8POTS

Just after an opinion on the FAST LSX manifold on a 427 CID 'big banger'.

Is the thing capable of flowing sufficient air to a mill of this capacity?

I know that there is some meat there to port match and that the construction allows access for filler for shaping but does it flow enough to make power in the 2000-6000rpm band where it will be operating?

I have a port matched LS6 manifold but It doesn't seem to provide sufficient 'headroom' to let the thing breath.

Has anyone had a go with one in this application?

Anyone from FAST care to comment?

Thanks guys

11 Bravo

iTrader: (3)

No one knows yet, looks promising. They are supposed to be out about now, but when someone gives a timeframe for a new product, you can usually add a few months to that lol. The AFR heads were supposed to be out by christmas. They are nowhere to be found.

sr71bb

iTrader: (3)

The FAST MAY help. But more than likey you may need a larger throttle body that is capable of flowing more air. What heads are you using????

99 Black Bird T/A

iTrader: (4)

With the 427 I think you'll want the 90mm TB version of the LSX. Also since the LSX can have the runner floor removed so it's a big open penium, I think some variation of LSX will shine on your 427. However, I think the GMPP will have more potential than the LSX.

8POTS

Yeah, figured this might be the case...I have an 84mm Starr performance TB on there at the moment. Where can I find out more about the GMPP item?

I see FAST do a 90mm Tb for the LS1 too, which looks a quality Item.

As for the heads , they are flowing around 330 fpm on the intake and just over 250fpm on the exhaust at 28 inches of water / .550" lift. They have good airspeed so midrange power and torque isn't a problem. These are the original LS1 heads as opposed to LS6 Items.

The LS6 manifold is better than people give it credit for but with a motor moving this much air, it struggles and limits potential.

71CamaroLS1

Assuming they're both well designed, the GMPP will probably flow slightly better, and with shorter runners, will likely make more top end power. The FAST intake, with the long runner + plenum dual resonance design like the LS6, will almost certainly make much more torque below 5000. The intake design, IMO, is one of the real secrets of the LSx family engines - no way a 346 makes close to 500 ft-lb at the crank with a carbureted style intake. Notice that nice big hump in the torque curve around 4500 - 5000 on the dyno charts - that's the intake tuning working for you.

Of course, these comparisons are speculation until both of these intakes are out and available for real testing (not to mention, real aftermarket porting modifications).

99 Black Bird T/A

iTrader: (4)

Well around March maybe a little before, I might be able to answer what sort of torque curve the GMPP will make on the same set up as an LSX and LS1. We plan to do engine dyno testing on my new set up for the RS. I think I'll be able to share some of the data.

I would expect the GMPP to have peak torque later than the other two intakes and this should help with making more power up top.

8POTS

Thought I'd resurrect the LSX 90mm manifold discussion now to see how folks have been are going...particulary in a 427CID setup.

Still thinking hard about a manifold to stick on the beast. At the moment I'm running a 242/242 single pattern cam cam on 106LSA with lift around .580"/.580". Heads now flow just a whisker over 340CFM on the intake as opposed to the earlier figure of 330CFM

Peak power arrives at around 5,900 RPM with the stock fuel system (save for the 50lb Bosch injectors) and LS6 manifold.

Anyone had a chance to test out the LSX 90mm jobbie...how did you find it? worth the outlay?

J-Rod

I'd look at the Harrop 8 runner for your ride and Sam's SD tune. But, the FAST is much better than the LS6.

Jason99T/A

iTrader: (21)

A ported FAST 90mm intake and TB is worth ~15hp on some pretty aggressive 408+ci setups I have seen. It is definitely a worthwhile mod over a LS6 intake.

8POTS

Yeah...Ron Harrop makes some tasty kit. He's been having a few struggles with it though..been a flat spot they've been working on ironing out.

Just curious at this stage how the FAST 90mm job was treating people.

LOnSLO

iTrader: (15)

Why not just use the LS2 with a FAST 90 TB? That's what I have.