1HD-T vs 1HZ What are the real differences?

[Grylls]

Hey Guys,

I have both motors and am just wondering what the difference is with them. I have had so many people tell me many different stories and I just want to clear the matter up for good. I have been told to put the turbo off the 1hd-t onto the 1hz with less k's but know that aftermarket turbos on the 1hz are bad news. If someone can come up with a bit of a list of the differences then that would be great.

Cheers,

Grylls

[ledgend80]

the 1hdt have oil squirters under the pistons to keep them cool. a turbo on the 1hz should be okay as long as you dont go over the top with the boost. 1hdt will have lower compression. why do you want to put the turbo off the 1hdt onto the 1hz.

[ledgend80]

the 1hdt have oil squirters under the pistons to keep them cool. a turbo on the 1hz should be okay as long as you dont go over the top with the boost. 1hdt will have lower compression. why do you want to put the turbo off the 1hdt onto the 1hz.

[Z()LTAN]

uhhh the 1hz has oil squirters too mate....

[ledgend80]

well i stand corrected then they both have oil squirters. so the only difference i know of then is compression and the injection setup in the heads.

[rapid80]

1hdt is direct injection. 1hz has pre combustion chambers. Factory turbo motors have stronger pistons, 2 stage injectors, bigger fuel lines and pump and a boost compensator.

[fumduk3]

mate i'll be happy to buy the 1HD-T if your not going to need/use it!

[Grylls]

Haha fumduk3 ive had a few people say that to me already

The reason that I was asking is because I picked up an 80 series with the factory turbo'd 1hd-t engine in it plus thrown in with the deal was a 1hz with about half the k's as the 1hd-t. The 1hd-t has an engine knock which the previous owner thought was the big ends but sounds to me that its something up in the head so im just waiting for a guage to do a compression test to see just what is wrong with it. There is no doubt about it that I'm just going to sell the 1hz and fix up the 1hd-t or if worse comes to worse get it rebuilt. I would never have bought the car if it didn't have the turbo motor in it. My last 75 series ute had the 1hz and it was gutless. The main reason why I asked the question though is because I have had a lot of people tell me to do this and that and I'm just getting fed up with people that think they know everything saying that the only difference with the motors is the turbo I just needed to know what the differences with the motors are exactly so I can throw it back in there faces.. thats mechanics for ya! haha

Will post some pictures up of it soon but at the moment need to sell a few things before I can even consider spending money on it

[dug1]

Don't believe the stories about 1HZs having problems with aftermarket turbos. I've had 2- one with a Schwitzer non watyer cooled in a Coaster that clocked up over 400K hauling up mountains under load without any problems.

The other was an 80 series with a DTS kit which I fitted (great kit by the way) and no problems. There are quite a few 75 farm trucks down here fitted with aftermarket turbos no probs.

I have 2 mates with factory 80 turbos which I have driven. One thing I noticed was the aftermarket turbos were better down low (off boost) due to the lower compression I assume. The altitude down here really showed this up.

I kept boost 10psi max (DTS told me 12psi max is OK without intercooler).

Disclaimer- anything will cause problems if regular basic maintenance is not carried out.

[berad]

2nd'ed, 2 mates have 75 utes running aftermarket turbo kits for around the last 3 years with around 300-350k on the clock, running 10-12psi with no intercooler. no problems.

IMO fitting a pyro and keeping an eye on it when its under high load for decent amounts of time is a engine saver.

Oil changes etc go a long way with diesels imo.

In my search of boredom, i came across a online repair/maintenance book for the 1hz 1hdt, for those of you who dont know of one there it is.

http://www.scribd.com/doc/7110020/1hd-1hz-1pzt-Engine

Also, 1hz spec page

http://www.brian894x4.com/1HZspecifications.html

1hdt spec page

http://en.wikipedia.org/wiki/Toyota_HD_engine

comp ratio 1hz 22.4 : 1
1hdt 18.6 : 1

head 1hz indirect injection
1hdt direct injection

There is others but that will give you firing power ahha.

[eugene2380]

i have an 80 with a 1-HZ and it had an after market turbo when i bought it, don't know how long it had been on there. it had done nearly 300,000k's and it did about 40,000 after i got it before it shit itself. now i've fully rebuilt every part of the engine you can rebuild. got it re-bored with slightly bigger pistons too. the 1HDT fuel system is direct injection instead if havin precombustion chambers and they have different rods, pins and pistons to handle the turbo. When i did mine, used the same rebuilt head, but used all the same piston set up a 1HDT has so it can handle the turbo better. thats exactly what a european factory turbo 80 series has in it, a 1hz with those pistons.

[Hamo]

[quote="Grylls"]The 1hd-t has an engine knock which the previous owner thought was the big ends quote]

Take it to a toyota dealer and get them to fix it as its a common problem with this motor.
They will check out the crank and throw in some new bearings with the motor still in the car for under $1000

[midi73]

So on this note. If rebuilding a 1hdt, is it possible to up the compression to around what the 1hz is?
I have noticed the lack of low down torque. I own a 1hdt 80 and a midi with the 14b with is 3.7 litre. I reckon the 14b has more torque than the 1hdt. If I turboed the 14b (which I am going to) I reckon it will probably go better than the 1hdt, or close to it anyway. Im assuming this is partly because of the higher compression.

[Kitika]

Turning up the boost will do the same thing...

[rapid80]

So on this note. If rebuilding a 1hdt, is it possible to up the compression to around what the 1hz is?
I have noticed the lack of low down torque. I own a 1hdt 80 and a midi with the 14b with is 3.7 litre. I reckon the 14b has more torque than the 1hdt. If I turboed the 14b (which I am going to) I reckon it will probably go better than the 1hdt, or close to it anyway. Im assuming this is partly because of the higher compression.

Try upping the off boost fuel setting. Should give you some go off the line and bring the turbo on sooner.

[midi73]

So on this note. If rebuilding a 1hdt, is it possible to up the compression to around what the 1hz is?
I have noticed the lack of low down torque. I own a 1hdt 80 and a midi with the 14b with is 3.7 litre. I reckon the 14b has more torque than the 1hdt. If I turboed the 14b (which I am going to) I reckon it will probably go better than the 1hdt, or close to it anyway. Im assuming this is partly because of the higher compression.

Try upping the off boost fuel setting. Should give you some go off the line and bring the turbo on sooner.

Havent had the 80 long. How do you do this?