LS2Ttype

iTrader: (9)

Hello Im looking into a better more flowing intake

Right now i am running the stock LS6 intake with a 75mm Acufab throttle body

If i was to swap out the LS6 for a New 92 Fast and buy the Fast 4 to 3 blot adaptor spacer so i can reuse my Acufab throttle body how much power would i pick up and how much higher does a Fast rev compaired to the LS6

From what i hear the LS6 falls off around 6,200 rpm

HCI2000SS

iTrader: (2)

Are you running different heads or a cam?

LS2Ttype

iTrader: (9)

Yes , Ported 241 heads (300cfm) 215-230 blower cam and D1-sc @15 psi 740/660 RWHP and TQ

LS2Ttype

iTrader: (9)

any specs or back to back dyno runs swaping out a LS1/LS6 intake for a Fast 92?

99Bluz28

iTrader: (35)

I would use the CBM throttle body adapter, it's a better piece with a tapered opening.
http://store.custombuiltmotors.com/e...d-adapter.html
Here it is in a black finish:
http://galleryplus.ebayimg.com/ws/we.../1000x1000.jpg

itsslow98

iTrader: (18)

Using a smaller then stock throttle body on a bigger then stock intake manifold kinda defeats the purpose. Youre getting rid of one restriction and leaving the other. Do a 90mm TB minimum if you want to do a FAST.

LS2Ttype

iTrader: (9)

My tunner said my stock LS6 intake was giving up at around the 6,200 rpm on the dyno, nothing about the stock size throttle body, Im running a Acufabe its a tiny bit bigger that the stock 75 which i measure at 74mm and the acufab is around 76 which is the exact measurement of a LS6 intake, either way i dont think the throtle body is the problem , with the D1-sc blowing threw it , it shouldnt be to restrictive, it sounded like the ports in the intake couldnt keep up with the heads, but i really dont know for sure

LS2Ttype

iTrader: (9)

99BluZ28 are u running that intake/throttle body spacer?? i know fast makes one also, its for the same reason to mate up a 75mm LS1 3 bolt throttle body to a 90mm 4 bolt intake, Pretty cool option

Exidous

iTrader: (11)

FI certainly makes the need for an intake less necessary until you get up there in power.

I know folks have made some crazy power with the LS6 intake but it will still going to be a restriction at those power levels. What size tubing are you using? If your cold side is 3" then I see no reason to go any bigger than 75-85mm on the TB. Personally I think you would see a gain. With heads openend up like that, an intake certainly wouldn't hurt. I bet you'd gain more than any stock to fast N/A swap.

I'd just look at getting a Professional Products 85mm TB with the FAST 92. The FAST 92mm intake does have the ability to bolt up a 3-bolt TB. It just doesnt have threads so you'll have to use a nut and bolt.

LS2Ttype

iTrader: (9)

Thanks for the input EXidous and i agree, im running a D1-sc threw the bigger 4.5 twin intercoolers, the ones that come in the F-body LS1 kit are very small there only like 3" thick the upgarded ones i have are thick 4.5" and they flow about 700+ cfm each so they do match the D1-sc max cfm rating (1400) cfm, The Piping is all Procharger 2.5" tubing, To a Metal air plenum under the hood, if your familiar with the LS1 Procharger set up the twin intercoolers direct air to the plenum on both sides of it and then there is a 4"
oval outlet that i run a 4" to 3.5 SLP rubber bellow couplers to the throttle body
I know there is a lot going one here to get the boost to the motor but it works quite well

And the Dyno graft showed her peaking in power and falling off at around 6,200rpm, The blower would still keep going and make more boost with more rpm but it looks like shes not wanting it, So even if i pulley it up and make more boost i think she will still Peak at the 6,200 mark but make more power at that mark because of more boost/fuel etc, I was thinking it was maybe my cam but acording to my cam spec guy she can pull way past 6,200 with the cam i have, and when i asked my tuner at the time Y the drop off at 6,200 the first word out of his mouth was "intake manifold"

99Bluz28

iTrader: (35)

No, I'm not running one.
I would have to think that the flow into the intake would be smoother/less turbulent using the CBM, compared to the FAST adapter.

