LS1 pwrd NOVA

iTrader: (2)

This is mainly a street car, daily driver not a race car.
Which engine would make more power on 93 octane only?
I have a single t4 s473 bw turbo with 3” or larger down pipe.
I have both engines and both are stock except the lq9 has rectangular truck heads on it. I have an ls6 and ls3 intake setups for each engine.
I’m sure the stock cam with the rect heads isn’t idea but I’m trying to see what’s the better way to go.
The rest of the car is a 69 camaro, t56 tranny, and what ever gear ratio is needed.

I know it’s not really Apple to apples but my main question is will the ls3 heads be better for a turbo setup? If a cam is needed for both to say one will be better than the other. I’ll add the cam or do you think both will be about the same hp and torque with the turbo I have?

Lsxford

iTrader: (6)

There will be little difference IMO. There is a difference in compression between the 2, but once you add boost its prob negligible. Out of boost there will be a slight diff. A cam will be a must.

If you have both engines see if either has gen 4 rods. If neither does id use the lq4, if both do id use the lq9, and obviously if only 1 does use that 1.

LS1 pwrd NOVA

iTrader: (2)

But will the gen 4 rods be a big difference or more for reliability in the long run?
I was hoping the rect heads may add a lot more power like in a NA application.

jordoza

The gen 4 rods hold more power before they bend. If one or the other has gen 4 rods go gen 4 rods for sure. Yes the rectangular heads will flow more which will make it easier to make more power. If you have a higher power engine to begin with boost will make more power if everything is right. I would for sure get a cam speced for the ls3 heads if i were you.

JoeNova

If the one is a true LQ9 with flat top pistons (no valve reliefs) and rectangle port heads, its the clear winner. It'll have gen 4 rods, more compression, more flow. Stock rectangle port heads and LS3 intake are all the flow you'll ever need.

LS1 pwrd NOVA

iTrader: (2)

Yea it is as I pulled it out of an 03 Escalade thst wrecked.
It still has the 317s on it but I have rect port heads for it. I just put less info in the first post about the lq9. Makes it easier vs people saying this n that.
I know it will need a cam made for an ls3 to get the best out of it.

But under “ boost only “ and 93 octane, will the lq9 with rect heads be a big difference or minor difference over the lq4 is what I am trying to figure out in a street configuration. Not looking for all out drag race power.

jasonsnova

my nova has a 6.o with rectangleheads, t56 and a s475 turbo and is a animal.
that being said if they are 03 engines they are probally gen 3. if you push them much past 650rwhp you will noodle a rod( ask me how I know).

jasonsnova

the 73 mm turbo is a bit small for a 6.0 , but the limiter will probally be straight 93.....so probally be limited to 12ish lbs of boost

gametech

iTrader: (1)

The LQ9 LS3 rectangle head combo is the hands down winner for a street ride. Don't let anyone tell you the turbo is too small. Big HP numbers win races, but insta-spool with off boost torque makes a street ride fun. If you are building a street ride, don't trade all of your drivability for a few hundred extra HP that your radials will never put to the ground.

jasonsnova

i tend to disagree.....my ls3 headed 6.0 with t6 s475 is perfect. I firmly believe you need a little bit of lag to hook up a street car. other wise you are gonna blow off the tires quick and run out of steam on top......im not saying you want boost coming in at 5k....but I feel 3500 is a good happy medium. Also remember if you start building boost at real low rpms it' very tough on the lower end

gametech

iTrader: (1)

Fair enough. Everybody has fun in a little different way. Just giving an opinion. However, if you need lag to hookup, you need better right foot control. Regardless of the general internet concensus, there is something in between idle and WOT.

jasonsnova

what fun is that ! lmao

LS1 pwrd NOVA

iTrader: (2)

It’s like this... I have both engines, the lq9 needs the square heads put on but if I mild cam them both and with every thing else being kind of equal externally.

Is the lq9 with square ports going to be a big difference vs the lq4?
Or are we talking very low difference in hp and tq between the two engines?
They say flow doesn’t mean as much on boosted engines unless your going big numbers.
But just say, the difference is around 25 hp more, I may leave the lq4 in it stock for now.
If it’s a bigger difference let’s say closer to 50 hp, but that’s with both engines having a mild cam installed to be a fair comparison, I may just do it then.

LS1 pwrd NOVA

iTrader: (2)

Jasonona what hp you put down on your setup?
You on e85? Any 93 octane numbers on any of your setups?
I will probably upgrade my turbo but I am going to use what I have now and then see what I wanna do next.
I’ve seen people upgrade and change everything up to on,y be disappointed with how much money they have re spent to gain minimal hp and tq.
An s475 would be a plus in my game plans though over all

jordoza

You havent stated any hp goals or i didnt see them but i doubt youll be disappointed in the s473 on a street car unless your like some of us sickos that think 600 to 700whp is only a good starting point for a daily driver. Be honest with yourself having 600whp is awesome and it can get old driving a 1000whp car that feels like it wants to kill you all the time. Or maybe im the one getting old. Who knows. All thay being said im putting twin billet s480s on my in new forged lsx going my "street car" so maybe not to old.

tiznodd

iTrader: (4)

It's my understanding that all LQ9's came with gen 4 style rods. LQ4's had the transition in 2005.

jasonsnova

you may be right but I would defiantly verify it has gen4 rods.

I havent had my car on the rollers yet , it' currently on a 12psi spring and it will creep up to 15ish psi before settling back In to 12. based on past cars we've had pretty safe guess it' around 700rwhp give or take.
I can tell you at 18 psi it will destroy 315 tires in 4 gear at 75mph rolling it to it.
car is on 93 + 50/50 water meth

LS1 pwrd NOVA

iTrader: (2)

Jordoza... at 1st I was just wanting a true 500 rwhp on pump gas 93 in a stock lq4 long block for this street car. This lq4 only has 93k miles, as I pulled it from a wrecked truck I bought at my work. I don’t want to hurt this engine as it’s clean and perfect, so I’m thinking 500 is a good goal, to keep it in one piece. It would have perfect street manners being stock.
Now I’m just thinking whatever I can get out of 93 pump gas, I’ll stick with until I decide what I want to do next to the car. I hope I get closer to 600 but like was posted, 93 pump gas will hold me back. Maybe I’ll throw a meth mix but how much could I gain with that?
I’m sure “next” will be a lot more power closer to 750

Jasonnova, I like that info on your car hp estimate...
maybe I’ll build the lq9/square head up after I finish the build. Depending on funds.

Lsxford

iTrader: (6)

So its completely stock lq4 vs lq9 shortblock with ls3 topend? If so IMO there will be significant gain with the lq9 and ls3 heads vs lq4 with 317s. I thought we were talking about lq4 with ls3 heads vs lq9 with ls3 heads. Basically i thought we were comparing shortblocks.

LS1 pwrd NOVA

iTrader: (2)

Yes sir, a stock lq4 long block vs an lq9 with square truck heads and ls3 or square truck intake as I have both intakes. ...
** But... with square heads, I was reading on here, the cam should be changed to get the best from the square heads. **
So to make it a fair or fairer comparison between the two engines, if the stock lq4 had a mild cam similar to an lq9 with square heads setup and a mild cam, would there be a big difference between the two “ under boost only though? “
If you guys think it’s a pretty decent amount difference between the two, roughly how much difference?
It’ll help me decide to spend the money into the lq9 being as it’ll be worth it.