Catmaigne

iTrader: (6)

I'm running out of ideas. The car is a 96 Z28 M6 with Pacesetter LT's, Magnaflow catback, Moroso CAI, and throttle body bypass. I'm trying to squeeze as much power out of my LT1 before taking things to the next level. I'm guessing the car currently has around 290~ at the wheels judging by #'s from comparable 6-speed cars. I know there are dinky little mods like airfoils and elbows that are worth 1-2 horses here and there, but I'd rather get down to business and tackle something a bit greater: the valvetrain.

I'd like to upgrade to 1.6 rockers and stiffer springs w/ stock cam and heads, but I'm unsure what gains I'll see. I've read everything from zip to 15-20hp so THROW ME SOME NUMBERS!

HP/TQ
Bolt-on or minor mods (preferably w/ rockers and springs)
A4 or M6
Dyno type

Before you flame all over my thread, consider this: I'm holding out on camming my car until I have the funds for some LE2 porting. The rockers and springs seem to be the next step and are relatively inexpensive. Plus, I'll be able to reuse the 1.6's when it's time for the overhaul.

But Catmaigne, why don't you get a tune and some gears instead?!
Way ahead of you... I'm swapping in 4.10's soon and will get a tune after the rockers/springs (if they're worth the money and effort).

I need more proof that it's worth upgrading the valvetrain on stock heads and cam. I heard the stock springs are crap... the car has 83k.

Jpack

iTrader: (12)

My wifes 96 TA put down 339/379 on a mustang dyno through an A4. All that is done to the car are heads got a valve job, 1.6 rockers, valve springs, coilovers on all corners, 3.73 gears and a cut out. I tuned the car VIA datalogs through email to the old owner that was out of state. Car ran a best of 12.9@109 on a drag radial. Car weighs 3625 with me in it and 1/4 tank of gas.

Catmaigne

iTrader: (6)

Sweet Jesus, all the numbers I come across are all over the place.

96TransAmboosted

iTrader: (8)

Im sorry but no way did a valve job new springs and RR NET you those numbers. 339/370 is cam only or cam and head numbers. I did not even read exhaust or intake on that. No way I call BS. I gained 11rwhpa on my stock lt1 with 1.6 rr but I already had mac mids installed.

ahritchie

iTrader: (1)

I have an old (1997-98) GMHTP magazine where they dyno tested all the popular bolt ons in sequential order and gave the HP gains.... First: CAI with pullies, 2nd shorty headers, 3rd 1.6 rockers with upgraded springs, and last was a 52mm TB. The 1.6 rockers picked up as much as 20 HP (*at certain RPMs) more than just CAI and headers....if my memory serves, the CAI/pullies was worth about 10 HP, shorty headers were worth about 15HP, 1.6 RR/springs was worth 15 PEAK HP, and 52mm TB was worth a whopping 2HP gain. Combined I believe they added 42HP over stock. So, anywhere between 15-20 HP gain.

bowtienut

iTrader: (1)

Catmaigne, It's more realistic and satisfying to concentrate on a performance goal for your car rather than a rwhp number.
Rockers and springs WILL be worth it. Regardless is the hp gain is 5 or 15, the extended rev range at the track will show up.
I picked up ~.10 sec ET/ 1 mph way back when I added 1.6 RR's and springs to my bolt-on engine. FWIW, it dyno'd 309 STD rwhp through an unlocked A4 with open exhaust.
If you don't care about track performance, then save your money, modify your "290 hp guess", call it a day and be just as happy.
Use a dyno for tuning, but don't chase absolute numbers. Case in point: Jpack's 339 rwhp claim through an A4 - just not possible, and his track numbers say so too. With 309 rwhp in a 3900 lb car, mine went 12.36 @ 107 ...... go figure ???

Jpack

iTrader: (12)

Not going to get into a pissing match over this. Car doesnt have a cam, only mods listed. Car is a factory ws6 which was factory rated at 310. I made one mistake and that was the type of dyno, it was a dyno dynamics which typically reads +1-2% higher than a mustang. I pulled the dyno that came with the car and it is posted.

As for the times it ran, yes could have been much better had the shift points been adjusted to not bounce off the limiter with the different sized drag radials. The 60' also suffered horribly and add to the fact it was the wifes first time ever down the track.

It is what it is and her car walks my sons longtubes, emissions deltete stock motor camaro.

