95 Z28 M6 - CC306 w/ported factory heads

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Note: I bought the car as it sits and have only tweaked the tune, so I don't know the exact flow specs on the heads. Stock bottom end, 119k. AFR is 12.9-13.2 at WOT. Thoughts? This seems awfully low compared to what I've seen from this setup. I have Edelbrock shorties, a high flow cat and an unknown catback (Magnaflow I think?). Peak torque came on at ~3k and stayed there, power climbed until redline. One theory is that I might be choking it with the shorties. Opti is newer, plugs are new, wires are good. Car runs great in general.

not too bad for stock ported heads and that cam

i dont think the shorties are the issue, i've made more power then that with the same headers.
what type of dyno was it? have you ran it at the track to see what it traps?
both numbers seem at least 30 low, not sure how much cats are going to choke it up. i had decent heads and same cam and dynoed 390/360

I think u can go leaner at wot...

leaner is meaner.... ;) j/k

MEMBER @ LTXtech.com

Might actually try richen it up to 12.2 or 12.5 what timing?

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Originally Posted by Dangerous95lt1

Might actually try richen it up to 12.2 or 12.5 what timing?

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on a serious note...wasnt it like 11.5 that was the prime na wot a/f?

MEMBER @ LTXtech.com

That's way low. More often than not a CC306 cam only car will make around 360 RWHP. N/A you want to go about 12.8-13.0 AFR at WOT, for the "sweet spot" per se.

I was shooting for 13.0, ended up a bit over around 4-5k. It's not exactly dialed in, but I didn't expect it to be THAT low on the dyno. Timing is aggressive, but zero knock. I don't have the tune in front of me so I don't have the numbers. I suppose it's possible the guy I bought it from was full of shit and these are just factory heads. Would it even make this much power with this huge cam and untouched stock heads?

Leaving a lot on the table. My wifes TA with simple bolt on's and stock internals put 339 to the tire. All she has is 1.6 rockers, shorty headers and a cut out and a gear. Nothing else. All I did was tune it. You should be in the 360 neighborhood with a good tune. I was actually shocked to see your hp number and being 1 off of her car and hers is an auto. Here is the dyno from when I tuned it for the previous owner of the car right before we bought it.
http://i3.photobucket.com/albums/y77/jpack24/KIM.jpg

My car cc306 car. Picks up a full tenth at track between 13.0 afr and 12.4. N/A runs 8.03 with 13.0 and 7.93 with a lil richer 12.4 afr. 1/8th mile times. AEM wideband

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We're street tuning it so I can't confirm with actual numbers, but it felt like a monster at 12.9-13.0 vs mid 12's. Night and day difference when we leaned it out.

How much timing you running?

I'll have to get the tune in front of me, my friend has the tuning laptop at the moment. It's aggressive, but doesn't knock at all. What kind of timing do these cams like? I assume that as long as it's not knocking, I'm not going too far?

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Originally Posted by Mr. Brett

I'll have to get the tune in front of me, my friend has the tuning laptop at the moment. It's aggressive, but doesn't knock at all. What kind of timing do these cams like? I assume that as long as it's not knocking, I'm not going too far?

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sometime you can get more power out of it with less timing, and a leaner afr. i think i was running around 34-35 degrees on 93 octane.

i'd like to see your tune and datalog if you have them.

I'll get a copy and post it.

Car was running 34-37* at WOT, 12.7-13.0 AFR

I took the car out for a bit yesterday in the early morning when it was nice and cool, and the AFR was as low as 12.6 at times. I think I might need to do some more MAF tweaking and dial it in a bit. I'll make some changes this weekend and get a tune and updated scan posted. Thanks everyone for the feedback.

you tune to what the car wants, every set up being the same are different, looser tolerances in the motor, factory balancing, carbon build up ect. I have had two identical cars, basically the same mileage, same cams ect, put them on the dyno and one would like a richer A/F with more timing and the other Leaner with less timing, One made 20 more RWHP. Back in the day Chris Bennight was the LT1 Guru, he had a cam, bolt on only, M6 with a lot of gear and ran high 10's, Very aggressive tune, 39* total timing up top. Again, I tune to what the car wants, of course check your plugs for timing marks, heat ect..

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Originally Posted by Mr. Brett

338/326


Note: I bought the car as it sits and have only tweaked the tune, so I don't know the exact flow specs on the heads. Stock bottom end, 119k. AFR is 12.9-13.2 at WOT. Thoughts? This seems awfully low compared to what I've seen from this setup. I have Edelbrock shorties, a high flow cat and an unknown catback (Magnaflow I think?). Peak torque came on at ~3k and stayed there, power climbed until redline. One theory is that I might be choking it with the shorties. Opti is newer, plugs are new, wires are good. Car runs great in general.

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Did you really only take it to factory redline of 5200rpm or was that an expression? That cam wants 6700. What springs are on it? Could be valve float, can you post the graph?

isnt factory like 5750 or something like that.

^ That's what I thought, factory gauge shows redline about 5700 RPMs.

5749 was factory set in my tune as rev limit but i haz autocraptic.

Sorry, meant to say the limiter. It was revved to 6500, don't want to spin a bearing. Bottom end is stock.

My wife's car is a bolt-on (LT's, 1.6 rockers, EWP, 36lb injectors) with a 306. Other than the rockers the heads are completely untouched put down 351/351 only taking it to 6000. A good tune is where a lot of it is at.

Seems like the LTX cars like to be a little richer than the newer stuff. I have seen 2-4 tenths of track time gain from 13.0 WOT to 12.2 in a couple of the heads/cam cars I've done. I would definitely go a fuzz richer and stuff some more timing in it if you can. Mail order tunes are usually 35-36* of timing, so you can sometimes get another 1-2* in and make more power. Just depends on the car. While a mail order tune gets the car running OK, they leave a LOT on the table.

I would also go to a NGK TR6 plug with your setup too. Especially if you run a 160* thermostat. Going to a colder heat range seems to be a good move with most heads/cam cars, even without nitrous.

What valve springs,rockers, pushrods are u running? Run a fuel pressure test, just for kicks?