Mythbuster: continuing project thread of my 1303 '75

[Wally]

Originally Posted by 70Turbobug

Why the 1.5mm restrictor?

1.5mm or AN3 line feed.
Its prescription from Airwerks Borg-Warner. Same as large frame Garrett non-ball bearing turbo's

[70Turbobug]

Learn something new everyday! So this one isn´t ball bearing either?

[Wally]

Originally Posted by 70Turbobug

Learn something new everyday! So this one isn´t ball bearing either?

Nope, no ball-bearing. Would have loved to have that in there as well though, but these models just don't come with them.
The twin-scroll should provide the quicker spooling. When tuned right (header sizes), these spool as 'fast' as a Garrett 35R does with a little more hp under the curve, but for less then 2/3 the Garrett BB price tag

[70Turbobug]

If you have the same spooling time as with the old turbo but more power and ability to keep the boost level in the high rpm aswell, then it was worth it imo.The BB turbos are nice,but like you said so much more expensive.You would have to ask yourself if the advantages of the BB outweigh the price tag.

[Wally]

Originally Posted by 70Turbobug

If you have the same spooling time as with the old turbo but more power and ability to keep the boost level in the high rpm aswell, then it was worth it imo.

This turbo is NOT a logical 'upgrade' for this engine!
I am sure spool is much later now, as this is a TOO large of a turbo for this engine/application. A comparable BB turbo of this size would also have later spool, but like I said before: this turbo was NOT ment for this engine, but a much larger one
Still I am very curieus what this will do on this 2.2 engine as I have so much data on this engine already.

Only if you look at a drag racing application, this turbo could do well if the cam could support the flow/rpm. For pure drag racing, the cam is not optimal either though..

As always, its a big compromise as it is.
It is tempting to completely disassemble the engine and do a cam swap, just to give it drag racing caracteristics and really let it rip at the strip
Not for now anyways, I have a hard time thinking how to install this turbo as it is

[effvee]

Originally Posted by Wally

This turbo is NOT a logical 'upgrade' for this engine!
I am sure spool is much later now, as this is a TOO large of a turbo for this engine/application. A comparable BB turbo of this size would also have later spool, but like I said before: this turbo was NOT ment for this engine, but a much larger one
Still I am very curieus what this will do on this 2.2 engine as I have so much data on this engine already.

Only if you look at a drag racing application, this turbo could do well if the cam could support the flow/rpm. For pure drag racing, the cam is not optimal either though..

As always, its a big compromise as it is.
It is tempting to completely disassemble the engine and do a cam swap, just to give it drag racing caracteristics and really let it rip at the strip
Not for now anyways, I have a hard time thinking how to install this turbo as it is

Hi Walter, I have noted your up-grades and congrats. Question, when is enough on your current engine, before you have a major failure? You have done very well, I'd hate to see you engine let loose.

[Wally]

Originally Posted by effvee

Hi Walter, I have noted your up-grades and congrats. Question, when is enough on your current engine, before you have a major failure? You have done very well, I'd hate to see you engine let loose.

I hear you! But that is also the nature of me: I'd like to improve untill I think there is no gain to be had. And imo there are still loads of thinks to improve upon and the type 4 case is much stronger than 400 hp. Swedish lunatics (and I mean this in a kind way ) have gone 600+ on the type 4 casing with a drag-race-only engine, so I think there are possibilties to extend that to track-driving with a little less hp, but for longer duration

The car itself is still very drivable too. Its not scary when you step on it, so also because the handling can handle it, I think more power is possible.
If I can keep it 'in tune' (and I am getting rather well at this, even if I say so myself), there is no reason it should break with more hp, although I am getting more and more surprised the alu cylinders keep up

Another thing to consider: this (much) bigger turbo is more gentle on the engine at comparable boost then the smaller turbo was due to lesser backpressure...
So more power at less stress for the engine! How can you pass up on that?

[70Turbobug]

So Walter, if I am reading between the lines correctly...you´re planning on a larger engine?

[Wally]

Originally Posted by 70Turbobug

So Walter, if I am reading between the lines correctly...you´re planning on a larger engine?

Of course! But that will take a while as its a lot of $$. The stroker crank however has already been 'heat treated', a forged (stock 914) flywheel seems to be able to be used for 228mm enlargement and a set of 'virgin' 914 2.0 heads is in storage for some time already to get the 'treatment' once funds are available
After all, the current engine was only made from left overs of the 2,7 carnage and therefore not 'all i can be'...

[70Turbobug]

Sounds good! I think the heads you have now will do just fine.Or are planning with bigger valves and welded ports,etc.? You could sell your current engine,that would give you enough money for the next build.I´m sure you would find a buyer for it.

[Wally]

Originally Posted by 70Turbobug

Sounds good! I think the heads you have now will do just fine.Or are planning with bigger valves and welded ports,etc.? You could sell your current engine,that would give you enough money for the next build.I´m sure you would find a buyer for it.

I agree: the current heads flow well, even with just 0,500" valve lift. The 'new' set would be about the same, but with a tiny bit more porting, maybe Be-seats and upgraded valve train package. They would have a little more beef left in the heads as I would start with virgin heads and like a bit more CR, so they would get a little better in all aspects. Then a cam with more lift and you have more potential. At least thats my thinking.

I don't think I want to sell the current engine as I can use lots of its parts from it and I am VERY curieus how its looks on the inside. Only if I can see what it looks like will I be able to judge how well certain solutions have worked out.
But thats all in the far future due to $$ needed

[effvee]

Originally Posted by Wally

Then a cam with more lift and you have more potential. At least thats my thinking.

Walter, in regards to more cam, how about a set of Pauter ratio rockers in the mean time. I believe that would allow a sort of more cam/results for a short investment. And later you can still use the ratio rocker in your next build?

[Wally]

Originally Posted by effvee

Walter, in regards to more cam, how about a set of Pauter ratio rockers in the mean time.

That would give too much lift with this cam... its a fine balance

[1302 S]

Hello Wally
I like your combination of short stroke and large bore in your engine. And it seems to be very realibly, you have realy succeeded.
I have read your thread but I cant find what valve size you use in your heads? I could have missed something....

// Anders

[70Turbobug]

I wanted more "beef" on the exhaust ports,since that is a weakspot imo.That´s why I chose the CU heads.They have a thick chamber and enough room for big valves.The square ports allow a better seal at the header.I´m also curious what your motor looks like inside,mainly the cam and lifters.The crank and rods will be fine I´m sure and should show little wear.I´m anxiuos to see what size engine you will build.