Guest Anonymous Posted September 4, 2001 Share Posted September 4, 2001 Is it better for a single large turbo or two smaller turbos for a v8/v6? I understand turbo spool up would be a problem for the larger turbo but would the other 3 or 4 clynders exhaust added to the larger turbo make up for the loss? Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted September 9, 2001 Share Posted September 9, 2001 I'm not an expert but one of the fastest NMCA cars(this one happens to be an S-10 truck) runs twin small turbos on a small block and is eating the BB, blown or NOS cars a new ass. Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted September 9, 2001 Share Posted September 9, 2001 The only reason I can think of for two turbos is faster spoolup or total airflow (huge). Some of the big name Mustang racers only run one turbo - they can spool at the line (slowly) but once spooled they kick butt. I've mentioned before that a friend who's building a turbo (V8) Mustang is pushing me to a turbo. IF I do this I'll do a single. The V8 doesn't need the low end torque of a fast spool IMO and the plumbing might be a nightmare. For that matter two turbos might be more costly than a single larger one? I think you'd be happy with either one really Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted September 9, 2001 Share Posted September 9, 2001 Excellent points, Tim. This single-turbo lag "thing" is going to take a while to go away. Regarding a single turbo setup for a V-8Z, I have advocated the GN design but it seems maybe I did not illustrate it well enough, so I will take another shot. The first pic here shows an aftermarket GN header. To envision how it works, the bottom header is the driver side with the front of the engine on the left and the top header is the pass side with the front of the engine on the right. From the drivers side, there is a crossover pipe that connects to the rear of the pass side header and the exhaust flows forward into the turbo mounted at the front of the pass side head. The next pic shows the pass side on my car and you can clearly see the header flow towards the front. You then have several options to route the DP. A JTR Z has lots of room forwardof the engine for the plumbing and the plumbing could actually duplicate mine. Maybe I am simplying things, but that seems like a fairly simple header to make for a good fabricator. Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted September 9, 2001 Share Posted September 9, 2001 Whew, those headers take some pondering to figure out! I think a GN style setup would be the way to go in a Z. A pair of turbos would be a PITA with so little room to the strut towers. Going forward is the way to go. Do you think the crossover should be up front or underneathin back? Would a GN turbo flow enough for a V8? Sure would be an interesting project.... Quote Link to comment Share on other sites More sharing options...
TimZ Posted September 10, 2001 Share Posted September 10, 2001 I'm not convinced that two turbos will necessarily spool any faster than a properly sized single. As has already been noted, even though there is less rotational inertia, there is also half the flow to each. You might be able to get a bit less backpressure with the twin setup, but that will very heavily depend on your selection of turbos. Also, as somebody already noted, if you can't get enough flow from a single, then you would need to go to twins. this, however, is doubful, unless you are targeting more than 1000hp. Probably the biggest reason to go with the twin setup on a V engine in general is packaging and exhaust routing. This is usually easier, since you can keep the plumbing to the turbos short (usually mounted directly on the manifold), and don't have to deal with some sort of crossover tube. Now, on a V8 Z, the packaging argument might lean back towards a single, since there might not be enough clearance to the frame rails to allow a traditionally packaged twin setup. It might actually be easier to package a single, similar to the mounting on the GN engine. [ September 09, 2001: Message edited by: TimZ ] Quote Link to comment Share on other sites More sharing options...
