lt4 intake for afr's?
06-06-2009, 09:47 PM
#1
lt4 intake for afr's? hey guys does anyone out there know if i will need an lt4 intake to go with the AFR lt4 heads or does it not matter. i just bought a set of AFR 227cc competition flow LT4's. Also, i have both lt1 and lt4 intakes so either one is fine. i would like to use the lt1 int. because it has already been ported. but i could also get the lt4 ported too. thanks!
06-06-2009, 10:20 PM
#4
naw get the gm lt4 race gasket pn 12367777. I never even looked at the AFR gasket to be honest with you though. My intake was ported with my cylinder heads, both match up perfectly to that gasket. They only come 1 to a package so I'd order 4 in case you need to pull the intake in the future. You getting those badass 227s hand ported? I had the "race" ported 210s, spent about 800 on hand porting and they flow over 320 cfm at .600 lift. That ported intake's gonna be hurtin me up top 
06-06-2009, 10:35 PM
#5
idk if i will or not. i got the competition flows so prolly not .sounds like you have one bad azz ride there. is the setup working good? im in the process of building a 11.5;1 355 eagle crank etc. still havent decided a custom grind to get yet. have any suggestions?
06-06-2009, 10:50 PM
#6
I moved, but left my car at my folks house about an hour away. There's no exhaust on it yet, and its loud as **** with 12.5 compression. I've put about 40 miles on it, seems to pull pretty damn hard, but its just got a base H/C tune on it. Won't idle below 1200 rpm, blah blah blah. Need a couple days off from work to finish it up, I'll have numbers in a few weeks.
My cam is spec'd for a single plane intake and 250 shot, but stock computer. I got my cam from Bret Bauer who apparently doesn't know anything about anything
if you listen to people on the boards. But fastfatboy is running a solid roller from him doing 10.50s NA at 3600 pounds, proof enough for me.
You're gonna have a tough time getting the full potential out of those 227s on a 355. They'll breath to 7500+ rpm, so unless you're going aftermarket engine management, single plane and solid roller you'll have alot of growing room. What's the car going to be used for, driveability requirements, weight, transmission? Going to be spraying it?
My cam is spec'd for a single plane intake and 250 shot, but stock computer. I got my cam from Bret Bauer who apparently doesn't know anything about anything
if you listen to people on the boards. But fastfatboy is running a solid roller from him doing 10.50s NA at 3600 pounds, proof enough for me.You're gonna have a tough time getting the full potential out of those 227s on a 355. They'll breath to 7500+ rpm, so unless you're going aftermarket engine management, single plane and solid roller you'll have alot of growing room. What's the car going to be used for, driveability requirements, weight, transmission? Going to be spraying it?
06-06-2009, 11:05 PM
#7
the car is going to be driven during the weekends some but mostly want to be a competitor at the track. ( also no emissions around here) i will be spraying the car on a 150/175 shot and stg 3 4l60e w/ a tci anti balooning plate stall for the NX.i know what you mean abot bret. he built the complete motor in my dads z28 its a 383 solid roller,. shift light comes on at 7200 but has spun it well past that.it turns the R's sooo quickly. i dont understand why people arent getting over 7000rpms on stock pcms. i dont know who tuned the car because we bought the car already done but it does well over 7000. but yea bret bauer is waaayyy underrated
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06-06-2009, 11:18 PM
#9
already have the forged crank rods and pistons buttoned up. plan on puttin quit a high lift custom grind in it. i was looking into some LE headwork. then i was looking on craigslist looking for some heads and saw the AFR 227s in there. they only have 500 miles on them. the guy sold them cause he bought an ls1......said they were 2700 new i looked on their website and surely enough. i got them for 1000
06-06-2009, 11:34 PM
#10
like I said unless you're doing XFI or DFI or whatever, its kinda a mixmatched combo. Those heads are going to want rpm on a 355, not gonna be a lot of midrange but it depends on the cam that gets spec'd for it. But then again look at the L92 style heads running rediculous intake ports, though with large valves and a 12 or something degree valve angle. LTX style manifold will hurt it up top as well. I'd bump the compression, to help the torque out maybe 12+:1 comp. You'll have no problem getting the DCR below 9:1 for pump gas. That thing will scream on nitrous though. Since the heads are used, and you should get them resurfaced for flatness anyways, look into getting them milled for somemore compression. Like I said I'm running 12.5 comp static and I'm gonna run it all day on crappy california 91 octane.
06-06-2009, 11:46 PM
#11
i am. i think afrs are 55/or 65 cc chambers so i wanted to mill them down to 54cc's. could my local machinist do this? that puts me at a lil over 11;5;1 comp. or should i mill them more? also, afr's already come w/ a 3 or 5 angle valve job rite?
06-06-2009, 11:56 PM
#12
yea get the heads cc'd. mine are the 65 cc chambers, pistons are .005 out of the hole, with a huge dome and .040 head gasket to get 12.5 and .035 quench. My cylinder head guy I could shave quite a bit off my heads before I'd hit the valve seats, can't remember the exact figure though.
Last edited by Wicked94Z; 06-08-2009 at 02:31 AM.
06-07-2009, 12:14 AM
#14
I can't believe you put those particular heads on a 355. Those are some serious heads. They flow over 320cfm. They will make peak power on a 355 well over 7000rpm with the correct camshaft. Your 355 will be begging for a single plane intake to support the kind of rpm your motor will be singing to.
06-07-2009, 12:21 AM
#15
I can't believe you put those particular heads on a 355. Those are some serious heads. They flow over 320cfm. They will make peak power on a 355 well over 7000rpm with the correct camshaft. Your 355 will be begging for a single plane intake to support the kind of rpm your motor will be singing to.
it has a lightweight bottom end so it shall turn up quickly, it will all play around which cam i get which i need yalls help deciding which custom grind to get 
06-07-2009, 11:32 AM
#18
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Like Wicked94Z stated, get the GM LT4 race intake gasket.
Using AFR 227's on a 355 needs different components than what you're planning. If you want to run those heads with a FULLY ported LT4 intake, you should consider going with more cubic inches; like 408+ with the new Dart block. They're (AFR 227's) already a bit much on a 383-388 stroker without running complementing hardware.
Another option is to run forced induction on a 383-388 with the 227's.
As you have it, it's a mix matched combo to say the least...
Using AFR 227's on a 355 needs different components than what you're planning. If you want to run those heads with a FULLY ported LT4 intake, you should consider going with more cubic inches; like 408+ with the new Dart block. They're (AFR 227's) already a bit much on a 383-388 stroker without running complementing hardware.
Another option is to run forced induction on a 383-388 with the 227's.
As you have it, it's a mix matched combo to say the least...
Last edited by Built LT1; 06-07-2009 at 07:41 PM.
06-07-2009, 06:55 PM
#19
yes i understand. i figured that they may not be getting their full potential but that cant hurt the power it will put out. i will be putting a high lift/duration custom gring so that shall help out. also when i decide to go bigger one day, i already have the heads to do it with
06-07-2009, 07:57 PM
#20
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I predict this car making power, but not ET-ing for squat. No offense. Its just that your going to have no low end power. Remember Large cams are not always better. Get a custom grind to where it will bring the power band down and you will make power through out the RPM band. You dont want your engine to run like a two stroke. Its not fun...TRUST me. Also with these heads, and the big cam you say your going to be putting in it, you will reach the limits of the PCM thats for sure. Just make sure you know what your doing before you do it. (not saying you dont.)