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type iv connecting rods

I've got too many projects going now, so I have various engine parts laying around, specifically an open 350 hopped up chevy, 2.0, 1.7, toyota 5mge from an 85 supra, and a type 1 rod and 924 (i think) pistons lying around. I brought them all together to study the differences, and boom-- it hits me like a ton of bricks, the 2.0 rods are heavy as heck. shorter, fatter, and heavy (boat anchors, says one guy of STF). I guess that makes them stronger, but all that reciprocating weight must have a big effect on the willingness of the engine to rev, i would think. Or is that all in my head?

I know type 1 rods are an option now. How would I feel the reduced weight of the rods in my driving experience.

Also, with all the aftermarket vw stuff available, why isn't there a bolt in type iv lightweight performance rod made by anyone?

Inquring minds want to know.

PD
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72 914 2056: 74 9146 2.2: 76 914 2.0
Old 11-14-2002, 05:22 PM
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I've got T1 rods in my 2270, JE pistons, lightened flywheel, you name it.

It's rather "snappy"

I have videos to prove it, email me off list for them.

Later,
Tom
Old 11-14-2002, 05:35 PM
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The reason there isn't a lightweight bolt-in rod that's popular is that it's just as easy to put a stroker crank in there when you go to Chev or Type I journals on the crank...

--DD
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Old 11-14-2002, 05:57 PM
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I've seen the vids. I think it changed my perspective on the stroker motors, now I want one.

Hey, if you can't find a better 914 than the one in your other post, I'm sure we can find you one here in Texas. You might spend 2 days driving, but you'll save lot's more than that in restoration time
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72 914 2056: 74 9146 2.2: 76 914 2.0
Old 11-14-2002, 06:02 PM
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In our SCCA GT3 motors way back (when we couldnt afford Carrillo's) we lightened the factory 2.0 rods by almost 50 grams (This is a lot) They looked like paper weights for your desk. They lasted 2 years in the engine.

Look at the small end of the rod and imagine half that material gone.

Any time you can remove material from reciprocating or rotating parts.. you will get a engine that revs a little faster.

NOW. Check your rules. I happen to know your PCA region doesnt allow for material to be removed from the rods except for balancing purposes in the stock style classes. They also dont allow anything but a steel rod. None of this matters if you dont plan to AutoX or Time trial.

B

Last edited by Brad Roberts; 11-14-2002 at 08:08 PM..
Old 11-14-2002, 08:05 PM
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There is a lot of excess to the 2.0L rods, the 1.7/1.8's are even more.

The nice part about T1 rods are they are a bit longer and give a better rod ratio, the leave the piston at TDC for a bit longer.

Plus, it makes assembly easier.

From an economic standpoint, look at this...

ARP 2.0L rod bolts are around $140
SCAT T1 I-Beam standard rod can be found around $160-170
Add ARP bolts for $40 (I believe).

But, I don't have to worry about rulebooks, so that's not a huge deal for me.

Hope this helps,
Tom
Old 11-15-2002, 04:36 AM
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I'm in the process of a 2056 buildup right now and my reasons for not doing a stroker, and keeping the 2.0L rods were as follows:

I had a good crank and rods.
I would need to buy a new stroker crank w/T1 journals
I would need to buy pistons with raised pin height and 22mm wrist pins.
I would need to buy new T1 rods with new bolts.
I would need a reduced base circle cam.
My valve train geometry would get more expensive.
I would need BIG valves and even more head work.


It's a tangled web. The decision to push for a stroker really starts to add up. I plan on a 2270 for the future, but for now I'll try my hand at a 2056. I am upgrading the rod bolts to the ARP ones ($105 at Summit), but that's about it for the changes to the bottom end. A bit of headwork (slight valve increase), and a streetable Webcam 86.

Tom's stroker is a truckload of fun (I've driven it, and the videos do not do it justice), but it cost him headaches and lots of $$$. Still, it is definitely worth it. I just can't swing that right now.

Later,

G
Old 11-15-2002, 05:04 AM
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The almighty $$ is what is keeping me from changing, I'll keep my 2.0 rods, I'll put in new rings, bearings and an 86 cam. I'll clean up the heads and be happy with 100 hp. Remember, I've driven stock 50 hp VW's for 25 years, so 100 hp is a windfall of power. You could probably gain as much from balancing everything and lightening the flywheel, much cheaper.

Randy
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Old 11-15-2002, 06:01 AM
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I had my numbers wrong, I thought those ARP bolts were $140, must have been something else. My bad...

I agree completely, the money does make the difference.

Now, I needed a CW crank and it's the same price for a 71mm as a 78.4, so.... You know the rest. Free cc's? I'll take it.

In reality, I could have had one of my 66mm cranks reground to a 71 and use my 2.0L rods and made a 2056.

The relationship between motor size and price is not always linear (unfortunately), it's more exponential...

Good, fast, or cheap... Pick any two.

Later,
Tom

Last edited by Tom Perso; 11-15-2002 at 08:50 AM..
Old 11-15-2002, 08:24 AM
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You can't pick fast and cheap can you?
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Old 11-15-2002, 08:46 AM
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Sure you can! Those motors are called "grenades". Slap it together, it'll go fast. For about 15 feet.


Good, fast, or cheap... Pick any two.

Pick at most two. Far too many places will give you only one of those three, and some won't give you any of them....

--DD
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Old 11-15-2002, 08:51 AM
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Oh, and to clear one item up:

2.0L rods are NOT short. Maybe in comparison to a T1 rod, but not compared to a 66 stroke rod.

66 stroke rod 126mm
71 stroke rod 131mm
T1 rods 136mm


Yeah, they are heavier, but if you replace the bolts they are damned near indestructable (within reason of course).

My motor will be good, somewhat faster, and not incredibly "cheap" (unless $2k is your idea of a cheap rebuild).

Later,

G
Old 11-15-2002, 10:22 AM
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Cool

Here's some pics of the rods I was comparing.

from left
Toyota I6, 2.8l 6250 redline
chevy 350
type 1
type 4 2.0 l

now this is small sample for sure, but it struck me how much beefier this rod is for a cylinder producing 25 hp compared to the others making more per cylinder (except the type 1).

I've since wondered if it's because it's in a motor with a short stroke (relative to the others) so it's at a mechanical disadvantage to make torque when the mixture explodes.

Anyway, I've got to balance them anyway, I may do some creative balancing along the way.

Still surprises me though, that there are many aftermarket rods for the type 1, yet very few for the 4.

Pd

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Old 11-15-2002, 01:54 PM
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Still surprises me though, that there are many aftermarket rods for the type 1, yet very few for the 4.

That shouldn't surprise anyone. Just look at the relative numbers of units made. Lots more Type I-powered vehicles out there, therefore lots more demand for parts of all kinds.

That's why just about everything Type I is cheaper than just about everything Type IV.

--DD
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Old 11-15-2002, 02:03 PM
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rods

I am getting ready to rebuild my 1.7 914 motor. Are you guys saying that I can put type 1 rods in my 1.7 without any mods? If so, what are the benefits etc..drawbacks??What exactly would I need. Is there a deck height issue? Thanx, