Bob, Jeff got my low end torque to mirror the torque the car produced when it had the other cam and FAST in it, at lower RPMs, then the torque improved over the previous setup past 3000-3500 all the way to the red line , as you can see by the dynograph I posted earlier.I'm not sure what low end torque they're talking of sacrificing, unless it's over a different, more expensive head.The torque my car has right now far surpasses what it had stock and is quite a bit more over the previous setup.My car pulls harder now over 3500RPM than any car I've owned before, including my SC'd 2000 TA w/547 RWHP.I'm hoping the strip numbers will verify my SOTP and Dyno gains. Bob, I can't remember what tranny you have, but if it's the M6, expect a bit more torque out of the identical package I have. If it's the A6, then thats what I have. A4 is about the same, maybe a bit more/less than the A6.

 

Congrats on your project.... Sounds like it will be a beast!!! Just enjoy the car regardless of what people say... 450RWHP is plenty to kick some tail!!!

I just wanted to comment on the FAST performance increase.. I gained nearly 2mph in the 1/4 on a heads and cam car.. From 121MPH to 123.5 from the addition of the Fast with tuning...

 

I have the same concerns about these heads. You can get a nice dyno curve if the tuning is on, but how is the throttle response at 1400 rpms in gear with that huge intake port? I've driven cars that look great on a dyno sheet that starts at 2500 rpms, but they don't drive anything like the dyno shows. In my driving, the engine spends 99% of it's time below the rpm range shown on the graph.

 

For people looking for a great top end for drag track use there isnt much of an issue. Get gears and head to the track. for peope looking for max low end street performance, look elsewhere.

Huge runners have always been better on strokers and in FI applications. These heads are ikely to shine on L92 6.2 liter motors so the 416 stroker or a forged 6.2 for a S/C will likely set new benchmark performance.

Just because a head bolts up doesnt mean that it is good to do so. Two tuners have make great low end power with these heads. One used a huge cam unlikely to make a smile on the daily driver crowd but one tuner got great low end with a 223 intake duration cam. All that means is that the best combo hasnt been found and you will likely need to notch pistons to make great low end power with a bigger cam. Expect a lot of shake with long duration exhasut lobes likely to be needed. The overlap also seems to be an issue.

I expect the 823 head with its bigger exhaust port will outshine the cleaner casting in time with proper porting.

Also keep in mind that the tuners getting great numbers are not using an out of the box version of this head. The ported versions are 1599-1799. That is exactly where lingenfelter and cartek's ported heads fit in cost wise. There is little trade off with many of these options.

I would also like to point out that with stock heads and their 10.9 compression, they make a better choice for power if your target is 435rwhp. Thats exactly what the stock heads do with a texas speed torquer 2. The cam is 232 duration last I saw. Why have a soggy low end with heads and a cam that barely do that power with issues in the low end? To experiment and find the cam that works to get to where tuners like DTE, TSP, and RPM motrs got to. With FI, they will shine since big runners are the rule.

Dont do this install because you think they are 350 dollar heads. After valves, springs, and NO porting they are still over 1000 plus the required L76. With all you need for a stock casting bolt on the swap will cost near 2k. Heavy valves float unless you have top shelf springs and that will cost 500-600 alone.

 

Without getting into too much of what and how we port our L92 cylinder heads- most of our power/torque is found in valve bowl/valve seat work, rather than simply "hogging out" the runners to make high end power at the sacrifice of low-end torque. Port configuration is vastly more important on these cylinder heads than physical port size. Match those new high velocity airflow traits of the modified cylinder head to a cam profile that suits the application, exhaust, induction, etc. as a whole and everything will fall into place nicely.

Bigger most definately is not better with these head combinations- at least for a street car. Building a max-effort drag car is a different animal altogether and these heads have the capability to make some silly power in the mid-to-upper end of the curve, where most drag racers like the power delivery anyway.



Regards,
Phil- DTE

 

Spin/Phil
Thanks for the clarification and insight

 

Thanks! Yeah, I was hoping for more out of the FAST, but it just didn't pan out. Could be that I was running stock heads, maybe it didn't compliment the stock heads as well as your aftermarket one. Who knows? Hadn't heard from you in awhile, X, always appreciate your input.Thanks again for the comments and like I posted earlier, I did this my way, for me , so I really don't care what the nay-sayers say, I posted so people who were interested could see results to help them make up their minds.

 

Just to give you some added input on the FAST; My LS2 motor was making 410rwhp/394rwtq without the FAST. With the fast it jumped to 425/405. But just adding the 215 ET heads it jumped to 461/435. I believe the FAST really makes aftermarket heads work at there highest level of efficiency. Anyway those were the numbers. I guess you guys can guess, I didn't do everything at once. It was kind of an evolution in stages. It gave me good intel about each component part. Kind of a test bed so to speak.

 

Yeah, I gained 16 rwhp( inline with your first statement), I was making 406 at the time and it bumped to 422. I only gained like 4-5 tq though. The reason I wasn't happy with the FAST wasn't the dyno gains , but the lack of gains in track and road performance. I guess we can assertain from X's and your post as well as with my experience, the FAST is a great mod, but works best with aftermarket heads.

 

OK EVIL

here it is . . .


Your next MOD . . . .

 

You are killing me JFT!

 

I try. Most folks take this stuff way too seriously.

 

I was actually hoping to put some stickers on, a giant wing, and neon lights for another 100 rwhp, but for now, the L92 will do....

 

Hmm. I just had a thought. What about...wait for it....wait for it....L92 and L76 badges?!!

YES! YES! YES!

 

I dont know jack about the bowls of the L92, I just bolted the stock untouched heads because I had nothing to do and I will fire it up tomorrow.

I hope I didnt lose anything down low 3k wise. I needed the drop in compression.