4.0 tear down after miles of boost

[Gui]

i was thinking of doing the same to my 92 ranger 4.0 and see if i could bypass the maf and run 5psi. i got a hks standard wastegate with 5 psi spring from bro's friend and a garrett t25 turbo from a saab 93. lol my bro kinda talked me into it when we were working on his nuty rx7 3rd gen project

 

[Wicked_Sludge]

why on earth would you want to bypass your MAF sensor?

and turbo cat, where are you getting those numbers? 6x 19# injectors wont even support 200HP at a rather anemic .5 BSFC (which i doubt your running boosted) with stock fuel pressure. even if you bumped the FP up to 60 PSI youd be pushing the limits again at 220HP....in fact, 19# injectors @ 60 PSI would probably be just about right for 5psi of boost (not the 12-13psi it takes to lay down 300HP).

tuning through the PCM isnt going to do you much for overall fuel flow. ford sets their injectors max duty cycle at 80%...if you were to electronically increase it much beyond that you'd start having injector reliability problems as the coils heated up. even if you did, at 100% duty cycle (static) the stock injectors would only support just over 200HP on stock fuel pressure.

 

[Will]

I think the BBK supercharger kits were about 5psi and used the stock injectors with the fuel pressure booster thingy. I believe they claimed 220hp--+60hp. Adding 10# of fuel pressure adds about 2# /hr to the flow rate so a 19# injector will be a 21# injector and that will support 200hp. A 21# injector would become a 23# injector with another 10psi behind it and will support 220hp. I don't know how high you could boost the pressure--probably 25psi as I've seen some cars that ran stock with 60psi on the rail.

 

[turbo cat]

at 5 psi my sotkc motor is probally barely seeing maybe 200 hp. its not even the power is the torque curve that may look nice wit ha smaller turbine housing. The turbo i have has a .48 ar housing which is too small for upper range power on a 4.0. The goal is torqyue anyways so i dont eve3n have to rev high to make acceleration/towing power. Anyways its all slapped back together here a quick video i may have given it about 50-75% throtle and shifting early.



and GUI dont bypass the maf...pull thru the MAF. unless your going to convert ot a speed density efi and run a MAP

 

[Wicked_Sludge]

5 PSI is 5 PSI. when your at about 5,000 RPM at WOT, what PSI is it running (assuming you have a pressure guage).

5 PSI on a 160 HP engine should be at least 200HP, if not a little over.

 

[turbo cat]

I rarely even see 5K as it is. The 4.0 is not a high rever. I doubt im making 200hp actually. a bigger turbo maybe thats doable or better. 5 psi is not 5 psi. boost is a measure of restriction. On a bone stock 4.0 5 psi is only going to help so much when untuned. The main thing is the small turbione housing is probally choking the motor out at aqnything above 4k. i would be suprised if its not and maybe when i get the time someday ill test the backpressure before the turbine. Once i get MSII tuning woulnt be a problem but for now im just running 21#ers on a stock ecu. i have no reason to turn up the boost above 5 psi for a while as i have no need to keep changing HGs or broken parts. I want to keep it alive so i can focus on turning it up on the cougar. Im building a new turbo kit for the car and lots of attention in the body and suspension is needed on the car as well. For now im just going top leave the boost controller open and daily drive it. even if i do make 230hp @ 5K i rarley would be there for long.

 

[Wicked_Sludge]

The main thing is the small turbione housing is probally choking the motor out at aqnything above 4k.

ok, then what boost does it produce at 4K @ WOT? if your still in the boost then, your turbo isnt restricting the engine. if your drawing a vacuum, THEN your trying to pull more air than the turbo can push...but i seriously doubt thats the case.

 

[turbo cat]

just because you see 5 psi on the guage dosent mean the housing is still choking the motor out. I would have to test the backpressure however and check the compressor map over. I may not be choking the motor but either way with the truck not being tuned i doubt im making 200. im willing to bet i may be making a very nice torque number buta horrible power number. Omar over at RPS has a larger turbo on his 4.0 ohv and only a aftermarket cam. At 14psi omar made just over 300hp and almost 400 ftlbs of torque and tuned with a stand alone. At 5 psi untuned i highly doubt ill see above 200 at the flywheel. Smaller than needed turbos per application generallly show a huge torque number however a pittiful power number. higher backpressure will keep the turbo spinning fast but if the turbine is too small the backpressure will escalate too high too really see some large gains. If it gets too high the reversion will be bad enought to escalate egts which if goes high enough can melt valves/ pistons and or cause detonation.....

 

[Gui]

no yeah i was thinking about it lol im might not becauuse i thought you had to convert to map sensor??

 

[Wicked_Sludge]

theres no reason to convert to MAP. a MAF system can be tuned to anything (in the case of EEC-IV, usually more than) a speed density system can.

 

[turbo cat]

no yeah i was thinking about it lol im might not becauuse i thought you had to convert to map sensor??

You could look into speed density aftermarket stand alone systems. They would be the best route to go. However there not a plug and play thing. A map sensor does a better job in a turbocharged setup but a maf can handle the task. The maf measures airflow. The map reads vaccum/pressure which and you woulnt have the restriction of the maf and pegging problems.

 

[Davis]

If you get the right MAF, neither restriction nor pegging are a problem.
http://www.vmptuning.com/store/index.php?p=product&id=193&parent=30

 

[fixizin]

Omar over at RPS has a larger turbo on his 4.0 ohv and only a aftermarket cam. At 14psi omar made just over 300hp and almost 400 ftlbs of torque and tuned with a stand alone.

OMG!... if I had even 300 ft-lbs @ the rear wheels, I'd be driving around with a woody all day, LOL!

 

[turbo cat]

The turbocharged hit is also something else. When the boost comes on quick it makes for a fun ride

 

[CopyKat]

The one thing with a small turbo is that there is no lag. If you were to put a larger turbo on you will get wicked lag and once you get boost you'll break the tires loose. My brother-in-law's 280 will break the tires loose at 75 Mph if he romps on it. As far as I can tell he's got no lag and hes running a 6.0L powerstroke turbo on his 2.8L. I think I'll be in good hands with my project.

T-cat how did you boost your fuel pressure? another pump or are you running stock pressure with 21 lb injectors.