I just installed stage 2 ported heads from a very reputable board sponser as well as an XE230/236 cam. The heads have 2.00 intake / 1.56 exhaust valves, titanium retainers and guide plates. I'm running CC 1.6 rr's, double valve springs, LT4 Extreme timing chain, stock style roller lifters, MAC shorties, SLP 2OTL exhaust, vigilante 2800 stall, ported MAF ends, 30 lb injectors, 255 lph fuel pump, NGK TR6's (future nitrous plans) blah, blah blah, etc., etc. I kept the stock unported intake.

Anyway, I took the car out to the track and ran a best of 12.45 @ 109.8 mph w/ 1.76 60 ft time. Conditions weren't ideal either in the track or the weather, but I still can't see me trapping much better than 111 mph even on a good day. WTF is wrong? I even had the car dyno tuned at a reputable shop. NO knock retard at all at 36* advance and 12.4 A/F. Dyno numbers aren't even worth mentioning. The car fell on it's face at 5500 rpm on the dyno. The theory was I was blowing out the spark because I didn't have my MSD on yet??? I installed the MSD before the trip to the track. This is a car that ran a best of 12.85 @ 105.1 mph with just bolt ons. Granted, it's a convertible with an 8 point roll bar and subframe connectors, but it also doesn't have carpet back in it yet and I removed the A/C compressor when I did the heads/cam install.

Any suggestions? Like I said, the heads are from a reputable company and looked really good!?!

 

whos heads? maybe you should talk to them. cam installed propperly?

5500? that cam pulls like a stock cam....

 

Trey - The heads are from your sponsor. I really don't think the heads are the problem, but who knows? As for the 5500 rpm thing, I should have explained it better. The curve goes up as normal. At about 5500 rpm, the It drops sharply and then comes back up at like 6200 rpm and fall off as normal until the 6500 rpm rev limiter. I guess this is what led them to believe it was the stock ignition. Like I said, there was NO knock detected and no knock retard. The curve kinda looked like it was breaking up in that rpm range but the car didn't really sound like it was breaking up.

The water pump took a **** on the way home from the track so maybe I'll put a new Opti on there when I replace the water pump. The other Opti was a rebuilt that I sorta accidentally bought on Ebay. I was gonna replace the water pump as maintenance but didn't because last time I replaced a factory part with a rebuild as maintenance, I wound up replacing it 4 more times in the next year!

Edit: Actually, I need to give Seth a call tomorrow. I never got flow bench numbers with the heads so I have no idea what they flow.

 

Hay Scott don't be bummed you have more in that combo. I now we talked before but you were stk now we can tweek
I'd start by running some good gas and putting some timing in that thing. 36 is low
I'd start at 40 and don't be suprized if you still see gain's at 44 deg.
Trust me here Lt1's need timing at wot on a na combo, these heads are not as good as a LS1 fast burn.

Now the heads , one question...
how much was cut off them or better yet what cc did they cut them down to?
If your just dealing with a clean up cut your not going to see any gain in the quench area. Now if you are willing to pull them off and cut them down to 52 cc and cut the intake to fit correctly you will WAKE that motor up!!!!
E-mail me and I will send you a tune that will be on the rich side and you can lean it down from there, but you will have to run like 2 gallons of 110 leaded to a tank of 93 unleaded or 100 unleaded will do.

 

Jeff - At the time of my dyno tune, additional timing didn't help any. I didn't have the MSD on yet and the thing was dying at 5500 rpm when it should pull peak HP at 6000-6200 rpm. Maybe now that the MSD is on, more timing would help. Also, it was tuned with straight 93 octane.

As for the heads, they are Combination Motorsports stage II heads. I have the following information on them:

* 55cc combustion chambers + Fel-pro 1074 gaskets = 11.04 to 1 compression

Flow numbers:
Lift Intake Exhaust
.300 201 138
.400 243 171
.500 262 190
.600 278 198

They agreed that I was definitely down on power and offered to help figure out what the problem is if I could send them the wideband info. I honestly don't remotely suspect a problem with the heads. They looked great. Granted I didn't flow test them myself but I trust Combination Motorsports. They seem to be very reputable and I've never heard anyone say anything bad about them. So far they've treated me great and have been nothing but accomodating. I have to believe the tune is at least close, though maybe it could be more fine tuned if the MSD fixed the problem we were seeing at 5500 rpm.

I'll send you an email. Thanks for the help!

 

What plug gap are you running?
I'm running .040 on mine, have the same setup as you.
We found out on the dyno at the higher RPM it started to miss due to the spark getting blown out.

Mine made power all the way up to 6500, and I think at one time we ran it up to 6700 just to see.

