• Advertisement

4jg2 most HP

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

Re: 4jg2 most HP

Postby handymanny01 » Sun Jan 26, 2020 9:09 pm

No one is saying you aren't seeing 1200 Celsius on a gauge man,,, But if you are , then you are a solid 200c degrees past a compound turbo tractor pull sled with STEEL pistons,,, They run to aprox 1900 Fahrenheit (1037 C) as an absolute max,, and for about 5 seconds,,, As an qualified engineer I can say 1200 degrees Celsius is literally WHITE HOT ,,, so if ya are managing this ,, then you're one of a kind,,, well done to ya! The casting actually looses all strength at that temp,,, and will NOT hold even 20 psi,,, I know this cause our workshop race car (turbo hayabusa powered) blew through its steam pipe manifold at waaaay less than that,,, estimated 900 degrees , 18psi,, Due to an injector failure causing extreme lean burn,,, I'd personally be checking voltage at gauge,, weird dual battery hook up causing 24 volt supply maybe?? 6 volt gauge? Wrong pyro probe? Dunno,, Or at least removing pyro and proofing it against a known temp... all that aside,,, the guys doing the asking on here are just after good honest advice,,, and telling people you can run 1200 degrees Celsius all day is not good honest advice,,, Especially when the thread is about the 4jg2 and what horsepower you can get out of it safely... I made 95kw at wheels out of the old 4jg2,, 20psi / 650degrees celcius , and put the dyno graph up for all to see,,, And it was very reliable,,, So let's keep it on point and civil eh?
handymanny01
Isuzu Baby
 
Posts: 37
Joined: Tue Jul 12, 2016 9:39 pm
Age: 43
Country: NZ
City: Wellington
Vehicle: Isuzu MU 3.1 Vf10 hybrid, ported wastegate, mild port head, custom pump, 3"dump and system, 3" inlet / pod filter, EGR delete, 2" body lift, 2" (ish) suspension lift, 33" on 15" steelies , recaro seats, nardi wheel,,, rear LSD , front "lokka"

Re: 4jg2 most HP

Postby isuzurob » Mon Jan 27, 2020 6:55 am

Has custom wiseco pistons in it, every engine and setup is different, worked for isuzu for 12 years and now build custom isuzu for a living, 4jj1 is the best by far
isuzurob
Global Moderator
 
Posts: 1714
Joined: Mon Jun 07, 2010 6:12 pm
Age: 25
Country: New Zealand
City: Taupo
Vehicle: 1990 Isuzu Bighorn 2.8t/d, 3" extended shackles, 2" body lift, 33" silverstone extreme tyres, Front+rear bars, winch with 40m dyneex rope, 21/2 inch exhaust, lokka's front+rear, custom turbo, emissions removed, injector pump modified and more

Re: 4jg2 most HP

Postby mh1989 » Mon Jan 27, 2020 3:13 pm

isuzurob wrote:4jj1 is a straight bolt into any 4jb1 4jg2 4jh1, custom clutch setup, run full factory loom sensors on ecu or be a man and run the motec ecu system for only 10grand then you have a real engine with bigger turbo and 30+injectors, have done a few now, but hey what would I know running 1200 degree Celsius ae


How strong is the 5 speed (mua?) in the rodeo? Will it hold upto a 4jj1?
mh1989
Isuzu Baby
 
Posts: 14
Joined: Sat Mar 30, 2019 3:22 pm
Age: 29
Country: NZ
City: Hastings
Vehicle: Land Rover Discovery 4bd1t
1992 Isuzu Rodeo 4jb1t

Re: 4jg2 most HP

Postby isuzurob » Mon Jan 27, 2020 6:02 pm

Not strong at all with abuse I'm onto my 5th gearbox with a 4jh1 it keeps stripping the teeth off 5th gear, you you drive nice they survive, and dont labour the engine so the gearbox chatters it will be fine
isuzurob
Global Moderator
 