Exidous

iTrader: (11)

Falling off at 6200 on a P/C motor makes me think valve train more than anything. An intake would taper as flow increases not just fall off.

Possible instability in the valve train. What's the setup? If it's all stock the valve could be floating due to the pressure on it from the P/C.

Another thought.......try taking the P/C elbow off. The P/C may be choking. What does the MAP look like at 6200RPM?

PS. I know quite a few folks that are running to 6800+ at over 1000whp with the LS6 intake.

dr_whigham

iTrader: (49)

What's the exhaust set up?

LS2Ttype

iTrader: (9)

No valve train is good, double springs, titanium retainers, light weight one piece ferria race valves, Geff's 215/230 .600 117+2 blower cam, comp Hi-tech pushrods, LS7 lifters, stock rockers with felcrum bearning up grade, I covered this motor to a T.

exhaust is well thats another story: FLP (finish line performance) Long tube headers, Headers look good and flow pretty good by tests i have seen, But the Y pipe is only 2.5" but fits very well under the car, at the time all other header/Y pipe set ups for 98-02 F bodys didnt fit to good, Anyway i running the FLP test pipes (no cats) and all of that is going to the Stock SS slp duel/duel exhaust, I know others that have went to true duel exhaust and redynowed and picked up 50-70 HP on FI LS cars. But mine sound so clean, no raspy loud drown , so i wanted to keep her stock sounding which she does

Ill have to look at the dyno graft again maybe she didnt fall off as bad as im saying, but at the time i did question Y she stoped pulling, and my Tunner first word was "intake" he didnt say anything about the cam being to small or the valve train floating or the exhaust being restrictive, which it is! I know i would pick up some good power going with american racing's duel exhaust set up and headers But $4K later No thanks!

dr_whigham

iTrader: (49)

I personally don't think it's your intake. Too many folks running A&A or ECS kits that prove that with stock intakes and throttle bodies.

It is ABSOLUTELY your exhaust.

LS2Ttype

iTrader: (9)

since i cant figure out how to sen pictures to my E-mail threw my new phone ill post up what my Dyno results were

RPM HP TQ Boost

4000 454 596 7.5
4100 474 607 7.8
4200 493 616 8.2
4300 513 626 8.5
4400 534 638 8.8
4500 556 649 9.1
4600 577 659 9.4
4700 595 665 9.7
*4800 609 667 10.0
4900 622 666.8 10.4
5000 634 666.4 10.7
5100 647 666.6 11.0
5200 659 666.7 11.2
5300 672 666.1 11.5
5400 683 664.5 11.8
5500 694 662.5 12.1
5600 705 661.3 12.4
5700 716 659.6 12.7
5800 725 656.7 12.9
5900 732 652.3 13.2
6000 737 645.5 13.5
*6100 739 636.9 13.7
6200 738 625.7 13.9
6300 734 612.6 14.2
6400 728 597.5 14.5
6500 708 572.1 14.8
6600 609 484.6 15.0

Exidous

iTrader: (11)

That's a pretty hard drop for an exhaust restriction. How smooth is the curve up top. Any ripples?

itsslow98

iTrader: (18)

Belt slip?

Exidous

iTrader: (11)

I'd say that's possible but the boost was still increasing with RPM.

LS2Ttype

iTrader: (9)

No Boost slip , im running Asters Auto spring tentioner system, and right boost was still increasing

Now when you say a hard drop at what RPM tp RPM are you talking about?

dont go by 6,500 to 6,600 because the Rev limmiter was set to 6,600 and he let off

But from 6,100 (where she peaked) to 6,500 she was falling and the boost was still increasing