How would these two engines compare in a small sports car like the latest ND Miata at around 2600lbs?

According to GM the numbers are slightly up for the 376/525 both in power and torque, agreeably not by very much:

LS376/525
525 HP @6200 RPM
486 LB-FT @5200 RPM

LS7
505 HP @6300 RPM
470 LB-FT @6300 RPM (probably a typo, I guess it should be 5300?)

But how would they compare in real life character, driving dynamics, throttle response etc. etc?

Anybody that has experience of them both side by side in the same or similar vehicles?

Obviously if you added a nice cam to the LS7 like the ASA in the LS376/525 it would be a whole other story.

Thanks,

 

Are you considering building a Miata with one of those engines?

If so, there are a number of Miata's which have been built with the 525 HP engine.

Don't have any information on a direct comparison between the two power plants.

If you haven't you should check out the YouTube build series by Turbo Tom where he does a Miata conversion with the 525 HP engine. He does a build and then gets it chassis dyno tested and does some passes at the drag strip.

Flyin Miata did a swap of the 525 HP engine into a new ND Miata but is not selling parts yet to allow others to do a conversion so you are stuck with an NA or NB or NC for the time being.

 

I'm sure you know that the LS7 being an OEM engine, it will be much smoother than the LS376/525 (ASA-cammed LS3). The ASA cam lopes like a dog crapping peach seeds.

 

Yes, the plan is to build on an ND. I have indeed seen the Youtube series of that NC build you mention and I have been talking to Flyin' Miata a couple of times now.

Thing is that I have an LS7 in my current kit car and I just love that engine. However FM says that it's a very tight fit to the steering rack and that their custom oil pans will not work with the LS7 since the rod bolts would apparently hit it. Not sure if the stock dry sump pan will clear either, FM says it probably wont, and it's also no room for the oil tank in the engine bay. So either put it in the trunk or convert to wet sump. I guess everything is possible, it's just a matter of how much time and money you'd like to spend.

My plan was to get an LS3 and swap it in my current car and sell it. And then use the LS7 for the Miata. My finances however wont allow me to get the Miata and try to fit the LS7. I need to sell the current car and also fully functional to get some decent money for it to be able to buy the Miata. So a bit of a catch 22 there.

I know FM does not sell the ND conversion parts yet but hopefully that will change during this year I've heard from them.

I've heard and seen some video clips of the LS376/525 and it sure idles and lopes pretty rough but it still seems to drive pretty nice. I have a much bigger cam in my LS7 at the moment but that one is coming out regardless.

All in all there is no question that I'd prefer to keep the LS7 but the main question is how much work it would be and what oil pan to use. The other alternative would be to sell the current car as is and just get an LS3 for this build. But I would probably have to start with the regular 430hp to have any decent chance to get it through the registration process here in Sweden.

Has anyone heard of oil pans so low that the rod bolts would hit it and that it could work for an LS3 but not the LS7?

Thanks,

 

Compromise - 376/480. Most numbers I've seen it turns out right at 500HP and won't be as ill mannered as the 525 might be.

Do I remember from another thread - you're selling this once you re-power it? If I'm remembering right - I'd just put a stock LS3 in it. 430, 480, 500 in a 2600 lb. car - it's just not a big difference day in and out on the street. And to me - stock drivability is much more important than a few extra HP.

 

EVOVII SWE- Just keep in mind the ENTIRE difference between the stock LS3, 376/480, and the 376/525 is the cam. That is ALL!

 

I have an AC Cobra kit car with an LS7 today. I'm selling that car but I would like to keep the LS7 for my new ND Miata project. However Flyin' Miata says that their custom Moroso oil pan will not fit the LS7 since it's too shallow in the front and the LS7 rod bolts would actually hit the oil pan.

I need to sell the current car in working order to get a fair price for it and the initial idea was to buy an LS3 and put in it while keeping the LS7. But that was before this oil pan issue arouse.

A stock LS7 drives like beauty and I think it will be perfect in the Miata. Selling the current car with the LS7 and buy a new LS3 for the Miata just doesn't feel as appealing to me, the LS7 is kinda special and I really like it

I got a couple of pics from FM that shows the installation.

