Tim240z Posted August 3, 2001 Share Posted August 3, 2001 Hi All, New login to this site, so hopefully you guys can provide some advise: I am looking to build up a twin turbo 350 sbc to put into my 73 240. The vehicle is completely stripped to bare body now and I have an engine to use as a fitting dummy for now. this is what I want to do: Get a couple of turbos from a 900 SAAB or something similar. I will make up some manifolds and will run a 750 double pumper. This will be mated to a 700R4 which is guaranteed to 600hp. With the 150hp nitrous kit which I have, the combination should be good for 500 to 550 hp at the back wheels. has anyone tackled this before or have any comments one way or another. Also, will the 200 diff from a turbo 280 be able to handle the torque and horsepower? Thanks Tim Quote Link to comment Share on other sites More sharing options...
Guest Fast Frog Posted August 3, 2001 Share Posted August 3, 2001 Good luck Tim!!!!!!!!!!!! I took a look at twin turboing my V8 setup several yrs ago but found that that the 40" X 40" engine bay was too small to accommodate a twin setup without serious cutting up of the wheel wells and fenders. Also, unless someone has just recently developed a TT kit for the sbc, you'd have to do a lot of R&D to develope the intake and exhaust plumbing to make the TT setup work and get it into the engine bay. I'm not trying to discourage you-if something IS out there, whether aftermarket or your own invention, let us know!! Quote Link to comment Share on other sites More sharing options...
Tim240z Posted August 3, 2001 Author Share Posted August 3, 2001 Thanks for the input. My Dad set the South African land speed record with a 'knight rider' generation trans am a few years back (238 mph over a 1KM run) with a 427 twin turbo carburetted engine, so he has some tips for me, but I guess I will have to do all the custom fabricating if nothing is out there already. My main concerns are: Will the chassis and rear end handle 650+ hp? Tim Quote Link to comment Share on other sites More sharing options...
staledale Posted August 4, 2001 Share Posted August 4, 2001 Tim, take a look at this web page. There is a lot of ideas here in all the cars thehttp://www.geocities.com/MotorCity/Downs/8668/index.htmy show. Quote Link to comment Share on other sites More sharing options...
Drax240z Posted August 4, 2001 Share Posted August 4, 2001 Hey Tim, sounds like a sweet project. If you figure you can spare a little extra dough, I'd definately look at getting one of the programmable EFI systems on the market, and going that route instead of carbed. They really aren't that difficult to setup and learn. Can the chassis handle 650+hp? Nope, not stock. At the very minimum I would plan a 12 point cage install and other structural beef ups. (strut tower bars, sub frame connectors, etc) The R200 could likely hold up to that much power if you didn't lauch hard or use sticky tires. I would upgrade for peace of mind, personally. You may want to look at using a R230 out of a later Z, or possibly follow scottie in his quest to use a Corvette IRS rear. Hmm, just re-read your post and realize the 650hp figure was flywheel. At 500rwhp yes, the R200 can survive with a few mods. Sounds like a great project, keep us up to date! Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted August 4, 2001 Share Posted August 4, 2001 Umm, "only" 600hp? 10lbs of boost on a Ford 351W with GOOD heads is suppposed to be good for 650HP or so. I cannot imagine the SBC being much different all things being equal. Also, why twin? Plumbing is easier with no crossover pipe and you can use smaller turbos for fast spool but it gets complicated in a hurry from there in such a small engine bay. You may find some help in the boating world so far as manifolds go or look at some of the junkyard Ford motors that have been put together with flipped over FOX shorty headers. I've actually got twin turbo headers (cast) for a 302 Ford but I've got no idea if they would fit in a Datsun (hrm!). You sure you want to use a carb too? EFI would make life easier tuning wise IMO. Higher dollar but if you're doing 2 turbos you're going to be in deep anyway. An SDS migh tbe good enough and is budget minded. Also, there's a good book out there on turbos - name escapes me - but in the section talking about SBCs there are some interesting quotes... Turbo V8s make big torque it seems (mine sure did!). The book mentions th efirst dyno pull of a turbo SBC. They used Pink rods, steel crank yadda yadda. It hit like 4K RPM and blew apart. Cranked snaped, rods toast - it was a total losss. Seems the torque made was tremendous and the parts simply not up to it! Remember this when you bolt on that 600 horse tranny as the torque will be the killer and the Z is awful light to be taking that kind of torque. Lastly, why? Is this for speed records or a street car? I personally LOVE forced induction and while I've pondered a turbo on the Z it was brief. I think I'm much more likely to end up with an intercooled ATI blower (okay, after the NOS). My reasoning is simple - cost and complexity. This stuff is off the shelf, accessible to me, and known to make more than enough power. It's not as sexy and it's louder, it also won't make the low end torque. I'll live I'm not saying a turbo motor won't work just that perhaps in the power range you can use you might find there are other possible solutions. However if you build it I promise to cheer loudest 'cause it will be one seriously cool ride Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted August 4, 2001 Share Posted August 4, 2001 I think it might be possible to fit them up front. I am considering (way way way down the line) using the same turbo's on a 350. The ones off the Saab's are like falling out of tree's pretty cheaply. Try this link, its Ford based, but its got a great budget twin turbo 351 capri article that will spell out what you need to do, just it'd be on a chevy. He uses a switch to fire an extra injector at 100% when its on boost so the Carb can stay jetted leaner on the primary side. Take a look: web page For a Chevy I think you'd probably want to look at the late model pickups style of header then turn them around, this should dump them right above the steering rack and you could go with some tubing up to the turbo's. At least I think they'd fit in there depending on your accessories. Without a doubt fabrication will be the name of tune, but the results I think would be really worth it. Regards, Lone Quote Link to comment Share on other sites More sharing options...
