Traction advice

[huckleberry_hound]

We just switched motors, went from an all steel 406 to an all aluminum 18* motor. Set ride hts and rescaled car, got all our percentages right, now we are spinning and having trouble getting any traction,, car was very good with other motor,, was wondering if the 5th coil could be a concern,, its at 38 inches with 300# spring now,, thats where its always been,, any ideas??

[Dragoon55]

If you went from 23 degree to 18 deg the power jump could be significant. How big is the new power plant? Any idea on HP and torque...

[MasterSbilt_Racer]

The driver may just need to get used to the need to be smooth with the throttle. Been there, done that. We have switched between a 23 degree 406 iron block and an aluminum 18 degree 415 and changed nothing but added weight to the center of the car.

[huckleberry_hound]

Thats exactly what we did too,, after we reset the ride hts, the % looked good so I just put weight on the center bar of car. I just didn't know if the extra power and torque would require a change to the 5 th coil,,driver is very smooth but it may take a couple races to get used to the new feel

[hpmaster]

Was the engine dynoed? Who picked the cam? Do you have an open carb spacer or have you tryed one? Sometimes the mismatch of a cam can make you loose, not saying that is the case just beware that it can really make you curse a chassis when it is a motor makin too much torque too fast.

[Bubstr]

Different horsepower curves can demand different gearing also.

[99pbr]

To answer your question on you 5th arm, on a Masters the farther back you come the more "instantaneous" traction....the farther out you go you will get traction later in the stretch. Not sure what car you are running but a good starting point is 35" with 300lbs spring and usually at 3 compression valve (or whatever you shock man tells you) . Rebound is up to you based on entry; more rebound the tighter car will be on entry.

[Matt49]

Just my opinion but if you and/or driver are having a major issue adjusting to the power I would do something to change the balance of the race car. My first change would be to add 0.5-1 percent rear weight.

Again....just an opinion.

[let-r-eat]

I see references to setup changes/horsepower or hp/weight ratio increases and how they effect handling and I often get puzzled. I just can't see how hp changes the amount of adhesion a tire has with the race track?Could you post an overlay of the two engines dyno graphs? Might possibly shine some light on the subject.

[setup479point2]

If you haven't , take gear out , changing to more hp I always adjust gear . That weight you hung on car , move it back further, if you have to have it on car , just in front of fuel cell. Did you soften front springs ( should have ) , did you raise engine , if not front weight is lower so not as much roll. Everything is balance , you changed your balance ,now you have to get it back.

[Egoracing]

setup, recommended setup for an iron block is up and right in the chassis and an aluminum engine is low and left. An Iron engine has a different mass location and the added weight require you to get it higher in relation to the spring contact points on the chassis than an aluminum engine.

[billetbirdcage]

setup, recommended setup for an iron block is up and right in the chassis and an aluminum engine is low and left. An Iron engine has a different mass location and the added weight require you to get it higher in relation to the spring contact points on the chassis than an aluminum engine.

While for a generalization ego is correct, but this is a big pet peeve of mine:

It's the total weight and the COG of the engine that determines where the engine needs mounted. Meaning an all aluminum 430 may very well have the same COG as an steel aftermarket blocked 360 Spec engine but weights 30# less.

So in that case (to handle the same with either engine) the spec motor needs to be the same hieght as the aluminum engine but maybe 1/2" offset left to right depending on how left % come out.

It still puzzles me to this day that I have yet to find someone else that can tell me the COG of their engines. Yes, I know every single COG's of the people engines that I'm heavily evolved with.

[setup479point2]

Just telling what I did to fix a car when we went from a steel block with aluminum heads to a all aluminum . Car was slower after engine change , softened front springs got it back to where it had been , raised engine got it half second faster. You may be right , just know what worked.

[billetbirdcage]

Just telling what I did to fix a car when we went from a steel block with aluminum heads to a all aluminum . Car was slower after engine change , softened front springs got it back to where it had been , raised engine got it half second faster. You may be right , just know what worked.

I wasn't referring to anything you recommended, I was just pointing out the old steel block engine needs to go here compared to an all aluminum isn't always true.

Now if you have a steel block engine and change nothing but the block to aluminum, then yes you lowered the COG of the engine and it will need to be raised. Which is likely the case in this guys situation being a 406 steel to and aluminum engine.

However you need to know what your comparing: Like I said an alum 430 had the exact same COG and a SAS 360 spec engine we had (with in .100 in hieght) and was only 30% lighter. However a 406 steel engine may be 1" higher COG.

It's more then just the block, crank weight and rods as wells as the rest of it come into play. So you need to figure in other things then just the block. Now granted if you not dealing with a short stroke really light rotating assembly steel block engine, you could probably follow the general rule and be close.

Just pointing out just cause it does have a steel block don't always mean it needs a different mounting location. This has always bugged the (not a nice word)(not a nice word)(not a nice word)(not a nice word) out of me, when I see set rules on engine placement when it's not hard to check it out. Again wasn't commenting on anything but the engine placement to explain some things people don't see or think of.

[setup479point2]

No problem , actually liked your post . One thing I've learned is every driver is different and every car is different. I like hearing all the different ideas on here , been setting up cars since 1982 ? and still learn all the time .

[Matt49]

I think VCoG in general is one of the most overlooked things in car setups. Its pretty dang important and most people don't give it much thought.

[Egoracing]

Billet, Do you look at the car as 3 sections? I had someone YEARS ago, that really taught me a lot and he won a bunch of races, said you have to look at the cars centerline (He was referring to weight and to COG) in 3 separate sections. #1 Engine area, #2 Drivers area, #3 Rear Section. He said to really understand the cars it made it easier to predict what was going to happen by making changes to any of the locations. He proved part of his theory when an asphalt series went to perimeter chassis and he showed me how it was going to change the car, then went out and won the next 3 races without an issue while some top teams struggled with the change.

[lovin dirt]

Sorry to show my ignorance, but how do you determine you COG.
Thanks, Mike

[let-r-eat]

The COG is usually around camshaft height give or take depending on combination. The COG of the engine is the axis in which the engine would spin in balance if it were on a rotisserie. Same with the car or any object for that matter.Center of horizontal balance might be a better visual term.

[7uptruckracer]

There is a way to check it with scales and some blocks or a jack, It can be dangerous. But you take your ride height weights jack the back up super high like 18 or 24 inches I don't remember and notate some changes and plug them in to a formula and that gives it to you I'll look it up later at home or someone else who remembers off the top of their head better then me post it.

[Len72P]

Check out Longacre tech articals. Gives a method to check COG chassis. I have done it along with a second method from the internet and they both came out very close. My BW late model with steel block alum heads came out at 19.25 inchs.

[Len72P]

Here's the other one I used , Rob Robinette's C of G Height Calculator. They both came out close to same , within a 1/2 inch.