Since I've spun a rod bearing, I've been searching forums and Craigslist, local and abroad. I have found a complete engine around my location with lt4 intake, and heads. I can hear it run right now. I'm thinking with the stock short block, cc 306, headers and 3" true duals, and a 3.73 gear. Will that be a decent combination and put atleast 325 rwhp. Also, what, if any are visual ways to tell lt4 stuff apart from lt1? I know the intake is red but any idiot can paint an intake red, and sell it to another idiot, like myself, and call it lt4. I've heard there's a little more material on the intake to help seat better on the heads, but don't know anything else.

 

Search this forum and find the LT4 casting numbers. Then pull the valve cover off [easy to do] on each side and check the casting numbers. It's an easy way to see if they really are LT4 or just factory LT1 stuff. Intake casting number is found on flange where it bolts to the head, also pretty easy to find. That'll help you figure out what you've got in front of you.

A CC306 and LT4 heads/intake should make 375rwhp+ easily in a 6 speed car with a factory rear end. With 3.73's, 6 speed and a good tune it'd be a fun car to drive. Probably going to need bigger injectors too, remember to get them before you buy a tune for the car.

-Dustin-

 

LT4 part #'s:

LT1 vs LT4

 

As always, Injuneer, you come through with excellent info.

Bersaglieri, I'm sorry, forgot about injectors. I honestly thought the lt4 ones would hold up, but I assume 32's would be proficient enough to run unless I put a bottle on it, but I doubt that'll happen. All I know is I hope this engine doesn't sell for a couple weeks so my money is right.

So with a couple of bolt ons and this setup, I could possibly be close to 400rwhp? Thats a lot more than I was expecting. I appreciate the info

 

He said 375 - not 400. If you see 375whp I'd be impressed, but 400whp is out of reach with that combo, IMO.

 

375 is close to 400. Lol, its a lot closer than 275!! If I get 325, ill be so damn excited I'd probably kiss the tuner!! Seriously, I'm just wanting opinions. I did not mention, cause I didn't know, but the heads and intake are supposedly ported, and shaved. And after what little research I've done the cam will be on the small side. Was thinking maybe a 280 or 292, but I'm almost positive the 292 is out of stock short block realm. I've heard of people spinning 7500 and still pulling on a dyno. So if the heads and intake are what he says they are, then I don't think 400 is out of question. Or am I getting too excited? He had a pcmforless tune, I will actually have it dyno tuned when I get there. Also, would 42lb injectors be overkill and hurt anything, I've found a good deal on a set.

 

You're getting too excited. Seen it a thousand times over the past 13 years working with these cars. The cam can probably get you close, but stock LT4 heads aren't going to cut it. You say they are ported but to the extent (and quality) are unknown. Unfortunately many supposed "port jobs" are little more than some gasket matching "horrible idea" and an overelaborate valve job which can actually make the head perform worse so let's just assume the heads are as-cast LT4s.

You can't spin past ~7100 on the dyno with a stock LT1 PCM - the PCM's tables don't extend beyond that.

I'll assume the "292" you mention is the Comp XFI 292, which is FAR too big for stock displacement. That's bigger than the camshaft I have in my 383. The XFI 280 is a better choice, but IMO there are FAR better grinds available. Nowadays getting a custom grind or off-the-shelf grind from AI or LE would be your best bet. The XFI stuff was nice years ago but nowadays there are grinds that aren't based on SBC ideology 20 years ago. Custom grinds may be more expensive but they're certainly worth it, IMO.

Better to wait and do it right once then hurry and do it wrong twice.