First Type IV build in 30 years

[cannuck]

Yeah, actually a bit longer. The last one I built was a 75x96 that never did get finished (might even be around in one of the storage units still). My air cooled days ended as business took me in different direction and used up all of my time. So, my best bud and I build a few strange things mostly because he has a pile of cash and I have a lot of experience and this is how we have fun. He decided he really "needs" a Speedster replica, but I just don't have the time to build a whole car, but I will gladly do the power train and spec all of the rest for the builder (Reisner/Intermeccanica) to supply a roller. To keep the flavour of Porscheness, I want to stick with 4 cylinders, air cooled and an engine that has at least SOME connection to that part of the company - i.e. Type IV. As I opened this thread explaining, my last time around Type IVs was a very, very different world from today, so I need as much help and advice as I can find.

Goal is 76 x 100 with some long-ish rods (I HATE high rod angles!!!!), carbs, electronic ignition in a distributor, some fairly mild heads (42 x 36 SS ??), aiming for enough compression to make some power, but still able to use the best of pump gas. Will go with DTM upright cooling, will try to squeeze a 228 mm forged flywheel into 901 bellhousing but can go 215 if that is all that will work.

Obviously the very first question is cylinders. Can I still get 100mm Birals? and where? Are they long enough to allow more than 2.0 rod dimensions without using shims or putting the pin in the middle of the rings? Is there another way of getting 100s? This is not a race engine, it is strictly a fun cruiser so reliability is the top of the list, but not sure we have the stomach for Nickie pricing.

All of the $600 forged cranks seem to be from the same supplier (assume Chinese). Are these proving good as supplied?

Probably 48s, not sure what venturi but need driveability. Might get lucky and find NOS DeOrtos, but not counting on that. The whole thing is to stay away from electronic injection to keep the vintage experience somewhat. Ditto why distributor.

Let's start here.

[wreck]

sadly 100mm P&C's are no longer readily available off the shelf as far as I know . A simpler build would be a 96mm x 78mm . No machining required . An option for 100mm cylinders would be a set of cut down and machined Deutz cylinders then find or get a set of custom pistons to suit .

[cannuck]

what Deutz engine?

[cal 67]

Just Google Deutz 100, or buy on ebay. They come long, and need a lot of lathe work and some milling. I bought some NOS Birals a year ago, and saw some a few months back, but they're rare. It's best just to step up to a 103, if you're not entering in a specific cc-limited class.

[subtaf]

I would like yo build a 76x100mm combo too. It's been discovered that the latish (~2006 I think) 5.7L Chrysler piston in the 1st oversize is 100mm dia and come with a 24mm gudgeon pin size. However, at 76mm stroke with stock rods these stop about 4mm short of the top of a stock length barrel. Good if you could get 5.325" rods to suit 24mm pin. Then machine up some Deutz barrels.

[wreck]

just make the deutz cylinders 4mm shorter and use the stock length rods , or 78mm stroke and 3mm shorter . I like the 100mm size because you don't have to machine the heads out through the holes for the head studs . it just makes for a stronger head .

[Wally]

just make the deutz cylinders 4mm shorter and use the stock length rods , or 78mm stroke and 3mm shorter . I like the 100mm size because you don't have to machine the heads out through the holes for the head studs . it just makes for a stronger head .

Well, I would agree more with the OP about the favourable longer rods option. New rods are cheap and even less then recondioning your old heavy originals anyways. Get the difference in a piston with much less deck height, which is also favourable.

But I am all with you on limiting the bore diameter for sake of strength in the heads as our stock style (and especially old original ones) heads, do and will warp and will have almost always sealing issues at the largest bores (103-105).

I was also very disappointed that AA has no more 98 birals in stock
Can't we as a group make a friendly sugestion that they get their ass in gear and make a new batch of 98 and/or 100mm biral cylinders again? pretty please?

Walter

[wreck]

the issue with the longer rods is the 22mm pin . I had a set of SBC pistons I wanted to use with my deutz cylinders but the 5.325 rods I got did not have enough material to safely bore them out for the larger pin .

[cannuck]

Sorry to disappear, but we weren't getting a confirmed and viable build date for the chassis, so I stopped worrying about stuff until I got the go-ahead from my client/friend. My trainee at main client left after receiving 5 years of intensive learning from me - only to get offered a stunning amount of $$$$ from a competitor, so my "free" time this spring is now shot to bits. So, I decided to go the cheater way out and buy a "kit" from LN to build a 102 x 78 with nickies and LE200 heads. Also, using DTM upright cooling conversion. This is all to end up as type 1 dimension fitting into a (Intermeccanica) 356 replica chassis/body hung on a 901 gearbox.

