online170

More of a suspesnsion/chassis question, than an engine question i suppose.

Im pretty happy with the amount of power my car makes at the moment. It will be dynoed this summer to put some real numbers to it, but i should hope its atleast 350 peak around 5000rpm.

It makes for a very very very effortless driver, which is the car's primary purpose, and a pretty good track car for weekend fun.

However, i was curious to know how much of a power loss we are looking at from the flywheel to the rear wheels? And obviously, what are ways to minimize it.

I would also imagine, the more power you make, the more is robbed by some of the robbers, so id like to start a list of stuff i could do to minimize that.

Some of the items on the list include;

1) Electric waterpump
2) Underdrive pullies
3) Solid motor mounts
4) Solid tranny mounts.
4) Adjustable shocks in the rear for drag racing

Any idea how much id save by doing that?

Sonix

iTrader: (1)

None of those parts would lower your RWHP vs your BHP. The first two may increase your BHP (and therefore your RWHP) and the last one would just help you hook up your HP. #3,#4 would do very little other then making the car feel more solid.

Increasing your RWHP vs your BHP (that's what you're going for here right?)
could be done by-

synthetic tranny fluid
synthetic rear end fluid (red line, amsoil,etc)
Checking your u-joints for bind/tight spots. Replace if necessary.
lighter weight driveshaft, AL or carbon fiber. This is debatable though
light weight flywheel - again, debatable
minimizing gear drag in the rear end, less preload on bearings? - not a fantastic idea....

etc.

Blue1989RS

Its been known that certain rear axles take more torque to turn than others. You might be able to take a dial indicator torque wrench and see how much it takes to turn yours. Then play with pads and gear oil to lower it. Automatics take way more power away from the wheels than a decent manual.

Instead of electric water pumps, you may try to install an underdrive pulley. But all these things mearly lower the power needed by accessories run by the engine. To increase efficiency you'd have to change heads and pistons. Increasing your compression ratio also increases your thermal efficiency.

online170

First off, arent BHP (Brake horse power) and RWHP (Rear wheel horse power) the same thing? WHich is why i said BHP/RWHP rather than BHP vs. RWHP.

Secondly, what im trying to accomplish, is transfering MOST of the power from the flywheel to the rear wheels.

Assuming my engine produces 350hp/torque at the flywheel. I would assume, a big chunk is lost by the time its transmitted past the tranny, driveshaft, rear end, accessories, etc....

So at the wheels, it might be 320?ish.

So im not trying to increase the efficiency of power PRODUCTION, but instead power TRANSMITTANCE. I would imagine, its a logical assumption, to look past the flywheel to do that. Right?

I see now, how the drag shocks wouldnt matter. Again, im looking to minimize power loss from the flywheel to the rear wheels, not necessarily traction or internal engine stuff.

Im curious about the rear end preload stuff? I guess its what makes the rear end "tight". Why is it a bad idea to minimize drag?

Also, i didnt realize, but its probably important to mention, im running a 1995 T56, with 80 000 miles, and fill synthetic tranny fluid. I dont think it was abused, because it was in a car that had been a daily driver, and was hit in a crash.

It has poly trans mount (with 3 bolt). Stock driveshaft, with old U-joints. probably have alot of play in that.

And stock rear end for now, but hopefully a fully built one with 4.10 gears in a couple months, from a TGO member.

DJP87Z28

If you have 350 HP at the flywheel you will lose about 16%. This flywheel HP is lost due to the complete drivetrain (tranny, drive shaft, rear axle and tires. So your 350HP is now 294 RWHP to the ground. So nothing you suggested is going to help very much. This number is for a manual tranny.

Sonix

iTrader: (1)

Yes, I understood your meaning online.

BHP is measured using an engine brake (ie, it doesn't have anything to do with your cars brakes or anything). BHP = FWHP (flywheel HP).
BHP, subtract 15-20% and you're at RWHP.

So yea, 290HP or so.

A rear end that is tight, will have less slop so it will tend to be stronger, but may draw more HP. Rear disc brakes tend to drag, vs drums, so that will draw a smidge of HP.
A GM 7.5" 10 bolt is a pretty low HP draw rear end, since it's so light duty. You're winning on that one.
Put in synthetic (red line if you like) oil in it.

Check your U-joints. Mine were very stiff when new, that draws HP. I think they will wear in though. Yours are probably fine now.

online170

Cool. Ok so obviously, 100% of the power wont make it to the wheels, its just the way it is. But what is a good ball park?

I think the member im buying the rear end from, is including royal purple fluid, and i will check on the U-joints.

So 20% for auto, and 16% for manual eh? Thats kinda crappy.

Sonix

iTrader: (1)

Yep, that's the ballpark. No free lunch
I'm shooting for 300RWHP. Here's hoping right?

online170

Yea hopefully thats what i have too. Dyno shall tell all.

WHen i bought the car, it felt like it had 200hp because of factory intake/exhaust and a crappy old 80's cc version q-jet. The seller claimed it had 434 when running its best with headers, and a 2x4 660 cfm, tunnel ram setup. I didnt beleive him, but after i helped it breathe with headers, an intake and carb combo, i think he might have been right.

We shall see in a couple months.