pparaska Posted September 10, 2001 Share Posted September 10, 2001 Scottie, I'm a bit thick skulled about any technology newer than a carb , but you've swayed me So, if one were to turbo a SBC this way (looks VERY likely this would work, I agree), I think making headers for this would be pretty easy for anyone that's made headers before. My next question is: Does anyone know if such a set of headers already exist? This is the SBC we're talking about - EVERYTHING has been done to it many times. There must be a set of tight fitting headers for a single turbo already out there. Heck, the Scarab company used a set of modified Martin turbocharging headers for their Scarab GT cars. (Finally found my 1980 October HOT ROD magazine that features that car last night!) I'm thinking that having an exhaust tube (like at the aft end of the passenger header as shown) of either 3.5" diameter, or better yet, two 3" diameter flanges, this would be killer. The starter is down there, so maybe sway the turbo to the front of the left side of the engine and exhaust it on the left. With an LT1 type of plenum front air door and manifold, a FMIC, this doesn't look too difficult. Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted September 10, 2001 Share Posted September 10, 2001 Seems we have genuine interest here and I am on a very boring 3-hr telecon, so I started doing some digging . I found a link that has pics that come close to how I see it being done. As I looked at these shots, I could imagine the turbo being moved forward of the head and in to provide more clearance on the sides. That turbine is HUGE and since you probably would not be running a ton of boost, the external wastegate is optional and not having it makes the plumbing less complicated. To make the install complete, the compressor would be re-clocked so that the compressor outlet points to about 8-o'clock with a 90* turn forward pass the radiator into the FMIC, out the other side of the FMIC pass the radiator and into the TB. You then need a 3" pipe on the same side of the compressor for the K&N filter. SBC Single-turbo [ September 10, 2001: Message edited by: Scottie-GNZ ] Quote Link to comment Share on other sites More sharing options...
stony Posted September 10, 2001 Share Posted September 10, 2001 they were starting to cure big turbo turbo lag in japan by going with very small exhaust housing and using really big wastegates. I personally watched a 1000hp gtr launch in a street race then took a look at the setup.... dont remember the compressor size but it was a twin and you could stick your first in the intake of each turbo. the exhaust housing could fit in the palm of your hand!!!! it also had twin wastegates with like 2 inch exhaust valves. The guy said full booste reached at 2500 rpm !!!! i was impressed. i was impressed Quote Link to comment Share on other sites More sharing options...
clint78z Posted September 10, 2001 Share Posted September 10, 2001 Good point about the large wastgate trick, yes it is a trend that has started taking place. Start with a big compressor, and use a small A/R ratio to get it spooled up quickly, then use a big wastegate to dump the rest of the extra gas so you don't killed on the topend with excess backpressure. Quote Link to comment Share on other sites More sharing options...
240Z Turbo Posted September 10, 2001 Share Posted September 10, 2001 Wouldn't you know it, I just finished porting my twinturbo header today. Great topic in my opinion! There is also another aspect not to be overlooked. Turbo technology has come along way and better wheels have enabled for more power and faster spoolup. I hope my twin 16G will outspool my old T64 from both the inertia & backpressure argument and the fact that the Mitsubishi stuff is slightly newer technology. BTW, I am a bit confused on how the larger wastegate can increase spool times! Quote Link to comment Share on other sites More sharing options...
TimZ Posted September 10, 2001 Share Posted September 10, 2001 quote: Originally posted by 240Z Turbo: BTW, I am a bit confused on how the larger wastegate can increase spool times! The theory is that you would use a smaller than normal turbine housing for fast spool, and then use the large wastegate to control the boost and keep the exhaust backpressure down. The idea is small turbine, without the backpressure under boost. I'm sure this works better than small turbine/small wastegate, but my gut feel is that for ultimate power, you'd probably still want to go with a larger turbine. It's probably a good compromise, though. Quote Link to comment Share on other sites More sharing options...
