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FAST FAST™ LSXR™ 102mm Intake Manifold For LS1/6 Engines

8K views 34 replies 11 participants last post by  crankedupforit 
#1 ·
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The engineers at FAST™ teamed up with the airflow specialists at RHS™ to develop a three-piece, polymer intake manifold for cathedral port GM LS1 engines. The new LSXR™ 102mm Intake Manifold for LS1 Engines offers all of the modular advantages of removable runners, while achieving modest gains in performance over the already proven original LSX™ design.

Building upon the performance legacy of the original FAST™ LSX™ Gen III Manifold, the new LSXR™ 102mm Intake Manifold features a three-piece modular design that allows easy disassembly and porting. Extensive testing led to a runner design that is longer and less restrictive, yielding both torque and power gains over the stock intake. New to this design is the ability to remove individual runners from the manifold for modification.

The LSXR™ is constructed from a proprietary advanced polymer material which offers a host of benefits over aluminum aftermarket intakes, including lighter weight, strength and improved heat dissipating characteristics. While the LSXR™ features a 102mm air inlet that is perfectly suited for the FAST™ Big Mouth 102mm Throttle Body™, it can also be used with stock or aftermarket 90mm or 92mm throttle bodies. Other features include integrated nitrous bungs and perfect bolt-on fitment that allows the use of factory accessories without modification or clearance concerns.

Features & Benefits:
• 102mm intake manifold designed for LS1/2/6 cathedral port applications
• Modest performance gains over original LSX™ intake design
• Advanced polymer material is strong, lightweight, easy to modify and keeps intake charge cool for power enhancement
• Works with 90, 92 or 102mm bodies for high flow with a minimum of restriction
• Retains all factory fitments and under-hood clearance requirements
 
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#10 ·
Id like to see what gains a cam only cts-v would get from a 102.

Someone buy it.

I plan on buying one but I dont see it happening till at least the fall :helpless:
I got 15 on a cam only LS6 going to 90mmTB on a TPIS/LS6 90. I assume the 102 would do at least that. With your cam, and your headers I think (but do not know) that the gains would be significant.
 
#14 ·
We have not been able to get one on a CTS V so I do not have specific V numbers but these have been on GTOs, F-bods, trucks/LS3 (different part number for the ports).
And like I said, it depends on the mods as to how much this intake picks up.
The FAST 90/92 has shown 15-25 on a bolt on car and more than that with a Heads/Cam car.

Russ's LS1 GTO M6 with bolt ons picked up 15+ with intake and TB and he has Headers, CAI, Catback, UD pulley. Later added Ai 241 CNC'd heads with rockers and pulled 420ish.
Jeff G's LS2 GTO A4 with bolt ons and Ai 243 heads/FTI Tiger Shark cam with a FAST 90 stock 90mm ported TB made 480, put back on a ported LS2 intake and put down 450.

These are local cars. FAST will no longer be making the 90/92 intake therefore the 102 is the only option but it will show the same gains.
 
#17 ·
My experience with the Fast 90 (although it is ported), on a nearly full bolt-on (no EWP, or UD balancer at that time) LS6 (stock heads and cam) with a nick williams 90mm TB was +10 hp, and lost a some TQ.

The unfortunate thing was under 5500 rpm's I lost HP and TQ from before.

+9 peak rwhp
-3 peak rwtq
-9 average HP
-4 average TQ



Now with that said, I did note that F.A.S.T. indicated that they redesigned the 102 for better lower RPM TQ.

Here is my writeup on my fast90 mod. Please keep in mind that I did this in prep for a cam upgrade (and eventually premium heads).

http://www.cadillacforums.com/forum...-general/124436-stock-head-cam-346-ls6-w.html

I am glad I have my FAST, I just wanted to set the proper expectations. This is definately a gateway mod (kinda like headers), if you get this you will end up with a cam or heads and cam :D

-Chris
 
#22 ·
Shon,

I was interested in their comments about making the runners longer to increase lower end torque. If they really improved that, then results from the 102 may be better than the 90, and it might not be as much of a 'only do it if you are cracking the engine' type of a mod.

I guess they get bonus points too for making the whole so big you can stick your hand into the engine now.

-Chris
 
#20 ·
Did the mod bug bite? Or you got tired of a boring lope at idle?
 
#23 ·
This is not an easy swap.

Beside the obvious:
-Intake
-T/B
-Adapter

You will also need the gaskets and the fuel rail adapters.

