The ones with the electric exhuast cut outs that allow you to "uncork" the headers like your running open exhuast. One of the guys in my club has them on an old Bel Air and they are awsome. I want them for my vette. Anyone else use them? Comments please!

 

I use em on my 98 vette. Email me with any specific Q's that you have and I'll let you know all you want about em.
:cheers:

 

Hey, who makes those? I've been looking for a set with an electric valve, but can't find them on the web. Read an article many months ago about them and forgot to write down the company name. I too would like to know how reliable they are. Heard they tend to leak. Are they on the headers or anywhere you want to put them on the pipes? :confused:

 

Not sure about electric, but I know Jeg's has the ones that you unbolt. My only concern with these is that if your carb's a/f ratio is set with the exhaust on, then you uncork it, it may run lean. I'm sure someone has them and some more info about them :cheers:

 

Cappy has the ones you unbolt on his car. Sounds great with them off. I am planning on putting them on my exhaust when I get a 3" new one put on.

 

There was a link recently about a company that made them.
I lost the link, but have a small video of the prouct here.

 

http://www.quicktimeperformance.com/qtec_main.htm

Was lookin at em awhile ago, made sure to keep the link. Still plan on doing it eventually, should be a pretty sweet system for that "on demand" volume that you just need when sitting next to a ricer.

 

that link is even better then the info i got. Doug headers in Anaheim made a set for a club member's 62 Bel Air and their awesome( cost is $450 per set). Anyway, i am unsure of the size of my exhuast (true duals) but i think it is still stock.Dont see why the cost is so different for them being they are th same thing. I am inclined to go with dougs because of the fact that i know someone who uses his. Why dont you more mechanically inclined types peruse the two sites and give everyone your .02!

 

Wouldn't that hurt your power with it closed and not give you the full gain with it open? I would think you would want it to be straight through and not have a spot that the exhaust would get stuck in and restrict the flow and when the valve is open you don't get all the exhuast routed out the open half, but would that cause an increase in power since a lot of it would be going out the open part, but some would flow out the rest of the system? Hmm. Probably best still to just have that full system blocked off and the other one opened.

 

that might be true, thats why i hope someone much much smarter then me takes a good look at this as far as power is concerned. I assume that its all about being able to "uncork" your V-8 rumble sound. More of a smoke and mirrors "show" mod rather then a true horsepower increaser. Still,very cool and still under my consideration.

 

These are the plates that I use http://www.mccordcg.com/mpp/faq.htm They bolt onto a standard flowtech cutout that you weld in before your exhaust. About the exhaust getting caught in the end of the dump when closed, that doesnt happen. The pressure created by the exhaust creats a "bubble" in the pocket and the gasses just flow right over it. About not all of the exhaust escaping when the cutouts are open, thats not the point of the cutouts. The reason for using them is to realease pressure. It doesn't matter if 100% of the gasses escape, you are just reducing back pressure A LOT.

As for a power increase when uncapped, or opened, you can feel the difference SOTP. And the sound is awesome when opened with no cats. My Heads/cam/header 98 vette sounds like a stock car when running both cutouts open.

FWIW The electric cutout plates are my favorite upgrade that I have done to my 98 vette. Being able to open them next to a mustang cobra and let my cam rumble is awesome. Then after I break his eardrums I can close them in a matter of seconds with a toggle switch to avoid unwanted attention from the police.

 

Thanks man, they have em cheaper on that website and they look like even better quality. Needless to say, I got a new bookmark in my favorites now. :thumbs:

 

Both the Quik Time & the McCord are popular with the 4th-Gen Camaro/Firebird guys. There's another manufacturer that uses a sliding gate instead of butterflies to open & shut the exhaust. I'll try to look it up if you want.

Right now, since you got true duals, exhaust is not the "cork" in your setup. A cam change should be number 1 priority. Then some distributor work to match your mods. You'll be swimming in 14s then, and be embarassing the imports at the track, LOL. Oh yeah, all that for about $200 and some time.

 

Thanks Nassy,

I found McCord's site to be very interesting. It's got me thinking...

Chuck

 

What type of cam would go best with the edelbrock performer?

 

The Comp Cams Xtreme Energy line seems to be really popular. Crane Cams are also popular.

When selecting a cam you need to first determine what your goals are and the other modifications, if any, that you are going to do. Matching the head, intake, and cam characteristics is the way to make the most power.

So, the bigger question is, how fast do you want to go?

 

power from idle-5500RPM is what the performer seems to be doing for me now seat of ther pants wise. i think i will stay with this area 0-5500 RPM. If this proves to expensive or difficult then maybe move up the rev range to the mid rangs but i think most peolpe associate the small block as a stump puller and that is a good place to start. A daily driver high torque low in the power band vette!!!!

 

You’ll not be able to see the full positive effects of a performance manifold until you upgrade the rest of the engine's breathing flowpath. It appears you have a relatively free flowing intake & exhaust, good start. The next critical point of flowpath restriction would be the intake & exhaust valves. The camshaft controls those valves. The higher the valves lift off their seat, the greater the flow thru the engine. The longer the duration that the valves stay open, the greater the flow. Physical limitations of cam grinds usually call for high (long) duration cam lobes for high lift profiles. Cam duration typically controls the rpm range where the power occurs (shorter duration=lower rpm, longer duration=higher rpm). Therefore, if you want low range power, you’ll be lift limited because the optimum duration will be relatively short.

There are cam grinds for RVs or tow trucks that could fit the bill, BUT I don’t think a Vette should run a cam like that. Those typically drop off in acceleration after 4000 rpm, similar to the stock L48 cam. What I do recommend for a high performance street engine is a cam that makes a strong mid-range, 2000-5000ish. That would keep you pressed back into your seat as you accelerate to the next shift point. Adjustments to your drivetrain may be necessary to optimize running an engine like this, but a mid-range engine can usually tolerate small mismatches without affecting driveability much. Typical adjustments include a higher stall torque converter and/or rear end gearing.

Some mid-range cams perform better with higher than stock smog-year compression. Some are designed to work with relatively low compression. If you are not going to upgrade your cylinder heads to obtain more compression, then shop for a cam like Comp Cams High Energy line, i.e. 260H. If you are contemplating more power, read on.......

Cylinder head combustion chamber size affects compression (smaller chamber=greater compression). Cylinder head’s intake and exhaust ports greatly affects the engines breathing (flowpath). And lastly, the combustion chamber design greatly affects the efficiency of the combustion-to-power process. These aspects of the cylinder head make it just as, or even more so critical than a camshaft, in engine performance. Some heads have great mid-lift, mediocre high-lift flow while others have mediocre mid-lift, great high-lift flow. Then others have poor mid-lift & high-lift flow (like stock smog-heads). And then there are those that are great all around. This flow characteristic is primarily what you want to match to the lift of your selected cam. Usually, a head that has great mid-lift flow makes for a good street head.

The cam alone should knock 0.5-0.7 seconds off your ET. The heads should drop another 0.5 sec. Headers at that point will get you another 0.2-0.3 sec. Distributor & carb tuning should be performed along the way to optimize the setup if you are going to do these mods in steps.

Whew, I haven't posted in awhile.......... sorry for the long-winded reply.

 

I took a look at the Edelbrock Performer cam specs (not Performer RPM) and the intake duration & lift look a little weak. The Comp Cams 260H looks like a good match to your setup. If you upgrade your heads, plan to upgrade from the 260H as well for even better performance. Anyway, it is always wise to call or email the cam manufacturer and get their recommendation for your particular setup.