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The Suzuki
GSX 1100 Turbo Project The beginning The story starts winter 2003 with a '79 Suzuki GS 750 in parts, that was a gift from a friend. My initial thought was to clean, repaint and assemble it over winter and just have some fun with it. Through some old Performance Bikes Magazines, I'd noticed that some GS's were tricked up with modern suspension parts and brakes. So I bought a shipload of parts off of a '91 FZR 600 and put that monoshock swingarm and wheels in, subsequently binning the only spotless parts that came with the GS: the skinny wire-wheels. The bike, that was supposed to be very nearly complete, turned out to miss some vital parts like carbs, electrics, lots of engine-casing bolts and so on. Also the wiring was in a bad state. I'd just about finished rebuilding the GS 750 motor with a good crank when I decided that at 60 HP it wasn't going to be powerful enough. So I sold the engine to a HUGE dude with a GS hardtail chop (a story in itself) and bought back a set of GSX1100S Katana engine, carbs, wiring and full electrics. After pulling the head and inspection, the cylinders, pistons and rings turned out to be scrap. (nothing to do with seller René) I located a set of cylinders and matched forged Wiseco 1166cc pistons on ebay and put that on. Now, with a set of K&N's, dynojet kit and lots more it had gained serious power. After burning down the local roads through summer 2004 and having a lot of fun, I decided that it needed some changes. It had 120 HP at the wheel and lots of torque, but I was only able to catch some modern 600's and nothing bigger than that. (could be just my limp-wristed driving) This was in my opinion partly due to the wibbly, non-confidence inspiring 37mm forks that came off a GS1000 (the orig. GS750 items were 35mm!) and that were souped up with progressive springs and heavier oil. They simply were unable to match todays performance, say equal to my VFR750's. But mainly I needed MORE POWER.
The plan -Get rideable, useable power -Get good roadholding -Get good brakes -Get more power than any standard bike from the shops, say 200 hp at the wheel -Make it stealthy -Make sure it doesn't blow up every other weekend -Make it affordable -Retain the 'oldskool Suzuki' look with modern touches.
So it was TURBO-time.
Why use a turbo? Good question. Basically, an engine is a huge airpump, driven by controlled combustion. The combustion turns the crank so we get motion. To get lots of power, you need to put in lots of fuel and air. The ideal burn mixture is 14.7 parts of air to 1 part of fuel (A/F ratio). Putting more fuel in doesn't get you more power, only less. Now, getting the fuel in isn't the problem. Getting the air in is. So that's why we port and flow heads, put bigger valves in and big carbs on in order to tempt more air to flow in. Now, forget about all this. What we need is to force-feed the engine, and put as much mixture in as we want, not as much as it wants. Just ram the engine full of mixture! Remember the engine is basically a big airpump, you use the combustion to turn the crank and the burned air goes out. There is still some energy left in the exhaustgas, because it flows quite fast. The rule is that you use about 1/3rd of the mixture-energy going in for motion, 1/3rd is wasted on heat, and the rest is tumbling out of the exhaust... So, the simple reasoning is that you take a turbine-wheel of some kind, let it be driven by the exhaust flow, put the wheel on a shaft with a compressor fitted on the other side. This compressor connects to the intake and voila: You got force-feed for your engine. A turbo is THE way to get more power. You can get up to 30 psi of pressure in race-trim, with race-fuel. For road use on pump fuel rougly 15 psi will be sufficient. Think of the fact that at 15 psi you make your 1100cc engine take twice as much mixture, making it effectively a 2200cc engine with corresponding torque levels!... The fact that it works is proven by the event that in F1 turbos got banned because the 1500cc turbo-engines made over 1000 HP...
