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4.0 ohv turbo hotsides


turbo cat

Well-Known Member
Joined
Aug 10, 2008
Messages
629
City
city of rain wa
Vehicle Year
91
Transmission
Manual
I have been designing a turbo hotside for the 4.0 ohv. It will use the oem cast iron manifolds and be setup for a chrysler style T3 turbo which can regularly be found everywhere. Just getting an idea if anyone is interested. They will be constucted of mild steel and mig welds.
 
Hotside is the exhaust componets between the heads and turbo. Basically I will be fabricating a Y pipe that will bolt the turbo to the manifolds. The downpipe will be the exhaust behind the turbine outlet. The hotside will alow you to bolt a T3 turbo to a 4.0. You would still need a downpipe fabricated, intake plumbing, bov, oil lines...The exhaust part is the hardest part for most who dont have access to a welder or experience...Plumbing oil lines, running intake plumbing and so on are the easy parts.
 
Dont limit yourself to just te dodge T3 pattern on the turbo flange, you should also put a Standard T3 pattern on there as well.
 
A standard T3 flange should fit a chrysler flange with the drilling out of one hole. The turbo dodge guys have been bolting standard T3 housings to there cars for years. Since I am also going to be cutting out the flanges myself I many look into leaving extra meat should someone want to bolt on a T4 however a T4 is pretty unnecessary on an ohv. I agree 100% a .68ar turbine housing on a 4.0 would be 10x better but the chrysler T3s are easier to come by.
 
Just a little progress here. As you can see in the second pics that is part of the current old kit under the jig.
DSC01942.jpg

DSC01962.jpg
 
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I question your turbo sizing. The 2.2L and 2.5L dodge turbos were small for the 4 cylinders they came on. Two of the really small mits 2.5L turbos would work very nice on a 4.0L in a twin turbo setup. The 4.0L almost makes twice as much HP as the N/A dodge and about the same power as the turbo dodge 4 cyl. That turbo is just WAY to small. Plot that on a turbo map, the result is insane back pressure, very high intake temps (very low efficency) and nasty EGT's.
 
I do agree it is undersized...for a reason. The reason its setup for a T3 turbo is minimal lag. I have used a single chrysler T3 for 2 years now. This kit gets you started. Not to mention you should be able to adapt a standard larger T3 to the flange (yet to be tested). Its also not that hard to build an adapter plate to adapt various turbine housings. The 4.0 dosen't rev very high and dosen't make that much power but it does make good low rpm torque and full bosot before 2K compliments that torque curve. However I will also be testing temps and backpressure levels. For low boost the chrysler T3 has served me well for a while now even when my current setup is far from great as its not even intercooled or properly tuned. ALso the chrylser t3 is not as restrictive as you would entirly think as the turbododge guys commonly crank these turbos to force 14+lbs into thier intakes. I'm fine with 5lbs on a bigger engine that rarely sees above 4000
 
Fabricating and installing a decent turbo system requires a fair amount of time and effort, choosing the right turbo makes that time and effort worth it. If your 5 psi of boost on a 4.0L is only making 155 RWHP I personally would not consider that best return on the effort. I am sure the torque down low is noticable and it feels good, but you have only managed to take the engines stock flywheel HP numbers and make that at the rear wheels. You might be 200hp at the flywheel. With stock HP numbers around 160hp at the flywheel that is about a 20% increase in HP, with the best part being a noticable jump in bottom end torque. With that said if your time is free to you and your making cheap parts work, and it has worked for 2 years without blowing up stuff, then good job. But the saleable value of that hotside is probably much higher if you had another 20-30hp with the same safe 5 psi boost by just picking the right turbo (for your "protype" vehicle). A TO4 57 tim or a used Grand national turbo with the proper hotside A/R ratio could still spool by 2000 RPM and at least let the motor make power to its stock 4500 RPM happy land.
 
Lack in power probally had more to do with lack of intercooler. No tuning equiptment just fuel pressure with a phat 10-11 AFR. 5 lbs making only 155rwhp isnt toooo bad considering what I have said above not to mention this was on a unkown milaged used 92 motor with clattering worn pushrods thru a 4wd drivetrain. The old kit was also not the best flowing kit it was cobbled together in a day and put on the road. I don't need 300hp on my specific vehicle all I wanted was a strang torque curve and I got that. The chrysler T3 suits me just fine where did you not get that? The kit Im building will allow you also to bolt on a larger T3 and various other turbochargers with slight modification. SO if someone wants to bolt on a larger unit or "more effecient unit" they can. The kit will also be pretty affordable allowing the budget guy to get it up and running on the cheap. There have been guys making 200rwhp with m90s on a 2wd chassis with corect tuning mods....So 155 with all that I had wasnt actually all that bad. This was also on a mustang dyno. Once i have the new kit built I will be installing an intercooler and hopefully better tuning equiptment and heading back to the dyno.

why not buy a remote mount turbo kit?

