Corey_68

I'm looking for flow #'s on stock GM iron rectangle port heads, 2.19/1.88.

Can anyone help? :confused:

:cheers:

69ttop502

Here you go Cory. This is off the Chevy High Performance spreadsheet with all the heads on it.

.100 68
.200 129
.300 188
.400 233
.500 259
.600 291
.700 313

These were the #188 heads but the 990 were almost exactly the same and was done on a 4.250 bore fixture. Bill.

Corey_68

Did they list exhaust #'s?

:cheers:


[Modified by Corey 68, 11:22 AM 3/16/2003]

69ttop502

Oops forgot, sorry. Here they are Cory.

.100 45
.200 90
.300 131
.400 170
.500 188
.600 195
.700 200
.800 202


Average flow intake 247
Average flow exhaust 168 for a I/E ratio of 68%

Corey_68

Awesome man,

Thanks :cheers:

bence13_33

I too was looking into a set of "990" or "188".

"188"

.100- 68/45
.200- 129/90
.300- 188/131
.400- 233/170
.500- 259/188
.600- 291/195
.700- 313/200

"990"

.100- 69/53
.200- 125/103
.300- 183/140
.400- 233/176
.500- 264/198
.600- 292/204

The "990" heads are no longer offered. The "188" heads are the service replacement head. As you can see the "990" heads flow slightly better than the "188s" but the "990" heads don't flow to .700 lift. The exhaust flow numbers are the weakest asset of these heads. It wouldn't take much to get the flow numbers on the intake into the 315 range. However, ideally you would want the exhaust flow numbers around 250 or so.

These heads also have plenty of room to accomodate a 2.25 intake valve.

Corey_68

I ran the DD2000 using these flow numbers and I'm really disappointed. First time I didn't use the flow numbers and let the dyno pick the numbers. Then I ran the with the flow numbers and the the power dropped BIG time. It showed the engine is dead by 5,500 rpms!!?? :confused:

I didn't plug in pressure drop.

When I didn't plug in the flow numbers I got 593hp@6.5K and 564tq@4.5K

With the flow numbers I got 508hp@5.5K and 502tq@4K
I'm using the CC 294S (348/248 .595/.595) This cam is supposed to pull to 6,500.

Set up:

454 H.O. +.060 forged pistons
stock forged 7/16 rods
10:1
G.M. Iron 325cfm heads 2.19/1.88
294S
Demon 850
G.M. H.O. alum. dual plane (center divider cut)
Hooker Side mounts

What am I doing wrong. :confused:


[Modified by Corey 68, 2:14 PM 3/16/2003]

Les

Those heads flow just fine above 5500(and well above your cam lift specs) & your cam should pull strong to 6500+ RPMs- looks like a glitch in DD2000 to me.

bence13_33

Corey:
I noticed the same whenever I was contemplating useing the "990" heads. I'm not sure what to tell you. By far the weakest point of the head is the exhaust ports....this is primarily where the horsepower is made (all other things being equal).

69ttop502

Corey, I would tend to agree with Les and Bence. There are plenty of guys running in the 9's with those heads with just a 3 angle valve job. I sold my 188's on Ebay and I have kept in touch with the guy that bought them and he ran 990's in a heavy Monte Carlo to 130mph trap speeds with just bowl work and valve job in a 454. I think 427HotRod ran 120+ traps with iron oval ports if I remember correctly.

Corey_68

That's good to know fellas.

Shane, when are you going to get that rat on the dyno?? :D


Thanks again for the reassurance guys. :cheers:

bence13_33

Corey:
I need to find a dyno around my area, I'd also like to find a couple guys to go with me. For now the money goes towards go fast goodies :) .