M2SPEED

Not sure why the more knowledgeable ones here on the forum have not chimed in yet. Possibly it is very new a are not sure about the XFI. My concern is it probably has a very flat nose, and Newton’s first law of motion is going to be one of the concerns.

Gearhead1

It's ground on a 110. What I'm attempting to accomplish is a baby Patrick G torque cam. I don't need or want to rev to 6500+ RPM's. This cam (hopefully) will peak about 6300 rpm's or so with a shift point of 6500. It should be arriving as soon as the middle of next week. I hope I made the right choice. I'll be using the springs that came with my Dart 205's, also. That's why I went with the shorter lift that these lobes offered. Again, I hope my choices don't bite me in the backside.

DAPSUPRSLO

iTrader: (14)

I've used one on a customers z06, the 242 at .050 exhaust lobe to be exact, but we never had a chance to dyno and now he has a charger setup and blower cam in it. It did feel strong to me though and pulled all the way to 6850 with no float judging by my sotp. We did have 921 springs in this setup shimmed up quite a bit for some big pressure in comparison with most 1.29" o.d. springs for hydraulics.

1989GTA

Interesting that you were able to pull to 6850rpm with no valve float. That is good news as Comp list it to 6200rpm. I will be installing the 218XFI in my 3rd gen build up but will not have any info until late summer.

DAPSUPRSLO

iTrader: (14)

I'm not seeing where comp lists the xfi lobe as only 6500 rpm capable. Are you talking about the xfi grinds they have for the trucks or something (around 218-224ish at .050)? This is their description right from comp's master.

XTREME ENERGY™ XFI™ HYDRAULICS
The Xtreme Energy™ XFI™ Series is designed for use with modern induction systems, heads, springs and rockers. The XFI™ intake lobes have more
lift than the base Xtreme series, and the XFI™ exhaust lobes have more area under the curve, for better exhaust flow, than the base exhaust series.
These are the first hydraulic flat tappet profiles designed for use with COMP Cams’ Beehive Ovate valve springs such as the #26915, #26918 &
#26120. The combination of these profiles, the new springs, and our very stiff Pro Magnum™ rocker arms in higher ratios, makes for the most revolutionary
improvement in hydraulic flat tappet design to date by bringing the latest race winning technology to the street.

1989GTA

Just reading the rpm range on their brochure. The XFI 242/248 rpm operating range is listed as 2200 to 6200. The 6200rpm seems a little low for such a big cam. I think you have proved otherwise with a good setup.

M2SPEED

I noticed that in Comp Cams lobe catalog the mention of “hydraulic flat” tappet design, but the area in the catalog and the main description states “hydraulic roller”. Is what they’re saying is that the XFI was originally designed as a hydraulic flat tappet lobe but it’s now redesigned as hydraulic roller tappet lobe?

DAPSUPRSLO

iTrader: (14)

Good question, it appears the rollers are quite a bit faster from .050 to .200 though (79 degrees for the rollers vs. 86 for the flat tappet, for the lobes I checked) so i'd doubt they are similar at all. I don't know if comp based the xfi roller off something they found in the xfi flat tappet and the only people that could probably tell you at comp aren't available to the general public it seems.

1989 GTA, wow, that is not much rpms for a cam of that size, interesting. Who knows what their reasons is for that. Comp does some funny things some time. The comp r lifters acceptability range of .002" pre-load is my favorite example, ha

SStrokerAce

iTrader: (2)

Yeah also the Jerk that's associated with any flat nose cam.... then again the XE-R and LSK both do this as well.

Good to see someone else here has some idea about all of this.

Bret