what does the dcr mean to me?

The static i understand somewhat along the lines of more power and of course i run race gas (i think i should have been running more than 110 vp last year with these numbers)

STATIC COMPRESSION RATIO 14.934

DYNAMIC EFFECTIVE COMPRESSION RATIO 11.568


What lifters do i use for a solid roller cam in this block? part numbers would be too great

These are stock casting lt1 heads so about springs,cups and retainers? what can i do for lift in the 650 range?

I have stock length 2.02/1.60 race flows will i have to get longer valves now?

maybe longer pushrods? i run 1.6 crane gold rocker arms the kind you dont need guide plates with will they still work?

Also spark plug recomendations i went with the coldest ngk made for our reach ran good for 2 days then started missing till i made 5-6 passes. should i try to find colder or go hotter?

If ya got a DCR of 11.56 ya better run it on nuclear fuel...
DCR is what the engine actually "see's" and runs on.
Crower HIPPO or Isky Red Zone or Shubeck for a SBC,ask them.
Call your cam manufacturer and see what they offer in a 250/260@50 with a .400-.410 lobe lift= .656 lift on a 108+4. That may be more cam than ya want on the street,but she will run.
Probably have to get longer valves for spring seat pressure in the 225-250 range and 650-700 open pressure if ya are going to turn it 6500. Maybe a little less but not much.

Longer valves=longer PR's
Run stock heat range in the brand of choice with no exotic metal-- just standard plugs at .035 gap
Never ran SA rollers on a mech roller,but I wouldn't. Your lash will be HARD to set and because of the lash(.025-.030) I think they will come off of the stem in no time. BIG mess,lots of extra money to fix.

I only put 400 street miles on it last year so thats no concern to me.

Your going alittle fast for me i will have to reread this a few times till i understand fully but thanks very much

sorry if it sounds like i am asking you guys to build me a motor i just forgot most of the info from 2 years ago when i first put this together at one time though i knew quite alot

No problem on the info.
If I wasn't going to run it on the street I would go bigger with the cam depending on head flow.
No the mech rollers have a tie bar built in and they are permanent pairs.
The higher octane is it. When ya figure a 75* IVC in there it's going to drop down quick.
The 225-250 is the amount of spring pressure put on the valve when it's on the seat and the 650 is what the pressure is on the nose of the cam(max lift)
Push rod length will have to be mocked up and checked then order the PR. Every engine is different.
Run NSA with the guide plates made for your head and get them and the PR at least 3/8" dia. THICK wall for that much spring pressure.

I think it's good that people are concerned with DCR but I think it takes a back seat to some other issues when dealing with a race car. DCR is not any representation of what peak cylinder pressures will be or the rate of rise in pressure. DCR doesn't take VE into consideration and that is a big factor to deal with here. And of course, DCR does not take vehicle weight and transmission type/gearing into account. So what should we be really looking at for a race car build anyways? Back to the topic....

So you're running ~15:1 static and ~11.6:1 dynamic..... how good is the induction system?

If your VE is high, you will likely have more problems with higher compression. If the VE is low, you can get away with more compression. Running a factory intake with low port 23 degree heads is IMO not the ticket to really good VE unless they are seriously worked over.

If the car is heavy (3100+ lbs) running on the converter alot, it will likely have detonation problems with very high compression. Guys running heavy powerglide cars in various race classes often times find better times with a reduction in static comp. for this very reason.

All in all I don't have a problem with your 11.6:1 dynamic. Some of my old race engines were about in that range but with much better induction systems. You might want to start with VP C25 & see how she does. If she rattles you can step up to C19, but I don't think you'll need it.

Read the plugs and you won't have to guess.

Please post your current cam specs so we can look them over.

-Mindgame

At first I thought he was mistaken on his numbers! Like MG said, post up those cam specs.

well my heads are lt1 castings that my cousin that owns the local speed shop had his porter work 40+ hours alone on just my heads.

they were cut on a bridgeport both intake and exhaust then ruffed in by hand. they got hand ported from there and equalized runner volume the flow numbers seemed low for how much work was done they were in the low 280's intake and low 230's exhaust with no pipe but he told me while the numbers meant something there were alot of the story they dont tell on what he did

they were milled to 50 cc and 2.02/1.60 race flow's new seats where put in and a comp valvejob was done with his secret backcut on the valve's for great low lift flow

The intake was milled to fit and ported the same way also opened up for the 58 mm tb its a lt1 also btw

the cam i ran last year was a cc306 on a 112 lsa but my problem is the lifter bores were grovved so i am switching to a solid roller plus i want it to be alot faster and i have no idea why i put in that cam in the first place i think i was worried about it being able to pass emmisions and get it tuned but i am exempt now and i know a solid roller is more than capable of being tuned with the stock computer

the car is missing the back seats,air cond.,power steering, smog stuff, abs, jack and spare tire and i am on draglites its a hardtop I dont know a real weight but i am trying to knock it down to the 3k-3200k range for weight

You are probalby going to need to run alcohol to get that thing to work.

