LS7 vs LS3-480 or 525

[Mike]

Here's my chassis dyno sheet. My goal wasn't to see how much HP the dyno operator could convince me I had, but to check AFR, spark/timing, fuel tables etc. and cleanup the GM crate motor spec'd tune/ECM.

Motor is the Crate LS376 (480HP), LS7 exhaust manifolds, straight air intake tube, no cats, to Hushpower mufflers, 5th (0.92) gear pulls on the G96.50 trans-axle, 93 octane fuel.
Max. wheel HP: 431.47
Max. wheel TQ: 421.07

 

[Jack]

That makes for a very lively street combination Mike. Good choice.

 

[marc]

I think that power up at the upper end of the spectrum is better to keep those transaxles alive. lots of low down torque will do the most damage. besides if your just puttering around on the street you don't need the power there. Remember these are light cars.

 

[Luke Lonberger]

What kind of dyno was this on?

Not trying to balk at your numbers but here is a 2010 Camaro I tuned that had only intake, headers, exh.

I really feel that the stock manifolds are holding you back. Would you guys be interested in true long tube headers for the SLC's?

 

[John Ross]

Big cubic inch, torque cam, Lower RPM = long lasting and power IMO. I am seeing 20mpg with my 690hp LS 441 very street friendly.

My thoughts exactly. I have a similar spec motor dyno'ed and installed in my SLC, although the car will not be finished and drivable until year-end or a bit later.

Are you getting 20MPG with your motor IN AN SLC? If so, can I assume you are using a Ricardo transaxle? Nothing else lets the engine loaf at 70 MPH on the highway without a custom R&P...

JR

 

[Warren kreyer]

My thoughts exactly. I have a similar spec motor dyno'ed and installed in my SLC, although the car will not be finished and drivable until year-end or a bit later.

Are you getting 20MPG with your motor IN AN SLC? If so, can I assume you are using a Ricardo transaxle? Nothing else lets the engine loaf at 70 MPH on the highway without a custom R&P...

JR

Yes SLC and ricardo, It will run about 1200 rpm at 60mph in 6th. I usually with run in 5th gear, much smoother. I can probaly play with the engine tune to get it smoother but the engine wasn't set up to chug like that.

 

[Stu Coleman]

Hi Luke

I'm confused by post #44.
You suggest that stock manifolds are holding the power back (no doubt they are compared to long tube equal length headers). I assume you posted the Camaro figure, with long tube headers, as a comparison to show what it achieved with headers? yet, 419hp is lower than Mike's 431hp with stock LS7 headers (I also run LS7 manifolds).
Can you please clarify?
Are you expecting the SL-C power figure to be higher than Mike's 431hp because it has less drive train loss?

cheers
Stu

 

[Mike]

What kind of dyno was this on?

Not trying to balk at your numbers but here is a 2010 Camaro I tuned that had only intake, headers, exh.

I really feel that the stock manifolds are holding you back. Would you guys be interested in true long tube headers for the SLC's?

My car has the gm LS3 (480hp) motor. Isn't the factory 2010 SS Camaro spec'd at 426HP figures? My Dynojet chassis WHP number is in the range of my expectation - power train loss 10% or so using a transaxle. As noted in my post the goal of my dyno time was for tuning purposes only - specifically AFR/spark cleanup. I also told my tuner that this car could see a 20-30 minute road course session and to keep in mind that I was not looking to extract big 1/4 mile hp or times to sacrifice engine longevity.

I'm with Stu, I don't quite understand the reference. Luke, are you saying your expectation is that the WHP should be more.

Long tube headers would be nice, but the LS7 manifolds are built well, tight to the block, hydro-formed and cost me all of $195.00 for brand new take-offs.

Regards - Mike

 

[Shane]

Having driven GTM's with pretty much every engine mentioned so far in this thread (including the LSX iron block), I guess I'll throw in my $.02.

First off, the LS7....you might as well plan on $19k at least. By the time you buy all of the stuff you need to install it and get it running, that's what you'll have in it. Dry sump adapters, oil tank, AN hose and fittings, ECU and harness, bracket and accessories, etc.

I've never been all that impressed with them. You can safely plant your foot to the floor at pretty much anything less than 4k rpm. There just isn't much low-end torque there to work with. Even in 2nd gear in a GTM, you won't spin the tires if you floor it at 3k rpm. Good news for the transaxle, but not much for seat of the pants WOW factor.

The LS376 525hp is very similar experience to the LS7....keep in mind it's a year or two between driving the LS7 and this engine, but I came away feeling that you could probably swap the two engines back and forth and have a very difficult time telling the difference. Less than half the price of the LS7.

