BC

Good stuff Andy. They will be IN my car, and I can do some show and tell, but the car is up on all fours, and the engine is in pieces on a stand a work table.

GoRideSno

Brendan,
That's even better!!!
Andy K

Lagavulin

My take: I would've beat him anyway since it was a top-end race!

Marc's take: Yeah, but the YZF would be more reliable!



I'm laughing at BOTH of us since if you get right down to it, we're fighting just like a couple of little kids!

bcdavis

When we discuss hot-rodding the 928, to get more power, we tend to forget that the competition is also interested in hot-rodding their cars, and bikes... A stock 928 won't beat a stock Z06. A stock 928 will not beat a stock R1. So we are not really comparing apples to apples.

When a hot-rodded 928 goes up against a hot-rodded Vette, Hayabusa, etc, the outcome might not be pretty...

Check these out:

http://217.33.73.68/private/toys4boys2.htm
http://www.supervipersystems.com/Upg...stage_iii.html
http://www.madwheels.com/sledgehammer/
http://www.400gt.com/articles/misc/SupraDyno.htm
http://www.kennedysdynotune.com/z06.htm
http://www.mrturbo.com/bikes_zx-11.htm

But still, I think it is cool that someone is focusing their tuning and 928 knowledge into developing
power more in the realm of cars and bikes like these...

It's not for everyone.
Some people want a Porsche for a daily driver, grocery getter, autocrosser, etc...

But if Porsche could suck 1000 horsepower out of the 5 liter engine of the 917 back in 1971, then we ought to be able to get somewhat close to that today. It put out 580hp NA... The turbo doubled the power output... That was with 1971 technology...

BC

Along those lines, it is a very good move to try and harvest (as Davis here, and Lag previously touched on) as much power from your NA engine BEFORE you boost it. That way it will be all that more efficient an engine, and that much more powerful when psi is applied.

BC

BCDavis - a bike at 230mph? Can you even breathe with the vaccum through your helmet? What if you fall off?

bcdavis

Chris928 already posted an article about what happens when you fall off at 200MPH on a bike...

http://www.pureguts.com/sdm.asp?pg=stories&specific=1

Niels Jørgensen

It's simple: Hold your breath and don't fall off!

BC

You can quote me on this: That guys an absolute idiot, and I hope he doesn't have any children who would possibly continue the stupidity into the next generation.

bcdavis

Especially to run that bike a second time...

Not the smartest move...

Hmmmm, head shake, crash...
Let's take the crashed bike, rebuild it a bit, and take it out again!
Ooops! Still unstable! BAM!

Lagavulin

WOW; all of them!!!

In case you missed it above, here it is again:

Whoa! Just as I stated in the past, I am confident that we’ll see the same thing with our 928 engine; we’ve only caught a glimpse of what’s possible through The 26psi Red S4.

Impressive too, but this one is close to falling to a MURF 928 SuperShark. In the meantime, it does feel good to be in the same ballpark as these guys and at least have a chance though.

Does that horsepower increase look familiar?

https://rennlist.com/forums/showthre...=supercharger/

Although we did have a rear wheel horsepower increase of 86%.

It's going to be fun in the coming months to see what happens with our MURF 928's. As Marc has already stated, we have lots of catching up to do with respect to the Twin Turbo Supra guys, etc. It is those guys which we judge our progress by and compare ourselves to, and we fall WAY short of their lofty mark.

We're going to need a little bit of time. We are confident though and have a plan; let's see what happens with that marvelous, God-given 928 engine!

BC

I have my engine apart right now. Its built like a brick S%ithouse, and you can see that the germans were still in thier "build it and they will come" frame of mind. My only concerns would be:

- Okay fine, put forged pistons in to make sure they can stand a bit of detonation - enough so you know its there and fix it quickly.

- Those rods on my 89 are obviously strong. But would still like to see an 87 rod against the 89 rod, as I believe I remember hearing that the 87 rods are somewhat, noticably, beefier. Did you say that Lag or was it Z? Anyone have photos? I can take a pic of the 89 rod if that would help and post it here.

- Better headgasket, which I believe is on the way.


Question Lag - how much power would I lose off of the 316 number with a 9.0 compression ratio? I was trying to follow your math, but I am a financial professional, so if it doesn't have lots of zeros like 300,000, 400,00, then you'll have to feed it to me.

Z

Tim's already making more peak torque, with the fuel delivery issue and the stock size exhaust pipes on the car. I see that the numbers for that Z06 are also the uncorrected numbers. Since they're selling the installation, I'd guess that the corrected numbers were lower, and that's why they put up the uncorrected ones.

Lagavulin

The 'accepted' number is 4% power loss per point of compression. So in your case, your engine will be at 96% of it's original power:

New HP = 316hp x .96 = 303.36 hp

At 9.0:1 cr, you can safely run 21 psi which'll put your combustion chamber temp at 1074.93 degrees absolute.

Since we're at it, let's see the approximate horsepower this combo will produce:

New HP = (NA hp x Pressure Ratio)
New HP = (303.4 x [(14.6psi + 21psi) / 14.6psi] = 739.8 crank hp

This is the very combo I'm thinking about building during the cold winter months here.

The crank and rods will remain stock, and the pistons forged; I am looking for a used S4 engine.

Hmm, maybe I'll drop the compression slightly more so that I can reliably run more boost...

BC

Its tempting to lower the compression by a point or a half point so I can run more boost when the time comes, but I am trepedatious about the lower power during the time I am getting everything together ($$) to get the kit and driving the car NA.

If you find any good deals on 87 rods, let me know, okay?
Thanks,