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Author Topic:   15 inches of vacuum
DeanHensler
Dirt Roller

Total posts: 20
posted October 24, 2005 01:24 PM  
I'm building a car to run in the "Rookie" class at my local track. Here are the rules.
http://monettspeedway.tripod.com/ROOKIERULES.htm

I'm wondering how much horsepower I can expect to get out of a motor that fits those rules. I know its going to be all about how much I want to spend so I'll say it up front. I've budgeted $3000 for the motor.

Just give me a ballpark on what I can expect.

DeanHensler
Dirt Roller

Total posts: 20
posted October 24, 2005 01:27 PM  
Also, what determines engine vacuum? The reason I ask is because my class only allows you to win 10 races, then you have to move up to the Bomber class.

Ideally I would like to build a motor for the Rookie Class that I could do a minor upgrade to, like a cam and be competitive in the bomber class as well.

Panky AMCA 21
Dirt Roller

Total posts: 11
posted October 24, 2005 03:05 PM  
Cam shaft can affect your engine vacuum. Big cams with big overlaps etc will have less manifold vacuum than smaller cams. Some times port work can effect vacuum, if they are to big. Valve timing can effect it too if you retard or advance your cam timing to change your cam range. the 15 vacuum they allow is basically a good reading for a stock motor.
if you can do any mods at all to cyl head- it's good to de bur inlet side but don't polish. Polish exhaust is good. Think of it like this- inlet side you 2 things to worry about, air & fuel. you have to keep & try mix mix these together better before it hits spak plug, a smooth, shiny finish on inlet port the fuel & air can try & seperate at low speeds. keep it a bit rough for turbulance.
Exhaust you only have to get rid og gas only. Smooth & shiny is o.k
Your valves, you can radious the back of valves after you cut the angles. Good job on the seat cut will also help. You wanted to know a ball park HP. The rules said v8 OR v6, which one are you going to use.Basically you have read the rules and it's not about what they say, it's about what they don't say. But I beleive your $ 3000 budget should well and truely cover it.
Hope this help any.

[This message has been edited by Panky AMCA 21 (edited October 24, 2005).]

DeanHensler
Dirt Roller

Total posts: 20
posted October 24, 2005 03:11 PM  
383 stroker.

James Ott
Dirt Maniac

Total posts: 131
posted October 24, 2005 06:37 PM  
What the heck kinda rules are that? what is external parts? ****p Any way you can run a decent cam and still make 15" especially at 1000 rpm I had a 288 dur. and 490 lift and still made 16.5" @ 800 had to pull rules said 17" bummer. Talk to a good local engine builder. And talk to the tech guy. You go doing lots of porting in your heads and it might not be legal. Build a bullet proof bottom end. You have to first finish to finish first.

dirt_mopar99
Dirt Forum Racer

Total posts: 94
posted October 24, 2005 08:56 PM  
Change the engine budget to 2k or less, spend 1 k on handling. You'll be happier!

DeanHensler
Dirt Roller

Total posts: 20
posted October 24, 2005 09:06 PM  
Where can you put $1,000 into handling with these rules?

Panky AMCA 21
Dirt Roller

Total posts: 11
posted October 24, 2005 10:24 PM  
quote:
Originally posted by DeanHensler:
Where can you put $1,000 into handling with these rules?

Must agree there preety **** rules.

dirt_mopar99
Dirt Forum Racer

Total posts: 94
posted October 25, 2005 06:57 PM  
Springs, shocks, offset wheels, decent tires. My point is you shouldn't need a 3k motor in a class like that.

DeanHensler
Dirt Roller

Total posts: 20
posted October 26, 2005 06:45 AM  
To run up front I'm assuming I'll need 350-400 horsepower in the motor.

sc1 racing
Dirt Freak

Total posts: 419
posted October 26, 2005 07:05 AM  
people still dont realize a stock motor with a good driver and a good handling car will do better than a kiler motor and car and half *** driver..

build you a flat top 350, with around a 480 lift cam. you will make plenty of torque and around 300 horses. then concentrat on driving and setting car up.

i have raced a stock car with a stock 305 with humps, and a small cam and finished ahead of the 383/406 guys.

anything you do to a motor effects vacum. more compression the better.

