4BD1T turbos and boost pressure.

[ISUZUROVER]

A few people have asked about this in the past and I think there has been a bit of misinformation (some may have come from me ).

I finally got my ISUZU WS manual back in my hands, and it says:

1988 and Earlier engines were fitted with an:
IHI RHB-6 (with wastegate). The wastegate opening pressure (boost pressure) was: 680mmHg = 13.15 psi = 0.91 Bar

1989 and Later engines were fitted with a Garrett T-25 with NO WASTEGATE. Maybe this is where the erroneous 5psi boost figure came from, but I don't see why these would run lower boost than the earlier engines.

Can we compile a list of which manifolds take which turbo and have which exit (front, centre, rear)? There are 4-6 different manifolds for the different turbos and different mounting positions.

#8943662470 should be a front or middle exit which takes a T25 turbo.

[1103.9TD]

G'day Ben, I'm still o'seas, so don't have any info at hand, once I get back down south I'll look up the details in my mates ADF Landrover workshop suppliment.

[def90]

hey benny boy,

i have a center mounted turbo (i think) on my manifold (model # 8943662470) and run a garrett - model # 466409-2. (new only $1150, not bad i thought) it has a wastegate.

this what you after?

[ISUZUROVER]

hey benny boy,

i have a center mounted turbo (i think) on my manifold (model # 8943662470) and run a garrett - model # 466409-2. (new only $1150, not bad i thought) it has a wastegate.

this what you after?

Thanks Sam - it was actually you I got the model number from that I quoted above.

How do you like your turbo and what boost are you running these days. Didn't you originally try a 2nd hand one???

[def90]

hey ben forgot about that,

this would have to be may fav turbo, i've had 3 now.

RB20 - was good but started pissing oil everywhere

RB25 - not really any good EGT got hot very easily on freeway and didn't spool up well at all, too big i presume

Garrett built for the 4BD1T - should have got it in the first place, runs better in 3rd 4th and 5th then the RB20 turbo, originally was getting quoted over $2k up to $3.5K, thought bugger that and went the $250 RB20 (was good value for 6 months), then found it for $1150! Now run a catch can to stop the oil feeding back into the turbo, good as gold.

[ISUZUROVER]

hey ben forgot about that,

this would have to be may fav turbo, i've had 3 now.

RB20 - was good but started pissing oil everywhere

RB25 - not really any good EGT got hot very easily on freeway and didn't spool up well at all, too big i presume

Garrett built for the 4BD1T - should have got it in the first place, runs better in 3rd 4th and 5th then the RB20 turbo, originally was getting quoted over $2k up to $3.5K, thought bugger that and went the $250 RB20 (was good value for 6 months), then found it for $1150! Now run a catch can to stop the oil feeding back into the turbo, good as gold.

Sorry - still have 3 Q's:
What boost are you running?
What are your EGTs?
And where did you get the turbo from?

PS - my 110 is arriving today!!!

[def90]

sorry ben,

1/ 12-13Psi, normal driving doesn't really go over 8/9psi

2/ freeway 100k's sits around 300-320 flatish roads, towing my little trailer sits around 340-360deg's. obviously rises when climbing but takes a while to get to 500, usually up the hill by then, cools down extremely quick - still wont a front mount someday. around town sits between 100 - 200 deg's pending how i drive/how long, sometimes sneaks to 250deg's

3/ got the turbo from 'turbo australia' from ross, a good chap

4/ got your 110 sent over to where? u not in germany still are you? or in the states? i can't follow where you been. when you coming home? you looking at doing some touring obviously?

[ISUZUROVER]

4/ got your 110 sent over to where? u not in germany still are you? or in the states? i can't follow where you been. when you coming home? you looking at doing some touring obviously?

Thanks mate. Have a look in the "location" bit to the left. I will be in Brissie on the mid december if you are up for a trip somewhere???

[def90]

what you doing in W.A bud? you know you can't beat the 'sunny (dry)state'

keen for a wheel when you come back!! give me heaps of notice, u still go the SII over here?

[ISUZUROVER]

what you doing in W.A bud? you know you can't beat the 'sunny (dry)state'

keen for a wheel when you come back!! give me heaps of notice, u still go the SII over here?

