bret what calculator do you use?

 

I use one in a program I have here. Since I've used it to figure out what works and what doesn't.

Bret

 

so are you saying i can run the xfi 218 with the spring i have? also out of the 222-230 and the XFI 218 which one will make more power and less lope? merry christmas to you.

 

The 155lbs should be enough but you are moving around 2 times a much mass with that valvespring so don't expect it to like a lot of RPM.

The lift of the XFI stuff is going to help HP and lower the lope (raise idle vacuum).

I think they will make the same amount of power with the right valvetrain stability. The GM cam is going to be slightly easier to do that with.

Bret

 

bret is that 218-224 really dead at 5800rpm?

 

also what the xfi 218 ivc?

 

70 Abdc

 

Like Bret mentioned, the valve spring weight will become pretty important here and so will the retainer weight. I have seen the retainers that came with the 10308-1 kit and those things are like tying a brick to the top of the spring. Hopefully the retainers that you have are much lighter than these.

Spring pressure is the one thing that most people look at. Open/closed pressures and coil bind are what most consider.

the things that most DO NOT consider is spring weight and retainer weight.

Grab a dbl springs Ti retainer and a steel retainer and compare for yourself. Grab a bee hive retainer and compare them all.

As the spring is compressed, the dead coils become basically retainer weight too. This is not knock on Crane, Isky, Comp, etc, this is a problem with any dbl spring and somethiung you have to consider since high RPM will make all of this stuff important.

Realistically with the RPM you are gonna be turning, you will probably be OK with what you have but once you cross 6000 RPM, ALL of this matters much more and will be increasingly more important every 100 RPM after this.

Some do not trust the bee hives and that is cool. To each their own but I ahve used these on ALOT of set ups with no problems and they last when using .600-.620 lift and turning 6600 RPM with the steel retainera nd up to 6900 RPM with a Ti retainer.

Not saying they will last on EVERYONES cam with this lift since we use lobes that are designed with a fluid motion that will make good power AND allow the right parts to last a long time. The XFI lobes are fine with them. Some use some "square" lobes that will be HARD on springs and cause alot of starnge problems since you MUST use some GORILLA springs with tons of pressure and have the studs, rockers, pushrods, etc flexing and changing the actual lift and timing events of the cam while possibly even overpowering the hydraulic plunger in the lifter.

At this point, the car will NEVER run right and be a tuning nightmare since the cylinders are seeing different cam timing for each cylinder and they are always changing.

Lloyd Elliott
972-617-5671
Eportworks.com

 

bret which cam do you think would work better with the A4 3.42 and 2800 vig?

 

The XFI will make more power and TQ but it's going to be harder to control the valves.

Bret

 

would a rev kit control it?

 

Not the valve. Rev Kits only help the lifter.

Lloyd sums it up well...

"Realistically with the RPM you are gonna be turning, you will probably be OK with what you have but once you cross 6000 RPM, ALL of this matters much more and will be increasingly more important every 100 RPM after this. "

Bret

 

what do you mean about controlling the valves(sorry for the dumb ?'s). also i spoke with comp and they told me the ivc @63 on the xfi 218-224? right or wrong? you told me 70.

 

I can't believe it's 63.... that would mean it has 10° of advance in it. Normal comp stuff comes +4

Controlling the valves meaning, limiting valve toss and valve bounce.

Bret

 

bret can you find out if the ivc is 70 for sure? the #'s comp gave me over the phone are ivo25 ivc63 evo75 evc21. if this is the case i come up with 9.22 dynamic. this i would think is to high?