered my mind due to underbonnet temps but a lesson i learned from my Evo 8 race car is to wrap the whole cold side pipe to prevent heat soak as much as possible .

Im keen for it hey . ill do some baselines no FMIC and fitted FMIC .

i guess the thing too is i don't do extreme off road tracks and shit just work sites , camping and out the farm shooting . i have a higher chance of clouting skippy than staking it !

I enjoy reading all these post but all I can see is $$$$$$$. The car is worth 3k maybe... To get somebody to fab up the parts required to fit a TMIC or FMIC and Bla Bla etc, All just to end up with an OK performance, I may as well just buy a cheap d22

Same outlay and same performance with no mucking around..

I dunno, just a little shy about over capitalising.

D21 dualcab Z24 4X4 said:

I enjoy reading all these post but all I can see is $$$$$$$. The car is worth 3k maybe... To get somebody to fab up the parts required to fit a TMIC or FMIC and Bla Bla etc, All just to end up with an OK performance, I may as well just buy a cheap d22

Same outlay and same performance with no mucking around..

I dunno, just a little shy about over capitalising.

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Td27T are pretty cheap these days... mine ended up costing me nothing, once i sold parts from the wreck..the TMIC setup i put on was no more than $300...best money ever spent on the navara.

of cause thats with doing all the workmyself.

Ill be changing the turbo and making a full exhaust in the coming months, but this wont cost to much.