So, I am building a stock bottom ls3 to put in my c5z. Without this thread turning into a cathedral vs rectangular port argument, and without the cost per performance argument, I have some info to share, and opinions in return.

Since I have neither head, I have decided to go with the cathedral port since I already have a FAST102 intake. After a LOT of research and conversations with Mike at TEA, and Spinmonster, I settled on the Trickflow 235 head.

However, when talking to a lot of other shops and technical experts, the response I almost always get is "235 is too much head for stock displacement". And I just can't understand why? It might have been true for hte ls1 3.9 bore engines, but doesnt make sense on the 376/ 4.060 bore. 235cc is SMALLER volume than the stock l92 head, and the flow is still seemingly less than a ported l92 head.

I pulled data together from Hot Rod magazine's header challenge, I did this because then all the flow bench data is from the SAME bench, to help make an apples to apples comparison. That data is attached below.

As you can see the TFS 235 falls right in the middle of a stock LS3/L92 head and a reputable/proven shop's ported L92 head.

I know there is more to performance than just flow numbers, BUT with the flow data and the fact that the volume is less, I dont see how they can be too big?

 

Also, I have more data compiled that compares more of hte cathedral port heads, as well as the more mild ported LS3/L92 heads. But wanted to start with a simple comparison to spur conversation.

Here is the origin of the data:
http://www.hotrod.com/techarticles/e...t/viewall.html

 

Here is with the GMPP ported LS3/L92 which is more mild... notice the intake lines up very well over top of the TFS235, until you get to 650 lift

 

Can't compare port volumes against the TFS head. It's runner length is longer and will have a larger volume in relationship to the CSA when compared to stock 15* heads.

What is the CSA of the 235?

 

What you're doing is a smart move. I removed my L92 heads off of my 6.0L L76 engine and replaced them with cathedral port AFR 230 V2 heads (230cc runner) and a Tony Mamo ported FAST 102. The engine consistently dynos 30-40rwhp better than the best stock or ported L92/LS3 headed 6.0L G8s with comparable mods on the same dyno.

I would expect the same results with TFS 235s on a larger 6.2L engine. One thing to do though is have your FAST 102 ported by a pro. While porting of them doesn't seem to benefit the rectangular port LS3 FAST 102 intakes very much, it really does help the cathedral port FAST 102s.

 

Patrick,
What are your thoughts on catheral port heads (TEA STG2 LS6 or AFR 230 V2) with VVT? Did you notice much difference in bottom end when you switched to the AFRs?

 

All you can do to these intakes is port match the runners on the fast 102's! There's really NO need to pay ANYONE $250-500 for "Porting". I'd go with the TFS heads hands down.

 

Good to know

 

Your logic seems kind of circular here. While I did not know the runner length was longer (which would not make it too "big" it would just shift volumetric efficiency (torque) lower in the rpm, conversely larger CSA will shift the efficiency higher in rpm) if it is longer, then the the CSA would clearly be smaller than the LS3, in order to still have a smaller overall volume. But maybe I'm missing something still.

Not sure of the CSA of either of the heads, but it is very interesting you brought it up, I guess finding our would be benefical for further studies.

Either way, I still dont see the TFS being too big of a head, unless someone would argue the ls3/l92 head is too big on an ls3/l92.

I just wish I had the money to buy both heads, test them back to back, then return the other.

 

That is pretty much what I am thinking, seeing you post about your results during my research is one of the reasons I convinced myself to go down this route.

 

Do it! I'm going that same route! I was convinced also, after reading Patrick G's thread. I looked at it from a stand point of, if he's making 500rwhp with a 6.0 and afr230v2's through an auto trans, I should be able to do it with a 6.2 and tfs235's! If his 6.0 can handle 230cc heads, a 6.2 can def handle 235cc heads with all else being equal (ported fast, custom cam, lt headers etc...).

The only difference in my combo will be running the fast lsx-rt 102, since my El Camino has the room for it.

 

Ah your lucky those RT manifolds are supposed to be much better than the standard fast.

OP, I think the TFS should do you fine when you look at Pat G's set-up, those guys at TEA wouldn't have sold you the 235's over 225's if they didn't think it suited your combo. Yours should be pretty similar in set-up to Pat's. Get you a custom cam and let her rip!

