Have a dilemma? LS7 heads or TFS 235 on a 427
12-01-2008, 09:51 PM
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Have a dilemma? LS7 heads or TFS 235 on a 427 I had already decided to go with a N/A LS3 based 416 w/ TFS 235s. The results of a boardmember that goes by "Pray" pretty much sealed the deal. When I talked to my engine builder he had a slightly used LS7 block and LS7 heads for a decent price. The problem was that I had ordered a set of 235s from a sponsor a couple days before. I tried to cancel the TFS heads I had ordered but they said they would charge me fees since the order was already processed. I was not thrilled but i guess it's just business.
So now I have have 2 sets of heads. I don't think I can justify spending the extra money to have the LS7 heads ported so they would be stock.
I have read a lot of the posts regarding the LS7 heads vs. cathederal ports but it just doesn't seem that there are that many LS7 headed strokers and their results. Most of the threads seem to be against the LS7 heads but I can't help but think of all the 570-580 rwhp Z06s. Someone said it was partly due to the lighter valvetrain and wet oil sump system. Seems like some of the catheteral port head strokers are all over the place. I saw someone saying that the 235s are a better choice than nonported LS7s but not ported LS7 heads. That makes sense to me based on what I've seen but not based on scientific data.
Should a 427 having a 4.125 bore and TFS 235 heads be able to reach 575 rwhp (SAE corrected, 6 spd, 12 bolt w/4.10 gears) pretty consistently with the right cam? It has to be on pump gas. It seems like Vengence has had some pretty good results w/ 440 ci motors, some reaching 600 rwhp.
I'm leaning towards the TFS heads beacause of Pray's results but my builder thinks the LS7 heads would be better.
So now I have have 2 sets of heads. I don't think I can justify spending the extra money to have the LS7 heads ported so they would be stock.
I have read a lot of the posts regarding the LS7 heads vs. cathederal ports but it just doesn't seem that there are that many LS7 headed strokers and their results. Most of the threads seem to be against the LS7 heads but I can't help but think of all the 570-580 rwhp Z06s. Someone said it was partly due to the lighter valvetrain and wet oil sump system. Seems like some of the catheteral port head strokers are all over the place. I saw someone saying that the 235s are a better choice than nonported LS7s but not ported LS7 heads. That makes sense to me based on what I've seen but not based on scientific data.
Should a 427 having a 4.125 bore and TFS 235 heads be able to reach 575 rwhp (SAE corrected, 6 spd, 12 bolt w/4.10 gears) pretty consistently with the right cam? It has to be on pump gas. It seems like Vengence has had some pretty good results w/ 440 ci motors, some reaching 600 rwhp.
I'm leaning towards the TFS heads beacause of Pray's results but my builder thinks the LS7 heads would be better.
12-01-2008, 11:24 PM
#2
Look for consistent results if you want to copy a setup and you'll have better luck.
What a dyno reads in one shop is not what it reads in another shop and so if you base your combo off one persons results you might be disappointed unless you use that persons dyno. Thats just a genral rule of thumb and is not intended or pointed at anyone at all.
Z06's have a better exhaust as well so unless you've got a Vette compare apples to apples for similar results.
You dont see a lot of results because it requires at least a 4.125 bore and the L92 427 is not a 4.125 (the poor mans version of the 427)
bore so the TFS 235 gets the call.
The aftermarket head is beefier as well and better suited for certain him rpm applications plus the thicker deck and 6 bolt options make it better in power add applications.
What a dyno reads in one shop is not what it reads in another shop and so if you base your combo off one persons results you might be disappointed unless you use that persons dyno. Thats just a genral rule of thumb and is not intended or pointed at anyone at all.
Z06's have a better exhaust as well so unless you've got a Vette compare apples to apples for similar results.
You dont see a lot of results because it requires at least a 4.125 bore and the L92 427 is not a 4.125 (the poor mans version of the 427)
bore so the TFS 235 gets the call.
The aftermarket head is beefier as well and better suited for certain him rpm applications plus the thicker deck and 6 bolt options make it better in power add applications.
12-02-2008, 06:08 AM
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Thanks for the input. So if you were building this engine for a street / strip application would you use the TFS heads? At this point I don't think I will use nitros and I plan to have the compression somewhere around 11.5 to 11.8.
12-02-2008, 09:19 AM
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Im running the LS7/LS7 setup, reason being was better driveability with a smaller cam, yet similar power output. So better driveability, emissions and economy over a cathedral and similar power output, same goals as GM 
12-02-2008, 02:50 PM
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https://ls1tech.com/forums/generatio...-ls7-head.html
this answers the debate about as well as you could, from my point of view.
this answers the debate about as well as you could, from my point of view.
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12-02-2008, 04:59 PM
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also, the ls7 zo6 cars have a much lighter reciprocating mass (ti rods, cast pistons) and a dry sump, as you mentioned. this is indeed worth rwhp. i dont think 20 is that far off, but thats a w.a.g. on my part.
once you add a heavier bottom end and wet sump, things change a bit. just food for thought.
i've owned both top ends, fwiw.
once you add a heavier bottom end and wet sump, things change a bit. just food for thought.
i've owned both top ends, fwiw.
12-02-2008, 08:24 PM
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Thanks for all the help. I had read that thread before but had thought it was a little slanted towards the TFS head, even though they had tried a second cam. Now that I look at it again, it seems that it may be more informative than I thought. Even if the second cam wasn't the best choice, the heads acted the same way as the first cam.
Last edited by Bill00Formula; 12-02-2008 at 08:35 PM.
12-02-2008, 08:29 PM
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i think the ls7's would be the ticket for a solid roller sheet metal application. but 6500 and below, the TFS are clearly the winner, in my humble opinion. certainly more fun (power) at most street driven rpms.
12-04-2008, 09:59 AM
#15
Robin is probably talking about where he is using silly big duals/triple springs, near 1" lift, where they need tall install heights and you cant cut stock casting spring pocket deep/wide enough to support 400 lb+ on the seat
Youd run out of oiling stability with the wet sump before youd run out of valvetrain parts to turn rpm, 8K isnt much with a solid
Youd run out of oiling stability with the wet sump before youd run out of valvetrain parts to turn rpm, 8K isnt much with a solid
12-04-2008, 11:06 AM
#17
For 99% of guys a 1.4x diameter pocket with a good spring is enough to control your average .700-.800 lift solid roller. Not sure how thin they really are as I dont do alot of solid stuff. .700 lift hyd roller taking us to 8K so I stop there any damn way
