I've been watching this forum for years, but never commenting on the turbo bits, because, well, I haven't ever really wanted to before.

However, in this case, my question is for those who have turbo'd engines before and have some time on them. What has been the results of your exhaust to turbo setup? What did you do and how well has it held up?

My interest is in durability, not ultimate performance. I'm only looking to get 150 to 170 horsepower at most, and all at or below 4000 rpm, so this isn't a high flow, high boost thing. Rather, it would go in a truck, and durability is vastly more important than ultimate power.

I would expect to use a turbo from a 2.2/2.5 chrysler, wastegated to about 4.5 to 7 psi. I want low end grunt, not horsepower.

If you had manifold failure, what failed and why?

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'81 W150 on Propane... Oversize valves, Oregon Camshaft cam, 10:5 static CR, Distributorless ignition, megajolt timing controller, PowerTrax lockers.

since no one else is posting ill get it started.

ive been running my setup for a season now. using the j-pipe. working well so far. definitely not a limiting factor in my setup yet.

if you are only looking for that amount of power you should be able to get it out of an N/A slant pretty easily.

the 2.2/2.5 turbo would give you low end but it would kill any and all top end it would run out of steam very quick and take away your ability to rev over 4k if it even gets there. that would take away anything over 70mph including passing on the highway. a grand national turbo is sized about right and will give you the low end you are looking for and not limit your ability to rev.

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1966 Plymouth Valiant, 225, 3 on the tree, 8 1/4 3.21 sure grip, hyperpac, holley 650dp, holset h1c

Make sure your pipes and flanges are very thick and you should be OK w/durability. Use gaskets with stainless sealing rings, not copper. I have used several SCE copper flange gaskets and they overheat over time and get soft and start to leak.

Hard to tell what you are planning. Is this a stock exh man with a J-pipe?

Lou

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Home of Slant6-powered fun machines since 1988

Well, that's kind of the question. The J-pipe thing seems easy and cheap, but it also seems to be a bit fragile and short lived, especially in a truck that would spend a lot of time on rough road / jeep trails / no roads and towing things.

That's a lot of stress to throw on that 2 bolt flange, it seems to me.

That's why I'm asking what people have done and how it has worked out in the long run.

The turbo in a mopar 2.5 had no trouble at all pushing 175 hp, though it was getting a little small. However, it spooled like instant, and they're easy to find and cheap. And, as far as getting 170 hp from a slant, yes, you can. But won't have any grunt at all just off idle and towing would suck, due to needing to buzz the thing like crazy. This engine will remain propane fueled (my /6 is dedicated propane now, with distributorless ignition and head built precisely for propane) and I just want to go back to the stock cam (or close approximation thereof) and and have some extra oomph mid-range.

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'81 W150 on Propane... Oversize valves, Oregon Camshaft cam, 10:5 static CR, Distributorless ignition, megajolt timing controller, PowerTrax lockers.

i braced my turbo. i was afraid of the j-pipe cracking or other. it doesnt move what so ever. i built it so that the total weight of the turbo could be held by the brace without the pipe in there. here in nj driving down the road might as well be like tearing through a field. the surfaces are horrible. patch and pray has been the method for keeping up with the roads around here for as long as i can remember.

the little turbo on a 2.5 is sized for a 2.5. same turbo on a 3.7 is not gonna have the same effect. it would spool almost instantly but just off idle its going to be pushing hot air and running out of steam pretty quickly. you could achieve the same spool time with a slightly larger t3/t4 turbo with a small turbine housing. (you would essentially be running the same hot side as the 2.5 turbo but the cold side matched for the slant. you get the quick spool and the higher pressure ration needed to let the slant breath). but it would benifit by pushing cooler air and wouldnt hold the engine back or run out of steam quite as fast if you keep the boost low.

Actually, it's all about the CFM, and horsepower and cfm are intrinsically related. Thus, for rough approximation, a 150 horse 2 liter and a 150 horse 4 liter will work out just fine. Most people who turbo a slant are not after 1200 rpm stump pulling power, they wanna accelerate and wind a few revs to get some horsepower. I want power in the 1500 to 3500 range and not get short of breath of 11,000 feet.

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'81 W150 on Propane... Oversize valves, Oregon Camshaft cam, 10:5 static CR, Distributorless ignition, megajolt timing controller, PowerTrax lockers.

While I'm on the topic, has anyone ever built a different intake that would work a bit better with a turbo?

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'81 W150 on Propane... Oversize valves, Oregon Camshaft cam, 10:5 static CR, Distributorless ignition, megajolt timing controller, PowerTrax lockers.

i get what you are saying but with a turbo that small, without a rear end ratio somewhere in the 2.xx's you will struggle to do freeway speeds.

Why?

