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351 Clevo + NOS advice.

2K views 13 replies 9 participants last post by  Behemoth 
#1 ·
Hey Guys...

I just wanted to ask your advice on what I should look at upgrading on my clevo to get it ready to handle a 150hp hit of NOS...

its an LTD, standard 351 excpet a holley 650, C4 in good nick and with a 2" s/steel exhaust...

the engine is need of a full rebuild just wondering what I should look at upgrading in the rebuild to be able to handle the shot of NOS.

Also down the track I'd like to hoow up a roots blower to the thing, so any considerations for this... I might as well do the rebuild right the first time.

Thanks guys for any advice you can offer...

Regards
Phil.
 
#2 ·
try to stick to low compression around 8.5-9.0 stay with the open chamber heads put 4v ex valves in. put good retainers and locks. put FORGED pistons in (they will be good for the blower or gas) also put moly rings in and arp rod bolts. also try to stick to a smallish cam as the bottle or blower will make it a large cam !! put on the best exhaust you can afford. the rest of it just go common sense and GOOD ignition.
if the revs aren't too high balancing may not be needed but if you put 302 rods on 351 crank it will . that option will put less side load on the bores so it may not split a bore so quick !!

Hope that helps
 
#3 ·
Make sure you compensate the NOS with enough fuel, and timing retard. If not taken into consideration, can be very harmful to you engine.
Best bet would be a wet plate system on your engine. Works very well.
 
#4 ·
yeah I was actualy looking at the NOS website and the undermanifold hidden system... looks pretty damn good actualy.

And i know that there are kits you can get that will let you retard the timing a few degrees from a sender unit and a dial in car.


basicaly if i go a head with it i want to try and make any mods to the car as hidden as possible, both from the cops and would be car thieves.
 

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#5 ·
These are fantastic systems, but not a very good thing for maintenance and modification. You also would have a lot of heat under the manifold, and this could atomise the fuel before it gets to the jet, which means the nos would not be compensated with enough fuel. Detonation equals expensive.
My opinion only.
If your running a carby plate system, they can be set up to be pretty un-noticable, especially of you have a 14" air cleaner on the carb, makes it very hard to see if there is a nos plate system on the vehicle.

Have fun.
 
#6 ·
351

You have to decide which way you want to go as a blower an NOS need two different kinds of engines.

Results with blower comp ratio without a blower will be very disappointing.

And i differ to the others on the NOS advise. Use as much compression as the engine will tolerate on pump fuel, and use closed chamber heads as they are more detonation resistant to open chambers. Detonation kills nitrous engines.
 
#7 ·
If your going to run carb then stick with the plate type. simple.

If your serious about the blower, consider when you might be doing the mod. if its a long way down the track or not. can you afford changing pistons for the blower build? :)

High comp/ratio is fine with nitrous, although depending what boost you want to run with the blower, lower comp/ratio is prefered.

See how you go :D
 
#9 ·
I'd also be wary about using any more than 100hp gas on a
stock 351 conrod. And if you want to go blown, it would be
like building a time bomb into your engine.
Do yourself a favour and pick up a set of steel rods,
at under a grand with bolts there cheap insurance compared to
what you would lose if a stock rod lets go.
 
#11 ·
Its all in the tune. When it comes to engine staying together. Even with strong pieces in there a bad tune will destroy anything !!! Its the total package!!
 
#13 ·
hey behemoth,

i will tell you how i did what you are looking at.
i had an xe fairmont that i put a 351 clevo in.
i used a super powershot nitrous kit.
it has 100,125,150 hp jets in the kit.
i never ran the 150 jets but ran the 125 hp jets.
when the engine was rebuilt i had 9.3:1 compression.it was bored 30 thou over
an isky cam,and all the crap that goes with it.
edelbrock dual plane manifold,holley 650 vac secondary with annular discharge boosters on the primary side,the lightest spring in the secondaries vaccuum housing
heads 3 angle valve job,port matched
extractors into a big single exhaust.
hypereutectic pistons
full balance blueprint
standard rods but prepped properly etc
i revved it to 6500 at the drags
ran nos through it alot and never had a drama

the car ran a shift kitted auto with a 2500 high stall.
diff gears were 3.5:1
i ran normal tyres at the drags
i only hit nos in 2nd gear got 13.4 ,(on the 150 hp jets and with traction and using nos in 1st 12.9 would have happened im sure but sold car.)
i ran a holley blue electric fuel pump,i had a hobb switch on the fuel side of the nos kit.
if you run nos use a bottle heater,dont hit the juice below 2500 to 3000 rpm.
the engine handled the nos with no problems,and i caned the car.

the engine had 369 hp with out nos so throw in another 100+ with the juice and it was a healthy combo.

i live in perth w.a and use to drive it 700 kms up to the bush to a mine i worked at i use to hammer the car with the nos on board and i only ever had one breakage and that was the tail shaft housing on the auto shattered,all that torque(but that was an error on my part,because i was told not to hit nos when in third,i was told to clip it back to 2nd i didnt and paid for it ,although a tail housing breaking is not much to worry about.i raced it for 2 yrs

the kit plus extras set me back about 1500 all up roughly

i hope some of this helps
 
#14 ·
Thanks for all the advice...

I'm hopefully going to start on the rebuild soon...

and as soon as i get the cash i'm probably going to go with a plate system to make things cheaper and a bit easier.

one of the things that I am 100% going to do regardless of any other upgrades is to go for the best bottom end that i can afford...

But thanks for all the advice.
 
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