LS376 is the most drivable of the bunch. Still, at "normal" driving rpms, I doubt you'd see much seat of the pants difference from the above engines. At the upper rpms, the other 2 would probably noticeably pull ahead once they get into their upper rpm "sweet spots"......but for less than half the cost of an LS7.....actually almost a third of the cost....you just aren't going to tell that much difference IMO.

The LSX iron block (Mast Motorsports, FAST intake, 700++hp). Violent, brutal acceleration. Flooring it at 60 mph in 6th gear at under 2k rpm is no problem. Shifting down to 5th at 60mph at 3k rpm is brutal acceleration. Flooring it at 60mph in 4th?.....I wouldn't even think about it. And that is with 345 Pilot Sport Cup tires on the rear.

 

[John Ross]

Having driven GTM's with pretty much every engine mentioned so far in this thread (including the LSX iron block), I guess I'll throw in my $.02.

SNIP

The LSX iron block (Mast Motorsports, FAST intake, 700++hp). Violent, brutal acceleration. Flooring it at 60 mph in 6th gear at under 2k rpm is no problem. Shifting down to 5th at 60mph at 3k rpm is brutal acceleration. Flooring it at 60mph in 4th?.....I wouldn't even think about it. And that is with 345 Pilot Sport Cup tires on the rear.

Rubbing my hands together and salivating slightly...

JR

 

[Luke Lonberger]

Howdy guys. I posted that dyno because with your gear ratio being .92 the dyno is actually reading 8% higher than what the engine is really making.

Also because I was confused by your hp levels since your engine has a Gmp cam and the car we tuned made about the same power with only headers being the difference.

The LS7 manifolds aren't bad for the money, but we have seen over a 47 hp and 45 TQ gain at the wheels by simply installing a set of long tubes with an x pipe and tune.

Cheers.
Luke

 

[Fran Hall RCR]

Luke,
there is no packaging space for true long tube headers and a cross over in the SLC...we have tried ....the extra heat build up and lack of space would also create knock on effects for heat management too

 

[Stu Coleman]

Thanks for the clarification Luke. So, Camaro engine starts off with less HP compared to our 480hp yet is achieving similar power to Mike's with only the addition of headers. This makes sense then because your 47hp increase is achieved via long tubes headers and in our engine GM achieved the 50hp increase by way of a Cam.
As Fran says we can't go the long tube header route to achieve power gains.

 

[Alex]

Thanks for the clarification Luke. So, Camaro engine starts off with less HP compared to our 480hp yet is achieving similar power to Mike's with only the addition of headers. This makes sense then because your 47hp increase is achieved via long tubes headers and in our engine GM achieved the 50hp increase by way of a Cam.
As Fran says we can't go the long tube header route to achieve power gains.

You can do equal length long tubes, I just don't think you can fit a h/x/180* crossover back there

nom nom nom nom nom nom nom

 

[Michael]

You can do equal length long tubes, I just don't think you can fit a h/x/180* crossover back there

nom nom nom nom nom nom nom

Wow... Can that be polished? That would very cool all shined up in the engine bay.

Mike

 

[TSR]

Starting out with the "KISS"method with a stock LS3, In due time I most lightly will get an itch to upgrade the engine. I think this is a good thread to see the collective brain power of this forum to come up with ideal upgrades for a LS3 to be used as street car and an occasionally a track day.

 

[Dave Nugent]

Why not just go with a turn key LS7 like this?
https://www.texas-speed.com/p-4386-tsp-441-cid-680-hp-ls7-turn-key-package.aspx

 

[TSR]

I haven't found the tree that money grows on yet, until then I'm open to ideas about the best bang for the buck for a stock LS3. I did order the chassis modded for a supercharger for future upgrades.

 

[mahlon]

Fran is right I just finished tig welding and installing my exhaust yesteday. We are running the ls376/525 we used the ls7 manifolds. I installed the stock cats 12 '' race mufflers and ended with 4'' stainless tips out the back. The system can be installed or removed very easily. Nothing fancy to get past street registration, We will look into the side exhaust possible later. I am not sure how much I could improve the exhaust given the space..

 

[Chris]

Are you able to post a couple of pics of this exhaust setup? Trying to determine difficulty, packaging, heat transfer, appearance, etc.

Fran is right I just finished tig welding and installing my exhaust yesteday. We are running the ls376/525 we used the ls7 manifolds. I installed the stock cats 12 '' race mufflers and ended with 4'' stainless tips out the back. The system can be installed or removed very easily. Nothing fancy to get past street registration, We will look into the side exhaust possible later. I am not sure how much I could improve the exhaust given the space..