8/85 Nissan 720 - turbo advice

Submitted: Thursday, Feb 16, 2006 at 11:19
ThreadID: 30831 Views:7283 Replies:4 FollowUps:2
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Hi all, Yep an other 720 pops up in forum discussion. I've got this old faithful workhorse that needs the engine refreshed. Before I get the parts and spend the labour bucks I wonder if any of you have comments on putting a small turbo on the SD25. Been told they don't do well, but couldn't find out why or if that included an intercooler or other mod cons.
Currently there is no power steering or A/C, I mainly use the ute for renovations and hauling the supermotard bike around; on long weekends we head up into the mountains.
The reason for considering a turbo is increased fuel efficiency on the highway and a bit more pull up the hills. Yes, a newer vehicle is an option, but before I buy someone elses problems I'd like to explore my options with this vehicle; I know what it needs and does, so better the devil you know sort of thing.

Thanks!! Danno
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Reply By: Graeme - Thursday, Feb 16, 2006 at 11:59

Thursday, Feb 16, 2006 at 11:59
What......turbo a 720???????? the dynamics of a supermarket trolley.
AnswerID: 155330

Reply By: NUTS! - Thursday, Feb 16, 2006 at 12:09

Thursday, Feb 16, 2006 at 12:09
G'day Danno...
Are you a bit of a mechanic mate? if so, I'd say go for it, otherwise dont wast your $$. I used to have a 720 dual cab and put a turbo on the SD25 after a full rebuild. I dit most of the work myself, except for the machining work. Bought a turbo setup of a SD23 as they are almost identicle, and fitted it, was an IHI turbo.

The rebuild cost about $2K doing most of it myself, which included acid dip block, machine block, machine crank, machine head, new liners, new pistons/rings, new bearings, head recondition including valve guides and seats, machine flywheel and new clutch. You dont have to change copression ratio or anything on these engines, just bolt turbo on and it will still be reliable (as much as it was before anyway).

Turbo cost about another $1K 2nd hand and bolted straight on (i was lucky to find someone selling on ebay with manifolds already made up). New exhaust as it would have needed a new slip joint onto the exhaust manifold anyway cost another $450.

The most i could get out of the the turbo was only 9psi at almost red line otherwise it was averaging 5psi. Fuel usage went up from 10L/100 to 11L/100kms after the injection pump was tuned to pump more fuel in (which cost more $$) Could have spent more time fitting intercooler and welding up a new adjuster for the wastegate but......:

The moral of the story....it was still fairly gutless and slow (only about 38bhp on the rear wheels but about 330NM of torque), had more torque hitting hills but was still quite weak with not much improvement in acceleration. This is part of the reason i sold mine and since buying an 80 series 1HZ with Denco turbo kit, it hauls like you wouldnt believe. Look at a tray back cruiser with 1HZ and fit the turbo kit to that and you wont look back.

If you really want to keep it, use the existing manifolds and weld a piece of U pipe to the exhaust manfolde and weld turbo bold pattern onto that. Do similar job for intake and join to turbo with a piece of hose, then invest in a ball bearing turbo. MOST IMPORTANTLY - before you do anything...MAKE A SNORKEL and fit it ensuring its air tight. I swamped mine twice in about 6" of water because the fan sprayed water onto the air cleaner, bent a total of 3 conrods and had to replace 1 liner.

Hope this helps, If you want more info or some pics, send me an email. cruisernut@gmail.com
AnswerID: 155338

Reply By: westBob - Thursday, Feb 16, 2006 at 20:39

Thursday, Feb 16, 2006 at 20:39
try and find out if a td 27 fits into it.my 1999 terrano bleep s all over my mates 2004 prado 3.0td , out pull him up hills and heaps better economy look into a half cut cheers bob
AnswerID: 155437

Reply By: danno - Friday, Feb 17, 2006 at 09:07

Friday, Feb 17, 2006 at 09:07
Thanks all. The SD25 rebuild may happen either way, but from what NUTS! said, it may not meet my expecations. The td27 transplant is a better idea... all comes down to cost. Cheers and I'll keep y'all posted with progress.
AnswerID: 155516

Follow Up By: NUTS! - Friday, Feb 17, 2006 at 16:28

Friday, Feb 17, 2006 at 16:28
And don't forget, I did it all on the cheap. If you were going to pay someone expect it to cost between $6K to $8K for engine rebuild and up to $4K extra to supply and fit the ball bearing turbo.....

You should be able to afford a Navara 2.7TD dual cab for that money, with change, and like westbob said above, will have heaps better performance!

If your set on keeping it, get a couple of quotes and add them all up....

FollowupID: 409580

Follow Up By: danno - Friday, Feb 17, 2006 at 16:33

Friday, Feb 17, 2006 at 16:33
NUTS! It is all to be done for the lowest possible price. You'd have to be doing it on the cheap if the target is a 720 wouldn't you??It's not that I am cheap, I just like the challenge of it all. Had a quote recently of $790 for linings, pistons, rings, bearings and complete gasket set for the SD25 from my local parts supplies. Got industry contacts for head/block work, so figure without my labour cost it is about $1.2k. End of the day if I sell the 720 and upgrade, the fresh motor will make it easier to sell (and start!!), and I get to sleep at night knowing the new owner doesn't have a lemon.
FollowupID: 409581

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