DeanHensler
Dirt Roller

Total posts: 20
posted October 26, 2005 07:09 AM  
Whats the highest compression you can run on 93 octane fuel?

sc1 racing
Dirt Freak

Total posts: 419
posted October 26, 2005 07:15 AM  
sorry i take that back you cant run a cam that isnt stock. go to advance auto parts, or oreily auto and ask for a blue racer cam. it is a stock grind for the 375 hp corvete. no noticable lope, and bye the rules it is legal since it is a stock item.

dont know the exact comp ratio but i ran a set of k/b .250 domes with a 72 cc head on 93 octane and ran like a charm for my buddy. i think he used some of the nitro fuel additive. conservatly at a 10 to 1 comp.

magician227
Dirt Full Roller

Total posts: 55
posted October 26, 2005 09:58 AM  
Ill give you some info on Monett. First, it is tight as heck. The turn are deceptivily tight! I agree, setup there is really important. We ran our Springfield bomber there this year. We pulled everybody down the straights, but got creamed in the turns. We are only getting about 340 HP at the wheels, so you dont need big power to run there, even in the bomber class. As for what to do on the setup, there are guys on here that can help with that much better than I can. I can tell you this, most cars there have the right front laid in a ton. Im guessing they are moving the upper control arm brackets or running 2 left side arms.

Seriously, you might want to check out starting at Springfield in the bombers. The drivers there will help you in so many ways and will not run you over if you are new. I started just last year with a complet car I paid 1000.00 for. I was the last car running in my first 5 races. This year with a lot of help from this site, and even more help from other drivers, I have a best finish of 7th.
I have personally seen racers there take parts off their tow trucks and loan them to other drivers to get them in the show. Not to mention the big-buck sponsored drivers give away oil, filters, and all kind of sponsor goodies to us poor-folks!

Im not knocking Monett, necesarly, but what I saw when I raced there was 3 blown engines, and 4 cars flipping off the corners.

Also, if you havent been to Springfield lately, it is not the old little go-cart/mini-stock track anymore. It is a full 3/8 highbanked oval.

If you are interested, PM me and we can get together. You can check out my car and maybe get some ideas.

Magician

Oh, as for vacuum, I run a 355, flat top hypers, massaged 882 heads, quadrajet carb, scat9000 crank, and a 494/494 Lunati cam. I pull 17in at 1000 RPM. Another nice thing about Springfield, no cam rules. Just run stock exhaust manifolds, iron intake and heads, and no roller anything, and you are good. With the shorter straights, the big cube/big buck engine guys dont really have the big advantage. Driving style is key here. In fact, one of our most experienced drivers brings a bone stock, and I mean BONE STOCK, metric and wins at will just with driving line and throttle control.

DeanHensler
Dirt Roller

Total posts: 20
posted October 27, 2005 04:03 PM  
I'd like to come look at your car, where do you live?

racer17j
Dirt Forum Champ
Total posts: 5390
posted October 29, 2005 09:10 AM  
spend your money on making the car handle.
A big motor does you no good if you can only race down the straights.

Ego Racing
Dirt Forum Champ
Total posts: 724
posted November 10, 2005 06:48 PM  
Buy a GM 602 crate motor pull the roller rockers and put regular type arms on it. 350hp 400ftlbs of torque, all GM parts and will pull 15 inches of vacume. $3200 and run it for 2 seasons or longer before a rebuild!

racer17j
Dirt Forum Champ
Total posts: 5390
posted November 11, 2005 12:15 PM  
S**** the crate idea! up here (Canada) they are double what I just spent to build a balanced 355 flat top stock cam. They are too darn expensive. If your rules say you can run your own stuff why go crate? Does'nt make sense to spend more on less.

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