Originally Posted by cory mcleod
Corey,
Keeping in mind every dyno is slightly different, with the current restrictors, the MC motors are not making 115 HP. With no restrictors installed, yes that statement would probably be very close.
Corey,
Keeping in mind every dyno is slightly different, with the current restrictors, the MC motors are not making 115 HP. With no restrictors installed, yes that statement would probably be very close.
The above statement is very true and the SCCA HAS DATA FOR THE 593 ON THE SAME EXACT DYNO
IMO IF A MODERN CAR WITH AN OPTIMALLY TUNED 593 WERE USED BY ANY OF THE TOP 5 DRIVERS THEY WOULD BE UNBEATABLE WITH THE CURRENT RESTRICTOR SIZES.
The last time that a 2 stroke won the runoffs was when Brian Novak won at Monterey and was on the pole by over 2.5 seconds over Clint in a car that i also built with a Suzuki restriced to 30 mm. Brian led every lap and was in cruise mode after 3 laps, of course Clint gave it all but the 2 stroke was simply too much for the 1000cc Suzuki with 30 mm restrictors.
Thanks ... Jay Novak
313-445-4047
On my 54th year as an SCCA member
with a special thanks to every SCCA worker (NONE OF US WOULD RACE WITHOUT THE WORKERS)
600cc Dyno Results
600cc MC Dyno Results
The NEW Yamaha R6 is 117HP at the wheel. Don't know what that translates to at the crank with the tiny restrictor. The stock throttle bodies are 41mm.
I think you accurately described James Weida and his Scorpion Rotax yet he was beatable at Road America.
What I took from the Runoffs this year is that we finally have the parity that was promised 8 years ago. Hopefully that is good for the class.
Do you remember the mechanical problem with Clint's car during the race?
I believe he melted the right rear suspension puck!
Jay,
Didn’t Steve Thompson win at Mid Ohio in 16 with a two stroke? Don’t think Clint was running a 1000 cc engine at Laguna in 14.
You are correct about Steve winning at mid ohio. My bad memory! But your wrong about Clints engine in 2014. Ask him!
Last edited by Jnovak; 10.20.20 at 6:03 PM.
Thanks ... Jay Novak
313-445-4047
On my 54th year as an SCCA member
with a special thanks to every SCCA worker (NONE OF US WOULD RACE WITHOUT THE WORKERS)
Mr , thorp. Look more carefully at the dyno data lables and you will note rhat the restrictors are radiused restrictors and not the sharp edged restrictors currently required by the SCCA rules. I suggest that you get the correct data with the required sharp edged orifices required by the rules! Go ahead and spend your own money like i did, or at the least read the entire plot
Last edited by Jnovak; 10.20.20 at 7:10 PM.
Thanks ... Jay Novak
313-445-4047
On my 54th year as an SCCA member
with a special thanks to every SCCA worker (NONE OF US WOULD RACE WITHOUT THE WORKERS)
Can you please decipher what this means for a newbie trying to learn about the class?
Thanks.
There are Three Rotax 2-Stoke Engines in the F500 class
1) Rotax 494 (Rotary Valve) 2 Stroke Engine - Appox. 105Hp
2) Rotax 493 (Reed Valve) 2-Stroke Engine - Appox. 105Hp
3) Rotax 593 (Reed Valve) 2-Stoke Engine - Pro Bulid Appox. 115Hp - per the lastest post
There is also the Motorcycle Engines
4) 600cc Motorcycle - 4 Stroke Engine - Pro Build Approx. 115Hp - per the lastest post
I did not want any confusion about the Rotax 2-Stroke Engines. The 115Hp only applies to the Rotax 593 Engine.
The First, Third, Fourth, & Fifth Place finihing cars at the Runoffs were powered by 600cc MC Engines.
The Second Place finishing car at the Runoffs was powered by a Rotax 593 Engine.
The Sixth Place finishing car at the Runoffs was powered by a Rotax 494 Engine.
There were no Rotax 493 powered car at the Runoffs.
Rotax 494 & 493 Powered Cars - Minimum Weight - 800lbs
Rotax 593 Powered Cars - Minimum Weight - 850lbs
600cc Motorcycle Powered Cars - Minimum Weight - 900lbs
All of the Rotax 2-Stroke Powered Cars have a CVT/Clutch Drivetrain
All of the 600cc Motorcycle Powered Cars have a Gearbox Drivetrain
Rotax 494 & 493 Powered Cars - No Inlet Restrictor Plates
Rotax 593 Powered Cars - 25mm Inlet Restrictor Plates
600cc Motorcycle Powered Cars - 28mm Inlet Restrictor Plates
F500 is a Restricted Class it is not a Spec Class!
You tell me what you think it takes to learn this class?
Last edited by sathorp; 10.20.20 at 11:59 PM.
Thanks for the engine details.
Last edited by E1pix; 10.21.20 at 7:57 AM.
Ah, things were simpler when everyone ran the same Chaparral 440 engines. *ringdingdingdingyawwwwwwWWWWWWding ding ding*
But then we wouldn't have this thread at all!
