Who has this combo? Or better yet who has this crank? I know MTI Built a one off 448 cid. But who has gone this big?

 

TTT

 

I am pretty sure you will run out of deck height with that combo. The guys from Diamond said that with a stroke of 4.25" and rods of 6.2" there will not be enough compression height left on the pistons. Going with a shorter rod of 6.125" will help some, but you run into other problems like rod ratio. Better option is to use the 4.125" stroke crank, less problems. Plus the difference in CI is not that much; 441 vs 454.

 

"the difference in CI is not that much; 441 vs 454"

Ya, but it doesn't sound as cool!! <img border="0" title="" alt="[Cool]" src="gr_images/icons/cool.gif" /> <img border="0" alt="[driving]" title="" src="graemlins/gr_driving3.gif" />

 

Sure it can be done. If that MTI engine had a 4.125 bore it would have been a 454.

I really don't think the rod ratio won't be much of a problem unless you expect 150,000 miles out of the engine or want to spin the engine to 7500+.

My next MTI engine will be a 461 or better. <img border="0" alt="[burn out]" title="" src="graemlins/gr_burnout.gif" />

 

This motor will be complete by the end of feb. It took forever to order and take delivery of that 4.250 crank! Do you know if the MTI 448 cid motor has had any problems?

Tony ??? Anyone?

 

I don't like that combo, you'd have to run a shorter rod to still have enough compression height.

I think that much stroke is going in the wrong direction. Would make outlandish torque for a streetcar. Also concerned about piston velocity.

That much stroke works much better with a bigger bore. Keep in mind a Chevy big block is like a 4.500 bore and a stroke like that. I think a 4.126 bore and a 4.250 stroke starts to really go counter to the rod : stroke ratio that most engine builders try to achieve.

That being said, if someone has done one let's hear about it, please also note where the motor made peak horsepower and torque.

 

Daily driver no street car yes!

We are hopeing for 540 RWHP through a auto in this 4400lb car.
<img src="http://image1ex.villagephotos.com/pubimage.asp?id_=466060" alt=" - " />

 

"That much stroke works much better with a bigger bore."

What does the stroke care what the bore is? I can see where a good rod/stroke ratio has it's benefits but what does the stroke have to do with the bore size? I agree that a bigger bore unshrouds the valves and allows for bigger valves but this would be true whether the stroke were 3.5 or 4.5.

I like the idea of a large CI street engine. MEGA TQ with a smoother idle! Big deal if the piston velocity and side loading increase a little so long as you're turning low RPMs.

 

The car will shift at 5800-6000 rpms. The builder said it wont like to rev but it will make monster tourque. And tourque is what you need to get a car like this moving!

The heads are 6.0 L with 2.10 intake and i belive 1.60 exhaust valves!

 

Right, keep the RPMs low and enjoy having a VERY streetable and torquey engine. I plan to shift my 461 at 6000 with an X1 cam on a 116 LSA. I think it'll make over 500 RWHP and idle like stock. The huge surplus of lowend power will make streetable gears like 3.23s work very well. Heck, I might even go to 2.73s!

 

ls1290 - We can make a pistons for the 4.250 stroke and the 6.200 rod but, it will get you only a .915 compression height. Which is very small for a street car. We can make piston with .750 compression heights but, it is not something that we do everyday. Just wanted to clear that up, we can make the piston I just would not advise it for street use.

Thanks,
Chris Gelineau
Diamond Pistons
877-552-2112 toll free