Hey guys I am thinkin of building a mk3 polo gt turbo, i was going to get a 1.4 golf bottom end(ABD) but am un sure if i would be better using a gt head or the 1.4 head, bearing in mind it will be getting ported polished etc, i have been told a passat turbo will do the job, how easy is this going to be and what extra parts will i need to complete the project. i suppose one of the most important things is how much BHP will i roughly get if i do this conversion. cheers.

No, the most important thing is getting the compression and fuelling right. Have you worked out what compression you're going to need? No offence to you at all, but when someone comes on here asking "how easy is this going to be" with regards to a turbo conversion, you shouldn't be doing it. But here we go:

Spacer plate at the very least to lower the compression, custom pistons are a better idea. The standard rods aren't likely to be up to much either.

Turbo exhaust manifold

The GT throttle body should be alright to boost through, if not you'll want a G40 throttle body (and probably G40 or G60 injectors for that matter)

Custom ECU mapping at the least, ideally standalone ECU (hours of rolling road sessions needed to set up)

New cam profile (the GT cam will start you off alright though I'd have thought)

All turbo pipework etc

And depending on power output, you probably won't want to be using the standard GT brakes or suspension either.

The easiest way of doing it would be to get an entire G40 lump excluding the charger, get a manifold made up and get a turbo ECU map if you can get it. Starting with an ABD when there is a low compression engine already available is a false economy. How much is your budget?

Edited 17 June, 200719 yr by tobyk

hey mate, i take no offence you prob know a lot more than me, at least you are being honest, i suppose as i am not planning on how much i spend just see how it goes really.

as you seem to know what you are talking about i should ask i want to get as much power as possible what is the best way to go about this if the turbo is not such a good idea. thanks a lot.

Ryan

I'm still learning, but that's the things I'd think you'd need to do. If you can source a G40 bottom end, work from there. As they are lower compression already, you won't need anything custom made. There are a couple of turbo'd G40s on the forum, maybe look through the members gallery and ask the owner for more info.

bolting a turbo on is a surefire way of getting big power, but unless you want it to go bang you will need lots of other bits, low CR pistons for one as you cant add boost to the gt as it already has a CR of 10:1

the rods on the earlier 1.3s are good but the later engines are crappy chocolate ones.

you will need either a boost controller with 5th injector or G40 management.

you will be able to get away with the GT cam to start but wont be ideal as the exhaust duration will be a bit long..

Edited 18 June, 200719 yr by currie

Pretty sure GT engines are 10:1 compression ratio

As am I...

and me, sorry curry......lol

berg cup cars run something like 13:1 tho!

no offence, do a search... this gets asked about once a week

No offense,but.. :) what are you trying to achieve? I'll be honest - you dont know what you're doing and you're going to pay alot of money,and spend alot of time messing about,building something that's going to break real fast - by the sound of it so far. Why do you want to polish and port the head? Little point without serious boost pressures - turbo cylinder heads are rubbish standard jobs. They dont need flowed ports as the air is under pressure anyway. Putting carbs on a turbo engine doesnt get good results because of this,so you're clearly misguided on the basics. If you dont get it set up properly,even 130bhp is gonna blow holes in pistons. You ask about outright power,but turbo's dont rev freely or have much low torque. I'm using a free-revving circa 120+bhp 1.6 and in the real world its flexibility means it'd probably hold a 150bhp 1.4 turbo,which only has that power in a narrow power-band at high revs. If you're building a Santa Pod runner,you'd better start concentrating on strengthening issues. Not just the engine internals,but uprated driveshafts,gearbox,final drive etc etc.

Pretty sure GT engines are 10:1 compression ratio

As am I...

and me, sorry curry......lol

No idea what you are all on about :paranoid: :paranoid:

but turbo's dont rev freely or have much low torque

Erm... riiight.

