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Old 02-27-2011, 10:34 AM   #61
jgorm's Avatar
Join Date: May 2010
Location: San Diego
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Originally Posted by jb_sexton View Post
Route your exhaust underneath the oil pan from the stock manifold. Run it into your turbo, then run the exhaust out of the turbo, right back into your stock exhaust. Run an oil line from your pressure gauge and a return line right into the oil pan. There are a couple things i'm unsure of in my turbo. I'm not sure if I need to change my injectors and alter my computer. I won't know that until that time comes. All in all, I'll have WAY under $400 in a turbo and that includes purchasing the turbo (junk yard).
You could do this if you are skilled in making custom headers, or casting manifolds. The hot side if the tricky part of a turbo. I would install bigger injectors, fuel pump, and then tune the computer. If you are going through the trouble of adding a turbo, at least put 6 or 9 psi of boost in there. With the low compression the engine should take it fine (with 91+ octane). 9 psi will give you a 50%+ increase in power.

You don't need high tech stuff like overhead variable cams to make power. Look at the LS7. Good old pushrod 2v putting out 500+hp.

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Old 03-02-2011, 08:59 AM   #62
Join Date: Aug 2010
Posts: 36
Originally Posted by Beachmike1 View Post
The 2.5L engine produces about 120 HP design SAE net at the flywheel. This is at Sea level where the manifold pressure at wide open throttle is 14.7 psi or 29.92 inches of hg. 3 to 4 psi booots will require a cetain amount of exhaust back pressure to drive the turbo this from equations not to be quoted here is on the order of 10 hp to 15 hp if thing work well. This is NOT free is comes from reducing the exhaust efficieny but only by about half the amoutnstated above. ALso one must take into account that the maximum hp increase (if the porting and such can support the increased flow linearly, which without porting it cannot) will be a ratio of the new max manifold pressure devided by the std manifold pressure. In this case 4psi +14.7 all divided by 14.7 psi.Which is about 18.7 / 14.7 or 26.7% or maximum power improvement of 32 hp. However that is assuming the porting can support this and that the drag fromt the turbo not significant. realistically think more like 22 to 25 hp. Remeber the combustion chamber is NOT desgned for the increased pressure so a lower ing oft he CR would be prudent to prevent detonation. so you may be looking at more like a 20 hp increase or 140 hp total.

Itr would cost less to seel the 4 cly jeep and buy a 6
Porting the Heads would help dramatically in over all power and air flow.
Aftermarket Aluminum Intake, and a bigger lift cam for the exhaust valve, and maybe .100 of duration on the exhaust and intake would dramatically improve power.
And for highway speeds you would want torque, so maybe aftermarket stroker crankshaft.
Thats where the turbo would come in to play.
You may have a bigger stroke but the engine should actually be faster because of the turbo.
If you plan on upgrading the little 4-banger to get some good quality reliable power, then your going to have to spend some money.
instead of spending 4,000$ on a turbo and 2,000$ on exhaust, cam, air filter, intake, throttle body, fuel injectors, spark plugs, crank..
Not to mention the new transmission and rear-end you will need, because the factory dana 35 rear-end has some pussy spider gears.. beleive me.. they will break.. and it wont take long..
Heres an idea that solves everyones problems about power for cheap..
go to a junk yard and find an old monte carlo, take out the rear end, 7 1/2in. and go find a 3 speed automatic.
Keep the front wheel drive transfer case, and then call a GM dealership near you, and ask for a 602 crate engine, 350hp and 400ft-lbs of torque, or the 604 crate engine, with a bigger cam ,and ported heads with 400hp and 425ft-lbs of torque.
id keep get a bigger rear end if you get the 604, and big tires would destroy it in a heart beat.
Problem solved. All for around maybe 4k maybe 4,500$

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