I agree something is a miss here, My car on a bad DA day we are talking 3000+ with humidty in the 75% or more range the car still goes 11.90's at 113mph.

 

I'm running TR6's with .037 gap. The guy doing my dyno tune also said he though I was blowing the spark out. He told me it should be okay with the MSD on. I added the MSD Digital 6 before going to the track (after the dyno tune) and only pulled 110 mph. Maybe my MSD is bad? I bought it used but it was fairly new. What did you do to fix the problem? I also have the MSD Blaster coil.

BTW - I'm shifting at about 6300 rpm. It's hard to tell exactly in first gear because I'm running the stock tach which is horribly inaccurate. For some reason I can't get the LT1_edit scanner or free scan to work which would tell me what rpm I'm at. They both just create empty data files. I was going to try Datamaster. Unfortunately I won't be home for another 2 weeks and will need to replace the water pump before I can log any runs.

 

Wow I would be pretty dissapointed also, it sounds like it could be your spark blowing out, but can't really tell. Did your TQ drop at the same spot or was it just the HP? This is really wierd I personally have never heard of anything like this. Be sure to let us know what fixes it so we know what do to. Good luck!

Ken,
How did you like your Fastchip tune? What kind of increase did you see before you had the tune? I am scheduled to get mine from him this winter, I still want to do it, I'm just wondering how it was for you.

 

Don't know if it's related to your problem, but I would probably close up the plug gap to .40 or less and also go one heat range colder if you haven't already. Bag the ported MAF ends cause their nothing but trouble unless you do your own tuning and your a MAF table God. I just bagged mine and it runs a lot better. Also, try leaning it out if you haven't already. I know every car is different, but mine made the most power at about 13:1 and I used to run it in the mid to low 12:1 range before going to the dyno. There may be a little more in it, but that doesn't sound too bad with your setup. Kinda hard to judge because im up at 5200 ft altitude so i'm used to gettng wacked by about a second from sea level. I'm running a similar setup and run 13.70's up here but thats with street tires and 2.2 60ft's. A set of slicks and running at sea level and I would figure it more like low 12's. You shouldn't be seeing that drop off though thats weird. Should pull hard all the way through. Anyway, just some input. Hope you get it figured out.

Ken R. 95Z

 

I would suspect yor opti or wires first. Also check your rockers. Loosen them up until they make a little noise when cold. Zero lash plus 1/8 turn cold. I lost about 40 HP when my rockers were too tight. Your setup isn't too far different than mine and I pulled up to 6400 and it was still climbing.

Good Luck

Steve

 

Who did the tuning? I really doubt that the heads are the problem. Also don't get discouraged your first time out, with a little more tuning and getting the bugs worked out will make it a different car. My car was running 13.0-12.9 right after my heads cam setup, I'm almost a full second faster now with the same heads and cam

Also when the heads start flowing the weather makes a HUGE difference on a NA car. My car runs about .8 slower in the quarter in 100* weather vs 50* weather, a good 5-6 MPH less too.

 

Love it, we did at least 10-12 pulls on the car, he was constantly changing values to get the car to run. Another plus for me is that he is in my home town, he meets me at the track some time and we do some tuning at there also.

Ed just got done building a 355 with a very mild cam and it put down 385rwhp through an A4, torque was 390rwtq.

 

I don't think it's running bad at all. In less than ideal conditions, my times can range from 12.4s to 12.9s. I too have a heads/cam package with a raceweight that ranges from 3670-3700 depending how much gas I have or if I'm running the skinnies. Even without the ac compressor and the seats, I'm sure your car is still heavier than mine with your cage and convertible equipment. What is the lift for that cam and was it recommended by combination to work with your heads? How much power did you make on the dyno?

 

Yes, Combination recommended the cam. I have faith in them and still do. They've been nothing but helpful so far. The lift of the cam is .510/.520 with 230*/236* duration on a 112 lsa + CC's standard 4* advance in the grind. The car made 320 rwhp on a Mustang dyno.

The Opti was a rebuild so I thought that might be a possibility but people that have seen the graph say its not the Opti. Also, the rockers actually make a little noise even when warm so I doubt the lash is too tight. Maybe I'll recheck them, though. They don't make enough noise to trip off any false knock.

 

I didn't have MSD and my car pulled strong, so I dont believe the blowing out the spark bit at all. If you didn't get your heads flowed independantly, IMO that shows up the truth behind someones work sometimes. My heads were very close from the porters bench, to one down all the way in southern California, almost identical.

Tuning could also be another issue. IMO though there are alot of dishonest porters out there, I like to check independantly. 5500 RPM could be an ign miss, bad timing, or weak valve springs. If its a weak ign check the resistance of the coil and your ground strap hookup.