Owen Posted August 4, 2001 Share Posted August 4, 2001 What kind of intercooler are you going to run, 2 separate ones or a single with two inlets? Check out the Chevy bulletin boards, Z28.com was it? Also I think it was Skulte Designs who had the twin turbo LT1 Firebird. This is one of those subjects we've all thought about and said "one day...". If I ever did it, it would most likely be a big single hybrid turbo. But if the Saab ones are available...try it! Good luck Owen Quote Link to comment Share on other sites More sharing options...
Tim240z Posted August 4, 2001 Author Share Posted August 4, 2001 Thanks for all the input guys. The reason I want to try the TT setup is because it's different. I have built several NA 500+ hp sbc engines, and want to do a forced induction system. I looked at supercharging, but all that stuff is off the shelf bolt on...that's no fun! My only real concern is the strength of the R200. Has anyone out there tried mating up a rear end from a 5 or 7 series BMW? I know that they are plenty strong! I have a good seasoned 4 bolt block from an old truck (early '70s), and will put in a Scat steel crank and good rods and pistons. I also already have a set of HP GM heads and a 750 Holley. The only other problem may be setting up a system that increases fuel pressure as the boost increases, so that the pressure of the air charge doesn't push the fuel back to the tank. The needle and seat will only take 8 or 9 lbs of fuel pressure. As soon as the boost gets to about 6 or 7 lbs, it will begin to lean out the mixture...and that spells problems. Does anyone know of an electrically adjustable fuel pressure regulator? thanks again, Tim Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted August 4, 2001 Share Posted August 4, 2001 Doh, fat finegered and lost my whole reply... Blown cars I've seen with carbs (blow through) have all used a boost refrenced pressure regulator like the EFI cars use only lower pressure. 1:1 is normaly what you want. However every single guy I've talked to that has done this has told me that pressurizing a carb is a nightmare. All sorts of things get weird - for instance floats can collapse under the pressure! All of them have used carbs specially built to handle this application ($$). The last guy I spoke to was using an ATI blower and Demon carb in a pressurized bonnet. This was a super clean Mustang fastback with billet everything! I was interested in how it performed since a blower may be in my future and a carb would be cheaper. He pulled me aside out of earshot of the rest of the people checking out his car and said he hated the carb! It was either lean, or rich, or just not streetable. He was finding himself fiddling with it endlessly to get it to run. If it ran goodlow it ran poor up top and vice versa. He was pretty sick of it and about to go EFI. Sure looked REALLY nice though! He cautioned me to skip the carb as I caution you. By the time you've got a carb built and bugs worked out an SDS system using a carb intake might have ben easier. If you want to fabricate gen up a carb intake with EFI bungs and rails - that'll be fun It'll also flow as well as a carb... Quote Link to comment Share on other sites More sharing options...
Drax240z Posted August 4, 2001 Share Posted August 4, 2001 The SDS system really isn't that expensive either. Members of this board can get a discount if they go through Mike. The SBC setup would cost you somewhere around $1000, plus injectors, and a TPS. Not a lot more to it really. Its worth considering before you start dumping time and money in to the carb'd setup. Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted August 6, 2001 Share Posted August 6, 2001 This site migh tbe helpful... http://www.grapeaperacing.com/GrapeApeRacing/ If nothing the manifolds would be nice. BTW with 12PSI the guy made over 800HP with no intercooling on a 383 stroker. I think we're going to need a bigger boat! Quote Link to comment Share on other sites More sharing options...
pparaska Posted August 6, 2001 Share Posted August 6, 2001 Ya know that might just fit! I was wondering, if the turbos are sized/used in a optimum part of their compressor map, and it's an efficient turbo design, would there be such a thing as a knee in the curve of boost vs turbo output temp? I mean, if you ran it at "ONLY" 5,6, or 7 psi, with optimal turbos, would the heat added to the intake charge be low compared to if you went to 9+ psi? Just wondering about the need for intercooling at lower boost. Just dreaming. Quote Link to comment Share on other sites More sharing options...
