camarof41_383

iTrader: (7)

I'm starting to buy parts for my carbed 408 LQ4 build and I'm trying to decide what heads would be best for my application. This engine will go in my 84 camaro, its mainly a race car but sees some weekend street time going to cruise ins and car shows. My goal is to run low 10's N/A with pump gas and keep it streetable. Right now I have an old school pump gas 383SBC running high 10's in the same car so the chassis/suspension is set up well. Heres the basics of the combination so far.

car weighs 3380 with driver
408CID 11.5:1 compression
Vic Jr Intake(probably need a super vic but have limited hood clearance)
MSD ignition

spohn tubular k member w/ coil overs
spohn LCA's, relocation brackets, panhard bar, torque arm
koni 90/10 adjustable struts
50/50 rear shocks w/ air bags
4.30 gears
th-350 trans
27560R15 drag radials
6pt roll bar


Right now I'm leaning towards the TEA cnc ported trick flow 235cc heads. I'm also considing using the L92 heads that I already have and get them ported. The TEA trick flows cost about $2500 and I could have the L92's fully race ported for around $1300...just not sure if the trick flows are worth the extra money. I'm also open to any other suggestions?

key4

iTrader: (10)

Dont really know anything about the trickflows but lots of guys are running good numbers with the L92's. I say if you already got them I would use the
L92's

camarof41_383

iTrader: (7)

I know all flow #'s are relative and all flow benches are different but here are some flow #'s for comparison. These are for the TEA trick flow 235cc heads.
lift IN EX
0.1 67 58.3
0.2 146 124
0.3 235 199
0.4 293 244
0.5 329 265
0.6 344 276

Here are some flow #'s from a set of ported L92 heads from a local shop, the intake runners were 260cc after porting. This head porter does awesome work, he did the port work on my dart heads on my SBC.
Lift IN EX
.2 154 110
.3 222 155
.4 266 187
.5 309 209
.6 345 235
.7 358 247

The only downside I can see with the L92 heads is the lower exhaust flow and the intake runners after porting would be around 260cc. I'm sure the right cam can compensate for that but I'm not sure what the overall power difference would be.

camarof41_383

iTrader: (7)

Anyone else have any suggestions?

sixt9er

iTrader: (2)

I would say if you have L92's, port them and run them. Keep in mind that the L92's use a different rocker arm type and a different intake manifold as well. Sometimes that is a factor for budgeting reasons. I had my L92's CNC ported and these are the results:

Lift: Int: Exh:
.300 226 168
.400 289 212
.500 327 243
.600 353 260
.650 364 266
.700 368 271

Pretty decent flow numbers, with the bare minimum amount of material removed from the intake ports...attention to the exhaust ports was emphasized due to the L92's lack of flow on the exhaust side vs. the intake side.

Flow bench numbers are not the only thing that matters, but they are a good indication of how heads will perform with a given combination.

I would contact a few sponsors and get a cam cut for your needs and application for those heads also, as the cams for L92 headed engines require special attention.

Most aftermarket heads seem to be a bit "stronger" in the valve spring seat areas and rocker arm stud areas as well, allowing you to run really aggressive (solid) cams vs. the L92 heads. Just something to consider when choosing a head for a performance build.

Good luck with the build.

IH8FORD

iTrader: (6)

I have a 10.8-1 408 with ported l-92's. Patrick-G speced me a cam for it. But my cam and converter are heavily biased for the nitrous. I run a GMPP 4150 intake and accu-fab 4150 TB. With a race weight of 3530 i ran a 10.70 at 126 on motor. Keep in mind that is with a super tight converter and a cam speced for a 300 shot. I think for what you are trying to do you should run the l-92's un-ported. At your race weight and no power adder i dont think you'll benefit much from porting the heads.

camarof41_383

iTrader: (7)

The heads I have are actually 317 castings so I'm not sure if I can achieve the compression ratio I'm looking for. So I may have to buy another set of heads anyway. I haven't bought any of the engine internals yet so piston choice is still up in the air too.