High compression w/turbo?

[911pcars]

For those who don't think high compression and turbocharging go together, look at this example from Honda. I think the story appears in the current Pop Mechanix mag. Honda has upped the watersports power race with a 4 cylinder, turbo engine. It's only a 1200 cc engine. I quickly scanned it at the styling salon (basically a barbershop) before my number was called.

It runs 16 psi boost with the 11:1 compression and has the usual go fast internals: twin cams, 4-valves/cylinder, EFI, intercooler and engine management that oversees all facets of engine operation (engine temperature, cylinder head/exhaust gas temp, ambient/charge air temp., boost pressure, waste gate operation, etc., etc., etc.). It puts out 165 hp (remember, 1200 cc, 73 cu in. or a little over 1 liter), but I forget the rpm and torque figures, but they were impressive.

I just wanted to point out that it can be done. A few thousand R&D manhours and a big budget probably helps. However, this isn't new technology as the old F1 turbo cars cranked out 1500 hp on 1.5 liters. But this is on a regular ole boat engine running street gas; albeit a very nice one. I read another article where Honda took their Odessy (sp) V-6 and converted it into an outboard motor. Hmmm, water skiing at 80 mph. Sounds exciting.

Go Rams .... or Patriots
Sherwood Lee
http://members.rennlist.org/911pcars

[dickster]

i recently came across the fastest production car in the world (so they claimed), it was powered by a m/bike engine.

0-60 in around 3 secs!! (basically f1/bike performance)

in fact susuki (?) have just released a new bike at a london show. it uses the hiyabusa (?) engine, 1,300cc (around that fig.), they stuck on a turbo and it puts out 250bhp. the std engine is around 175bhp with out turbo.

richard

[beepbeep]

Yes, this is doable. Most of the time they use knock-sensor and ECU that delays ignition and lowers boost every time pre-detonation occurs. Efficiency goes up if you run on the knock-limit but it's hard to tune engine further without changing pistons/lowering compression.

Stock SAAB runs with 9.7:1 compression and boosts more than 1.0 bar. This also develops high exhaust-gas temperatures which must me dealed with nimonic-valves, cast Ni-Cr-Fe "headers" and very inteligent ECU (Trionic). Trionic also detects knock by measuring ionization-current trough the spark-plug so it doesn't need traditional knock-sensor (which is essentially piezo-mic). They develop 250 hp from 2.3 litre...they are tunable to approx. 360 hp w/ stock pistons...most of the time you just break the tranny if pushing for more.

This is not rocket science. Unfortunately, our aircooled heads are badly designed and cannot support high boost with low compression without knocking. Spark-plugs are offset which often makes mixture in other edge of combustion-chamber detonate if boosting too much. Dual-plugs relieve this somewhat. 4-valve watercoolers are much better in this case (Much better in any case, if you ask me).


Cheers.

[Steve W]

I've got a high compression 16 valve SAAB Turbo running 30 lbs of boost using four additional fuel injectors behind the stock injectors, injecting a mix of 50/50 methanol and distilled water at 8+ lbs of boost. No detonation, but I've sheared the teeth off third gear three times from the absolute torque. I'll never forget the expression on the face of a owner of a new 911 Turbo who was driving behind my slow ass at 55 mph on the freeway years ago. He decided to drive around and pass me up. But when he couldn't, even at 140 mph, I could tell he was pissed as hell. His face was stern, cold, and would not look at me. Oh, yeah, I think I embarrassed him in front of the business associate sitting next to him.

There is a SAAB Turbo which placed second at Pikes Peak and does 0-60 in 2.3 seconds. With a 2 liters, a 9:1 compression ratio, and 3 bar(42.8 lbs) of boost, it's got 750 hp and 518 lbs of torque. http://www.saabnet.com/tsn/press/000704.html