Got offered a good job. Come over here for a while and you definitely won't call QLD the dry state.

I will give you plenty of notice. The IIA is still in QLD and will be re-regod soon.

[justinC]

sorry ben,

1/ 12-13Psi, normal driving doesn't really go over 8/9psi

2/ freeway 100k's sits around 300-320 flatish roads, towing my little trailer sits around 340-360deg's. obviously rises when climbing but takes a while to get to 500, usually up the hill by then, cools down extremely quick - still wont a front mount someday. around town sits between 100 - 200 deg's pending how i drive/how long, sometimes sneaks to 250deg's

3/ got the turbo from 'turbo australia' from ross, a good chap

4/ got your 110 sent over to where? u not in germany still are you? or in the states? i can't follow where you been. when you coming home? you looking at doing some touring obviously?

I advocate the fitment of the IC immediately, I find it definately is worthwhile. I can run up to 600 deg (upstream) up a tortuous hill in top, hop out and feel the temp difference between the intake and outlets of the cooler, HUGE difference. The outlet to the inlet manifold is actually COOL, whereas the pressure side from the turbo is very warm, I'll do a infrared comparison when I get my temp probe back from the person who borrowed it last!!! Go the IC ASAP. I'm using a centre feed manifold, with a watercooled GArrett TB25 wastegated unit, at around 10 to 12 PSi at the manifold. I have a front mount that fills the front grille area of the Rangie, and extends down to the bottom of the bullbar channel. I've cut out the fairlead slot a fair bit to get more air in too.
I lurve forced induction....

JC

[KiwiBacon]

I've got the japanese import 4BD1T with the IHI RHB6 turbo.

When I got my truck, the wastegate had never opened. I had a max of 12psi boost (rooted compressor wheel).
Managed to find a second hand compressor wheel and cover, boost went to 18psi.

Being curious I hooked up a bike pump and pressure gauge to the wastegate line. It started to crack open at 20psi and was fully open at 25psi.

I cut the wastegate arm and added a threaded section which I used to set the boost to roughly 15psi. At 15 it went far better than at 18. With no intercooler the higher intake temps and extra exhaust restriction robbed more power than the extra 3psi of boost could give.

BTW I need another new compressor wheel, they're impossible to find here.

[1103.9TD]

Kiwibacon, I'm running the same setup without the threaded section, and getting 12.8PSI - which I believe is standard. The three inch exhaust makes a good deal of difference to performance, especially initial lag. I've contacted ARE in Brissy to enquire about a water to air intercooler, but they are not cheap!!!. Have you heard about anyone using a Subaru or Toyota WTA intercoolers on the Isuzu, are they enough capacity wise?. Like to post some photo's, but forgotten how on this forum!!. [/img]

[KiwiBacon]

Not sure why my wastegate was set so high, maybe something wasn't made to spec resulting in a wastegate rod that was too short for the job.

I made my own half-arsed water/air intercooler setup, I sleeved a section of intake plumbing, cut the inner section out and wound in 2.5m of 3/8" copper tube which the water circulated through. Initially using a belt driven washing machine pump, then an electric subaru pump. I fitted a small radiator out front to cool the circuit.

I filled it full of temp probes and found I could only get 15% of the heat out of the intake air, so I gave up.
My engine bay is a little tight to fit a subaru water/air cooler, a PWR type may fit but I plan to do it properly with a front mount air/air eventually.

My exhaust is 2 1/4", bigger would be nicer but it's quite a way down the priority list. What rpm do you get boost in yours and what rpm does full boost arrive?
I've got a few psi around 1500rpm, but doesn't reach 15psi until about 2300. I do need a new compressor wheel so if you find a source of parts, please let me know. NZ turbo repairers can't get any.

