A few ?? for the Nitrous guys....

Several companies make progressive nitrous controllers that pulse the solenoid at low rpm so nitrous quantity is limited and you can start flow at a lower rpm. I'm running a Jacobs unit on mine. It's adjustable from the driver's seat so if you're having traction problems you just turn the knob and decrease the shot.

 

BMCDaniel basically hit the nail on the head, I have seen guys hit the spray at a low rpm.....I even know some guys that actually activate there nitrous just a split second before they leave the line, while they are still leaning on the converter!!! yikes!! I think they say not below 2500 basically for safety reasons. Think about it, any hot car at the strip is gonna be footbraking or t-braking at over 2500 rpm. My 2-step is set at 3500 so it's not even an issue!! In my opinion 3500 is still conservative!! I don't think that will be an issue for you John. The only bad thing i've heard about the progressive controllers is that they can be hard on selonoids but I think that's coming from people that have had no experience with the Jacobs unit. I've heard good things about all of Jacobs products though!!

 

Thanks!
You guys are smart!

Preshehadit!

 

i know this is an OLD quote, but i have a question since i will be running NOS in my 347. heres some quick specs though...

71 302 block
bored .30 over
347 stroker from coast high with the 5.315 rods
forged probe pistons around 10.0:1 compression
cast rods and crank
main girdle but no stud girdle, screw in studs though...
HV oil pump w/ hardened shaft
also running felpro head gasket, not copper...
edelbrock rpm airgap intake and rpm alum cyl heads and rpm cam
summit 110 gph(free flow) mech fuel pump with 3/8 line all the way to the tank.
holley 750 4160 vacuum sec although i will prob rejet to 650...if need be.
the 347s externally balanced at the 28oz and had the stroker kit balanced

how much can i safely spray? i was told 100 shot since the 100 is guaged at the wheel and its more like 125 at the flywheel... and another question is if i had an rpm activation switch that cut it on at say 3,500 then cuts off at 6,000, if my engine runs to 6,500 on the cam and head set up, when i shift out of 2nd at 6,500 it will be off? then will it cut back on when i hit 3rd gear and brings it back down to around 4,500 or so? just asing.... thanks guys...

 

In my Coast High/Probe 347 with the Jacobs controller I used to run a 150 shot. With that controller's ability to ramp the shot and babysit the engine I could have probably gone a little higher but those were the biggest jets I had.

 

you should be able to run at least a 150 shot with the 347. the important thing with nitrous is to avoid detionation. so up the octane and retard the timeing. with nitrous the motor will want to rev past where off the nitrous it falls off as long as your valve springs are strong enough for the rpm. so if your motor revs to 6500rpm before you shift then put a 6500 rpm or slighty higher seting in the window swith that you use for the nitrous.

 

so if i bought the nos powershot factory preset at 125, i should be ok?..... i was told i needed a bigger fuel pump because since i'm making 400hp a 100 or 125 would put me over 525 or more at the flywheel and my block/fuel pump couldnt handle it....

but, with any question, a million people have input, so i seem to value everyone on heres a lot more... thanks guys.


OHHHH and, how are the nos plates that go under the carb, good? problems? how about with the airgap which is a dual plane...? thanks for info...

and which jacobs controller...I.E. part number/cost?

 

I assume you have a mechanical pump? Depends what fuel pump you have, I ran a Carter street pump that's supposed to handle 500+ hp. The main thing is to use big enough fuel line to allow the pump to do it's thing, 3/8" minimum. You might also want to run a check valve at the tank, keeps the fuel line full under acceleration, gas can't flow back into the tank.

You will be reaching the limit of a stock block.

Plate systems work ok with dual plane intakes, double check that the plenum divider doesn't interfere with the spray pattern. You can also taper grind the top edge of the divider.

Jegs and Summit both sell the Jacobs Nitrous Mastermind for around $225.

 

yeah its a mechanical pump supposed to flow 110gph free flow, i have 3/8 line all the way back...and yeah, the block might be an issue... i might go conservative for a 100 shot and no more... hmm..


maybe i'll swap to an electric before i put nos on, and grinding the plenum divider might be a good idea, it is kinda squared up top...

 

definty run a second pump. im runing a dedicated fuel system for my nos cheater plate system jeted for 150hp. you may want to consider doing that. i had the jacobs mastermind. i did not like it. i only ended up useing the timeing retard feature. the othes all sucked. the progressive was it turning the system on and off. so you would be jerked rapidly untill it came to full shot. this was rpm based so it would do it in each gear when it was only needed in first. i have a msd digital 6 and a msd rpm window switch. these are all the eletronics you will need to controle your juice. Ive ran plate systems on the performer rpm intake with out ever grinding the divider. the patern out of the spray bar wont have a problem with the divider.

 

Heating Nitrous Bottles

Nuff Said.

 

What is (was) that?

 

I never had a problem like that with my Jacobs unit, but I would only switch on the nitrous in 3rd and 4th gears, not enough tire and suspension in my car to use it in lower gears. The mention of the MSD brings up another point. You don't want to run nitrous using points ignition, points bounce and can cause spark when you don't want it. You need accurate spark timing.

 

i'm running a GM HEI type distributor for the 347, so points are not an issue.... so i could keep my mech pump for the engine and run an external electric for the nos only? sounds good... and i was looking into the MSD stuff for the engine retard and window switch....