Well i think i have about taken th e4.8 as far as i want to go... I got the idea last night to swap in a 6L this summer, maybe... I want to go with a 224 XER cam. I am wanting something is alot of midrange power, since that is how i drive 90% of the time, i rarely go over 4500rpm... I am not really interested in making a track monster yet, just a good DD... i will probably rework the exhaust a little bit later on...

so my question.

LQ4 with my PRC 2.5 862's (58cc), with the 224R, the CR would roughly be 11.0

or

LQ9 stock heads, with the 224R... and sell the PRC 2.5s i believe the CR is 10.0?

both configurations will roughly cost the same, since the LQ9's carry that premium, but i could sell my current heads.... so it is a wash... I am jsut slighltly hesitant on running 11.0 CR...



So what would you do???

 

You saw the LQ4/224/PRC dyno thread, enough said

Plus its what you want for your eventual CC anyway...

 

Am I in a time machine? But seriously I'd run an LQ4 with the stock heads milled like I did. People think the LQ9 is twice as much a the LQ4 for some reason..

 

What's the cutoff on premium gas as it relates to C/R? Cause if 10:1 req's it, just go for the 11:1 C/R. In that case, option 2. Isn't ~10.5:1 a good starting pt when premium is required? Of course, depending on a variety of variables: cam, tune, so on.

 

I ran 11.2:1 in my heavy *** truck on 93 with over 30*s of timing with no problem. I was running a pretty big cam in my 418 though so it bled some cylinder pressure(237/242 112).

Since youve already got the heads Id run em, plus you can sell the stock heads for the money it will cost for new bolts and gaskets.

 

I'm sayin when do u need to get away from regular gas & step up to premium?

At what compression ratio?

 

Yep, i have ridden in David's truck many times, i loved his low/mid range TQ. And those heads IMO helped on the topend. that is why i want the 224.

oh and about the CC....

I believe when i do finally step up to the CC (when little BlackGMCs start being developed), it will be a 04-05 DMAX!

yep i am planning on copying your previous setup.

yep i will have to play with the LSA and ICL to try and get the cylinder pressure down to a reasonable level...

IMO, alot of factors come into play with your question. For example, my current setup is 10.3-4 CR with ~ 8.5DCR. i run 89 octane ... Intially i was getting KR in the low rpm/high load areas and at WOT, but with COS3 and table B3647 (commanded fuel vs RPM), i just richened up the map/rpm areas where i was getting KR and richened up WOT map/rpm areas and it solved my problems...

 

 

yep lots of practicing going on

 

Yeah and to think I breathed a sigh of relief when he said he might not have kids

I think youre on the right track Corey, I bet with your super tuning skills you could get 364 cubes down the quarter pretty quick and probably even get better mileage that the 4.8