It was a typical late night for me working in my shop at the house when my cell phone rang just after 10 PM yesterday evening. Turns out it was a phone call from my friend George Lara, a respected tuner in the So Cal area and an all around good guy. I had been waiting for this call for a few weeks, not to mention this project originated almost 6 months ago, but isn’t that par for these types of things anyway.

Back in April I had gotten involved with a C6 project belonging to Greg Schult….seems Greg and his brother Alex are somewhat competitive and with the two of them recently purchasing C6 Corvettes, the stage was set for some power mods to up the ante. Alex went the Magnuson forced induction route and put down some respectable numbers with basically the stock C6 short (490 RWHP / 490 RWTQ thru an A4) and Greg contacted me inquiring whether we could come close or possibly beat those figures with an N/A build. Initially we had moved forward with a package designed to optimize the stock 6 litre block in his car but somewhere between the start of this project and his brother on the dyno….LOL, Greg decided to get with LME on a 403 stroker to make things more interesting. Besides spec’ing a larger cam, most of the work on my end remained the same. We used a set of 205’s that I opened up the chambers and did some light porting work to optimize their small efficient ports (like I helped Pat G. and a few others with), ported a FAST and an LS2 TB, and sent him shopping with a list of the other supporting mods in the recipe (Yella Terra rockers, EWP, lightweight clutch, etc. etc.).

I was hoping to see around 525 RWHP with 500 TQ, and felt if everything really came together there was a chance it might make a little more. BTW, with a set of 1.875 Kooks headers already installed on the car (and a CAI as well I believe), on the same Dynopack wheel dyno over at Haddad Motorsports where the tune and the install was performed, the car put down 375/375 as a baseline prior to the engine swap. Pretty much solid textbook numbers for 364 CID engine and an M6 driveline with those mods (similar to others I have seen). The baseline dyno graph is included below to compare the data and shape of both curves….

Here are the final results….



I was especially surprised and pleased at how well the TQ curve carried without the band-aid of a monster sized cam which would have obliterated the bottom end and hurt drivability, essentially getting away from the well rounded package I was shooting for. While this technically isn’t an out of the box 205, the finished port volume is within a couple of cc’s of that showing once again that “area under the curve” flow coupled with good port velocity and a well thought out combination is more powerful than most realize. Picture the throttle response this animal has with all that power and a tiny 205cc intake port….its a lethal street combination.

This car made over 550 RWHP on five consecutive back to back runs (500-503 TQ) with the best registering 558 at an A/F ration George felt was a touch aggressive (13.7-13.8 over 6K), so he fattened it up a bit to give Greg a little more hip room on the street. Down in the low 13's the car still rolled 552/500 with a much more conservative A/F across the curve.

For those interested here is the flow data from Greg’s 205 heads tested on a 4” bore (on May 2nd no less!....lol)

Intake
Lift…..CFM
.200…..151
.300…..220
.400…..266
.500…..293
.550…..302 (peaked at .575 @ 306 CFM)
.600…..301

Exhaust (w/ 1.875 pipe)

.200…..129
.300…..190
.400…..228
.500…..242
.600…..248

Note how strong the exhaust port flows after the chamber and light porting work….It’s close to 200 CFM (more than a stock head’s peak flow) by .300 and as early as .400 matches a lot of aftermarket heads average .600 number at 228 CFM. Due to this situation and the very high overall exhaust to intake ratio (82%) a single pattern cam (244/244) was obviously a good choice here and proved effective on the dyno.

A quick summary of this combination is as follows because I know a lot of you will be asking…

403 Shortblock (built by LME)
11.6 CR
AFR 205’s with reworked 4” bore chambers and some light porting in key areas
Ported FAST 90 / Ported GM LS2 TB
Custom Comp Cam 244/244 XER lobes 113 LSA
ASP Underdrive pulley
Mezeirre EWP
Kooks 1.875 headers (with Cats btw!)
QuarterMaster clutch/flywheel assembly
M6 driveline with stock rear gears (3.42)
SVO “green top” 42” injectors
Vortex Ram air CAI (85 mm)
Nology ignition wires

Thanks to LME for all their hard work on the short….Mike and crew @ Haddad Motorsports for the install and “storage”….LOL, and George Lara who put all the pieces together with a killer tune. Look for some idle clips and video footage of this combination in the near future as well as an article in one of the Vette specific Mags….

Regards,
Tony Mamo

 

So much for needing bigger heads with bigger cubes. BTW, your graph is not posted correctly. All I see is a red x.

 

That's some killer top-end for little heads. Nice combo!

 

Really Nice combo. Someone should be very happy with the performance.
Congs

 

Not only 550 hp, but at 6,200 RPM

 

Hey Tony, I'm looking to get a set of heads within the next year. I want something that keeps stock compression ratio so that I could go with a blower if I chose, but I also want a head that will work decentlyl if I decided to stroke the motor instead. I know that some work will be needed on out of the box heads for that, but minor work isn't a big deal, I just don't want to have to buy new heads if I decided to stroke it down the road.

Will these heads work for these goals? From the post above it seems like it.

Thanks!

 

Wow, that combo seems to work beautifully! Well Done

 

Just drove the car this morning.
All i have to say is wow.

For all the east coast guys thats 91 octane.
I wish we had 93 I'm sure we could have pushed it a lil harder.

Thanks,
Mike Haddad

 

very nice results

 

Wow tha has to be one hell of a ride.

 

Somebody explain why at the bottom of the graph it says torqueflywheel and powerflywheel, and the printout on the right side of the graph says flywheel?? Flywheel and rwhp are different? Yes, No???
Thanks.............

 

GREAT JOB TONY

 

Wow guys. Great combo. Tony those little 205's have done it again...

I may have to reconsider my 383 build. It came with a 97 block and I'm not real thrilled about using it for the build. I could ditch it and get a 6.0L block and different pistons to build a 402. Hmm.

The only thing that scared me was I already have the 205's and did not think they would do well with the bigger cube motors.

 

Freaking great numbers.

AFR and Tony

 

Tony, again nice work on another project. This is quite possibly the highest N/A Gen3 40X setup that I have tuned, possibly the shop as well. I knew we were going to hit 550rwhp after the first pull with only a simple starter tune, which put down 541 rwhp on a 12.7 AFR and 17 degrees of timing. Greg took it for a simple test drive after the tune, he had virtually no traction in 1st and 2nd gear with very moderate throttle. That is one awesome ride! Gotta love those 205 AFR heads.

Easy! Dynapack dynos measure actual rwtq at the axle (unlike a dynojet, which has to calculate rwhp, then calculate rwtq based on that and rpm), to get internet comparable results you simply divide the actual rwtq numbers (that graph is not shown, but the actual rwtq numbers were 1710lb/ft) to get more common known values. Since these calculated values are not true rear wheel numbers, dynapack list it as flywheel numbers. Since we do not know the drivetrain losses, it can't take that loss in to account, so the results are labelled as such. The true torque value of 1710lb/ft is the "real world" torque that moves a vehicle due to the differential gears multiplying the torque (3.42:1 axle:driveshaft ratio). Welcome to the real world.

 

FANTASTIC

 

Very nice numbers fellas!

 

I would have personally done a 402 build from the start. I have no doubts that the 205's would work well for what you are after. Just remember you should have more tq with the bigger motor as well.

 

Well Tony, you have done it again !!!

That car must be a monster on the street. Congrats, and I wish you much success in the future.

 

Awesome results Tony.