Forum: HoseHeads Sprint Car General Forum (go)
Moderators: dirtonly  /  dmantx  /  hosehead

A common 360 engine would have roughly 14:1.

Direct Injection plays a huge role in the ability to run higher compression without the need to run premium fuel.

What RPM range are most guys running? I would think that would have a huge impact on engine life.

Well, we hardly ever turn either 360 or 410 over 8400. The driver/owner seems to have a rev limiter around 8200, I don't care what gear you put in the car.

DA

We used to turn 8700-8800 in our 358 when we ran them and also our 360 when we moved to them.

What does the ratio represent? (14:1, etc.)

How is it measured?

Also, do the high comressions result in the need for methanol, vs alcohol or some other racing fuel? Or is that unrelated?

Thanks!

14:1 means the volume of the combustion chamber is 14 times larger when the piston is at bottom dead center compared to when it is at top dead center.

Essentially you are squishing 14 units of air into the space of 1 unit of air.

Even though I may not know you, I 
care what most of you think!

Even though I may not know you, I 
care what most of you think!

It's a monkey see monkey do atmosphere.  Champ is right, most guys tuen their engines (360) around 8,200-8,400 rpm's.  Your better funded teams where they don't care will buzz them up to 8,800-9,000.  Their theory is that running a deeper gear will pull them off the coener better.  The thing is on the dyno the majority of the engines quit making power around 7,800 rpm's.

Yes highspeed the higher rpm's do shorten the engine life dramatically!!  Used to be when they turned 7,800 max you could usually just do a minimum hone, zyglo the pistons and if they checked out ok which they usually did you could re-use them over.  With the rpm's they turn now the pistons are wore out and you have to put new pistons in every rebuild ($1,100-$1,200).

All the engine builders met with the WoO officials during the Nationals about 5-6 years ago to discuss various topics and ideas.  One engine builder suggested and RPM rule to which he was laughed at.  There were some engine builders that were like "this is the WoO and it should be run whatcha brung and hope you brought enough."  Now that a few years have passed I agree with the engine builder that wanted an RPM rule as I feel it would save teams some money.  Just the way it is now.

And that 12.5-1 is with today’s crappy gas but the computer compensates.

Methanol is a form of alcohol.  I can't speak to the advantages of one form of fuel vs. another when it comes to compression, but I do know that methanol allows an engine to operate at a cooler internal temperature.

Signature here.

It's also been in large part the advent of gasoline direct injection.

The direct injection is a major reason the compression can be bumped up so high in recent years. Seeing all the things coming out in modern vehicles makes it that much more obvious how far behind our local racing engines are. P.S. Im not trying to sound like minthess lol

You can use much higher compression with methanol than with gasoline. 

With gas, higher compression calls for higher octane

Am I correct in suspecting that lots of the old school mechanics don't want to learn about all the electronic stuff? I know I don't (not that I'm anything but a half ass wannabe mechanic)

Used to work on my Econoline, nowadays try to change air cleaner on my Focus... used to be one wingnut & replace paper element, now its some gizmo with warning to let the pros do it. Same with fuel filter: old days, 2 screws, replace the little "can". Now its hidden in the tank somewhere

I'm a curmudgeon....

If I am correct the higher compression also requires a larger camshaft. It's not just one thing. Once you start cranking one thing up the others  have to go up as well. I'd like to know the compression of a midget engine. I wasn't told a few years ago by a car owner he didn't run his engines more than six nights period. 

Blake

I've said for years that a gear rule would dramatically help to reduce costs and help the underfunded teams compete.  I've heard all the arguments.  Yes I know that the higher funded teams will still get more horsepower out of their engines at lower RPMs.  But if teams don't have to spend money on freshening their motors every 5-6 races couldn't they buy more high performance parts?  A driver told me that lower RPMs would make the cars boring to drive.  I asked him how fun it would be to only race against 2 or 3 other cars versus a full field to which he didn't answer my question.  I guess I think the outlaws shouldn't turn anymore than 7,000 RPMs max and 360s or below should be around 6,000 RPMs.

My question is how much of a current sprint car engine could be used in another form of racing?  I think the LS engine makes sense but it could potentially bankrupt some teams if their entire engine inventory is obselete with them not being able to get much out of old engines.

The short answer is yes. This past summer at Eldora for the Jokers Wild, Night Before, and Kings Royal (I can't recall exactly which night) the night it was rain delayed, some cars struggled to get the tires to roll on the wet pavement on the push start stetch on the infield.

I usually look to see what car has trouble getting the tires rolling when the push them out just out of curiousities sake. I beleive it was Clyde Knipp who started to slide sideways and actually swiped a few fans. (I don't know all the details exactly) I was 10 or so pits down from where it happened but the top wing smacked a few unsuspecting fans and split one wide open. They halted the show for a few minutes while they took care of everyone. 

It's a scary thought, really. The push trucks are just focused on getting the cars out and started and they push like hell. 

Yeah Im sure that plays a role. Most of it is that we are creatures of habit. If what we have works right now, then why try to change it? No one like change, especially into the unknown. These LS engines such as the 5.3s are easier than the old engines to work on. There are millions of them around in junkyards all over the country, they are cheap to work on and build, and they are 10x as durable as the sbc equivalent. You can take a stock 5.3 and add a cam and carb set up (which most already have. just need the intake) and make 450hp. For a class such as a stock car or B-mod this would be a dirt cheap engine option.