After years of being an LS1 guy, I finally had to get rid of my 99 1LE Z28 in lieu of a more family oriented vehicle because my wife and I just had our first baby. On the flip side I recently acquired the 97 30th anniversary edition Z28 that my dad initially bought for me in '97 in hopes that it would inspire me to do well in school. Well that plan didn't quite work out, so we made some alternate arangements about a week ago, and I got it for a great price.

I've got a lot of learning to do about my LT1s so I'll start off with some questions that ya'll have probably heard a million times:

First, I noticed while I had my LS1 that the cam choice I made for a mild runner had final specs of 221/221 .558/.558 112, which from when I look around has more lift than just about anything I've seen for the LT1's. I know this is due mostly to the fact that the LTs are running 1.5:1 rockers as opposed to the 1.7:1s in the LS, so I was curious if any company made 1.7:1 ratio rockers for the LT1s or if stock rockers out of an LS1 would fit our valvetrain. Also how well do these cars react to the higher lift numbers, and how much p to v clearance do we have with that kind of ratio.

Second, The LS1's were the most mod happy cars I have ever seen and I was pushing 355 to the wheels and running 12.4 @ 114 with just a lid, cut-out and the "baby cam" you see listed above. How would you say the LT1's mod hapiness compares to the LS1s (just so I can get an Idea of what I've got to work with)?

Third, I was wondering what options we had for good intake setups. I know first of all a cai would be ideal, but from there what else would make a good impact on performance? I don't know if I'd play around with the MAF again because I had some issues with the one in my 99, but what are your thoughts? Next, is putting a resonator delete plug or a 1LE elbow on the car going to make any real difference? Also, I know I want to get an air foil for the TB, but what's an appropriate time to go with a bigger TB? Finally is the LT4 intake the only upgrade for us in terms of manifolds, and is there anything that has to be done to make one work besides just slapping one on? Also what kind of gains are we looking at with the LT4 intake over the LT1 intake?

Well I guess this is a start, but I'll be asking more quesitons in the future, you can count on it (I just don't want to bore you to death right off the bat with too long of a thread). Thanks in advance for your responses and for helping me get started.

Ryan B

 

A "big" cam for an lt1 is going to be between .575 and .610 valve lift. .525-575 is mild-moderate.

A CAI will be fine for the near future.
Leave the stock MAF alone.
1LE elbow is useful, but only to eliminate clutter IMO. No power gain there.
Airfoil is also useful, but gains are small. At 400 rwhp I believe a bigger TB becomes beneficial.

PTV clearance? I'm not sure of the set numbers there, but there's a good bit, a GM847 cam will fit stock heads and clear the pistons, 234/242 .575/595 112

The LT4 intake doesnt sit well on LT1 heads without machining, and there is no benefit there because the difference is the height of the ports, and without lt4 heads, there's nothing extra you can gasket match and get a gain with. There are no "magic" intakes for the lt1 that are mass produced. You have stock, ported stock, ported/welded stock, and sheet metal.

Edit: With a big cam (around the GM847 i listed above, there are a lot of similar cams out there, and custom cams), a manual car will push 345-360rwhp and 320-330tq or so in an lt1 with stock heads.

 

That's something I'm not use to seeing. That's a helluva lot of duration for not having to fly-cut the pistons. Are those specs on 1.5:1 rockers?

 

i think spinner pretty much covered it.

any CAI will benefit the car, leave the maf alone, do an airfoil if you can find one cheap, don't worry bout the tb till you're 400hp+ or have ALOT of spare money sitting around. the LT4 intake only goes on the lt4 heads.

there is a company selling 1.7rockers for the LT1 now...not sure of the brand. but standard 1.6ratio work well with most cams and are dyno proven 15hp to the wheels in conjunction with an lt4 knock module.

electric water pumps are also a worthwhile mod for some power

 

Those are on 1.6:1 rockers. 1.7 and higher isnt any good on an LT1 imo, because the lifters dont sit in their own retaining tray, and the increased ratio is only going to put more stress on valve springs, etc.

 

So would it just be better to get the LT1 intake ported then? Who does good port work, how much does it cost, and what kind of gains can be had?

When I go with heads, would I be better off going with a ported LT1 or LT4 intake manifold?

Thanks again.

 

I'm definately wanting a meziere, and the price seems to be much better for the LT1 than it does for the LS1. How about a set of pulleys also? What kind of gains might I see with pulley's and an electric water pump? 10? 15? 20?

 

Are those figures on a full bolt on car?

 

Don't port the intake. The stock intake is good for a nice bit of HP. Electric WP may free up to 10-15 horses. I have heard only bad news about the pulleys.

 

pulleys won't add any noticable hp, but they do reduce the parasitic loss to some degree. for an inexpensive mod i say it's not a bad idea.
dyno results

there is almost nothing to be gained from porting the LT1 intake...not really worth the hassle or money. the only way to run an lt4 intake is to run LT4 heads...the ports are in different locations and i think there is a differnce in angle of the mounting surface.

i've never really seen more than 10hp from the electric pumps. i suppose if you spun the car really high you may see more. but normal applications i think 10 is reasonable. the reason the LT1 wp is cheaper is because it is just the pump, not the housing. you remove the old impeller out of the stock housing and mount the electric unit in it's place. do a search there are install instructions floating around.

 

some more dyno results for you:

electric wp
throttle body bypass
airfoil
1le aluminumn driveshaft

 

Porting the intake by itself isnt worth anything, but is good for 10hp+ matched to ported heads

 

I personally wouldn't go with 1.7 rockers for an LT1. This is one of the things I don't really like about LS1's, (the other is piston slap but that's beside the point). The only reason they're prone to bending pushrods more than LT1's is the extra sideloads the longer rocker arms have. I know guideplates can take care of this, but I'd rather go with a cam that has good lift instead of trying to make alot of lift with longer rocker arms. That said I'd never go with anything larger than 1.52 Pro-Mags with a cam like the 847, CC306, or any of the XE line that are comparable in size. You don't really need the extra lift unless you go with aftermarket heads, but people have used 1.6's with these big cams without touching the stock pistons, but there is very little piston to valve clearance left.

Jason