[1103.9TD]

I can't get any accuracy RPM wise at the moment, until I get my VDO tacho calibrated, but it sounds about right. Got a brand new turbo in mine, as I starved the old one of oil. Had a wierd accumulator system to feed oil through the turbo, when the engine was turned off, but which also starved the turbo of oil pressure on start. I removed it, and screwd a tapered bung in, unknowingly stopping a bearing valve from moving = no oil to the turbo. It was showing some shaft and bearing wear, so it wasn't a total tradgedy. Sorry, me and a mate both run the same setup here, so we wanted the old turbo to rebuild as a spare. Try MTQ for the parts you're after, I'll keep an eye out, and let you know.
Have a look at the ARE website, their WTA intercoolers are something else, be nice (cheaper) if we could give them an order for 5 or so!.

[KiwiBacon]

I've got another turbo in my garage which I'm cleaing up. It's the Garrett T25 (no wastegate) from a 4BD2.

Comparing it to the T25 (wastegated) from a Nissan CA18DET (bluebird) is interesting.
Compressor wheels are identical, 51.3/40mm (60 Trim). Compressor covers are the same A/R (0.48).
Exhaust wheel from the 4BD2 is slightly smaller (53mm vs 50.6) but larger trim (0.83 vs 0.63) and shorter (22mm vs 16mm). Exhaust cover A/R is 0.47 from the bluebird and numbers which might be 0.58 from the 4BD2.

Last time I tried a wastegated T25 my engine was quite sick, now I'm keen to try it again and still have all the parts (just need another T25).

I plan to stop using the IHI as soon as I'm happy with a replacement. The T25's are soo common and cheap here, the ricers all ditch them for bigger turbos.

[andrew e]

Have a look at the ARE website, their WTA intercoolers are something else, be nice (cheaper) if we could give them an order for 5 or so!.

My water to air cost $350, but took some work to fit - bonnet buldge, Y pipe, silicon bends, modified front feet, but its very noticable even with a small inlet hole in the bonnet cooling the radiator.

I have now found a air temp probe, so i can measure the difference between before and after the IC when i get a chance. If i were to guess the max the inlet air would get is about 50 deg C. as on the hottest days after pushing it hard you can still touch the outlet pipe from the IC comfortablly. As for the inlet, it has melted some of the powdercoating off part of the Y piece.







Andy.

[1103.9TD]

Andrew, that system looks slick as, but my intention was to have a large radiator, in the place of the old A/C evaporator, and pump the water from that into a reasonably efficient WTA cooler, mounted just prior to the standard inlet manifold.
Stupidly, I want to put a spare on the bonnet when I go bush.....

[1103.9TD]

And how the f#*k did you post those pics.....

[andrew e]

And how the f#*k did you post those pics.....

its posted through putfile.com , you register, download your pics to putfile, then paste the link to outers. its easier than it sounds.


The reason i axed the bonnet up and stuck it up there is because there is no room in the bay anywhere (for an IC anyway). First i tried mucking around with a subaru one, but that was worse than the toyota one with twin inlets.

You could still put the radiator for the IC behind the grille infront of the radiator. I cant, as i moved my ARB winch bar back almost 3 inches and have a highmount sitting inside my axed up non aircon grille.

I couldn't imagine looking over a 35x12.5 tyre on the bonnet!!

PS hows that aircon working?

[1103.9TD]

Ok, thanks, I'll give it a go.....It worked!, checkout that brand spanking turbo, thanks for your help, Andrew, the A/C stiil cools to 4degC inside, on a hot day in Cairns - I have to watch the beer doesn't freeze in the Engel's...

I reckon a WTA intercooler would fit on the RHS of the engine, bolting straight onto the inlet manifold....

[andrew e]

neither a sube or toyota one will fit in that space. mabe a custom one. thinking about it, they wouldn't be too hard o make one from a stansard intercooler. Go to a jap import/wrecker and try a few standard intercoolers, then what ever one fits, take it to a sheety and have it boxed in 2mm ally. have 2 pipes for the water and one small one for an expansion tank, and you have a custom w to a intercooler.

Andy

ps pics and details on your AC unit please.

[KiwiBacon]

Is that a brand new IHI? Mind me asking how much?

I've considered plating in an air/air intercooler to make a water/air. But I found the only ones small enough for the space I had would be too restrictive.

Has anyone tried the cylindrical air/water coolers, made possibly by PWR?

All roads for me keep leading back to front mount air/air.

