[Sebro1231]

I know some of you guys can help! Not a gear head so I need the "skinny" on this.
I want more "red light to red light" fun. Car performs good now but trying to get a little quicker w/o big bucks.
Current Set up in 65 Malibu
Block 1997 Vortec 355
Scat iron crank, forged 20cc dished pistons
GMMP LT4 Hotcam Duration @.50 210 /228 Lobe Sep 112, Lift with 1.6 .535/.525
Heads 97 vortec came on the motor but blended bowls and short side radius worked,
1.6 rollers, beehive springs
Fuel RPM Airgap, Demon 650 VS, Holley mech. pump 7.5 psi
Elec. GMMP HEI w. Pertronix upgrade, and Second Strike Box
Drive 3.73 rear / 700R4 Trans / 255/45 rear tires

Hot rod friend says cam ok but will improve acceleration to replace the 1.6 rockers with 1.5 rockers and that's the cheapest way to get there. Would like more "seasoned" opinions.

I have the car equipped and plumed for NO2 but been scared to fill the bottle after reading not to "hit" an engine with 100 shot that is making over 350 hp on iron crank. I guess I am currently around 400. What do ya'll say and will going down to the 1.5's deter future NO2 thoughts?
Thanks,

 

[Andy's Auto Repair]

Last first. The only way you will NEED that forged crank is when you spray it and it breaks. Seriously, be spot on the tune and that 100 shot will harm nothing. Stay conservative, use a quality timing light. Pull a full 4 degrees out when you hit the "Go baby Go" button.

Rockers, 1.5 versus 1.6. All truths begiven, rockers are the fulcrum the pushrod uses to open the valves. Increase the ratio, and mechanically you will have more lift and duration. Is a $300 set of qhality rockers worth the 5-10 hp increase you might see after altering the tune? Only you can answer that.

 

[novadude]

If those are really 20cc dish pistons and not 12cc dish, you have no compression. Even if your set-up has a tight piston-to-head clearance, you are still < 9:1. I wouldn't put 1.5 rockers on it - that Hot Cam was designed to run with 1.6 rockers, and I don't think going to a lower ratio will pick up anything. Your best bet would be to get some flat-top pistons in there for ~9.7 to 10.2 CR, or 12cc dish for 9-9.5 CR.

 

[Sebro1231]

Thanks for the responses. I wouldn't want to spend 3 to 400 for a 10hp gain that I would not feel. Even with the dished pistons (did it for the poor gas vs. detonation) ... car runs pretty strong. It is just a w/e crusier.

 

[Dave Birdwell]

You want something for stoplight-to-stoplight??? Don't touch the motor, just install a set of 4.56 or 4.88 rear end gears and some sticky drag radials and hang on. :yes:

 

[CharlieB53]

You want something for stoplight-to-stoplight??? Don't touch the motor, just install a set of 4.56 or 4.88 rear end gears and some sticky drag radials and hang on. :yes:

Gears will give you the biggest seat of the pants improvement.

Forget the 1.5 rockers, you will actually lose a couple HP with less valve lift.

I don't know which gear set would be best for your application. You might try finding something like Desktop Dyno, plug in all info on your car and run a few sims, make gear changes and see how the sims change. This may help you decide which gear set may be better for your use. 4.11 aren't bad on the street, 4.56 and higher can be a little much if you put a lot of miles on.

 

[Dave Birdwell]

He's got a 700R4, so overdrive will be like running 3.45:1's

 

[Orr89rocz]

Tires and a torque converter and spot on tune. That will wake up that motor. Hotcam is 219/228 .525 with 1.6's. good little cam

 

[novaderrik]

Thanks for the responses. I wouldn't want to spend 3 to 400 for a 10hp gain that I would not feel. Even with the dished pistons (did it for the poor gas vs. detonation) ... car runs pretty strong. It is just a w/e crusier.

those dished pistons were a mistake on your part: i was running flat tops, .015 shim head gaskets, vortec heads, and the HOT cam kit with a cast crank in the 355 that was in my Nova and it ran all day long without detonation on 89 octane E10. the machinist that did all the work on the parts before i assembled it said it was close to 10:1.. it was a beast from it's 700rpm idle speed to the 7400 i saw on the recall tach i don't know how many times in the 4 years that motor was in that car. i ran some thick head gaskets (machinist said it was around 9:1) when i first built it in a misguided attempt to keep detonation at bay, and it would rattle like crazy on 93 octane... just swapping in the thin head gaskets got rid of that problem and gained me a ton of throttle response, torque, high rpm power, and even a couple of miles per gallon when driving it as my daily beater.

to answer the question you asked: keep the 1.6 rockers... GM spent a lot of time and money developing that cam to use those rocker arms in LT4 powered showroom stock endurance road racing Corvettes, and to just throw some 1.5's in there throws a lot of that r&d cost right out the window.

 

[CHELKAMINO]

It is just a w/e crusier.

Just curious.....if it is just a w/e cruiser, then why the bottle?

 

[Sebro1231]

Heck .... I don't know. I've got the purge lines run up thru the cowl grill with blue LED lights. Thought the blue cloud would look cool in a night parade.
Also like acceleration but too old for the high speed.

 

[chassis man]

100 Shot with a good timing retard box and good fuel you wont hurt anything. Best to lock out the distributer, I wouldn't use it with mechanical or vac advance. Once you've tried it you'll be getting your bottle filled every week.