Do you know what valve springs they used?

 

So i picked up the car...and it runs great...but back to the question at hand: Here are a few more specific parts that have actually been used:
-all the forged stuff mentioned in original post
-30lb injectors
-1.6 Crane Roller Rockers
-Crane Push rods
-Comp Cams Springs & locks
-ported stock TB & intake mannifold
-Manley SS. Swirl polish race valves

I also have a dyno sheet, but I don't have a scanner so i'll try to describe it a bit. The tq band basically jumps from starting at about 2500 rpm to it's max (364rwtq) and stays there all the way across the board. It only starts to decrease a little starting at abotu 4800 rpm. While the HP curve gradually climbs over the rpm range and finally peaks at around 5400 rpm (339.5 rwhp). So is it possible that they just tuned it to maximize the torque across the board...(in a sense making it more "fun" for daily driving)?? Could adjusting the tune really pull out another 40 - 60 rwhp...putting me in or close to the 400 rwhp range?

They didn't give me the flow numbers for the heads...but I'm gonna call them up and have them email me the info, along with the exact cam that they used...that should help determine the short comings of this build.

Injuneer:
Could you give me info on that shop?

Thanx for all your input...keep it coming

 

hmm i would think that with the cc306 your HP should be peaking at a higher rpm??

 

your first mistake was taking the car when you weren't happy with it...now that they have your money and the cars gone they really have no motivation to get it fixed if they don't care about reputation...

You should have asked/been provided with fllow data on the heads a long time ago, before they even assembled the motor. You may not get any now...

 

Maybe they just used the stock cam?

 

What is the comp. ratio? You mentioned that the business had "Supercharging" in their name....Did they build you a motor that they thought was to be supercharged in the future? If so then you could be running a static compression ratio in the 9.5:1 range that would definately lower your NA horsepower, but increase your ability to run GOBS of boost.

 

Did anyone not see he mentioned the stk TB? That's part of your problem right there. You are choking that thing. At a mininum go to a 52. Got all that money invested and from what it sounds like a pretty good setup. Why short change the breathing of the heart itself.

 

I think you said at the beginning of thepost that the compression ratio was 10.3 or 10.4. That would kill horsepower if you werent supercharging or turbocharging the motor. It sounds like they built you a forced induction 383, and as before mentioned they had supercharging in their name.The compression ratio is what is killing that motor, because the ratios you stated is not much more than stock. Go back there and chew some a@#

 

Second Street Speed is in Perkasie, PA. They have probably built as many 1,000HP LT1's as anybody. They aren't real big on tuning stock PCM's though, since they are authorized installer/tuners for MoTeC, FAST. ACCEL/DFI, etc.

I disagree that the compression ratio is killing it, if it is 10.3-10.4:1. My 381 runs 10.8:1 and with a very mild cam, made 425rwHP (when it was an M6). You might be looking at picking up maybe 2% on power by running at 11:1, compared to the current 10.4:1. No biggie.

Also not sure the 48mm TB is a big problem... GM seems to think they are big enough to support their 502ci/502HP Ram Jet big block crate engine. My 58mm reached max flow at only 77% throttle opening when we were tuning it on the engine dyno.

Maybe its a combination of a lot of things, each one sucking out 10 or 15HP - tuning, CR, TB, heads, etc.... and costing big power when you add them all up.

 

Man I hate to hear this kind of stuff because I have been in similar situations myslef. You need to go talk to them face to face very politely and tell them you are disatisfied and that this is not what you expected from them. Convince them that this is hurting their reputation and that they should get it running right for you. I really hope everything turns out all right man. And find out what exactly is in it, you mention 306 cam and then you mention that you arent exactly sure on what cam is in it. That makes a HUGE difference. Goodluck again.

 

They didnt use a mustang dyno did they?

 

I had a talk with them when I went to pick up the car. I told them that many ppl on this board have hit over 400rwhp or at least close to it with a similar setup or simply a good set of ported heads and a cam. I also asked about the compression ratio, they said it was 10.5 which is about the same as stock. It was originally higher...but they mentioned something about bringing the CR back down a bit when they ported the heads(i'm not familiar enough with that stuff)

Basically this is what they told me while i was there: that to have the car running at that power level it would become a high maintence car...increasing the CR into the 11s would require more octane and that I would have to put in a fuel additive basically everytime i fill up on gas. Also that these 400+rwhp LT1s might be track only cars or weekend drivers making the higher maintenance less of an issue. They said that they built my car to be very streetable to run on pump fuel...etc. They also mentioned 1 very invalid point: 1. the 400rwhp is the peak and those cars only reach that peak for a second or 2 at high rpm...isn't that where most ppl reach max power???

Anyways...i didn't want to be an a** about it because I don't have all the answers...like I didn't know whether the other 383s were high maintenence, trailer queens or daily drivers like mine...So if you have a similar setup, let me know what the car's main purpose is.

As for the "supercharging" being in the name...true they do a lot of FI work, but I went over with them what i wanted before the build began. I told them that I wanted it all motor...and a pretty aggressive daily driver....and for FI, i would think the CR would be down in the 9's (I could be wrong)

I'm bringing the car back there within the month anyways...I'm breaking in the engine right now and they said to bring it back after I hit 500-600 miles so they can change the oil and put in synthetic. So in the meantime I want to get as much info as I can, so I know what to have them do.

Cam specs: 540/220/230 112
as for the heads...they were hand ported and he said they usually flow about 255-260...(no flow bench...so I can't do anything about that)

Again, thanx for the input & advice...keep it coming...i really appreciate it. ALso if anyone else has had experience with East Coast Supercharging...please chime in.

 

Your cam is holding you back a bit as well, my 383 is daily driven and gets 18 mpg on 91 octane with 11:1 compression.

I started with a 224/230 cam in my 383 and it would only trap in the 109 mph range (3750 # car) I later changed to the GM 847 and now I trap in the 114-115 mph range . I havent dynoed it yet , but thats very close to 400 hp according to NHRA equations.
I weighed the car both times I was at the track and both times it was the weight mentioned.
The torque the car has is unbeleivable, anything below 45mph and you punch it and you lose traction to the point of tire smoke.

I'm sure there are some strokers on this site that could hand me my butt, so I'm definately not on the high side.

 

Is you car a daily driver?

 

Doesnt seem to me that they have a ton of LT1 experience for street cars. Yeah, they may build 1000hp LT1's, but if cant get a street machine right...

My problem is they dont know the streetability of a 400rwhp motor. There are a ton of guys making more power than you and they run stock bottom end (350c.i.) and daily driven. Look at my numbers. You made a little more torque and I made alot more power with smaller cubes. Mine is streetable. I would be dissatisfied for sure. Another problem is you let them pick your cam. You should know us board members would have given you better recommendation. You have a baby cam in a a stroker. I am surprised they didnt just leave the stock cam in.