Needing Input for my Future LQ4 Build

[SMWS6TA]

I doing this in a thread instead of just PM'ing FirebirdJones because I would like others opinion's and info for this build. As some of you know I just acquired a LQ4 short block. I've only just begun to research possibilities for it.

My near term goals will be to get it built to a solid NA motor with possible future 408 FI build. I have no plans for NO2 but doesn't mean with this motor it's not an option.

So far I'm thinking about getting LS2 Pistons, LS6 P&P Oil pump, L92 heads, LS3 or L76 Intake (till I can afford a FAST 102)

CAM - not sure yet, with the LS1 I wanted a MS3/4 with 243 heads but with this one not sure if the MS3/4 would be a good choice with the L92 heads. I want something that thumps. I want a very solid mid to high 400's or higher in HP to the wheels.

With the right cam and the L92 Heads and the LS3/L76 intake I should be in the higher 400's right? Any suggestions?

I know if I get to do a 408 FI build in a couple of years I'll have tear down the whole motor and have it bore 30 over and get all new pistons and crank and possible need a different CAM. That's fine with me and I'll add it to the cost for a FI build.


In my signature is all of my current mods to the car. I am currently building an 8.8 rear with 4.10 gears. This engine build will come after I have finished the rear and send the tranny off to Tick Performance for a rebuild.



Other questions I have:

I know my QT Bell Housing and tranny will work with the LQ4 but I'm wondering if the headers will work with the L92 heads as well?

Will I be able to use my coil packs from the LS1 I have?

Fuel issues - I'm planning on a New Racetronix pump, but what fuel injectors would be needed?

Will my 98 PCM be able to be reprogram to work with the LQ4?

Wire harness - what will need moving/added or extended?


Thanks ahead for any input

[My00Z28]

So do you have the pistons and rods with the lq4? if so they are really not bad the only thing is they are dished unlike the ls2 pistons...

You talk about doing a 408 FI build and if you ask me(being a college student) cheaper is better so i wouldnt sink a lot of money in to the mild factory lq4 build because i would want that in my 408!
when it comes to cams i picked the brute speed forced induction cam because im planning on boost right away and the cams numbers look good for my plans.. Tv2 and ms3/4 have put down great numbers and 400+hp will be easy with either!

i do not know a lot about the l92 heads besides that they are square port heads and the ls9 cam is designed for heads like those...

Factory ls1 coils are better than most think and should handle the most of what you throw at them!

if you want to spend money once on fuel system i would prep for boost. twin-in-tank walbro 255s are what im going to run with a boost ref. sensor to turn on the second pump. fuel injectors for NA i would say about 42lbs and for boost 80lbs+...

as for PCM i think the 98s were the problem children of the LS family... you can use it with an LQ4 but you must use the engine harness from the 98 engine!

Wire harness should not need to be changed because you will use your old one! but the lq4 block does not have the hole drilled and tapped on the bottom like your ls. so either that will have to be drilled and tapped or you move your alt to the top of the engine!

[pajeff02]

Subscribed. I would get a later model PCM to run this beast -- I believe Frost has them for sale on his site.

[My00Z28]

I don't think he can just run a new PCM! He would need to change more like his gauges. Idk check this thread out... http://www.ls1.com/forums/f6/1998-ca...engine-162747/

[SMWS6TA]

So do you have the pistons and rods with the lq4? if so they are really not bad the only thing is they are dished unlike the ls2 pistons...

You talk about doing a 408 FI build and if you ask me(being a college student) cheaper is better so i wouldnt sink a lot of money in to the mild factory lq4 build because i would want that in my 408!
when it comes to cams i picked the brute speed forced induction cam because im planning on boost right away and the cams numbers look good for my plans.. Tv2 and ms3/4 have put down great numbers and 400+hp will be easy with either!

i do not know a lot about the l92 heads besides that they are square port heads and the ls9 cam is designed for heads like those...

Factory ls1 coils are better than most think and should handle the most of what you throw at them!

if you want to spend money once on fuel system i would prep for boost. twin-in-tank walbro 255s are what im going to run with a boost ref. sensor to turn on the second pump. fuel injectors for NA i would say about 42lbs and for boost 80lbs+...

as for PCM i think the 98s were the problem children of the LS family... you can use it with an LQ4 but you must use the engine harness from the 98 engine!

Wire harness should not need to be changed because you will use your old one! but the lq4 block does not have the hole drilled and tapped on the bottom like your ls. so either that will have to be drilled and tapped or you move your alt to the top of the engine!

Here are some of the pics I took.










So far I going to get it broke down and take it to a shop that can acid wash, install new cam bearings and check the block out so I know before I invest any more money into it. They should also tell me if the block will be able to handle getting bore out. I rather be out now then later.

