dizwiz24

I got into a disagreement with a fellow ltx owner recently.

He claimed the lsx is so superior to the ltx for modding in every case.

I agreed with him that for n/a builds then yes it is. The heads/intake design are that good.

But for forced induction builds, that the gap between the two is closer. Ex. If I have a 18 psi boost solid roller 396 ltx making 900 rwhp and an 18 psi boost lsx making 950 rwhp then so what. Whoever wins the race is going to come down to other factors such as skill, tires, gears, vehicle weight, etc...

Yes, the lsx pcm is way easier to tune and the aftermarket support way better.

Overall though, I was trying to convince him its not worth it to do an lsx swap (on c4 corvette) if his eventual goals are forced induction. Even for the weight svings . Heck the steel ltx block is preferred (yes though I know there are lsx iron block truck motors).

Who's right? Worth swapping to lsx for forced induction or stick w ltx forced induction? Remember this is on a c4 corvette where the swap may not be as easy.

97FormulaWS-6

I'm doing a similar debate (In regards as what I want to put into my car when I put her back together in a couple years), and from the information that I've gathered... the LS based platform does handle boost more efficiently just due to the design. Therefore you will make more power with similar modifications/price with a LS based motor than a LT based motor.

dizwiz24

What parts of the design make it better?

I know the heads/ intake are giant leap beyond LTx technology. PCM is great too, but of course we can add an aftermarket megasquirt or DFI.

We also have AFR and trickflow castings where AI and LE do great work to make them perform.


Ill agree that for a high compression N/A road race motor, the LSx wins hands down. Especially with the weight savings.

Ill also agree that a similar mod'd FI LSx is going to make more power, but how much more power?

Is that extra power worth the hassle to swap in LSx and its computer, etc. into an LTx late model c4 corvette (swap may be more difficult there) ?

Thats what Im trying to figure out.

CALL911

I think both are similar as far as power making ability goes. You can attain essentially very close power levels FI with LTX and LSX. For example, you can easily attain 850+ RWHP even with an LTX with say an F1R, a fully ported set of AFR 227's, a sheet metal intake, and a FAST XFI setup (and all the other supporting mods). That same power level can be attained with a similar LSX setup. So in the reguards of power making ability, "Yes" they are similar.

This is where they differ. Price. It's not a HUGE difference, but there is a distinct difference in the parts needed to make the LTX that powerfull compared to the LSX parts. There just are more venders, more parts, and tuning is done much easier on the LSX platform for them to be similar on the price side of things.

Can they be equally as powerfull? My FI LTX has proven that time and time again. But to be equal in effort time and cost? I don't believe it to be so.

97FormulaWS-6

Right there is your answer.

Bottom line is this... To build a Boosted LTx motor to perform as a similar LSx motor you are going to spend a fairly decent amount more $$. Anything can be done if you have enough $$. It all depends on your goals and budget. You will get more power/performance/reliability out of a LS based engine for the same cost.

dizwiz24

What is a sheet metal intake? Does this have the intake opening on top vs. On the front?

97FormulaWS-6

A sheet metal intake is one that is made from pieces of sheetmetal welded together instead of a cast aluminum ones like stock and the Edelbrock aftermarket ones for LTx motors.

This is a Hogan made sheetmetal intake:

dizwiz24

Thats a good picture. thank you.

what are the advantages of this? do you need a high rise hood? what rpm-range does this thing come to its peak at.

I noticed this car (which is based off a SBC and made I think close to 1200 rwhp) also has that kind of intake..

http://roguevette.com/KV/index.htm

97FormulaWS-6

The advantages are they are custom built to the application, they can design and make the intake match the motor it's going on to. There are lots of effects the volume and shape of the inside of a manifold have to the performance of a motor. These are purpose built for exact motors; not mass-produced in any way.

The hood clearance depends on the design, the RPMs also are a function of the design. These are all things that get discussed when one has one of these built. They are also a lot of $$, and unless you're building a monster motor where you want every last bit of power possible or just have $$ to burn they are not typically used for our cars. The LTx intake manifold is a very good design for what it is, that is why there is only Edelbrock making an aftermarket one, and theirs took almost 10 years to come out.

CALL911

The sheet metal intakes are quite pricey, however if you are running a D1 equivilant or larger blower, or a 67mm or larger Turbo, the sheet metal intakes can easily net you an additional 60+ RWHP over the factory style intakes. These are FAR superior to the LTX intakes. I would not say the LTX intakes are "very good". Especially when needing more air in an FI build like we are talking about.

lymlyt96

Ok so I have a good question. Are sheet metal intakes like the Hogan one pictured above superior to a cast aluminum vic jr intake? If so, by how much?

CALL911

To my knowledge, one is not SUPERIOR to the other.

97WS6SCharged

It really depends on the whole combo. The great thing about a sheet metal intake is you can tailor it to complement the rest of the engine where a cast intake such as the Vic Jr. is made to suit a wide variety of engines and may not be the perfect intake for your particular setup. Then again, you can get an entire Vic Jr. intake with rails for less than $500 where the sheet metal intake will run you 5x that.

Fastbird93

I think the comparisons go through the FI setups too. Mod for mod, the boosted LSx will outdo the boosted LTx. As Call 911 said, you can get a boosted LTx to 850 with an F1 blower, sheet metal manifold, AFR 227 heads, etc, on about 18-20 PSI. But, look at it from the LSx point of view. Let's say you do a LS3 short block which is about 376 CID.....so you give up a few inches displacement, and some stroke length. But you have FAR better heads, and using a stock LS2 or LS6 manifold, you'll make easily the same power at that boost level with a more tame cam and less money invested.

If you put part for part, meaning sheet metal manifold on both, etc.....the LSx will still proportionally pull ahead of the LTx.