Car clutch questions (trying to make something from nothing)

[GoceKU]

I know this may not be the right place to ask questions like this but as past has proven there is surely a lot of knowledge here. I'm planning (plotting) a plug in engine swap for a vehicle that has lots of limiting factors, the biggest one clutch and flywheel options the gearbox is a manuel and needs to stay stock and it has only a 200mm clutch disc. The question is how much power and torque can u push thru a standard 200mm street disc clutch, the engine i have in mind develops 167hp and 235 nm of torque can i make it work, any experience or advice is much appreciated.

 

[pontiac428]

If you need to retain the stock gearbox, then the choice to run the stock clutch is made for you. If you can get a performance clutch for the vehicle the transmission came out of, that will help. In my experience with Honda, which runs small clutches, is that they can take about 250 whp before the factory (good) clutch starts to slip. I know that 400 whp will burn the clutch quickly and that 200 whp clutches last forever. Any of these power levels are not a problem with a performance clutch.

 

[Superburban]

There is so many variables, I doubt there is a answer based on diameter. Friction material, pressure plate springs, weights, operating RPM's, I think will all be factors. Look at racing clutches, it seems wrong that they have less surface area then standard clutches.

 

[pontiac428]

I was trying to avoid the variables and the endless discussion and just go with what I know from engine swaps and hands-on power adding by putting big turbos on small motors. Typically, the platform will decide your drivetrain for you. As in, if you want to build a given car, you must use a given transmission. The long story made short is that stock small car clutches generally are a lot tougher than they seem, and so are small transmissions. The OP showed a small V6 making 167hp and 235 nm of torque- that's only 175 lb-ft, not much to write home about.

 

[eugene13]

I was trying to avoid the variables and the endless discussion and just go with what I know from engine swaps and hands-on power adding by putting big turbos on small motors. Typically, the platform will decide your drivetrain for you. As in, if you want to build a given car, you must use a given transmission. The long story made short is that stock small car clutches generally are a lot tougher than they seem, and so are small transmissions. The OP showed a small V6 making 167hp and 235 nm of torque- that's only 175 lb-ft, not much to write home about.

I agree

 

[stioc]

I'd like to know how much hp/torque the original engine made which the clutch/flywheel/transmission came from. If it's in the same ballpark as the new engine I wouldn't worry about it at all.

 

[GoceKU]

I'm plotting to swap the little niva's engine 1,6l 75hp engine with this 3l v6 PRV engine, one thing i forgot to mention aftermarket, racing clutches are not an option for me, importation taxes and customs charges are ridiculously high, like 3x more than the purchase price. I can buy standard clutches for any other car. The gearbox on the little niva is the same as old fiat and alfa romeo, they are known to hold 200-250 hp.

 

[stioc]

I'm plotting to swap the little niva's engine 1,6l 75hp engine with this 3l v6 PRV engine, one thing i forgot to mention aftermarket, racing clutches are not an option for me, importation taxes and customs charges are ridiculously high, like 3x more than the purchase price. I can buy standard clutches for any other car. The gearbox on the little niva is the same as old fiat and alfa romeo, they are known to hold 200-250 hp.

A 75hp clutch on a 167hp engine (it's the torque that matters more) could be a problem. Since the gearbox of the Niva is used on the fiat and alpha romeo with more hp (and presumably more torque too) the gear box is good to go. Any chance you can retrofit the flywheel from the Fiat/Alpha to the Niva or get a used/junkyard gear box to go with the engine?

 

[DAT510]

Torque is the number to look at. Motorcycles and engines like Honda's S2000 put out HP (in the 200+) range at High RPM's , yet have low peak torque and fairly small clutches. HP= (Torque x RPM)/5250

Regarding 200mm clutches.. VW Bugs and many Datsun L-series (Nissan) motors used 200mm clutches (L16, L18 and L20b). I've seen Bug Motors putting out 180+ HP w/ peak HP @ 6000 RPM that puts the torque ~ 157 ft/lbs @6000 rpm, and higher at Peak Torque. My Datsun L20b put out 140 HP at the wheels with a peak wheel torque of 158 ft/lbs, I'm estimating 180+ft/lbs at the flywheel. I used a 200mm clutch, with an upgraded (Datsun 2000 Roadster Pressure Plate) 1750kg clamping force and it lasted 80,000 miles of spirited driving and auto-xing. Of note both Bug's and my 510 hover around the 2000 Lbs range. Heavier vehicles will be harder on the clutch regardless of torque.

If you can get a heavy duty pressure plate, it would help too.

 

[pontiac428]

The VAZ motor from the Lada makes 86 lb-ft.

When doing an engine swap, you need to use the flywheel that fits the engine crankshaft and the clutch disk that fits the input splines from the transmission. You can machine and adapt flywheels, but you are stuck with the transmission input shaft. If you are lucky, it is common and you can find many clutch disks to choose from. So you'll probably be using the flywheel and pressure plate from the V6, if it fits under the bellhousing. Otherwise, you'll be re-drilling the flywheel from the Lada. If the clutch is weak, you can shim the diaphragm and pressure plate for more holding force at the cost of pedal effort.

If the V6 has a much higher redline and power peak than the L4, then you can relieve stress from the clutch by reducing the gear ratio in the final drive. If you are at, say, 3.73 and you change to 4.11 in the rear end, you reduce the stress on the transmission by at minimum 10% for the same load (assuming 5th gear 1:1, difference is much more for lower trans ratios).