A little bit about the setup. Previously I had a head/cam vette that made 460whp. I decided to build a 403ci motor because I love the all motor vs blown applications. The sound is intoxicating and the reliability factor was key for me. I previously had built a 408ci motor for my GTO that was more a race motor than a street motor. Ultralightweight rotating assembly,clutch,flywheel,wheels,etc. made 550whp but made it a bear to drive that 4000lb car on the street. Ok, onto the Vette buildup.

Bottom End:
LS2 403 built by LME
Blueprinted/balanced
Cam Motion 244/250 .643/.645" 114LSA cam 110ICL
Callies 4340 crank
Compstar rods
Weisco nitrous forged pistons
LS7 lifters
Mellings oil pump
Double roller timing chain
ARP everything
Underdrive pulley

Top End:
AFR 225's (62cc)
w/8019 springs (150 seat/ 440 open press )
Cometic gaskets(.051")
11.5:1 Compression
SVO 30lb injectors
Stock Rockers
Callaway wires
TR6 plugs

Induction:
Mamo Ported FAST 90mm intake
Shaner S2 ported TB
Callaway honker intake
Stock descreened MAF

Drivetrain:
Textralia OZ700
Steel flywheel
3.91 gears
LG Motorsports World Challlenge wheels 305/30/19"s

Exhaust:
American Racing 1 7/8" Headers
3" Xpipe w/ cats
Borla Touring exhaust (2.5")
QTP 2.5" cutouts placed by rearend (still goes through cats)

The car got a base mailorder tune from Charlie Williams @RPM. I asked him to setup something safe while I broke in the motor. The tune was pretty darn good and started the car right up and got fueling within 7% all over from 3000 miles away. Kudos to Charlie. I did some final power tuning as the car was very rich.

The first pull on the dyno netted 470whp/410wtq. The car was very rich and timing was very conservative at about 18-20*. After dialing in the a/f the final numbers were 491whp/443wtq. This got the timing aroud 24-26* (all it could sustain safely) and the a/f 12.8-13.0. I was very happy.

However, I had two issues to address. The first issue is that while at the dyno I noticed that the map readings from approx 4000rpms and up were between 98-96kpa. These meant there was some type of restriction up stream of the intake. I was running a Vararam intake on the car. After leaving the dyno I did some WOT pulls over the next couple days and the map readings on the street were 97-5kpa between the same 4000rpms and up range. After doing some research I ditched the Vararam for a Callaway Honker. After getting it installed the first couple of pulls on the street had the map readings from 99-100 and never going less than that. I was very happy to see this and noticed the car felt quicker up top.

The second issue was the exhaust system. I know running cats and the touring style exhaust was hurting hp. I didn't want to take off the cats for anything, although I wanted more hp. After talking with Joe G. I found out I could have my cake and eat it too. I had a set of 2.5" QTP electronic cutouts welded downstream of the cats at the rear of the car. I would have done this mod for the sound alone. However, uncorking the intake/exhaust paid big dividends. The highly calibrated butt dyno said the car was much faster.

I took the car back to the dyno for some more pulls. After re-dialing the a/f back in I was able to add another 2* of timing due to the better flowing exhaust. Final timing was 28* down low 23* at peak tq and 26* at redline. Final numbers 515whp/465wtq!! Needless to say, the car is flat out amazing. It makes 500whp or more from 5700rpms to the 6700rpm shift point. Below is the hp graph posted with mph. Using engine speed caused the curves to be broken and the tq curve is extremely jumpy due to the noise from the cutouts. I know there might be more power in it by removing the cats, but it is so stealthly now at highway speeds with the cats/cutouts closed I wouldn't change it.

The car goes back to to the shop this week for a 150-200 shot of nitrous courtesy of Dave's Nitrous outlet. I'll post back with results.

Ok, I've posted several graphs below. I couldn't post the tq curve because it looks all screwy, so only HP curves

This graph is from the first pull with the 403 to the final tuned numbers with Callaway Honker and Cutouts open and through cats.


This one is of the Vararam/no cutouts VS. Callaway/cutouts open

 

Glad to hear its going we`ll. Nice set-ups!

 

that calloway is a lil pricey isnt it.i was thinkin bout ditchin my vararam for that.

 

I only did it because it showed a restriction. On the C5's isn't the Vararam have twin openings?

 

Nice numbers. Doug, what car is faster, your vette with these numbers or your GTO when it was making 540/475??

Are the AFR's stock outta the box?

I always thought the vararam was the best CAI for the vettes.

 

Doug, the graph looks nice and I'm glad to hear the car is running strong.

We need to get together, dyno, compare build notes and run the cars...

I kinda went on the small on my build with the heads/cam(ETP 215's/G5X4) so I would like to see how it stacks up against a larger head/cam 402....

Alan

 

Good write up and congrats on the result.
Is the Shaner TB 90MM ??
Enjoy it.

 

My vette is much faster. The weight of my GTO with subframe connectors and the iron block etc was 3820lbs. I'm 205lbs. LOL...heavy.

The vette checks in at 3165lbs. Roughly 650lbs lighter in the vette.

The AFR's are box stock 225's with upgraded 8019 springs.

The Vararam is one of the best intakes out there for the vette. I just wish the quality was a little better.

dougie