 

Maybe I wasn't clear. The TFS's head would have a larger volume (in cc's) than say a ported set of LS6 heads with the same CSA. The TFS heads have a shallower valve angle and a longer runner. It's like comparing a 23* SBC head to an 18* based of runner cc's, you need to compare CSA's not just the volume.

 

So, I am remembering to come back here and share the results...

Dyno numbers have been determined and before charts, here are the results:

TPR: (DynaPack)
517/490 as the car sits

Cincy Speed(dynojet)
500/463 with the mufflers detached (still has the 3"- 2.5" restriction, but no mufflers)
494/456 as the car sits with exhaust. (I will get into the details of why I detached hte exhaust shortly)


Let me say that what really impresses me, is the torque. I am making nearly 400 ft*lbs by 3k rpm... and dont drop below that until 6700rpm. The HP is a littler lower than I was 'hoping' but still great. And I have the strongest suspicion this is due to the smaller primaries than ideal.

On to dyno plot fun.... All dyno data off dynojet, which they say "reads lower than most"

Final tune - blue / No mufflers - green

As you can see the stock Ti mufflers are pretty good. I only picked up 6 peak hp, and 7 ft*lbs of tq. BUT in the low/mid range I picked up +20 ft*lbs with the exhaust off.

The reason I took the exhaust off was because it was noticible in the datalogging that I was choking the engine in the upper rpm (i will have that plot later), so was trying to trace it down. I believe the largest contributer of this, is the 1 3/4" primaries that I have, opposed to the 1 7/8" that most LS3 guys run. It seems to be costing me top end HP, but I am getting pretty impressive midrange tq with them.





Since all dynos are different, and will give you different results depending on where you are, and what dyno you are on. I did this to try show an 'apples to apples' comparison of my build to other similar LS3 builds on the same dyno.

Red - me
Blue - c6 LS3 with similar cam spec, vararam intake, SW 1 7/8" headers and SW full 3" exhaust... (stock heads+supporting valvetrain)


Red - me
Green - 2010 Camaro with nearly the same mods as me (G6X3, 2" headers, 3" exhaust, FAST, etc...) - note camaro will have higher drivetrain loss.


I think this 'relatively' definitively shows the advantages the TF235 heads are giving me. It is also worth noting that my exhaust ports are 1.57 (TF225 dia) in size. so slightly custom.

Red - me
Green - completely stock LS3 c6 corvette
Blue - tune only LS3 corvette (same car)





On to playing with the dyno just for fun.. (all these are final tune in red, and no mufflers in blue)

changing from SAE correction, to STD correction, haha


And uncorrected...

 

Thanks for posting this. Makes me want a set of TF over my prc 5.3 heads on my l92. What cam profile did you end up using?

 

Lgm g6x3

 

very cool. what cam are you running.

 

build details...

-LS3 short block
-LG Motorsports G6X3 camshaft
-TrickFlow 235 cylinder heads, milled 0.040" (11.68:1 CR) w/ powdered metal valve guides and custom exhaust valve sizing + some anti-detonation work to chambers (compliments of Brian Tooley)
-TrickFlow Platinum valve springs w/ titanium retainers
-COMP Cams hardened pushrods
-COMP Cams trunion upgrade kit
-LS7 lifters
-Melling 10296 high pressure/high volume oil pump
-Katech C5R timing chain
-ATI super damper (10% underdrive)
-McLeod RST twin disk clutch
-Tick Performance clutch master cylinder
-Tick Performance remote speedbleed line
-LG Motorsports Pro long tube headers (no cats) - stock Ti exhaust
-FAST102 intake (port matched by B. Tooley)
-Siemens DEKA 60lb injectors
-Vararam VR-B2 ram air intake
-Vararam power duct
-LS2 90mm throttle body, with 90mm ring on intake - hand polished ID
-Racetronix fuel pump hotwire harness
-Racetronix cam sensor harness
-Racetronix knock sensor harness
-Racetronix throttle body harness
-EFI Live tuned

 

Juiced,
Thanks for the update. BTW...... not everyone knows the specs of certain manufacters cams based off names. I know I don't.

 

Right, unfortunately LG Motorsports does not publish their cam specs... though the common belief is 235/242 .647/.621 111lsa on lsk lobes.... but the only way to 'know' is to measure it.