Mindgame

Don't see the irrelevancy. Maybe when you're getting subpar CNC ports for all the money spent, but I'm not just talking LT stuff... talking performance in general.

When you say 'measure', what do you mean by that? From what I know of ports, they are 'surfaces' which can only be measured accurately via CMM or some other expensive piece of equipment. Using a gage would only get you a ballpark similiarity to the master port the gage was made from right?
As for who you work 'with', I didn't ask. Besides, it's not like we're giving away military secrets here... ahem, C£¡ñt@N..... BTW give me a hint at some of these 'front of the pack' guys you all are supplying. NASCAR? They're all using (hand finished) CNC heads.. Richard Childress, Chapman, Hendricks, Weld Tech, the list goes on.
Thanks!

-Mindgame

Ai

Believe me, dont believe me.. whaddever, but it doesnt make a whole hell of alot of difference. As far as subpar, well Weld-Tech, M2 etc, aren't what I'd call subpar. I know theyre using hand finished cnc stuff... alot of GPtech stuff from weld tech, but thats the point.. you said it yourself.. hand finished. If we get a gptech head that peaks around 381... & even though the port is a lil on the large side, end up gaining over 15cfm up top by hand, I dont care if it isnt as consistent as it was off the machine, it's going to make more power. If you're choosing heads you have to choose.. do you want CNC stuff that wont perform as well as hand ported, but will be more consistent than you need, or do you want to go fast. The gains from pushing a casting by hand are going to greatly outweigh the gains from having something that's more consistent than youll ever need IMO. Hell.. with freaky pressure wave interactions & the science behind manifolds, I dont think it matters all that much. I've ran a Zeiss Contura bridge type CMM & digitized ports before, so i am familiar with processes & capabilities, but... big deal, for anything this side of Formula1, meticulous hand porting is more than most people need, and with the core shift of production castings, will outperform CNC stuff every time. Can't mention who runs what, but.. yes.. some nascar... arca.. transam...allpro... *shrug* Thats stuff most people dont even realize exists though. Your welcome =P

scoobie30th

I was doing a search and came across this thread, i have the scoggin dickey catalog with these heads and the first advertised flow numbers are no where near what the catalog says. And these are the 2nd Version LT4 CNC heads as stated. You can find them on Page 47 and here is what it says.

LT4 Fully CNC Ported Version 2 - New !

Full port flow figures @ 28' H20
LT4 CNC Ported Version 2 -SD3287

Intake Exhaust
.100 65 49
.200 128 111
.300 184 141
.400 230 170
.500 261 178
.600 262 182

So there you go, no bull**** straight out of the catalog. Priced at 1082.50 per head.

SABLT194

Are Nascar head casting patterns and cores set up so that there is additional machine stock in the ports and chambers to insure full cleanup on the CNC? It seems logical that a fully machined CNC port that is hand finished is the best of both worlds. Cost vs Performance. I would imagine that the Digitizing resolution and CNC Cusp height allowance is a trade off of time vs surface finish as well so not all CNC programs are the same.

Great discussion guys!

Steve

Dr.Mudge

Ouch. So what your saying is, we can spend less and get more by avoiding these heads, whew.

Mr. Horsepower

Yes, most "NASCAR" type heads are cast very small (195 cc) and may then be ported to some 280 ccs. That gives a great deal of flexability in the port design although it is not imperative that all surface be machined. Most heads cast close to final size will likely show no sign of runner cleanup along the port floor until the area of the short side radius. No worries.
And yea again, the cusp height is all about program execution time. Our machines cut at an rpm of 30,000 which makes quick work of a cylinder port. Surface finishes are better, cusp heights are smaller and prgram execution time is still less than most due to the rpm of our machines. Most are still working with 10-15,000 and are on a much more "production" oriented scheduling. That plays a big part as you suggested.

Take care

scoobie30th

Have any of you headporters gotten ahold of the TEA heads and flowed them yourselves? The exhaust #'s on those are very high?

???

NightTrain66

TEA heads are VERY nice, they have good flowing valve job and ALL of the machine work looks good as well.

There was a post in the "advanced tech" section a few weeks back that talked about the exhaust flow #'s a little bit.