Rich-L79

I recently put on AFR Enforcer heads and put in a Bullet Cams 218/226 cam. I already had a FAST 102, 92mm NW TB and JBA shorty headers.

The green line is before the heads and cam. Found out I do need bigger valve springs if I want to turn over 6100.

RB04Av

In a general overall kind of way, that seems to be the way of things with these motors.

Even in stock trim the heads flow FAR better than what we've been accustomed to in the old days. Used to be, to extract every last possible molecule of flow through the valves, we had to cam motors up to the moon, especially the duration. These, not so much. The need to sacrifice street "quickness" to get high-RPM power isn't as demanding as it once was. For that matter, even in the old SBC, you could get THE SAME power with really good-flowing heads and less cam, than with stock(ish) heads and a YYYYUUUUUUUUUJJJJJJJE cam; and not have to give up street manners and gas mileage and all such as that, into the bargain.

Looks to me like you got A SHIPLOAD of horsepucker there, without giving up off-idle torque, and in a useable STREET RPM ranges besides. A win-win in my book.

Not surprised better valve springs helped. Since the 70s they've been a limiting factor to performance. IMO there's almost no such thing as "too much" valve spring; butt people, for some reason, always want to run the absolute least possible spring that the "book" says will "fit", even if it doesn't actually control the valve. More spring will even make an otherwise totally bone-stock motor, manifolds and all, run better, than stock ones.

Rich-L79

I should add, this graph is STD, SAE was 396/393.

the_merv

iTrader: (88)

Long Tube Headers will get a good gain, something to keep in mind for the future.

Rich-L79

Yeah, I have long tubes on my 06. When I went from shorties to long tubes on it I gained a whopping 9hp (and I did 1.8 rockers at the same time so not all of those 9hp were in the headers). For ease of install and maintenance I'll stick with the shorties on this one. Shorties with good mids do a lot better than most people give them credit for doing.

ThomasJohnson

Thanks for the information.

G Atsma

Here we go again......

Kfxguy

iTrader: (1)

Don't put "bigger" valvesprings. Put stronger valve springs, but if you keep them smaller diameter and lighter weight, the engine will rpm more and won't lose efficiency that much stronger and heavier springs will sap away. I learned this the hard way. Had a nice, lightweight valve spring package that would rpm past 7800 in a 383 cu inch old school SBC. I decided I wanted more power so I went up 12 degreed duration on the intake and 4 degrees on the exhaust alonf with much larger and stronger springs. I actually weighed the difference of the total weight of the springs and retainers and the difference was over 5lbs, which is crazy. I did not consider at the time that springs have to control their own mass too. So pick wisely and it'll pick up more power on the top end without killing power elsewhere. Springs do cost power....

Rich-L79

Springs are the same diameter, just stronger. They were a direct swap for what I had, reused the same cups, retainers and locks. Came from AFR. It now revs well up to my rev limiter limit of 6700 without issue.

autogeek23

iTrader: (13)

maybe i should ditch the Trex and get a smaller cam since im running stock 243s......

99 Black Bird T/A

iTrader: (4)

Thanks for sharing the build, details & results. I found it very interesting.

Rich-L79

Runs better now with the stronger springs, no valve float or dramatic power drop above 6k.

Here's the latest dyno run.

the_merv

iTrader: (88)

Who does the tuning? It's not mentioned here.

wannafbody

iTrader: (2)

This really depends on what the car is doing. For a street car, the small cam is probably a good choice. You really didn't lose any low rpm torque.