Here is what I am planning on putting together:

Callies DragonSlayer 3.750
Eagle 5.850 Rods
SRP Low compression piston -16cc
Splayed 4 bolt billet main caps

I planning on using my NX wet kit with this setup up to 150 shot.

The heads I have on my 355 are a stage 2 porting but using stock size valves and no combustion chamber work. They flowed 265/190 at 550 lift.

What heads should I use or should I just use my old heads? I want to get the most bang for my buck just like any one else.

Michael

 

Bang for the buck, use your current heads. If you grab another casting + porting, your looking at thousands.

 

What CR are you aiming for? I am a big fan of low CR for a supercharged buildup, but many people successfully run a 150hp nitrous shot with relatively high CR. Obviously, as extensively discussed here recently, it's actually dynamic CR that counts. But the point is that you can use a relatively small nitrous shot without lowering the CR or using race fuel, provided you retard the timing and not try to run it lean.

In terms of heads, it depends on your goals and budget. On the intake side, nitrous will work the same no matter how much the intake ports flow. Of course, if they flow better you will make more hp independent of the nitrous. What you need to concentrate on with the nitrous is the exhaust side. That's where you will see a greater gain from the nitrous per se.

If you want bang for the buck, go with some flat top pistons, and use a little more nitrous. Cam selection is an issue as well. Are you buying a new cam?

Rich Krause

 

Rich,

Compression ratio: I dont want to have to be running race fuel, but I would like to get as much power out of the motor N/A. I would like to get the best of both worlds. I plan on using a timing retard box from MSD with my nitrous setup. My heads have stock combustion chambers. What is the a combustion chamber size of stock LT1 heads?

Cam selection: I am glad you brought that point up. I currently am using a CC306, I like the cam but I feel there is probably a better choice out there. Do you have any suggestions if I stick with my heads?

Thanks for your input.

Michael Kelly

 

If you are going to look at new heads it's really only worth looking at the AFR stuff now. The 210 and 220 LT4 heads are about the best thing to go to from where you are now. They need a LT4 or a Single Plane.

Rich is right, the cam is very important with N2O. LSA and exhaust duration need to change. I am a fan of High compression in a N2O motor, just use race gas with it and you will be safe. N2O is more like using Nitro Methane rather than using a Blower, it's changing the chemical composition of the fuel that's all.

If your heads have been ported they may have been milled to a stock chamber is 58cc, but it could be less.

Flow numbers are needed to pick out a cam.

Those rods are harder to pick out pistons for. I woud just go with a 5.7" rod if I was worried about that, but a 6.0" rod is going to give you all you need.


Bret

 

Michael: I assume you are talking about a street car that will sometimes be raced?

Most people using nitrous for this kind of scenario use a relatively high CR setup. Even with mega-buck race setups there was at one time adherents to both extremes. Some people advocated low CR with huge amounts of nitrous, others went for high CR with relatively small amounts of nitrous. I believe this has been resolved in favor of the high CR solution. Exactly how to translate this into what I am assuming you want to do is somewhat problematic. But overall, I'd urge a "high" compression ratio solution. You should be able to do this with good quality pump premium and high quality forged pistons. In this way, you will maxmize performance with and without the nitrous.

Cam choice is imprtant. The CC306 is not a good nitrous cam as it has way too much overlap. You need to chose the cam and the static CR before you chose engine parts. That is the first step. If you want to talk intelligently about cam choice, you need to specify a bit more about the car and your needs/preferences. These will in turn drive an intelligent discussion of heads. Is it a daily driver? It's a 4th gen, right? Manual or auto? Can you put up with a high stall if it's an auto or are you willing to change rear end gears? Optimzed for street or strip? Are you in a position to upgrade the entire valvetrain for high rpm use?