In 2018, 2019, & 2020 4-5 Rotax 494 powered cars participated in SCCA Major Events. Also 1 Rotax 494 powered car participated in the SCCA 2018, 2019, & 2020 Runoffs. There are almosts no 500cc powered cars that road race in the F500/500cc class.
True clint had a problem in the race and failed a suspension rubber due to exhaust heat. Brian had the pole over Clint by about 2.5 seconds and gapped Clint by about 2,5 seconds on lap 1.
All i am trying to say is that a 593 powered car was much faster than a 600cc Suzuki with 30mm restrictors.
Thanks ... Jay Novak
313-445-4047
On my 54th year as an SCCA member
with a special thanks to every SCCA worker (NONE OF US WOULD RACE WITHOUT THE WORKERS)
Mc f500
I've used 2 different engine builders for my 06/07 Suzuki motors. The best dyno sheet either could produce for me (with 30mm restrictors) was 107 hp @ 13700 rpm, with 46 lb-ft torque @ 10250 rpm.
That's hard data.
Remember an "engine build" in this class means fresh (stock) rings and (stock) gaskets to get the compression up to (stock) spec, a (stock) valve grind, and a set of high strength rod bolts.
I think the RunOffs this year demonstrated that a top driver with a 593 and a top driver with a 28mm restricted MC will be very competitive on a long, fast track. I'd gamble the 593 with a well set up CVT would be dominant on a shorter, tighter track.
Personally, I'm not in this to win the RunOffs. The folks in the class are great to hang around with - from the front runners to the back markers. The cars are a BLAST to drive! And I am not braking the bank to run mid-pack in a Major's race (I've been on the podium more than once!) and up front in a Regional (I've won my share in SEDiv).
Find a good car - FV or F5 - and go have fun! Don't feel like your 1st choice is a life-long commitment. If you try F5 for a year or 2 and don't like it, you can always sell it and move over to FV, or vice versa.
George Bugg
-----------------------------
NovaKar
F600
George well said, there really isn't a wrong answer when it comes to picking either class.
I'll reiterate what I've said before; Many moons ago I had a FV and even gave thought to getting another one but I really wanted to go faster. After driving an F500 at an autocross I was sold. The double bonus for me as a regional level guy is I can autocross and road race the car. In my case the road racing is vintage racing.
I was glad to see Wieda run up front at the RunOffs as I showed it is possible with a two stroke car. There was also great racing throughout the field.
When I was at the vintage races earlier this month I got lots of positive feedback on the car, loads of people asking what it was and various technical questions. I'm also hoping that the older cars will start making their way into vintage racing.
I'm still of the opinion if more people drove one of these cars there would be a lot more people running one.
Not enough to see an increase in MPH.
clint knows!
Thanks ... Jay Novak
313-445-4047
On my 54th year as an SCCA member
with a special thanks to every SCCA worker (NONE OF US WOULD RACE WITHOUT THE WORKERS)
Thank you Scott for the dyno chart.
Lets keep in mind radiused Inlet restrictors are not legal in F500 for obvious reasons. In fact you cant even put a chamfer on them per the GCR.
-Eric
The flow difference between a 28mm diameter restrictior with an inlet radius ànd a 28mm restrictor with a sharp edge is about 20 %.
When i did my first MC dyno test the tech guy at the scca told me to use a specific set of sizes with the same radius on all sizes. After i turned in the data one of the SÇCA tech guys called me up and told me to redo the testing with sharp edges and .125" thick plate but by this time i was personally out $4500 to get all the work done so i borrowed the use of a flow bench and then compared the flow bench results between the 2 different types of restrictors and I wrote a report and sent all the bits and data to the SCCA tech people as requested. I made no recommendations for the restrictior sizes at all, I simply supplied the requsted data to the club
I do not know who made the decisions at the club but the club people made the decision to start the 600cc mc powered cars as a regional class only. The MC powered cars were regional for 2 years before the classes were merged into one National class.
There was a lot more involved but the above may give you a tiny idea how much was involved!
If you have any questions just ask and I will do my best to answer your questions.
The above is just a part of my involvement but i cannot imagine how many man hours the club people contributed to the total effort, and I personaly thank them all!
Last edited by Jnovak; 10.22.20 at 2:07 PM.
Thanks ... Jay Novak
313-445-4047
On my 54th year as an SCCA member
with a special thanks to every SCCA worker (NONE OF US WOULD RACE WITHOUT THE WORKERS)
My understanding that when the MC motors were in the gestation stage for F600/F500 competition. Bill Kephart a CRB member at the time and Formula Ford driver since about forever did not want to see the MC motor cars be given their own Formula (extended wheelbase and a number of other 'desirable' features as he felt that such a car would gut FF as the cars would be faster and cheaper..
Until FF adopted their Spec Tire, it was a toss up of who was faster FF or F500. The spec tire has made top level FF slower when compared to the top level F500 drivers.