Why not use a turbo? Every gain has it's pain, and if you are happy with what you have, and/or have no clue to what you are doing, forget about 'simply' fitting a turbo. A turbo spins at very high revs, like 70.000 - 100.000 rpm. You better lubricate this baby or it will all end in tears soon. A turbo needs to ''fit'' your engine in terms of size and capacity. Also, if you want to get any fuel in, you need a big fuelpump and a regulator to keep the fuel pressure above turbo-boost pressure. If for some reason you go over the ideal 14.7:1 A/F, giving a lean mixture, your pistons will melt in seconds. You will need to lower compression in order for the engine to accept boost, or it will start knocking (pre-detonation) and subsequently you will destroy it. For this you need to compensate by retarding the ignition yourself or getting electronics that regulates it for you. You will need to reinforce your engine/ clutch/ trans/ chain in order to keep it from exploding. It is a complex and expensive operation. You need to realise that putting a turbo on will give you access to powers that might be beyond your control and/or imagination, and life-threatening risks are increasing rapidly. Turbos are addictive, you keep wanting more power and you will find yourself wanting to turbo everything, from your wifes' Mini to your lawn-mower.
Do the last two sentences appeal to you? Read on.
Turbo systems There are roughly two types of turbos, the one type that regulates boost by means of a wastegate, and the other that regulates boost through a series of adjustable vanes. The latter is called a VNT (variable nozzle turbine) and this type is what I use. They have less lag (time-delay between opening the throttle and getting actual power, caused by revving-up of the turbo) and are used in most modern Turbodiesel cars. There are two types of turbo systems. One is called draw- or suck-through, because the (mostly) single carb is on the inlet of the turbo and the mixture is being sucked through, compressed and blown into the motor through a manifold. This is what for example Mr. Turbo used on olskool bikes. For: Simplicity. Against: Uneven mixture spread for the four carbs, condensing of fuel in the turbo causing poor idling. The second is called blow-through, because the turbo ''blows'' air though the carbs and into the engine. This is what a Turbobusa (i.c.w. fuelinjection) and I too use. For: Good managability of fuelflow. Against : Complexity.
The Workout In the same Performance Bikes Magazines I had seen some awesome GSX's that had Mr.Turbo kits on. Even secondhand, these were not in my price category. So, I decided to build a turbo kit myself. I had ridden a couple of Yamaha XJ650 Turbos before, and decided that this "blowthrough carbs'' system was what I wanted for the GSX. I bought a partsbike XJ turbo and so I got most of the external parts, like fuel regulator, fuelpump, boost sensor, knock sensor, electronic ignition etc. The main issue is that I cannot weld myself, so building spaghetti headers and aluminum plenums is a no-no for me. So I came up with the standard 4-1 being linked through the swingarm (á la Honda CB600 Hornet) to the Audi-Garrett VNT turbo fitted between the side panels. The other advantage is that this way the turbo is above oil-sump level so it can be gravity-drained without the need to install a scavenging pump. The plenum is made out of glassfibre/ epoxy/ carbon, but may be replaced later with a stainless one when I get infuriated and want EVEN MORE POWER (it's addictive). I reinforced the engine with heavy-duty studs, upgraded oilpump, backplate clutch with extra steel plate and racing springs, adj. camwheels, a base-spacer to reduce compression, and ofcourse a copper turbo head gasket. In the pics you can see that I went back to stereo shocks because I needed the space to put the turbo in. I also put forks off of an FZR 1000 in RF900 triples, together with the bigger 320mm disks. Because of the shorter FZR forks I lowered the rear end too, what gives it an aggressive dragbike-look.
Work in progress
Ready to do this to your engine? Replacing the studs
Fat new copper head gasket, base spacer and HD studs
on 1166cc barrels
Backplate for clutch reinforcement and stronger shock-absorber springs.
Raw version of the plenum. This plenum worked fine,
but for my peace of mind, I had it remade in strainless steel
Pitot tube in plenum inlet. The opening of the tube
must face the airsteam.
First install, snug fit, tubes and wires going in
all directions
First install 2, note reinforcements on the frame
to cope with the extra oomph. Round thing is the blow-off valve
Stealthy or what? Unfortunately the huge airfilter
will give some of the game away
The result
Turbo GSX just after testrun. Sidepanels are off for
inspection, they will cover the ugly bits.
