vettedean

so before everyone says these heads have been discussed before I did a forum search and found nothing...

I'm making the plunge on heads & cam upgrade to my LS1...

expecting to comfortably exceed LS6 stock performance but not go into the "wild" zone for driveability...

cam: Comp Cams XFI XR275HR, LSA 112 degrees, intake .566 lift with 222 degrees duration, exhaust .568 lift with 224 degrees duration

heads: PROMAXX Performance CNC ported LS6/LS2 Stage II heads

these heads flow @

.500 lift 280 CFM intake and 220 CFM exhaust
.550 lift 295 CFM intake and 226 CFM exhaust
.600 lift 304 CFM intake and 229 CFM exhaust

as compared to stock LS1 flow @

.500 lift 219 CFM intake and 170 CFM exhaust
.550 lift 223 CFM intake and 176 CFM exhaust
.600 lift 257 CFM intake and 180 CFM exhaust

as compared to stock LS6 flow @

.500 lift 251 CFM intake and 176 CFM exhaust
.550 lift 256 CFM intake and 180 CFM exhaust
.600 lift 257 CFM intake and 183 CFM exhaust

the balance between cam and heads looks good mathematically so my question is has anybody used a similar combo that could comment on their results?

thanks much...

(BTW these heads outflow Edelbrock heads about 10-15 CFM and are about 10 CFM behind the TEA stage II port & polish to LS6 castings)

LoneStarFRC

While I would agree with you that the numbers look relatively good "mathematically", I sense in your comments that "driveability" will be a definite factor in your final choice of components as well.

I'm sure we can all agree that the terms "comfortably exceed" and "wild zone" are purely subjective terms, and with that in mind, I'm very tempted to suggest increasing the LSA slightly to 114º, especially considering the royal PITA needed (not to mention $$$) to swap a cam if you're not happy with the driveability aspect. Two degrees may not seem like much, but LSA can have a definite impact on drivability and overlap means a lot.. Those heads seem like they will flow nicely.

HTH

tblu92

Without knowing much about Promaxx--I would 1st want to know how much they cost ??
And where they were manufactured----
The flow rates seem normal for some ported LS6 style heads--But the main issue is the quality of the parts they use such as valves--springs--retainers etc---
Also the imported heads seem to lack somewhat in the quality and precision of the port work---basically you get what you pay for----
Your cam choice seems in line for a daily driver type car and not too aggressive on the valve train------Only thought I had was IF your car is an automatic--you most likely would benefit from a higher stall converter---A stock LS1 idles at 600 RPM but with that cam you'll have to idle it more like 800--With a stock converter it might be tough to hold the car still at a stop light idling at 800--hence a stall would be needed PLUS the stall would put the engine up further in the power band that the cam needs to launch--

vettenuts

I would agree with Lonestar with the 114 LSA but I might also bump the cam up in duration to the upper 220 range, something like 224/228.

Do the heads retain the powder metal guides?

vettedean

good points,

there's a pretty good examination of these heads on youtube where these heads are cut into sections to reveal the inner structure of the casting. www.headbytes.com I think...

They use silicon-bronze valve guides rather than powdered metal according to their literature and this youtube destructive disassembly review...

there's a Trick Flow cam that is 114* LSA, comparable lift #s but is 216* intake duration and 220* exhaust duration that I was considering but I think I'll go back now and see if there are any longer duration options out there...

LoneStarFRC

There's a good number of sources for getting a cam ground to your specifications, and not as expensive as some people may think either. If you don't find an "off the shelf" cam, don't worry. Call Geoff Skinner at EPS and give him your parts list and goals and he will recommend one. Call Texas Speed and speak to them about doing the same thing. That's just two reputable sources that quickly came to mind. There's plenty others.

HTH

onspeed

I would go more aggressive on the cam. I'm running a 226/230 .598/.609 111+2 from EPS and wish I had gone bigger. Driveability is mostly all in the tune IMO.

Cheesecake 07

Meh...I'll bite.

You get what you pay for. Comparing flow #'s is as useful as a screen door on a submarine.

Admittedly...I know nothing about the "promaxx" heads but the proof is in the pudding with TEA. They've always went fast and made power.

I'd call BTR(TEA dealer) or TSP if the budget is a restrictor(always is) and I think you'd be pretty surprised how inexpensive a proven *** kicker heads/cam set up can be.

Also...like said above, you can go with plenty more cam and stay out of the wild zone

vettenuts

If they have bronze guides, you should consider an aftermarket rocker to minimize the wipe pattern and side loads on the guides. They will wear fast otherwise. That is the primary reason I run Yella Terra on my AFR heads.

tblu92

Bronze guides are mostly used in racing applicatons where the engine is torn down at least once a year for wear and inspection