It's also about the components within the heads, i.e. springs, valves, retainers etc......

It's not just about flow. Which reminds me. Jsup thought he would make 600chp on the high end with his 427 build. I am no expert. But if a head flowed roughly 270-275 cfm at it's peak. I dont know how it could possible make 600chp? Wouldn't that need a head that flows closer to 310cfm? Which means if 600chp was his goal, he picked the wrong cylinder head!

If I am way off then cool! I will admit it at least.........



http://forums.corvetteforum.com/show...post1567310020

Can you guys check out the above link. Hoping Jsup doesnt ruin it.

 

Apparently this thread is going nowhere. Unless I hear from the op, this will remain locked.

EDIT: Per op's request I will re-open this thread with the understanding if the bickering continues some time off will be issued to those who continue the personal attacks. Let's try and keep it civil and on track.

 

Thank you

 

I'm used to my present set up and I'm only running up to 5500-6000 RPM. What should I expect a 383 to rev up to?
My bottom end will have -12cc dished pistons, since thats what coming in the Eagle kit. It claims it will have 9.9 compression wit 64cc heads. I don't want to run out of power by using a larger head.

 

That's pretty low comp for a NA engine.

 

Well you're not going to run out of power due to the head being too large; you would find that the engine was sacrificing power off its peak without seeing any gain on the peak number. For reference, a good 410 cubic inch sprint car engine will turn 8500+ RPM race after race, a Nextel Cup engine will hit 9200+ RPM but remember they have a reduced stroke that helps them cope a little bit.

I really need to get an idea of where you want the bulk of the power to be made; if it's in the 4000-6000 arena you would be better served with the mcsa (minimum cross sectional area) of a standard port 200-215cc head (again this is to make peak power at 5800-6000 with the increased airflow requirements of the 383).You also need to determine if the intake you have will allow the engine to make good power up there; what kind of RPM are the other two engines turning? A dyno sheet that would allow us to get a feel for what the intake can do would be useful. Also, if you run an iron head you could get by with a little more compression, 10.3-1 would be a nice number; aluminum could get you to almost 11 without any problems... Also, what type of cam are you planning on running? Do you already have one or will you be choosing one? We really could use a little more information about the usage before we can make a good recommendation.

 

Jsup, actually, just so its clear, I am not saying they are both basically the same, I personally believe the AFR 190-210 cylinder head selections are better than Dart's line-up for the majority of C4 street/strip set-ups that are very common here on this forum. I believe, in most applications, the AFR cylinder head would consistently make more power and et better than the similar sized/priced Dart cylinder head as seen in your example.

But, that is not to say I think the Dart cylinder head is a bad cylinder head, I don't, I think its actually overall pretty good, its just that I think with the new Eliminator series from AFR, they have pushed themselves ahead of the competition. I do expect Dart and/or Brodix and others to catch-up sooner or later..... nature of business and a wonderful by-product of business for us the racer..... cylinder head manufacturers competing with one another can only be good for us.

But, thats just my opinion, I've got no problem with differing opinions, and I know I very well could be wrong..... but for now, my recommendation for most would be the AFR cylinder head.

talk to you later
Beach Bum

 

I guess I don't follow. You are the one building a "stroker 393 LT1 with a set of AFR Eliminator Comp Port 196's"? If not, how do your priorities or your wife have any bearing?

You said the car will make amazing power and will be more proof the power is in the heads. I'm asking how you can say that if it's not built yet? Presumably your answer to that is not "I'm using quality parts, and my wife is knocked up".

Really there's probably no answer you're gonna give that will be satisfying, so I'm not sure why I'm bothering following up with this... I guess I still have hope you'll make some kind of rational point. If not, best of luck with the build and the new kid, sounds like a lot to look forward to.

 

12 cc dish on a 383's 3.75 inch stroke will be closer to 10.25 to 1 which isnt bad for a street car but with good chamber design on a aluminum head you can get 11 to 1 to work just fine as Deakins says here. Thats what i have, 11 to 1 and its great, no problems at all with 92-93 octane fuel. I think it will run on 89-91 but i didnt try yet. Keeping 93 atleast for the nitrous

I agree tho we need to know the rpm ranges the xram will support. I know NOTHING of that intake. I'm a TPI/MINIRAM/Superram/HSR guy. Looking at the xram.com website i see they say 250cfm per runner out the box which is healthy but they say there are many producing over 320whp which is pretty weak in a sense as there are many TPI setups doing over that with a 383. Superam even more hp

SO i would think the rpm range on this intake is comparable to TPI and should make most power between 4500-5500 rpms on that 383. So a relatively smaller duration cam would be nice to have and you dont need super high flowing heads or big cc port heads to achieve that range. Any decent 190-200 cc head will fit the bill just fine. Some cam with around 224 or so degrees duration on the intake and add 4-8 degree split on the exhaust should be fine with that setup. 320-340whp with decent heads. with that small cam you dont want to high compression as you will not beable to keep dynamic compression down so there goes the pump gas. 10.25 to 1 compression and a medium cam like that should be great for that motor

 

Bob. What question do you want me to answer?

 

I came up with the comp ratio of 9.9 from eagles website.
http://www.eaglerod.com/products/Che...ssemblies.html


I thought I had answered this before but maybe not.

X–CELerator SERIES: 360 degree, single–plane, open plenum Manifold designed primarily for high–performance
street, drag, marine and oval track use. With an effective rpm range of 2000 to 6800

Since this is the base used I'm assuming these are the RPM ranges

As far as a dyno sheet, the only one I have is when it was installed on a stock motor. This was before I changed my heads and cam the first time. If you'd like to see it, its in my corvette photos of my profile.
Hope this helps... My goals are realistic I believe... its just a matter of knowing how to get there

 

I agree 100% here, the timeslip matters, different dynos will give different results, but the 1/4 mile will let you know exactly what kind of power you are making.

MPH in the 1/4 Mile is the true indicator.

Vic

 

This thread has gotten over a hundred replies and more than a thousand views and I can't believe NONE of the cfi guys have not chimed in at all. Well one did (thanks). I'm not the only one here with the Xram. So any of you guys that just may be lurking feel free to jump in.

 

If that's rich. What's this? Yup this is John for you! http://www.corvette-guru.com/modules...d=5460&start=0


To the orginal poster, Did u decide your combo?

 

if that manifold can indeed support that rpm range and can give the fuel requirements to support that power then there should be alot of CFI guys doing some good numbers/times. I just havent seen any which doesnt mean they dont exist... just means it isnt as popular thats for sure

 

Its actually even more than that.... the timeslip is just a print out of the history you created a minute earlier. I personally want acceleration..... which as you know very well, is as much about optimizing the power you have, whatever that is, as making HP is.

 

I pretty much agree, I haven't seen much of the X-ram, but haven't been looking either, so maybe they're their. But, for what I have noticed, most of the very strong running 84's I have seen at the track were running carb.

I think it would be interesting to see a strong running X-ram..... hope you complete your build !! Good Luck !!

 

Where is CFI-EFI!!!!!!

Race On!

 

I am determined to build this, this winter using the X-ram. I refuse to go carb! I'm gonna have to call them and pinned them down for some real numbers on this intake.

I to thought for sure CFI-EFI would chime in as well

 

Did a few minutes of searching, and i've seen only 1 383 xram setup and it went 12.48 at 111.6 or so in a 84 vette. Not all that impressive for a 383. I dont know his setup but thats all i found

MOST of these guys i've seen are using small cams and these builds are similar to other TBI builds.They are not rev happy motors so i'd call the x-ram ppl to see what they say. I'm not sure these intakes will support the high rpms