a few Q's regarding a 1.8T

[Datsun]

The other half has a 2003 1.8T I'm going to convince her it needs a re-map done to improve performance/economy

now I'm lead to believe that anything up to 180bhp is achievable from a map.


This then leads me on to the next question, I have a spare 2871r laying around, I'm sure I have seen the odd A3 using these units but I'm unsure of who good they are on this engine.
without going massively overboard, what sort of pressures/power can the std engine take before metal HG's are required, or indeed forged internals?

and the Standard IC at what power do they become inefficient?

 

[16Klappe]

Wouldn't bother.

A 2003 1.8t will have a Ko3s, which with a decat and downpipe, silicone turbo intake pipe, an air filter and a Forge 007P will map to 225/230bhp if you haven't got any boost leaks.

Standard intercooler will run at 225BHP fine on the road in daily conditions, but it's when you get it on a RR or on a warm day it will start to suffer. I have a front mount, but remember a front mount will also mean more lag which isn't great for a daily driver. You'll also have to lose the foglights unless you are handy with a file and tubes!

As with anything it's all about the mapping, a lot of people run GT28's on Mk4's with standard internals. A big turbo running at a lower PSI is much safer than a tiny turbo running at a high PSI. As long as it is mapped to come in about 4K it'll be fine without even taking the head off.

 

[Datsun]

thats why i want to use this 2871 it should certainly spool well before 4k

when you say GT28's are you talking just about a generic journal T28 or a roller bearing unit?

Wouldn't bother.

A 2003 1.8t will have a Ko3s, which with a decat and downpipe, silicone turbo intake pipe, an air filter and a Forge 007P will map to 225/230bhp if you haven't got any boost leaks.

Standard intercooler will run at 225BHP fine on the road in daily conditions, but it's when you get it on a RR or on a warm day it will start to suffer. I have a front mount, but remember a front mount will also mean more lag which isn't great for a daily driver. You'll also have to lose the foglights unless you are handy with a file and tubes!

As with anything it's all about the mapping, a lot of people run GT28's on Mk4's with standard internals. A big turbo running at a lower PSI is much safer than a tiny turbo running at a high PSI. As long as it is mapped to come in about 4K it'll be fine without even taking the head off.

 

[Broken Byzan]

the GT28 should spool by 3k tops. It's all about the mapping and torque with an element of luck thrown in too.


It used to be around 300/300 as a safe limit, but as these cars age fatigue sets in and becomes a factor...

 

[16Klappe]

The whole point of it spooling up higher in the rev range is so you can run it on stock internals, the engine has already done the hard work of spinning up by the time it gets full boost which = much safer on the rods. I would be comfortable running a GT28 and having full boost at 4K.

Having a GT28 on full boost at 3K WOULD **** it up within months IMO, I know 1000RPM isn't much but 4K would give a fair amount of safety where as 3K IMO would be touch and go.

Torque is the main 'rod killer, and having it low down is a double dose of engine death. My own car will make 26/28PSI at 2.5K if I just give it full throttle, but all it does then is run lean and misfire because the boost is far too high and snuffs out the spark. I'm pretty sure if it didn't misfire and kill the boost back down it would have bent a rod by now or the turbo would start eating itself.

As far as I'm aware anybody who buys the cheaper journal bearing GT28 is a muppet when the 360 bearing is pretty much no more expensive. I wasn't aware anybody even sold the journal bearing GT's anymore? Having said that I know **** all about anything so don't listen to me.

Have a look at all of these GT series turbo'd 1.8t videos, and notice none of them get full boost/higher than 20psi lower than 4K -

 

[Datsun]

umm, i think you may have your wires crossed, a journal bearing comes in two forms, either a 270 degree or a 360 degree bearing...but the amount t the same thing...journal bearings.

the GT28 everyone refers to is also a sweeping statement, which GT28 series are people referring to?

the GT2871r I might use is a GT28 but that said a GT2560r is also a GT28 series...but are completely different animals

Bad mapping is what causes damaged engines not high boost as for wanting later spool up to protect engine, not entirely sure thats the case, higher up rev range the engine will be under greater load..potentially increasing the likelihood of engine damage, less lag means changing gear sooner (peak power lower in rev range) meaning internal temps are kept lower, 4k does seem really really late to me, would sooner have an engine producing lower down torque than an engine you have to wring its neck right up to the rev limit to get it to perform.

The whole point of it spooling up higher in the rev range is so you can run it on stock internals, the engine has already done the hard work of spinning up by the time it gets full boost which = much safer on the rods. I would be comfortable running a GT28 and having full boost at 4K.