Engine CFM calculators tell me that my old 2.5 to make 170 net hp pushed about 325 CFM at 5000 rpm. Now, mind you, the little mitsu turbo was wheezing a little by 5500 and losing power rapidly at 8 psi - then again, the 2.5 did flow a little better than the slant, both intake and exhaust. At 12 PSI, it was obvious it was undersized at about 5000, but weight vs 1/4 mile speed indicated I had about 170 hp to the ground.

But, it was perfect for the vehicle it was in (Caravan).

A slant six, running at 5 psi boost, at 3750, is absolutely the same CFM requirements as the 2.5 at 5000 at WOT. And, it says 215 engine hp - about 170 after normal adjustments.

Or, in other words, not a problem at all - especially since my target is 150, not 170 hp.

The old 2.5 spooled well at 1800, the slant will spool well at about 1200.

It will run very nicely, and with 4.56 gears, 32 inch tires, and a .79 overdrive, it's 2600 rpm at 65 mph.

Really, I just can't see why anyone thinks this is a bad combo.

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'81 W150 on Propane... Oversize valves, Oregon Camshaft cam, 10:5 static CR, Distributorless ignition, megajolt timing controller, PowerTrax lockers.

150 horses? A stock slant makes 145. Or are you talking at the wheels?

At the wheels I'm told it's lucky to have 95hp. I turbod mine and with an ignition that failed in the higher RPM, I only made 164hp/234'lbs of torque @3700RPM and 8pounds boost.

I have since fixed the ignition and it goes over 4k now and will take it back for another dyno pull when I'm done with a few other things.

But if you're going for 5psi I'd say 150-160 is a reasonable amount at the wheels i think.

More like at the wheels.

My slant, using a program and a phone with an accelerometer, claims about 90 hp. It runs on propane, has a little bigger cam than stock, has true 10.5:1 compression, distributorless ignition...

And, sadly, it's parked in eastern Washington for a few years, until I get the chance to move back west from Illinois. I'm not bringing an 81 here to rust.

This is the truck:

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'81 W150 on Propane... Oversize valves, Oregon Camshaft cam, 10:5 static CR, Distributorless ignition, megajolt timing controller, PowerTrax lockers.

A couple things to take into account on your calcs...
Don't forget that unless your A-500/A-518 is over 50-55 mph, the convertor will not be in lock up...so at rpm/speed under that you need to have an 8% slippage allowance....I can also say that the 5.2 magnum with the A-518 4x4 in 2wd mode in a Ramcharger is OK, but I knew my power and mpg were going out the window on a daily commute and more could have been had out of the combination (and even off the road in the high desert it was "doggy"). The only truly "locked" transmission in all gears is going to be a manual tranny...then you just have to worry about the clutch going...

I would not worry about the HP, I would do all my calcs for torque only...that is the hardest thing to improve on the already flat moderate torque curve slant six...typically if you design for all torque the HP curve lands in the realm you are looking at on NA engines. I have never sacrificed my torque for top end and have had better low end than stock engines, but you have to work with your cam choice/phasing, compression, tranny and rear ratios. Remember that torque is launch and how much you can move...HP is the top end or ability to do the work...

About 12 years ago I pulled a bunch of NP435 powertrain parts for a board member who is not on here any more, he was building a hunting rig Ramcharger, super six, 9:1 compression, Comp 252 cam, 4.11 gears, smaller tires than you are looking at and the NP435 married 4x4 system with 11" clutch...I know he got it all together and the thing was not "fast" but it could crawl some steep terrain pretty well.(forgot to ask him how he modded the BBD to take the angles without emptying the bowl or stalling out).

Good luck on the build.

I currently have an np435. and I'm not going to a 500 or 518, my target transmission is a Getrag 238 six speed. It would require changing over to the hydraulic clutch - which is mostly a little work on the firewall and bolt in. The ramchargercentral guys know all about it. It should bolt to my NP208 or get a somewhat newer (late 80's early 90's) np241. It will also require a shift lever mount.

The ratios are:

4.23, 2.53, 1.67, 1.23,1, and .79.

Nice close ratios. In 2nd through 6th, if you shift at 3000, your next gear is above 2000. It appears to only require a v8-slant 6 bolt pattern adapter, a little tweaking on the floor hump and moving the transfer case a little and probably adjusting the drive shaft lengths.

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'81 W150 on Propane... Oversize valves, Oregon Camshaft cam, 10:5 static CR, Distributorless ignition, megajolt timing controller, PowerTrax lockers.

That makes more sense, although the RPM on the upshift may plummet more due to vehicle weight and profile, it should be fairly close to your calc.

Since the Getrag is for the LA engine, I also figure you're going to use an LA flywheel and egg out one hole so it all fits up correctly, although it's too bad you can't just use an adaptor on the NP bellhousing and keep the bigger clutch and swap fewer parts.

I'll keep watching this one, take pics so you can add an article once it's all in and shook down.