Remote kits work but I don't like em. WHy? A noisy scavenge pump that can fail at any time.
 
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I think the point is that while it may have worked for what you wanted it to do, there are not going to be many customers that see it the way you do. Why not just make it set up for a standard t3 and if somebody wants to use the tiny chrysler t3, let them adapt it?
 
I think the point is that while it may have worked for what you wanted it to do, there are not going to be many customers that see it the way you do. Why not just make it set up for a standard t3 and if somebody wants to use the tiny chrysler t3, let them adapt it?


Actually theres already been alot of people who have been interested for the same purpose. A standard T3 flange has a rectangular bolt pattern. The chrysler pattern has the same pattern minus one offset bolt hole that is inward on the flange. Mounting a standard T3 is as easy as a drill and a drill bit. I will also be looking around for a nice standard T3 to make sure it clears :icon_thumby: This isnt about money to me I am barely going to make anything off of these so if someone dosen't like it they don't have to buy one.
 
I don't really want to pick on you, but when you move from trying to coble something together something from the junk you have laying around, to selling parts to someone else you open yourself up for examination.

The only reason why you might need an intercooler at 5 psi boost is you air temps are super heated by the wrong size turbo. The fact that the motor is tired (likely a little oil fouling) and your air temps are high means that your already close to detonating a 9 to 1 compression motor at 5 psi. The fact that your AFR is pig rich at 10-11 AFR is probably saving you. I doubt you will gain much power by an intercooler or a leaner AFR. Considering your exhaust backpressure is likely over 10 psi it gets really hard to make HP, the biggest cork in your system right now is the less than 1" diameter hole in the hot side of that turbo your supporting.

I am not against making crap work, years ago my first turbo project was a stock 5.0L that we stuck 2 2.3L turbos on and hacked up an intercooler off a kenworth. It was all hacked up piping, hardware store crap boost plumbing and flipped headers etc. But that motor made over 400hp at 10 psi boost, up from a stock baseline of 225. It came on boost quick and would break the radials loose at 60 MPH. There was not much money at all in that job, but it made power because it had the right parts in the right spot. It was a rusted old 81 mustang and it ran fast enough to get in trouble for no roll bar (11.50).

You don't have to listen to me or others who have already told you your turbo is to small, but don't tell someone else that they should make the same mistake. Your flange choice on your hotside kit is suggesting that.
 
I don't really want to pick on you, but when you move from trying to coble something together something from the junk you have laying around, to selling parts to someone else you open yourself up for examination.

The only reason why you might need an intercooler at 5 psi boost is you air temps are super heated by the wrong size turbo. The fact that the motor is tired (likely a little oil fouling) and your air temps are high means that your already close to detonating a 9 to 1 compression motor at 5 psi. The fact that your AFR is pig rich at 10-11 AFR is probably saving you. I doubt you will gain much power by an intercooler or a leaner AFR. Considering your exhaust backpressure is likely over 10 psi it gets really hard to make HP, the biggest cork in your system right now is the less than 1" diameter hole in the hot side of that turbo your supporting.

I am not against making crap work, years ago my first turbo project was a stock 5.0L that we stuck 2 2.3L turbos on and hacked up an intercooler off a kenworth. It was all hacked up piping, hardware store crap boost plumbing and flipped headers etc. But that motor made over 400hp at 10 psi boost, up from a stock baseline of 225. It came on boost quick and would break the radials loose at 60 MPH. There was not much money at all in that job, but it made power because it had the right parts in the right spot. It was a rusted old 81 mustang and it ran fast enough to get in trouble for no roll bar (11.50).

You don't have to listen to me or others who have already told you your turbo is to small, but don't tell someone else that they should make the same mistake. Your flange choice on your hotside kit is suggesting that.

+1 your leaving alot of things out.. most people dont know how to tune a vehicle or set-up a turbo system... your leaving this open for people to run 5 psi wat some people dont realize a 5 psi waste gate is not factory really most spiked at 6 or 6.3... even then how will some one that has no clue figure out the rite waste gate... external you say well in fact the first time you spool up an external they spike un godly amounts mine hit 17 psi... on a 4.0 that would be devistating... then if some poor kid does do this and gets pissed off they can come to this thread and say "well look he said all i need is the part he sent a dodge turbo and some oil lines and exhaust with my fuel pressure fine tuned and i will be ok" then boom the boost spikes motor blows and your in the shit house.... not raggin just saying you dont have your 4.0 tuned in rite so how can you sell a kit to boost other 4.0s when you dont have the necessary tuning or specs for tuning... you can just say well set you FPR here and you should be good... before you put a turbo kit on the market and say here you have to have all the info the customer needs in order to get it done rite and not hurt nothing.... its called customer satisfaction ...
 

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