Having a GT28 on full boost at 3K WOULD **** it up within months IMO, I know 1000RPM isn't much but 4K would give a fair amount of safety where as 3K IMO would be touch and go.

Torque is the main 'rod killer, and having it low down is a double dose of engine death. My own car will make 26/28PSI at 2.5K if I just give it full throttle, but all it does then is run lean and misfire because the boost is far too high and snuffs out the spark. I'm pretty sure if it didn't misfire and kill the boost back down it would have bent a rod by now or the turbo would start eating itself.

As far as I'm aware anybody who buys the cheaper journal bearing GT28 is a muppet when the 360 bearing is pretty much no more expensive. I wasn't aware anybody even sold the journal bearing GT's anymore? Having said that I know **** all about anything so don't listen to me.

Have a look at all of these GT series turbo'd 1.8t videos, and notice none of them get full boost/higher than 20psi lower than 4K -

 

[Broken Byzan]

The whole point of it spooling up higher in the rev range is so you can run it on stock internals, the engine has already done the hard work of spinning up by the time it gets full boost which = much safer on the rods. I would be comfortable running a GT28 and having full boost at 4K.

Having a GT28 on full boost at 3K WOULD **** it up within months IMO, I know 1000RPM isn't much but 4K would give a fair amount of safety where as 3K IMO would be touch and go.

Torque is the main 'rod killer, and having it low down is a double dose of engine death. My own car will make 26/28PSI at 2.5K if I just give it full throttle, but all it does then is run lean and misfire because the boost is far too high and snuffs out the spark. I'm pretty sure if it didn't misfire and kill the boost back down it would have bent a rod by now or the turbo would start eating itself.

As far as I'm aware anybody who buys the cheaper journal bearing GT28 is a muppet when the 360 bearing is pretty much no more expensive. I wasn't aware anybody even sold the journal bearing GT's anymore? Having said that I know **** all about anything so don't listen to me.

Have a look at all of these GT series turbo'd 1.8t videos, and notice none of them get full boost/higher than 20psi lower than 4K -

So you know all of these are on standard internals?

Also the OP stated GT2871r which is a specific unit not a GT 28 based unit, and should be roller bearing'd iirc.

Also if you cannot go full throttle without misfire, i'd go back to your tuner and ask him to finish the job, lean under load is wrong.

My GTRS turbo had better spool up before 4000 revs or i'll be throwing it down the road.

PS i am also aware it's torque that kills rods BTW.

 

[Broken Byzan]

Bad mapping is what causes damaged engines not high boost as for wanting later spool up to protect engine, not entirely sure thats the case, higher up rev range the engine will be under greater load..potentially increasing the likelihood of engine damage, less lag means changing gear sooner (peak power lower in rev range) meaning internal temps are kept lower, 4k does seem really really late to me, would sooner have an engine producing lower down torque than an engine you have to wring its neck right up to the rev limit to get it to perform.

The point is the lower down the revs you drive the car the more torque your inevitably producing. The rods in these engines are the weak point, and its torque that kills them.

As a result hitting massive boost at 2.5-3k will mean a large and hence dangerous torque spike. At 6000rpm your producing more power but typically a lot less torque, which is inherently safer.

That said, you can have the turbo spooling as early as it can, so long as the boost is controlled to keep the torque to a safe level. So your right in that its all in the mapping.

 

[Datsun]

The GTRS (GT2860R) should give full boost by 3k at absolute most, it certainly does on the SR20 so your car shoudl be certainly a lot of fun.

as for GT2871r yeah its a roller bearing unit (like yours, although i believe the 2871 is a dual roller bearing)

I too was going to mention about the blokes car missing on full throttle, but thought better of it seeing as I'm a newb lol but you are absolutely right, go back and get it sorted and drive of boost until that point, you "blowing spark out" would worry me intensely.

my first Turbocharged car (years and years ago) was running circa 28psi and it loved it never misfired, spluttered nothing because the mapping was so damned tight on it, i assume you are running much colder plugs? sounds like the misfiring could be the ignition retarding to cope with the load you are putting the engine under

So you know all of these are on standard internals?

Also the OP stated GT2871r which is a specific unit not a GT 28 based unit, and should be roller bearing'd iirc.

Also if you cannot go full throttle without misfire, i'd go back to your tuner and ask him to finish the job, lean under load is wrong.

My GTRS turbo had better spool up before 4000 revs or i'll be throwing it down the road.

PS i am also aware it's torque that kills rods BTW.

