Hi, I'm wondering if it will be worth to get a tbss intake for my lm7. In Canada it seems much more expensive to find one of these intakes than in the US. So power numbers vs dollars spent it may or may not be worth it. My lm7 has a sloppy stage 2 cam specs, with a th350 and 2500 12" stall. Stock truck intake. The engine has flat top pistons and was bored .30 over. The heads are 862. The power it made was 330hp and 388ft lbs on its most recent dyno run. Not sure how accurate the torque number is because the tuner said it won't be 100% accurate due to "slippage" on the dyno. I know the tbss and a larger tb will flow a lot more air but whether its worth the estimated $600+ is the real question. People have reported 10-15hp gains but would my setup benefit at all or would it just be a flop? The gearing in the rear end is 3.08 and recently bought 3.73s. The car is a 79 Camaro and it feels way too sluggish off the line for that torque and HP number to be accurate. The gears will probably make a massive difference and will be putting them in soon. New gears means the car will have to be retuned and thought maybe the intake could benefit the upgrade at the same time. 2 birds one stone. I'd love to hear anyone's thoughts and insight

 

Depends on the RPMs that those HP & torque numbers occurred at. Just the numbers themselves only tell part of the story.

At any given RPM, HP = torque × RPM ÷ (33,000 ÷ 2pi), aka HP = torque × RPM ÷ 5252.11. Note that to get high HP, you have to have both high RPM, AND high torque AT THAT HIGH RPM. Torque at lower RPMs isn't a factor in "high HP".

That cam isn't known for good low RPM torque. Virtually ANY cam that increases horsepower does so by moving the engine's optimum operating RPM upwards, including that one. In doing this, lower RPM torque is usually sacrificed, by moving the whole curve upwards in RPM. Any increase in HP occurs at the engine's highest RPMs, which ... isn't where it's operating, coming off the line. All of which is why putting a "big" cam in a "small" motor, and then forcing it to run at low RPMs coming off the line like 2500 as you have done, makes it slower from a stop, even than a stoick cam would be. Without fail. IMO that's not a good cam choice for the rest of the combo for that reason. Your car would probably go MUCH faster, or at least FEEL that way, even though a dyno will show "less HP", with something more like a "Stage 2 truck" cam; the typical 212°/218° kind of thing you see available everywhere.

Gears will make a MASSIVE difference. Won't change the basic mismatch though.

Any effect from changing the intake will not be noticeable except at the very highest RPMs the engine ever runs at. Unless this is a dedicated strip car, which it doesn't sound like, it's not gonna make the slightest difference in typical street type driving. Personally I wouldn't waste money on it, in that case. I'd put in a more appropriate cam for the purpose you use it for instead.

 

Hey! Thanks for the response and info.

So I'll attach the dyno sheet so you can see where the numbers all happened at. The shop that tuned this car I don't think did everything they could for the driveability side. It does have some idling issues and it throws the CEL on for an "idle too high" code if I adjust the idle screw on the throttle body. Otherwise it just tries to stall when coming to a stop. One of the other side effects of that cam is such low vacuum. Once I get those rear gears in I want to see how the car feels and responds. I am expecting a huge difference but will it be everything I wanted the car to be in the first place? Who knows. I won't be changing the cam due to the amount of money and time I've already put into this build, I have to live with that unfortunately. This was my first time around doing anything like this and should have done some more research in the initial stage but gotta live to learn.

 

The tune is obviously a problem, but it's relatively easy to solve. A lot of tubers can do remote tuning and get you in shape over the phone/email and download it yourself. The 2500 stall s crap, you need a better/higher stall for that cam. TBSS intake is a plus, I'm going to have 3 of them for sale next week, will give you a heads up. The Sloppy cam was a mistake, but you can make it way more better with a few other mods.

 

Yeah changing the intake won't help with that. Probably won't hurt, butt won't help either. I doubt you'd be able to tell any difference at all except by the effect of weight reduction centered at the driver's wallet. Your mainmost problem is the grocery-cart gears, pure and simple.

Definitely get it tuned better. That'll help. Changing gears won't require changing that later, necessarily, especially if you let your tuner know that you'll be doing that.

Other than gears, a smaller converter with a higher stall will help considerably with "leave", like 11" and 3200 RPM. Trying to make a large converter stall at a higher speed produces a mushy, drawn-out stall, rather than a crisp on/off type behavior. You end up with too little hookup for a few hundred RPM above the nominal stall speed, aka "slip", which does nothing butt waste power and heat up the fluid. Problem is, in a street car, you should ideally arrange so that the engine RPM is comfortably above the stall RPM at all times during steady-state driving with the converter fully "locked up", otherwise it "slips" constantly just driving down the road, and all the lost energy thrown away by the "slip", goes into the fluid and heats it up. With 3.73 gears and an actual 27" tire, meaning 13.5" when you pull a tape measure from the center of the wheel to the ground, NOT "calculated" off of the "trade size" numbers like 235/60-15 or whatever, this puts drive shaft and therefore engine RPM (ideally, assuming no slip) at about 2800 at 60 mph, or 2100 at 45; meaning, any realistically chosen stall speed, is gonna try to burn up your fluid, just like it always has for people with non-OD transmissions for as long as I've been in this hobby (near half a century now). You're gonna need a BBBBBIIIIIIIGGGGGGGG cooler to keep your transmission alive even with what you've got now.