Carbureted LSX forum - Victor Jr. or Performer RPM?

Putting a carb'd LS1 into my father's Panoz for road race duty. Due the class power/weight rules the car can only make 330-340 rwhp max. In planning the project I was set on a Performer RPM manifold as the rpm range shows 1500-6500 and the car will have a 6200 rpm rev limit and be capped power wise.

However, the Victor Jr. just looks so much cleaner. But is it too much manifold for a 6200 rpm motor? Would it kill mid-range vs. the Performer RPM?

Thanks,

Brian

go whit the rpm. it makes more mid-range than the victor j. and for that power level it will be just right

Common debate here. You won't lose much midrange with the single plane. Remember being an LS motor it is going to make more mid range than a first gen SBC did anyway. IMO going with a single plane is no different than going one cam size smaller. IDK how people separate the choice of intake and cam like they do.

Being a race car the question you need to ask yourself is what transmission and rear gears will you be running and what RPM's you will be shifting at. You need to tune your motor for that RPM band.

If I were you I would build the motor to be a rev monster. A carb'd, stock cam LS2 has a HP curve that is still climbing at 6200 RPM. Build a car to run up there, then plug in a lower rev limit for the tech inspection. Then, on race day, if the rev limit just happens to disappear you will be at a competitive advantage.

If the car will be operating above 4000 most of the time, use the Vic jr.

IMO going with a single plane is no different than going one cam size smaller. IDK how people separate the choice of intake and cam like they do.
Smaller? Wouldn't a single plane be like moving to a bigger cam i.e. more high end powerband? As for separating intake/cam choice, I'm buying a stock LS1 crate motor that will already make more power than allowed by class. Thus, I have no intentions of changing the cam and have no need to turn high rpms. Excess rpm just increases wear and temps.

Being a race car the question you need to ask yourself is what transmission and rear gears will you be running and what RPM's you will be shifting at. You need to tune your motor for that RPM band.
TKO600 with a Ford 9" with 3.50 gears. Car will have a 6500 limit but be shifted around 6200. This is why I initially looked at the Performer RPM.

If I were you I would build the motor to be a rev monster. A carb'd, stock cam LS2 has a HP curve that is still climbing at 6200 RPM. Build a car to run up there, then plug in a lower rev limit for the tech inspection. Then, on race day, if the rev limit just happens to disappear you will be at a competitive advantage.
This is what we call cheating and we're not looking to cheat to win plastic trophies and lose the respect of all of our fellow competitors. If the car magically runs away from everyone it's pretty easy to know somethings up and then you'll be sent straight to the dyno at the track. Yes there are very creative ways to switch tunes, boost profiles, rpm ranges etc. but I'd rather win from my driving then from knowing I found a way to add 50 horse I wasn't supposed to have :nod:

If the car will be operating above 4000 most of the time, use the Vic jr.
It will be... 4000-6200 will be the most common rpm area, but a few turns on the tracks we frequent will have dips to 3000. Plus during a race if you hit traffic etc. etc. there are times when you need the mid-range.

Read a few comparison tests and it seems that the Victor takes over at 4800 rpms, but the Performer is stronger below that. Probably going to stick with the Performer for this application.

I can see you're not a big fan of Smokey Yunick.

Yes, worded that wrong. Picking a dual plane over a single is like picking a cam one sized smaller.

What I am trying to say is to tune the engine for the RPM band you expect to run. 4200-6000 is not exactly street cruiser RPM so no excessive wear and temps there but whatever.

So somehow you need to reduce the power output of the stock LS1 to make the plastic trophies real. so whenever you figure out how you are going to do that pick your cam and intake accordingly. Or you could do like everyone else seems to want to do and pick the intake because you want "mid range", then use a whole different set of criteria to pick the cam cause somehow that is not subject to the same rules of physics.

The difference in oil temps shifting at 6500 rpms vs. 7000 rpms on a hot day at the track is about 20-25 degrees. 260s vs. high 280s and that's the difference between "OK" and needing to back out some (I back out when I hit 290 oil temp).

I'm going to leave the stock LS1 cam in it and slap a performer RPM on it with the existing Pro-Systems carb we have. Going to use stock LS6 manifolds mated to the existing side exhaust and see what it makes. I'll restrict it if I have to.

if it makes to muhts power stock. pull the timing a bit and you can decrese the power that whay. you can if you goot a dyne tune the timing. so the motor makes the same power in say 5000-6200. rpm

Based on your description of your race conditions, I think the performer RPM is a great choice. More torque off of the corners and out of traffic. It will also require less jet and squirter to tune and might even consume less fuel.

if it makes to muhts power stock. pull the timing a bit and you can decrese the power that whay. you can if you goot a dyne tune the timing. so the motor makes the same power in say 5000-6200. rpm

exactly what I'd do in your situation, dyno test, then pull timing at the RPM where the motor starts to make too much. Set the timing curve up to maintain that max power as far out in the rpm range as possible.