 

[<tuffty/>]

...Having said that I know **** all about anything so don't listen to me...

Amen brother (love yah Jardo;P)

Righty... lets clear a couple of things up...
Yes you still can get Journal bearing GT's (Garrett GT Journal Bearing : atpturbo.com)

Journal bearing refers to the bearing the shaft runs in, the 270/360 bearing is the thrust bearing

GT2871r is ball bearing and will on it before 3.5k (GT28s and GT2860's spool earlier)

All 1.8t's come with metal head gaskets... high hp engine (500+ typically) are known to lift the head on std head bolts so ARP's are recommended (won't see that on a GT2871r)

A 2003 1.8t will have 19mm rods so if you go GT2871r then change them...

Valve train is the only other weak point but generally this is due to worn exhaust guides that promote valve float are the higher rpm's associated with bigger turbo conversions... GT2871r should be fine though with a sensible rev limit and maybe the guides replaced while the heads off doing the rods...

Mapping is key of course and torque is the main rod killer but all this nonsense about a GT28 on full boost etc... jeez... at 28psi the K03 in Jardos car currently hasn't long to live... a properly mapped GT2871r will do 24/26psi all day long with supporting mods and outlast a K03 thats flat out... I have sen more than enough tired K03's in my time...

In answer to the OP original questions...
As Jardo has already said the K03s will do best part of 230hp with the right supporting mods... these should include a FMIC imo as this will give that power more than once... with the std SMIC you may achieve it once then it will just get too hot and you will loose power until its all cooled down again...

The GT2871r is a different thing altogether... this will require alot more mods... rods, new injectors, S3 MAF housing, custom intake, custom downpipe, decent FMIC, custom mapping, T25 exhaust manifold etc... a decent GT2871r setup will net you between 350/370hp depending on how far you go...

As the car is not yours I would suggest a remap and be happy... you will see 210/220hp with conservative boost etc

<tuffty/>

 

[16Klappe]

The way I see it is if you want the power of a GT series turbo down low then you need rods, if you want the power of a GT turbo and don't want rods you need the torque and boost to come in higher up for it to stand a chance at being safe. Simples in my eyes.

I'll butt out seeing as you guys know so much about them, have a read of this thread which is posted in the FAQ's for a bit more information. It is very American orientated though -

http://www.audi-sport.net/vb/a3-s3-forum-8l-chassis/75685-lots-big-turbo-high-power-info.html

*edit*, Paul to the rescue! The lord of all GT builds!!!

 

[Datsun]

cheers mate

i was asking specifically about the 2871 simply because i have a spare one here, it seems its a fair amount of work to get it run, so maybe ill stick to just a remap and keep mine as a spare

ta for info

Amen brother (love yah Jardo;P)

Righty... lets clear a couple of things up...
Yes you still can get Journal bearing GT's (Garrett GT Journal Bearing : atpturbo.com)

Journal bearing refers to the bearing the shaft runs in, the 270/360 bearing is the thrust bearing

GT2871r is ball bearing and will on it before 3.5k (GT28s and GT2860's spool earlier)

All 1.8t's come with metal head gaskets... high hp engine (500+ typically) are known to lift the head on std head bolts so ARP's are recommended (won't see that on a GT2871r)

A 2003 1.8t will have 19mm rods so if you go GT2871r then change them...

Valve train is the only other weak point but generally this is due to worn exhaust guides that promote valve float are the higher rpm's associated with bigger turbo conversions... GT2871r should be fine though with a sensible rev limit and maybe the guides replaced while the heads off doing the rods...

Mapping is key of course and torque is the main rod killer but all this nonsense about a GT28 on full boost etc... jeez... at 28psi the K03 in Jardos car currently hasn't long to live... a properly mapped GT2871r will do 24/26psi all day long with supporting mods and outlast a K03 thats flat out... I have sen more than enough tired K03's in my time...

In answer to the OP original questions...
As Jardo has already said the K03s will do best part of 230hp with the right supporting mods... these should include a FMIC imo as this will give that power more than once... with the std SMIC you may achieve it once then it will just get too hot and you will loose power until its all cooled down again...

The GT2871r is a different thing altogether... this will require alot more mods... rods, new injectors, S3 MAF housing, custom intake, custom downpipe, decent FMIC, custom mapping, T25 exhaust manifold etc... a decent GT2871r setup will net you between 350/370hp depending on how far you go...

