dbs1vette

Swapped my LS3 based 416 from an 02 camaro to my current 04 Z. Dyno shows I've lost about 25hp20/tq. Corner exit not as fast and doesn't pull as hard down straights or on my buds viper despite using the same exact tire and being 300lbs less weight than the camaro.

Camaro stock trans vs Z trans

Camaro 3.73 gears vs Z 3.42 gears

Camaro 1 7/8 headers, no cats, straight through exhaust with bullet muffs vs Z 1 7/8" headers, high flow cats, elec cutouts and OEM TI exhaust

Camaro cable 92mm tb vs Z 90mm LS2 tb fly by wire tb (just ported)

Camaro open front with ram air SS hood to high flow filter vs Z bottom feeder air with huge Halltech cai

Ideas on where the power above 5000 rpm has gone?

z06801

It might have hooked up with my oil pressure and now they're on a crime spree, let me know if you see them sorry for no help

dbs1vette

I agree, you are sorry...hahaha.

I think I'd rather have a few horses run off and join the circus then my oil pressure. I had that happening when I first ran this engine and made the mistake of using off the shelve Mobil 1. After a few laps it was down around 25-30lbs. Switched to Mobil 1 RACING 0-50 and have not had that resurface since.

6SPEEDZ

You have a lot of variables for the same engine. I remember Camaro's stock vs C5's stock (non Z06) would put out more power on the chassis dyno. Cats vs no cats is definitely part of it. Headers are going to be a few horsepower different at least as is the intake. As far as corner exit speed that could be setup, a limited slip that has gone bad, driving style or the Camaro is a better car. Camaro's generally like being manhandled more where a Corvette likes to be finessed. Also are you on the same dyno? Are the conditions near the same as when the Camaro was dyno'ed?

dbs1vette

Same dyno. Similar conditions, but they were able to correct conditions. Headers on camaro were TSP, headers on Vette are ARH. I agree that no cats on the camaro could be some of the power issue.

Camaro was certainly not a better car, not even close. Vette has been corner balanced and handles corners much better and the rear end has no issues. It's all in the power difference.

Timing a video of both on same track, same basic weather conditions and tires and the vette is slightly quicker through everything but the straights. Actually significantly quicker through the chicanes, but slower overall all on a 1.25 course by a little less than a second, fastest lap to fastest lap.

6SPEEDZ

Well you said corner exit speed which is mainly handling not power. Now you are talking about straightaway speed which is power related and drag related. The solid axle Camaro has less parasitic loss than the Corvette. It probably has less aerodynamic drag than a C5Z also.

6SPEEDZ

Correction I just looked up the aero numbers and the C5Z is still better even with the notchback window.

dbs1vette

Yeah, you beat me to that. Exit speed may also be gear related? With the 3.73 gears in the camaro vs 3.42 in the vette, though the trans gearing may offset that??

I'm thinking it's all mostly part of air in, exhaust out and that the camaro rear uses less hp then that of the Z.

And I guess one more thing as far as track times...I drove the camaro with much more abandon then I do the vette, simply because one was a beater, the other a little nicer. Of course on the last road course all that was forgotten when I had to duke it out with some uppity ZL1's.

JerryTX

How old are your valve springs?

dbs1vette

1.5 years and 6000 miles. Oops, that's since in the Vette. Total is 3 years and probably 8500 miles?

JerryTX

If the lobes are very aggressive and have a lot of lift, and the engine was tracked a good amount (sustained 4-6krpm), it is not unexpected that the springs have fatigued in that time, and you are down on power. Your exhaust and gearing could make up for the differences you are describing, but your springs could too. Consider a fresh set of springs.

hklvette

Do you have dyno plots you can post for each? Is the torque curve for each the same up until about 5k rpm? If it is, I would put on a straight exhaust instead of the Z06 mufflers and re-test.

dbs1vette

Not sure if I can lay my hands on the dyno graphs anymore, but above 5500 is where it's most noticeable. As mentioned previously, just un bolting the factory TI axle back gained 15 hp, but due to its use on the street I won't be using a straight through exhaust. I installed some elec cutouts that bumped it up 7hp.

My shop has also suggested a complete head freshening and sending the cnc ls3 heads to wcch for additional port work as well as springs. There is over $2000 for that and about the same just to drop the engine to pull the heads. OUCH!

JerryTX

Same clutch in both cars? Going from LS7 to a 16lb race clutch netted me 11rwhp. I agree on the exhaust: full 3" all the way back = great power at this level.

If your heads are ported LS3 GM castings, assuming they aren't botched up to start with, then you are unlikely to gain more than 10rwhp going to a better LS3 GM head. For a high winding 416, a move to TFS's LS3 255cc head would be more interesting. But now we are just pissing away your money: what is the target? Are you just trying to regain the HP? A valve spring swap should be ~ $500, start there. What are your cam specs?

mgarfias

If you had the intake off while doing the swap, look for vac leaks.

dbs1vette

No vac leaks and although the clutch is a little lighter than an LS7 it's good and not getting changed at this time.

I think it's time for valve springs in the next few months and that should help.

JerryTX

Didn't mean to suggest you should change your clutch, only that IF you went from a lightweight clutch in the Camaro to a heavier clutch in the Corvette, it could account for some power loss.

Doing valvesprings is always smart: I lost an LS2 when a weak spring allowed valve contact at the rev limiter. It is just good insurance.

dbs1vette

Gotcha. I would have liked to have used a lightweight clutch/ flywheel, but the camaro burned at the track and replacing it was an Unforseen expense, so I used the clutch I had in the camaro which is a single mantic.

When it's time to replace I will do something different. I think the spring update is a great suggestion!