TOPIC:

steell wrote:

In my experience, no single piece is responsible for major HP gains.

That's something that everyone needs to have engraved in their memory, it's the total package that does it, not a set of pipes/carbs/cams/big bore kit/etc, it's all about the combo and the tune.

yep!;)the 1385 just aint the same without the turbo and the nitrous and the alcohal,its a matched set!

Post edited by: wireman, at: 2006/10/30 11:00

Anytime ive used baffles, I was baffeled. where'd the power go?

Very Interesting post.
I had my Z1a on the Dyno a couple of months ago,its got z1000 pistons and barrels, v and h pipe, k and n filters, dyna s coils and ignition, other than that its standard, it made 71.45 bhp.
Next winter when funds/ time allow I hope to fit a wisco 1075, different cams and carbs, I would like to get it up to around 100 bhp at the rear wheel, is this possible?
Someone was recommending fitting Bandit 1200 carbs, has any one done this? A set of nearly new ones are only about £100 over here so it would make for a much cheaper alternative than flat slides etc?

Final notes on HP/Torque – some fact, some opinion:

Final trip to the dyno today w/the 125 mains installed. Picked up 1HP and put A/F ratio right at 13:1. Final corrected RWHP 94HP@9000 60LB*FT@7500

This combo on a chain drive chassis, with the wind just right, and stars aligned, and the big fella shining down…would probably just reach the holy 100RWHP. Professional head porting and a 3 angle valve job might do the same even through the shaft.

More cam would also give this combo more peak HP but at the expense of low/mid range torque - precisely what I’m trying to avoid.

Torque X RPM = Power. (A correction factor is applied depending on the units. For HP and FT*LB divide by 5250)

Torque is what you FEEL when accelerating. Most people making performance engine mods are trying to generate more torque (weather they know it or not)…and extend that torque as high into the RPMs as possible. The torque curve is a much more useful piece of information than the HP curve.

It is possible to create more HP by generating the same torque at a higher RPM (same Torque X more RPM = More HP) but this is usually not as desirable.

There are only 3 ways to make a “substantial” increase in torque (on an engine in proper tune):
1 Increase displacement
2 Increase compression ratio
3 Increase Volumetric Efficiency - (get more air into the engine)

There are two ways to increase volumetric efficiency:
1 Forced Induction (turbo/super charging)
2 Create a “Tuned” intake and exhaust system

A Tuned intake and exhaust system works on high and low pressure pulses reverberating back and forth in the intake and exhaust passages. It’s a delicate system that relies on “pulse timing”. In a tuned intake, a high pressure pulse will arrive at the back side of the intake valve just as it begins to open, forcing the air and fuel into the cylinder (similar to boost pressure in a Forced Induction system). In a tuned exhaust, a low pressure pulse will arrive at the back side of the exhaust valve just as it begins to open sucking exhaust gases out of the cylinder (known as exhaust scavenging). In a tuned system, air and fuel is moved less by the pumping action of the piston and more by the pressure waves in the intake and exhaust. The design and engineering are far beyond me though there are some good online resources that explain some detail. This one is decent (if a bit wordy) pweb.jps.net/~snowbum/InExTuning.htm

This KZ project has been interesting to me because I’ve tried to increase torque by increasing Volumetric Efficiency through a tuned system only (it’s also why I thought it might be of interest to others). My first attempt (MOD 1) was really a failure. The engine generated basically the same amount of torque (53 up from 51). The peak HP number was up (82 from 73) only because the engine was able to extend that torque a little higher into the RPMs. Like I mentioned before, not the most desirable result. MOD 2 was very successful. Peak torque went from 53 to 60 and this torque curve runs away from the other two from 4500 to redline. This is power you can feel! – created by a substantial increase in volumetric efficiency due to a tuned intake/exhaust system.

It’s worth mentioning: Though I’ve touted the 34mm RS carbs, they do have their drawbacks. They don’t like restrictions (no air boxes, no exhaust baffles). They work best when they’re moving lots of air. On this engine; at 4500 RPM to Redline you can run them WOT and they’ll take care of themselves. Below 4K it’s a different story. Too much throttle under heavy load (in 4th or 5th gear) and the intake velocity will drop too far, no fuel gets drawn from the bowl, and the engine will cut out - Not unlike hitting the kill switch. In the lower RPMs, with these carbs, you have to be in-tune with what the engine wants and doesn’t want.

OK guys, that’s my 2 cents. Thanks for listening and helping!

Torque X RPM = Power. (A correction factor is applied depending on the units. For HP and FT*LB divide by 5250)

It's actually Torque X RPM /5252 = HP
A correction factor is applied based on temp and barometric pressure, this is done to achieve a standard of comparison.
Link to calculating hp

Torque is measured, HP is calculated.

Another way to increase power is to increase combustion efficiency by utilizing such things as squish, turbulence, and spark timing. The more of the fuel charge that is burned and the less that goes out the exhaust, the higher the engine efficiency and the more power it will make.

Post edited by: steell, at: 2006/11/02 09:27

Uh..what are squish and turbulence?

Can you do any spark timing on an electric ignition? I'm thinking no..

pyxen wrote:

Uh..what are squish and turbulence?

Can you do any spark timing on an electric ignition? I'm thinking no..

Short and simple explanation with pic

By ignition timing I am talking about creating a spark map, similar to a fuel map on EFI systems. It requires a programmable ignition controller and a dyno.

pyxen wrote:

Uh..what are squish and turbulence?

Can you do any spark timing on an electric ignition? I'm thinking no..

"Squish and Turbulence" is a reference to grooving the combustion chamber to influence the flow of the fuel-air mix to achieve what's called a "multi-flame" detonation - enhancing the chamber efficiency.

Link removed - Steell's article is the better one...

Post edited by: Pterosaur, at: 2006/11/01 08:26

Great thread, thanks guys

larrycavan wrote:

If you can find one, or get him to make you on....give a Murray pipe a whirl..
Larry C:)

I ran a Murray pipe in the mid 80s on a small bore Z. I agree they made a high quality pipe! You can see the attention to detail by looking inside the collector at how the 4 headpipes are joined. I ran a Dragbike H/M national record 5.97 @116 1/8th, in the heat on a 1045, 63" WB 640# 20 years ago.

Post edited by: modprod, at: 2006/11/01 22:31