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I am doing a H/C swap from stock this Summer and am wanting to get opinions on which heads/cam I should go with. Only reason I am posting this is because I haven't seen this exact situation with cylinder head comparison posted before. I recently bought some bare 243s from a member on here as well as some z06 lightweight valves that I was going to send to A.I. to have the 226cc program worked on. I am in the heads/valves $580 total so far and was planning on reusing my valves from my 317s but found this listing on the z06 valves which I thought would be a nice benefit for my valvetrain to include so I went ahead and bought them.
I am having conflicting thoughts on if I should spend another $60 to send over the 243s plus the shipping back and risk something being wrong with either them or the valves and having to pay more than I thought and also the downtime of waiting for the work to be done by A.I. vs just getting some new PRC as cast 225s in a cam package with something like the torquer v2 or v4. The cost should be similar between either and I would imagine the numbers would also be similar as well.
I am trying to see what people's opinions are of the A.I. worked 243s with the lightweight valves(70-72g intake, 65-67g exhaust) holding against the PRC as cast 225s which I'm pretty sure for $100 more can get at least the hollow intake valve. Is there going to be that big of a difference between the 2? This is for a 2002 M6 T/A with 1 7/8 SE headers w/ORY pipe, 25% ud pulley, lid, catback and stock LS6 intake and clutch(for now). It will be a 100% street car for now. I would like to see at least 420rwhp.
Here is the cost breakdown I am looking at keeping in mind I already have the LS2 timing chain, new standard oil pump, head bolts and timing cover/cam, o2 extensions, underdriven belts, Morel 5315 lifters and 42# injectors:
Send to A.I.
$580 243 heads
$120 round trip shipping
$1795 226cc/cam package which includes head gaskets, pushrods, cam, valvesprings
$195 for titanium retainers
= $2690
cons: potential for cracked head, bad guides, shipping heads, might eat some money on selling heads/valves, etc and potentially spend more $$$
pros: lighter z06 valve a.i. heads, lighter stock casting heads than aftermarket???
PRC as cast 225 w/cam package
$2449 maybe $100 off it I catch spring sale
$75 GM head gaskets
$170 shipping
= $2694
cons: would need to sell off 243s and z06 valves
pros: brand new heads with faster processing time
Id go for the new PRC heads.....will it make more power?? not sure but I bet both will be within a few hp of each other but you will have NEW heads and will be able to sell off your old ones
Plus you will have room to grow with the PRC heads and they will have more of a resale value then the ported stock heads
That's what I'm thinking now. Curious to more opinions. Also was just looking over the 243s I bought and have some questions. Hopefully they aren't bad, but I don't know much if anything about what they should look like. I'm concerned about the what look like gouge marks (looks similar to piston reliefs) from the valves on the intake side. It's on all 8 chambers so maybe it's normal? Hopefully photos aren't too big.
PRC225's are far superior to 243's. Deck surface, 6 bolt design, port shape . plus you can have someone hand port them bigger.
. I can actually knock a few hundred off the price of them if youd like to order a set through me ! im a Dealer for tsp.
Good to hear. That would be amazing. I'm looking to buy closer to Summer so I'll let you know then. Anything you notice on the photos of those 243s to where I wouldn't be able to sell them?
I do plan to step up to a 402 aluminum or stroke my LQ4 sitting disassembled in the garage out to 408 so I'm sure the 225s with additional porting would be nice.
looks strange how its the same in each intake port, maybe someone else will know maybe a casting design
That's what I thought too. Hoping someone can tell me these aren't wrecked.
I guess I overestimated how much the true z06 valves were worth on a normal spinning engine. I'm just learning at this so I'm sure I can sell those and make my money back.
You have a $4 difference in your pricing and you listed selling the 243 heads as a con, that's a pro. Cause then you have approx $400-$500 back in your pocket.
So now the total price for the as cast is about 500 less
Then Mavn also offered a discount so you're getting close to 700 or so cheaper than the 243 setup and you'll have brand new heads with benefits you can't cut into an OEM head. Thick decks, better valve angles etc. I assume they have better valve angles than OE heads, most aftermarket heads do.
They will likely perform similarly, but the hp ceiling should be higher with the TSP
You have a $4 difference in your pricing and you listed selling the 243 heads as a con, that's a pro. Cause then you have approx $400-$500 back in your pocket.
So now the total price for the as cast is about 500 less
Then Mavn also offered a discount so you're getting close to 700 or so cheaper than the 243 setup and you'll have brand new heads with benefits you can't cut into an OEM head. Thick decks, better valve angles etc. I assume they have better valve angles than OE heads, most aftermarket heads do.
They will likely perform similarly, but the hp ceiling should be higher with the TSP
Good points. Dont know why I stated that as a con. It seems like going with the prc heads is the best choice at this point. Now to try and sell off these heads and z06 valves and not lose too much money.
Haha one of your posts about light valvetrain was what made me jump on those z06 valves. But I underestimated the value of having brand new heads with more potential. Do you think I should pay the extra bill for the hollow intake valves they offer on those?
Isn’t it only $100 extra? Might as well if that’s the case, unless they have a higher failure rate
Yeah only an extra bill. I've read it's usually a bad combo of valvetrain parts that cause the failures on the hollow valves. Since I'm not building a track car, I guess I won't be spinning the motor too high though so wonder if it's even worth it now.
Shooting for around 420-440rwhp with the ls6 intake.
Take the extra near grand you'll have from going with the PRC's and throw the above plan in the trash.
And buy a good intake. Why do heads cam to slap a big restriction on top of it all?
A lightweight valve train is always good, but a controlled valve train is most important. Without knowing all of your goals and RPM range it's hard to say if you should opt for the lighter valves.
I'm really hoping those grooves in the combustion chambers where the valves lay weren't cut into on purpose but it's looking like that. The best I could find on the subject for now: https://www.bmw2002faq.com/forums/to...-modification/
If so, I may be SOL on selling these heads.
01-17-2019, 08:38 AM
z06 243s vs PRC as cast 225s 
