Hi all. I am getting close to finally turboing the slant but I am wondering about the right choice of turbo for it. The motor will be completly rebuilt with head work like PnP, bigger valves with 3 angle grind, and either keep the 2bbl or switch to a 4. Haven't decided on cam but might go with a GNX grind? The big kicker here is I am considering doing a remote mount setup with the turbo at the back of the car. I am wanting at least 300hp from the setup. I've done alot of reading on compressor maps and I am having a hard time understanding alot of the math and most of the time they ask for info I just don't have like the VE which I don't even know what the stock VE on a stock slant is much less a modded one. At one time I had the idea that a HX30 Holset would be an ideal turbo although now I don't remember exactly why I felt that way. It's a diesel turbo from a Cummins Dodge 5.9. I understand the 5.9 is alot larger than my 3.7 but the RPM limit of both is nearly the same. But I am wondering now if it would be out of the slants RPM range to get much use out of it. I think the slant would spool it... eventually. But would it spool it soon enough to get any real use out of it before the slant redlines. ANYWAY.. anyone here got any good suggestions on what would be a good turbo for my slant that would support 300+hp? Thanks

My turbo is from an '87 Grand National and works very well. There are other guys with slants who have had good luck using this same set up. I know nothing about the technical aspects of this. I know there are guys out on the west coast who do, and will be happy to give you more info later in the day afer they are up and reading the Forum. Josh is one who speaks in in specific technical terms when he discusses this. I am sure he will give you good advice.

Sam

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I too at one point though of using a GN turbo especially since its about as close to a 3.7 as it gets as far as factory turbo engines go. I kinda let the idea go since getting one is not very easy and when you do its pretty expensive even in used non rebuilt condition. I tracked them on ebay for a while and it was outrageous the prices they were goin for. Sam I am interested in your setup though. I'd like to get some ideas on how people are mounting their turbos. If you have any pics of your engine bay and how your turbo is setup I would be very interested to see it/them. BTW I will be turboing a '66 'Cuda for those that may ask the question later. Thanks

Check these two places out for reasonable GN style turbos.

http://www.turbobuick.com/forums/

http://www.gnttype.org/

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11.02 @ 120.56
http://www.youtube.com/watch?v=EAxRmoDgsdY
Chassis dyno
http://www.youtube.com/watch?v=wd6hFGzLJMc

Thanks for the links to the Buick sites. BTW HOLY CRAP thats a fast slant you've got. 11.02? That's insane. Only faster one i've seen is the red valiant with the subaru style top mount intercooler than ran like 10.7 or somethin. He said on youtube that he hadn't done anything to the motor really. I know hes switched turbos from like a t3/t4 to somethin bigger. So Shaker are you also running a GN turbo in yours? Your dyno video says the motor is stock. Does that mean internally stock or completly stock and you just slapped a turbo on it?

Old stock motor ran 11.70's @ 29psi. New motor is running the 11.02 @ 24psi.

I'm still using a GN based turbo. PTE 6262DBB.

That turbo valiant is 300lbs lighter than my car. Our engine builds are very similar.

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11.02 @ 120.56
http://www.youtube.com/watch?v=EAxRmoDgsdY
Chassis dyno
http://www.youtube.com/watch?v=wd6hFGzLJMc

Ok so thats 2 that like the GN style turbos. Whats everyone else using? Anyone got a suggestion for the setup for mine that I mentioned in my first post? Are GN style turbos the best suited for a fairly modded slant? If I did use a GN turbo probably a stock 87 type, would it get me to my 300hp goal and would it spool very fast considering the buick engine is a little bigger but breathes a lot better with a higher rev limit? I worry about using turbos from other engines even of similar size because I am not sure that the slant will flow the kind of air that like say the Buick engine does because again of its low rev limit. This is one of the reasons I considered a diesel turbo. Do I have this all wrong or what? Thanks for the responses everyone

The Buick 3.8 turbo is sized somewhat on the small size so that it's responsive with an automatic transmission. Also, Buick cylinder heads don't really flow all that well which is why there are better ones available. A 225 is only 6 cubic inches smaller than the Buick. At the end of the day a turbo that works well on a mildly warmed up Buick V6 works very well on a mildly warmed up 225.

I have a Holset H1C (in a box) since a friend upgraded his old Dodge. It has a big exhaust housing and no wastegate. An external wastegate will usually perform better, but it adds cost and complexity. I can deal with the cost since the turbo itself only cost me $20. Hopefully the response with the large turbine housing is decent, but if not smaller housings are available. The Holsets are supposed to be very durable and work well at high pressure ratios so if you want a lot of boost from a cheap turbo a Holset might be a good choice. Import guys use these on relatively small engines with small aftermarket turbine housings so I'm curious to experiment with mine using the larger Dodge turbine housings on a larger engine.

