Racing rules make it hard to keep up, How do I cheat legally Options

[Joe Ricard]

Ok now that I got you to open the thread.
as you all know I moved from SM-2 to X Prepared this year in SCCA SoloII.

Street Mod was nearly any engine any size as long as it was Porsche.

Prepared has a displacement rule of not over 1.4mm Bore increase. Guess that leaves the 96mm pistons back on the shelf.

So how do I get more power ot of the racer. I am getting lighter with better wheels and stickier tires etc.

Prepared has no limit on Compression ratio, valve size, ingition, induction, exhaust, piston must be metal and that's about it.

Engine I was building was going to have 71 stroke 96mm chinese pistons in german cylinders hastings rings, 11lb flywheel, 6 puck solid clutch, 86b 86b +5 cam, 44 IDF's 2.0L ported heads with dual valve springs, Tangerine header.

So I guess what I need if it exists is a 1.4mm bigger piston with hiddeous compression.

[groot]

Good luck with that piston.... Jake looked for some for my EP motor, custom jobs with huge expense. We settled on 95mm pistons, leaving that .4mm on the table.

[Joe Ricard]

Cool, so I'm not the only one to read the rule book and try for every little bit.

95's ????? (IMG:http://www.914world.com/bbs2/html/emoticons/idea.gif) Ya got an extra set of them just laying around????????? (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

[DNHunt]

Well I can tell you what not to do. Don't change the outside shape cause it gets your crew chief kicked out.

I'd call Jake. Of course, you'll find that HP costs. Silly high compression ratios need the right cam. My engine is 9.8 static but, the cam bleeds a bunch of that off.

What do they say about stroke? Could you go 94 X 78.4 or even 94 X 80? I imagine I'm not the first guy to think of that so I bet there is a line in the rules about that already. I suspect the torque of a stroker would be really nice on the AX course. My engine feels like a stock 2.0 liter from 2000 to 3500 RPM then the cam comes in. It's fun to watch the tach spin past all the numbers. I smile every time I mash it. I had my 2270 out to Bremerton in January and got in 3 practice runs but, it was raining cats and dogs and I couldn't roll onto the throttle gently enough so I was all over the place. Fun though (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

Dave

[URY914]

I have a set of super rare 97mm p/c if you want to try them. (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

[brant]

welcome to racing$$$$

So, I'd:
knife the crank..
big valves.
custom rods.
bump the compression.
custom cam.
port intake and exhaust.
electromotive.
Tons of head work (200hours flow bench was put into the head design I used to have)
drilled titanium retainers with double valve springs.
custom pushrods.
S-clutch package and flywheel.
headers of course

hmmm...
my old motor.
brant

[jhadler]

Hey Joe,

I guess I'm not sure what you mean by "X prepared". Is it a local indexed prepared class? If so, which index are you going to be running under? EP or FP? Each preapred class has VERY specific allowances as to what you can do to the induction side of the motor. And valves sizes are specified most of the time. With the bigger pistons you mention, I'm guessing that you're going to be building a car under FP (2.0L). Basically, for a competitive motor in a prepared category, you need a full-tilt-boogie race motor. And that, costs $$$$.

-Josh2

[grantsfo]

You can pull a whole lot of weight out of the car and still stay fairly legal in some SCCA AX classes. 914 hides weight in lots of places. Have you pulled the rear muffler heat sheild, all the insulation from behind the seats, the lower part of the dash, replace headlight motors with lightweight manual rods, pull the back pad and install lightweight carpet behind the seats, if you have heavy doors cut out the bars, get rid of the front trunk springs, get rid of engine lid spring rods, lightweight flywheel, lose the side pocket handles on the doors in favor of a simple RS like pull, Can you get away with using plexiglass?, billet hubs, standard tar removal, etc.

[Aaron Cox]

QUOTE (grantsfo @ Feb 22 2006, 10:45 AM)

.....billet hubs, standard tar removal, etc.

i think the billet hubs wont help ya...

the vented rotor weighs a bunch more... and i think wouls make ya slower due to heavier rotaing mass......


just my take

[Joe Ricard]

QUOTE (grantsfo @ Feb 22 2006, 09:45 AM)

You can pull a whole lot of weight out of the car and still stay fairly legal in some SCCA AX classes. 914 hides weight in lots of places. Have you pulled the rear muffler heat sheild, DONE THAT all the insulation from behind the seats,DONE THAT the lower part of the dash, replace headlight motors with lightweight manual rods, GONNA DO THAT SOON pull the back pad and install lightweight carpet behind the seats,DONE THAT BEHIND SPARCO SEATS if you have heavy doors cut out the bars,GOT FIBERGLASS DOOR SKINS FOR MY 70 DOORS get rid of the front trunk springs,DONE THAT get rid of engine lid spring rods,DONE THAT lightweight flywheel, DONE THAT AND WILL DO MORE lose the side pocket handles on the doors in favor of a simple RS like pull, DONE THAT TOO Can you get away with using plexiglass?,YUP LOOKING FOR LEXAN billet hubs, standard tar removal, DONE THAT etc.

