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Turbo choice help

W

Wesdunns70t5m

Member
Joined
Oct 4, 2016
Location
Fort Smith Arkansas
Greetings all, I am getting my new to me 1991 740 pretty close to being road ready, with a never ending future mod list. I have a few turbo decisions to make, and figured I'd call in to the experts here for some help!

I am not planning any turbo swaps tomorrow, but am gathering some parts, and want to drive the car as is, fix what needs fixed, and after I have some confidence in it I will consider a bigger turbo.

Here are my options, mainly because I already have some parts for either direction. The car is running a stock turbo on stock boost right now and has close to 300k miles. Either way, I will be planning to build another motor just in case this one craps out.

Option 1. I have a 16t turbo that has been converted to a 19t. It's not a true 19t, but I'd installed the 19t conversion from ardideas (no longer in business) wheel and compressor housing. I'd also had a turbine wheel upgrade, but can't remember the specifics there. The turbo is already bolted to a 90+manifold with kinugawa braided lines and do88 silicone hoses. I'd rebuilt the turbo maybe 30k miles ago, and have ran this on previous setups. All in it is a perfect turbo for daily driving, but I feel I would get bored rather quickly

Option 2. Is an hx35w turbo. I'd just pulled it from a junkyard and it spins freely,has minimal shaft play, and doesn't seem like it was leaking any oil. Problem with this turbo really just boils down to my current setup. It's got a twin scroll housing is another issue. I am running stock unported manifolds, with a stock head with the exception of an IPD camshaft. I do not want to mill out the center divided to turn it into a single scroll.

With the hx35w, I know it will be laggy, but that's where my question comes in. What would be a less laggy setup, getting a twin scroll manifold (probably the kangaroo teams one), or a single scroll housing in .63? The manifold would probably cost like double the housing, but something tells me that it would be the less laggy setup.

Option 3 would be to sell the hx35w,and use that money for an hy35. Still absolutely an option, I may be able to get back to the junkyard I got the hx from, and maybe find an hy and be able to swap them out. I'm just not sure how much potential I would be missing out on that way, or if the difference between an hy35 and a 19t would be worth loosing the low end power.

More than likely I'll end up installing the 19t, and getting some other bits over time for a bigger turbo. I've got some of those group buy oversized valves, so maybe some headwork and get those installed and possibly a twin scroll manifold. Just have to see how it all goes
 
I will go against the typical TB answer of 300hp. Yeah, it would be cool to say I've got 300, but power numbers arent a milestone to me. When I was running my 19t before I was pushing around 20psi, with a completely gutted interior. No idea how much power I was making, but it proved a very fun car. If the car was destined for daily duty, the 19t would definitely be what I'd run. With life the way it is now, I drive my personal vehicles less than 5k miles a year combined, so I definitely have some driveability to sacrifice.

The 19t is the biggest turbo I've ever ran on a car (laughable, I know). I really kind of want to experience a big turbo car. Never even ridden in one. As fun as the 19t was, I could definitely see myself enjoying a bigger, laggier setup. This will be a predominantly street driven car, no autox or drag racing or anything like that. With how little I will actually be driving the car,I can see me dealing with SOME lag. I'd like more power than the 19t provided (though it was honestly more than enough for any passengers I'd ever had). I don't want to wait until 4k rpms or higher for the boost to hit. If it's not spooling until then, I'd probably go full build and maybe turn it into more.of a toy than just a regular street car, but that's not what I'm after. If that's what I wanted out of the car, it would be getting an LS swap

I am really hoping to be able to swap this hx out for an hy35. From everything I've read, that would be a much better turbo for what I want and already have. I am really just trying to be prepared in case that doesn't work out for whatever reason.
 
what kinda transmission plans ya got? how high do you want to spin the engine?
 
In the not so distant future, but before any turbo swaps I will do the accumulator mod, and possibly a trans fluid cooler as well. I know it's questionable how long an AW will last above with any of these turbo choices really.

Without doing any headwork I'll be running whatever my chips are set at. I'm sure by the time I get turbos swapped and heads worked over I'll be ready to go ems on it and be able to play with it some more and raise the redline some
 
I've run a 15g, 19t, and one of the holsets on my car. IMO, the 19t has been the best as it has great spool, and will pull boost to redline no problem. I'm still only running 15psi. The holset is great if you want like... comedy turbo stuff. But imo it's fairly useless in terms of actual usability.

Even with my 19t I can still choose to do comedy turbo stuff (I run a hks ssqv for lolz and a side exit exhaust). Highly recommend. Can keep up with WRXs just fine (not from a dig).
 
Sorry, to add. My AW70 didn't love the 15g, but it was ok with it. I ended up shimming it (or whatever, blocking the valves... sorry, it's been a while) but then at some point the combo of the holset or the 19t started making it mad. Car is T5 now. If you're going to go turbo, you should just shim your auto right away or your car will melt.
 
EivlEvo said:
Sorry, to add. My AW70 didn't love the 15g, but it was ok with it. I ended up shimming it (or whatever, blocking the valves... sorry, it's been a while) but then at some point the combo of the holset or the 19t started making it mad. Car is T5 now. If you're going to go turbo, you should just shim your auto right away or your car will melt.
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Hopefully mine will hold up to a bit more, I've got the aw71 (or so it the 71L?). Whatever came on these cars that were turbo from the factory. I'm not doing a +t, it's already a b230ft.

