'01 WS6 TA

iTrader: (5)

I'm currently running TFS 235's on my 416 and am wondering if there is any benefit in switching to a rectangle port ported LS3... Ive been told its nevessary if wanting to get the motor to the next level. But i dont see thst much of a benefut in flow numbers... Just intake runner size. As it is right now I'm running a 242/251 .624/.624 114 cam and have put down a best of 530rwhp N/A but the motor is peeking at 6100rpm for some odd reason. In the process of working it out and the mention of swapping heads came up.

Thanks in advance, Josh

Gray86hatch

iTrader: (83)

what intake. You can put a really nice set of heads under a bad intake and it is going to look bad

Tim

'01 WS6 TA

iTrader: (5)

I'm running the Fast 102... It hasn't been ported so I'm looking to get that done to see if it helps any. It has 1-3/4 lg pro headers on it and I've ordered a set of 1-7/8 for it. I bought the car with it already built so I'm in the process of swapping out for the necessary parts.

WKMCD

iTrader: (2)

FWIW: My 403 build made 530RW with 3.90's using WCCH Stage 2 L92 heads, a ported L76 intake and a 230-240 cam . More potential with a FAST but it all means you have to know how to put the pieces together. The cathedral port heads are definitely easier to cam. With cathedrals if you want to make more power you just put in a bigger cam and spin it higher...not so simple with the L92/LS3 setups.

'01 WS6 TA

iTrader: (5)

I'd have a can to match the heads to get the most out of the setup... On paper (tfs claims) it says these heads flow in the 340 range and comparing them to my porters ls3 flow numbers they're within 5-10cfm throughout most of the lift numbers. Is that enough of a difference to go through the process and make the swap? Or is the rectangle port more efficient this making more power despite the same flow numbers? I'd run a ported fast on the ls3 head also,

Josh

litle88

iTrader: (20)

Intake Runner size dictates your peak, I was in the same boat as you and I decided to go with a set of LPE Ls3's milled to 65cc's for a 12-1 compression cam is in my sig and on a mustang dyno it put down 542/525.
Don't waste money "porting" these FAST 102 Ls3 intakes have nothing to port! Chris1313 came over and opened her up, all we could do was match the intake runners to the cyl head runners. That's just my .2

WKMCD

iTrader: (2)

All if this is just my opinion but I think peak numbers are going to be similar with either head properly utilized. What I like about the LS3 heads is that you can accomplish that number with a much smaller cam resulting in better drivability for those that give a dam..which I do. Tip in is insane and the car will roast the 345's from an idle. All done by 6400RPM. What's not to love just remember what I've said about the difficulty in finding the balance in durations, lsa, compression, spark lead, etc.

WKMCD

iTrader: (2)

It helps if you have some hours on an engine dyno and the willingness to risk modifying runner lengths, taper, bell mouth, etc. knowing that you may throw the whole thing in the trash when done if it doesn't work.

litle88

iTrader: (20)

I agree 100%
You also gotta know how to build them and know what parts to get. All has to work together.
At AES doing the short block



Finally in my front room.






Built not bought.

lemons12

iTrader: (71)

How about a 40X with the heads mentioned?

I was running an l92 top end on my 370 and the mid range was horrid compared to the top end. However, I don't think the TSP 231/236 cam was helping that any.

01 Ws6... I'm supposed to meet with a guy Thursday for him to buy my 370.. If that works out, I will be in contact for your TFS heads. I wasn't tire kicking, just planning ahead.

lemons12

iTrader: (71)

I just see the cathedral being better suited for a 4.03... Didn't mean to hijack.

'01 WS6 TA

iTrader: (5)

I know the in's and out's of a cathedral head build... Back in 03 I had one of the fastest stock headed cars in the country running 9.40's. I'm new to the rectangle port game... And was just trying to get info on them. No doubt I can build this motor to run its *** off wiyh these heads... just trying to get a few opinions bc I was told by a well known head porter in Dallas that the ls3 was superior from a maximum power standpoint.

lemons12

iTrader: (71)

I could list all the detail if you want me to... But one HUGE thing that made me shy away from the rectangular post was my 370 l92 top end VS my 408 cathedral.

I got the jump both runs but from 30-85/90mph the 408 was pulling back so hard I honestly thought it was going to put a solid 2-3 lengths on my after puling back the car length lead I already had.

Once I got high up in the RPM range and it stayed there (3rd gear) I stopped the 408s pull and we stayed dead even all the way until 125-130MPH.

FWIW... I bought the 408 car built like you did.. It has 1 3/4 headers/fast 90/ and some 243s ported by patriot that flow a whopping 302CFM.

Now it may have been the cubes/torque showing in the 408... But it still changed my mind. It is a different ball game for you 41X guys but on the 40X and smaller motors, I don't think I'm a fan.

All I have heard about the rectangular is CAM CAM CAM selection is KEY!! It will make or break the entire combo.

Always2Slow

iTrader: (8)

Not only will cam selection make or break the combo so can a valve job especially when you get into the bigger cams. In all honesty I am surprised I don't see more people going for a sheet metal intake on some of these builds. Runner size and flow would be easy to achieve.

KCS

iTrader: (20)

It's just bigger. The cathedral heads are still very good heads, but I'm not convinced the LS3 style is any better.

Have you considered LS7 heads?

87silverbullet

iTrader: (11)

I assume you mean small bore LS7's like the PRC small bores since he has a 416?

KCS

iTrader: (20)

Sure.

'01 WS6 TA

iTrader: (5)

Yes ive considered a small bore LS7... Although I haven't really seen any numbers track/dyno been put down with them yet. And some have told me that although they flow well bc of the huge valve, the throttle response will be crap bc of the shrouding against the cylinder wall. Looking at those you can definitely see an increase in flow numbers though.

litle88

iTrader: (20)

Diet coke is running them and he it seems he's been happy except for a few details but otherwise ok.

KCS

iTrader: (20)

Here's a relatively mild 402 that made 536whp. No throttle response complaints at all.

https://ls1tech.com/forums/dynamomet...ore-c5z06.html

You have more displacement and with more compression, I'm sure you'll make some very respectable gains.