Even with a stock 90mm LS2 T/B you are going to need around $1400 to make this happen. I have been researching this for over 2 days (and not getting a lot of work done) trying to locate and plan the best price/set-up.

With the minimal gains that have been shown over the 92 to the 102 there have not been a large amount defecting to the new intake. That is driving the price of the used 90/92 up and since FAST has decided not to make them anymore, the price for a new 102 is comparable to the price of a used 92.

So where does that leave us? The Gen III LS guys are in tough spot right now. So as I continue to search if I happen to see anything I will let you know.

Shon,

Thank you for your diggin and the PMs. I have still not ruled this out yet, as I am going to need somthing better for the 383. In the meantime I am wrestling with the $/hp equation, and how much do I want to piss off the wife.
 
#24 ·
but you're just speaking of the LS6s right? On an LS2 you can pop this intake on and retain stock TB and all, right? LS6 guys have to face all the adapter/TB/misc stuff to make it work...I think.
 
#29 · (Edited)
Interesting test data in a book out called "Dyno-proven GM LS1 thru LS7 performance parts". Section called 90mm LS2 vs. 78 and 90-mm LSX intakes.
Test motor was an LS2 with a COMP XR265HR cam and a set of Hookers. Numbers are bhp.

90-mm LS2 intake: 485 hp @6000rpm
78-mm LSX intake: 500 hp @6100rpm (largest gain 23hp @ 6500rpm)
90-mm LSX intake: 500 hp @6100rpm (largest gain 20hp @ 6500rpm)

Doesn't look like TB size has any impact on this LS2 with a LSX intake. Infact the 78mm flows slightly better below 4000rpm according to the dyno sheet. Hmmmmm..........
 
#30 ·
Interesting test data in a book out called "Dyno-proven GM LS1 thru LS7 performance parts". Section called 90mm LS2 vs. 78 and 90-mm LSX intakes.
Test motor was an LS2 with a COMP XR265HR cam and a set of Hookers.

90-mm LS2 intake: 485 hp @6000rpm
78-mm LSX intake: 500 hp @6100rpm (largest gain 23hp @ 6500rpm)
90-mm LSX intake: 500 hp @6100rpm (largest gain 20hp @ 6500rpm)

Doesn't look like TB size has any impact on this LS2 with a LSX intake. Infact the 78mm flows slightly better below 4000rpm according to the dyno sheet. Hmmmmm..........
I guess that is because the 78mm maintains higher velocity. Just to make sure I understand, what is the "X" in LSX intake? (ie LS6 or F.A.S.T. intakes)
 
#31 · (Edited)
I'm just guessing here but I'd say the X means it fits any LS motor 1-6-2-7. The LSXR may be the version for up to the 102mm TB. A 78 wont fit on a LSXR I think. The point being however, is there a benefit of even using a 90mm with any FAST manifold on a LS6?? I could see it with an LS2 because the engine comes with one. Why not find a LSX and use the 78 you have for a LS6?

I think the evolution of the product went like this: Maybe Shon can help us out on this.

FAST 78 (use 78 only).
FAST 90 (use 78 or 90)
FAST LSX (use 78 or 90)
FAST LSXR ( 90 or 102)

The LS6 guys are pissed because they have to go with a 90 if the only FAST intake they will be making will be the LSXR.
 
#33 ·
LSX is for all the LS models. The R is for the trucks from what I can tell....
and the 102mm opening is the only option now unless you find a used one.
And the LS1/6 guys will have to use a slew more parts for this intake. ;-(
We have seen power from the 90mm intake swap on a stock 346. will the 102 show the same or more, not sure but it's an expensive swap unless you are LS2/3.
 
#34 ·
My question as to the "X" was really more specific to the test results you gave. Those results compare an LS2 intake with two "LSX" intake manifolds. Are the two "LSX" intake manifolds FAST intakes or LS6 intakes?

On the 78mm throttle body, I picked up 15 hp going from a 78 to a 90mm - both on LS6 intake manifolds, but I have a cam. I think a stone stock LS6 would gain little or nothing with a move from 78 to 90mm.

On a FAST intake I do not know whether I would gain with a 90mm over 78 or not. Since the bigger intakes are a big plenum chamber the TB size could well be less relevant.
 
#35 ·
The LSX is a FAST intake

I agree that going to a 90 on a stock LS6 wouldn't give you much gain.

I think your also right about a 78 on a FAST. A 90 may help with a set of heads.
 
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