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new guy wants to turbo 242 4.0l amc! need some questions answered.

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new guy wants to turbo 242 4.0l amc! need some questions answered.

Old 12-12-2012, 10:27 PM
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Join Date: Dec 2012
Posts: 1
Default new guy wants to turbo 242 4.0l amc! need some questions answered.

hello i want to build a turbo system for my jeep xj. i know every one is going to be like use the search. but no one has answered what i need!

one how much doe it cost or how much did your budget built cost?
power increase?
did it improve the mpg?
how much psi can a stock 4.0l take?
do i need to do new head stud take?
how much compression does the motor need to be able to turbo, like how many miles on it is it safe to turbo, i dont know how many miles so i figured i can do a leak down test or compression check to see if its safe to turbo.
how did you tune the ecu to run right?

i really dont know what it takes to turbo i would like some help and im hoping that i dont need to rebuild my motor cause i want to do it on a budget. thanks much tyler
tyman729 is offline  
Old 12-21-2012, 03:27 PM
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Join Date: Oct 2009
Location: CHICAGO
Posts: 934

this site doesnt rude people buy saying do a search.... welcome!

building a turbo kit can be affordable but only if your capable of doing it all yourself. if you have to outsource work then it gets pricey. if built many turbo vehicles with the cheap ebay parts kits for ~1500.00 or less(this is me doing all the fab). if you want to go quality parts then a good used quality garret, turbonetics, holset, ihi or mitsubishi turbo is going to cost between 500.00-750.00, quality wastegate(if turbo doesnt have an internal wastegate) 150.00+, custom tune 500.00 or more.

power increase depends on engine but a rule of thumb is 10 hp for every 1 psi boost

mpg will stay the same when boost is not present(ex: cruising down the highway). once boost is present then kiss mpg goodbye. this is what makes it addicting.......

a rule of thumb for boosting a stock n/a engine is 10 psi or less. most engines can handle this much.

no engine modification is needed if you keep the boost to 10 psi or less.

a n/a engine has higher compression than a factory boosted engine. this is what limits your boost pressure on a n/a engine unless you build the engine internals for boost over 10 psi. engine mileage doesnt matter as long as your engine is healthy

tuning is the hardest and most expensive part as most people cant do it. you will need to call performance tuning shops to see if your computer can be tuned by someone near you.
busa4 is offline  
Old 01-01-2013, 10:09 AM
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Join Date: Jan 2013
Posts: 3

all exactly true, i have a turboed comanche so i figured i would add a bit to it. i have about 1k in my build but i can weld and fab where needed. as far as jeeps go they love boost. they are 8.2 or 8.4 to 1 compression and as long as the motor is healthy mileage doesnt matter i have 300k on mine with no issues. mpg actually increased while cruising, the flow if the heads arent the greatest so just cruising the air flows better with the turbo instead of being sucked in if that makes sense. from your info in the left it says its a 92 so if thats the case the factory computers are easy to work with. i put a set of 24lb injectors from a 5.9 ram, direct fit and a fuel pressure regulator. the map sensor accepts boost. factory readings only go to 4.5 volts, under boost it goes up to 5.0volts and the computer is fine with it. on the dyno and street the air/fuels were low to mid 11s under boost. im only running 6psi and have been for 5 years now. if your wanted to mess with timing a simple msd btm would be perfect. hope this helps, if you have any more questions hit me up.
turbojeeper is offline  
Old 01-05-2013, 07:17 PM
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Join Date: Jan 2013
Location: Mexico
Posts: 3

As turbojeeper and the rest say you can do it as long as you're willing to do most of the job. The knowledge you will get is priceless! Since you'll have to gather all the pieces by yourself (injectors, fuel pump, sensors, etc) sooner or later you will have to do some math (calculate injector size, pump capacity, etc). Fortunately there's a calculator to do this for you in the form of an App for your smartphone. Just went through an EFI retrofit and it was of enormous help, believe me. It also contains basic info about EFI components and some tuning tips.

If you're of the apple crowd look here:


else if you like the Android devices go here:

brickyenne is offline  
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