 

Yes, I know, I think the valve springs are upgraded on the 525 as well but that's it I think.

 

Valve springs?

 

The 525 has the same lift as the 430(a LOW .525"), so the valve springs are the same. A cam with a LOT more lift (at least .600) would do the LS3 a LOT of good. With the correct springs, of course.
What many do not know is that both the Hot Cam and ASA Cam are very old designs from the small/big block era, with the attendant low lifts. But they serve a purpose without GM having to engineer new cams.

 

Managing peak lift isn’t the only variable —- the lobe profile, especially ramp rate, also a big factor. I just assumed with more aggressive valve events the springs would also be upgraded - but have no idea for that application.

 

I THINK GM uses the same springs for all three engines. The LS3 has more lift on the intake (around .550) than the others have anywhere. So the LS3 springs will work for all three.

 

From a Grassroots Motorsports forum post.....


"More of an FYI than anything else, I learned something this weekend.

I'm turning an LS376/480 crate motor into a LS376/525. Basically, a 480 is a stock LS3 with a GM "Hot Cam" in it and stock valve springs. A 525 is a stock LS3 with a GM ASA cam and "higher rate valve springs" Yes, that's nearly 100 hp from a cam and spring swap. Gotta love big domestic V8s. FYI, the Hot Cam and the ASA cam have the same 0.525" lift.

Anyhow, I called up GM Performance Parts and got the number for the new valve springs: 12586484. That's a yellow LS6 spring. But it's been replaced with part number 12625033. No worries, you can even buy a cam and spring kit with those springs.

I went to install the 12625033 springs, and they looked exactly like the ones I was pulling out. Not just similar, but identical. I checked further, and whaddya know - 12625033 is the part number for a stock blue LS3 spring. And looking at the spring rates, the older yellow springs had the exact same rates, just with a 0.570" max lift instead of the 0.550" for the LS3.

Just for fun, I peeked under the valve covers of a 525 crate engine. Blue springs. GM, you're busted. You're not changing those springs at all. The 525 just has a cam swap. Which is pretty darn impressive, but still. Makes me wonder why that particular crate is so expensive."

 

BIG surprise! lol Like I said.... LS3's with cam swaps. The more HP, the more you pay for the same-priced hardware. "GM economics"

 

I know I read somewhere that the springs where upgraded but maybe it was somebody that assumed it must be that way, like I kinda did, a very dangerous thing to do really. Good thing it's never too late to learn though, thank you guys

Also the pricing for the GMPP controller kit is higher for the 525, more expensive zeros and ones I guess as the HW is apparently 100 % the same

Anyway, I have decided to keep my LS7, put back the stock cam and tune, convert to wet sump and use it in my new project. Somehow I'll sort out the oil pan clearance issues.

So now I'll start looking for the best possible deal on an LS3 crate, I was thinking about buying it as a set with a T56 and GMPP controller kit so I'll get the rest of the parts for my new build as well

 

Good deal! This way if desired you can put a cam in of your choice, as there are far better cams out there than either the Hot Cam or the ASA cam.

 

I have also been looking at that 525hp engine. For quite a while. I noticed about a year ago the price of that engine went up by about $1000 from all of the mail order places online. Like has already been mentioned, the controller got more expensive as well.

You guys are confirming what I pretty much found out. The 525hp engine is just a really, really expensive cam vs one of the lesser rated hp LS376 engines.

I'm all about value and I don't think that there is much value in the 525hp engine vs the lesser LS376 engines.

 

I've decided to go for the 376/480 if I don't find anything good used. Keeping the LS7 for my new project

 

If I'm not mistaken....the 430 hp. Crate and the 525 both have .525 lift cams.........how the f*** can that be.....look it up....i **** u not...

stock ls3 430
204/211. .551/.525 117 LSA

525HP.
226/236. .525/.525. 110 LSA

DOES THE DURATION AND LSA REALLY ADD THAT MUCH.....DIFFERENCES SEEM SO MINIMAL

WHERE THE HECK IS 95HP COMING FROM??

 

Yes, yes it does.... MUCH more duration AND a closer LSA add a lot of power. ALL with .525 lift that only require the same springs as a stock LS3.