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Joshua

Ok so the stock Buick turbo should be perfect for a stock or slightly modded slant then? I had figured that the heads on a stock turbo car especially one thats 21 years newer would have some decent flowing heads. At least flow a lot better than a slant head but my other concern was that the Buick had a higher rpm limit than the slant so my thinking was that the turbo wouldn't reach its full potential since the slant would run out of steam at 3500 to 4k. So say the turbo would spool by 2500, the slant would only run another 1000 rpm maybe 1500 before redline. But I guess its not much of a problem since Sam is running one and is happy with it. Josh what is your take on the remote mount system? My 'Cuda doesn't have a lot of room under the hood even with a slant. Which is one of the reasons I was considering a rear mount kit on top of the stealth factor which is always nice. I was wondering if I did chose the HX30 holset if making it a rear mount would make it lag even more than if it was coming right off the manifold. You did mention the option of a smaller turbine housing which might fix some of that lag. Lastly if I did settle on the Buick turbo Josh do you know if it would support my goal of 300hp which is something like 30lbs/min right? Thanks for the replies everyone.

I know nothing about if the Buick heads can flow, but I've read a lot over at some Grand National forums and they make big big numbers out of the engines. I mean step on big block numbers that are over twice their size .

Anyway, I would fully believe that a GN turbo from the junkyard or used should be capable of 300 hp. The first thing is to look at the engine as a big pump and even forcing air into that pump. If there are restrictions such as flow in the heads or poor camshaft selection a turbo will only enhance so much of the engines capabilities. If that isn't as clear as mud let me try something else.... having a nice car that is quick will greatly benefit from nice tires (maybe even slicks), but you can only do so much if your suspension is worn out. If your engine is bone bone stock and you wish to get 3xx horsepower a turbo is a great tool, but you will have to work with the engine as well.

Finally I'm surprised that a diesel turbo will be brought to your attention if you've read compressor maps. The compressor maps are based on how much exhaust gas your engine puts out. It can be measured or calculated with VE guesses and temperature estimates at a given RPM, than you run the the calculations changing the RPMs to you have something that looks like a linear line(ish). Ideally you will pick a map that makes you have max efficiency for a large amount of RPMs of compromising to mostly max efficiency and avoiding the surge line. For examply I found that making between 350-400hp a GT35r was almost perfect.

So all in all I thing remote mount turbos are a waste of time and money (my opinion which can be thrown out the window to anyone reading). Second I worry that any of the holsets are simply to large dimensionally and in turbine size for a 325hp slant. Maybe you can read about what that fits like Josh had mention, but for this expirement I would go with the GN.

Edit: As mentioned above the "revving" of a turbo has nothing to do with size and rev of one engine to the next, but once again simply how much exhaust gas (which is expanding and therefore pushing) that specific engine is putting out to drive the turbine. So you have smaller turbines to drive smaller outputs, put most of the turbos efficiency is in the middle of the "island". So a narrower island or less efficient turbo probably like an OEM will have greater efficiency at the slants 5000rpm limit than a 3.8l's 6200.
Also, for a remote turbo I believe that a smaller turbo is preferred as the exhaust gasses are cooler down stream and therefore have less "push" on the turbine.

Well I had mentioned in my first post that I can't read compressor maps for whatever reason so being able to or not isn't why I thought of a diesel turbo. I mentioned in earlier posts and call it nieve which it probably is, but I chose a diesel because of they have a simliar redline that the slant does so my idea is that the holset would be built for making power in the same rpm ranges as a slant. Makes sense to me. I am no turbo master or genius and I don't think I pretend to be:) I'd love to be able to read compressor maps but I couldn't figure it out. Now I've seen the DSM guys use HX30s on their 2.0 liters and make 400 plus just from switching from a 14b or a 16g and they said it spools by 3000 to 3500 which is quick considering it's on a 2 liter and came off a 5.9 diesel. I am not saying it's THE turbo to use just saying that it being a diesel turbo doesn't mean it's a bad turbo choice or that it just won't work ya know? Anyway so Runvs also supports the GN turbo. So that's 3, maybe I should start looking at GN turbos again.

Even though our turbos are the same, my car has a very different purpose and performance from Shakers. Right now I am running 8 lbs of boost as compared to Tom's 20 plus. That makes for a very different feeling car. The few times I have pushed mine to over 12 lbs she begins to push you in the back pretty hard. But that will have to wait as there are other concerns, such as lack of Sure Grip rear that need working on first. Even at 8 lbs of boost the rear wheel spins all the way through 1st gear. Tom's car is much, much faster than mine. But mine is still fun to drive, and has potential to tap.

However, to address a couple of your concerns:

1. The GN turbo spools up very easily and with no discernible lag. It is a none issue on my car. With a stock cam it pulls strong right to 5K RPM.

2.You are right, there is not much room under there for the Turbo and associated plumbing, especially if you are going to run an intercooler. I put mine out front behind the bumper, and cut a hole in the bumper to feed it air. The return line is under the fender and ends up being quite tight to the passenger tire, although it does clear.



