Outer Limits 4x4 Board

Could someone please explain to me what a hi-flow is and how you do it to a turbo and what is the benifit.

machining out the internals and fitting higher flowing compressor or modding the exhause side to make turbo spool faster or pump more air

basically putting higer flowing (bigger) internals into your turbo

cool thanks for that,

Is it worth doing to what seems to be a smaller turbo? or should I investigate a larger one. Is it as simple as just getting a bigger turbo. Guessing if you hi flow or get a bigger turbo, that you need more fuel?

What sort of prices would I be looking at as a ball park figure, and would it reduce temps on the engine as it wouldn't be working as hard to do the same job?

Thanks

It depends on many things.

Fitting a physically larger wheel will have benefits. But on some turbos you'll only be able to fit a bigger trim wheel. Bigger trim means the outside diameter is the same size, but the wheel has less step down towards the intake so the intake side is bigger.

Bigger trim wheels require high flow to generate boost, they can't produce high boost at low airflows (that a diesel 4wd typically needs) without having surge problems.
Surge is when the boost pressure escapes back through the turbo compressor in pulses. It's not good.

In some applications its ok, but we have seen a few td42 turbos high flowed, they tend to be a bit laggier down low. The only other option is to match a bb unit which will then spin up quicker.


What sort of vehicle are we talking about?

Andy

A Nissan 2.7TDI 99 model Terrano II.

I can get it chipped for more get up, but wondering if there are other options to get more out of it without having to trick the ECU.

Other than the rising temp and it bogging down off the line I am very happy with it as I came from a 2.8N/A diesel so even though its a small TD engine its heaven to me at the moment.

I seems to get hot quite quickly when driving so I was wondering if making the turbo work less for the same result would help the temp issues. I am all fairly new to all this but keen to learn, so I am talking about things I don't really know about.

It doesn't hit boost till about 1600ish rpm and below that is very sluggish. If you put your foot down below that it just boggs down untill it reaches boost which seems like it takes for ever. I'm not looking for a rocket ship, but something that pulls from quite low and stays cool. I plan on getting the exhaust done as a straight through (if you know someone good in sydney it would be appreciated) and then getting a pyro fitted to monitor the temps. Hopefully that will free things up and keep temps down a little?

Check the airflow meter first - have had same prob on one before
dirt builds up on the hot wire and wont read airflow correctly. - remove airflow meter and clean / spray with contact cleaner or similar , good Luck.

What sort of temps are you talking about?

there could be a problem.

I have the older TD27t engine and of late I can't get it above the cold line, turbo seems to boost between 1200 and 1500rpm, though I don't really notice the boost coming on as it seems to pull pretty good all the time.

If it gets real hot (last few months) it might hit the 1/4 mark on the temp guage, last summer it was only getting up to the 1/2 way on the temp guage and that was going through sand as well.

Oh you can upgrade the turbo if you wanted the max would be a KKK gt21 A/R 0.61, the turbo on the TD27t is a hitachi or KKK same maker.

Should bolt straight up, I seen on a forum someone saying you could expect 160rwhp out of the td27 diesel.

look on this page for your make and year for the stock turbo used.

http://www.dieselevante.it/turbocharger ... 16&idcat=2

it sits on half way once it has warmed. doesn't fluctuate in traffic, but even on the weekend down at the snow, when I was going up hills the temp guage rises to half way between 1/2 and 3/4. I have had it up to 3/4 once but then backed off. It only seems to happen when going up hills. Dropping down a gear to higher revs, but less stress on the engine doesn't drop temps according to the gauge. and once at the top of the hill and back on level grounbd drops fairly quickly back to 1/2. I have heard of others with this problem, but no one is yet to beat it. You either have it or you don't. Others have tried aftermarket raidiators, new fans etc etc etc. but to no avail.

My problem is that although the gauge fluctuates, without a pyro I have no idea how big the fluctuations are in degress celcius terms, and whether I am pushing it to hard.

Anyone got any ideas.

Will try cleaning the O2 sensor as I got some contact cleaner today.

My first step was fit a pyro and boost gauge to know exactly why you get in your engine .. also a mechanical water temp are not a bad idea ..

Actually you can get much better performace from a well fitted and sized intercooler than a new turbo ..

Fairly positive it is a garret turbo. I have seen the plate on it saying that, but can't read the spec #'s

tritontray wrote:Fairly positive it is a garret turbo. I have seen the plate on it saying that, but can't read the spec #'s

I'd expect a T25.

I'll see if I can get all the numbers off it that are punched into the plate below the Garrett logo.

Thanks for the continued help as well guys.

Ok its definately a Garrett.

#'s as punched in on plate.

CF2273 1
1441177 F400
452 162-1

Is anyone able to decipher these for me?

Thanks

tritontray wrote:Ok its definately a Garrett.

#'s as punched in on plate.

CF2273 1
1441177 F400
452 162-1

Is anyone able to decipher these for me?

Thanks

The 14411 is the same as my T25. The rest differs and I haven't seen enough to decipher it all.

Your only "hiflow" options for a T25 are:
1. T25G compressor wheel, this is a bad idea, it will surge badly trying to get boost at low rpms.
2. T28 compressor wheel. Requires a lot of machining, will be very expensive.
3. Sell it and get a ball bearing T25.

Ha Ha....I guess its option number three. Any Idea of cost on a new BB unit?

Dropping back a gear for up hills does take a load off the engine but makes the engine rev higher which then makes the turbo spool faster causing higher temperatures. First thing i'd do is fit a boost gauge to know exactly what sort of boost your running, if it is higher than standed your problem will most likely be solved by lowering the boost to standed. but if you like the power it has your best bet is fitting a bigger radiator, not that expensive but very effective, i know because i have had this problem in the past. If this still does not fix it i'd be getting the engine looked at for problems, head gasket maybe??

Thanks for all the help.

I cleaned the o2 sensor, and since then it seems to have done something. Maybe its just a placebo but I think it has done it some good. Someone above mentioned it should be cleaned, but will it have helped to fix the heat issue?