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engine combination possibilities

Getting the best performance from your Isuzu, the in's and out's

Re: engine combination possibilities

Postby rabidrabbit001 » Fri May 08, 2015 11:12 am

4JG1 PISTON DIMENSIONS
Image
http://morida-taiwan.com/product-detail.php?pid=14&sid=17&id=95
4JG2T PISTON DIMENSIONS
Image
http://morida-taiwan.com/product-detail.php?pid=14&sid=17&id=97
For a larger height difference of .3 mm for the 4jg1 pistons.
That's like two hairs thick.
Can this height not be resolved by the use of a 4jg1 head gasket?
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Re: engine combination possibilities

Postby geeves » Fri May 08, 2015 2:40 pm

If its really an issue it would be possible to skim that much off the top but I would just pick the thickest gasket as well. Remember its a different head
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: engine combination possibilities

Postby rabidrabbit001 » Fri Jan 15, 2016 2:53 pm

Ok here is an update. I am driving my 4jg2t to 4jg1t conversion. First thing is the damage found in the 4jg2t head when removed. All cylinder chambers had cracks of varying sizes. All has chamber cracks and all had cracks between valves.
Image
Image
Last edited by rabidrabbit001 on Tue Sep 06, 2016 12:59 pm, edited 1 time in total.
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Re: engine combination possibilities

Postby rabidrabbit001 » Fri Jan 15, 2016 3:10 pm

Here are the new pistons chamber and top polished. Before on left after on right:
Image
Last edited by rabidrabbit001 on Tue Sep 06, 2016 12:50 pm, edited 1 time in total.
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Re: engine combination possibilities

Postby rabidrabbit001 » Fri Jan 15, 2016 3:13 pm

New liners...dry ice method used and works like a charm.
Image
Last edited by rabidrabbit001 on Tue Sep 06, 2016 12:46 pm, edited 1 time in total.
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Re: engine combination possibilities

Postby rabidrabbit001 » Fri Jan 15, 2016 3:20 pm

New main and rod bearings. Head chamber polished. Complete match ported and polished. (4JG1T generator head)
Image
Last edited by rabidrabbit001 on Tue Oct 04, 2016 1:19 pm, edited 4 times in total.
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Re: engine combination possibilities

Postby rabidrabbit001 » Fri Jan 15, 2016 3:35 pm

3 notch head gasket
Image
Last edited by rabidrabbit001 on Tue Sep 06, 2016 12:47 pm, edited 1 time in total.
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Re: engine combination possibilities

Postby rabidrabbit001 » Fri Jan 15, 2016 3:44 pm

Also did a complete belt timing to gear timing swap. (4jb1 rear and front cover/gears) oiler tube not shown. Yes I installed it after photo. 2 parts needed to complete swap: cam thrust plate and remove plug behind idler gear (A) from block for oil galley to allow oil flow to idler gear and oiler tube.
Image
After running the 4jb1 gears for 2 weeks I decided to use the 4jg1 gears that I had also purchased. They are alot quieter. Less chatter and the motor seemed to tune better after 4jg1 gears installed. Idle also seems smoother.
Last edited by rabidrabbit001 on Tue Sep 06, 2016 12:43 pm, edited 1 time in total.
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Re: engine combination possibilities

Postby geeves » Fri Jan 15, 2016 4:12 pm

Its coming along well
That 4jg2 head wasnt going to be going much further.
Are those steel or chrome liners? (remember rings and bores must be one of each not the same)
Any dyno figures?
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: engine combination possibilities

Postby Roderunner » Fri Jan 15, 2016 8:44 pm

Nice!..... Did you do a piston to valve clearance check with the various gear drives? I ask because the 4jg2 has 50 degrees of valve overlap according to my workshop manual, I haven't got any duration figures for the 4jb1 engine to compare that figure with.
While you have your hands greasy could you please measure the valves on the 4jg2 head as I want to know if the belt drive engine has the same valve sizes as the gear driven 4jg2. Thanks, if you could keep us posted on your progress it would be appreciated. cool build by the way.
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Re: engine combination possibilities

Postby rabidrabbit001 » Sat Jan 16, 2016 8:44 am

4jg2t
Intake valve 42mm.
Exhaust 35.5
4JB1T
Intake 40mm
Exhaust 35.5
I'm using the 4jg2t cam....no interference issues.
I was not aware of a difference in 4jg1 and 4jg2 cams. Is there a difference. I also have been using the 4jb1t 4 hole nozzles and am going to try swapping in the 4jg1t 5 hole nozzles. Hopefully better and more complete burn yielding a more efficiency.
Do you guys have any suggestions for more fuel efficiency.
Stock 4jg2t downpipe, to 1999 Trooper 6vd1 stock 2.25" exhaust.
Subaru STi large hood scoop for better air flow over intercooler. I think I need to change over to a fmic eventually.
Running 31" inch tires (305/65R17) Mickey Thompsons
Timing is set to .55mm @ 12°btdc.
Book says .50mm @12°btdc....but I read somewhere if I can advance that by .05mm it has better performance and fuel efficiency. So far only seeing 22-23mpg or 10.69-10.23L/100km
.Image
I loved this Trooper and intend to keep it as long as it will keep me. I believe this is the only Trooper in North America with this engine setup as far as I have read and seen online. All parts are accessible through local isuzu industrial and highway parts dealers...if you have the part numbers it makes it a lot easier. I found the most of my larger parts from http://www.freewai.com and searched 4jb1.
Last edited by rabidrabbit001 on Tue Sep 06, 2016 12:42 pm, edited 1 time in total.
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Re: engine combination possibilities

Postby rabidrabbit001 » Sat Jan 16, 2016 9:28 am

geeves wrote:Its coming along well
That 4jg2 head wasnt going to be going much further.
Are those steel or chrome liners? (remember rings and bores must be one of each not the same)
Any dyno figures?

