whitedevil

iTrader: (9)

I have been researching this do death, and trying to decide the best intake manifold for my built 408ci.


here is some info on my set up currently, and would like some input in what direction to go in...



Motor is a tsp 408ci 9.5:1, prc stg 2.5 ls6 heads, cam is 232/240, .595/.609, 115LSA, 112ICL. 4l60e and 3500 stall

I originally intended on boosting my car, however, funds are too limited, and plan switched to N20 at least for a season or so.

Car is speed density tuned, and running an ls6 intake manifold, and stock tb, a combo I was going to keep with forced induction.


I want the most out of my motor n/a, will likely be switching do a more n/a oriented cam, and need some real world suggestions. I have found gobbs of info about manifold and tb choices for forced induction, but no clear cut opinions on the best n/a suited manifold would be for my 408.

Sales4@Texas-Speed

iTrader: (4)

If the car spends most of its time on the street I would put a FAST 102mm intake manifold with a 102mm throttle body. It will provide the best power and drivability for a street car in my opinion.

whitedevil

iTrader: (9)

Thanks for the input. This whole combo I am running on is straight from you guys. What are your thoughts on my current cam and the addition of nitrous?

The motor runs very well even n/a right now. it is a true street car, and will see the track regularly, however, it is driven to work every day.

Longrodlx

iTrader: (1)

Just keep the LS6 intake. Wow you might gain 5rwhp from the fast 102 and TB. $1300 for 5rwhp does not sound like anything I would waste my money on. LS6 intake is one of the best factory intakes.

Burken01

iTrader: (88)

you'll gain more than 5 hp

More like 12-20

HISS

iTrader: (52)

FAST would be my choice. It's already gonna be kinda soggy with that c/r anyway. It'll need the extra tq.

geazowksitn

Wow you might gain 5rwhp from the fast 102 and TB

HCI2000SS

iTrader: (2)

Yes the gain will be more like 15-20 on that setup with a Fast

redbird555

iTrader: (14)

Care to share what brings you to this conclusion? Lol its a 408 not a bolt on ls1. Gains with a 102/102 would be 15-20 easy on that setup and probably another 5-10 if its got a good port job.

Op I agree though I would maximize your cam choice for good tq even if it costs you a little power up top. If possible I would rip off the heads and try to raise compression a bit by using a thinner gasket or decking the heads if you have the room.

Longrodlx

iTrader: (1)

Show me 2 Dyno graphs with a street 408ci stroker engine with a factory stock FAST 102LSXr intake and 102TB that picked up 15-20rwhp. I will be waiting. Now if it is a mamofied FAST 102 then I can see 15-20rwhp.

redbird555

iTrader: (14)

I don't even have to look for a 408 a small ls1 will do.....barely anyone puts an ls6 on a 408 because they know it costs power. Here are examples on mild cam to hc setups on stock cubes...Idk where you're living if you think the 2 intakes are even close to being equal on even a cam only setup. I can also add that I picked up 20 who on my old setup going from an ls6 to a 102. The ones he re aren't even 102s.....
http://www.camaroz28.com/forums/ls1-based-engine-tech-19/dyno-comparison-ls6-intake-ported-tb-vs-fast-90-90-ported-668811/

https://m.facebook.com/SpeedIncUSA/posts/493346047343080

https://ls1tech.com/forums/dynamometer-results-comparisons/1091587-professional-products-vs-fast-vs-ls6-intake-numbers.html

http://www.ls1gto.com/forums/showthread.php?t=137522

Longrodlx

iTrader: (1)

My mistake. For some reason I kept thinking this was an LS3 head and intake setup and was comparing the gains from stock LS3 intakes to stock FAST 102 intakes. Yes for a cathedral port 408 stroker setup I would have to agree. But I still think that I would put my cash towards the rest of the build and get the best of the best and if I had to run the LS6 intake for a bit until I got more cash for the FAST intake then that's what I would do. You will absolutely not notice the difference between 20rwhp more or less in the seat of the pants feel. Plus an intake is super easy to swap out. A lot easier than swapping out the totally wrong 317 heads he was planning on using. A good compromise would be running the Texas speed stage 2.5 cnc ported heads and then with the money saved on that compared to going with a set of aftermarket heads that cost twice as much then you would have plenty of cash left over to get the fast 102 and have it ported as well. And with that setup and the right cam there is no reason why you shouldn't be well over 500rwhp and still have lots of torque. Of course as long as you have all the supporting mods and make sure everything is matched up correctly and don't believe the hype that bigger is better like most do and make crap power.

redbird555

iTrader: (14)

The ls3 doesn't gain much when talking about a fast. The only intake mod worth doing on a ls3 is getting gpi or Rick Crawford to port it and add the plastic radius Rods to the inside

Zmg00camaross

iTrader: (11)

Ugh I would want to change that compression something fierce. But if that's not a option then yes fast 102 would help.

redbird555

iTrader: (14)

With those heads the compression drop is likely from the Pistons so I don't think that would be an option

Zmg00camaross

iTrader: (11)

I know that's why the ugh lol, if it was me it would drive me nuts, and I would end up changing the pistons or anything to bump compression.

NAVYBLUE210

What are platic radius rods? Any links?
Thanks

kyleholt11

iTrader: (3)

Read my thread and youll understand why NOT to use a ls6 on a 408...
https://ls1tech.com/forums/dynamometer-results-comparisons/1772986-408-build-please-critique-numbers-433hp-390tq.html

kyleholt11

iTrader: (3)

I managed to squeak 450whp out of her only after going speed density and removing the maf, lid and air filter. My combo chokes out after 5700rpm really bad. Starts pulling a vacuum in the intake manifold.

redbird555

iTrader: (14)

So this one example makes the fast useless? Never mind the other 99/100 people that gain power with a fast.

You made ok numbers for your altitude and rear but you never even tried a fast int hat thread... you're still leaving atleast 20hp on the table.