"Horsepower" of GSX 400 ,GS 425, GS 450 etc.

[Gorminrider]

I've been looking for a simple answer to a simple question: Horsepower of these 400 to 450 engines. The interweb pretty much mixes things up but I believe most are sourced from suzuki.org ....

GSX400L=27hp@8000
GSX400E and T?=44@@9700
GS450 =43hp@9000
GS425=40@8500
GS400=36@8500
... was the L engine de-tuned? Are these hp's correct?

[Mekanix]

GS400L is a misprint. Its not 27 HP. Its 27 KW (kilowatt) so its actually 36 hp. Really its closer to 40 but its subject to the dyno run that gave those number and if they are compensated or properly calibrated.

Hard to say but the 400X has 42hp at least. I had it measured on my first GS400l when I first got it and had it dynoed.

The 450 would have more if it could flow more air through the head and have a higher comp ratio. But its pretty close to the 400.

The 400x has 10.5:1 cp
The 450 has 9:1 cp and less valve circumference compared to the 400x not to mention it doesn't have a TSCC



Hope that helps a bit

[Gorminrider]

Thanks, Mekanix! That explains it really well ! and you've given a good clue ("if it (gs450) could flow more air...") as to the effectiveness of "TSCC" and the 4 valves per each on GSX cylinders too!
...That "27hp" pops up quite a bit on the web and is pretty odd when you can "find" that an old Honda 350 = 36 hp @ 10,500rpm...

[Mekanix]

GS450 has 36mm intake valves

That is a circumference of 113.04mm

The GS40X has two 23mm intake valves

That is a circumference of 72.22mm X 2 which is 144.44mm

Small engine but more flow...

Its often misunderstood thinking its the area of a valve that makes the difference. Its actually the circumference that really counts because the area of the valve will always be in the way but the air escapes around it.

[Gorminrider]

aha!...so circumference X "valve lift" gives an "area" for the gasses to pass through?... then of course, the pumping of the piston versus turbulence has likely kept Suzuki engineers awake at night. anyways, I certainly like it. 44hp on this weight of bike with me aboard scoots along really well and suprising smooth. 6 speeds helps a lot to keep revs in a nice range

[C_OUELLET]

what a great thread! Ive always been worried about the hp numbers I've been spotting on the internet.

[Gorminrider]

I think they all stem from one mistake...there's an awful lot of copy and paste that happens on the internet!