CM Solo Vee Engine choices

[MrGas]

SO


I am turning my FST into a Solo Vee. If you can't sell it Race it some where you can afford. SOLO!
SO which is going to work better?
A. 1585 with 10;1 compression , little larger valves and dual webers

B. 1915 with 9.0 compression, stock valve size, and a single carb. Probably a weber or dellorto of any size.

I like the dual carbs and compression for snappy smooth acceleration, and race gas smell! yum!

But I also believe in bigger is better. more torque not as smooth bottom end power. and super un leaded fuel.

Either one will have more punch than my single Bocar 34 carbed motor!

Any one have experience with either?

Any dyno sheets out there? for either?

I have been building High Perf Air cooled cars for 25 years and cant decide which way to go.

Thanks Greg

[no-cones]

I run a 1915 with the single weber, VZ14 cam, ported and polished heads and pump gas with 32 degrees of timing. Just dynoed 120 ft lbs torque and 92hp at the rear wheels. The AF ratio was really lean at the top end of the rev range. The shop suggested that I switch to race fuel and move the timing to some where around 38 degrees. They also suggested bringing some chokes and jets for some more fine tuning.
If there is anything I can help with just let me know.
Richard

[Barry Ott]

Sorry, but I have no clue which is a better choice, but I'm really glad to see another CM car here in Colorado!

Please look me up when you get to an event, I'll be in 196 X, the red and white VanDiemen FF.

Barry Ott

[MrGas]

I run a 1915 with the single weber, VZ14 cam, ported and polished heads and pump gas with 32 degrees of timing. Just dynoed 120 ft lbs torque and 92hp at the rear wheels. The AF ratio was really lean at the top end of the rev range. The shop suggested that I switch to race fuel and move the timing to some where around 38 degrees. They also suggested bringing some chokes and jets for some more fine tuning.
If there is anything I can help with just let me know.
Richard

Thanks for the info. I like the torque numbers. just need little better top end. What size weber 40 ,44, or 48mm weber?

Sorry, but I have no clue which is a better choice, but I'm really glad to see another CM car here in Colorado!

Please look me up when you get to an event, I'll be in 196 X, the red and white VanDiemen FF.

Barry Ott

Thanks Barry, nice to have a direct competition. Is there only a class of 2? Oh well , not he first time ! lol another reason I like the solo idea is racing others with the PAX factors. Maybe ill have another competitive car!! A lot more fun than a Dmod 70 Vw ghia!! Never competitive wrong classing!!!

[no-cones]

The Weber is a 44 IDF. Top end might be determined by cam choice. The VZ has a lot of lift but not the duration of the W110 If you tell me how, I will gladly post the dyno sheet.
Richard

[no-cones]

OK, I will try to attach pic and dyno............wish me luck.
Remember: Even a blind squirrel finds a nut once and a while. ;-)

[mwizard]

I was going to say you have a nice torque and hp curve, and then I noticed they stop at about 5800 rpm. I hope you make it up on the low end.
I don't know much about your set up, but I would guess a lot more power out of the duel carb set up, but at a bit higher rpm, so you might need to adjust gearing for good autocross results.
Mark

[rave motorsports]

Not sure if it makes a difference or not but we will be racing FST in Denver twice next season and already have 4 cars committed. Rest of the series will be close too. Just something to think about.

[Stan Clayton]

I sure like the looks of a Vee with fat tires!

[MrGas]

I sure like the looks of a Vee with fat tires!

ME TOO! I am just wondering , In a short solo run will I be able to get enough heat into The commonly used SOLO VEE 8 and 10 inch wheels and wide Slicks or would it be better to run the FF SOLO 6 inch wide wheel and tire (that I already have) set up and get better tire temps? Or at least the same as my FF competition? All with Auto X compounds.
The few I have talked to said temps are an issue.

Not sure if it makes a difference or not but we will be racing FST in Denver twice next season and already have 4 cars committed. Rest of the series will be close too. Just something to think about.

Rave, nice to hear there will be some Road Racing FST in CO! I will come out to watch and help pit if anyone needs. 25 year VW aircooled Mechanic and specifically VW Transaxle rebuilder. Love my motor sport!!

Anyone headed to Austin? I am leaving Thursday and got a camping spot at the track!!!! SOOO Excited!

[mwizard]

ME TOO! I am just wondering , In a short solo run will I be able to get enough heat into them or would it be better to run the FF SOLO tire set up and get better tire temps? Or at least the same as my FF competition?
The few I have talked to said temps are an issue.



