LT4 kits... Yes, or No!

[xxRillixx]

http://store.summitracing.com/partde...=NAL-GMP3287-1

I see kits like this one for sale... they say," 425+ Proven hp" after install of this part ALONE. It looks basically like an engine rebuild kit, but are they any good? Does anyone have experience with an LT4 kit, good or bad?

-When should an engine be rebuilt? I have a 93 350 Lt1, but it only has 54k miles on it... is this kit worth my time?

Thanks!

[Mike71]

$2k...passes out

[Fastbird93]

Just my opinion, but it's really not worth it. For about the same price as that kit you can have a custom cam, your stock castings ported, and very nearly the rest of the stuff, and have 425 at the wheels, not the flywheel.

[N20LT4Bird]

It depends on where youre going with it. First the LT1 manifold doesnt allow for much port work, the LT4 does. The LT4 heads and manifold when ported will outflow the ported LT1 heads and manifold. The LT1 heads are only gonna get you so far, then you'll have to go to another casting like the LT4. The LT4 castings provide for a lot more than 425 horse when they are ported. Most of the "Big Dogs" run an LT4 setup or equivalent. Theres a reason for it....

However, be aware that the 425 horse that is advertised is after custom PCM tuning and a few other bolt ons like headers and throttle body, so be prepared for that is you decide to go this route.

[DJ Taso]

And just saying you have the LT4 alone makes everyone's jaws drop!

[xxRillixx]

LT4

Thanks!! Is there a certian company that makes the best kits? Or is it more beneficial to just get the parts seperately? My uncle is a mechanic, so parts are less expensive and i have someone to help/teach me... not that trial and error isnt fun!

[Kevin - Blown 95 TA]

The LT4 kits you are seeing are GM. Just shop around for the best price and verify that you are getting all the parts that are included with the kit. They give you most of what you need to do the job. It is a nice kit, even tho you don't generally get all the hp that it says w/o some other parts. If you can do a rear gear and a cold air intake along with an exhaust, your car will be a different character

[Al 96 Ram Air T/A]

OK...here's the truth.

The first thing people will claim who have really no idea about what it costs is that for less money, you can port the stock heads and out flow the LT4 for less money...no, you can't.

I've researched this every which way for three years. They are wrong. LT1 port jobs cost about $1500. For that, you get good flow numbers and larger valves. You still need roller rockers ($150 - $300), a cam ($200), and a gasket set ($200). So for a grand total of $2000+, you get heads that may slightly out flow the LT4 set up.

Now, look at the LT4 package. GMPP pricing...
LT4 kit runs about $2000. Now for the part everyone forgets....you can sell your used parts! Used LT1 heads run about $300, intake about $150, cam about $25. The LT4 kit comes with the $300 roller rocker, the $200 cam, and the $200 gasket set. So, for a grand total of approx. $1500, you can have nearly the same power increase as the LT1 set-up, but with the advantage of further power potential from the LT4 heads.

It drives me crazy when guys claim you can get ported LT1 heads that flow better than LT4 heads out of the box for less than $1000. NO...you cannot. Find them for me...I'll buy them. Good LT1 heads (Lingenfelter, AFR, GTP, etc. ) costs in excess of $2000 - $2500, and that does not (usually) include keeping your used heads or getting the Crane Gold Race roller rockers.

While I will submit a top notch port/polish job on LT1 castings will out perform LT4 castings (stock), it costs big bucks to accomplish this. And after you perform the so-called Stage 3 job on the LT1 heads, your done. However, the LT4 castings have lots of power still in them. Just ask Fred how much potential. He's making nearly 500 hp on a 383 LT1 (NA) and ported LT4 package. Approx. 650 hp on giggle gas. Try doing that with "Stage 3, 4, or 37 for that matter" LT1 heads...not gonna happen.