So, here come the detailed questions:
1. what compression ratio vs. fuel octane can this engine tolerate? Have shell 93 availavlable, not quite the 95 some places in USA get. From far, far distant past, I would have aimed for 10:1, but my gut is that I need to stop at 9.5 with today's non-ethanol fuel. Am I right????

2.What is the best available electronic ignition using distributor drive?

3. Had thought of going 44 IDF, but with this much displacement, I am thinking 48s with 40mm venturi will still be driveable. One of my friends runs 51s on 2.4 litre and seems to have decent driveability, so I am hoping to be on sound footing with 48/40.

4. The final one is WAY out in left field: to be able to register the end car, need heat/defrost system that works, thus want to use the stock 72-74 Type II heat exchangers, but with DTM cooling and 912 rear mount. Does anyone know if there is a muffler/exhaust system out there that will fit under the back of a 356 with these heat exchangers>???

[wreck]

There is a saying ,"don't put in what you can get out " Using stock exhaust heater boxes on a large performance engine is not a good idea . The exhaust will make or break the engine . Turbo Thomas or Tangerine exhausts may be able to help with a custom heater box set up . You will need at least 1 5/8 primary pipes for that size engine . 1 3/4 would be better . Give them the specifications of the engine and they will build an exhaust to suit .

The compression ratio is related to the cam shaft duration . Do a little research into dynamic compression . There are a few good online calculators .
I'm running 10.5 comp with a 274 degree cam at 0.050 on pump fuel .

a good distributor is a 123 programable unit . also sold by CSP as a peace maker and can be programmed by bluetooth .

The 48's are the best option . anything smaller will choke the head flow . A 48 DRLA with a 42mm venturi flows just under 200cfm per throat .

[Wally]

I totally agree with 'wreck'... especially don't 'under compress' it! You have nickies and awesome heads, they can tolerate a bit more CR and the resulting better overal hp and 'snappy-ness' is what you paid the big bucks for, don't throw that away

On a side note: is the CSP unit really an 123 unit under the skin? How did you find out?

[wreck]

I think I read something Torben Alstrup mentioned about the 123 and the CSP . Also on the CSP description it does state that they "took" parts from the 123 . It's only my guess that they have either used all the electronics of the 123 and just had them fitted to their own 009 style distributor shell , or just get the whole thing from 123 and re brand it .

[Wally]

That seems indeed a logical conclusion, tnx!
CSP (germany) is also located very close to the 123 headquarters (Netherlands)

[subtaf]

I was also very disappointed that AA has no more 98 birals in stock
Can't we as a group make a friendly sugestion that they get their ass in gear and make a new batch of 98 and/or 100mm biral cylinders again? pretty please?

Walter
[/quote]

Well count me in for lobbying AA for producing a 100mm Biral! They wouldn't even have to worry about pistons for them with the discovery of the 1st oversize 100mm 5.7 Chrysler piston already in production and suitable for the 24mm pin. If they got the base inner steel liner size & thickness right they could have a 100mm version for the Chrysler piston and then a thick wall 98mm / 22mm pin model that could be machined from the same base casting.
I'm still really keen to keep my next two builds at or under 100mm bore sizes because I know I'll be restricted to what I can do with AMC head castings. Also, I'm not planning to add 5th or 6th head studs.

[cannuck]

progress (or lack of) report.

Spoke with Bernd Bergman this week about his Type 4 cooling system..only to find out he no longer has the tooling. Is DTM my only option (that works, that is)?

Going to stick with my original 100 x 76 thanks to comments here and my reluctance to give up wall thickness in heads and cylinders and material from crankcase. My BIG question here is: what rod setup clears both the cam and case at this stroke?

Thanks to Wreck for the exhaust flow comments. That was bothering me to some extent, but I just needed a bit of a kick in the nuts to pull my head out of my ass on this one. Will call the recommended shops and see what they can do. Have to find out port size from L&N's head guy though.

I can vaguely remember from my distant past that the Type IV/914/912E used a 215 (Porsche) or 228 (Bus) flywheel with larger ring gear diameter, but for the life of me I don't remember the tooth counts and gear pitch for them. Am I correct in assuming the starter from any type I/II/III will fit the same hole and tooth pitch as II/IV/914/912??? Since we are using the 901 box, no problems with clearance for a 914 clutch, but the starter is a bit of a puzzle.

Also will be doing the 48IDF thing as this much displacement should still be quite driveable. My buddy at work is running 51 IDAs on his big type I buggy and finds it just fine - but it is worth knowing he also holds a handful of SCTA records so his idea of "just fine" might be a bit biased.