gouldy

Hello All

Has any one compared these two heads?
Apart from the price difference do they have any real advantage over each other?

The PRC look like great value for money and a lot of effort has gone into the 6 bolt design compared to other heads on the market. I am looking at both heads for a boosted 427; after deciding to forget about ls3 and cathedral port heads as they may be a large step back from the LS7 heads.

All opinions appreciated

Cheers
Jason

430 hp 70

iTrader: (3)

subscribed.

i talked to tsp and they plan to have another sale around thanksgiving, christmas and tax time. maybe 200 off their heads again? but that puts the prcs at 2499 with stainless hollow stem valves and the mast heads at 3500 built the same way. how much more power are we going to get for 1k?

SSPerformance

iTrader: (76)

Mast ls7 head hands down

COPO9560

Which MAST head are you looking at? They make a 274 and 305 version.

430 hp 70

iTrader: (3)

why? what makes them worth it? and im being serious cause i think myself and the op really dont know.

gto_ua

Because of port and cc work...

+most of record setting cars use PIS/MAST heads.

gouldy

Looking at these ones however the PRC look just as strong on the 6 bolt set up and the flow figures are about the same and the price is a lot cheaper.

http://www.mastmotorsports.com/2010/...p?cat=Cylinder Heads - Assembled&id=365

http://www.texas-speed.com/p-1236-pr...cnc-heads.aspx

melsie68

iTrader: (8)

While I would say the Mast product is a better one for a number of reasons, I believe you would only really see the benefit in an N/A application. The port designs, chamber design, valve placement and spark plug location in the Mast heads are all a product of years of development by Cary Chouinard. If you look at the repertoire of heads Cary has worked on, the fact that he was one of the first to produce aftermarket heads for the LS platform and such puts a lot in his favor. There is far more to a cylinder head that flow numbers and you can take that to the bank. There are heads out there which can flow more air but make less horsepower. But without getting into all that, a boosted engine just needs a solid casting that will take the stresses involved. If you were building an all-out class motor, then yes you would want the best port available and in that case an LS7 port would not be my first choice. In summary, I think the PRC will get the job done. I would have my local machine shop check the guide fit and valve job though.

...looks aren't everything either...I would be willing to bet the Mast casting is more robust in a number of areas and you can bet the material used is what they say it is AND is a USA casting.

gouldy

Do you think the Ls7 ports will be ok or should I look at another design?

Sales2@Texas-speed

iTrader: (5)

I thought I'd jump in here & throw in a few things in this thread.

Both cylinder heads are nicely made aftermarket castings.

The PRC 285cc heads flow very compareable to the 305cc Mast/PI/ETP..etc.

In a recent magazine test of LS7 cylinder heads, PRC ported 4 of the cylinder heads in the testing. That means four out of the eight or so cylinder heads tested were ported by PRC.

We priced the PRC LS7 cylinder heads very similar to out other aftermarket casting heads because we always work to provide a great product for a great price.

Here's a link to a customers pics of the PRC aftermarket casting LS7 heads.

https://ls1tech.com/forums/generatio...ls7-heads.html

430 hp 70

iTrader: (3)

link?

i really dont doubt that the mast will make more power, but my question is HOW much better will they be for a street car? do i need the 700hp that my combo will make? no. do i really need the extra "x" hp that the mast will make? no. but am i missing the point? is there more to it than high rpm power, or will i see a difference below 4500?

melsie68

iTrader: (8)

The LS7 is more than adequate for what you are doing I would think and either head would probably be good for a boosted application such as you are suggesting. You will more than likely have enough horsepower to keep you scared of it for a while. If you are trying to set some records or be competitive in a specific class there are some more high end options out there that are based on the wedge C5R port and canted valve designs such as the LS-R and Mozez. But you are talking a significant increase in cost for the build.

melsie68

iTrader: (8)

...Is this your thread?

What is your application? Is it the same as the OP's? Engine size, fuel used, weight of the car, suspension type, transmission type, intended purpose, etc...? Whether they make more horsepower below 4500 is a very specific question. The only criteria you have mentioned is "street car" and if you aren't worried about every last bit and then getting to the ground, you won't miss it. But sometimes, you get what you pay for although I doubt someone building a street car will see the difference.

There is another thread on here where a guy is using some rather pricey components for a street car and cranking out very impressive HP numbers. But the guy has no interest in running it at the track or putting the power to the ground efficiently. While I ask the question why bother with such an engine, that person merely just wanted what he wanted. If you want the piece of mind that you bought all the best stuff to make the most excellent engine possible, do like that guy and buy the expensive high end stuff.

I have used Cary's stuff several times and I will continue to do so because the guy really cares about what he produces. Excellent quality, materials, attention to detail, customer service and they flat out go fast on the track. I have seen TSP ported factory castings and out of the box they needed a valve job to make them right. It was about four years ago and could have been the one pair, but they were returned. I don't know if things have improved over there or their aftermarket castings are the same. But I am not the kind that likes to take a chance and personally that isn't the kind of quality control I would pay for, even if it was $1000 cheaper than the competition. Just my .02

For the record I have bought plenty of gear from TSP as well. Good guys down there and good service. I hope no one misunderstands that fact but we also must understand there is always something better out there just like there is always someone that is faster.

430 hp 70

iTrader: (3)

nope. but i was about to ask the same question and if i would have started a thead with the same title you probably would have been the first to refer me back to this thread.

thanks for the reply though. my car is a 3600ish lb 70 chevelle with a t56 mag, 373s, 28.5" tire, custom built 4 link with watts that will see 90% street with the other 10% between the road course and the auto cross. i didnt include all of that since this wasnt my thread and i was trying to be nice, but it sounds like he now has his force induction question answered and i was called out anyways.

i believe this is what the op was looking for, and i know i was as well. id like to hear others responses to see if there is any truth to this still. ive been planning this motor for years and have followed the progress of a lot of the aftermarket companies. i think tsp has come a long way (not that they were bad before) and would love to hear some more recent opinions.

Unreal

If you need any more pictures or questions on the PRC ls7 heads I have them. Should be up and running later this week. My build is forced induction so I wanted the thicker deck and 6 bolt setup for later.

COPO9560

This is going to be a very cool car - keep us updated as it gets further along.

gouldy

Cheers Guys

Keep the feedback flowing; this is just the sort of stuff I need to make a good choice.
Unfortunately every one has different ideas and some people say oh no don't use the LS7 or LS3 because you can use a large cathedral port like a TFS 245 for example and get almost as good results? This is why it becomes very hard to choose a good option.

I am starting with a clean sheet with the heads as I have to buy a bigger blower and manifold to suit the LSX 427 6 bolt block anyway as the cathedral port MP122 Magnacharger I have on my other engine is way to small.

Mast also does a LS3 large bore head that flows about the same specs as the
LS7 mast heads. I wonder if this may be a good option as I will have more Blower and manifold choices with the LS3 heads.

Petraszewsky

iTrader: (28)

I'm am also interested in this debate.. What head will help give him a nice power curve ? I know it depends on what he wants to do with the engine purpose wise. I am debating my top end setup for my build also.

Blunts Auto

I like to see some pics on the PRC ls7.

Unreal

Did you check the thread Matt posted where I put all the pictures? What other pictures do you want to see?