650+ hp guys P2W clearance

[slowgsr]

Motor is ready to be machined, block is waiting for the machine work..

Weisco 9:1's
Manley Turbo Tuff Rods
acl bearings
arp main studs
kiggly gridle

Machining will be done with a torque plate installed as well.

Weisco recommends 0.0025 measured at bottom of skirt.. Im thinking I want to run these things looser, at 0.0035. Its not really a 'street' motor... It will see some street driving, but primarily track once the new setup is in.

What are you guys running who are making big power? I would really like to get some feedback on this. I know its very common to run upwards on 0.0040 on a honda, but I have no experience with DSM's.. yet...

Thanks!

 

[My1GLaser]

I definitely wouldn't run .0025 on your motor. It opens up to .003 after the coating wears off the skirt, but that's still too tight.

I won't comment on what to run, since I don't have anywhere near 650hp. Call Brian Nutter at Wiseco on Monday after you get all the opinions from here.

 

[slowgsr]

thanks, Im thinking of 0.0035 to 0.0040 but I will wait for more opinions, I also emailed Kiggly, see what they have to say.

 

[jwcardy]

See I am on the opposite side of things on my end. I trying to figure out what piston to wall clearance to run with my Wossner pistons. The spec sheet that comes with the pistons reccommends .007 but to me that sounds too loose from what i have read. This is still somewhat new to me.
-wes

 

[slowgsr]

It has to do also with what the piston is made from and how it will expand under heat.. but when an engine is cold its cold, and at 0.007 you would think there would be lots of slap untill it gets warm.

 

[Brianawd]

.0035 is going to be to tight. I would go .0040-.0045.

 

[jwcardy]

I'm stupid! I went back and looked at my spec sheet. Mine is not .007 it is 0.07mm which when converted to inches is 0.0028in which is tight. I wasn't thinking that my spec sheet would be in metric since my wossners are made in Germany.

 

[BoredDSM]

You do not provide us with the proper information to give you an accurate suggestion on piston to wall clearance. Pistons expands with different fuels under different amounts of pressure. You should be telling us how much you drive the car and what type of fuel and turbo you are using. When you call up wiseco they will ask you the same thing and give you a measurement based on there tests and estimates on the expansion rate of there pistons and rings.

 

[TSIfreek]

.0035 is going to be to tight. I would go .0040-.0045.

Im with brian.

 

[Black94DSM]

I'm shooting for around 550 hp and I am running .0045 piston to wall.

 

[Brianawd]

650hp on e85 is the same as 650hp on c16.

 

[slowgsr]

You do not provide us with the proper information to give you an accurate suggestion on piston to wall clearance. Pistons expands with different fuels under different amounts of pressure. You should be telling us how much you drive the car and what type of fuel and turbo you are using. When you call up wiseco they will ask you the same thing and give you a measurement based on there tests and estimates on the expansion rate of there pistons and rings.

100-200km street driven per month... 2-3+ track visits per month (seasonal only)
s366 ett
e85, q16 or c16.

thanks for the info guys, prob just run this thing nice and loose at 0.0040 i will call weisco tommorow

 

[4g64fiero]

I am running .0025 and plan on 500 whp with wisecos(still on break in right now). If the pistons are measured properly per wiseco's directions that come with the pistons, you shouldnt have an issue but then again, if you can run looser why not I guess. My car is street driven everyday and I dont plan on running 500whp more than oonce a month at most at the track. I have seen others run the same PTW clearance at 650whp, but there are plenty of people that have failures as well. I think some people just measure the pistons improperly or their machine shop measures it improperly. Best thing to do is to micromanage the build with your machine shop.

 

[My1GLaser]

I have seen others run the same PTW clearance at 650whp, but there are plenty of people that have failures as well. Best thing to do is to micromanage the build with your machine shop.

Agreed!

If I'm not mistaken, jeffgst on the Link forums cracked his cylinder wall from too tight p/w clearance on Wisecos. I can search later today, but I think I remember a few guys over there complaining of skirt issues with too tight p/w clearance. I have mine at .003 which is why I remember reading those threads and wishing I went a little looser on my build.

 

[awddsm95]

Your Piston to Wall clearence really depends on a number of things. Wiesco's paperwork recomends .0025" for most applications but I would venture to say that clearence is more geared towards near stock power levels.

