logikal6785

i was looking at go-auto-center bc i'm doing a frame-up next summer which includes a motor swap. i really like the idea of putting in an LT1 with LT4 components. the LT4 spec engine on this page is quoted at 425 hp .... how accurate / possible is that ? i understand it's @ the flywheel but still - ya ?


http://www.goautocenter.com/gen_ii_lt1.htm

Kory-88Iroc 350 tpi

iTrader: (1)

That is probably pretty close to accurate. I have a hot cam with home ported lt1 heads and headers ,ect . I figure I am making over 400 hp. I hope to dyno it soon. Most lt1s with bolt ons and hot cams run around 400 crank hp.
Keep in mind that that engine probably does not include any accessories, or a computer or harness.
Hope this helps.
Kory

logikal6785

thx 4 ur help man. how much would i expect to pay for a full wiring set and chip ? i'm going to bypass smog anyway so i don't plan to worry too much about the OBD system

TexasLT1

Id say 425 is right on the money. I did the LT4 heads, intake, and Hot Cam swap a while back, and damn what a difference it made over mostly stock. Once I get good exhaust, I expect to see a pretty good difference. I desktop dynoed it at about 430, dont know how accurate that is, but the butt dyno agrees! Once I get my car back at Christmas Im going to take it to Houston and get it dynoed just for ****s and grins. Hopefully I'll get exhaust too, dont know yet. but to answer your question, 425 is easily attainable.

Markolc

What I would do is find a nice longblock complete with PCM and 4th gen accessories to start. That's around $2000 after shipping. Then you take the stock heads and have them ported....you don't need a full port job but you can easily clean up LT1 heads to outflow stock LT4 heads for about $450. Then you can get your hot cam kit for around $500 and you'll be making near 330-350 HP at the wheels! (430 or so crank HP). It seems it'd be a cheaper way than the LT4 route. You don't need the LT4 internals to make for a strong motor, a stock LT1 block along with a production LT4 timing chain is all you really need to support the HP beautifully. You'd want to save your money for the physical stuff itself because you will have to fab and create things to make the swap perfect. :-)

logikal6785

that's a good point, but i like the peace of mind offered by a 3 year warranty on the engine and the guaranteed functionality of an out-of-the-box DFI harness so i don't have to worry about old, corroded wires giving out and me having some mystery problem kill my car. anything added to this motor would be in the form of NOS or a SC, since it's already fairly high tuned, so i'd be just about done with the internals.

Markolc

An LT4 motor will still take a safe max of a 150 shot of juice, just like a regular LT1 and your standard 6-9 PSI of boost from a SC.

BTW, just a heads up for you, there's no LT1 SC kit that will fit an LT1 in a thirdgen engine bay, unless you fabricate a bracket and pulley system yourself. Me and my friend have been looking long and hard at it with our LT1's. Just look at where a SC mounts on a 4th gen and you can see that the SC would hit the Steering box/frame in the thirdgen engine bay.

logikal6785

that makes me sad i really wanted to run a SC =/

would you say the best thing to do for now would be to max out the N/A performace possible by getting the LT4 and running some NOS and all the mods i can to exhaust intake drivetrain etc. until i can figure out a way to fab up a SC bracketing ?

btw thx for the info mark you've saved my sanity with the bracketing info

Markolc

If you don't have emmissions, you can get absolutely sick power NA out of an LT1 and still spray juice on top of it...I'm talking like breaking high 10's with a 150 shot! But you wont do it with stock casting LT4 heads...you'll need to port them, or better yet, fully port LT1 heads and get a cam similar to what I currently run. Combine that with a 150 shot and you'll have more power than you can handle on the street....Close to 400 RWHP on the street NA.

Markolc

Woops, just saw you're in CA. No biggie, you will still want the highest flowing heads available (this is a must for NA, juice, or blown applications) and a good cam like a CC305 that will still pass an emmissions dyno test. That's good for about 370 RWHP.

Another thing to remember, DFI is illegal in CA....It no longer controls your emmissions equipment...You may have to use a 4th gen PCM.

logikal6785

omg no way ! funk the CA emissions tests i have ways around them =D

and dfi is illegal ? well, in for a penny in for a pound

logikal6785

how much is it going to be, roughly, to get a full port & polish job on a set of LTx heads ? and would port & polish on LT4's flow any more than a set of port & polish LT1 heads ?

i'm wondering now whether i should get the LT1 or LT4 =/ either way yes i'll def be running a massive cam and a healthy shot of juice ... i'm just stuck wondering exactly what to put into this land rocket

Markolc

LT4 heads have the potential to flow better than LT1 heads, but that always depends on the guy doing the porting. A full port and polish job always looks to be around 1200 bucks, and of course, it depends on the shop. The best deals that I've found were going to the CZ28.com For Sale forum and looking for someone selling Stage II heads. Stage I heads generally flow in the 240-250 CFM range on the intake at .550" (a little better than stock LT4), Stage II heads generally flow in the 270-285 CFM range. Look at Stage II heads for sale in the $1000-$1200 range and you'll be making out like a bandit. Stock LT4 heads sell generally in the $1000 range, so you'd be saving money and getting a LOT of power for the buck.

As far as wiring the motor, I really do highly recommend getting a stock OBDI PCM and purchasing an aftermarket wiring harness. For best results, contact someone to get you a harness that's customized just for you (should be about the same or very close to the price of a Painless wiring harness or similar). That way you'll be emmissions legal. Who knows if in 3 years your emmissions contact is no longer there and you have to legally find a way to pass (uh oh).

logikal6785

true, and good advice, but i don't want to have another dumb thing that could break on me ( OBD system ). there's always a way, and when college is over i'm moving to oregon so i'll be ok on the emissions. i'm looking for simplicity and power ... maybe i should just fill a bucket with gas and ride that though :sillylol:

would the machinist charge much more to get the heads ported and polished if i had already driven with the heads on the block than if it were out of the crate?

Markolc

Usually they won't charge more, cuz it doesn't really make a difference.

logikal6785

well at least i won't have to spend an extra million dollars on that