Lot's of questions, but it is not simple. Mismatched parts will be a waste of money and not produce an optimal result. Without more info we will be reduced to discussions like in "LT1 Tech" that go like: "the (blank) is a great nitrous cam" or "should I get stage 2 or stage 3 heads" or other nonsensical stuff like that.

Rich Krause

 

wrt camshafts,
Yeah, it's a popular subject in which a small group tends to get together and tell everything they think they know about camshaft design but might I suggest Michael that you do a search first. Otherwise we're likely to have to wade through the same information that's been given out in more than a few threads now. I don't really see much change in the opinions and the general consensus is that everyone should run a high lobe rate cam from one specific manufacturer.
Truth is, there are alot of good cam grinds out there. You'll see quite a few different manufacturers represented in the infamous Engine Masters challenge we've heard so much about..... Isky, Crower, Comp, Crane, take your pick. What's lacking is a good discussion on cam events and that gets you a little better understanding of how everything works and why. Maybe we could get there one of these days. Best of luck.

-Mindgame

 

Sorry if we are boring you! I am more familiar with the CC lobes, that's why I tend to talk about them. Why don't you share some information yourself, especially if you have a different point of view, that way we can all learn?

Rich Krause

 

Rich,

I don't think that Mindgame ment anything by that, of if it was directed toward you. If he did shame on him.

I though you were writing a paper or something on that, i'd be interesting in checking that out before it's posted/printed somewhere.

Yeah there are other good cam compaines, I'm with Rich I use Comp stuff and am used to it.

I've never gotten into a big conversation about cam design other than the lift vs duration one that Matt (96z) started a while back. Every engine and design is different that it needs different things. You can go from a HR 214/224 to a SR 247/250 and they both make stupid power. I guess it's the little posts here and there that complile alot of info for people on here. That and the billion books and things on the web that are one persons view of what cam designs should be. I just go from experience, it's hard really to quantify what goes where for me.

Bret

 

Rich,

I sent you an email. I detailed as much as I possibly could.

I would like to thank all of you for your help (Rich, Bret, Mindgame) I realize most of this has been hashed through in the past, but it seems to be specific to an individuals setup. I am a novice at this stuff and you all can go right over my head in hurry. I have read alot of your posts and I do respect your experience.

Any additional input would be appreciated. I would like to do this right the first time. My sig has details of my car.

The pistons I was leaning towards are 10.4 CR with a 58cc head. They have lowered ring lands and a thicker crown. The rods I wanted to go with would give me a little more piston than a 6 inch setup. The crank does not allow a 5.7 rod with out machining.

I dont have all the flow numbers right now but they topped out at something like 265/190 with stock size valves. Springs are comp 987s and comp R series lifters and manley pushrods, and I use pro mag 1.6 rockers.

Thanks,

Micheal Kelly

 

Whoop whoa slow down chief! I didn't mean for that to come across as a personal insult or anything. It wasn't directed at you sir Rich, just my ramblings en general.
I just think it's important that someone who doesn't know alot about cams to take the time to learn the basics of how a camshaft works.... hence my mention of the valve events. I just see this more as a learning forum vs a forum to come and get recommendations and a parts list. Again, nothing personal in that. Have a drink on me, I'll take a cold Albita Turbodog while you're at it.

-Mindgame

 

Thanks for the drink, compadre . I guess I needed that! Sorry for the misinterpretation.

Rich Krause

 

This link may help a bit with regards to your heads:
http://www.fierolt1.com/lt1_vs_lt4_2.htm

About halfway down the page you will see "* Combustion chambers are almost identical (there was a negligible .4cc difference) Volume for LT4 Combustion chambers are 54.4cc's."

When I had my LT4 heads cc'd, they came to exactly 54.4cc's. So in using 58cc's for your calculations, your CR may appear a little lower than it actually is. I went with the same -16cc SRP's you are going with, in my NA motor and I think it's a great street combo with the stock combustion chambers.
Cody

 

No sweat Rich.... I have done the same many times meself.

Stay cool!

-Mindgame