mitsuturbo
Well-known member
I wanted it in writing, so i got it. Here is my exchange with Mahle regarding their 4032 forgings for a 4g63.
</font><blockquote><font class="small">Quoting mitsuturbo:</font><hr />
I'm looking for some help with Piston To cylinder Wall clearance on a set of pistons i purchased. The machine shop i took my block to decided to put it at .006" because the bright green spec sheet included with the pistons says to set PTW clearance at .0025 to .0030" and add .001 to .003" for applications such as forced induction, filled block, nitrous. Since this is going into a turbocharged car, they put it at max. PER YOUR SPEC CARD <img src="/ubbthreads/images/graemlins/frown.gif" alt="" /> Everything i've known in the past, am hearing and reading now, says that this is WAAAAY too big. This engine is going to be running in a (primarily) STREET CAR that will peak at about 24psi of boost most of the time. It "might" see 30 or a shade over PSI if i ever decide to run some leaded fuel and take it to the track.
The pistons are model MIT367385i13 (4g63 turbo, with 13cc dish for 3.386 bore) I've already pulled another block in order to get this right, as .006 seems way too sloppy. Please advise.
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</font><blockquote><font class="small">Quoting Tony Ford @ Mahle:</font><hr />
Talked to you last week on the phone about this. 0.006" is too much clearance for those pistons. You need to finish the bores on the new block to Ø3.3855".
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</font><blockquote><font class="small">Quoting mitsuturbo:</font><hr />
I relayed this information to the machinist, and he's since expressed concern, stating this only allows for .0018" clearance. He's asked if this is acceptable, stated that the included documentation with the pistons states otherwise, and is wondering if the coating is somehow a factor in the bore size vs PTW clearance. He's asked if maybe he's measured the piston skirt in the wrong area. I expressed that these are very low expansion pistons and factory spec is .002" on the extreme loose end. Still he seems to think “that's not enough clearance" if you're going to be running 20+ pounds of boost. I think I'm comfortable with .002" but any clarification you can offer would be helpful.
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</font><blockquote><font class="small">Quoting Tony Ford @ Mahle:</font><hr />
The actual clearance is goinn to be 0.0035", but you can't measure that, because they're coated. We count our clearance to the aluminum.
That should be plenty of clearance.
I designed these pistons, and have prescribed the specifications to hundreds of people. No complaints.
Kind Regards,
Tony Ford
MAHLE Engine Components USA, Inc.
MAHLE Motorsports (IMO7)
270 Rutledge Road, Unit C
Fletcher, North Carolina 28732 USA
Phone: 1 (828) 650-0814, Fax: 1 (828) 650-0819
[email protected], click
<hr /></blockquote><font class="post">
Edit: noticed some characters weren't showing up right, such as the Ø and some quotation marks
</font><blockquote><font class="small">Quoting mitsuturbo:</font><hr />
I'm looking for some help with Piston To cylinder Wall clearance on a set of pistons i purchased. The machine shop i took my block to decided to put it at .006" because the bright green spec sheet included with the pistons says to set PTW clearance at .0025 to .0030" and add .001 to .003" for applications such as forced induction, filled block, nitrous. Since this is going into a turbocharged car, they put it at max. PER YOUR SPEC CARD <img src="/ubbthreads/images/graemlins/frown.gif" alt="" /> Everything i've known in the past, am hearing and reading now, says that this is WAAAAY too big. This engine is going to be running in a (primarily) STREET CAR that will peak at about 24psi of boost most of the time. It "might" see 30 or a shade over PSI if i ever decide to run some leaded fuel and take it to the track.
The pistons are model MIT367385i13 (4g63 turbo, with 13cc dish for 3.386 bore) I've already pulled another block in order to get this right, as .006 seems way too sloppy. Please advise.
<hr /></blockquote><font class="post">
</font><blockquote><font class="small">Quoting Tony Ford @ Mahle:</font><hr />
Talked to you last week on the phone about this. 0.006" is too much clearance for those pistons. You need to finish the bores on the new block to Ø3.3855".
<hr /></blockquote><font class="post">
</font><blockquote><font class="small">Quoting mitsuturbo:</font><hr />
I relayed this information to the machinist, and he's since expressed concern, stating this only allows for .0018" clearance. He's asked if this is acceptable, stated that the included documentation with the pistons states otherwise, and is wondering if the coating is somehow a factor in the bore size vs PTW clearance. He's asked if maybe he's measured the piston skirt in the wrong area. I expressed that these are very low expansion pistons and factory spec is .002" on the extreme loose end. Still he seems to think “that's not enough clearance" if you're going to be running 20+ pounds of boost. I think I'm comfortable with .002" but any clarification you can offer would be helpful.
<hr /></blockquote><font class="post">
</font><blockquote><font class="small">Quoting Tony Ford @ Mahle:</font><hr />
The actual clearance is goinn to be 0.0035", but you can't measure that, because they're coated. We count our clearance to the aluminum.
That should be plenty of clearance.
I designed these pistons, and have prescribed the specifications to hundreds of people. No complaints.
Kind Regards,
Tony Ford
MAHLE Engine Components USA, Inc.
MAHLE Motorsports (IMO7)
270 Rutledge Road, Unit C
Fletcher, North Carolina 28732 USA
Phone: 1 (828) 650-0814, Fax: 1 (828) 650-0819
[email protected], click
<hr /></blockquote><font class="post">
Edit: noticed some characters weren't showing up right, such as the Ø and some quotation marks
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