No offense,but.. :) what are you trying to achieve? I'll be honest - you dont know what you're doing and you're going to pay alot of money,and spend alot of time messing about,building something that's going to break real fast - by the sound of it so far. Why do you want to polish and port the head? Little point without serious boost pressures - turbo cylinder heads are rubbish standard jobs. They dont need flowed ports as the air is under pressure anyway. Putting carbs on a turbo engine doesnt get good results because of this,so you're clearly misguided on the basics. If you dont get it set up properly,even 130bhp is gonna blow holes in pistons. You ask about outright power,but turbo's dont rev freely or have much low torque. I'm using a free-revving circa 120+bhp 1.6 and in the real world its flexibility means it'd probably hold a 150bhp 1.4 turbo,which only has that power in a narrow power-band at high revs. If you're building a Santa Pod runner,you'd better start concentrating on strengthening issues. Not just the engine internals,but uprated driveshafts,gearbox,final drive etc etc.

yea, turbos are shit

My mates 2 litre rover only gives 375 lb/ft of torque at 4000rpm

and only revs to 7500rpm

really shows how shit turbo cars are

he is going to take the turbo off and fit bike carbs, so he can get more talk

MIkey why does nearly every post you make revolve around the fact that youve managed to get 120bhp out of a 1.6 and thus imply that everyone should follow suit?

Top marks for having a quick mk2, we appreciate that fact, but I've heard a lot about yours now so i probably don't need to be refreshed again. You seem like a decent fella but my god you do chat some utter bull sometimes.

Touch the throttle in my dad's supra (rather large turbo) and it picks up proper quick, the time it takes you to put your foot to the floor and back off again(rather considerable pedal travel) is enough for it to hit the limiter when in neutral. But it does suffer from serious turbo lag, doesn't really pick up till 3500 or so.

My mum's Volvo on the other hand has a quite small turbo, and although not as eager to rev as the Supra will pull from idle better than most things, plant your foot while ticking over in gear and it's huge turbo whistle (de-baffled airbox, k&n, wastegate shimmed) and it pulls hard with the wheels spinning to about 4000 (where the supra is just picking up) and stays pretty flat from there. Do the same in second, ticking over, foot to the floor and it does exactly the same, spins the wheels up till about 4000. It will rev to 6750, but won't be making any torque above 4k or so.

So basically, turbo choice is probably the most important decision you can make.

No offense,but.. :) what are you trying to achieve? I'll be honest - you dont know what you're doing and you're going to pay alot of money,and spend alot of time messing about,building something that's going to break real fast - by the sound of it so far. Why do you want to polish and port the head? Little point without serious boost pressures - turbo cylinder heads are rubbish standard jobs. They dont need flowed ports as the air is under pressure anyway. Putting carbs on a turbo engine doesnt get good results because of this,so you're clearly misguided on the basics. If you dont get it set up properly,even 130bhp is gonna blow holes in pistons. You ask about outright power,but turbo's dont rev freely or have much low torque. I'm using a free-revving circa 120+bhp 1.6 and in the real world its flexibility means it'd probably hold a 150bhp 1.4 turbo,which only has that power in a narrow power-band at high revs. If you're building a Santa Pod runner,you'd better start concentrating on strengthening issues. Not just the engine internals,but uprated driveshafts,gearbox,final drive etc etc.

Re-working a cylinder head, whether forced induction or not, generally yields worthwhile gains. This "air is under pressure anyway" malarky is utter tripe. Take two identical balloons and blow them up to the same size. They're then roughly holding the same amount of air, at the same pressure. Pop one - notice it goes down immediately, you've released the pressurised air through a massive surface area. Compare that to letting one down through the neck of the balloon, which takes several seconds.

Similar thing with forced induction, bigger ports and valves allow you to force more air into the cylinder. There's obviously an optimum size for each application though, that's a complicated function of gas speeds; compressor efficiency; port shape; cam choice; exhaust sizing etc. etc.

You can have very free revving turbos, and also turbos making plenty of low-down torque. Achieving both at the same time to the extreme is almost impossible, but the same is true of a naturally aspirated motor. With modern turbo technology, and modern engine management systems it's very easy to make an extremely well mannered turbocharged engine.

I'm 100% confident that it'd be possible to build a 150bhp 1.3 turbo that'd utterly spank a 120bhp 1.6 n/a motor on track, on the drag strip, and on the road. Building a 150bhp 1.3 turbo that'd out-do a 150bhp 2.0 n/a motor would be more of a challenge. The trouble is, turbos have a bad reputation - partly because amongst modifiers there's a tendancy to start chasing dyno numbers, and bolting on vastly oversized turbochargers with little regard for driveability is an easy way to achieve them.

