Well, I finally got around to getting another dyno done after fixing a couple of things on the car. The first thing was putting in the LT4 Knock Module in place of the LT1 module that came with the stock ECM. Once again I really don't understand why SLP left the stock ECM (including knock module) in these cars when they put in the LT4 engines, but it sure makes for a nice change when you "fix" it. I also had been hearing a "ticking" at startup over the last month or so, and when I finally got a chance to check it this past weekend I discovered a couple of loose exhaust manifold bolts on the driver's side. I don't think the exhaust manifold bolts were loose when I did the previous dyno, so at this point I'm going to say that the big gain over last time (11RWHP and 8TQ) came from the LT4 knock module. This would tend to hold up as I was seeing some knock retard after the last dyno run when I did some monitoring using Datamaster. After retightening the manifold bolts over the weekend I am now seeing ZERO knock retard (both on the dyno and on the street). So, the final gain from the ECM tuning and LT4 knock module at this point are:
29RWHP and 21TQ

This now puts flywheel HP at 366HP, and I'm hoping to increase it a little more as the car is still running a little rich (about 12:1-12.5:1), and by adding a few mods. My goal at this point is to get to 330RWHP so that the 330 HP stickers on the hood actually match up to something!

Once again, the only difference between dynos is a tuned ECM and the LT4 knock module, everything else is stock:

 

That's strange that SLP didnt put the LT4 KM in those cars, but then again if they left the stock LT1 program in the PCM I guess it's not that unusual. You would think they would have just installed an LT4 PCM in there while they were swapping the engines. Very nice gains you picked up with the KM and programming, I cant beleive SLP left all that power on the table with those cars. I bet a hotcam would put you well over that 330rwhp mark

 

nice gains

 

Nice gains.

Better update your sig.

 

Nice dyno... those numbers are almost exactly the same as those INTMID8's LT4 SS put doen after he tuned the PCM. I wonder what the LT4s will do with some boltons..... headers would make a huge difference. Will the LT4s put down around 350rwhp or so with all the bolt-ons? (headers, electric WP, 1.7RRs, etc....)

 

Done. Thanks for reminding me.

I guess we might have to find out. After the run we compared it to the dyno from the shop owner's LS1 WS6 afterwards, and it had noticeably better torque on the low end. We also compared it to a WS6 TA with the LT4 conversion (w/ hotcam) and they were very similar (within 10HP) to about 4600, but then where mine starts to drop off the hotcam LT4 kept pulling in a straight line to 5900 (where they stopped) where he had 347RWHP. If I remember correctly he had headers and was running an open cutout. Here's the link on his graph:
http://www.tulsadyno.com/customers/C...DynoGraph1.jpg

Anyway, my plans at this point are for an offroad pipe (mainly for sound, but hopefully for a few ponies too), maybe a 52mm TB, and then I'll decide if I want to do headers or a cam I'm leaning more towards doing the cam before the headers just to see what I can get without headers. Plus I can't go long tubes as I don't want to loose any ground clearance, so if/when I do headers I'll probably do a 94/95 style header conversion. I know it's a long shot, but I'm really hoping that with offroad pipe and 52mm TB I might be able to hit 330RWHP and make the numbers on the hood match up with something.

 

You should consider a true dual setup. I got 12 rwhp over the
3" cat-back system. It's expensive but a lot better than dealing
with headers in my opinion. Now if you wanted 350+ rwhp it
would be a different story.

 

I might have to think about that. I saw the pics of your setup and it is amazing. Can you email me all the pics you have and all the iinfo on it? I might run it by the guys at the shop I get all my work done at. They do a very good exhaust work and could probably duplicate it.

 

Will do after work. Most of my files are at home. I need to put
together a summary of the project anyway. Send me an email
as a reminder to respond with the goods.