If you will be producing anything near 650hp you should really start to think about partially filling your block. Anything above this number without a filled block is playing with fire IMO. With a partially filled block and the power level you are targeting, I would shoot for .00375-.00425" PTW with Wiesco's pistons.

If you do not fill at all, and run a full water jacket, I would stay in the .00325-.00375" PTW range.

Full filled block, I would be up there in the .0045-.0055" range, but this would be for a dedicated track car.

These are numbers that I would reccomend for Wiesco's piston material.

Good luck.

 

[dsm-onster]

650hp on e85 is the same as 650hp on c16.

e85 keeps the piston crown cooler. Heat expands metal.

 

[4g64fiero]

Your Piston to Wall clearence really depends on a number of things. Wiesco's paperwork recomends .0025" for most applications but I would venture to say that clearence is more geared towards near stock power levels.

If you will be producing anything near 650hp you should really start to think about partially filling your block. Anything above this number without a filled block is playing with fire IMO. With a partially filled block and the power level you are targeting, I would shoot for .00375-.00425" PTW with Wiesco's pistons.

If you do not fill at all, and run a full water jacket, I would stay in the .00325-.00375" PTW range.

Full filled block, I would be up there in the .0045-.0055" range, but this would be for a dedicated track car.

These are numbers that I would reccomend for Wiesco's piston material.

Good luck.

Why would you have to partially fill your block? I thought these blocks didnt need to reinforced till over 1000whp? There are alot of guys running in the 700whp range with out a partially filled block.

 

[dsm-onster]

I'm wondering about this too. Not arguing one way or the other. Jsut seen too many unfilled 4g63 blocks daily beaten with 700-800whp. And those who've advised me on my eagle/wiseco build for my hx40 goals, everyone says that filling the block is for +900whp.

 

[awddsm95]

Its not a requirement, just something that people should start looking into doing when they are targeting above 650 whp. Cracked cylinders are not a fun thing to have happen (fortunatly it has not happend to me). I would just consider it extra reinforcement and assurance without any ill effects if done properly.

The more power you make, the more possibility of the block moving around. This can cause issues all around.

Im sure there are plenty of people that have pushed past that mark without even thinking about filling or partially filling the block. Its just my opinion. I think it will keep the engine straiter, cylinders more round, and help maintain ring seal.

 

[dsm-onster]

We'll just have to differ on the drifetrain loss. it takes the same amount of energy to spin the drivertrain no matter the power fed it. This is why the mass of cars goes faster down the track when we add more power. It takes 30ish whp to spin the drivetrain based on the difference between factory estimated by sae net power and whp on the dyno recorded for stock cars. The rest is heat right? 110whp is the loss you speculate: 110hp - 30hp = 80hp . That is nearly 60,000watts of heat? bullSHIT! To what wattage is your arc welder rated? At what energy does oil boil? There's no tranny alive that can tolerate that much heat in one run. . .

Thus, you don't need to worry about the energy converted as much as you're saying. There's not 20% more energy in a 650whp car moving around in the block.

 

[spoonman]

Like dsm-onster said in his post the fuel choice makes a huge impact on the Piston to Wall clearance. If you want to run E-85 and make 650WHP then a good clearance on a stock stroke engine with Wiseco pistons should run .00425.

 

[donniekak]

We'll just have to differ on the drifetrain loss. it takes the same amount of energy to spin the drivertrain no matter the power fed it. This is why the mass of cars goes faster down the track when we add more power. It takes 30ish whp to spin the drivetrain based on the difference between factory estimated by sae net power and whp on the dyno recorded for stock cars. The rest is heat right? 110whp is the loss you speculate: 110hp - 30hp = 80hp . That is nearly 60,000watts of heat? bullSHIT! To what wattage is your arc welder rated? At what energy does oil boil? There's no tranny alive that can tolerate that much heat in one run. . .

Thus, you don't need to worry about the energy converted as much as you're saying. There's not 20% more energy in a 650whp car moving around in the block.

Agreed. Drivetrain loss cannot be extrapolated from one data point in a linear fashion. A 200 hp engine with 25% drivetrain loss puts 150 hp to the wheels. Replacing the engine with a 1000 hp unit will produce more than 750 hp to the wheels.

