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Lonnie's is a no go on the tb . Vendor who made them has moved on, site looked a little dated but you never no if you don't ask. Back to wilson or accufab, btw: whipple has a 109mm tb also.
Just had our 415 LS3 on the engine dyno recently. At 660hp a swap from a Holley 750 to a Holley 850 carb showed zero gain, maybe 1-2hp.
A 2" plenum spacer under the carb showed over 20hp and 12ft lb of torque through the entire powerband.
I think there's a major hard-on right now for throttle body size because of these 468 dyno results. There are major assumptions that the throttle body is the limiting factory because the datalog showed a big vacuum. I think the main restriction is in the manifold itself. I'd consider a 108 vs a 102 an incremental change and not transformative.
A larger plenum intake with the appropriate runner volume and length...now that's got potential to be a huge gain.
I woulda thought it woulda been atleast at or over 700 crank with a carb style intake. What's the combo on that ? My buddy that builds some ls dirt car motors gets about 740 out of pretty simple hydraulic cammed 4xx ls stuff using gmpp ls3 heads on his budget builds.
The victor jr is too small for it. Out of breath upstairs. Going to a bigger carb didn't do anything. If I trip over a pile of money I'll put a hi-ram on it and see what it can do.
It was also a very honest dyno at Westech. The dyno was just for break-in and to find best spark, which was 29*. Didn't do anything to try and push more power. The carb didn't have a carb base or velocity stack on it which definitely hurts power. Also, we didn't lean it out to find best power. We run them fat for racing as they're more consistent that way. It was 11.5:1 for all the pulls.
In our 3100 pound '80 malibu wagon it went 10.04@131.90 at a non-sea level track with a gentle timing curve off the line to keep it from flipping over backward. With full timing it was going over without a lift. 1200' altitude and 2500 ft DA, no wind. It rips. Lots more available from the engine I do agree. The car isn't chassis certed so I can't make any runs faster than 9.99 or 135 mph. We'll creep up on that 135mph limit and do other things to keep it out of the 9's. When we do make a 9 second hail Mary I want it at least in the 9.80's. Just making it carry power to 7500 it would pick up another mph or two.
The SBE L92 let go at 750 runs. We think one of the flycut piston exploded. This engine should literally last forever which is all I need in this car.
4.065 x 4"
FED stage 1 LS3
11.4:1 on 91 octane
243/257 110+2 hydraulic
Victor jr port matched to the heads w/ Holley 750
Mahle forged pistons, 1/1/2mm rings (these are a lot higher tension than you'd think...)
Vacuum pump
Manley 4" crank and 6.125 rods.
The cam could use both more overlap and more duration. The power carried very well, but torque peak was ridiculously low at like 5000 rpm. Really surprised for a 243 intake lobe and the size of the FED port.
Hio, the Cam is to small for 700 as a hyd. roller with small stuff missing, vac pump, etc.. 700 think Speedtrigger with the small stuff and LLSR. Spanks the Super Vic would help or intakes with more plenum area. Have the same basic set up as you just a Super Vic 4500 and solid roller and the small stuff.
Also Spanks with a 110+2 lsa where would tq peak with a 114+2 lsa? Carries tq past 5k? That port program doesn't need much to rev or go. The 4 inch crank is what ATE the 243 cam duration and gave you the 5k numbers.
700 apparently isnt as easily as I thought. I only made 657/575 pump gas and 671/574 chp vp race fuel. On a engine dyno this past weekend. However the sniper intake carried tq and hp over a huge curve
Think Speedtrig would have few a pointers after tests with that induction system. My baseline for 700hp is: 250+ duration @ .050 with a solid, from 402+ ci or 4 inch crank min 11.5 comp. If you know what a 4 inch arm likes in terms of duration @ .050 which equates to rpm with a given compression you''ll have the world opened up to you. IF THE INDUCTION ISN'T HINDERED. I've flipped flopped. But choose a intake like a tunnel ram & pro filer: single 4500 top. Straigtest Line of sight and easy to port. Going for a look as well. If a holley hi ram base can get 8800+ with a FED $400 cnc program (TSP Ls3 record camaro and Ls7 heads) i pick how it looks. Think those 6+ inch long runners need shortening for the look desired. So a Welding school instructor was met. 5.6 is about a standard port center line length for Ls7 heads and 10.5 to 10.6 is wanted for total runner length including intake. Cheap Chris U billet intake. The aluminum version. Out think the problem?
So long as the intake port and cam would benefit from more RPM then any engine should pick up power with shorter runners.
With short runners at slow engine speeds you get crap cylinder fill because there just isn't enough draw from the cylinder. You use up the readily available air in the runner, and that's about all you get. Short runners need as much air in as short of time as possible, but you need to get that air moving from the plenum.
Long runners make power based around inertia fill. At slower engine speeds the valve stays open longer as a function of time, so that long slow moving column of air keeps filling the cylinder even when the piston starts going back up.
The good long runner intakes are free flowing enough with enough plenum volume to still support some higher rpm engine speeds, ie FAST102 and MSD, ls3 and ls7.
The long runners start to choke at high rpm because it takes too long to get all that column of air to start to move at high speed. By the time the big gulp of air reaches the intake valve it has already closed. A late IVC can be a bandaid to try and make a long runner intake still make power at higher speeds. These huge cam stock intake engine builds would be better off with an earlier IVC and a more appropriate intake design for the rpm range.
I think the lack of good intake manifolds led to the internet theory that LS3 heads don't like overlap, and that you can't beat a stock LS3 intake. It wasn't true, there just weren't off the shelf parts around to make a good high rpm LS3 until recently.
1) Thing is when either runner short or long can't supply the demand (with enough plenum area ? your intake choice ) that is observed without the intake on. Key problem! 2) shortening the runner just raises where peak tq accurs. i like the look myself. CID runners are about 5+ inches in length vs the holley at 6.31 in. long and some longer with intakes like the MSD or FAST. refer back to steps 1 & 2 for anwsers.
For efi to make carb hp, the fuel needs more resident time in the plenum and runner = fuel being introduced higher up in the intake track. Spoke with Mike Thermos, said my thought process is on a PS level as far as my approach.
NOS Dry Nitrous Plate for Holley LS Hi-Ram EFI Intake Manifolds-Black
I think there's a major hard-on right now for throttle body size because of these 468 dyno results. There are major assumptions that the throttle body is the limiting factory because the datalog showed a big vacuum. I think the main restriction is in the manifold itself. I'd consider a 108 vs a 102 an incremental change and not transformative.
I don’t think that’s an unreasonable assumption. In a flow path, the restriction will cause a drop in pressure downstream, not upstream. If the MAP sensor is reading vacuum in the plenum, it would be because the throttle area is causing it, not because of the runners.
Injectors are right on the port exit because for low rpm it offers the best performance, efficiency and emissions quality.
The higher the RPM the further upstream you want to inject the fuel, until the point where it is actually better to have the injector outside the intake tract entirely.
F1 fuel injectors are at the entrance of the trumpet.
03-27-2019, 03:45 PM
The aluminum version. Out think the problem? 