Guest super280z Posted September 10, 2001 Share Posted September 10, 2001 i've heard of another method of reducing turbo lag. i think it's called induction turbo setup. you have two turbos, one small one run on the exhaust and the other bigger turbo fed by the smaller one. this sounds totally awesome to me because you'd reduce your iat by a TON... plus your big boy turbo spools up in no time. anyone seen this setup on a car? i've only heard about a guy here in C.C. using it on a cummins diesel. he's running like 7's in the eigth in like a 4500lb truck... Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted September 10, 2001 Share Posted September 10, 2001 Okay Scottie - how did a mocked up turbo system end up so rusty? I cannot help but wonder if the boat world would offer any solutions to this question of manifolds - maybe airplanes? Th eidea of flipping over shorty headers ins't a new one, I think I've mentioned it before and I know the page with the Ford guys doing that has been posted. Guy that spoke to me about doing this thought the front driver's side area would be good. Thinking about that I believe the steering would be in the way as well as oiling and that the passenger side is a better option. Something very close to the GN setup would probably be ideal if there's room for a DP. Scottie, how much room does your DP have? I don't quite recall... (sigh) Wish I'd had th ehigher rez camera when I was last down there. My next trip is coming up but it seems I'll be in upstate Florida this time... I can snap some pics of the twin turbo Ford stuff i've got if anyone thinks it might be interesting. Internal wastegates and it bolts up to a stock H-pipe on the Mustang Hrm, looked a little more closely at that site and... http://www.y-t-g.com/turbomonte.html Like that intake? That's what I'm shooting for - not sure about the turbo though! Couldn't resist this last one! [ September 10, 2001: Message edited by: BLKMGK ] Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted September 11, 2001 Share Posted September 11, 2001 What's wrong with the turbo? So the compressor is as a tad large . I sure hope he has something supporting the weight of that turbo. The other one I posted obviously was not SS. Boy, Jimbo, you not asking for much are you? Luckily, I think I have what you want. My engine could have been slammed up against the firewall like John Scott's neat V-6 was but it was intentionally not so there was room for the DP and being a V-6, the front of the engine is about the same position as a JTR. Having said that, I do not know if there is room to do as I did, but maybe with a little massaging of the pass footwell, it could work. First thing you will notice is that the GN turbo is in the same position as the one you posted but 90* to the one I posted. The DP is 3" SS and is now wrapped, which makes a world of difference for underhood temps. HTH. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted September 11, 2001 Share Posted September 11, 2001 There are some headers for I believe later chevy trucks that look similar to the mustang shorty style of header. Turned around and with a slight tweeking to the collector would probably just about do the trick. As far as the crossover pipe, theres plenty of room to route the pipe in front of the pan on a JTR V8Z. I routed a 2.5" crossover in front of the sump on the SBC oil pan. This IMHO is a good route for street power just because of the stock smooth engine nature, but with a large can of whoopass just waiting to be served up. It could also do it with less revs required. Someday... Fuel injection first, then this, no question. Regards, Lone Quote Link to comment Share on other sites More sharing options...
Guest jens Posted September 11, 2001 Share Posted September 11, 2001 Here is a picture of a twin cossie t3 turbo equipped gn in a opel manta a http://batman.jypoly.fi/~juhtap/linkki70.jpg This should work fine for 500-600 hp Quote Link to comment Share on other sites More sharing options...
stony Posted September 11, 2001 Share Posted September 11, 2001 Super 280z are you thinking of a sequential turbo? lots of cars run them. stock. ive seen a couple guys in japan run a small superchager for bottem end them a turbo that blows thru the supercharger for topend... wasnt that fast though ;> Anyways if the turbo thing takes off like it did in japan anyone thinking about getting into a shop like that this would be the time ;> As i think in teh near future turbos will be the majority. Oh btw the 1000 hp car i was talking about was an rb26 2.6 L in line 6. If you double the CCs shouldnt you be able to double the horsepower;> Quote Link to comment Share on other sites More sharing options...
240Z Turbo Posted September 12, 2001 Share Posted September 12, 2001 TimZ, this theory might explain why some people are shocked you made 400hp@wheels with the smaller o-trim wheel. You are using a monster wastegate that may be helping to flow and reduce backpressure. I wonder if I can find another Racegate for cheap! Quote Link to comment Share on other sites More sharing options...
TimZ Posted September 12, 2001 Share Posted September 12, 2001 That was the plan... Quote Link to comment Share on other sites More sharing options...
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