NOS and Compression Ratio

[jreiley]

When I rebuild my sbc this winter I'm thinking about building it so I can put a 100 shot of NOS in it. What is a good maximum comp ratio to use. Race only - no street.

[TS1955]

I'm working on a Top Dragster with a 572 BBC with 15 to 1 compression. It has 2 stages of NOS. A plate and fogger.

TS1955

[russ67chevelle]

im starting to wonder if u really are looking for a race only set up,thus i may add that i wished i told my engine builder the truth when i ordered cam,cause i told him 90 percent race 10 percent street, because it is a terd below 5000 rpms, hence i should of told him 50/50.

in another words be truthful on goals and dont think you need the bottom of the page cam when your never gonna take it above 5000 rpms...

good luck, trying to help u here sorry not trying to insult.

you have shouldnt have no problems putting 100 shot nitrous in a bone stock motor,but biggest upgrade to consider is forged pistons in 2618 aluminum.

the cheap srp and other "forged" pistons of 4032 grade aluminum are not as well suited for heavier doses of cylinder pressure like nitrous blown or turbo rigs

[OneBadGMC]

Hell, I've sprayed 250 HP through bone stock motors. It's all about controlling detonation and proper a/f ratios.

That being said... A motor designed for all motor will have a lot of waste when nitrous is added. A motor designed for nitrous every pass will run like crap compared to a motor designed to run n/a.

[jreiley]

This car is a 1/8 mile car now. It runs in the mid 7's. The engine is at a point it needs to be refreshed, so instead of just tearing it down and honing and putting in new rings and bearings, I want a little more oomph out of it. Hence the question about nos and compression. The block is a gm block as are the heads. The heads have had a lot of work done to them and are port matched to the intake and exhaust manifolds. Bronze guides in the heads, big Lunati cam, msd and all the normal stuff. Car weighs in at around 3000. Anyway it appears compression is not a issue.

[bjuice]

like gmc said its about controlling the detonation and a/f ratio.

if you gonna spray around 200 shot..place forged pistons in the engine and a middle of the road CAM that will still have some ok bottom end on motor passes and wide enough lobe seperation to reap the benefits when you spray it....remember you can't have the best of both worlds with sprayng and running strong on motor

make sure you have more than adequate fuel supply, and Knock a minimum of 2 degree's of timing out per 50hp of Nos used

also use Good Fuel when spraying..minimum 110 octane..112 ain't a bad thought either.


ohh yes if its race only..don't waste your time with 100 shot...your wasting your time and money...Hit it with 200 minimum or stay away from it.

[ashbros]

with a small block i would not consider spraying less than a 150 shot.

A street motor for crusing 100-150.

A lot of guys around my area tend to run 12 to 1 compression, with race fuel. The nitrous seems to respond quite nicely.

On another note, back when my boys were 14 a6 16, I gave them a few bucks to throw a little budget motor together, It was built for the use of nitrous in mind except their budget did not allow them to use forge pistons.

Stock block 4 bolt 355 CID
Gm Steel Crank
Stock GM Rods with arp Bolt Upgrade,
Hyperutectic pistions - they were cheap....
The cam was not to big 515 lift intake and exhaust
I had a super nice set of brodix track 1 heads that had been work over by Ron's porting
Strip dominator intake
Jimmy Evans 950 Blower carb
125 Shot of Nitrous.
clevite bearings
Can't remember what rings they used.
On the nitrous this was a really strong motor, but the thing that caught my attention was the boy ran a bill up at the neighbor hood nitrous refill depot. They ran over 100 bottles of nitrous though that motor and bolted on a little 142 blower before they blew it up.. and this isn't no fishing story......

Now once they bolted on the 142 that little motor had all the power it needed without the nitrous, but hitting that switch made it soo much more fun...... :twisted:

Moral of the story.. Go easy on the nitrous, with proper a/f ratios your motor just might last a few extra passes..

Not bad for a couple young teenagers

[russ67chevelle]

this is a good time to advise for everyone if running nitrous or not, one of the best tuning aid is an air/fuel gage.

i bought an aem gage.all i did is welded a bung on collector and plug er in. thats it,now i can tune my 3 circuit dominator with it. for around 300 bucks or less perhaps,i paid 260 to my door,awesome investment!!!!!plug a camcorder on your roll cage and record.enjoy!

[jreiley]

Thanks to all for the info. One other question - any NOS vendor better than the rest for sbc applications?

[russ67chevelle]

your gonna hear a ton of diffrent opinions, but if i had to do it again id look at the cold fusion line of nitrous, cheaper than the big shot kit i have...but 100 bucks cheaper....http://cgi.ebay.com/ebaymotors/Cold-Fusion-Nitrous-Plate-Kit-200-400HP-4150-4500-N20_W0QQcmdZViewItemQQ_trksidZp3286Q2ec0Q2em14QQha shZitem2ea7623e93QQitemZ200376729235QQptZRaceQ5fCa rQ5fParts

[suicidebomb]

Ash, if my failed minnow joke to oldandtired the other day, came off as accusing you of "telling fishing stories", I appologize. I was telling fishing lies to oldandtired. Once again I appologize.

[bjuice]

with a small block i would not consider spraying less than a 150 shot.

A street motor for crusing 100-150.