I purchased overhaul kit from here:
http://www.partsfamily.net/isuzu-4jg1-4 ... p-808.html
Checked rings to each bore and all checked out within book spec tolerance.
No noticeable blow by coming from oil dipstick tube or valve cover.
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Re: engine combination possibilities

Postby geeves » Sat Jan 16, 2016 2:45 pm

looks nice. Re ecconomy its good to quote l/100km as we can all relate to it. Here in NZ 10.23 l/100km would be read as about 28mpg because our gallons are bigger (or were before we went litres) In a 2 ton + truck and not knowing how you drive and with quite wide mud tyres I wouldnt expect much more than that. Was this Freeway driving and what speeds? How much traffic? If you get this in stop start or at 120kph its a good figure
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: engine combination possibilities

Postby Roderunner » Sat Jan 16, 2016 7:12 pm

= rabidrabbit001
I was not aware of a difference in 4jg1 and 4jg2 cams. Is there a difference.


I only have the specs for the 4jg2T cam, so can't help you there.

I also have been using the 4jb1t 4 hole nozzles and am going to try swapping in the 4jg1t 5 hole nozzles. Hopefully better and more complete burn yielding a more efficiency.


Which engine's injection pump are you using?

Do you guys have any suggestions for more fuel efficiency.


The mileage already sounds good for a Trooper, but if you are after every last mpg then you might want to look into the mean piston speed at cruise. The best piston speed for fuel consumption is 1000 to 1400 feet per minute according to an engineering website I visited some months ago. The equation for mean piston speed is Stroke x rpm / 6 = mean feet per minute, the troopers 4.212" stroke gives the following piston speeds according to my math.
1500 rpm = 1053 ft/min
2000 rpm = 1404 ft/min
I wouldn't like to try the 1500 rpm for cruising at 60 mph, too much downshifting on hills I am thinking. The 2000 revs cruise figure sounds doable, in fact there is a member of this site who claims to run this gearing, and he claimed to get 9 l/100 K if I remember correctly, but his name escapes my memory's recall ability. Interestingly the Rodeo's 3 litre 4jj1 engine sits on about 1700 revs at 60 mph, but they are a 4 valve per cylinder engine with a computer controlled injection system, so torque numbers are higher than our 2 valve mechanically injected beasts.


EDIT: I found this post
posted by moseswal2 » Thu Mar 29, 2012 10:59 pm
I have a 4JG2 engine, 4JA1 gearbox and 3.7 diff.

The revs are at 2000 at 100 km/h. What ever my spedo says I have to add 20.It not much more economical but its much more comfortable for long distance and accelerates quicker. I get about 9 l / 100 km.
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Re: engine combination possibilities

Postby rabidrabbit001 » Mon Jan 18, 2016 1:21 am

geeves wrote: Was this Freeway driving and what speeds? How much traffic? If you get this in stop start or at 120kph its a good figure

In city driving , highways, and rural driving. Yes stop start. And yes up to 120kph (74mph) I also have it loaded down with all my work tools...tile flooring
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Re: engine combination possibilities

Postby geeves » Mon Jan 18, 2016 5:03 am

consider the mileage good
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: engine combination possibilities

Postby rabidrabbit001 » Tue Jan 19, 2016 2:04 pm

Does anyone have access to a full set of 4jh1 timing gears including the twin scissors gear, and the injection pump timing gear pully that bolts to the corosponding gear?
Like the ones pictured here Image
Image
I am thinking of making this setup work on my 4jg1t setup. So I will need anything that will be related to bolting the gears to the case or block...spacers, bolts, all of it.
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Re: engine combination possibilities

Postby Craigdivie » Tue Apr 19, 2016 3:09 am

The 2.5 Go big pump gear mates with the 4jh1t timing gears, and it mounts on the 4jb1t pump. I use this set up on my 4jh1t, I have done away with the electronic pump and run the 4jb1t pump and injectors (74kw)
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Re: engine combination possibilities

Postby Mudbomber » Mon Sep 05, 2016 7:00 am

Howdy, I was wondering if you could repost the pics between the valves? I have them on mine but I also blew my head gasket :S
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Re: engine combination possibilities

Postby cocholi » Thu Oct 06, 2016 1:55 pm

Hi, I'm from Chile, I have a 92 trooper swap to 4JB1T and after 4JH1-TC, 3.2 manual transmission with 4JH1 bellhousing, I belive is the only in the world, moreover swaped to twin piston front brake caliper, hid protector, etc...

4jh1 is noisly than 4jb1, litle more power, beter milleage, and a lot of wires. The 3.0 is from 07 Chevrolet D-max 4x4 (Isuzu trf?)
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