ryan23

iTrader: (5)

482/438 on a Dynojet, SAE corrected...

Mods:
Erik Koenig built 427
RED sleeved LS1 Block, 4.125 bore
Callies Racemaster 4" crank
Callies Compstar rods
Diamond pistons, 11.5:1
Greg Good ported LS7 heads
Patriot Extreme valvesprings
Morel Lifters, stock LS7 rockers
240/250, .640/.610(?), 112 LSA
LS7 Intake w/90mm Holley TB
1 7/8" headers, 3" E-Cutout
52 Lb Ford Injectors (OEM Shelby GT500)
Meziere EWP
Alternator only (BMR Drag kit)
Stock coils
New MSD wires, New TR55's
HPtuners, SD tune, no MAF
in a 93' Mazda RX7, T56, and an 03' Cobra 8.8 IRS.

The motor was tuned by me. A/F 12.2:1 under WOT until 7K. 28 degrees total timing, no KR. I tried swapping plugs, opening the cutout (+2 HP) and that's all she'll give. I'll GLADLY share the tune if you think it's there. From what Erik tells me, I'm down ~90 RWHP. I pulled the rocker covers off and checked all the springs & rockers. They all look good. Compression is 185-200 across all 8 cylinders. Don't say fuel pressure, she stays rich. I pulled the piping off the throttlebody, butterfly open to atmosphere (no restriction there). MAP reads ~98 KPA @ WOT.

Any helpful hints on where to start? This is such a letdown after waiting for over a YEAR for this motor. Hell, I'm at a tune-only LS7 level right now. What gives?

Thanks!

Ryan

Demonicbird00

iTrader: (17)

you need more timing around 30-32 and bring the A/F up to 12.8:1 see where that takes you.

-brandon

1999vetteroo

iTrader: (15)

Pushrods maybe? Did you measure the lenght? They might be too long and preventing the valves from closing all the way. I'm sure some will say that's bs. I know its a long shot but, stranger things have happened. Hopefully someone with alot of experience building 427's will chime in.

WMSuperSport

iTrader: (23)

Maybe try using a different dyno. I know its a longshot but maybe somethings up with the one your using?

If Erik did the motor, I'm sure all the pushrod/valvetrain geometry is correct.

allngn_c5

iTrader: (3)

Your motor does look to be about 70 or so short at the wheels on HP/TQ. Sorry to hear about the results. I looked at your hp/tq curves and they look great, just should be higher. I really hope you figure out whats up. Those numbers can't be right, I made 490/445 to the wheels with my N/A 346. Something is definately up. Have you driven it yet?? If so how does she feel ?? Does she blow the tires off in second ?? If she does then those numbers are inaccurate. Try another dyno. Please. Your combo looks well thought out, so I can't understand the low numbers.

ryan23

iTrader: (5)

The car feels unreal on the street. She'll blow the tires off in second and get squirrly in third. Remember though, I'm dealing with a chassis under 2700 LBS.

Here's some bad news though, I'm seeing some blue smoke under WOT on the street. Not like "Spy Hunter" smokescreen blue smoke, but blue puffs yu can see in the rear viw. Time for a leakdown check?

Erik was pretty adamant about no real break-in time. Putt around for a half hour or so then she's supposedly ready for prime time. It's never been my practice but I figured this wasn't Erik's first rodeo either.

Now I'm not using an PCV system. I've got an LS6 valley cover which is Y'd into a hose coming from the driver's side valve cover breather (via the GM nipple you can buy). That's fed to a vented Canton catch can. I get a little mositure out of the catch can but I've never seen any oil. I had to ditch the breather baffles in the other valve cover due to offset rocker clearance issues. Those two vents are capped off as I figured I would suck oil if I tried to vent them.

FWIW, map pressure at idle is 62-63 KPA, according to HPTuner's scanner. Sound 'bout right?

