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What I got at before was that both seem to flow well according to there own flowbench numbers, but we were not shown if the fed heads were flowed with an exhaust pipe or not which would alter the results. The fed heads do still make good power and have a strong mid-range and use stock valves. The tea will make more at the top end and all the good benefits of a custom head, but at $1800 vs $950 it's easy to see where the value is and that's in ls6 heads, worked by a pro. I made it clear in my other posts that although the fed head appeared to have more flow in the mid range according to their statistic that it may not tell the whole truth, the ls6 head is still a strong contender when considering performance per dollar.
Straub Tech appears to have a good 243 CNC head out there now. Ports designed by Scott Foxwell, so should be good performers. 306/241 cfm at .600" lift.
I had my 243 heads off my Gen4 5.3 CNC Ported by TSP-PRC. Did the Stage-1, and had them mill the Chambers to 63cc. Great work for just under $800 after shipping. I did a cam swap at the time, so can't comment on the power/torque difference they made.
I made 367-Hp at 6,000 Rpm and 348-Tq at 4,800 Rpm at the rear wheels. Estimated 450-Hp/430-Tq at the crank.
Last edited by 07NBSChevy; 07-21-2018 at 04:53 AM.
Dynos vary greatly and so do combos. Any info that isn't before and after in very similar conditions is not worth much. That's why I had the LE heads flow benched before and after on a third party bench. If you guys are posting these numbers to help out Texas Speed (PRC), stop. Those numbers, though just numbers, kind of suck. My Jegs budget, 228/230 cam and bolt on Z28 made 392 on a Mustang MD 250 with stock 241 heads, in the gulf coast heat.
ALOT of guys post about PRC results because it's the cheapest around period. Think pricing starts at 650 dollars to cnc port factory heads. Hard to beat the price but I can't speak on their track performances.
ALOT of guys post about PRC results because it's the cheapest around period. Think pricing starts at 650 dollars to cnc port factory heads. Hard to beat the price but I can't speak on their track performances.
I trapped 122 with the setup in my sig and smacking the limiter on every shift due to transmission failure.
I fully intend to trap 125 mph at close to full weight my next outing
Dynos vary greatly and so do combos. Any info that isn't before and after in very similar conditions is not worth much. That's why I had the LE heads flow benched before and after on a third party bench. If you guys are posting these numbers to help out Texas Speed (PRC), stop. Those numbers, though just numbers, kind of suck. My Jegs budget, 228/230 cam and bolt on Z28 made 392 on a Mustang MD 250 with stock 241 heads, in the gulf coast heat.
lol they kinda do, I noticed that before but didn't say anything. But one of them is also a truck so that's part of the issue.
I know my dyno numbers are low. The dyno was acting screwy. What's shocking is that I saw someone post on facebook with 5.3 stage 2.5 heads, BTR stage 4 cam and Fast 102 and his dyno numbers were only 8 hp higher than my BTR stage 2 cam, Stage 1 243 heads and Dorman 92. I'm happy with the drivability of my combo.
I know my dyno numbers are low. The dyno was acting screwy. What's shocking is that I saw someone post on facebook with 5.3 stage 2.5 heads, BTR stage 4 cam and Fast 102 and his dyno numbers were only 8 hp higher than my BTR stage 2 cam, Stage 1 243 heads and Dorman 92. I'm happy with the drivability of my combo.
Well how it performs is more important that what the dyno said. If you're in the mid 11's or so you're doing good.
You can CNC port factory heads for $750/pr. After market heads will cost above $1700/pr., as cast, or $2500 CNC ported (TSP #'s).
Bang for the buck actually sides with the cheapest option unless it's a max effort engine.
I say port the factory heads for $750, and then do a basic conplete nitrous kit for probably less than $1000. So now you have like triple the power for the same price of an aftermarket head
I say port the factory heads for $750, and then do a basic conplete nitrous kit for probably less than $1000. So now you have like triple the power for the same price of an aftermarket head
Exactly. Unless you have the means to spend $$$ on some AFRs or TFS heads, I would just use GM heads.
Curious if folks can share an opinion or two with me on running worked 243's on an LS3 shortblock in my Gen 1 Cts V. I have hunted but not found any threads covering this but I may have missed it.
I have Thomspon CNC Ported and valve job 243's, cam, coated headers, intake, and other ooem refresh bits all bought and sitting my garage. They were intended for a top end only refresh of my OEM LS6. This is a daily and I really need to limit downtime and be as sure as can that I won't find the stock bottom end as the weak link when i do this. I recently made the decision to put a fresh/known short block in instead. For the time/money hand-off I can get an LS3 setup for ~3k.
The choice is between running the full LS3 setup (heads would remain stock other than a checkup and springs) or running my worked 243 that give me higher compression and are ready to bolt on?
As I compare flow rates below the 243's look like the better choice for me on a daily driver NA ~500 whp car. I don't have a sheet metal manifold so numbers above 0.6 lift are useless to me. I'm running the LS2 tbody and a ported dorman LS2 intake. Smarter folks than I, have told me all about intake air velocity being as or more important on an NA motor than just CFM's for power creation. I am interested in good numbers but far more concerned about driveable power / area under the curve.
I'm leaning towards the 243 based how close the flow numbers are below and the added compression of 64CC (LS6) vs 68CC (LS3) with better quench.
I'll obviously be looking at making a change to my cam LS1/LS2 226/232, .578/.587, 115LSA cam. I had gone conservative on the cam as I had PTV clearance concerns with my LS6 and the 0.4 cometic gasket. With the -2CC pistons on the LS3 I should be able to get quite a bit more rowdy without interference.
Last edited by 84FSP; 08-10-2018 at 01:20 PM.
Reason: update
Appreciate the input and understood that they aren't identical for sure. I was sitting here staring at them and thought an updated calc to show delta's and %'s would help. At the lowest lifts I on an NA motor I would assume I'm increasing torque with the lower ~12% decrease. When I look at the midrange and they are +/- 7% I just wasn't sure I was missing anything. Again - this is assuming CFM's aren't the whole story and that velocity matters.
While I would end up selling a bunch of stuff off, I'm not against running the LS3 setup with minimal changes as they are. I'd have to check the headers as I though the LS3 changed from the LS2 in shape.
Velocity not only matters, it's just as important. That is how cathedral port heads have proved themselves to kick square port *** in many situations. Not all situations of course.
07-18-2018, 02:47 PM