What were the problems I encountered?
1) The VNT's actuator works on vaccuum, and is controlled by a cars' computer normally. I watched it work on my Ford Mondeo TDCI that has about the same VNT unit, and at idle it pulled the arm in to speed the turbo up. Initially on my bike I connected the actuator to the point between the carbs and the head, expecting the vaccuum to pull in the VNT's arm and so closing the vanes thus speeding the turbo up. This didn't work, and so on my first (adventurous) testride boost came in very late. This problem was solved by fitting a "normal" pressure operated actuator and connect it to the plenum. Now, the vanes are normally closed until it reaches 7 psi and the vanes open to control the boost. 2) During the first testride, the bike badly misbehaved when getting from vaccuum to boost. All of a sudden the fuelling was all over the place, giving a wildly jumping A/F meter and also a wildly jumping bike(!). This was solved by replacing the old and brittle o-rings that were between the T-s that connect to the floatbowls. Apparently they were leaking and the oh-so neccesary dynamic boost compensation never reached the bowls, causing the engine not to be able to create a vaccuum to pull the fuel into the throttle bodies. After replacing the o-rings it was running as sweet as a babies' bottom. 3) Oil light flickering. When you just spent hundreds of euros on a nice, shiny turbo and ditto pistons, you are quite concerned when this happens I can tell you. The solution was simple; the turbo circulates a considerable amount of oil from the sump, lowering the level. When you fill it up to the level you normally do, it will cause the pump to run dry! Solution: Fill it up to the max mark. 4) Rough running at idle. Because the fuel pressure needs to be 3-4 psi higher than the boost pressure, the float-needle valves need to be closing perfectly. On mine they were old and worn. This will cause a too high level in the floatbowls and a too rich fuel mixture. This will cause splutter and backfiring. After replacing these buggers the problems are gone.
What's it like to ride?
After solving the problems, it behaves just as well as the standard carbureted bike. Clean, quiet run, good pickup, LOADS of power from 3,500 rpm onwards. This bike is more powerful and intimidating than ANYTHING I've even ridden. My extensive chassis mods have made it quite well balanced, but it's still very crude compared to todays' bikes.The VNT has the ability to set the point where it starts to boost. I could set the point at just above idle, just so that the vanes don't smother the engine and will let it rev out quickly. It's almost immedeately building boost and it gives you a kick in the pants at 3,500 rpm, running at 7 psi. From that point, it gently increases boost to about 12 psi at 9,500 rpm. This way, you get lots of power when you pull away and accelerate, but not so that you fear the bike will flip over backwards (much). As the revs rise, it's like it says: "So, you want more power? I give you more power!" And it will pull like a demented dentist on acid! Low down, just over tickover and before boost, it seems lazier than the standard 1168cc bike was. That one pulled like a steam locomotive when you opened the throttle from tickover. I think this is because of the lower compression and because the engine has to work hard to "suck" it's air through the turbo that isn't spinning fast enough the moment you open the throttle from idle. This will be solved by putting a priority breather valve on the back of the plenum, so it can draw it's air quickly and without resistance. When time will allow, I'll get it dynoed to see how much power it really makes.
May 2005: I installed a priority-breather valve and a boost-controller, set at 15 psi. This transforms the bike into a wheelying, wheelspinning, warp-speed missile from 3000 rpm onwards. The pull and accereration are undescribable.
Aug 2005: After a lot of ignition problems resulting in a refusal to run above 6000 rpm, I replaced the ignition unit with the standard Suzuki item. Apparently the Yamaha item got damaged at some point. I run it like this now, without the knockensor and boostsensor. I modified the ignition rotor so it retards approx 6 deg. on boost but remains the correct timing at idle.
