Jason 98 TA

iTrader: (4)

Guys I spent several days working on different dyno combinations for the l92 headed engines. We recently dyno tested our 418cid l92 stroker with both the stock & Precision Race Components CNC ported L92 heads. Both cylinder heads were setup with the same chamber sizes & both heads used bone stock valves.

The 418 was built 11:1 with a lxer 242 duration intake & a 251 lsk exhaust. 111+2. I'll get the exact camshaft specs for you guys later on.

Base line power with this camshaft & stock heads was 604fwhp & 555lbft torque. The torque peak was at 4900rpm & the hp peak was at 6200rpm.

Without making any other changes we swapped over to the PRC CNC ported l92 heads & stock valves. The engine proceded to make several pulls into the 630ish range. The pull I printed went 570lb ft of torque @ 5100 & 631fwhp & 6400rpm.

At 3800 where the pulls started the stock & ported cylinder heads made within a couple of horses of each other. Past that point the couple of horse advantage quickly started to rise.

Shortly I'll post a dyno video of the l92 making dyno pulls. I wish I'd had decked the heads for some extra compression, but we just ran out of time.

The stock heads typically sell for about $850 a pair. Add double springs to that $850 & you quickly spend $1100 for a bone stock pair of heads. The fully cnc ported PRC cylinder heads will sell with stock valves for $1499! So basically for $400 you can gain a minimum of 27 additional horse & 15 lb ft of torque! Not bad for $400!!!

All & all I'm pretty pleased with the results. I wasn't sure how much power the motor would pickup when swapping a 350cfm head for one that already goes 308 or so. We hope to do some testing with stainless aftermarket valves in various sizes here shortly.

I'll keep you guys posted & I'll get some info together for all the different camshafts we tested in the next few days.

StingrayCrazy

iTrader: (5)

Very nice numbers! Waiting on the graphs

Frank

pdd

iTrader: (3)

Wow

bad2000z

iTrader: (4)

HOLY ****!! I gotta build a motor....

Big-DEN

So now were seeing the L92 heads and intake finally start putting out the numbers we were hoping for.

BlackHawk T/A

iTrader: (3)

I wouldn't say that just yet - keep in mind those are engine dyno numbers, not chassis dyno.

They aren't that different from the other motors just over the 500rwhp mark on a Dynojet.

Still very nice gains from porting, more than most people expected.

Hard Core Z28

Very nice keep up the good work!

motorbuilt

iTrader: (17)

Using all new parts with PRC valve springs I did my stock port L92 heads for $960 total. All new parts from SDPC plus valve springs from a sponsor...

$540 port job...still seems fair though for a cnc port.

gator's 99TA

iTrader: (2)

would definately like to see a graph. things looking good. 630+ hp at the crank and we are just at the tip of the ice burg. a cam that big and it peaks still realitively low

Big-DEN

Well the older L92 head numbers were lucky to make 550HP at the engine and 500TQ at the engine.

Lucky to crack 500rwhp/480rwtq.

Using 12% drivetrain loss your numbers equate to: 554RWHP and 501RWTQ

JakeFusion

iTrader: (7)

Typically you'll see a 75rwhp loss on a Vette (depends on an F-body's rearend). That puts the numbers at 556rwhp with a Vette.

2c5s

iTrader: (11)

\

It took close to 10 years of aftermarket catch up to make those numbers. Now a 1,400 head and 200 intake make them after a couple of months of the parts being out.......

JakeFusion

iTrader: (7)

550rwhp with 11:1 is very good. The cam would do even better with an 11.5:1 or at the high end, an 11.9:1 CR. That'd be good for another 20rwhp, and that'd put the combo near 575rwhp using the Vette example from earlier.

WKMCD

iTrader: (2)

The only problem is - as we discovered - these heads like a lot of timing. At 12:1 we could only put in 24 degrees. We dropped it to 11.3:1 and now run 30 and picked up both RWHP and RWT.

1bigcam

iTrader: (9)

how do these heads compare to the livernois cnc ones?

ScottyRocket

Haven't most of the other builds that have "struggled" to make that kind of power only 6.2L? These heads love bigger cubes.

This sounds about right for this size engine/combination. If you want any more....more compression, higher rpm w/cam, bigger valves, etc. But for basically stock parts, this is a killer setup.

And yes, there is a big difference between Engine Dyno numbers and Chassis Dyno numbers. Chasiss dyno numbers are lower by usually 15-30% depending on the vehicle drivetrain and oils used.

Bader-X

iTrader: (2)

not impressed by the ported numbers!

if they were from an already ported set of heads then additional work was done then yeah it`s good ....

but 27 hp on an engine dyno? with an engine that already has a big cam .....

304-305 cfm to 350 cfm (though somebody flowed them and reported 32x) is really great but why didn`t it translate to more hp?

but for $400 from your calculation it`s really worth it more power for the price of an aftermarket TB

congrats on the combo numbers and thanks for providing lsx users with another great product that is not expensive.

WizeAss

iTrader: (5)

the big problem here is not the heads IMO..... it is likely the Intake....... Even though the L76 intake flows as good as a stock Fast90....... it is still the restriction here. Those heads need a intake that flows.... so with all the money you fellas saved over having to buy a ported fast 90/AFR head combination....... go pick up a nice sheetmetal.

this is what I plan to do down the road. I just ran out of cash for now. A sheetmetal will add about 40-60rwhp to those numbers peak.

1bigcam

iTrader: (9)

whos intake are you going to buy?

1bad lad

yea the damn l76 intake is limiting the power output of the heads the l92 heads are sweet but the damn intake is killing us we are in the works of a couple things though when we get results i'll let eveyrone know