Ceissus

iTrader: (4)

ok....a member on here is selling some 853 castings that were ported as follows:

Here are some TEA TF215's

Intake Exhaust
0.1 - 66 - 54
0.2 - 138 - 118
0.3 - 218 - 187
0.4 - 272 - 231
0.5 - 308 - 252
0.55 - 318 - 258
0.6 - 324 - 262

QUESTION:

1) how is it that these heads flow so much better than TF's from .100 through .400 lift???!

2) even though they flow this well at low lifts, would these heads still be inferior due to the less advanced design? i.e. valve angles, spark plug location, combustion chamber etc.

judging by flow a lone, these 853's seem to be superior being that most of your cam lobe duration is below .400 lift

what are your oppinions?

danf1000

iTrader: (2)

i am not a big fan of the whole dynamic compression thing...

it is my thought that flow numbers help set up the actual compression of an engine. and the amount of air that an engine can swallow through one cycle is a variable amount as a function of rpm.

that being said, a higher flowing head certainly could increase cylinder pressures and pose a situation where it highlights the problems of a less advanced or compromise design on the combustion chamber side. only one quench pad, less exhaust valve cooling, spark plug on the intake side, rough casting, etc........ could mean that your "dynamic compression" at that point of throttle position and rpm could lead to premature ignition.

just a few thoughts though. apologies if i am starting a squabble here....

Ceissus

iTrader: (4)

i thought DCR was a function of cylinder volume and valve timing alone....and not air mass.....

in which case flow numbers are irrelevant

i just don't see how the 853 numbers can be THAT much higher.

it's my thinking that more flow is good, no matter what? maybe i'm wrong?

but would it be better to get the TF heads which have less flow but a more advanced design?

/scratches head...

floman

iTrader: (54)

Something else you might consider is the port sizes. A bigger port will flow more air, but what is the velocity of that air going to be compared to a smaller port that flows just a little less. The higher velocity port will make for a more responsive engine and better power under the curve.

danf1000

iTrader: (2)

Exactly, Cessius, there lies my point. Then let's not call it "dynamic".

Brian Tooley Racing

iTrader: (13)

The low lift numbers on those heads are not realistic. Low lift flow is controlled by valve diameter and valve job. If this head still has a 45 degree seat then this head had a leak when it was flowed. The other thing to keep in mind is that a lot of flow at .100"-.200" can have negative effects on idle, drivability, fuel mileage and power output. The TFS heads actually have the .100"-.200" flow reduced as much as possible, this is why you see people comment on how great the idle is on a 500 RWHP 5.7 with TFS 215's on it.

If you would like to send me one I will flow it for free and ship it back for free.

Ceissus

iTrader: (4)

Thanks brian, this is exactly the information i was looking for.

brad8266

iTrader: (23)

You are completely mixing up airflow and compression ratio, 2 different thigns.

LS1curious

double posted.

LS1curious

That would be the primary disconnect that seems to go round these parts like the Flu. Imagine this scenario. Whats your DCR in a vacum ?

danf1000

iTrader: (2)

i mixed up airflow and compression ratio. thanks for the help