dude I just finished with the complete lt4 conversion on my ta.This kit is awsome.I don't care what anybody says.I even used the WEAK lt4 springs.If your looking for a fun streetable car this is the kit.Get it tuned by pcmforless awsome hotcam tune.

 

One reason for the "LT4 Conversion" kit making more HP than a stock LT4 is the fact that the LT4 Conversion kit includes the LT4 HOT cam, and the stock LT4 has a cam that really no different than a stock LT1, just comes with 1.6 RR's.

But that does not account for all the extra 95HP. MORE Motorsports tested a bare LT4 conversion on an engine dyno - no accessories, nothing. Just a bare engine. That produces SAE "Gross" HP ratings, not the SAE "Net" HP ratings used by the factory, and reflects a complete engine with all the accessories and full intake and exhaust, as actually installed in the vehicle. MORE also used a long list of additional parts that are not in the LT4 conversion kit (and many were not mentioned in the magazine article that documented the testing), and topped it off with a $3,000+ aftermarket ECU. The 425HP number is totally meaningless.

 

I think there's an up side to doing the LT4 conversion. We all know you can get more bang for your buck by porting your LT1 heads and carefully choosing other parts, but the LT4 kit keeps your car all GM and if you ever had to buy a car from someone, which would you rather have? A bolt-on car with all GM stuff? Or some heads ported by joe blow and other aftermarket parts? Even if the car is faster and you had confidence in the work that was done, there's something to be said for keeping your car built with parts from the catalog. Now if you've already got a ton of other aftermarket stuff done to it and it's already pretty much molested, or you really want to go fast and aren't going to sell it, then it probably wouldn't have any real benefit for you to do it that way.

 

I think its sort of ridiculous to treat anyone who happens to want the LT4 parts as "ignorant".... and that unfortunately is the message that is being posted by some. As long as you know the facts, BUY WHAT YOU WANT! When I bought the LT4 parts in 1999, they were the best available, proven by head flow tests by the shop that built my engine. They had a huge catalog of known LT1 and LT4 heads that they had flowed - same bench, same conditions, same operator, and at that time, the best flowing LT1's were the Gallant (GTP?) heads. And the LPE and CNC LT4's were better than those. The Canfields were good, and the AFR's were dogs. Is the same true today - NO. But I'm still happy with what I have... even if its just because of the shiny red intake manifold.

Its your car.... do what you want with it. Don't let the people who heap ridicule on your decision deter you from your choice, as long as you did your homework, and know the facts about what you are buying. Its very fashionable and cool to badmouth the LT4 stuff.... and its unfortunate the GM did not complete the LT4 development program, having run out of money. They ended up with a compromised design.... but it isn't "junk" by any means.

 

To get some more power and use the Lt4 springs a little buy some Scorpion 1.7 rockers ($220 in either 3/8 or 7/16 from Flatlanderracing.com) . That combo will put the higher flowing heads to use and get some good hp even without the cam. If you hot cam it too you'll need better springs but that's later.

Maybe for now go with some thick head gaskets to drop the compression so you can put a low boost blower on (much more power and drivability than a cam anyway).

Hal

 

If you want the LT4 stuff just to keep a car "all GM" that is fine, but don't pretend it is an awesome package because the facts just do not support that.

You are happy because you don't know any better.
Proven that for similar money you can make as much power at the tire through a M6 as that kit does at the crank.

If you are in WI or norther IL I will meet you at GLD or WIR to show you.

The fact you are happy with that tuning just further supports the fact you don't know any better.

I was the same way at one point, I have learned a LOT since.

You seem to have comprehension issues as well seeing as it has been stated repeatedly that the LT4 springs are weak when used with the HEAVIER LT1 valves and that springs break in and lose some pressure. So happy days after completion means nothing about the long term appropriatness of a spring for an application. Since you have light LT4 valves though the springs will work better than they would with LT1 valves.

 

If I was to buy a modded car, I would need to have some confidence that the mods were performed by somebody who had a clue. A "bolt-on car with all GM stuff" would be an indicator of the opposite. LT4 heads in most cases would also be an indicator of the opposite.

 

Why in most of the lt4 post's you answer to, and there's alot you always say pepole are ignorant or don't know any better about going with lt4 equipment.
Give it a break.Now your puting down pcmforless there's many guys and girls using it on this board.all i hear is good things about bryan.

 

Popularity means NOTHING about whether something is good. Just means it is cheap with a good marketing strategy.

I will present my argument, please argue it based on data. Feel free to correct me if you feel any of these statements are inaccurate.

On the LT4 I think we will all agree the highest number we have seen for a flywheel number is the 425hp published some time ago by a magazine using a fancy aftermarket injection system.

I think we will all also agree that 400rwhp is attainable with ported LT1 heads.

What is the average LT4 conversion RWHP? Maybe 330?

Like I said please keep arguments to those points.

How can any you draw any conclusion but that the LT4 kit underperforms for the money?

Like I said keeping the car all GM is a seperate thing, that is fine, lots of guys like to mod old musclecars with just factory options, I can appreciate that.

 

To me it's an awesome package period.STOP CALLING ANYONE WHO CHOOSES LT4 EQUIPMENT IGNORANT.

 

Again I ask that you keep the argument to the facts stated.

The LT4 package makes in an absolutely perfect world 425fwhp. Maybe 330rwhp average.

Ported LT1 heads and complimentary cam can pretty reliably make 400rwhp and in some cases a good bit more.

Anything wrong with those statements??

 

The problem with getting heads ported is it's almost as easy to do a bad job. The average person takes it to a shop, sure they'll port them. But, they'll probably take too much out and kill the velocity or go through to a water jacket then have to weld it up and charge more. And all the while your car is down. Nobody here would want to buy heads with unknown flown numbers after some average shop did them. LT4 certainly isn't the best but it is a sure thing. And a great lt1 port with good valves is not cheap. You can sell off you lt1 heads and put that against the LT4 ones so the car is only down for a weekend. If you not going for a huge cam than LT4s will flow good enough. Now there are better cams then the HOT to go with these days but they require expensive springs as well. You say the LT4 kit has only 330 rwhp but that's as much or more than a lot of old muscle cars that are legends.

Hal

 

There are plenty of places well known to do decent to great LT1 head work, no need to take chances on someone unknown.

Agreed?

Far as buying heads for no downtime, you either buy a used set of cores or some shops offer a core charge that is refunded when you send in you old heads in good shape.

Agreed?

330rwhp is better than a lot of old musclecars, but my argument is that for similar cash you could have had an extra 70rwhp.

Is that argument in any way invalid?


Cut the emotions out and look at it from this perspective.

 

Are they as well known as just buying LT4 heads? No. The average person or even shop won't have this info.

So just for the sake of argument, show me a place where you can get heads for about $1300 with valves and springs that flow far better than LT4 and go with your favorite 503 cam and 1.6 rockers? I mean that's the argument, right? A set up for the same money that gets even close to 400 rwhp.

Cut out the emotions? What in the world did I say?

Hal

 

If this were stricktly a horsepower per dollar arguement, no one would be running anything ltx. We would have all moved on to lsx. This is always the argument you present 96capricemgr, so why are you wasting money foolishly on anything ltx and not running lsx or genI for that matter? Does your choice to run ltx make you ignorant? NO, and neither does anyone's choice to run LT4, yet you never pass up a chance to trash anyone's lt4 choice.