WizeAss

iTrader: (5)

had a nice discussion last night about its limits.... anyone have any feedback on its numbers?

if my heads flow 360ish.... but the intake only does 280... what good is it??

edit: found some info after the fact from someone who posted a link later in this post....

.500 319 225 71% 289
.550 332 227 68% 299
.600 340 231 68% 306
.650 340 235 69% 311

so 311cfm thru the stock L76 intake at .650 lift on stock heads...... not too shabby... the point is according to this fellas bench (which should have the flow of the heads closer to 330, you are only losing 30cfm from the intake)

Like Patrick said... get those heads to 360ish and you should get more flow thru that intake. especially down in the .300 - .550 flow range where stock heads do not even meet the fax flow of the intake....the more you raise the peak numbers of the heads the more you will see down in the lower lift areas.

Richard@WCCH

iTrader: (3)

Last year I posted some flow results of a stock LS7 head and an unported intake manifold. Do a search and I'll bet you'll find what your looking for. If you don't find it let me know and I'll se if I can dig up the test again.

Richard

blown2kss

wasn't he talking about the l76 intake the the ls7

Richard@WCCH

iTrader: (3)

Sorry. I meant to type L76. Here's the link:
https://ls1tech.com/forums/generation-iv-external-engine/602115-l76-intake-manifold-flow-results.html

Richard

Patrick G

iTrader: (14)

Wow, I didn't realize the L76 intake knocked the head flow down by around 30 numbers at .500" lift and above. A good flowing cathedral port head with a stock FAST 90 bolted up flows as much.

fast98

iTrader: (16)

ya but its also way less in price

WizeAss

iTrader: (5)

CAN THE L76 BE PORTED TO IMPROVE FLOW?

Patrick G

iTrader: (14)

My point is, many people are ditching their cathedral ported heads/FAST 90 intake for the L92/L76 combo. The problem is, there haven't been any large gains. So if you're starting from scratch, the L92/L76 is a cost-worthy option, but if you already have a good flowing set of cathedral port heads and a ported FAST 90, you may go faster by sticking with the "old stuff".

BlackHawk T/A

iTrader: (3)

GMPP took a stock LS2, changed the heads and intake to L92/L76 and gained 44hp.

FRDnemesis

iTrader: (19)

This is an awesome observation, which puts me at a cross-road since I have a real good set of LS6 heads and a FAST 90/90.

Mr.MartyStone

iTrader: (12)

I believe in another post Richard had, he flowed a ported 90/90 and AFR setup against a stock L92/L76 and it outflowed the 90/90 stuff by about 10 cfm at .500, and kept going up from there as the 90/90 setup stopped flowing around 288 cfm and went static.

Marty

Quik

iTrader: (7)

all you got to say, not to shabby at all for stock production parts!!!

1bigcam

iTrader: (9)

what can be pick up in a ported l76 over a stock one?

Richard@WCCH

iTrader: (3)

I thought I remembered posting that comparison. Read post #16 in the link I put up. I'll get some ported L92/L76 head/intake data posted up real soon. Patrick makes a very good point about upgrading to the L92's from aftermarket big breathing heads with FAST 90 intakes. The L92's really need some intake manifold manufacturers to get off their asses and build some suitable intakes for high power, high rpm engines. Waiting 5 or 6 years after the heads are out is a bit slow IMO.

Richard

427

iTrader: (3)

Have you run the "carb" style intake that GM has? Is it even released?
I have been running some engine dyno testing with the L92 heads and they are very good for the money, but we are getting some high vac in the intake at high rpm. I am going to run a ported set today.

Kurt

Stang's Bane

iTrader: (22)

I think we need to look at this as a more general question.

Intake flow being the same does it do any good to increase head flow?

Patrick G

iTrader: (14)

Absolutely! NASCAR engine builders found this out with restrictor plate motors. The better the flow and airspeed they got through the heads, the stronger the draw through the restricted intake manifold. We proved this for years when running ported heads with crappy LS1 (before LS6) intake manifolds.

WizeAss

iTrader: (5)

the simpliest theories can easily be explained.... good analogy. Thanks

Still.... at what point does the additional expense in head work become moot?

330cfm heads and a 300cfm intake?
360 intake heads and 300cfm intake?
400cfm heads and 300 cfm intake?

how much is it worth going from 330cfm heads to 365cfm??

Stang's Bane

iTrader: (22)

Very good points. I guess my next question would be: At what point would airspeed become to high, that it detaches from the cylinder walls? Different from head to head?

As forteen3gt stated would this be a law of diminishing returns type thing??

76TALS1

Here is another link with flow numbers. The L76 intake will flow over 320cfm
if your heads flow 360cfm. www.notasponsor.com

Tony