Hey guys,
I've been searching for awhile and really haven't come across anything regarding the max rev limits of a std 2.4. Most of what I've come across is the LR2.4.
Now my question is, would it be alright to spin the std 2.4 to 8.5k just for track (1/4 mile) use? I plan on keeping it at 7.5k for the streets. Any USEFUL input would be greatly appreciated. Thanks!

-Jesse

 

Depends on the specs of the motor.

 

Just as you would see it in the link with their rods...

http://www.maperformance.com/maperfo...vo-stage2.html

-Jesse

 

I am interested in this MAP 2.4L as well and when I pm'd MAP about it they said it was capable of safely revving to 8K. Now keep in mind my setup I asked about was for an engine that was to be used for frequent Road racing/autox. I had told them I needed an engine that will rev to 8K for frequent track duty. I think max on the 2.4L is somewhere around 8500, but at this point I dont need to be revving that high.

 

8500 for occasional drag racing shouldn't be an issue

 

8000-8200 for peak piston speed, some depends on bearing clearances and oil used. 8500 for drag use like Chris said would be fine. Again depending on how it goes together its fully possible to rev higher but like anything, power level and amount its done directly relate to reliability.

Lighter pistons with the 1.13 compression height (like the 2.3 or LR2.0) in the LR2.4s as well as the improvement in R/s ratio allow for more without piston issues. Compression height less than 1.13 starts to create issues all of its own so going to a shorter height than that is not recommended if you want a motor to go for a ton of miles. I have experimented with 1.024 compression heights and it definitely is better on the bore but not as good on the piston at high rpm.

High piston speed on a lower R/s will start to scuff the cylinder faster and depending on the piston can also cause skirt issues. Wiseco pistons put up with this very well as do Manleys.

Aaron

 

Where does the power drop off? If your not making power past 7K there isnt much reason to abuse your engine that much.

 

4th gear at the drag strip will need it.

 

I hope hed make power above 7k, I was making power to 6.75k with a evo8 turbo 9.8hs with a 2.4l. Setup is everything

 

Thanks for your input guys. I just got off the phone with Nick from MAP, and just as chris said, 8500 would be fine. Reason I ask is because I know I'll need a bit more revs at the track with my power. On a break in tune, @26 psi, it made 498/39x on a mustang dyne only spinning up to 7200, and the power and torque kept climbing. I'm hoping I'll be in the low to mid 600s and 500+ tq for a 9sec pass, and I know if I have to shift into 5th, 9 sec pass wouldn't happen.

@johnbradley - I understand that the 150mm rod will have more side load as opposed to the 156mm rod, as well as the cranks that are needed to run each one.

-Jesse

 

4.111?

 

I was looking into that as well. I may get that done once I upgrade to a triple from my exedy twin HD. What transmission do you have in your car?

 

Johnbradley - can you give me some details on your motor? I tried clicking on the link, but its not working. LR or std? Rev limit?

-Jesse

 

Im looking for the rpms but not for drag racing like you guys. At the track, down the straight Im on the top of 4th gear at about 7400-7500 rpms. Shifting to 5th loses a lot of time as I have to then downshift quickly right away and without upsetting the car. Much easier to keep it in 4th, but I have to let off a bit so I dont over rev it since Im still on the stock valvetrain, with evo 8 5pd.
I think part of my recent engine failure is due to revving it to high pushing the car harder, trying to improve my lap times. At this point Im not looking to rev to the moon, but if I can, more reliably than stock, rev to 8k I can cut down my times a bit.

Now looking for a new engine setup Im just researching all my options to see what will work best for me. a 2.4L in my evo sure sounds tempting, especially if I can rev it out to where I need it to.

 

Its working now, had a small issue with the html. I run a 9:1 compression LR2.4 myself. We have built and run several 150mm rod motors as well.