Guest zfan Posted April 16, 2002 Share Posted April 16, 2002 Anyone out there run dual plain and then switch to single plain? I went from a rpm airgap to a victor jr. and was surprised at how much low end I lost for what feels like minimal upper end power gains. Im running a sbc 350 30 over. 10.34 to 1 compression. Comp cams extreme energy xr288hr. cam is a 236/242..520/540 with 110 lobe sep. Cam is a roller cam with 1.52 roller rockers. Heads are edelbrock rpm's. carb is 750 double pumper. Headers are Hooker super comp long tubes. 2 1/2" exhaust with flowmaster two chambers. Pete jackson gear drive. Tranny is a vette 700r4 with 3.54 r200 rear with 235/60x15 tires. Im seriuosly looking at swapping back to air gap dual plane. I really miss the low end push. Saturday night had wife in the car so I didnt race but was tempted as 2 LS1 Trans Ams and Z28 wanted to play but stoplight racing to 60 70 miles an hour I seriously doubt car could hang anyway! Anyway just wondering what experiences anyone else had with switching combo's. Mike Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted April 16, 2002 Share Posted April 16, 2002 Hello Mike, Typically a single plane manifold works better for top end performance and not so well on the street with respect to torque. Dual plane manifolds seem to do better as thier power range is usually from approx. 1500 to 6000 RPM depending on MFG and model. I would say that for what you gained in the top end, you probably sacrificed some of the fun from the reduced torque. If you had a trans brake you probably would not notice as much when you come out of the hole because you are at max torque. I don't know what RPM you are turning, but if it is lower than 6000-6500, I would consider putting the other manifold back on. I hope this will help. Ken Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted April 16, 2002 Share Posted April 16, 2002 This is true, The Victor Jr. is a great manifold when your RPM band is within 3,500 to 7,000 Rpm. So basically you would need a stall convertor, trans brake to really benefit the launch. Try a line loc and a good 3000 rpm stall and your Victor will wake up, better yet, get some fresh slicks and feel the power!! With that 700R4 1st gear, add the stall and the slicks, you will be popping a 1 inch wheelie easy. Quote Link to comment Share on other sites More sharing options...
grumpyvette Posted April 16, 2002 Share Posted April 16, 2002 the victor jr style intakes produce all their power in the 4000rpm plus range where the performer rpm style produce most of their power in the 1000rpm-5000rpm area, if the cam your useing has over about 235 degs@.050 on the intake and your gearing keeps you above 4000rpm most of the time durring a race the victor intake will normally give you better et/mph in the 1/4 mile, if your cam has less durration or your average rpm is below 4000rpm theres no question the performer rpm intake will work better. that loss of low rpm torque can be gotten back while keeping most of the high end performance to some extent if you accept at slight loss in extreme high rpm power (above6500rpm) by adding a plenum divider to that victor intake,(down the center of the plenum front to back) just get some aluminum sheetmetal fold it in 1/2 (forming a tall narrow letter (V) upside down) and place it under the carb in the plenum it should be as tall as the plenum and about 1/2" wide at the base and 1/8" wide or less at the under carb area,(make a pattern before cutting the aluminum with paper its much easier to get correct that way)try to fit the ends as closely as possable but don,t get crazy over a perfect fit either, it should wedge firmly in place to test it,once you find the height that works best epoxy the divider in place in the plenum. btw sometimes a slightly shorter height like 2/3s as tall as the plenum works even better you will need to play with it to find out, hope that helps Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted April 16, 2002 Share Posted April 16, 2002 "Can be gotten back"? whaaa? Hehe, just keep the Performer airgap and when you get a stall and other stuff to make the Victor work, slap on the Victor, but whatever you do, do not get rid of it!! you will regret it later. Quote Link to comment Share on other sites More sharing options...
pparaska Posted April 16, 2002 Share Posted April 16, 2002 Even though many knowledgeable people told me the Vic Jr would work in my application (240Z, 3.70 LSD, 26" tire, Tremec 5spd, 12-677-4 Comp Cams cam, 9.7:1 compression 327) I choose to keep put my Holley hi-rise dual plane (PN 300-36) on to start with. I figured the cam was at the top of the streetable range as far as IVC, overlap, etc. and I wanted to maximize low end torque to begin with and find out where the dual plane started laying down. I have a Vic Jr. too, but I'll probably wait until I do some drag testing, get a road dyno or G-tech, etc. and baseline the car before experimenting with the Vic Jr. Heck, if I go to EFI, it'll all be moot anyway. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted April 16, 2002 Share Posted April 16, 2002 Nah Pete, thats what the Victor Jr is for heh, convert it to EFI, it'd work a treat for that! Even the holley could lose its fuel bowls with some billet block off's add a TPS on the thottle and some fuel rails and injector bosses, aftermarket computer and voila.... Regards, Lone Quote Link to comment Share on other sites More sharing options...
pparaska Posted April 16, 2002 Share Posted April 16, 2002 Daggon, we stole this thread didn't we Lone Yeah, the Vic Jr may become a base for a Holley Commander 950 TBI setup, or get bungs put in it for port EFI.... But I love the look (and hp potential for a later, large engine) of that Holley Stealth Ram,... Quote Link to comment Share on other sites More sharing options...
grumpyvette Posted April 17, 2002 Share Posted April 17, 2002 btw Ive done intake swaps at the track to find out and in most cases the victor type intake will out run the rpm type intake in street racing type engines, but like I said above your gearing and cam must match, Im betting you did not rejet that carb and tune that engine correctly for that intake if theres a loss of power in the 4000rpm and up range under drag racing type rpm levels with the victor intake ,yes theres no doubt at all that the rpm intake has more torque in the idle to 3500rpm range but your not in your engines effective power band in that rpm range while racing, only while driveing around town, and driveing around town takes very little hp! btw read this http://www.chevytalk.org/forums/Forum64/HTML/008625.html Quote Link to comment Share on other sites More sharing options...
Guest zfan Posted April 18, 2002 Share Posted April 18, 2002 Hey Guys, Im running a B&M holeshot converter. 2500 stall I believe. My problem is like I said while on the road cruising around at 2000-2500 and a ls1 pulls up The car really is a slug and he gets on it and hes gone. From a stop light the car flies like a bit-- and would be a heck of a race but from a low rpm cruise its just not all there. I know I could drop a gear/down shift but that doesnt always work. I think Im going to look at plugs this weekend and see if Im a little rich. I maybe need to step down a jet size or two. Thanks for all the imput. Ive actually got performer and air gap rpm plus torker in the garage so I could go alot of ways but want to try to keep the Victor jr. The car is set up to come on at 2800/3000 and run to 6500 rpms. Cars a garden variety slug under 2500rpm's. Thanks Guys, as always I appreciate all the imput! Mike Quote Link to comment Share on other sites More sharing options...
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