Building a Motor for N02

[Dr.Evil]

I am looking for input on what should be done to a SHO motor for it to handle a 75HP shot of Zex. So far, it is a 3.0 bored .30 over, crank turned .10 under and indexed, port matched heads, and custom Ross pistons. Stock compression.
What rings should I go with? Also, will the stock fuel system be okay for this set-up?
Anything else I should do to the motor (crank & rod ballance, beefier cap bolts, etc)
One more thing, what is a good N20 clutch/TOB? I have a fidenza that will be mated to it.
Thanks for any input.
-Matt

 

[RStalveyARFF]

Here's my .02 take it for what it's worth. You don't really need to "build" a SHO motor to run a 75 dry shot of Zex. What you do need however is all maintenance done. Main and Rod bearings would be a good idea, a free flowing exhaust (not too big though which would hurt NA performance), brakes to slow the beast down. A quick motor mount check would be in order. A 190 LPH pump would work well, as would a nice MAF. Ditch the LPM and 80mm Ford MAF, it will not work well with the juice. As for a clutch, You're pretty much just looking for something grabbier. A stock clutch will work, but it's longevity will be affected. As for the Fidanza, I'm sort of hesitant for saying it'd be a good match. I know Mark N had problems after switching from the stock FW because he lost a lot of surface area due to the holes for the screws. You may be better off with A the SS 17lb steel, or B your stock flywheel lightened.

<small>[ February 24, 2004, 08:51 PM: Message edited by: SHO91MTX ]</small>

 

[SHO--ripper]

I second that 91MTX, i bought a SHO for $200, threw some copper plugs in it, a catless y-pipe, and had a 70 shot of NOS on it. The motor was fine on the car when i parted it out. The only thing that ever happened was a slipping stock clutch b/c of 250+ hp, a broken motor mount, and seperated exhaust. A stock motor is fine, but since you're already building it, i think you should sell the fidanza, and go with the stock/steel flywheel. Get some cold plugs; copper or iridium.
Use a ceramic TOB,and i've heard good things about mikey's new clutch. If i were you i'd get some ASB's, and other suspension mods to keep the power on the ground. Lastly a quaife would be a good investment, and some drag slicks. burnout

 

[RStalveyARFF]

Oh yeah, I forgot about the copper plugs. Oops!

 

[Dr.Evil]

Yea Im already building it so I just want to make it as sturdy as possiable, even though the stock SHO motor is really tough.
Should I spend the 150 to get the internals ballanced? Also, is there any benifit of shifting at say 7700 if everything can take it (besides the staying in one gear longer) I will get some UDP's to protect the acessories, but when do valves start floating on these motors?
So the Fidenza is no good with for nitrous? Ill look into the SS 17lb or ask the machine shop to lighten one for me.
I am hopefully going to get in on the headers, so the exhaust will not be a problem
Already have nice SHOnut motor mounts and AL SFB waiting to go in.
I know a Quiafe would be sweet, but Im not sure if I can afford it yet.

 

[RStalveyARFF]

what internals are you talking about? new pistons or old pistons? You will have to get new pistons balanced in the assembly if you go for it. Personally though I see it as a waste since stock 3.0 shortblocks have seen more power through supercharging than a 75 shot will ever produce. If you're really really concerned, just get some new rings, some new bearings, and be done with it. Also, shift so each time you get into your next gear you're in the middle of your powerband. I'd suspect 7700 would be too high, since you usually peak around 6000, and your torque is already heading down hill.

<small>[ February 25, 2004, 02:58 AM: Message edited by: SHO91MTX ]</small>

 

[Dr.Evil]

The pistons have around 15K on them. The block will need to be honed/cross-thached. The pistons, block, rods, crank, and heads will all be dipped so they will look brand new.
I mean ballancing the rods and crank. I did this to my 351C and can safly turn 7K, but the valves float and the cam/intake drops off. I also added ARP rod bolts to beef it up. It will never see this this high of RPM, but it will last longer than if I didn't do it with less of a chance of something failing.
So basically would this be necessary to build a pretty much bulletproof motor? I don't plan on having the baddest NA plant around, but if I am going though the trouble of the rebuild, I want to do it right. I just don't want it to blow on me after I put all of the time/effort into it.

 

[Dr.Evil]

well the it has already been ballanced. I think I will just add some ARP rod cap bolts, all new bearings/seals, and be good to go.

 

[Hack]

Its not so much that the Fidanza is bad for use with nitrous, as it is not well suited for drag racing.

 

[National #19]

Here is what i think...I wouldn't put a 75 shot into a freshly rebuilt or built motor at all...For one thing, yess its very sturdy and strong...That means for things are tight and there is less cushin for any error like too much n2o? I would put a 75 shot on a motor that is well broke in and not a fresh one. But yess do maintaince before you do run any nitrous. But i really don't think a 75 shot will hurt anything like you are doing anyways.