The Suzuki GSX 1100 Turbo Project

The Suzuki GSX 1100 Turbo Project

Disclaimer: I accept no responsibility in any form for any injuries, accidents, claims or whatever else because of you trying to do this yourself. This site is purely for info.

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, monoshock 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 a GSXR'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 air pump, 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 13 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 air pump, you use the combustion to turn the crank and the burned air goes out. There is still some energy left in the exhaust gas, 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 roughly 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 1500 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 fuel pump and a regulator to keep the fuel pressure above turbo-boost pressure. If for some reason you go over the ideal 13:1 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 wife’s' 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 waste gate, and the other that regulates boost through a series of adjustable vanes. That is called a VNT (variable nozzle turbine) and this type is what I started with. 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 turbo diesel cars. It proved to be too violent at lower revs for a bike, and as it was too small anyway I use a bigger wastegated turbo now.

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 oldskool 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. fuel injection) and I too use. For: Good manageability of fuel flow. Against : Complexity.

The Workout

In the same Performance Bikes Magazines I had seen some awesome GSXs that had Mr.Turbo kits on. Even second hand, 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 "blow through carbs'' system was what I wanted for the GSX. The main issue is that I cannot weld myself, so building spaghetti headers and aluminium plenums is a no-no for me. So I came up with the standard 4-1 being linked through the swing arm (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 stainless, but may be replaced later with an aluminium one because it weighs a lot now. I reinforced the engine with heavy-duty studs, upgraded oil pump + GS750 gears, back plate clutch with extra steel plate and racing springs, adj. cam wheels, a base-spacer to reduce compression, and a copper turbo head gasket that was later replaced by a graphite one as the copper won’t seal oil ways off properly.

Build pictures

Fat new copper head gasket, base spacer,HD cam chain and HD studs on 1166cc barrels

Backplate on the clutchbasket Lockup clutch with ''pressing arms''

The result

2004 2005 2006

2007:

Repainted bike and engine, which has been rebuilt with a new, bigger KKK k04 turbocharger. A modified up pipe was fitted to the plenum because of the new turbo with exit on the right side instead of left.

After an initial problem with boost compensation for the floatbowls, it goes like crazy and produces 210 rwHP and 220Nm

What's it like to ride?

If you have never ridden a turbo bike, the following will be hard to comprehend.

-At 160 HP the bike is very fast, accelerating rapidly at any speed. It will leave a Busa behind on the straights as it has 160Nm of torque at 3500 rpm already!

-At 210 HP the bike is almost out of control. It doesn’t accelerate like you’re used to, you just twist the grip, the bike goes HISSS and the speedo needle travels upward faster than you can blink. All of a sudden you’ve travelled a big distance. The bike will wheelie and wheel spin simultaneously at the slightest throttle openings. Adrenalin pours out of your ears when you finally get enough and stop. Oh, and opening the throttle bluntly in the first three gears will land you in an ambulance.

The most attracting aspect of this bike I think is the brutal but standard-ish 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. The turbo really screams and you hold on for dear life… You can blow ANYTHING away on the straights.

What next?

At BigCC in the UK I found out that turbobikes making over 600 rwHP are quite common(!). Currently I’m having a spare GSX head ported and flowed to gain a bit more power still… See ya in 2008!

2007

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 front wheel, swing arm, footrests, and master-cylinders. CBR 1000 F rear wheel

-Yamaha FZR1000 forks, calipers and discs, Suzuki RF900R triples, KONI multi-adjustable shocks

-Suzuki GSX1100S Katana engine, carbs, wiring, and electrics. GS750 tacho, bicycle speedo, EFE gear indicator. Welded & trued crank. Carbs modified to take boost. GS750 pump gear with GJG high flow oil pump

-Wiseco forged 1166cc pistons, block bored to match, compression ratio lowered to 1:8.2

-GSXR1100H oil cooler, clocks, headlights and clock/lights frame

-KKK k04 turbo, turbo-tech external wastegate with boost controller

-Falicon clutch back plate and HD springs, cam wheels and base-spacer

-APE HD studs, Cometic base gaskets and graphite head gasket

-MTC “snowflake” multi-stage lockup clutch kit with racing springs

-Marshall 4-1 header and modified Devil carbon silencer & home made link pipe

-Dyna coils with Taylor leads and NGK plugs & caps, without resistors in caps

-Yamaha XJ650 turbo system layout, fuel pump, fuel regulator, priority breather valve

-K&N air filter, blow-off valve and VDO boost gauge

-Suzuki Bandit switchgear modified to fit katana wiring

-EK DRZ 530 chain with new offset 17-42 sprockets