I would choose the RPM manifold for your app.
As far as exhaust manifolds, I'm sure they will meet your needs, but a half ass set of headers will make more torque all the way through the rev range, and could give you a BIG midrange advantage,( even though you will tune the peak downwith pulled timing) and you WONT be cheating,making 330-340 RWHP over the widest possible rpm range
my .02
Barrett

I can see you're not a big fan of Smokey Yunick.

careful about pinning a cheater label on the man in the white overalls. he found the "gray areas" in the rule books, he even said himself that putting a bigger engine in a racecar to win was cheating, and any idiot could do that. he would do things that weren't in the rule books at the time....like using larger diameter fuel line to up the capacity. if its not in the books, it's not cheating.

back on topic. the performer will make a great intake for what you are trying to accomplish. one of the magazines (or maybe it was a youtube group) did a test on the LS327 and found that in an otherwise stock engine with a carb, there was no reason to use the victor jr. it lost large amounts of torque in the middle and only gained a few hp(read less than 10...i think even less than 5hp) up top.

As far as exhaust manifolds, I'm sure they will meet your needs, but a half ass set of headers will make more torque all the way through the rev range, and could give you a BIG midrange advantage...
Come over and weld up some custom long-tubes for me ;)

http://sphotos-b.xx.fbcdn.net/hphotos-prn1/545065_3842031380521_1113254809_n.jpg
http://sphotos-a.xx.fbcdn.net/hphotos-ash4/403492_3842031660528_1390448752_n.jpg
http://sphotos-b.xx.fbcdn.net/hphotos-ash4/482998_3870582174273_1459855379_n.jpg

As you can see regular headers won't work as the car is side exit exhaust. The Panoz GTS cars that came with 5.8 carb'd crate motors (351 windsor Ferds) had Headman headers, but Headman doesn't make them anymore. They said they would if the Panoz owners could do a group buy, but then I'd have to cut the Ferd flanges off and put LS flanges off. All and all too much work/$$$ for marginal gains vs. just adapting the existing pipes to LS6 manifolds. Also, I'm getting rid of the big ass flowmasters and installing some Magnaflow race mufflers.

careful about pinning a cheater label on the man in the white overalls. he found the "gray areas" in the rule books, he even said himself that putting a bigger engine in a racecar to win was cheating, and any idiot could do that. he would do things that weren't in the rule books at the time....like using larger diameter fuel line to up the capacity. if its not in the books, it's not cheating.

back on topic. the performer will make a great intake for what you are trying to accomplish. one of the magazines (or maybe it was a youtube group) did a test on the LS327 and found that in an otherwise stock engine with a carb, there was no reason to use the victor jr. it lost large amounts of torque in the middle and only gained a few hp(read less than 10...i think even less than 5hp) up top.
Exactly! If the rules don't say you can't do it then it's legal until they update the rules :)

that looks like crazy fun.nice car man!

That does look like TOO much fun!
you can get cheap shorty headers for an LS that would not be too hard to adapt. If you do that, make sure you get at least 1 3/4" primary tubes, or else you may as well stay with the manifolds.
I think your doing the right thing getting rid of the fartmaster muffler and going magnaflow. Its hard to tell what size exhaust tubing you have, but My opinion is 2.5" might be on the small side, but certainly quieter than 3". I like 3" even in your application.
lol, I think it would be reasonably easy to make a set of mid length headers in that chassis!, but that is just me lol
Good luck, and have fun with that cool machine!

Performer will help low mod torque to pull out of those curves while giving top end at your rev limit, granted the jr will give a couple extra hp up top but with that rev limit/ road race I would go performed all day

if its not in the books, it's not cheating.

Exactly the joke I was trying to make.

http://www.popularmechanics.com/cars/news/vintage-speed/top-nascar-engineering-cheats

Also, not to be a pest, but I believe the article you reference on the performer vs. vic jr was using a 5.3 with stock cam and valve springs. The motor completely ran out of breath past 5K RPM or so. If it is the article I am thinking of they even said they knew it was experiencing valve float. It didn't take much to guess that a single plane would have been a poor match for that motor. Sometimes it isn't so much what one single part will do as much as what it prevents. Fix the valve float and give it some better flowing heads and the better breathing manifold becomes more obvious.

The OP is in sort of an odd spot in that the car can't exceed some peak HP. So might as well build as fat of a power curve as possible. That means less shifting. But building power at an PRM that you never use is just a waste of time. Sort of why it was important to figure out the shift points before he started building a motor.

The OP is in sort of an odd spot in that the car can't exceed some peak HP. So might as well build as fat of a power curve as possible. That means less shifting. But building power at an PRM that you never use is just a waste of time. Sort of why it was important to figure out the shift points before he started building a motor.
Ding ding ding... winner winner chicken dinner. The correct way to make a class killer would be to build a detuned big cube motor that makes torque everywhere, but peaks at a specific horsepower. But that engine would be double my budget for this entire restoration project.

Ding ding ding... winner winner chicken dinner. The correct way to make a class killer would be to build a detuned big cube motor that makes torque everywhere, but peaks at a specific horsepower. But that engine would be double my budget for this entire restoration project.

I am glad I finally stated it in a way that was understood.

I have issues with that at times.

I have issues with that at times.
Communication via text is never ideal. Always something lost in translation.