Ryan

brad8266

iTrader: (23)

MAP @ idle is right. Thats too bad about the low numbers. I would have personally went with a different set of heads like AFR or TFS and also ran a FAST manifold. You could be losing power from the heads and intake, hard for me to say really though. Your TQ drops off right after 6K which is why the power does not increase after 6k, this is not supposed to happen when you have a cam that size, it shold keep making TQ a bit longer and increase power up high in the RPM's. I feel as though your motor is being choked by something, which I would guess is heads and intake. What did the heads flow? Its hard to believe that your 427 only makes 438 TQ and my little 347 makes 415 TQ. Something is holding it back.

If you have good consistent compression numbers than there is not really any need to do a leakdown test.

Hope you get it figures out man, that motor is a beast in that little car.

LS1curious

Sounds like the cam timing is missing the boat.

brad8266

iTrader: (23)

I doubt it, it should make lots of power no matter where the cam timing is. And if it was off that much the valves would be hitting the pistons likely.

Louis

iTrader: (7)

Bolt on LS7s make more than that. Post pics of the setup, and more details.

The Tq. is WAY off, I mean the HP is too, but the Tq at 3k should be 420+, not mid 300s.

Timing is not necessarily needed with that stroke, 28 is more than adequate.

Patrick G

iTrader: (14)

Your curves suggest proper cam timing. Either the dyno had a screwed up weather correction or you're down 1 cylinder. With your tuning software, start turning off cylinders to see if you have a dead hole. My guess is you're not getting spark to one cylinder. 482/7 = 68.9 rwhp/cylinder (if you're down 1). A full 8 cylinders would give you 551 rwhp which is about where you should be.

gnx7

iTrader: (28)

A friend had a similar 427 built and ran a 236/236 115LSA cam. Driveability was great but it only made 510rwhp/500rwtq. With a 252/259 110LSA cam it made well over 550rwhp.. peaking at around 6600rpm. It sounded mean but if you truly want to make big power n/a.... it is in the head/cam combo. Yours is about 20-30rwhp low. That cam in all honesty is pretty mellow.

I like that you have it in an FD

ryan23

iTrader: (5)

So I went back to the shop.....

I ohmed all the coil packs out, 33~35 Ohms. While running, I pulled each wire off the pack and got a fat spark on all of them. I didn't see a need to yank them off the plugs since they're new wires/plugs. I also unclipped each injector, one at a time and got a barely audible change of tone.

Next I did a cylinder balance test via HPtuners. Here are the results:

Ref RPM: 984

Cyl 1: 82%
Cyl 2: 96%
Cyl 3: 90%
Cyl 4: 85%
Cyl 5: 90%
Cyl 6: 79%
Cyl 7: 94%
Cyl 8: 85%

Any ideas?

Ryan

ryan23

iTrader: (5)

According to Erik, he's used this cam before in a couple different engines. Mine, so far, has been the lowest performer (by a wide margin).

Ryan
(The other Silverstone FD )

ryan23

iTrader: (5)

Belay that cyl balance test, I ran it again @ 1100 RPM and I got all results in the 80s. I think it was my cam interfering...

Ryan

Patrick G

iTrader: (14)

Where did you dyno and what were the weather corrections?

Full-Force

iTrader: (11)

I know this sounds silly and redundant but pull the wires and ohm all of them. I have seen many LS1 cars that I have worked on that had 1 or even 2 bad wires and still drove fine and made decent power. Car I just got done with as a matter of fact had 2 bad wires and the wires looked intact. When I ohmed them they were over 300 ohms.

I see you have MSD wires which are the best IMO.

BTW, I would lean it out some. I dont think thats your 90hp that your missing, but that along with maybe finding 1 cylinder not getting spark will be your answer.

Good luck.

WMSuperSport

iTrader: (23)

Use a temp gun on the header primaries to make sure all cylinders are firing.

slow trap

iTrader: (22)

something is obviously wrong. as already mentioned you are 70 or more rw down and tq is way down also.i have only speculations to add just like most but hopefully it is something minor like a bad wire or something.hope you figure it out.

Louis

iTrader: (7)

+1 on the temp gun on each cylinder.

That car has 4.10s, right? It should be all over the place until 4th.

Whats the base circle on the cam compared to stock, and where are the heads/valves setup? Lifter preload might be an issue here as well.