Are these the most aggressive lobes for the LT1 w/ Hydraulic Rollers? I am thinking getting a custom grind using these lobes if they are the best out there. 6k shifts on an a4 w/ stock heads. 68k on the engine.

Can I use my LT4 (crane) 1.6 self-aligning roller rockers (7/16 stud)?

Are the 918's the best spring to be used (lift for the lobes I will probably use will be in the .560 area w/ 1.6)?

 

depending what XFI u go with, you'll be over .560, the XFI468 is around .560 w/ 1.5RR i believe

 

I have just fired up my new motor with the XFI268 cam. It has a .570/.565" lift with 1.6 rockers. This is with a L98 modified TPI set up. I'm just in the process of breaking in the new motor.

However I can tell you it idles quite nicely at 750rpm. Better than my old ZZ9 cam. The throttle response is quite brisk with no lag. Has between 14 and 15 inches of vacuum. Closer to 15. Very happy with it at this point. Can't wait to get some miles on the motor and get the car on the dyno.

Are there better lobes? You might want to check out the LSK lobes by Comp Cams. I think you have to go the custom route to get those.

 

That's with 1.6 RR.

I'm going to use one of these cams for my new 355. Several issues have been brought up about them and how they're hard to control over the nose. I'm sure Bret will chime in here. Search in the Advanced Tech section. Which lobes were you thinking of? The 230 or higher duration will definitely require more than 6k rpm shifts. These cams like a lot of RPM, hence the difficulty controlling them.

 

Why bother to put a cam in and limit the motor to 6k? I never did get that. And if you have to limit your rpms you might what to make sure you have the right cam to work within your guidelines.

 

I'm not limiting the cam. That is just the rpm range that I want to have the most average power in. If it makes good power to 6200 then I'll rev to 6200. From the range I want to operate in on EA Pro most of the cam profiles I am playing with die off after 6k. I am not willing to sacrifice average power to make 10 more peak etc.. Car is an a4 which is the reason also for the lower revs since I am not planning on running gears or a big stall.

 

Yeah, everyone seems to love the xfi and I probably will to as I like the extra lift and quicker ramps. Can you use LSK lobes in an LT1 with stock hyraulic lifters? Would it be beneficial or kill the valvetrain?

 

Man, you are opening a can of worms here your not going to get right. EA Pro can be a blessing and a curse espeically if your model is way off.

There are a lot of things you CAN'T do physically. LSK lobes on a SBC/LT1 core being one of them.

Getting a hyd roller to run well over 6000rpm isin't hard at all.

Bret

 

I have an LT4 396 stroker w/ AFR 195 heads and I'm running the largest Comp XFI (292XFI) W/ 918 beehives, Crane S/A 1.6 RRs, 3/8" custom push-rods and Crane performance roller-lifters. Brian at PCMforLess did the tuning and set the shift points around 6500. I'm very happy with the XFI cam and my complete engine package (power band and overall performance).

It currently runs low 11s (all N/A) with some tractions issues due to the small ET Streets. I'm going to 28" slicks and 4.30 gears this season and hope to have the car around 11 flat, or possibly 10.90s.

WD