408 with stage 2.5 5.3 heads?
05-26-2009, 08:21 PM
#21
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fast already came out with the LSXR 102mm intake it just hasnt hit the market yet i bet before summer is over it will be out with doing a 408 with 5.3 heads you can use fast 90's LS2,ls6 or ls1 + i heard the fast 90 flows a little less than 300cfm and so does the L76 also you can have the L76 ported incase you want an extra 10 or so rwhp
05-26-2009, 09:24 PM
#22
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It's not that I dislike them, they can be a good head. I don't buy into all the LS1tech hype though. The 5.3's are not the best LS1 head, it's just the only head that some of the sponsors seem to be able to get half way right. They don't make more torque than the 243's, and in stock form they do have a smaller combustion chamber. But after the port work the 5.3's have 62cc chambers and the 243's have 63cc chambers (per PredZ), so there's no real compression advantage there.
Is it the customer making the choice or is it all the 5.3 hype that's making the choice for him?
answered above
Your right they will bolt up and let air in and air out. But they're really best suited for a 3.90 bore. So with a 4.03 bore the combustion chamber is to small and will need some work to match the 4.03 bore correctly. So technical they are the wrong heads, however they will still work.
If he doesn't have the money to put a set of better suited heads on then by all means put the 5.3's on there. But he did ask for opinions about his package. Add for the money and the big bore why not run the L92 heads they will smoke the 5.3's for cheap?
Everyone is gonna have their opinion but in the end it's the owner who will make the choice.
I personally like the 5.3 heads b/c they have great potential. you get a automatic bump in comp. ratio & they can flow great. So why wouldn't I like them as a option, not to mention they have been proven to make power on many different combos.
My point was not to try & say they are better than other heads but that they aren't the "wrong" choice just b/c someone else wouldn't pick them. They do perform & they do work, so they aren't a wrong head for the build. But at the same time they are also not gonna be a optimal performing head either.
Thats the beauty of this hobby. Everyone doesn't have to use the same parts to be happy with their car. Who cares if someone else doesn't like your parts choice as long as the owner is happy at the end of the day. And if these heads are what they have to work with & don't have the money to change heads, these heads are perfectly fine & will make power.
05-26-2009, 09:57 PM
#23
In my case, moving to L92s would be a waste of money. I have a ported FAST92 combo, so moving to a different manifold would be a complete waste and the I don't think L92s are the answer to everything. ET Heads 265cc 4.0s are the one to go with although they are super expensive, both the original poster and I are not running a massive cam for a 408 either which will also hurt #'s trying to break the 500whp mark. But my goal is to break 10.9 with the combo which I think is completely feasible. The 5.3 heads will bottleneck very quickly with this combination but it will have more of a stockish powerband though instead of being a little more peaky. Making it very streetable which is another one of my goals at the moment also. Sorry, didn't mean to hyjack the thread again
05-26-2009, 10:28 PM
#24
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In my case, moving to L92s would be a waste of money. I have a ported FAST92 combo, so moving to a different manifold would be a complete waste and the I don't think L92s are the answer to everything. ET Heads 265cc 4.0s are the one to go with although they are super expensive, both the original poster and I are not running a massive cam for a 408 either which will also hurt #'s trying to break the 500whp mark. But my goal is to break 10.9 with the combo which I think is completely feasible. The 5.3 heads will bottleneck very quickly with this combination but it will have more of a stockish powerband though instead of being a little more peaky. Making it very streetable which is another one of my goals at the moment also. Sorry, didn't mean to hyjack the thread again
http://www.hardcorels1.com/vbulletin...ead.php?t=1613
05-29-2009, 09:11 PM
#26
No way, keeping it and moving to ET 265cc 4.0 heads. The best ported L92 heads won't touch the numbers that they produce along with a custom cam made for those heads and block specs. I will make alot more power in the long run. Yes they are more expensive but when you want to try for 9's NA in a 408, you need the best stuff on the market. Here is a link to the flow #'s if your wondering.
http://www.etheads.com/00products.htm#
http://www.etheads.com/00products.htm#
05-29-2009, 09:29 PM
#27
The heads are fine for a 402/408, just get them opened up for the bigger bore. Some people on here make claims off info they have only seen on the internet and not in person real world results. 403 I helped tune with PRC 2.5 5.3s and 248/254 615 622 112 made 491/472tq. That was with an unported 92/92 and no EWP to get some of the all might dyno #s that some on here are after. Car screams everywhere and is fun as hell on the street. Use the heads and have fun! Keep us posted on updates and Im interested in what your setup makes.
While they weren't designed for this application, we've had many people make power right in this range with them. Some guys just want to move their existing parts over to a new short-block. There's nothing wrong with that. While some guys want to push you a different direction, it really depends on your goals. I think these guys show you that PRC Stage 2.5 5.3l heads cam make good power on the 408 applications!
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Jason
Co-Owner, Texas Speed & Performance, Ltd.
2005 Twin Turbo C6
404cid Stroker, 67mm Twins
994rwhp/902lb ft @ 22 psi (mustang dyno) www.Texas-Speed.com
Jason
Co-Owner, Texas Speed & Performance, Ltd.
2005 Twin Turbo C6
404cid Stroker, 67mm Twins
994rwhp/902lb ft @ 22 psi (mustang dyno) www.Texas-Speed.com
05-29-2009, 09:31 PM
#28
Good job also bro!!!
Jason
Jason
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Jason
Co-Owner, Texas Speed & Performance, Ltd.
2005 Twin Turbo C6
404cid Stroker, 67mm Twins
994rwhp/902lb ft @ 22 psi (mustang dyno) www.Texas-Speed.com
Jason
Co-Owner, Texas Speed & Performance, Ltd.
2005 Twin Turbo C6
404cid Stroker, 67mm Twins
994rwhp/902lb ft @ 22 psi (mustang dyno) www.Texas-Speed.com
05-30-2009, 11:33 PM
#29
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No way, keeping it and moving to ET 265cc 4.0 heads. The best ported L92 heads won't touch the numbers that they produce along with a custom cam made for those heads and block specs. I will make alot more power in the long run. Yes they are more expensive but when you want to try for 9's NA in a 408, you need the best stuff on the market. Here is a link to the flow #'s if your wondering.
http://www.etheads.com/00products.htm#
http://www.etheads.com/00products.htm#
and what do those new e.t heads flow prc L92's flow 360ish i belive someone might have goten 370 by now i hope
06-01-2009, 02:59 AM
#31
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We have a local guy here who has made 49X and 48XRWTQ on a loaded dyno with a 402 LS2 using PRC 2.5 5.3 heads and a 232 238 XER comp cam, 1-3/4 headers, stock water pump, full exhaust, no cutout etc....
02-26-2013, 03:49 PM
#33
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Your right they will bolt up and let air in and air out. But they're really best suited for a 3.90 bore. So with a 4.03 bore the combustion chamber is to small and will need some work to match the 4.03 bore correctly. So technical they are the wrong heads, however they will still work.
02-27-2013, 06:13 AM
#34
By opening up the chamber you can optimize the flow, but you don't "need to". Just for the record I'm running a set of very worked over 241 heads and very happy with them.
