I want to build an LQ9 for mild street performane and "decent" economy (20 mpg highway if possible). My original plan was to use an LS6 cam and intake in an lq4 that I will make an lq9 by changing pistons and keeping the lq4 heads. I'll be using a 4l60E trans, and I have a Ford nine inch rear end geared 325. My questions are: am I dreaming or is this possible? If so how?
can I go bigger on cam and still hit my goal?

 

Look at the build in my signature. I get around 22-23 mpg highway. My cam is big as well. Very similar to a MS3

 

When I swapped out my hydraulic roller 454, Super T10 and 4.10 gears I purposely went with a 5.3/4L65E/3.25 combo. Everything I heard about 6.0 was bad when it came to fuel economy including the 2003 extended cab 4wd that I owned for a short time and replaced with an old style mechanical injector 24v diesel Cumins. 16 vs 25 mpg.


The 5.3 comes with the smaller turbo 350 based 4L60/65/70E series od auto. With a 6.0 I think most people would recommend using the turbo 400 based 4L80E which it is usually mated to.


I could care less about a bit of extra power on the street.

 

What vehicle is this build going to power? Tire size?

 

1991 camaro RS, and tire size is 245/50/16

 

Well I did a little more digging and I called TSP to get their take on my idea, and they said to go with LQ9 pistons, 243 heads (11:1 CPR), 224R cam, ls6 intake, long tubes, and cold air intake. The guy didn't really have any MPG numbers but he said "they should stay about the same" so I'm not really sure what range I'll be in, far as HP he said I'll be hitting in the 400 range. What you guys think ?

 

Depends in the dyno, your stall, etc...but i'd say around 400 hp as well

 

what size stall should I use? TSP said I could use a stock converter but I think I need more than that.

 

Well before addressing anything else, you mentioned wanting around at least 20 mpg highway. You do realize you can go with a bigger cam and make a good more amount of power and still hit that goal right?

 

I did not, what all is involved?

 

Same thing involved as going with that 224 cam that TSP mentioned, but you can run something a little bigger along with a 3600-4000 stall. If it were me id consider a cam more in the 228/232 range along with the aftermarket stall. Nothing wrong with the 224 cam and stock converter, but if you are going through the effort, why not add something that packs a good punch. Know what I mean? Did TSP reccommend that cam assuming that you wanted to keep the stock stall?

 

stock stall was never a requirement and i did mention that to the guy but he never gave any other numbers. And I agree completely, better to do it right the first time. And ok cool so do I just need to search for 228 or 232 cam?

 

Well I'm just saying I'd personally pick something that general range. A lot of this is personal preference as well, so it's not like there's one best choice here. With your mods, compression, gearing, etc...i just think a cam in that range with a good stall would be your best overall bet.

 

I understand. I'll do some more digging and see what I can find. I'll keep this thread updated with what I decide. Thank you for your help it' much appreciated.

 

No problem, glad to help. I'm sure others will chime in as well, and have different insight and opinions.

 

I hope so. I want to learn as much as I can

 

Can i use the ls1 harness on my LQ9 with the ls1 intake on it?

 

yes you should be able to just fine.

 

Why are you wanting to get 20 mpg highway? To save on the cost of gas?

 

well I said 20 cause I didn't wanna shoot to high but yes I want to save on gas cost