Kemp3

So I have read about every thread here on the LS4 and any power adder option. Maybe you can help me understand why this engine is so under powered. Its 5.3l and 300 hp while a 5.7l engine can put out 400+ hp , so taking into consideration the displacement seems there is still alot of power missing. With all that said , if you started with a bare LS4 block and build up from there can this engine hit LS1 numbers ? or is there something greater than that limiting it ? I know its been covered and quite a bit of cams and what not have been tried . Is there another option ? tearing down a LS4 and starting from the bottom up ?

I hope i am not beating a dead horse ..... sorry if I am

-Kemp

TheMonteMan

the intake manifold and exhaust setup hold the motor back. i doubt it would make the 300hp if it didnt have the ls6 heads on it. im sure power was kept to 300hp do to the weak kneed tranny, fuel economy, and the lack of need of a 300+hp fwd family sedan. i dont think gm threw too many 400+hp 5.7 in there family sedans. this is just speculation but im sure if the car had a ls6 intake and cam to match its heads it would produce far more power. other than intake manifold, cam, and header build. youre going to be lookin at n2o, or turbo setup, but then again not to many factory stock 350s are putting out 400hp. are you looking to build one for a swap or do you already own an ls4 car?

JP_GXP

Restrictive intake and exhaust manifolds kill our stock power, aside from that I think the DoD modifications kill a little power, too. Other than that I dunno, not an engine builder. :/

JDMC5

iTrader: (3)

themonteman got it pretty damn close. The intake manifold is the biggest restriction, the only plus side is the LS6 style heads, other than that everything else is lame compared to other LS engines. You have a tiny DOD cam, small MAF/ intake plumbing and very restrictive exhaust.

With the right combination 350 whp is obtainable, so yes they can exceed stock LS1 numbers.

Mels SS

iTrader: (1)

The heads flow very well the intake and the exhaust are the real issue and the stock tune.

Kemp3

well i am planning to run this engine on Megasquirt , so i will have complete control over the tuning . That aside i have read LS6 intake and TB is the way to go on intake , I will prolly have custom headers made so that eliminates the exhaust side . In almost every thread I read about cam swaps there was 2 end results. 1 - hp and tq numbers didn't really improve and 2 - stock cam was put back in . One thing I havent been able to get a clear answer on is the DOD lifters. If I dont use a LS4 valley cover and a LS2 cover ,eliminate the oil sensor ( or what ever it is ) for the DOD . Will the lifters be ok for the life of the engine ? or is it a must to remove DOD lifters if DOD is killed not shut down.

thanks again

-Kemp

LS1 Racing

iTrader: (15)

Better set aside about $3K for a built transmission.

Kemp3

Trans is taken care of , I dont want to go to far into details . I promise if I go this route there would be some videos of drive and dyno time. The valve train is a major concern to me , I really need to know what the issues are since I am not running a GM ECU. MS3 allows me to use SD so a restrictive MAF is eliminated . are the bottom ends on these engines strong enough for any kind of boost ? is there proven turbo setups on stock engines that have some miles on them ? Also since I am making custom headers would a LS1 header flange bolt straight up to the engine ?

I know tons of questions ... just havent been able to get all of these questions with clear answers .

thanks

neilownz

The bore size is smaller than other 5.3 and 5.7 engines gm uses.

They make a 300 hp v6 or a supercharged 3800 if you want that instead.

fieroguru

iTrader: (1)

As stated above multiple times, when you look at the LS4 specific components they are undersized vs. their LS(x) peers.

For a naturally aspirated build, I would suggest upgrading the MAF, TB, Intake, Camshaft, and Exhaust to see the full potential of this engine. I think they all need to be done to see large gains and so far very few people have done them all.

The other option is some sort of power adder and the turbo setups are gaining in popularity.

boeman

From what I can tell, the transmission in the LS4 cars has kept a whole lot of people from doing any huge power increase... the community has a lack of real world performance information because of this.

TheMonteMan

ls1 flange should work. there have been cam swaps done. i also believe there have been cam swaps recently that have been done with intake manifold swaps that produced good numbers. if you search youll find them. there have also been turbos done that doubled hp on factory bottom ends. off topic but theres a guy on my other forum that actually put a turbo ls7 in his car. the build is pure insanity.

BlauGXP

Let's also not forget that GM didn't really intend for the LS4 to make any more than what it does. At 323lbs-ft, they're already taxing the stock trans' of the vehicles that they were made for, so in essence the engine does exactly what it was designed for and does it very well IMO. These cars may be FWD, Automatic, and fairly heavy, but if you don't like it then buy a G8

GXP25

iTrader: (3)

The guy quoted above pretty much summed it up.

Here's some more information on where to start: http://www.fiero.nl/forum/Forum2/HTML/113207.html

Thanks fieroguru!

I'd go with a larger throttle body, LS1/LS2/LS6 intake manifold (and appropriate injectors), upgrade the MAF, aftermarket G8 DoD/AFM camshaft, headers, and finally a 3" exhaust (headers back).

Of course you would want to take care of the transmission as well.

AlabamaGuy

iTrader: (5)

Why megasquirt? The stock computer can be tuned to handle more power than a built trans can take. On the other issue, if all things are equal, the shrouded valves from the tiny bore are the root limiting factor.

JDMC5

iTrader: (3)

You can run SD with the stock computer you know. Yes, the bottom ends are VERY strong and stock, turbo cars easily trap 120+mph. Yes, the LS1 flange should bolt right up.

PM, NMP0098 your questions about the lifters, he knows the specifics.

Brian396

iTrader: (3)

I’m running 2 bar OS with a little help from HPtuners. The car loves it, and hell even my technically challenged *** can tune with it.

JDMC5

iTrader: (3)

can you post some acceleration videos?

Brian396

iTrader: (3)

Not till I get the tranny rebuilt. Hopefully I can limp it thru till April. Then its off to TEP.

JDMC5

iTrader: (3)

cool sounds good.