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Author Topic:   RPM Question from New Racer
sleadhead44
Dirt Maniac

Total posts: 109
posted August 01, 2004 05:36 PM  
I am new at this (Only 2 Race nights so far), so help me out if you can. My car is at 4300 - 4700 top RPM, and I can run with the pack just fine. What will happen or why would I want to increase my RPM? My motor guy says it's good for 7000 RPM.

I-B-RACIN
Dirt Maniac

Total posts: 132
posted August 01, 2004 06:39 PM  
wont bog it down make it a rocket of the corner. smoother transition getting out and back into the throttle

bobaluuu
Dirt Freak

Total posts: 474
posted August 01, 2004 09:06 PM  
I agree with the previous reply. but if you can run with the pack at those rpms then why spend the money for a 7 grand motor. I think your tachs off maybe or something else
is.

------------------
Light it up, Baby!

racer17j
Dirt Forum Champ
Total posts: 5390
posted August 01, 2004 09:12 PM  
so like i have said before in other posts does your cam make any more power up there or are you just spinning your motor harder to turn high rpm's
if your cam peaks at 4500 than your not doing anything at 7000 that you could be doing at 3500 look at hp and torque curves they drop off
so if your cam does make more power at 6000 then that is where you want to be but really not much over that
find out what your cam is rated for as far as rpm range then adjust your rpm's to get there you will be much faster then...

drive hard or drive home

WesternAuto17
Dirt Forum Champ
Total posts: 569
posted August 02, 2004 11:52 AM  
If your cam is making peak power at 4000 rpm, you have the wrong cam in the car.

merc123
Dirt Full Roller

Total posts: 28
posted August 02, 2004 03:12 PM  
We run 6500-6800 and 7000 if the car spins coming out of the corners.

sleadhead44
Dirt Maniac

Total posts: 109
posted August 02, 2004 04:39 PM  
Maybe this will help, my motor is a 355 that came out of a Modified and I had it rebuilt. It has easy 400 HP. Should make power to 7000 RPM. This thing should be a screamer, but I am running it in a Bomber Car in 1st gear Turbo 350. There is no bog to the car. When I go into the corner I feel that I have tons of power left, and I could pass the whole pack in the middle of turn 3 and 4 Maybe I just have to learn how to drive this thing. LOL
Any more ideas? Do I need a different gear if I can keep up with the pack? Bobaluuu, I thought the same thing, the tach is working fine and its on 8cyl, I checked it 3 times before I left the house and 3 times at the track.

wizzard
Dirt Freak

Total posts: 306
posted August 02, 2004 06:32 PM  
hmm out of a mod in a bomber must one of those grey areas lol

racer17j
Dirt Forum Champ
Total posts: 5390
posted August 02, 2004 09:27 PM  
3/8 banked track, almost round, not much of a straightaway if any. I have the same gear as you, final gear is a 5.77. Roll out is the circumference of the tire right? It is about 88" depending on which tire for stagger reasons, I think, I will check tonight.

d4490
Dirt Maniac

Total posts: 143
posted August 03, 2004 03:41 PM  
Sleadhead44,

I run at Thunderbird (not yet this year) in the street stock class, and I run a 6.20 final gear with 86 tires. I am looking at putting in a 6.30 or higher gear in the car. I would say you need more gear.

racer17j
Dirt Forum Champ
Total posts: 5390
posted August 04, 2004 09:59 PM  
Hey Sleadhead, I run a 406 with 6.12 final gearing.
A 406 likes to use it's torque, a 355 is alot happier when it's screaming.
I would suggest at least a 6.50 final, if that mod motor has a good crank and rods I would gear it up some more than a 6:50.
I know some of them guys are running their 355's with over a 7.00 final.

Just remember lugging that motor is alot harder on it than screaming it.
Just make sure your head rest is in position.....
Good Luck..

sleadhead44
Dirt Maniac

Total posts: 109
posted August 05, 2004 07:14 AM  
Thanks guys! I checked the tires LR is 86.5" and RR is 88" on Radial Tires (per rules. Here are a few more questions...Which do you use to figure roll out?
What exactly happens if I put more gear in it?
I just bought 2 metric parts cars, although I haven't even checked the gears yet, would I be better off to change to a Ford 9", or use the gears out of the parts cars if it will work? Maybe I should keep getting seat time with what I have and change gears over the winter - whatcha think?

Hey Flanndad, what gear are they running at Ionia, I may go there just for fun, I have a friend in the Pro Stocks #52. What Late Model are you working on?

supwitchew
Dirt Maniac

Total posts: 122
posted August 05, 2004 07:20 AM  
I would switch to a 9" if you're allowed. Durability, safety, cost, and ease of working on them are some pretty good reasons I would think.

Ron_V
Dirt Roller

Total posts: 8
posted August 08, 2004 03:43 PM  
quote:
Originally posted by sleadhead44:
Thanks guys! I checked the tires LR is 86.5" and RR is 88" on Radial Tires (per rules. Here are a few more questions...Which do you use to figure roll out?
What exactly happens if I put more gear in it?
I just bought 2 metric parts cars, although I haven't even checked the gears yet, would I be better off to change to a Ford 9", or use the gears out of the parts cars if it will work? Maybe I should keep getting seat time with what I have and change gears over the winter - whatcha think?

Hey Flanndad, what gear are they running at Ionia, I may go there just for fun, I have a friend in the Pro Stocks #52. What Late Model are you working on?


If you can get a ford 9" go with that.Also I watched you lastnight(atleast I think it was you.White 44)you could go into turns 1 and 3 a little harder.Car looks alot better the last few weeks,You are in a very competitive class.Smooth is fast and with the way the track has been if you can run up high you will go somewhere.The main thing is to realize when the car is tight or loose.I will try and make it down to ur pit this week.As of late we have had a very good car and I usually walk around and get a little help to make my car better.


htrdr
Dirt Roller

Total posts: 13
posted August 08, 2004 08:03 PM  
seat time is most important. if the cam is making poer to 7,000 then you should change to more gear . it will get you off the corner better but the real question is what do you need more seat time or to get off the corner better?

sleadhead44
Dirt Maniac

Total posts: 109
posted August 09, 2004 07:33 AM  
Thanks for the replies every one! Ron V, yep, thats me just learning and trying to hang with the pack. I thought I was doing pretty good in the 1st part of the Consi race, but then the brakes felt "wierd" so I was a little cautious in the corners and 2 cars got by. I found the piston had come out of the LR wheel cylender and had brake fluid all over the place. Got it fixed last night, see you on Sat.

Ron_V
Dirt Roller

Total posts: 8
posted August 09, 2004 12:41 PM  
uuuuggghh im taking it as you have drum brakes.Gotta have disc brakes bro.I will come down and see you sat.

Flanndad
Dirt Freak

Total posts: 255
posted August 10, 2004 05:21 AM  
Hey sleadhead44, I ran a 5.68 at Ionia seem to work real well.

Talk to Allan Koviak out there (at Thunderbird) about the 9 inch rear end for the off season.
He also has a jig to weld them up, I think it's $100 to weld if you supply everything.

My car was his brother's and Allen built it.

[This message has been edited by Flanndad (edited August 10, 2004).]

    

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