Posts: 1714
Joined: Mon Jun 07, 2010 6:12 pm
Age: 25
Country: New Zealand
City: Taupo
Vehicle: 1990 Isuzu Bighorn 2.8t/d, 3" extended shackles, 2" body lift, 33" silverstone extreme tyres, Front+rear bars, winch with 40m dyneex rope, 21/2 inch exhaust, lokka's front+rear, custom turbo, emissions removed, injector pump modified and more

Re: 4jg2 most HP

Postby mh1989 » Mon Jan 27, 2020 6:08 pm

Do you know if the gearbox behind the 4jj1 is very strong?
mh1989
Isuzu Baby
 
Posts: 14
Joined: Sat Mar 30, 2019 3:22 pm
Age: 29
Country: NZ
City: Hastings
Vehicle: Land Rover Discovery 4bd1t
1992 Isuzu Rodeo 4jb1t

Re: 4jg2 most HP

Postby isuzurob » Thu Jan 30, 2020 6:15 pm

No the 4jj1 gearboxes are weak aswell have broken 2 of them now, and 1 damaged in the truck still, there all little gearboxes
isuzurob
Global Moderator
 
Posts: 1714
Joined: Mon Jun 07, 2010 6:12 pm
Age: 25
Country: New Zealand
City: Taupo
Vehicle: 1990 Isuzu Bighorn 2.8t/d, 3" extended shackles, 2" body lift, 33" silverstone extreme tyres, Front+rear bars, winch with 40m dyneex rope, 21/2 inch exhaust, lokka's front+rear, custom turbo, emissions removed, injector pump modified and more

Re: 4jg2 most HP

Postby geeves » Fri Jan 31, 2020 2:28 pm

Ive been thinking about that 1200C. It may come down to the placement of the sensor meaning Robs 1200 might not be any higher than everyone elses 650 or so.
2 reasons for this thought.
A long time ago I saw a diagram of combution temperatures in a petrol engine. Center of the combution chamber showed 3000C but at the piston it was a much more moderate 800C Why didnt that melt the piston though? The piston is only exposed to that 800 for a few miliseconds and then has roughly 10 times that long to cool down before the next momentary burn. That same gas has to leave the combustion chamber via the exhaust and the center of the flow would still remain a lot hotter than near the edges. If Rob is measuring the center of the flow he will be getting much higher temperatures.
This is backed up to an extent by the results of a friend that used to have a Bighorn then Mu before converting to the dark side and buying a Pajero. He initially had his egt sensor in the port that was originally for the EGR in the manifold. He had a hole taped in the manifold near where the 4 pipes join and his guage increased 200C and responded quicker to load changes on the engine.
A longer sensor could easily show a higher temperature
Sanding your knuckles before starting work can help. That way you cant skin them
User avatar
geeves
Site Admin
 
Posts: 8452
Joined: Sun May 10, 2009 1:36 pm
Location: wellington
Age: 55
Country: NZ
City: Wellington
Vehicle: 94 bighorn 4jg2
2004 Honda CRV

Re: 4jg2 most HP

Postby paulthepilot5 » Fri Feb 07, 2020 7:34 am

An egt getting to 1200c doesn’t mean the pistons are seeing anywhere near that sort of temp, at least for a short duration. Sure that is hot, You will be supprised what you can get away with for unsustained periods. As Geeves said it is very dependant on prob position. I’ve had an egt probe setup pre and post turbo at the same time. Can guarantee a lot of guys running “safe” post turbo egts are seeing 1000c+ pre turbo and not knowing about it
paulthepilot5
Isuzu Junior
 
Posts: 65
Joined: Thu Apr 05, 2018 8:56 pm
Age: 32
Country: Australia
City: Brisbane
Vehicle: 1995 Rodeo DLX TF 2.8Td tray back
Intercooled
2.5 stainless exhaust and dump pipe
Water/methanol injection
Lots of boost
Lots of fuel

Previous

Return to Engines and Exhaust

Who is online

Users browsing this forum: No registered users and 2 guests