PTW Clearance For A 400whp Daily Driver

[spadepro22]

What ptw clearance should I run? This is a dd and I'm shooting for 400-450whp. I know Wiseco is a common piston used in our community but is Manley or Mahle a good piston to run? My builder says I should go .005.

 

[Archer Fabrications]

I'm runnin forged mahles and love them, dynod 392 at 22psi on pump gas and they held fine. I'm on 28psi same turbo still no issues. The mahles are great because they are low expansion metal. However they might be sketchy above 550. Thats what my builder said. If you ever want over that wiseco or ross are pretty safe bets. I'll probably end up with ross/tool steel rods next. My motor has 9.5k miles on it and running strong! Sorry i can't help much with the clearance.

 

[arrowhead]

Go by manufacturer specs.

There are small variations, even depending on type or alloy use it is not a set number and also it is not a mystery.

 

[TSIfreek]

I run mahles as well. I was impressed with the piston design and beefy pins that come stock. I am running real tight PTW and have had no problems with great oil control.

 

[WES_393]

All of the info you need will be on the included tech sheet. I'm running Manley pistons at about .004 ptw clearance. Since the skirts were coated, the cylinders were only honed to .0035 clearance so they would end up around .004" after break-in.

But Manly pistons are really good for the price. Even my machinist was impressed by the visual quality. I plan to put down over 500whp this Spring and the last thing I'm worried about is my Eagle/Manley combo.

 

[DSMnoobsause]

best thing to do would be to contact the manufacturer of the pistons and tell them what your plans are. they can tell you the recommended clearances.

 

[Lou98GSX]

runing eagle manley with .040 over bore no problems .dsmlink showed over 400hp on 2nd gear pull at 26 psi with meth.

 

[RvlutionMtrsprt]

^ What does that have to do with piston to wall clearances?

OP, your PTW clearances will vary with different manufacturers. Some will recommend as low as .0025-.003. I think .005 is a little on the loose side for 400-450whp. If that's the limit of what you're going to shoot for, I'd run .003-.004 as long as that is within the manufacturers specifications. I ran off the shelf Wiseco's at .005-.0055 on my last build (550whp). If you don't mind spending a little bit of extra money for peace of mind, buy a set of Wiseco HD's and rest easy that you won't have to worry about piston strength one bit at that power level.

 

[MichaelSuch]

.004 PTW with regular Wisecos, dyno'd 501whp. E85 @ 26psi

 

[spadepro22]

^ What does that have to do with piston to wall clearances?

OP, your PTW clearances will vary with different manufacturers. Some will recommend as low as .0025-.003. I think .005 is a little on the loose side for 400-450whp. If that's the limit of what you're going to shoot for, I'd run .003-.004 as long as that is within the manufacturers specifications. I ran off the shelf Wiseco's at .005-.0055 on my last build (550whp). If you don't mind spending a little bit of extra money for peace of mind, buy a set of Wiseco HD's and rest easy that you won't have to worry about piston strength one bit at that power level.

Seems you made good power at .005-.0055. Say I wanted to make more power down the road, how would .005 affect me in the meantime around the 400whp?

 

[viperlp01]

Your confused. It has to do with the expansion of the material as it is exposed to heat. The more power means more heat which will sometimes require more clearance. .0035-.005 is good from stock to 600 HP. Generally you run more when you have a filled block as the block can not expand at the same rate as the piston...

With that being said pistons are made of different materials and designs. On the spec sheet is a recommended PTW clearance. That number is important. If it recommends a .0024 PTW clearance and you want to run .005 and your machinist does not have a torque plate you may just experience some slap. Not likely but possible. Honesty trust your machinist.

 

[RvlutionMtrsprt]

Expanding just a bit on what john wrote... The only downside to running the larger clearance on a lower HP motor is a little bit of oil consumption between changes. Less power generally means less heat and less expansion. Larger clearance with less expansion is what gives you the possibility of some oil consumption. Not a lot, maybe a quart every oil change.

 

[spadepro22]

So would it be safe to say that .004 ptw clearance is a good number? Not too loose and not too tight?

 

[RvlutionMtrsprt]

Depending on the pistons you choose, that should work just fine for your 400-450whp goal.

 

[bryanwheat]

I would go by what the manufacturer of the piston recommends and nothing more. Because of the different material used in each piston each will have a different expansion rate.

 

[RvlutionMtrsprt]

How many manufacturers do you know of that advertise PTW clearances knowing that the engine will be running 2-5x its original horsepower? As far as I know, none. They advertise PTW clearances appropriate to the metallurgy as compared to stock. If you try running the manufacturer recommended clearance of .0025-.0035 on a motor making 600-800whp I don't think you're going to enjoy the results. As John said, trust your machinist. Hopefully you have picked one that is familiar with high HP 4g63 engine builds and can set the motor up accordingly. Not trying to say you're not knowledgeable but I completely disagree with that recommendation.

 

[blackrosenova40]

Also when you have your block bored and honed, see if they have a torque plate. Using it will allow a small amount of tighter clearances as your cylinders will be more true.

 

[spadepro22]

So, I went with Wiseco 1400hd and its decison time. My builder says I have .004 now, should I say there or go .045 or .005? I just don't want to get piston slap.