Rave, nice to hear there will be some Road Racing FST in CO! I will come out to watch and help pit if anyone needs. 25 year VW aircooled Mechanic and specifically VW Transaxle rebuilder. Love my motor sport!!

Anyone headed to Austin? I am leaving Thursday and got a camping spot at the track!!!! SOOO Excited!

Yes to AutoX tires, unless you are just in it for the fun
Mark

[rave motorsports]

Just as kind of a "get the bugs out" session we took our FST's to a local solo event. It was a cool day and we never got over 90 degrees on the spec FST tires.

[MrGas]

Yes to AutoX tires, unless you are just in it for the fun
Mark

I clarified my Q. I am in it to ... be competitive.

Just as kind of a "get the bugs out" session we took our FST's to a local solo event. It was a cool day and we never got over 90 degrees on the spec FST tires.

I know the FST compound tires I ran were HARD. Lasted all season, but now those are JUNK. I have to purchase new ones wherever I Race.

[no-cones]

First, Thank you Mr. Wizard for your observations. I totally agree with you about the hp and where it drops off. As I said, the dyno guy suggested race gas and moving the timing up a bit which according to him will not only give me more hp but move it up in the rpm range. I talked to a few people and they suggested that I mix the 110 octane with 93 pump because of the low compression that I must run. Any suggestion on this matter would be appreciated.
You are also correct that twin carbs would be beneficial, but the rules as they are currently written require me to run a single 2 barrel carb. The biggest problem is the distance from the carb to the heads . Approx 16 in on one side and 18 in on the other. I am going to ask the SEB to change that rule.
OK now I will open a can of worms. I see there is discussion on tires. Here is what I tried and what works for me. I have tried several combinations of tire sizes with Hoosier all 25B compound. in an effort to correct understeer. I also tried various sway bars, (even a rear bar that was a disaster), springs, tire pressures etc. But what finally worked for me was switching to Avons 9 x 13 x 20 front and 10 x 13x 20 rear A11 compound. And I really want to try the A15 compound
Thanks again and keep the suggestions coming, Richard

[mwizard]

First, Thank you Mr. Wizard for your observations. I totally agree with you about the hp and where it drops off. As I said, the dyno guy suggested race gas and moving the timing up a bit which according to him will not only give me more hp but move it up in the rpm range. I talked to a few people and they suggested that I mix the 110 octane with 93 pump because of the low compression that I must run. Any suggestion on this matter would be appreciated.
You are also correct that twin carbs would be beneficial, but the rules as they are currently written require me to run a single 2 barrel carb. The biggest problem is the distance from the carb to the heads . Approx 16 in on one side and 18 in on the other. I am going to ask the SEB to change that rule.
OK now I will open a can of worms. I see there is discussion on tires. Here is what I tried and what works for me. I have tried several combinations of tire sizes with Hoosier all 25B compound. in an effort to correct understeer. I also tried various sway bars, (even a rear bar that was a disaster), springs, tire pressures etc. But what finally worked for me was switching to Avons 9 x 13 x 20 front and 10 x 13x 20 rear A11 compound. And I really want to try the A15 compound
Thanks again and keep the suggestions coming, Richard

Richard, I mix 110 leaded race gas w/ 87 regular, because I need some lead for my old FF valves. The local Union 76 station pumps 100 unleaded gas which is a lot cheaper than my mix.
Not sure what the extra octane will do for you with only 10:1 compression.
My car improved in the understeer area by adding more neg camber in the front. As the tire grip degrades I soften the rear bar. A stiffer rear bar will give you oversteer and you should make sure if you install one, it is easily adjustable. We have a Formula Mazda out here who runs 10's front and rear to handle the oversteer, so you are on the right track.
Good luck and enjoy your car.
Mark

[MrGas]

Is there any one that is running the 1600 Dual carbed set up? I am interested in any data you might have or comparison to a 1915 engine car? thanks Greg

[Lynn]

Vern Maxey has run both the past two seasons, although I think the 1600 blew up this year. The 1915 has more power, the 1600 has better throttle response. My engine builder got the giggles when reading the 1600 specs.

[MrGas]

Definitely leaning towards 1915cc
Some reasons:
Single carb fits under body, Duals require modifying fiberglass.
No replacement for Cubic Displacement!
I can use Heads already prepped for FST. would need to be bored for 94mm Cyl.
Can use my New w110 camshaft / would need bigger for 1600
Case just needs bored for 94mm Or I have another case already bored 94mm, need to check size of line bore.
Looking good to make some smooth Torque and HP.