One thing to think about with the IR runner setup.... if you don't put your port geometry into the equation and where you can put the butterfly in the runner you might not have enough flow thru the butterfly to feed the cylinder all it wants. The introduction of the throttle blade and shaft will hurt flow unless you gain CSA, then that WILL hurt the pressure waves which lowers cylinder filling. If you have enough length and enough port tapper it's possible, but a plenum that is basically unrestricted by throttle body seems to be a better answer.

Bret

 

Don't doubt 650 rwhp at all but I was sure imitated to see the 630 rwhp N/A from a stock block LS7. Stuff just keeps getting better n better.

Have an 08 C6 on my current shopping list within the next few months. Still wrestling with what to do but my current thought is a standard 376ci Z51 doing your basic heads, cam n headers. Later down the line doing a large ci block. Heard rumors from a very good source Chevy will step the regular C6’s up again sometime after the 08’s to be within 10% of the power output of the LS7 motor. Something like the LT4 vs the LT5 which killed the value of the LT5’s.

 

So if you are unrestricted as far as hood clearance (say in a mid-engined setup where the intake is coming over the roof anyway) is there more power to be made with the individual runner set up on a 468 LSX with worked over LS7 heads (or C5R heads if they are any better), or should I use my extra space for a massive plenum with one large throttle body up top?

I was working with that engine simulator you suggested and I couldn't get the IR intake to make power to save my life.

Jeremy

 

Yeah I saw that LG picked up a '08 already and they are already doing 480rwhp! Hey it happened with the last ZO6 with the C6 so why wouldn't they do that to the newest version! The blown deal is probably going to be a killer motor out of the box with way too much power on tap once they start playing with the motor. I guess we will see when they try working over the heads on that setup.

Not massive, sizing the plenum is the key here. If it's too big the motor doesn't recover from shifts, if it's too small then it's not going to feed the motor well enough.

Bret

 

I'm tempted to listen to Keith Duckworth and just accept the fact that I can't build engines. Oh well, I have plenty of time to get all the details worked out, I can save plenum sizing for another day.

Thanks,

Jeremy

 

Bret

Have a friend whom is a former LGM employee and did a kiss n tell with me regarding some things the shop does. If you will read the rest of the string on the 480 rwhp, other people for some odd reason cannot reproduce the same results. Maybe it's because they didn't remove the belt, placed the car on the dyno in a special way, had no mufflers or removed the rear brakes.

Lou and I have butted heads in the past and he has mellowed some since then. Actually enjoy talking to him as he's pretty witty and charming in person. He hasn't quite mellowed all the way. Still pretty "aggressively" sells headers n cams.

The LGM cam only C6 that was displayed with mine at the 2007 Dallas Autorama (same one that’s on the Speed Channel) had no muffles and sounded pretty wicked to say the least. Can’t imagine any normal individual whom would consider a straight through exhaust as a daily driver. Sure my wife would love to pull up to valet parking for dinner in a no muffler car. She just digs that stuff and we would be the talk of the restaurant.

In reading some of the former posts I see one recommending a twin turbo LS7 setup. A lot of the big Ford guys are running turbos and I've seen several SBC trying the same thing. When the turbo cars are tuned on the money, nothing can touch them. I know of one mustang in the king of the hill class that dynoed over 2800 hp three years ago. Problem is getting them on the money is next to impossible. He either smokes the tires, gets all kinds of sideway or kicks butt. About once a year he kicks butt.

Turbo cars are now allowed in Pro Mod and Troy Coughlin has been trying to sort out his turbo car. So far he hasn’t and not a single one has placed in the ADRL top 8 yet this year. Still hard to beat a large ci big block with a ton of nitrous in sportsman racing.

 

I have been looking at LS7 parts. It seems my goals are achievable with a 427ci LSX based high compression motor. Run it NA for brackets and add nitrous for the "quick" events. I don't think I would need to spend a fortune on heads - the LS7 pieces might even do the trick out of the box. Use the LSX block, LS7 heads, and a stout rotating assy. and it looks to me like a $12,000 long block. Remember - all I need is ~1,000hp. The motor ought to be good for 700-800hp easy with 360cfm head flow. A 200-250 nitrous shot on top and I would be good to go.

Rich

 

Rich,

I have that motor basically being built right now.... except we are closer to that hp number NA. I wanna say it's closer to $20K for the full motor @ 440cubes, but that's with a sleeved block and the extra cubes thru bore not stroke.

The LS7 heads with the prep they need to run with valves in them and a decent spring kit is roughly $4500. Going with a race prepped set knocks that one into the $6000-$7000 range. Even stock heads will move 370cfm on the intake and 230cfm on the exhaust.

Bret

 

Wow Brett.....that is impressive. What is the final bore on it? I would be interested in doing something along those lines. At that power level I would throw my other build idea out the window. Those heads are the real deal

 

Out of curiosity what separates the “ $6000-$7000 Race Prepped” heads from the “prep they need to run with valves in them and a decent spring kit is roughly $4500” heads? Also how much more flow ( I know your going to say “valve train weight and stability) do they represent over the: “stock heads will move 370cfm on the intake and 230cfm on the exhaust??”

As in our prior e-mail conversation Lou replaces the valves, spring and re-ports the exhaust on his ZO7 cars that I have seen 630 rwhp out of.

 

You make a good point, Denny. Handling the potential flow is very important as is the quality of that flow. Getting all the details right counts a lot...and costs a lot! But I'm preaching to the choir here.

 

Denny for what I can say on here.....

It's a full CNC porting of the intake, exhaust, chambers.... new valve guides, custom intake and exhaust valves (not like the $4500 don't have custom intakes), "double throw down" valve job, prep for JBE shaft rockers etc...

Lots of little things... last time I checked flow was up to 382cfm/280cfm. Don't think there is not a lot going on there with the intake, most of that is just fixing the stock production problems and making the intake port geometry right for the cubes and RPM range, it's very similar to the stock port shape/size. It also moves 376cfm with the intake manifold bolted up! There is much more work on the exhaust, MUCH MORE. The exhaust valves alone are worth a ton of flow on that side and in the area of 20hp.

There is a good amount more work done over the street heads like Lou runs. Then again there is a higher price tag and a bunch more tweaks due to the arena it has to run in.

Bret

 

It's a 4.175", but that power level and bore takes a Race Engine Development prepped LS block at something stupid like $6K a shot. The customer keeps yelling at me for an invoice, and I keep just giving him a $$$ countdown because the total is hard to come up with. I would say $20K total might do it, but it's doubtful. If we had to spin this thing more RPM, then you would have to go another $10K over that easy.

To pull this all off the old man is designing and building rocker arms that will beat down a set of top of the line Jesel's in unreal fashion, it has a sheetmetal intake and lots of detail work. At least when we are done the second time around it will be a LOT easier.

Once the rockers are done, maybe he will post up some pics and he can give a write up of them for the Advanced Tech crowd. They are really a cool deal, and are very impressive. This motor couldn't do some of the things I need it to do in the valvetrain without these things, the requirement of moment of inertia and stiffness that I need is about on par with Nextel Cup and Pro Stock so I needed something better than what we can buy.

Maybe after the motor has run it's race (and hopefully does well) we can give a better break down of what we are playing with here. Right now it's just a lot of work!

Bret