I do agree though, the 19t is about a perfect turbo for these. I've ran mine on a couple bricks and absolutely loved it. I'm just stuck in the rabbit hole. The 19t is an all around excellent performer, and installation is as easy as it gets. But unfortunately in the quest for mo powah, it does become a bottleneck I believe

Once I get everything installed and the car lined out with everything I already have for it, I'm thinking the next logical move would be headwork, followed by forged rods. I feel like at that point, I'd be leaving a lot of useable motor on the table using a 19t that can't really utilize everything
 
I feel like the head is the limiting factor on these cars. I went down the rabbit hole myself years ago, and ultimately just decided to build with bolt ons until it blew up. But it hasn't. I have some ebay ic, ipd cam, 3"amm, some terrible injectors that make the car run like garbage on/off the iacv. IDK, a bunch of other crap. Once you get into head work you have to ask yourself if you really love the tractor motor, because for the money you'll put into the head, I think there are better motors for even less effort. The hell do I know though. Of my 6, 4 are up on stands rn.

Go forth and assplode motors.
 
EivlEvo said:
I feel like the head is the limiting factor on these cars. I went down the rabbit hole myself years ago, and ultimately just decided to build with bolt ons until it blew up. But it hasn't. I have some ebay ic, ipd cam, 3"amm, some terrible injectors that make the car run like garbage on/off the iacv. IDK, a bunch of other crap. Once you get into head work you have to ask yourself if you really love the tractor motor, because for the money you'll put into the head, I think there are better motors for even less effort. The hell do I know though. Of my 6, 4 are up on stands rn.

Go forth and assplode motors.
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I can understand that perspective. Because the value per dollar does get lower. However, having experienced the improvements with a professionally flowed head on stock valves. It gave me the smile factor that made it worth it. Made more power and ran smoother at all rpms. The high rpm airflow limit was raised. If I recall it was to about 7300 rpm according to my machine shop.

You are correct that the 8v head isn't the best for flow but it's damn good after some work. It's 70s design. You can always go 16v or as we all know it's a great chassis for a swap. lol.
 
I've always loved the idea of an LS swap. Hell my 01 Silverado has a stage 2 cam, headers (which probably wouldn't work) and only 155k on it. The electrical gremlins along with rust kind of makes me want to pull the motor and sell the rest of the truck to put it in the old 740. Sticking with the stock motor would allow me to just address issues as the popup, rather than having to collect all the parts and then have a bigger, more expensive project at once. I have assploded one or two redblocks and one whiteblock so far, which all got replaced with freshened up motors. I haven't taken the dive yet of replacing conrods and pushing these motors which i would like to do. The simplicity of working on these 8v motors is what's always been appealing to me
 
EivlEvo said:
Once you get into head work you have to ask yourself if you really love the tractor motor, because for the money you'll put into the head, I think there are better motors for even less effort. The hell do I know though. Of my 6, 4 are up on stands rn.
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I think the opposite, if you're willing to put in the work yourself making a nice head it is just time and a little investment on some tools.
 
Agreed, I did all my headwork myself, it was fun.

I used a T3/T04E 50 with external wastegate, 3" Tb and MAF, the HO ford injectors, think they were #46 @ 3 bar, full 3" exhaust, etc, no chips or tune. It could do a burnout at 80 mph, but would shoot a lot of flames while shifting. Blew the 3" cat out pretty fast, had to do without that.

Tools were carbide burrs, bead blast cabinet, home made sanding disks. Gasket matching is super important, and you can cut the valve guides down a bit also.

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The trick is to not go too deep and do the exact same thing on each runner. Position the head on a table in the same orientation as it would sit in the car, place new gaskets on the intake and exhaust. Trace inside them with a marker, and there is your gasket matching guide. Under the valve head there is a protruding shroud cast in, remove that. Do not hit the valve seat or you'll be replacing that. More likely a machine shop will be doing that. I removed the valve guides to be able to get all the way in there. Intake runners should not be polished, they need a bit of texture to keep fuel atomized. Bead blasting is my preferred way to get a decent finish. Glass bead, not sand of course.

I'm sure others here have some good tips on hand porting as well.
 
2turbotoys said:
The trick is to not go too deep and do the exact same thing on each runner. Position the head on a table in the same orientation as it would sit in the car, place new gaskets on the intake and exhaust. Trace inside them with a marker, and there is your gasket matching guide. Under the valve head there is a protruding shroud cast in, remove that. Do not hit the valve seat or you'll be replacing that. More likely a machine shop will be doing that. I removed the valve guides to be able to get all the way in there. Intake runners should not be polished, they need a bit of texture to keep fuel atomized. Bead blasting is my preferred way to get a decent finish. Glass bead, not sand of course.

I'm sure others here have some good tips on hand porting as well.
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Good stuff there, thank you!
 
You are welcome, hope you find it fun like I did!

Make sure you buy carbide burrs for aluminum, they have a different tooth pattern so they dont get jammed full of scraps. The aluminum ones have teeth like a drill bit, not like a waffle pattern. A round tip is more useful than a flat topped one. Be careful and maybe get a scrap of aluminum to practice on for a couple minutes. The bit will grab, shake and chatter at certain angles, which leads to deep dents and scuffs.

I found it was handy to make my own sanding disks for after the burr work. A Dremel cutoff wheel bit, the type that has a screw in the end, not the quick connect one. Cut a square out of sandpaper or scotchbrite pad, fasten it into the bit, super inexpensive sanding disk.

It's been a long time since I did this stuff, if I remember anything else I'll post it.
 
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