Here is the dyno, I will post video later off my computer of the run.

coolmanvette75

iTrader: (2)

I made 293/338 on a dynojet thru an m6 with just LTs, 3" true duals, moroso cai, 160 t-stat, and a hypertech

Catmaigne

iTrader: (6)

The performance goal has always been 400 at the wheels since the car was purchased, something attainable with my current mods, a valvetrain upgrade, LE2 package w/cam, and a good tune. I want a track performer with decent street manners (not a dyno queen), I just haven't amassed all of the funds to make that happen as of yet. When I can afford the heads, cam, and everything involved in the overhaul I'll go right ahead, but I know for certain the rockers and springs will need to be beefed up as well. All I want to know is if it's worth the frustration to install 1.6RR's and stiffer springs on an engine with stock heads and cam for the time being. If it's worth 15-20hp on a bolt-on car, then sign me up. Ideally, I'd like to see a before and after rockers/spring swap OR some numbers of a straight up bolt-on car with new rockers/springs (and by bolt-on I mean LT's, catback, CAI, and tune).

Catmaigne

iTrader: (6)

This... those are some nice numbers for not even a mail-order tune... unless everything I've heard about the Hypertech is a lie.

The neighborhood fox is up and running which means the miniature horsepower war is just beginning. I have no idea what it's putting down, but I'm guessing it's a tad under 300. I will not allow this.

3 pedal SS

iTrader: (1)

Just do it. I guarantee you WILL feel a difference.

Catmaigne

iTrader: (6)

I've heard the exact opposite... that it will turn my car into a sewing machine.

Tbh, I don't really care. What ever is faster in a straight line.

ahritchie

iTrader: (1)

Read my earlier post....I already gave you these #'s bolt on for bolt on....you will not find the article on the internet....the LT1 bolt on dyno test it was WAY back in 1997 I believe when "GMHTP" was just "High Tech Performance" (they still featured Mustangs back then ) As previously mentioned, 1.6 rockers and springs were worth 15 peak HP and as much as 20 HP at certain RPMs on a dynojet....I got the magazine still in my bathroom LOL. They have been proven again and again to give .02 gains in the 1/4.

Prorac1

iTrader: (4)

I dont have any dyno numbers, but information is information I guess. So here it goes. Car was a 1994 Z28 with a TH350 and 10" 3600 converter. 3.73 gears and ET streets, car weight was 3560 with me in it.

Engine mods

1.6 RR
LT4 valve springs
Unknown underdrive pulleys
BBK shorty headers
Cutout in place of converter
Flowmaster American thunder cat back
Arizona speed and marine CAI
Tuner cat tuned by me, (probably not very well)

With this done the car ran 12.81 @ 106 mph with a 1.77 60 ft. shifting at 6000 rpm.
FWIW the car ran a best of 12.87 with the cutout closed.

This same combo is now in my 97 SS with a 6 speed, centerforce clutch and 3.42 gears. Still runs high 12s, but deffinately needs 4.10 gears. Motor now has 175,000 miles on it and still running strong.

Good luck with your quest. Eric L

Prorac1

iTrader: (4)

And FWIW, my car dosent get any false knock and dosent make any sewing machine noises with the 1.6 rockers. Eric L

Lawhead

iTrader: (14)

My bolt on car almost trapped 108 with out RR and springs I actually had all the parts to do it........and car blew up :/ not sure what the HP was but Id guess in the 265 to 270 range

ks my ss

Mine put down 335 hp and 350 trq at the wheels. That was with basically all the bolt ons. That was also with slp shorty headers and true duals.

I think I picked up around 15 or so hp with the rockers. I didn't do springs at the time. i didn't dyno it but I was seeing a constant 2 mph increase at the track.

lt1-xjs

I've been through the rocker swap 3 times, 1.52's, 1.6's and 1.7's. The 1.6 swap is like a 10-12 rwhp gain. If you are trying to get the most on the stock cam I'd go for the 1.7's. I switched from a s/a 1.6 3/8 Promag to a nsa 7/16 1.7. The dyno results netted me a solid 10 rwhp across the board gain for the rocker swap. My et went from 12.97 to 12.86. I'd also add an ewp and the ASP 945103 dampner set to your list. My car dynoed 309 rwhp with a best of 12.82 @ 104 at 3900 lbs.

Prorac1

iTrader: (4)

I think my results could have been better with better parts. My trap speed of 106 showed I wasnt making that much power, but it put it down pretty well with the 1.7 60s. Looking back I think LTs, and a better tune would have helped immensely. Eric L

bizerk1

J.w about doing 1.7 on lt1, what is needed supporting wise? and what brand rockers, y- terra?