 

[slowgsr]

We'll just have to differ on the drifetrain loss. it takes the same amount of energy to spin the drivertrain no matter the power fed it. This is why the mass of cars goes faster down the track when we add more power. It takes 30ish whp to spin the drivetrain based on the difference between factory estimated by sae net power and whp on the dyno recorded for stock cars. The rest is heat right? 110whp is the loss you speculate: 110hp - 30hp = 80hp . That is nearly 60,000watts of heat? bullSHIT! To what wattage is your arc welder rated? At what energy does oil boil? There's no tranny alive that can tolerate that much heat in one run. . .

Thus, you don't need to worry about the energy converted as much as you're saying. There's not 20% more energy in a 650whp car moving around in the block.

Watts is a unit for measuring energy.. not heat. So please, don't use it in that fashion, BTU's is better. Watts can be used to determine how much POWER, an electric heater draws.. but thats about it as far as 'heat' goes.. Whats is a measurement used to measure POWER, not heat.

Heck.. It is a straight conversion between HP and Power though I give you that, its like reading hydro meters in Horsepower.. hahah.. You just don't do it. Your house dosen't.

Then you compare the 60kw of power in 80hp to the amount of heat generated by an arc welder.. that comparison sucks too.

Now, If you want to say a stanard light bulb draws 90watts of power, 20watts is converted to light energy and the other 70watts is converted to heat energy I like that much better.

Efficiency is the word I like better for drivetrain loss.. It is rated in a percentage, just like electric motors.. generators etc. Heck.. a BIG motor and a SMALL motor might both be 95% efficient, 5kw and 500kw respectively.. That dosen't mean the 'lost' POWER in the large one (25kw) is converted ALL to heat energy.. There are many factors that decide efficiency ratings of things which im not going to get into.

Engine driving standard transmission ~ %10 (500 crank = 450 wheel HP)
Engine driving automatic transmission ~ %20 (500 crank = 400 wheel HP)

Efficiency of %90 and %80 regardless of power level.. It might only take 30hp to drive the gears at a specific power level which is a percentage of the input power, as the input power changes the power it takes to drive the gears changes, but the percentage of the input power to drive the gears stays the same. Its hard to explain.

200 crank hp is 180whp (20hp loss).. 90% efficient.
at 600 crank hp it wont be 580whp (20hp loss) It would be 540whp (60hp loss) still 90% efficient.

As power goes up, efficiency dosen't go up as well.. It says the same. If it went up you sir could make a lot of money..

Anyways.. Way off topic.

I ran 4 thous P2W clearance on my non filled block with weisco's.

 

[donniekak]

Drivetrain loss is not a simple 1 equation system. It does increase with power but, not in a purely linear fashion. Think of it this way, which is still an overly simple example, but should get the point across. At 200 hp and 20% drivetrain loss, lets say half of the loss is lost to rotational losses, and the other half to friction. Now, double the power. The total loss does not stay 20%. The portion of the loss derived from friction increases(not linearly), but how would the rotational losses increase, unless the gears got heavier, or increased in diameter?
As for the pistons, i don't like to use wisecos because of the coating on the skirt making it hard to get a good measurement for clearance. But count on it being close to .001".

 

[dsm-onster]

60000watts = 204728btus/hr. For a 10 second run, you're putting over 34000btus through the transmission if 80whp is lost through some other means other than moving the mechanical parts. What other ways is the energy lost? It isn't converted to light. It isn't converted to the strong force . Where is the conservation of energy fulfilled with a 75% efficient machine (146whp / 195crank SAE crank HP)? An all stock AWD dsm typically puts down about 175whp.

I heat my whole house with a 40000 btu PER HOUR stove. Assuming the law of conservation of energy applies to 'life in the 1/4 mile', this is 34000btus added in 10 seconds concentrated into 2 cubic ft. We're talking drivetrain loss and wasted energy outside the motor; not otto cycle thermal efficiency. Someone already made alot of money on it .

MY wiseco's are about .003". They are standard size off the shelf wiseco's with a block that has never been bored and only 103K on it. Only a hone put it at that spec. I think it's good enough per my talks with those far more experienced than me.