What cams?

[zach_ae86]

What are the largest cams I can run in stock ecu and valve springs? At what lift should I upgrade valve springs? in the middle of rebuild 10:1 forged piston stock crank godspeed hbeam rods, stock big port, head stock ecu. I want to run bigger cams as well as adjustable cam gears what cams should I run?

[strmrdr23]

i think 264 are the biggest you can go with stock ecu.

[yoshimitsuspeed]

i think 264 are the biggest you can go with stock ecu.

I hear this all the time and in the exact same manner every time.
"I heard from a guy one time who read on the internet that someone else's buddy thought that you could only run 264s on the stock ECU"
I woould love to find the guy who actually did dozens of tests in dozens of different configurations to prove it wasn't possible and exactly what the ECU did that made it "not work".

I have a customer running 264 poncams with a wideband and he had to lean out the motor to get the AFRs more optimized.
Others have run 150+ WHP boosted on the stock ECU which is considerably more airflow than 264s alone can deliver.

I believe that this theory probably started with someone smart suggesting that it wasn't practical to run much more than a 264 cam. A 264 will put peak power pretty close to stock redline. This means that more cam will net you the most gains outside of the ECUs capability so you wouldn't see gains where you can reach them but may loose some power where you regularly use it.
If you were going to throw in some big cams with plans on going high RPM and engine management in the future I suspect the stock ECU wouldn't have much trouble with a bigger cam. You just wouldn't be able to unlock it's potential.

I also wouldn't run more than 264s without a compression increase. Personally I wouldn't do cams at all without addressing compression. That is what really wakes cams up and gets the most out of them across the entire rev range.

If you want a nice easy bang for the buck drop in cam it's hard to beat the Poncams.
http://www.matrixgarage.com/?q=products ... 64-81mm-ex

If you want to go any bigger than that I would recommend getting a wideband so you can monitor things and tune if needed.

[Jimmee1990]

I had 280 degree 8.3mm lift cams on a stock smallport 10.2:1 bottom end with a standard bigport head, standard map ecu and only other supporting mods were removing the butterflies and shafts from the TVIS plate, a pod filter in an airbox and good 4-1 headers and a hks hi-power. Mine made good power right up to the rev limiter at 8000rpm, and the AFR's were fine if a little rich in the mid range.

You're right in saying it didn't reach the higher potential for the cams as it was still pulling very well right up to the limiter and easily had another 1000rpm left before it ran out of puff, in saying that it was still better everywhere in the rev range than it ever was standard so I would highly recommend it even on the stock MAP ecu.

[yoshimitsuspeed]

I had 280 degree 8.3mm lift cams on a stock smallport 10.2:1 bottom end with a standard bigport head, standard map ecu and only other supporting mods were removing the butterflies and shafts from the TVIS plate, a pod filter in an airbox and good 4-1 headers and a hks hi-power. Mine made good power right up to the rev limiter at 8000rpm, and the AFR's were fine if a little rich in the mid range.

You're right in saying it didn't reach the higher potential for the cams as it was still pulling very well right up to the limiter and easily had another 1000rpm left before it ran out of puff, in saying that it was still better everywhere in the rev range than it ever was standard so I would highly recommend it even on the stock MAP ecu.

Awesome info. Thanks for posting up your experience.

[gotzoom?]

I'm running something similar to Jimmee. I have smallport 10.1:1 pistons and Poncams with otherwise largeport everything. I cleaned up the bowls and matched the exhaust ports, as well. It runs happily on 89 octane fuel and pulls all the way to rev cut.