I have an 03 C5 with a Procharger (7lbs boost), American Racing headers and x-pipe with SLP loudmouth. Yep bought the vette with the Procharger already installed but have been babying it (kept below 3500 rpm) until I had the shop take it in and install the headers, x pipe and exhaust. He found a few minor issues and prophylacticly addressed a couple others (swapped oil pressure sensor).

They are buttoning a few things up and I should pick it up tomorrow. He did send me the dyno numbers and I must admit I was disappointed, I had hoped for 550 range. 468 hp/426 torque. Am I wrong, should it be more?

 

What fuel?
I think i made 456hp with an SI on 91, cheap headers and axle back. After a cam and meth I made 630hp.

 

It’s on 91. I was hoping that the Procharger and full exhaust would have brought me over 500. So I guess now it’s time to start a heads, cam fund, might as well add clutch fund and go for bigger numbers b

 

heads and cam will be expensive way to add those ponies. Look to e85 and pulley down and 600 awaits.

91 is no bueno.

 

No true availability for e85 around here. I figured a smaller pulley would help.

 

What kind of dyno what's used? Mustang, dyno jet? Get it to the track that will help like others have told me. But I agree go up to 93 if you can first. Did they look at the tune?

 

Dyno jet. Yes he worked the tune as well. It started at 431 RWHP and 388 RWT after the header install, after the tuning it is now 468 RWHP and 426 RWT.

 

Oh wow I made 440rwhp and 403ftlbs with just heads cam intake and full exhaust. I have supporting mods to help get it their like porting the fast 92, the LS2 tb is slightly Ported. I need to have mine retuned. But yea those seem slightly low from most of the numbers I have seen. But with 468 to the rear I know it's fun to drive!

 

I haven’t picked the car up yet. I’m hoping it’s ready for pick up today or tomorrow.

 

the tuner is likely conservative on boost and timing due to the low octane.

if 91 is the best you can get, might be an issue. I like to stay far away from detonation with the hyper stock pistons

they micro fracture from detonation and then let go with rather spectacular results. Ask me how I know.

 

Yeah if everything is in good shape, those numbers are super low on a Dynojet, even on 91. You didn't mention if this was an auto or 6 speed, but autos will usually read lower. Not THAT much lower, but lower.

What head unit and pulley size?

Did he mention anything about running out of fuel or having fueling issues?

Do you have the dyno sheet? If he shut it down at 5500rpm, that may be a good reason too...lol

A base/standard A&A kit with the smaller si head unit and 3.8" pulley will safely get you 500whp on 91 in an otherwise stock 6 speed car, 9 times out of 10. I think expecting 550 with just headers is a stretch on 91, probably should be closer to 530ish.

Without knowing which procharger head unit and pulley size though, hard to compare.

I'd get this resolved before throwing heads/cam at it. As already mentioned, power is a lot cheaper to come by with a smaller pulley and/or meth or E85.

 

If e85 is not available, you can always go the water/meth route, add boost, not timing.

 

Without seeing the tunes spark table it's hard to say how conservative it is. I know 5psi on 93 in a c5z with exhaust should make 500 so you're probably not to far off. Also, don't get hung up on Dyno numbers. The Dyno is just a tuning platform and all day is are different. Just enjoy it.

 

u should be above 500 eazy. Something is wrong. Even 91 Oct will still get u low 500's

Stock 2000 except 80inj and headers 10lbs boost 550

 

I'm curious about pulley and injector size

could be a very conservative tune and running fine but considering it started at 350 that blower should add approx 200 hp

 

I have the Stage II Intercooled System with P-1SC-1. I’m not sure the pulley size (still haven’t picked it up yet). I know the injectors were upgraded as well by PO but not sure the size. It is a 6 speed.

When making the appointment and selecting the headers the tuner said somewhere between 550-600 hp. So I was shocked when I got the email saying he was at 468. I’m waiting to see why the numbers were below expectations and what I need to do as I was hoping for close to 600 as that would be a beast.

 

Is it the twin intercooler setup? If so, I'm pretty sure those are known to not be so great...maybe the tune pulled timing for high IATs and he didn't notice?

From what I gather, the P1SC1 is smaller and/or less efficient than a V3si (just a quick Internet search because I don't know much about prochargers), but 468 still seems low regardless. The fact that the tuner says to expect 550-600 kind of concerns me honestly. Unless he didn't know which parts were on the car when he said that, I wouldn't expect anywhere around that with just headers. It should realistically be in the low-mid 500s tops depending on how aggressive he gets with the timing.

 

The tuner is a highly recommended shop. As to his knowledge, all he knew is it was an 03 C5 with a Procharger and SLP catback. He advised adding the American racing headers, new plugs, new wires (to account for the heat from headers). He was also going to install the fuel and boost gauges I ordered.

They are a busy shop (it took 10 weeks to get the appointment). I dropped it off almost 3 weeks ago. I knew they were busy and behind when I dropped it off, so I’m not trying to be that guy. I know the work will be top quality.

i want to discuss with him the tune and numbers, but was going to wait until he tells me the car is ready. I don’t want to rush them or be a PITA. He has emailed me updates (first to let me know that the intake bolts were lose, which he said may have contributed to the issues I described).

While there he did an inspection and replaced the gaskets (as he said they were flattened), and also replaced the oil pressure sensor (as he said it’s a common failure and since he was already there it would only be the cost of the sensor).

The next issue was with the fuel and boost gauges as he said he needed a different fitting and also mentioned that the A-pillar mount I gave him was not a good fit and would not look good after I stall. He requested to purchase a different one he normally uses ($90). He even mentioned waiting on paint to color match the new mount (I appreciate the attention to detail).

Apparently while waiting on the mount and paint he got it on the dyno and that’s when he emails the the update and told me just waiting to finish the gauges. That is why I didn’t reply questioning the dyno. I don’t want them to think I’m questioning his work. I’m just trying to understand.


I’m sure he will give me all the info when I pick it up but it’s not done yet. I feel like a kid at Christmas. I know what I’m getting I just can’t have it yet. Plus you guys are giving me a lot of hood information and questions.

Thanks again and keep the input and potential questions coming.

 

My c5z has the twin intercooler system and a P1SC-1. I just finished the tune on it. Straight 93 and just exhaust and my car made 620rwhp. My it's were 15* above ambient temps. They are wonderful kits. I actually was told by A&A not to change my blower out for their ti-trim as I wouldn't gain anything. 🤷‍♂️

 

Only that? Sounds a bit low.

What was the ignition advance on that pull?