smoktire

I have run 12.45@109 with 75HP (NOS) 12.40@110.6 with 100HP
and 13.17@104 on motor. Its a 2 bolts main stock rods cast crank and Speed pro hypertectic piston.All stock nuts&bolts.I open the nitrous at 2400RPM....Does it will survive 125HP or 150HP my goal is 11.9X@11X....

Car wheight around 3650LBS

88IROC350TPI

As long as your tune is good, I dont see why not.

unknown_host

iTrader: (1)

I think 150 will be fine as long as you are pulling timing, running good gas, have a good ignition system and are checking plugs. Here is an article I posted a while back:


I was reading a book i have about building small block chevys on a budget. I am sure everyone has read about how hypereutectic pistons are bad for nitrous and how they are prone to cracking. Here is a blurb from the article, let me know what you guys think:

"It has been found that using 18% silicone to make a hypereutectic alloy has improved the material for high performance pistons while keeping costs nearer that of regular cast pistons.

The only drawback to producing hypereutectic pistons is that the free silicon in the aluminum wears out regular carbide machine tools much faster than non-hypereutectic alloys and mandates the use of diamond tools. As far as use in a performance engine is concerned these alloys are really what the high performance street engine builder was looking for. Because casting allows metal to be put exactly where it is believed to be required, hypereutectic-cast pistons need not give away any real strength advantage to a forged piston. With forged pistons the forging die must be removed from the forging so undercuts in pin bosses cannot be directly formed. To make a forged piston significantly lighter than a cast piston requires much more machining. Because of the process and material involved, hypereutectic pistons are just about as strong as forged pistons but can be run with much tighter initial clearances and wear much slower. Just before Sealed power introduced its first Chevy hypereutectic piston I was sent a set to use in one of my street nitrous motors. About 50 pulls on nitrous at levels wtween 530 and 560 hp had no visible effect on them. Since then, several other companies have produced such pistons. The most notable is Silvolite with the Keith Black signature series. Although a little heavier than some of the lighter forgings, these pistons are proving to be race tough. I have used them up to almost 600 hp and there are racers with blown motors making several hundred more than this who are making it through several seasons on the same pistons. However, for this kind of reliability with cast pistons, I recommend modifying the block so the pistons are oil cooled... Without the aid of oil cooling, I limit the amount of nitrouspower augmentation to 150 horsepower when using hypereutectic pistons."

smoktire

My tune should be ok since i use the recomended jets and using a low fuel pressure switch that turn off the nitrous if the pressure get below 5 psi.For the ignition Accel coil & MSD6AL box
thanks

unknown_host

iTrader: (1)

Do you not like your 6AL box? How much timing are you pulling? Just a suggestion, I run the MSD Start/Timing retard add on box with my 6A and I can pull however much timing I want based on pills I select when the nitrous button is pushed. Got it off ebay for under $100. Not sure how you have yours setup but it really helped me get out of the hole on passed where I wasnt spraying off the line.

smoktire

Thats is a nice idea for the timing retard but does it pull the timing all the way to the red line? For the timing i got 12 initial 35 total at 3000rpm.The nitrous is hocked up with a MSD windows switch on at 2400 rpm off at 5900rpm i run 94 octane gas.Yes i apreciate my 6al

smoktire

Is the timing reatard box is pn: 8970

unknown_host

iTrader: (1)

It pulls timing all the way to redline as long as the nitrous is engaged. When the trigger wire on the MSD retard is to ground, the timing is normal. When the trigger wire is removed from ground, it retards the timing. So if you wire the trigger wire to the positive side of your nitrous solenoid, it will ground itself within the coil in the solenoid when the nitrous is off, and when you engage the nitrous it will remove the trigger wire's ground and retard the timing. In your case, when your window switch cuts the nitrous off at 5900 rpm it will also return the trigger wire to ground and advance the timing until the nitrous comes back on.

EvilCartman

iTrader: (1)

Hummm, might have to get me one of those btw unknown_host, after all this time I've that cheater setup, it'll be done tonight Trying it out at the track maybe next month depending on how things go.

unknown_host

iTrader: (1)

lol nice, yeah I was lazy with mine too . I think I had mine a good 6 months before it got installed lol. And I still havent made a real pass with it .

smoktire

Just to warn thoses of you running speed pro hyper piston ....100HP of nitrous is the MAX you whant to go...I put 125HP and piston no 4 and 6 are now in pieces (yes the fuel pressure was good) .So now i got my ansew Times for a forged 383

unknown_host

iTrader: (1)

There are LT1 cars that run 175+ HP shots for several seasons. Have you been reading spark plugs? Do you have a means to watch the fuel pressure all the way down the track?

smoktire

i got a low fuel pressure switch set at 5 psi along with a aif fuel ratio guage.

razor

Did you have 35 degrees total timing on 10.3 iron heads???? What plug were you running??? It sounds like you might have had too much timing. Did you ever read the plugs after a pass????

smoktire

r44lts the ar guage still ok

razor

Seems like too hot of a plug with that much compression and timing and a 150 shot. My car is totally different but for an idea my stock plugs are R45TS. I bumped compression to 10.5:1 on stock 083 heads. After the rebuild and before nitrous I had to run 2 ranges colder, down to an R43TS. I also brought my total timing down to 25 degrees total timing. With a 100 shot I run a R42TS plug and two degrees less timing so 23 degrees total timing. I run the car on 91 pump gas which is the highest octane in my area. My guess is you had some pretty heavy detonation.

eric17422001

I have also "HEARD" that a dual plane intake does not distribute the intake charge evenly using a plate type nitrous system and some cylinders run leaner than others-leading to piston failure.