may sound like a noob question, but would a tune be required after installing 1.8 roller rockers?

 

couldn't hurt

 

With the 1.8's, you're effectively making the cam bigger because of the higher lift. So, yes, you'll get the most out of the new rockers by getting it tuned.

 

a tune isn't required for the rockers. not only are you affecting lift, but you are also affecting duration at the valve.

 

Well, you do increase the effective duration 1 or 2 degrees once the valve is off the seat, since you're accelerating the valve more quickly, so in practical terms, you're right, but the ratio change itself does not alter the timing of any valve events.

And if I wasn't clear, no he doesn't have to get a tune, but he'll benefit a lot more from the better rockers if he gets one.

 

Correct it does not affect the initial opening and closing events. Just all in between.

 

however if youre increasing duration youre increasing airflow throughout the engine, id say yes you need a tune cause it no longer knows how much its getting.

 

Now this is just a rough explanation. The maf and map sensors Monitor the amount of air coming into the engine. That dictates in the fueling and timing tables. Then the o2 sensors Monitor how much fuel is unburned then make fueling changes from there.

Minor changes to the motor, the pcm can make changes to. Major changes like cam and heads will require a tune.

 

we know the PCM will go for whatever stoich is programmed, which is based of 02 feedback, however if you start increasing airflow (headers, rockers, IM swap etc) beyond what the VE and MAF tables were originally programmed you start defaulting to low octane spark maps and in general not getting the performance you should, i understand if you dont have a way to tune and want your money to spent all at once but if you have a way to re adjust your maps, it would be more beneficial.

 

When I get home tonight I'll post my dyno going from stock 1.7 to crane 1.8 rockers did with no tune

 

Actually just found the one off of vinci high performance website of an 06 impala ss swapping from stock to 1.8. No tuning. Point is not required.
2006 IMPALA SS D.O.D. DYNO RESULTS
STOCK "NO MODS" VS. VHP 1.8 ROLLER ROCKER / VALVE SPRING PACKAGE
CAR RUN IN 2ND GEAR TO PRESENT LONGER GRAPH TIME. NUMBERS HIGHER IN 3RD GEAR

 

i got those 1.8s didn't know it was that much but very nice

 

Very nice, this Dyno didn't show afr 's and we don't know the timing. I'm pretty sure you could pull way more out of it with the tune, however great runs.

 

hey 91 i put just rockers on but no springs ,should i correct that and whats a good part # thank you

 

thanks for all the replies guys. and i was planning on getting it tuned, just didnt know if i needed it tuned to get it running. and on vinci performance, what valve spring kit did you end up getting?

 

in that dyno those were crane valve springs. vinci has since migrated to yella terra and these springs

http://vincihighperformance.com/LS1%...%20REDONE.HTML

 

Tune wouldn't hurt

 

I recommend that you just call vinchi performance, they have great customer support.

 

you can still retain the DoD when doing 1.8 rockers correct? forgive the noobness, i just picked up my GP GXP 2 nights ago.

 

Correct.