FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: bluef100fe on August 21, 2020, 10:54:28 AM
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Are they any good. Anybody use them in a road race application? Looking for something with 20 or so cc dish and 4.130/4.135 bore, 4.25 stroke 6.7 rod. TIA
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Brent or Barry can hook you up on a set. With a 4.250 stroke and road racing in mind , I don't forsee rpms over 7,000 so the Autotec will be fine. -20 can be done and "any" bore size can be made. Autotec pistons are made from 4032 (high silicon) forgings. That material is used because it is a "low expansion" aluminum as opposed to 2618 also used. The original TRW material used by Ford for all of it's forged piston was MS75 , a similar alloy to 4032 ( high silicon) Mahle also uses 4032 alloy for many of their pistons , and JE's SRP line is 4032. Autotec is the only company I know of that does "custom" 4032 pistons.
Randy
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I not sure if you can get the bore size you want in a Mahle but one of their 4.05 +.03 pistons for stroker apps have -19 cc. That is what is in my 445. Teflon skirts, modern ring pack. Just in case you need possible options.
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They sure looked pretty when they went in my 428.Way overkill for my usage but what the hell.there was some problems but i things were corrected as they should thanks to Brent and Randy(gth350hr if i understood right).
Way fast service anyway,im in europe so if get Something in month thats fast.
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I have been extremely happy with Autotec, however, if it is a very radical and high rpm motor, I may consider the Racetec 2618s. If under 7000 rpm likely no need, but if a real radical runner, 2618 may match better regardless of brand
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We could (and have...) spent a lot of time debating and discussing the comparative merits of 2618 versus 4032. Randy is closer to current technology, my data would be somewhat dated at this point.
The silicon content of 4032 has some advantages that were very important to OEM automotive and marine applications. Silicon improves durability of skirts, pin bores and ring grooves for extended use applications. The 2618 has greater high temperature strength and ductility - important in a race environment where a part may run at - or even beyond - it's design envelope. The growth rate is different, but skirt clearances are at least as dependent upon oil groove drainback design and skirt profile as they are on materials. Modern design capabilities, tuning ability, and coating technology allow the differences between the two materials too be minimized if not completely adapted for. I have seen 1000HP+ 4032 engines and 70,000+ mile 2618 builds, neither of which were imagined possible 20 years ago.
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Waaay back in '75 , I "tested" 4032 alloy for BRC Pistons which was here in CA at the time. I ran the pistons in my 9,000 rpm Boss 302 and they were fine with the short 3" stroke UNTIL I had some valve to piston issues caused by failing valve springs on a roller cam. Back then springs were no of the same quality we have now. Valve interference caused a piston to literally shatter into many small pieces. That was when I learned about the reduced "ductility" of 4032. The forged material is strong but "like glass" when it goes beyond it's "yield point". In the proper scenario ( as Barry said) both 2618 and 4032 work very well. As I mentioned several companies use 4032 regularly and there are MILLIONS in use.
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... caused a piston to literally shatter into many small pieces. That was when I learned about the reduced "ductility" of 4032. The forged material is strong but "like glass" ....
You ain't lived until you get to see a hypereutectic piston that saw piston to valve contact at high RPM.
You get "Cup O' Piston" where there is not a single piece larger than the eraser on a pencil....
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Barry ,
20 years ago when I was involved with the development of the narrow pin boss/"box" design pistons ( 2618 alloy) I had those on a weekly basis from Nascar teams. That was a very steep learning curve on that deal! Now everybody uses them. Two or three times a year I get one that was forged with dynamite in it LOL.
Randy