[callum]

hmm, maybe i'm speaking when i dont really know the circumstances, but i think a front mount air to air is the way to go or at least a good alternative.

there's some pics of my front mount here...
http://forums.lr4x4.com/index.php?showtopic=7909
(might have to log in)

trouble is that's with a little tiddler 2.8 isuzu. i moved my radiator back a bit and slotted it in. of course that was cool as i have loads of space and electric fans. i dont know if ditching the viscous fan in favour of slimmer electric efforts is viable in aus.
i expect many vehicles have little air con rad's mounted infront of their main rad's, which rules out putting it where most front mount aftermarket coolers would normally go (for defenders at least).

well there's some thoughts i suppose, not sure if they're terribly useful ones. in favour of front mounts they're not too complicated.

[ISUZUROVER]

hmm, maybe i'm speaking when i dont really know the circumstances, but i think a front mount air to air is the way to go or at least a good alternative.

Air-air is simpler and cheaper but nowhere near as efficient as water-air. Add to that, water-air works almost as well wether you are only going slowly.

But up there in edinburgh you probably wouldn't notice the difference - especially not at this time of year!!!

[KiwiBacon]

Air-air is simpler and cheaper but nowhere near as efficient as water-air. Add to that, water-air works almost as well wether you are only going slowly.

Why do you say air/air isn't as efficient? Sure you need a bigger radiator up front than a water/air but both get the heat out fine.

My main concern with an air/air offroad is damaging it and sucking crap into your engine on the way home.

Slow speed is an issue with both types unless you've got fans. A water/air will take a little longer to heat-soak if you've got a big water tank.

[ISUZUROVER]

Why do you say air/air isn't as efficient? Sure you need a bigger radiator up front than a water/air but both get the heat out fine.

If you really want to know - here is a respons I prepared earlier to a similar question:
The specific heat capacity of WATER is about 4180 J/(kg.K) - where J=Joules (energy) and K= Kelvin (degrees celcius + 273.15). Specific heat capacity is the amount of energy that is required to raise the temperature of one kg of the substance by 1 Kelvin.

so it takes approx 4.2kJ of energy to raise 1kg of water by 1 degree celcius/kelvin.

By contrast, the specific heat capacity of AIR is 1.05 J/(kg.K) in a constant pressure process e.g. 1 atmosphere (specific heats of gases are calculated slightly differently but this is close enough for here).

So therefore, on a kg for kg basis water has about 4000x the cooling capacity of air.

[KiwiBacon]

So therefore, on a kg for kg basis water has about 4000x the cooling capacity of air.

Sure does.

But a water/air system still needs exactly the same mass flow of air through the cooling radiator to cool it.

The only difference is you have an intermediate stage of water.

Air/Air or Air/Water/Air

[ISUZUROVER]

So therefore, on a kg for kg basis water has about 4000x the cooling capacity of air.

Sure does.

But a water/air system still needs exactly the same mass flow of air through the cooling radiator to cool it.

The only difference is you have an intermediate stage of water.

Air/Air or Air/Water/Air

Agree, but since the cooling rad can be located anywhere and sized appropriately, the important thing is being able to get rapid cooling of the air passing through the IC.

Maybe we need a refrigeration system to cool the water instead

Any updates on your plans/progress...

[KiwiBacon]

Any updates on your plans/progress...

I've rebuilt my T25 turbo (wastegated CA18DET item), had injector nozzles rebuilt, picked up a rebuilt injector pump dirt cheap (spare), picked up a large XSPOWER water/air cooler, bought a GT2256V variable vane turbo and a T2860 from a skyline (steel wheel).

I'll fit it all in one day, but I'm still in the detailing side at the moment. I've got the LT230, gearbox and engine out, currently cleaning, tidying and painting everything. Years of accumulated oil and dirt take a bit of removal.
I've just been told to try oven cleaner. That'll be interesting.

A new adaptor shaft between the Isuzu box and LT230 is being made, the engine and box can't go back in before then.
I've also got a periodic rumble in my 1:1 LT230 which needs investigation. I suspect tooth decay, previous owner didn't floss it regularly enough.

When the gears are sorted it'll be going back together with the T25 turbo. Then add the intercooler, then it's the compound turbos.