A lot of guys around my area tend to run 12 to 1 compression, with race fuel. The nitrous seems to respond quite nicely.

On another note, back when my boys were 14 a6 16, I gave them a few bucks to throw a little budget motor together, It was built for the use of nitrous in mind except their budget did not allow them to use forge pistons.

Stock block 4 bolt 355 CID
Gm Steel Crank
Stock GM Rods with arp Bolt Upgrade,
Hyperutectic pistions - they were cheap....
The cam was not to big 515 lift intake and exhaust
I had a super nice set of brodix track 1 heads that had been work over by Ron's porting
Strip dominator intake
Jimmy Evans 950 Blower carb
125 Shot of Nitrous.
clevite bearings
Can't remember what rings they used.
On the nitrous this was a really strong motor, but the thing that caught my attention was the boy ran a bill up at the neighbor hood nitrous refill depot. They ran over 100 bottles of nitrous though that motor and bolted on a little 142 blower before they blew it up.. and this isn't no fishing story......

Now once they bolted on the 142 that little motor had all the power it needed without the nitrous, but hitting that switch made it soo much more fun...... :twisted:

Moral of the story.. Go easy on the nitrous, with proper a/f ratios your motor just might last a few extra passes..

Not bad for a couple young teenagers


Ash you got any small block heads u wan to get rid of ?..looking for some heads for this procharger small block i am building...i just don't trust buying anything like this from someone far off i do not know....you know where i am coming from here.

i have dealt with Big Blocks for so long..i have Nothing but a few small block intakes laying around...

thanks Brian

[ashbros]

Ash, if my failed minnow joke to oldandtired the other day, came off as accusing you of "telling fishing stories", I appologize. I was telling fishing lies to oldandtired. Once again I appologize.

LOL LOL 8)

suicide,

This is what I refer to as a fish story.

[/img]http://i555.photobucket.com/albums/jj462/ashbros/1BigCat.jpg

In no way did I consider your comment negative....
LOL 8)

No not at all, I was just speaking in general....
Matter of fact I find a lot of your postings quite humorous and usually can't wait to see what ya come up with next...

B Juice, Let me do a Little digging, I just might has something your looking for.
[/img]

[suicidebomb]

Cool

[chevyfireball]

Y'all gotta remember, the higher the compression, the higher octane fuel you wanna be running to help avoid detonation. My 632 is 14.5:1 comp. I run 700 hp nitrous through it and C16 fuel.

You'll probably want to run 100 octane or better, maybe C12.

[TheRabbit]

Thanks to all for the info. One other question - any NOS vendor better than the rest for sbc applications?

Speed Tech is the most advanced NOS on the market right now!

This is a small block with a fogger with 2 stages and 2 plates. All total a little over 800hp of NOS on a small block!! :shock: It's UGLY when the bottle of whoop azz opens the wrong way!! About every 10-15 passes it gets new rings. Look under the front of the intake. It was a nightmare to plumb!! :x :x

http://i163.photobucket.com/albums/t288/rabbit548/RandyRoberts.jpg

[bjuice]

the WABBITT ON STEWIODS !!!!!! :shock: :shock:

[TheRabbit]

the WABBITT ON STEWIODS !!!!!! :shock: :shock:


That's not the Rabbit motor. It belongs to Randy Roberts. He gets on here every now and then. His profile name is gimmemud on RJ.
http://i163.photobucket.com/albums/t288/rabbit548/RandyRoberts-1.jpg

I do all the teching at our (MRA) races so I get a good up close look at what everybody's got!!

[fla1976]

I guess he could name that engine ARNOLD. Must be a sight to see.

[russ67chevelle]

HEE HEE HEE

[oldandtired]

Yeah, Randy told us he had a fortune in hose and fittings. Dave

[gimmemud]

Well it looks like all that money in hoses and fittings paid off. :lol: I have removed the plates and now only run 2 foggers.

I have had a very good season so far, out of 17 races I have enetered this year I have won 14 of those, 1 second place and broke at 2 (valvetrain related) and set 2 National Records along the way.

Here is a video of the last race in South Haven Kansas.

http://www.youtube.com/watch?v=8-AmE3EPUw4


Now a little on the topic of compression. You can make more horsepower with nitrous than you can with compression if you build with heavy doses of nitrous in mind. My little 435 ci small block is only 13.6-1 compression, and has oner .100 thousandths quench.


Dont let that Rabbit fool you, that thing he has runs hard too.

[demented]

Yeah, if Randy keeps it up, I'm going to have to start pulling off some of his plug wires just before he runs. Thats is one fast small block!!!!

[chrisr]

I have never thought about mud racing until I saw yall's stuff. Do you ever come to Texas, if so where? Me and my boys will come and check yall out.

[cepx111]

Cool video, congrats on the wins and records.

You could really see when the squeeze was hit, that thing took off like a bat outta hell. Wicked... :twisted:
Cp

[Tod74]

Very Cool video.

[chevynovaman]

AT WHAT POINT ON COMPRESSION RATIO AND NITROUS TOGETHER SHOULD A GUY RUN MLS HEAD GASKETS OR ORINGS??? I HAVE HEARD OF HIGHER COMPRESSION ENGINES ON NITROUS BLOWING HEAD GASKETS BECAUSE OF TO MUCH CYLINDER PRESSURE.. THANKS