So , in a nutshell, misinformation is flyin' all the time. Calculate the numbers for yourself. The LT4 package has been tried, tested, and tweaked. It is a pretty darn good starting point for future mods. Stroker, turbo, nitrous, or supercharger...the LT4 can be ported to handle that and more. Rebuild the engine, stroke it, sc' it, whatever, the LT4 heads will not be the weakest link. However, the LT1 heads will be. And, it's cheaper in the long run...

[Z Ya Later]

From what I've read, researched and seen, if you want power the LT4 kit is a good way to go. If you're gonna rebuild the motor, just buy the LT4 kit along with a 383 stroker kit and you'll have almost all the parts you'll need right there, minus the small things like freeze plugs, bearings, etc. I'm not sure on the cam though, as I don't think the LT4 hot cam will go well with the stroker kit. Feel free to correct me if I'm wrong anyone, because this may be where I take the Z and the more I know now the better.

[Formulaboy95]

I was thinking of picking up the kit from Jason Cromer for $489, along with the HD Timing chain, and a tune from PCMforless. Then do the LT4 Heads and Intake later. Easier on my pocket, to do it in steps. Still researching all the other parts/tools I will need. I Should have done the timing chain cover gasket when I replaced the opti....

Sam Taylor LT4 HotCam Kit

Anybody know what the typical gains would be for this type of setup? HP/1320
I noticed that when my car shifts at approx 70mph, it just doesn't want to pull like in the lower rpms. yep, standing on the pedal before the 1/8th, time to satisfy my craving for speed.

[Fastbird93]

Unported LT4 heads flow what? Maybe 245 out of the box?? For a marginally more cost amount, you can have you LT1 heads ported for $1500 and be flowing in the area of 270-280 at peak lift (.550 give or take) with much more low lift flow than the LT4 also. Couple that with the LT-4 Hotcam kit, and you're still looking at more power than the $2200 LT4 conversion kit.

If you want that LT4 kit to perform better than a set of ported Lt1 heads, you better add the cost of porting to that then.

Best deal going for LT1 heads right now is Lloyd Elliot. He's getting consistent flow numbers that are performing, complete for $1300 or thereabouts. I don't remember making a claim of $1000 for porting. If you know where to find that deal let me know.

Oh, and good luck selling Lt1 heads for $300 and an intake for $150.

[N20LT4Bird]

Im gonna go ahead and agree with what I said before and what Al said again (in a longer version). YES! You can get LT1 heads to outflow box stock LT4 heads, but most people plan for the future when they mod - everyone knows the disease. "Hi, Im Sean and im a go-fast-aholic" So, its really smarter to save your 1300 in LT1 port jobs and put it towards a good set of heads. The LT4 heads flow real nice stock and provide room to grow when you get bored in a month. The LT1 port job for 1300 is just about the end of the road. Are you gonna put down some power - YES! Is it going to compete with the LT4 set up? Thats debatable. You gotta remember that the kit for 2000 is more than heads and a manifold. Its the roller rockers and cam too. So, you gotta add that to the price of your 1300 LT1 port job. I wouldnt waste my time and money. For a just a little more, you can do the job the smarter way.....

[fastTa]

Originally posted by Al 96 Ram Air T/A
OK...here's the truth.

The first thing people will claim who have really no idea about what it costs is that for less money, you can port the stock heads and out flow the LT4 for less money...no, you can't.

I've researched this every which way for three years. They are wrong. LT1 port jobs cost about $1500. For that, you get good flow numbers and larger valves. You still need roller rockers ($150 - $300), a cam ($200), and a gasket set ($200). So for a grand total of $2000+, you get heads that may slightly out flow the LT4 set up.

Now, look at the LT4 package. GMPP pricing...
LT4 kit runs about $2000. Now for the part everyone forgets....you can sell your used parts! Used LT1 heads run about $300, intake about $150, cam about $25. The LT4 kit comes with the $300 roller rocker, the $200 cam, and the $200 gasket set. So, for a grand total of approx. $1500, you can have nearly the same power increase as the LT1 set-up, but with the advantage of further power potential from the LT4 heads.

