Originally Posted by Puck

Honest question, you really think only ~10-15hp was from the cam swap? XE lobes are very mild, surely the cam you specced is using quite a bit more aggressive lobes? (I'm not asking about them, I understand from a business stand point you can't talk about the lobes you use and spec...which would be way more insightful information then just knowing the duration @50). It also has a more favorable NA split, quite a bit more lift, and a healthy amount of duration. I can't imagine your larger, modern custom cam NOT making a sizable difference both under the curve and @ peak over the old lazy XE lobed 236/248 grind that clearly wasn't specced for big NA power on a stroker.

Like I said, it doesn't really matter since you provided a bolt-on PACKAGE that eliminates the trial and error, and the proof is right there that it works as a whole...I just feel you are selling yourself short on the benefits of a modern, properly specced camshaft.

Originally Posted by Rob94hawk

Are the stock piston valve reliefs enough to clear the valves with these heads? Probably wouldn't gain much with this swap anyway. Maybe 5hp.

Originally Posted by 1SlowFormula

I think there is a lot of potential in these heads, or anything 21* for that matter, I wonder what an all out LT1 with these and a good matching solid roller and single plane would do???

Originally Posted by Puck

The 21* TFS are badass heads still, and seemed to work more then good enough on this medium cammed 6500rpm 396, but just don't have the size to feed a max effort high rpm stroker.

Originally Posted by Advanced Induction

Haven't been able to get on the forums in awhile, figured you guys might like some answers.



Yes, it makes more area under the curve and average power, but the peak difference isn't going to be huge - the head is the biggest factor by far. Never heard a lobe described as "lazy," that strikes me as internet jargon from guys w/o data. I suppose there are people who consider the XE series mild, but I do not. How is the "split" more favorable for an NA application? How does one determine that from .050" #'s? I don't make a habit of selling myself short, but neither do I care to bullshit guys about how the cam makes all the difference in the world insofar as output goes. Unless something is out of the park w/ one grind, similar cams tend to make similar #'s if they are both under control.

Cams are simple - most guys just have no data. Most all of the cam companies have milder lobes than what is popular.





Depends on setup. CNC'd GM LT1's are a better choice for the majority of stock short block applications in my experience.



Same as a similar 23deg head. Nothing particularly special about a 21deg valve angle - it does not get you a quarter of the way to a 15deg sbc head, just smaller available chamber volumes. I do SR setups on the 21deg head w/ the .700" Nextek dual spring option listed on the site.



In all the years I've done this, I don't think I have ever had an LT guy truly want a max effort NA build. The overwhelming majority will never spend the $ on short block and valve train to run the current heads we offer run to potential.

I've offered to do a setup for guys who want a large 23deg, converted 12-18deg, etc. LT setup, but have never had the 5-8 guys step up and send in deposits to get something like that going.

Alan - so this is all Frank's fault, eh. Maybe that is just his devious plan to eliminate his competition - convince them all to invest in things that, half the time, keep them from getting to the events.

Glad you guys like it, take care.

-Phil