New Build 106 x 90 Making A 3.2 Ltr

[Type 4 Unleashed]

106.172 X 90 = 3187

The 90mm crank is about as large as you can get in a Type IV case and still get enough clearance between the int & exh lobes and the rods on 2 & 4, and still be able to get a nice size cam and thats with 1: 48 to 1 Paute rockers, to be able to feed such a large motor.


I picked up this 90mm Rabbit JRL crank. It's one of Scat's much older Forged units, and it was a Chevy JRL crank originally but for some reason reground to Rabbit JRL's with a 90mm stroke about 12 years ago, and thats all that's known about it.

Their have already been a couple of motors built there in Europe using a 90mm crank some time ago and that was with JRL Chevy's, so they do fit.

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And here are some quick mock up pics to see clearance issues.

These two pics show where the rods hits the case when it is rolled from the bottom & from the top.



These 2 pics show where the rod hits the lobe from when its rolled from the bottom & rollrd from the top.



So, there is a lot of figuring to do and a lot more mocking up to do.

But the biggest fix will be a set of Cunningham's made to fit Rabbit jrl's with the bolts flipped. I figure that if the Cunningham's will fit on a 90mm crank with a 2.0"-50.8mm jrl, then with the smaller by .200"-5.08mm Rabbit jrl they should provide close to .100".2.54mm of additional clearance between the case & another .100" between the cam lobes, if the outside dia. of the rods stay proportional to the jrl's dia. ?

The rod pictured in the mock up are from a set of 5.4" length Rabbit jrled Carrillo H beams. And were not the best coice for this mock up.
_________________
Richard

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[Type 4 Unleashed]

Here is some figuring I've done so far, trying to find a way to cut expense's.

And I came up with one of my old idea's, these are some rods I had pick up some time ago, they are new Lentz billet Nascar rods that I had got a deal on and they fit the 1.771" Honda jrl. The Rabbit jrl's are 1.8098" dia. and the size was verified on the crank so that checks out, and the mains check out to spec also. The width on the big end of these rods are .904" but are the earlier design and are off set style, the required width for the jrl's are about .890", so there's no problem bringing them to size.

The only problem I see with these rods are that they are 6.300' long and will make for a much wider motor, and that could be a problem fitting the motor in a 914 ? But the benefit of such a long rod, will provide a much better rod to stroke ratio of 1.78 to 1 with a 90mm crank, than running anything shorter.

I am going to use the Honda bearings that sre in these, I will machine them out to say .040" and that will be close to the running clearance and I can use the rods for mock up purpose's. And I am talking full mock ups here, cause I would like to use these rods in this motor if at all possible. If I can use these rods I will either have them re-sized to except the Rabbit bearings, which is what I would rather do, or if I have too I will turn the jrl's down to thw 1.771" Honda jrl. Or the only other rod option should these end up being too long, to spend the big money and have a set of cunninghams made, more than likely in a 6.0" rod but with only a 1.69 to 1 rod to stroke ratio .






_________________
Richard

WWW.CLUBNARP.COM
WWW.SHOPTALKFORUMS.COM

[70Turbobug]

Excellent Project! Remmele is also building a 106x90 using Deutz cylinders,an Arrow crank (british company that used to be an F1 supplier),Pauter rods on a type 4 big end and an 18mm wrist pin using very similar pistons that you posted recently.IIRC he is also only using a 5.7" rod,trying to keep the engine short enough for use with the common 14mm longer head studs.

I personally prefer a long rod ratio.Without going into a big discussion about that,there are simply comprimises that have to be made if you really plan on using a 6.3" rod.I personally would be a little nervous using anything above 6". Using the shorter rod would give the engine more snap,that may be lost due the long stroke.Proper headstud length vs. durability and expansion characteristics pose a lot of questions in terms of sealing,longevity and stability.It´s worth trying of course and is an area of interest.Cylinder length becomes a problem if you use type 4 cylinders like JE or AA.Deutz cylinders are longer,however require a lot machining to fit.Deutz cylinders are worth it though.There is no better cylinder period,in terms of hardness and stability and cooling.
_________________
Surgeon General´s Warning: This vehicle is equipped with a turbocharger and may cause spinal injury during acceleration.