As the car is not yours I would suggest a remap and be happy... you will see 210/220hp with conservative boost etc

<tuffty/>

 

[16Klappe]

I too was going to mention about the blokes car missing on full throttle, but thought better of it seeing as I'm a newb lol but you are absolutely right, go back and get it sorted and drive of boost until that point, you "blowing spark out" would worry me intensely.

my first Turbocharged car (years and years ago) was running circa 28psi and it loved it never misfired, spluttered nothing because the mapping was so damned tight on it, i assume you are running much colder plugs? sounds like the misfiring could be the ignition retarding to cope with the load you are putting the engine under

No feel free to mention it haha, without sounding like the massive self righteous bender that I am being told that the mapping is wrong on my car has literally made me laugh out loud.

Nothing wrong with the mapping on my car buddy, it's the £30 MAF that I can't be ***** to replace that does it.

 

[Datsun]

no i haven't mate, to be honest I've not really looked around the forum

do you have a link?

No feel free to mention it haha, have you seen my car? :thumbsup:

 

[16Klappe]

no i haven't mate, to be honest I've not really looked around the forum

do you have a link?

Have a look at my edit below for a very traction limited video , I always have to re-edit my posts because I come across as a massive bender and a bit of a willy. When in reality I am actually quite nice (I hope lol!)

My car is 240bhp on a good day, probably one of the fastest Ko3s 1.8t's about (again, without sounding like a bender)

I'm assuming you haven't got an A3 then? What do you drive, certainly know your beans by the looks of it!

 

[Datsun]

My gf has just bought the Audi, i own an S14a Nissan 200SX, had it about 7years

Have a look at my edit below for a very traction limited video , I always have to re-edit my posts because I come across as a massive bender and a bit of a willy. When in reality I am actually quite nice (I hope lol!)

My car is 240bhp on a good day, probably one of the fastest Ko3s 1.8t's about (again, without sounding like a bender)

I'm assuming you haven't got an A3 then? What do you drive, certainly know your beans by the looks of it!

 

[Prawn]

what a comedy thread this is

Sadly matey, getting decent power out of the 1.8T isn't quite so easy as it is from the SR20's you're used to, simply because, not so many people do it!

The 2871 You have COULD be made to fit a Paul has said, but the reality is, you'd be looking at £2.5k by the time you've got it fitted, with all the required hardware, and mapped up, more like £3500 if you include rods into the equation too!

Being a 2003, your 1.8T will be an AUM engine with the better ko3S.

with no mods at all, a stage 1 map on this should net you 205-210bhp, with 220-230lbft roughly.

Add in a 3'' DP/decat from ebay for £120, and that opens things up a huge deal, coupled with a decent airfilter, and a forge 007P recirc valve as a precautionary, and you should see 220-225bhp, my AUM with a stage 1 map and 3'' DP/decat makes 224bhp / 260lbft, on the standard SMIC, and it goes really well.

Truth is, on track it heatsoaks in no time, as the SMIC can't cope with more than a few hard pulls, but for road use, it's perfectly fine, and motors along nicely.

For a daily driver, an AUM, with a downpipe and st1 map really is plenty, and will be rewardingly rapid. More than enough to show up all standard/most st1 S3's

 

[Datsun]

cheers mate, i was surprised when it was mentioned that rods..well potentially an engine rebuild of some description was almost a must when fitting what i would consider a mild turbo.

perhaps you are right I may be spoilt with the SR.

but many thanks for everyone's contributions to this thread

what a comedy thread this is

Sadly matey, getting decent power out of the 1.8T isn't quite so easy as it is from the SR20's you're used to, simply because, not so many people do it!

The 2871 You have COULD be made to fit a Paul has said, but the reality is, you'd be looking at £2.5k by the time you've got it fitted, with all the required hardware, and mapped up, more like £3500 if you include rods into the equation too!

Being a 2003, your 1.8T will be an AUM engine with the better ko3S.

with no mods at all, a stage 1 map on this should net you 205-210bhp, with 220-230lbft roughly.

Add in a 3'' DP/decat from ebay for £120, and that opens things up a huge deal, coupled with a decent airfilter, and a forge 007P recirc valve as a precautionary, and you should see 220-225bhp, my AUM with a stage 1 map and 3'' DP/decat makes 224bhp / 260lbft, on the standard SMIC, and it goes really well.

Truth is, on track it heatsoaks in no time, as the SMIC can't cope with more than a few hard pulls, but for road use, it's perfectly fine, and motors along nicely.

For a daily driver, an AUM, with a downpipe and st1 map really is plenty, and will be rewardingly rapid. More than enough to show up all standard/most st1 S3's