It drives me crazy when guys claim you can get ported LT1 heads that flow better than LT4 heads out of the box for less than $1000. NO...you cannot. Find them for me...I'll buy them. Good LT1 heads (Lingenfelter, AFR, GTP, etc. ) costs in excess of $2000 - $2500, and that does not (usually) include keeping your used heads or getting the Crane Gold Race roller rockers.

While I will submit a top notch port/polish job on LT1 castings will out perform LT4 castings (stock), it costs big bucks to accomplish this. And after you perform the so-called Stage 3 job on the LT1 heads, your done. However, the LT4 castings have lots of power still in them. Just ask Fred how much potential. He's making nearly 500 hp on a 383 LT1 (NA) and ported LT4 package. Approx. 650 hp on giggle gas. Try doing that with "Stage 3, 4, or 37 for that matter" LT1 heads...not gonna happen.

So , in a nutshell, misinformation is flyin' all the time. Calculate the numbers for yourself. The LT4 package has been tried, tested, and tweaked. It is a pretty darn good starting point for future mods. Stroker, turbo, nitrous, or supercharger...the LT4 can be ported to handle that and more. Rebuild the engine, stroke it, sc' it, whatever, the LT4 heads will not be the weakest link. However, the LT1 heads will be. And, it's cheaper in the long run...

No offense but just about everything you said in this post is far from the truth.

I have been witness to several flow charts on stock/unported LT4 castings and the best peak I have ever seen is about 250 @ .500" of lift. While this isn't too shabby, a mild Stage 1 port on a LT1 casting can easily, easily outflow this.

And LT4 castings are not a good choice at all if you plan on going with a Stage 1.5 or further port work and running boost. Due to the port shape and design of the LT4 intake runner, the intake runner "floor" port wall thickness is very minimal making them very weak, especially under boost.

"And after you perform the so-called Stage 3 job on the LT1 heads, your done."???? Not even close my friend! Trust me. There is plenty more port work and combustion chamber work that can be done after the Stage 3.

I know of several people (Joe O being one of them) that are making in excess of 800 flywheel hp through LT1 castings naturally aspirated! 500 hp is nowhere near the limit of LT1 heads!

No offense but it would greatly benefit you to get accurate info on cylinder head performance. Sounds like you need it.

Are you talking about just the port work for $1000 or a fully assembled head for $1000?


*EDIT* Let me just make sure I clarify something. I am by no means knocking the LT4 heads. I am currently using these myself. I just wanted to show that the LT1 is not too far behind.

[xxRillixx]

hummm, im still confused... but im looking for the long run, so i think ill stick w/ the Lt4.

[Fastbird93]

Originally posted by N20LT4Bird "Hi, Im Sean and im a go-fast-aholic"

First, it's very weird that you said that because Sean is my name.

Ok, I'll admit, the LT4 does outflow the LT1 heads when the same ported hits them. Up Top. The rest of the numbers are comparable.

My personal philosophy is that for the price of the LT4 kit, you could instead pick up some AFR's and really go the big route. The LT1 head (as well as the LT4) makes a great starting point when ported. But for the money, I'd rather go with a little more expense up front.

Personally, the LT1 and LT4 heads are so close in comparison that I just don't feel it's worth the time. Granted everyone plans for the future, and once you do the heads, there's always more that can be done, but really?? How many people actually pull and have their heads worked on multiple times for touch up inbetween setups. Only the really hard core guys, the "competitive" guys if you see what I'm saying. Most people want it done once and back to running. If you can't afford to port the LT4 heads, then don't get them and have yours done. Heck, even pick up a set of LT1 castings on Ebay or a board for $200-250 and don't waste any downtime on the car.

I'm standing firm in the fact that you can have a much more powerful car for very close to the same cost as that LT4 conversion.