No offense,but.. :) what are you trying to achieve? I'll be honest - you dont know what you're doing and you're going to pay alot of money,and spend alot of time messing about,building something that's going to break real fast - by the sound of it so far. Why do you want to polish and port the head? Little point without serious boost pressures - turbo cylinder heads are rubbish standard jobs. They dont need flowed ports as the air is under pressure anyway. Putting carbs on a turbo engine doesnt get good results because of this,so you're clearly misguided on the basics. If you dont get it set up properly,even 130bhp is gonna blow holes in pistons. You ask about outright power,but turbo's dont rev freely or have much low torque. I'm using a free-revving circa 120+bhp 1.6 and in the real world its flexibility means it'd probably hold a 150bhp 1.4 turbo,which only has that power in a narrow power-band at high revs. If you're building a Santa Pod runner,you'd better start concentrating on strengthening issues. Not just the engine internals,but uprated driveshafts,gearbox,final drive etc etc.

yea, turbos are shit

My mates 2 litre rover only gives 375 lb/ft of torque at 4000rpm

and only revs to 7500rpm

really shows how shit turbo cars are

he is going to take the turbo off and fit bike carbs, so he can get more talk

I'm guessing thats a 2.0 litre diesel then? Electronic or mechanical fuel pump?

Simon

some waffle

yea, turbos are shit

My mates 2 litre rover only gives 375 lb/ft of torque at 4000rpm

and only revs to 7500rpm

really shows how shit turbo cars are

he is going to take the turbo off and fit bike carbs, so he can get more talk

I'm guessing thats a 2.0 litre diesel then? Electronic or mechanical fuel pump?

Simon

Nope, petrol.

Lol should of realised when I saw it revs to 7500! lol Some diesel...

Not a VVC was it, I thought the only did them in 1.8, tomcat then?

lol

Simon

Edited 19 June, 200719 yr by zombie1000

I'd have thought it would have been more likely it was a T-series, those motors take some bashing, unlike the K-series.

A) At no point did i ever call a turbo shit,so stop putting words into my mouth.

B) Free-revving has nothing to do with how high an engine can rev.

C) The 2.0 engine claimed to have 375 lb is clearly running serious mods,perhaps you could do something as impressive with a 1.4 VW small block and Passat turbo over a 1.6 carb? I'm ready to take notes. Let us know when you're done.

D) At no point have i said that 120bhp is anything special from a 1.6. If I've spent my seemingly rationable quantities of necessary references to something appropriate to the subject,that I've done myself and have recent experience of,then i'll never mention it again - if that's helpful. If you wanna talk about two litre turbo's,i have recent experience of Subaru's,and that of high tune GTi-R's. But this isnt a suitable topic,is it?

A) At no point did i ever call a turbo shit,so stop putting words into my mouth.

B) Free-revving has nothing to do with how high an engine can rev.

C) The 2.0 engine claimed to have 375 lb is clearly running serious mods,perhaps you could do something as impressive with a 1.4 VW small block and Passat turbo over a 1.6 carb? I'm ready to take notes. Let us know when you're done.

D) At no point have i said that 120bhp is anything special from a 1.6. If I've spent my seemingly rationable quantities of necessary references to something appropriate to the subject,that I've done myself and have recent experience of,then i'll never mention it again - if that's helpful. If you wanna talk about two litre turbo's,i have recent experience of Subaru's,and that of high tune GTi-R's. But this isnt a suitable topic,is it?

yea, pretty sure I could do something better with a 1.4 small block and a turbo, over fitting a set of carbs

but tbh, i wouldnt bother

I would just build a 1.6 16v for less than it cost to fit, and a hell of a lot less arseache setting up some bike carbs would, and it would produce more power and rev so much more freely

Edited 19 June, 200719 yr by Jez

I think I'd rather have an 8v on bike carbs just for the fun factor.

I think I'd rather have an 8v on bike carbs just for the fun factor.

the fun of what? less power? or poorer fuel consumption? or both?