Ray Posted August 6, 2001 Share Posted August 6, 2001 If you are looking at doing a carb turbo take a look at this group.. http://groups.yahoo.com/group/BLOWTHRU They mostly do ford stuff but the info is the same.... Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted August 6, 2001 Share Posted August 6, 2001 I almost bid on a turbo manifold on Ebay, if they had two I would have. I suspect it was a aftermarket item that joined the two pipes under the engine and the turbo exited out one side or the other. They were a draw through carb type from what I've seen. It was a ramhorn style with a mounting on top for the turbo, a pair of those would be pretty cool, and might fit if they were angle milled. Be pretty easy to modify a pair of ramshorns with some milling and cast welding. Bolt it to one of those long rod octane tolerant motors with about 15 psi of boost, and well maybe a sds and nice custom manifold and throttle valve. .... Sorry, I must have passed out and dreamed or something.... Regards, Lone Quote Link to comment Share on other sites More sharing options...
Andrew Bayley Posted August 6, 2001 Share Posted August 6, 2001 I played around with the twin turbo idea for quite a while. In fact, I went as far as to buy an after market kit with turbo's and manifolds. However, like the Frog said, what the Z's engine compartment has in length... it lacks in width! With every type of manifold I could get my hands on, the turbo's always wound up sitting too high, or wanting to sit right in place of the shock towers. The only real "practical" solution I could possibly think of is placing the two turbo's in front of the motors. There is plenty of room in the engine compartment for this type of setup. The only major complication would be running the exhaust out of the turbos back over the front crossmember. I was seriously considering running my exhaust through the frame at one point. However, my motivation grew thin as I was turned onto the wonderful, cheap, world of N20. I would love to see somebody do a twin turbo Hybrid V8 Z, and it sounds like Tim is just the guy to try it! My biggest suggestion is to run the turbo's in front of the motors. Trying to squeeze them between the shock towers and the motor will most likely be a major P.I.T.A. (if at all possible). Also, invest in a nice weld-in cage. I skimped out and got an 8-point BAR setup and my chassis still has plenty of stress signs from it's structural weakness. Finally, I wouldn't worry too much about breaking the R200's. The half shafts and stub axel's will break long before anything in the actual diff goes. Good luck, and please keep us well informed! -Andy Quote Link to comment Share on other sites More sharing options...
Tim240z Posted August 6, 2001 Author Share Posted August 6, 2001 Thanks for the comments guys. I was beginning to get a little concerned about this project and was contemplating just slapping together a 500hp N/A V8, but I keep thinking about the turbos.....Can't help but think it would be a fun project. Since I have a second 73 240 to buzz around with in the mean time, I will take my time and fab up a TT setup....At this point the HP potential is unimportant, this will end up being a feasibility study. Once I shoehorn everything in, I will worry about HP. I am going to stick with the Carb setup for now. Tim [ August 06, 2001: Message edited by: Tim240Z ] Quote Link to comment Share on other sites More sharing options...
pparaska Posted August 6, 2001 Share Posted August 6, 2001 Tim, sounds like a blast! Please document it! Maybe offer a kit? Two small turbos on a 350 would be awesome. A custom crosmember might help the exhaust routing? Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted August 7, 2001 Share Posted August 7, 2001 Put the turbos ahead of th emotor - I've seen this done on Fordas and it works WELL. A single turbo would be fine IMO and if it could be made to fit and offered as some form of kit I'd buy it Carb is fine but if I were to do it I'd swap on a throttle body. If you run into problem there's no reason why you couldn't do this as well. OEM EFI intakes aren't too great for higher RPM and are generally built for torque - a carb intake is what you'll want anyway. I'm presently watching two Cutler TBs on E-Bay right now but they're a Dominator flange. Hard to adapt to a 4150 flange? Should I just consider a Dominator intake? What's Cutler's (now Holly?) home page? I've had no luck finding it so far. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted August 7, 2001 Share Posted August 7, 2001 Try this one dude: http://www.holley.com/HiOctn/ProdLine/Products/C950/C950MPFI/MPFIS.html Regards, Lone Quote Link to comment Share on other sites More sharing options...
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