Quickin

They dynoed it at the end for a hot test, ran it at high rpm's for 20 minutes straight. But they never said what the HP/TQ were.

Those heads look pretty nice.

My question about the LS7 is:

Besides changing the cam and porting the heads more, what other mods can you do to up the HP, without going into the engine and without adding forced induction or nitrous?

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Quickin

I don't see how this new LS7 is going to all of a sudden WHIP a fully built 427 C5R engine in the RWHP department with just a cam change and porting. People are talking about 650 RWHP, I don't see it happening. All the current tuners would go out of business because there are NO stroker engine packages anywhere for the price of an LS7 + porting and a new cam, that will come close to even 550 RWHP.

BurnOut

iTrader: (1)

I think that a lot of it depends on the intake. FWIW, I'd be willing to bet that with a kickass set of headers (1 7/8, merge collector, nice long primaries), a BIG cam, and tuning, 575-600 RWHP will be a possibility. I don't really think that there's that much left in the heads (especially since there doesn't seem to be room for a larger exhaust valve), so I think that there'll be a fair amount of experimentation there for a realtively small gain.

I just don't see 650 at the wheels on the motor without cranking the compression and running race fuel.

Quickin

I don't see it either. Some people will do the race gas thing, the giant car shaking cam, and whatever else they have to do to get it there, but than it'll be "oh I think its totally streetable?" Half the other people will say its not streetable.

I say 550-575 RWHP on pump gas is all the LS7 will do and still have A/C and be a daily driveable car that doesn't lope like crazy.

Big-DEN

BurnOut - why do the heads need a larger exhaust valve? Theres SB's making 800HP+ N/A with a 1.60 exhaust valve.

The current crop of LS1/LS6 "superstroker" in the 408-434CI range is making 500-565rwhp, with hydraulic cams
and head/intake when bolted together flowing UNDER 300CFM. Yes, some of the heads do 350CFM, but when the intake manifold is bolted on flow drops to under 300CFM even with the LSX...

This new manifold has a entry which matches heads exactly, and my guess it head/intake bolted together flow over 325CFM. Is just a guess we need someone to check it. If it flows 350CFM bolted together, watch out....

It is possible that there is enough meat in the heads to flow ported C5R numbers ( 400CFM peak and 300CFM by .400" of lift ). An exhaust port supporting 250-275CFM peak will support this and I'm sure that is there too.

And then someone will come out with a revised manifold for it. Prolly shorter runners a couple of inches shorter, fatter or with taper so that not much flow is lost when bolted to heads, which will support higher rpm operation and tq peaks.

The power is going to be there. Rememember we already have 565RWHP 408-434's with hydrualic cams
and the good boltons..

These heads are a bit better even stock, so as long as the intake mani supports flow bolted up to the head it is going to be a whole new level unfolded... Talking about the other side of 600rwhp and driving on the street, with TQ at every point exceeding what a factory 346 does - even off idle. Never said it wouldnt' "slobber" or pass emissions, but it will drive well at low speed due to massive displacement...

BurnOut

iTrader: (1)

DEN- I think that the issue with the LS7 heads is the E/I ratio... it can be "crutched" by using a cam with a loooong exhaust duration; look at the stock cam... it's what, 211/230 @ .050?? However, that only goes so far... add another 30-35 degrees on the intake side (read: like some of the bigger 5.7L/6.0L hydraulic cams) and you're looking at 260-265 @ .050 on the exhaust side. At some point it just makes sense to improve the exhaust flow, rather than go with a monster split like that.

marcus769

I have seen that also.. There was a show on Hot Rod Television. The dude's from Hot Rod Mag. went to the plant, and actually built and dynoed their engine.. It was very informative!

BurnOut

iTrader: (1)

You sure it wasn't a guy from Chevy High Performance?? I know an editor from CHP that went out and built an LS7, but I dunno if he had a TV crew with him... his name is Henry de los Santos.

Big-DEN

What if they didn't need all the exhaust duration? Sometimes it happens, even from the factory with an engineered cam.

I'm sure with porting this port can get to 250CFM which is enough to support 400CFM on the intake side.

Of course the formulas will say you need a 320CFM exhaust port but in actuality not necessarily true.

Quickin

Do you guys think a totally hogged out pair of AFR 225's will flow like the new LS7 heads totally hogged out?

zamboxl

iTrader: (1)

no it will not