[Type 4 Unleashed]

I have been thinking about this rod issue a lot, and have decided the 6.3 rods are just too long and make for issues that I don't want.

The head studs would not be an issue, I would need around a 1.250"-31.75mm cyl spacer, but use a spacer plate something like the pic, and use the stock studs mounted in the plate, then not having the issues you've mentioned.

But my main issue is the width of the motor fitting in between the rear suspension of a 914. Another is the additional length the push rods would need to be.

Now rod to stroke ratio's ? For a rod to stroke ratio comparison I use the Small Block Chevy, I also use the SBC for parts...

The 350 c.i. SBC motor has a 3.48"-88.392mm stroke, rods are 5.7"-144.78mm C to C which gives a 1.64 to 1 rod to stroke ratio.

The 400 c.i. SBC motor has a 3.75"-95.25mm stroke, rods are 5.5"-139.7mm C to C which gives a 1.47 to 1 rod to stroke ratio.

The 327 c.i. SBC motor has a 3.25"-82.55mm stroke, rods are 5.7"-144.78mm C to C which gives a 1.75 to 1 rod to stroke ratio.

The 302 c.i. SBC motor has a 3.0"-76.2mm stroke, rods are 5.7"-144.78mm C to C which gives a 1.9 to 1 rod to stroke ratio.

The capabilities of the SBC are well known, the 302 & the 327 are well known for being able to pull high rpms 8,000 & higher, the 350 is known for pulling at least to 8,000 rpm, and the 400 usually between 6,000 to 7,000 rpm.


So a 90mm - 3.54" stroke isn't very much larger than the 350 stroke. But with a 5.7'-144.78mm C to C rod it will have a 1.61 to 1 rod to stroke ratio, compared to the 350 c.i. motor which had a 1.64 to 1 rod to stroke ratio.

So a 90 stroke with a 6.0'-152.4mm C to C rod has a 1.69 to 1 rod to stroke ratio and with the 6.3" rod it was 1.78 to 1.

And about your one comment ? The 327 SBC with a 82.55 mm stroke and a 1.75 to 1 rod to stroke ratio had some pretty good snap.

So I have been thinking of a rod length between 5.7" & 6.1", but I would like to be in the 1.7 to 1 ratio area.

Then there's compromise, an issue that also has to be delt with...






Side Note:
The 6.3" rods, while I was trying to find a way to use them on the 90mm crank, I was able to determine I can have them re-tanged & re-sized to except the Rabbit bearings, and now that I have decided I can't use them on the 90mm crank, I have found I could use them on an 80mm with a rod to stroke of 2.0 to 1, or possibly a 82mm stroke with a 1.95 to 1 ratio...
_________________
Richard

WWW.CLUBNARP.COM
WWW.SHOPTALKFORUMS.COM

[Johnbitch]

my technical english isn`t good enough yet to understand everything, but it seems not too bad to me what is happening here I wonder if i should quit building 1200cc type 1 engines

It is amazing for me to see that it is possible to use v8 parts for Type 4 engines It is a little bit the same with me using motorbikeparts for my 1200cc.

I`m waiting for the next steps and the next pic`s

[70Turbobug]

All true Richard,and I know that the Chevy engines and other V8 engines work well with short rod ratios.However,they also have tremendous side load on the pistons.This would be even worse on a boxer engine,due to the opposed cylinder design and crank design.
If I were to make cylinder spacers,I wouldn´t make a plate as in the pic above.I would cut/maschine round cylinder spacer/barrels for each cylinder.Remmele has had the best results with that method.The problem with the plate is,it is too rigid and doesn´t move and expand with the case.Which leads to warpage on the head studs and sealing issues.The longer the head stud,the bigger the problem in that matter.
_________________
Surgeon General´s Warning: This vehicle is equipped with a turbocharger and may cause spinal injury during acceleration.

[Type 4 Unleashed]