3. Any turbo the Buick guys are discussing for their cars is likely a good candidate for your slant. You don't have to stick with the OEM unit. Just use their discussions of models, and sizes as a guide for your slant. I know nothing of the technicalities of this, but simply enjoyed the fact that there is a large group of guys out there who do know, and are happy to share their knowledge with you, just as they do on this forum.

4. I am intrigued by the idea of a rear mounted turbo. You got lots of room back there, and the exhaust runs all the way back. And, it is much cooler back there, with lots of air to cool it off. My intercooler piping runs about 10 feet total from the output of the turbo to the TB. Piping from the rear if properly routed and planned might be the same or less. I would like to point out that when you first start this project, it will seem like you have lots of room, and the first components are easy to fit. It is the later ones that get difficult.

5. I put my battery in the trunk. I am happy with that. The air cleaner, which is out of a Cadilac North Star V-8 sits in a well I built where the battery used to sit. I built the well to move the air cleaner box out of the way of the exit pipe from the turbo, and to allow it to pick up air from out side the engine bay.

6. Turbos create a lot of heat. If you put yours under the hood, plan some kind of vents to release the heat. I put vents in the hood, and fenders, plus put the largest fan I could get in between the radiator and engine. It works well now.

There are lots of concerns that will need to be addressed beyond what turbo you are going to use. That is the easiest part of the project really. Good luck. It is feasible, and a fun project if you are patient, and work things out as you go. I had several glitches that it took me quite some time to work out, but things are finally functioning pretty well.

Sam

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Say, I can't be of much help as far as Turbo selection because I run a Big T70 w/ the big shaft and custom exhaust housing. Spools alittle slow to be a good street car but when it hits, hold on. What I can help with is the intercooler pics up front. I have the same front end except grille type. I tucked a 12x24x4" 3" in/out up front. Had to cut the extension behind the bumper and shave some material of the bottom of the bumper to do it but it happened. I did the same on my pops 69 Dart and WOW was that easier. Lots more room up front. So far there is enough ground clearance. Personal opinion on the rear mount turbos, don't do it. Lots of room up front and spend that saved money on something you need. Later
Ryan

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10.74 @ 127.47 mph 1320 ft
6.65 @ 107.80 mph 660 ft

http://www.youtube.com/c/turbo66valiant
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the reason (from what i have read) holsets (HX-35W((wastegated)) and HY-35(non-wastegated) spool faster on gasoline engines, is because gasoline burns hotter and stays hotter than diesel. The HX-35W ( my baby) reachs its full potential of boost at 4000rpms, and wastes at roughly 18lbs of boost stock, you can make your on MBC (manual boost controller) see here

http://www.dsmtuners.com/forums/article ... works.html

also heres a link to a TON of info on holsets
http://www.dsmtuners.com/forums/turbo-s ... stems.html

and heres tons of cool stuff http://www.dsmtuners.com/forums/article ... tercooler/

oh and hows this for innovative ?? http://www.dsmtuners.com/forums/article ... pipes.html super cheap intercooler pipe beader

-Mike

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I am the Guardian, I hate helos, everything leaks.......

Wow guys lots of good info here and even answered some questions I was gonna ask later on. First off, Sam sometime I would really like to see how you routed everything under your hood albeit you've got a lot more room than I do i'd like to see what everyone is coming up with to route everything.

I think I will probably move my battery to the trunk as well and I even had a similar idea about building some sort of airbox that sits in the battery tray. Something like a box with an inlet and an outlet where the turbo inlet pipe would hook to the back with a cone filter inside the box and the inlet part of the box would have a hose going right to the grill. I have a similar type of air intake on my car now except without the box because of the battery still being in it's stock location.

I am starting to feel that maybe the turbo I need is a GN style turbo, maybe use the stock one just to get started then move up but the stock ones have a different flange I understand than the aftermarket ones do and I don't like the idea of having to changes flanges later once I decide to move up from stock.



And yes a lot of the reason for considering a rear mount is the total lack of space I have. On my early 'cuda theres a space between the rad and the grill and I had thought many times about trying to stick the intercooler in there but I found out quickly that theres not near as much room as it looks. I took measurements on about what size intercooler I could fit in there and it would be pretty small, small enough that I wonder if it would just hurt performance rather than help it.

Ryan aren't you the guy on youtube that ran the 10.7 something? Have you changed your intercooler around because it used to be hooked up Subaru style which I liked. I was going to hook mine up just like you had yours cause frankly it's all I had room for. However I also figured i'd have the same problem that the Subarus have with heat soak and I didn't want that. Anyway awesome car i'd like to see low 13s or even high 12s on mine. I'd also like to see how you routed your pipes for the front mount.

Volare those are the same sites where I got my info about how well the Holsets work on the DSM cars. It's pretty insane to throw a diesel turbo on a 4 banger and make 400+ with it where you were making 300+ with regular gas turbos like the 16g Evo turbos and they are pretty cheap in the junkyards. So do you have a HX35 on a car or a truck? If it's a car i'd like to know how well it works on it.

Thanks again guys lots of good info. Next thing I wanna know about is what is everyone doing for fuel mods.