Sept 2005: The clutch won't hold anymore so I fitted an MTC lockup clutch. This clutchplate has 6 arms that swing out and press on the clutchplates so they won't slip. This allowes you to have a featherlight clutchlever and still no slippage on the boost.
The most attracting aspect of this bike I think is the brutal looks, image and the noise it makes. It's not loud, but sounds threatening in a way. The turbo seems to want to suck the whole world in, and whistles as the revs climb, promising even more acceleration and rising the hairs at the back of your neck. The blow-off valve opens when you shut the throttle, like at a gearshift, and provides a fluttering whistle that has dogs running for their mothers and makes you scream in your helmet. Ooohyes, this is what I wanted!
The stainless plenum with the priority breather (reed)
valve; a one-way valve that lets the engine breathe when the turbo
isn't boosting yet
Bigger oilcooler because of running hot on boost.
Lockup clucht with ''pressing arms''
Spacer to clear the assembly
Slightly wider cases with lockup clutch
Left side with short race-silencer. It runs really quiet because the turbo acts as a silencer too.
Specification: ! 90% of the parts on this bike are good, used parts to keep cost down. If you imagine everything bolting together easily, forget it. Almost every part has been machined on or has otherwise been changed to make it fit.
-Suzuki GS750D frame, tank and panels, Giuliari two-four seat, Wes Cooley replica paint -Yamaha FZR600 wheels and swingarm, headlights, indicators, footrests, and master-cylinders -Yamaha FZR1000 forks, calipers and discs, Suzuki RF900R triples, KONI multi-adjustable shocks -Suzuki GSX1100S Katana engine, carbs, wiring, electrics and clocks. Welded & trued crank. Carbs modified to take boost. GS750 pumpgear. -Wiseco forged 1166cc pistons, block bored to match, compression ratio lowered to 1:7.9, '88 GSXR1100 oilcooler -Garrett VNT 20 turbo off of an Audi A6 V6-2.5 TDI -Falicon clutch backplate and HD springs, camwheels and base-spacer -APE HD studs, Cometic basegaskets and copper head gasket -MTC lockup clutch kit -Marshall 4-1 header and modified V&H Kawasaki ZX7R supersport silencer & linkpipe -Dyna coils with Taylor leads and NGK plugs & caps -Yamaha XJ650 turbo system layout, fuel pump, fuel regulator, electronic ignition*, priority breather valve, boost sensor*, knock sensor* and part of the wiring loom*, turbo oil screen-filter -Zerotec airfilter, blow-off valve and boost gauge, VDO fuel pressure gauge -Suzuki Bandit switchgear modified to fit kat wiring -Arias gold 530 pitch chain, 16t Suzuki GSX-R front sprocket, 45t FZR600 rear -Bridgestone tyres, sizes 120/70-17 front, 160/60-18 rear -Castrol GPS 10W40 oil -Weight with oil and fuel, ready to rock-and-roll: 230 kgs.
* Modified, see text
Special thanks to:
-Greg Herlicska, my US friend for constant support, tech info, patience and getting me started anyway -My neighbour Paul for the welding on the exhaust -My old friend Leon for welding on the frame -José van Houdt for the GS remains -Nico Vermaas for support and constant wondering about my crazy plan -René for the Katana engine and stuff -Robin for interest and support -Frans for building the plenum and turbo-inlet in stainless -Peter Hinten of TPS turbo systems for crucial information, http://members.home.nl/peterhin/ -My mates at www.GSResources.com for everything on the GS range -www.olskoolsuzuki.info for excellent articles on frame stiffening, maintenance, etc. -Superkaos.com for wild ideas and 500hp Hayabusas -Falicon USA for parts and fast service, www.falicon.com -Cometic USA for gaskets and fast service, www.cometic.com -Castrol NL for info on- and delivery of the great GPS oil -Everyone who delivered parts or support that I've forgotten to mention
No thanks to:
The people who told me I did everything wrong but refused to tell me how to do it correctly. You know who you are.
Marco.
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