• Advertisement

2 questions

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

2 questions

Postby tonkamu » Thu Oct 04, 2018 6:12 pm

Hey all, anyone know if changing from 2.5" straight pipe to 3" pipe on a 4jb1, is it a big difference in sound and go? I'm thinking 2.5" is still restrictive.

I also had another question might be more aimed at diesel experts, is it better to run a lot of fuel and a boost tap/controller OR just enough fuel to reach desired boost with disconnected wastegate?
tonkamu
Isuzu Senior
 
Posts: 156
Joined: Sun Jan 01, 2017 7:23 am
Age: 36
Country: NZ
City: Auckland
Vehicle: 2.8 Mu 1991 All Black. MODS - Rear Lifted 2.5" Lovells Leafs / Rear Auto Locker / LSD in front / 33x12.5x15 MT Achilles / 9500 RUNVA w plug n kills switch inside cab / EGT, Voltage, Turbo timer, Boost gauge / 20 PSI VF10 Turbo with VF10 exhaust housing 2.5" downpipe with merged 2" wastegate pipe to full 2.5" straight pipe / GFB Boost Tap / Maxed fuel with grinded down cable stop / Adjusted Boost Compensator / 3.1 Oil Cooler / Intercooled / 3" Custom intake to sealed K&N airbox & filter to Snorkel / Catch Can / Xtreme Outback HD clutch / 80 amp alt / RockfordFosgate 300rms AMP w 2X Rockford Power 6x9's BT HDeck / all EGR, QWS, AC pump deleted.

Re: 2 questions

Postby paulthepilot5 » Thu Oct 04, 2018 8:38 pm

tonkamu wrote:Hey all, anyone know if changing from 2.5" straight pipe to 3" pipe on a 4jb1, is it a big difference in sound and go? I'm thinking 2.5" is still restrictive.

I also had another question might be more aimed at diesel experts, is it better to run a lot of fuel and a boost tap/controller OR just enough fuel to reach desired boost with disconnected wastegate?


There will be more noise but probably won’t see massive gains on a stock engine going from 2.5 to 3 that being said every little bit still helps.
paulthepilot5
Isuzu Junior
 
Posts: 129
Joined: Thu Apr 05, 2018 8:56 pm
Age: 38
Country: Australia
City: Brisbane
Vehicle: 1995 Isuzu Rodeo 2.8d
Compound twin Turbo
12mm fuel Pump
+50 injectors
Water/meth injection

TF Rodeo ute 2WD short wheelbase
2.8 4JB1T
Inline injection pump conversion
+50 injectors
Borg Warner s200 turbo
300hp, 650nm

Re: 2 questions

Postby geeves » Fri Oct 05, 2018 5:23 pm

Set fuel so it smokes at full throttle and load then back it off till the smoke stops. You need other mods to go past 16psi
Sanding your knuckles before starting work can help. That way you cant skin them
User avatar
geeves
Site Admin
 
Posts: 8962
Joined: Sun May 10, 2009 1:36 pm
Location: Rangiora
Age: 63
Country: NZ
City: Rangiora
Vehicle: 94 bighorn 4jg2
2013 Subaru XV

Re: 2 questions

Postby tonkamu » Fri Oct 05, 2018 8:07 pm

OK so I only have a gauge that reads 20psi. I've turned my fuel screw about 7 turns in. I have a lot of mods. with wastegate disconnected it feels like im over 200hp. I'm running a bigger turbo and exhaust with a lot of air intake. I know what 200hp feels like and its around there. All goods just wanted someone to tell me if they have gone from 2.5 to 3" and tell me if its worth the money.
tonkamu
Isuzu Senior
 
Posts: 156
Joined: Sun Jan 01, 2017 7:23 am
Age: 36
Country: NZ
City: Auckland
Vehicle: 2.8 Mu 1991 All Black. MODS - Rear Lifted 2.5" Lovells Leafs / Rear Auto Locker / LSD in front / 33x12.5x15 MT Achilles / 9500 RUNVA w plug n kills switch inside cab / EGT, Voltage, Turbo timer, Boost gauge / 20 PSI VF10 Turbo with VF10 exhaust housing 2.5" downpipe with merged 2" wastegate pipe to full 2.5" straight pipe / GFB Boost Tap / Maxed fuel with grinded down cable stop / Adjusted Boost Compensator / 3.1 Oil Cooler / Intercooled / 3" Custom intake to sealed K&N airbox & filter to Snorkel / Catch Can / Xtreme Outback HD clutch / 80 amp alt / RockfordFosgate 300rms AMP w 2X Rockford Power 6x9's BT HDeck / all EGR, QWS, AC pump deleted.

Re: 2 questions

Postby tonkamu » Fri Oct 05, 2018 8:26 pm

I can easily get over 30psi no problem and not bad egt's but been told vf10 can only handle 20psi.
tonkamu
Isuzu Senior
 
Posts: 156
Joined: Sun Jan 01, 2017 7:23 am
Age: 36
Country: NZ
City: Auckland
Vehicle: 2.8 Mu 1991 All Black. MODS - Rear Lifted 2.5" Lovells Leafs / Rear Auto Locker / LSD in front / 33x12.5x15 MT Achilles / 9500 RUNVA w plug n kills switch inside cab / EGT, Voltage, Turbo timer, Boost gauge / 20 PSI VF10 Turbo with VF10 exhaust housing 2.5" downpipe with merged 2" wastegate pipe to full 2.5" straight pipe / GFB Boost Tap / Maxed fuel with grinded down cable stop / Adjusted Boost Compensator / 3.1 Oil Cooler / Intercooled / 3" Custom intake to sealed K&N airbox & filter to Snorkel / Catch Can / Xtreme Outback HD clutch / 80 amp alt / RockfordFosgate 300rms AMP w 2X Rockford Power 6x9's BT HDeck / all EGR, QWS, AC pump deleted.