Thanks Grant, seems you and I are on the same track. currently 1895 pounds after the Tangerine header install. wheels and slicks will cut another 38 pounds.
Got a line on front fiberglass hood and rear bumper (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

X Prepared is a National level class as per the 2006 SCCA Solo rules. Pretty much the only class I can play in with a the racer. other than SUMPIN mod. and who want to run against URY914 (IMG:http://www.914world.com/bbs2/html/emoticons/dry.gif)

[Richard Casto]

QUOTE (jhadler @ Feb 22 2006, 12:27 PM)

Hey Joe, I guess I'm not sure what you mean by "X prepared". Is it a local indexed prepared class? If so, which index are you going to be running under? EP or FP? Each preapred class has VERY specific allowances as to what you can do to the induction side of the motor. And valves sizes are specified most of the time. With the bigger pistons you mention, I'm guessing that you're going to be building a car under FP (2.0L). Basically, for a competitive motor in a  prepared category, you need a full-tilt-boogie race motor. And that, costs $$$$. -Josh2

I don't follow SCCA "Prepared" classes or rules much, but "XP" looks to be at the top of the "Prepared" class. I thought that there used to be an"AP" class in the past and maybe "XP" replaced it. The 2006 PAX value for XP is slighter tougher than FP.

XP .868
EP .858
FP .863

[Joe Ricard]

You are correct sir. It looked like the results from Ft Meyers showed a Shelby cobra running XP with times close to the hot national level driver in Super Stock Porsche GT3.

The PAX really sucks BTW.

[Richard Casto]

QUOTE (grantsfo @ Feb 22 2006, 12:45 PM)

You can pull a whole lot of weight out of the car and still stay fairly legal in some SCCA AX classes. 914 hides weight in lots of places. Have you pulled the rear muffler heat sheild, all the insulation from behind the seats, the lower part of the dash, replace headlight motors with lightweight manual rods, pull the back pad and install lightweight carpet behind the seats, if you have heavy doors cut out the bars, get rid of the front trunk springs, get rid of engine lid spring rods, lightweight flywheel, lose the side pocket handles on the doors in favor of a simple RS like pull, Can you get away with using plexiglass?, billet hubs, standard tar removal, etc.

I know we are talking XP here, but I am trying to figure out how much of this can be done as part of SM2 rules. Of the ones you mentioned, I am curious about...

* Removing the back pad behind the seats and replacing with carpet
* Tar removal

So far I can't find a way to do this legally in SM2. Anyone read the rules differently??

[Joe Ricard]

Yea SM-2 had funny rules that are subject to interpretation. the area of the car behind the seats of a street mod car can be gutted to the bare metal. yet must have full carpet (IMG:http://www.914world.com/bbs2/html/emoticons/wacko.gif) WHERE?

Street mod can have a carbon fiber engine lid. But I has to keep the steel trunk lids. (IMG:http://www.914world.com/bbs2/html/emoticons/bootyshake.gif)

Stock as delivered 1970 Porsche 914 tipped the scales WAY less than the new minimum wieght of 2100 pounds for SM-2 mid engine RWD.

[alpha434]

QUOTE (Aaron Cox @ Feb 22 2006, 09:48 AM)

QUOTE (grantsfo @ Feb 22 2006, 10:45 AM) .....billet hubs, standard tar removal, etc. i think the billet hubs wont help ya... the vented rotor weighs a bunch more... and i think wouls make ya slower due to heavier rotaing mass...... just my take

From an engineering standpoint, thats right. Billet won't help as much as reducing weight on the rotor, but the big advantage of biilet caps is the reduction of unsprung weight, and it could be enough to keep the unsprung weight the same when you go up to vented rotors. Unsrung weight is like 10 times as bad as extra weight on the chassis. That's why there's so much cashflow into carbon fiber and ceramic brake rotors now-a-days.

On the other hand, pephaps the heavier rotor affects braking speed, since the extra mass affects the rotors tendency to stop or change directions. It would be nice to have some numbers. Hint hint. Anyone a rocket scientist?
(IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

[Crazyhippy]

QUOTE (alpha434 @ Feb 22 2006, 10:50 AM)

On the other hand, pephaps the heavier rotor affects braking speed, since the extra mass affects the rotors tendency to stop or change directions. It would be nice to have some numbers. Hint hint. Anyone a rocket scientist? (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

That's basic physics... The heavier rotor will take considerably more effort to stop.

rotating wieght is bad, the further from the pivot, the worse it is.

If you dont have the need for vented brakes, they WILL slow you down.

BJH

[Joe Ricard]

I like to keep it simple. by that I mean rotating wieght is rotating wieght Wheel/tire and rotor. if you add a pound on the rotor you got to take a pound off the wheel/tire. However the farther out from the axle you minimize the wieght the better. Lighter tires are faster in going and stopping.

Unsprung wieght is the same deal the closer tot he pivot point on the car the better. a heavier caliper increases unsprung wieght. But again a lighter tire off sets that. If not a one for one wieght trade then does the added braking power provide enough benefit to be faster?

I am certain that the new sticky slicks will have way more grip to stop the car than I can generate with stock brakes and good pads.
My car does stop quite well BTW.

The yahoos on SCCA forums believe there are not engine limitations as they see Prepared being a progression from Street Mod.

Makes for and interesting protest.

[Brando]

Hey Joe... Here's an idea... What do the rules say about forced induction in your class? Maybe supercharge or turbo it, keep the displacement you have. Maybe you'll add a little weight to put you in your previous class as you said before you got bumped out because your car weighed too little. Or does forced induction throw you into yet another class?

[Joe Ricard]

Turbos are for Street mod engines. But not Prepared.

WHich is OK cause the Stripper needs a .......... (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

[tommy914]

QUOTE (Crazyhippy @ Feb 22 2006, 01:18 PM)

If you dont have the need for vented brakes, they WILL slow you down. BJH

hmmm. brakes slow you down. who would have thought? (IMG:http://www.914world.com/bbs2/html/emoticons/wink.gif)