Rich

"Stock" computer?

I don't mean to sound mean but I think you've went in the wrong direction with your build.

Static comps of ~15:1 indicate to me that the engine is built to make high rpm hp/tq. IMO, this one should be turning no less than 8k rpm. Aparantly, you need to rethink what it is you're trying to build.

Something alot of guys miss, I guess because most aren't drag engine guys is the confusion with the DCR and how it ties into the efficiency of the engine. You take a guy with a 450 ci drag-race small block running AFR 227 heads & cast intake with a 11.5:1 DCR vs a guy with a 330 cid motor and splayed valve heads running the same DCR. Who has the higher DCR near peak torque?

On another note.... take your 11.6:1 example and plug in VE's of 94% vs 106% & tell me where you're at.

Now, how I could run 122% VE on one of my drag engines and ~14.6:1 DCR with VP C21, while you're going to "need alcohol" is beyond me. Maybe someone can explain it to me.

-Mindgame

Easy killer! You know the Doc has been on a alcohol kick over the last year with his BBC.

What MG means buy the DCR here is the effective compression ratio. The Comp Elim style 330 cube motor has the higher peak cylinder pressures, so it has a higher effective compression ratio (VE% x DCR)

Bret

To start with he has NO cam at all with the 306. Like I figured and said in an earlier post it needed a bigger cam.
We have a fellow here that HAS a set up and really don't know which way to go. I am sure he doesn't need to be baffled by formulas and things he knows nothing about.
VE by itself don't win races and neither does efficiency,don't think he is on a fuel mileage kick either.
If he puts a bigger cam in it to make the 396 make some HP the DCR will go way down and the fuel won't be pump gas but 110 isn't out of the question.

I think it would run GOOD on alcohol and a blower with a little NO2 on top of that.
Ya would be hunting the heads in the next county after the first pass.

Re: alcohol remark. It was only about 20% serious, the rest was sarcasm. But it was based on the observation that I don't see many motors with 15:1 running gas, regardless of the VE. What I was trying to do was get this refocused a little. He needs to go back to the drawing board, IMHO.

MG: you seem a little touchy?

Rich

This gentlemen is not staying with the CC306... that's what he's saying in his post... that's why he's asking about solid roller lifters.

I've already stated my thoughts on what he's trying to do and where he's going wrong.

At some point you have to make a decision.... "Race car" or "Street car". Build a fast race car or a fast street car that sucks as a race car. If you have the money you can build a really fast street car that pulls double duty, but it's still not going to win you much money.

And no one's talking formulas, unless you consider multiplication of percentages a higher math. Just talking "understanding" of what's actually going on. And let's stop with the straw man arguements... no one is saying that any ONE thing is going to win races. I'm real cool until the patronizing starts up.

The guys who know this stuff win the races and the guys who don't.... don't. How someone could place so much emphasis on stretching head bolt studs and then write-off the importance of VE is a little confusing to me. But I'm starting to figure it out.

Rich,

"Touchy"..... yeah, maybe but I get that way sometime. Never anything personal on my part. Speaking of alcohol.........

-Mindgame

Maybe ya never had your a** handed to ya by a Vega with a "dump truck motor" with all the "wrong" s*** in it. Ya couldn't make that combo work on paper if ya life depended on it.
It's .030 over 454 with "to small heads" home ported a "flat tappet cam" big "domes" .100+ quinch, a dual plane, stock crank and rods and way to small carb(looks like a 700-750 vacuum secondary) on motor and runs mid 9's. It just runs... It has a junk yard glide and home made ladder bars and DR's.
This guy is no genus he just"happened" to put together a bunch of used stuff he bought or got around town and it flys for what it is.You figure it out.
Yea I don't care for TTY bolts like some folks,they are junk to me.

Never said VE wasn't important I said by itself it don't win races.

Exactly what I already said and know... let's rehash it a few hundred more times for good measure though.

and the beat goes on......

-Mindgame