Re: 2 questions

Postby paulthepilot5 » Fri Oct 05, 2018 9:16 pm

I would be getting a boost gauge that covers the range you want to run. Probably not getting 200hp at 20psi Going off the feel is not a great indicator for hp. Dyno is the only way to know and accurate HP-torque figure. Given the higher flows you are dealing with probably worth going bigger but there won’t be a jaw dropping increase in power. I have been running 2.5 dump and exhaust on mine but want to also upsize to 3inch to chase every bit I can.
paulthepilot5
Isuzu Junior
 
Posts: 129
Joined: Thu Apr 05, 2018 8:56 pm
Age: 38
Country: Australia
City: Brisbane
Vehicle: 1995 Isuzu Rodeo 2.8d
Compound twin Turbo
12mm fuel Pump
+50 injectors
Water/meth injection

TF Rodeo ute 2WD short wheelbase
2.8 4JB1T
Inline injection pump conversion
+50 injectors
Borg Warner s200 turbo
300hp, 650nm

Re: 2 questions

Postby geeves » Sat Oct 06, 2018 6:26 am

The limitation in the turbo is the amount it can boost in one go efficiently. Someone else on the forum was building a twin turbo settup with the first turbo boosting 20 then the second taking this to just shy of 40 and he was expecting serious numbers. The engine is strong enough but once you are that far from standard everything you do affects something else. Above 20psi a 3 inch system makes sense maybe even a 4 inch but you may also find it cant flow any more gas as there isnt any to flow because your intake is restricted. Then once you have all that working the clutch starts slipping the cvs shatter every time you put it in 4wd and the driveshaft twists in half Fix all those and you find the brakes are not that great and the cooling system only just copes but your heater works well. Also if its leaf sprung axle tramp becomes an issue.
Everything is possible.
Sanding your knuckles before starting work can help. That way you cant skin them
User avatar
geeves
Site Admin
 
Posts: 8962
Joined: Sun May 10, 2009 1:36 pm
Location: Rangiora
Age: 63
Country: NZ
City: Rangiora
Vehicle: 94 bighorn 4jg2
2013 Subaru XV

Re: 2 questions

Postby SamMu93 » Tue Nov 27, 2018 6:37 pm

geeves wrote:The limitation in the turbo is the amount it can boost in one go efficiently. Someone else on the forum was building a twin turbo settup with the first turbo boosting 20 then the second taking this to just shy of 40 and he was expecting serious numbers. The engine is strong enough but once you are that far from standard everything you do affects something else. Above 20psi a 3 inch system makes sense maybe even a 4 inch but you may also find it cant flow any more gas as there isnt any to flow because your intake is restricted. Then once you have all that working the clutch starts slipping the cvs shatter every time you put it in 4wd and the driveshaft twists in half Fix all those and you find the brakes are not that great and the cooling system only just copes but your heater works well. Also if its leaf sprung axle tramp becomes an issue.
Everything is possible.


Haha I had a good laugh reading this Alan! :D
Always helpful advice
SamMu93
Isuzu Junior
 
Posts: 148
Joined: Sun Jan 18, 2015 3:22 pm
Age: 29
Country: New Zealand
City: Wellington
Vehicle: 93 Isuzu Mu 2.8 TD
Rodeo 3" dump pipe off turbo
2.5" Exhaust to tip
Bighorn intercooler
Tweaked fuel pump
Boost tap (15psi)
Egt monitor installed
Rear: 2" lifted leaf springs
Front: Wound torsion bars, dropped front diff, flipped ball joints, cut upper bump stop

Re: 2 questions

Postby dieselguy86 » Sun Dec 02, 2018 7:49 am

Im the one building the twin turbo, ive been busy with work so havent done much with the build. But you wont notice any performance going to 3” until around 250-300hp.
dieselguy86
Isuzu Baby
 
Posts: 45
Joined: Sat Jul 07, 2018 3:18 am
Age: 32
Country: USA
City: Republic
Vehicle: (2) 86 Trooper II diesels
(2) 86 Jeep cherokee diesels
06 chevy 2500 duramax
14 jeep grand cherokee ecodiesel

Re: 2 questions

Postby tonkamu » Sun Dec 02, 2018 11:21 am

Oh yeah, going to give it a try anyway. Planning to do 3 inch mild steel from my 2.5"/2" married downpipe to front of passenger side rear wheel, no baffle or silencers. Hopefully get some cool gear changing sounds like I had when I only had my downpipe on, no big long exhaust attached.
tonkamu
Isuzu Senior
 
Posts: 156
Joined: Sun Jan 01, 2017 7:23 am
Age: 36
Country: NZ
City: Auckland
Vehicle: 2.8 Mu 1991 All Black. MODS - Rear Lifted 2.5" Lovells Leafs / Rear Auto Locker / LSD in front / 33x12.5x15 MT Achilles / 9500 RUNVA w plug n kills switch inside cab / EGT, Voltage, Turbo timer, Boost gauge / 20 PSI VF10 Turbo with VF10 exhaust housing 2.5" downpipe with merged 2" wastegate pipe to full 2.5" straight pipe / GFB Boost Tap / Maxed fuel with grinded down cable stop / Adjusted Boost Compensator / 3.1 Oil Cooler / Intercooled / 3" Custom intake to sealed K&N airbox & filter to Snorkel / Catch Can / Xtreme Outback HD clutch / 80 amp alt / RockfordFosgate 300rms AMP w 2X Rockford Power 6x9's BT HDeck / all EGR, QWS, AC pump deleted.


Return to Engines and Exhaust

Who is online

Users browsing this forum: No registered users and 7 guests

cron