heads for my ls2 408- ported 853's or prc 2.5?
09-16-2013, 09:40 AM
#1
Staging Lane
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heads for my ls2 408- ported 853's or prc 2.5? guys,
getting ready to finally throw my 6.6 in my vette. i have a set of cnc ported 853's on the car now, but in other dealings i have a guy that is wanting to trade me a set of prc 2.5's. im not knowledgeable enough to know if this is a good move or not. i'm fairly sure neither set is perfect for my set up but i cant come up with 3k for big dollar heads right now. cam was spec-ed by martin @ Tick and is a 243/252 .624/595 113 +5 and the intake is a fast 90 tony mamo ported unit. any input?
thanks guys!!
andy
getting ready to finally throw my 6.6 in my vette. i have a set of cnc ported 853's on the car now, but in other dealings i have a guy that is wanting to trade me a set of prc 2.5's. im not knowledgeable enough to know if this is a good move or not. i'm fairly sure neither set is perfect for my set up but i cant come up with 3k for big dollar heads right now. cam was spec-ed by martin @ Tick and is a 243/252 .624/595 113 +5 and the intake is a fast 90 tony mamo ported unit. any input?
thanks guys!!
andy
09-16-2013, 11:46 AM
#6
Those two are pretty much a wash, and you don't need the small chamber 5.3s to build compression in a 4" stroke engine.
Honestly I would not go with either of those for a 408. If you can't afford aftermarket heads get a nice set of LS3s with a valvejob and come be out only a few hundred bux after you sell the current ones.
Honestly I would not go with either of those for a 408. If you can't afford aftermarket heads get a nice set of LS3s with a valvejob and come be out only a few hundred bux after you sell the current ones.
09-16-2013, 11:52 AM
#7
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Those two are pretty much a wash, and you don't need the small chamber 5.3s to build compression in a 4" stroke engine.
Honestly I would not go with either of those for a 408. If you can't afford aftermarket heads get a nice set of LS3s with a valvejob and come be out only a few hundred bux after you sell the current ones.
Honestly I would not go with either of those for a 408. If you can't afford aftermarket heads get a nice set of LS3s with a valvejob and come be out only a few hundred bux after you sell the current ones.
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09-16-2013, 01:47 PM
#9
Trickflow 235's
AFR 230s
MAST small bore LS3's...
Someone had a good idea though. Sell your ported FAST 90 and the heads, get some LS3's with at least a good VJ, AI ported would be a benefit, and run an LS3 intake.
Unfortunately, you'd be due for a cam swap at that point. Keep your nose in the classifieds. You'd be surprised what you can find.
If you're dead set on keeping the FAST 90, Advanced Induction has a fully CNC'd Trickflow 230 head that would be nice.
2295 with springs/Ti retainers.
http://www.advancedinduction.com/LSX...0ccTFSHead.php
AFR 230s
MAST small bore LS3's...
Someone had a good idea though. Sell your ported FAST 90 and the heads, get some LS3's with at least a good VJ, AI ported would be a benefit, and run an LS3 intake.
Unfortunately, you'd be due for a cam swap at that point. Keep your nose in the classifieds. You'd be surprised what you can find.
If you're dead set on keeping the FAST 90, Advanced Induction has a fully CNC'd Trickflow 230 head that would be nice.
2295 with springs/Ti retainers.
http://www.advancedinduction.com/LSX...0ccTFSHead.php
09-17-2013, 11:37 AM
#13
Staging Lane
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martin did me right again...even with a follow up call today nagging him he's always on point and awesome to deal with. the as cast fit my budget well and i can have them ported later if i choose to. going to be much better then what i have with room to grow. thanks guys!
09-17-2013, 12:28 PM
#15
Those two are pretty much a wash, and you don't need the small chamber 5.3s to build compression in a 4" stroke engine.
Honestly I would not go with either of those for a 408. If you can't afford aftermarket heads get a nice set of LS3s with a valvejob and come be out only a few hundred bux after you sell the current ones.
Honestly I would not go with either of those for a 408. If you can't afford aftermarket heads get a nice set of LS3s with a valvejob and come be out only a few hundred bux after you sell the current ones.
09-17-2013, 01:38 PM
#16
The main issue this website has and most LS owners have is they think bigger is better when it comes to cylinder heads.
A larger cam and larger heads will take away more bottom end, mid range and under the curve power than a smaller head and larger cam.
Port volume is the determining factor along with runner length in where the power curve starts and stops and the cam determines much of how it is shaped. If you have a huge intake runner you'll have to crutch the intake valve closing event of the camshaft to gain all of that torque back, and even then you're not going to get it all back compared to a smaller runner.
The lower the rpm of the motor the more important air speed is. The main problem I see in street N/A and turbo motors is too much cylinder head, not enough cylinder head, too much cam or too little cam.
I jokingly refer to it as "Goldilocks" syndrome.
The reality of this is, most 408-427 cubic inch motors, especially those with long runner OEM style intakes like a Fast intake, LS6, LS7, LS3 etc. etc. etc. don't need more than 220-240cc of port volume in regards to the intake runner.
Anymore is just a waste! The OEM style long runner intake will limit peak horsepower RPM to 6500rpm or less, so why put a larger volume cylinder head on it that shines above that RPM and will only take away under the curve power?
It's an age long dilemma that I've seen on this site for a while now. The most valuable words I can give to anyone reading this trying to figure out the best head for their motor is, "when in doubt, go a size smaller."
A larger cam and larger heads will take away more bottom end, mid range and under the curve power than a smaller head and larger cam.
Port volume is the determining factor along with runner length in where the power curve starts and stops and the cam determines much of how it is shaped. If you have a huge intake runner you'll have to crutch the intake valve closing event of the camshaft to gain all of that torque back, and even then you're not going to get it all back compared to a smaller runner.
The lower the rpm of the motor the more important air speed is. The main problem I see in street N/A and turbo motors is too much cylinder head, not enough cylinder head, too much cam or too little cam.
I jokingly refer to it as "Goldilocks" syndrome.
The reality of this is, most 408-427 cubic inch motors, especially those with long runner OEM style intakes like a Fast intake, LS6, LS7, LS3 etc. etc. etc. don't need more than 220-240cc of port volume in regards to the intake runner.
Anymore is just a waste! The OEM style long runner intake will limit peak horsepower RPM to 6500rpm or less, so why put a larger volume cylinder head on it that shines above that RPM and will only take away under the curve power?
It's an age long dilemma that I've seen on this site for a while now. The most valuable words I can give to anyone reading this trying to figure out the best head for their motor is, "when in doubt, go a size smaller."
02-15-2014, 08:17 AM
#17
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bumping this back up...car is at mike norris's shop for install of 408 with Martins spec'ed pistons, cam, heads, head gaskets, springs, lifters etc...i'll post up results in a few weeks. i dropped car off in indy last friday. hoping set up will hit 500/500. should be plenty for a street dd car. 
thanks again martin!
thanks again martin!