[My00Z28]

O ya it looks like it needs a real good cleaning and at minimum a hone!!!

[SMWS6TA]

well I've been reading a lot lately about LQ4/9 builds. It seems like it is all over the place.

Some of the issues I've read are like what I said in above post. The low compression of the LQ4's. It's great if you are going to do a FI build right away, but for NA builds it means some work and a lot of homework. For those that don't know the more compression = more HP a NA motor can make. For FI's you want lower compression because the turbo/supercharger will make up for the low compression.


So this is what I've discovered - If I want my LQ4 to make more compression I have a few options.

1) Swap the LQ4 pistons for either LQ9 or LS2 pistons and rods. LQ4 and LQ9's both used the same crank. LS2's I haven't confirmed it yet but I believe so. Swapping the pistons over to one of these 2 will bump the compression and let me have more options with the cylinder heads.

I can get stock LQ9 pistons for $43 ea and new LQ9 rods with floating pins for $46.70 each

This option will give me a choice of any style head and cam I want.

2) If I keep the LQ4 pistons I will need to drop serious coin into 799/243 heads and have a PRC stage 2.5 or better. this will also bump the compression while leaving the pistons alone. With option 2 you also might have to fly cut the LQ4 piston heads due to piston to valve clearance. This option will limit what style heads and cam I can run.

3) Cost much more - bore out and do a complete 408 build with new everything.

[My00Z28]

well I've been reading a lot lately about LQ4/9 builds. It seems like it is all over the place.

Some of the issues I've read are like what I said in above post. The low compression of the LQ4's. It's great if you are going to do a FI build right away, but for NA builds it means some work and a lot of homework. For those that don't know the more compression = more HP a NA motor can make. For FI's you want lower compression because the turbo/supercharger will make up for the low compression.


So this is what I've discovered - If I want my LQ4 to make more compression I have a few options.

1) Swap the LQ4 pistons for either LQ9 or LS2 pistons and rods. LQ4 and LQ9's both used the same crank. LS2's I haven't confirmed it yet but I believe so. Swapping the pistons over to one of these 2 will bump the compression and let me have more options with the cylinder heads.

I can get stock LQ9 pistons for $43 ea and new LQ9 rods for $46.70 each

2) If I keep the LQ4 pistons I will need to drop serious coin into 799/243 heads and have a PRC stage 2.5 or better. this will also bump the compression while leaving the pistons alone.





I'm not finish with this post, I'll have to finish it later.....

Run lq9 pistons and leave the rods. Or get new heads like stated...

[SMWS6TA]

Run lq9 pistons and leave the rods. Or get new heads like stated...

you didn't let me finish.

[My00Z28]

you didn't let me finish.

I know I was just saying for what you had so far lol

[SMWS6TA]

So so you think the LQ9 pistons will work with the the LQ4 rods?

Will I need to get the crank checked for balance after the piston swap?

[My00Z28]

I think it depends on the year on LQ you are using

[SMWS6TA]

It is from a 04' 2500 Silverado.


I read a couple of threads on tech yesterday and today. One I know you replied in. (the guy that went back and forth about cam/heads and then ended up getting a 5th gen)


For a while his confused the hell out of me then after reading other stuff I realized he just didn't know what he wanted.

[My00Z28]

Not sure what thread ur talking about but I think mid 2004 engines were full floating set ups....

[tatertot91]

I like the idea of option 2 but if FI is really on your mind i'd go a different route. Spending that much on a set of heads to have to get rid of em for a FI build later on is a waste imo. If thats really on your mind i say save some and get your 8.8 build finished and then get going on a stroker

[SMWS6TA]

sorry I got you mixed up with pop6482. He's doing a LQ4 swap into a 3rd gen.

[MudStainKILLA]

SMWS6TA,
Hey just to give you a ball park on prices about 2 months ago while still in afghanistan i was emailing wiseco about putting together a forged 408 RT ASSY. everything came out to 2300 and some change, crank, rods, pins, pistons rings all pre balanced from them and shipped. Not sure if thats outta your price range or not man.

As for your headers/ heads working together i asked that a while back and you should be fine to reuse them.

[SMWS6TA]

Thanks. I'm still in research mode on this.


My 8.8 build is the priority now. Once I get the sleeves and weld up everything I can move on it again. Now that I got this block waiting on me I'm getting a little impatient, I want it done and installed so I can play....But good things come to those that wait....or so I'm told.

[jrbonds]

And here I am wishing I had a good rear and some gears to wake up my lq9.

[MudStainKILLA]

Ya i subscribed to that 8.8 build thread of yours, can't wait to see the outcome!