Hi folks. I have had some great success with my fuel injected turbocharged Slant 6 using low comp dished cast pistons... I have had 20 lbs boost into these suckers and they are showing a greeat resistence to the beeating I have put them through. I am now on the hunt for serious power out of my Slant and have been looking at forged piston alternatives.

Has anyone used VW flat four pistons with any success ? ... I have just ordered a set of 88mm mahle forgings and another experimental set of 90.5mm. From what i have researched the compression height is slightly lower on teh 90.5mm piston... this may very well require sleeving for use but a 4.0 litre Slant sounds like a good thing. For now I will be using the 88mm items with 198 rods, they are a floating piston also but so far all is looking pretty positive.

Any thoughts on this would be great.

Ray.

I believe the fin (Jyri?) used vw pistons?

Now, Ray, I'm not gonna accuse you of anything, 'cause that wouldn't be neighbourly, but if I were, I'd probably say it sounds a lot like you're bragging, mate!

Seriously, keep posting the good stuff on your car. It's great to see.

After seeing Ray's car up close a few times I think he has every right to brag about it (not that he does)
It's a very tidy unit with a lot work and $ in it. I will watching with interest to see how it runs on the 1/4 with the next build.

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Richard (aka Fingers)

DEFINITELY!

Thanks for your replies....

Dan : No not bragging, I just think it's incredible how well these pistons are holding up... and when I said "great success" I was really paying homage to the greatness of our beloved Slant 6 engine and it's willingness to be boosted ! I am but a newbie to the Slant 6 phenomenon, only six years young...but hooked like all our SL6 junkie bretheren.

I have had many conversations with Jyri, he has been of great assistance even though there is an obvious language barrier. In fact I purchased my 198 rods off him recently already bushed to accept the VW gudgeon. Now that I have these rods I have had the opportunity to research the viability in remanufacturing them... as it turns out i can have them made but as with most things they are quite costly @ around $1500 AUD per set.... but they will be almost bullet-proof. More on that later.

I would like to know if there has been any other recorded use of these pistons as an alternative for the lack of forgings for Slant 6 engines. This is the avenue I have chosen to take with my new build and i will definately advise of outcome, power figures, 1/4 mile times and most importantly to me driveability.

My car is my daily driver, but I still love having fun in it. This is the second engine I have built for the use of injection/turbo, the first one suffered from serious cam-walk, which I never before seen on a Slant, but is an inherent problem with our Hemi 6 engines here in Oz. With this current engine I have taken measures to ensure that problem is resolved. The first build was really a test bed for the basics... still made pretty good power for a "throw-together" @ 220 rwhp and a copius amount of torque. It was all junkyard peices really, modified and tidied up to look the part...fancy that it made really good useable power. It has not been shy of it's fair amount of issues though...a blown head-gasket during burnout comp and my current setup has shown obvious flaws in air distribution, I have problems with the front throttle body leaning out....once seizing #1 exhaust valve open.. ( again during a burnout comp )... but other than that it has been fairly reliable, considering the hard time it gets...

I havent really spent much time here on this board as I am pretty tied up with my own Australian based web presence ( http://www.moparmarket.com).... but if it's ok with you guys, i'd love to spend more time here from time to time....

Oh, by the way I also have a restoration business here in Sydney that specialises in the preservation of Classic Mopars, we manufacture components to assist in the restoration of these cars... I mention this because we are currently making an intake manifold for the Hemi 6 that is very simliar to the Hyper_Pak Slant intake....this will be complete in around 6 months time, we are then going to make a 4 barrel intake for the Slant, very similar in design to the Hyper-Pak but incorporating injection facilities also.... just thought you folks might like to know about that as info comes....

Thanks.

Ray

Well, why not? You should be! Your work on the Val is stunning.
Yes, more later please! 198 rods are getting tough to source.
Nightly, too? You should have a set of these, compared with standard sealed and H4 items here. The ones on my site are wrong-side-drive, but I can get you the P/Ns for RHD.
Yes, please do!
Whom do you like for repro lenses? I'm talking with someone in OZ about '62 Lancer lenses (not Azzopardi; don't like his stuff).
Nifty stuff, keep it comin'.

(How 'bout an alloy head w/newer-than-stone-age combustion chambers for the slant...?)

If cast pistons handle 20 pounds you're doing something
right. I don't think diesel truck motor pistons would last
long should serious detonation occur. 20 pounds is a lot
of boost.

Yeah, i would not have thought the pistons would hold up to this kind of abuse either.... I have damaged number 6 after I blew the head gasket ( it blew from cylinder to rear tappet gallery. ) but I am guessing that was from driving it home afterwards, even if I was crawling. It has minor pitting in the top of the piston now, but I replaced the gasket and bolted the head back on to see how it would go. I am very impressed. These pistons are no longer available but was fortunate enough to buy two 0.40" sets a couple of years ago cheap from a closing dealer just labelled "Slant 6 truck". I recently found another set at a swap meet for $80 ! .... I love these things.

Also, has anyone tried fitting wet sleeves for larger replacement pistons.... I am thinking of these 90.5mm forgings for a wicked 4001cc normally aspirated Slant monster. Thoughts ?

You may well run into trouble with the single-thickness wall that separates the camshaft from the bore area...this is what doomed the plan to increase the slant to 246 CID in '67; the beancounters nixed the block casting rework.

Lots of racers are boring up to 0.130-0.140" over (sonic check) and some running without block filler. 0.100" over is very common.

Still won't get you 90.5mm, but just some info for ya.

Lou

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