Inhave always. Thought that f500 and f600 should have been seperat classes with f600 starting life as a regional class. With a simple flat plate 32 mm restrictor. I knew how difficult to optimize the many many variables on the 2 stroke powertrain package is! The CRB DID NOT AGREE! Now no one is happy
I actually do not blame the club for the decision that was made because the poll that the CRB took indicated that the combined class would be very popular. That did not happen, sadly.
I am still of the opinion that seperate class's are the best solution and let the class entries define the status.
Thanks ... Jay Novak
313-445-4047
On my 54th year as an SCCA member
with a special thanks to every SCCA worker (NONE OF US WOULD RACE WITHOUT THE WORKERS)
The big problem at present - many existing 2-stroke cars were bought by individuals who thought putting a MC power train into a existing 2-stroke chassis would be a piece of cake - only to find after they have sliced the car apart that the necessary fabrication skills and abilities far exceed their own. Thus we now have a thousand or so pounds of junk that virtually nobody wants. A functioning race car effectively removed from any potential of being in competition again - either as a 4-stroke or a 2-stroke.
Are there enough cars of each to even split the classes, especially at a national level?
Eric, Thanks for your cordial response.
I didn’t make any claims or statements related to the Dyno Results or the 600cc MC engine. I have no interest in discussing or arguing about 600cc Horsepower numbers, I don’t own one!
These are the Dyno results that where originally posted. The only reason I posted the Dyno Results was to show Unrestricted Horsepower for the 600cc MC Engine. Someone can correct me if I’m wrong but I don’t think there’s any restrictor edge radius effects are involved with the Unrestricted Horsepower shown on the graph.
Again, Thanks for your cordial response it’s appreciated!
Last edited by sathorp; 10.23.20 at 10:08 AM.
?????
My current racing plans for 2021 are to only race at SCCA Regional Events and spend absolutely none of my money at any SCCA Major Event or attend Runoffs that would contribute to the F500 participation rate. I will also not be resubmitted my proposal to the CRB (that I spent 8 months working on last year) which if approved would change the restrictions on the Rotax 494 powered cars to try to improve the participation rate in the F500 class.
George, thanks for your 30 mm dyno info. Does anyone have dyno data on a 600cc mc engine with 28mm restrictors that they can share?
BTW when Brian won the runoffs with the 593 2 stroke with the required 25mm restrictiors and Clint had a 600cc GSXR600 engine with 30mm restrictors. After the race I wrote a letter to the CRB requesting a 31mm restrictior for the next year. I suggest that you look at the video from both of those races. Imo the proper restrictor size for the 600cc motorcycle engines should be 30mm for equal acceleration from 60 mph to 100 mph with the 593 2 stroke engine. I hope that the SCCA instrumented both 2 stroke and 4 stroke cars at the last Runoffs at Road America!
Comments please!
Last edited by Jnovak; 10.23.20 at 2:05 PM.
Thanks ... Jay Novak
313-445-4047
On my 54th year as an SCCA member
with a special thanks to every SCCA worker (NONE OF US WOULD RACE WITHOUT THE WORKERS)
Data?
Blank post
Thanks ... Jay Novak
313-445-4047
On my 54th year as an SCCA member
with a special thanks to every SCCA worker (NONE OF US WOULD RACE WITHOUT THE WORKERS)
Mr Thorp, in the above post item number 4. I am confused please clarify.
Here is a copy paste:
There is also the Motorcycle Engines
4) 600cc Motorcycle - 4 Stroke Engine - Pro Build Approx. 115Hp - per the lastest post
Thanks ... Jay Novak
313-445-4047
On my 54th year as an SCCA member
with a special thanks to every SCCA worker (NONE OF US WOULD RACE WITHOUT THE WORKERS)
If your confused, maybe you should go see a Doctor.
Because, I don’t have the proper Degree or Credentials
to be able to help you.
Away from signal for three days, and will reply to those posting in regards to my posts. Thanks.
So far as the post just above, Geez.
First time checking deep into the ins-and-outs of an SCCA class?
This thread has been absolutely cordial and polite.
welcome aboard
It's clearly written, figure it out!!!
It may be clear to somebody who knows what you mean. However, stating the 115HP only applies to the Rotax 593 is contradictory to you listing the 600cc 4s at 115HP. That could lead to confusion.
1) 494, a rotary valve 2 stroke produces around 105HP peak.
2) 492, a reed valve 2 stroke produces around 105HP peak.
3) 593, a reed valve 2 stroke professionally built produces around 115HP peak per the latest post.
4) 600cc, MC 4 stroke professionally built produces around 115HP peak per the latest post.
Last edited by Daryl DeArman; 10.23.20 at 9:12 PM.
Thanks, for the clarification and rewrite, it's greatly appreciated!
I think at this point in the game the weights need to be evened up then trim the remaining balance of performance with the restrictors. Now that the two stroke is about 1mph faster on top end (same car 2 stroke vs 4 stroke) the weight is a huge advantage under braking and in the turns. 50 pds difference on a four mile track is a huge amount when the MC cars are no longer faster on top end.
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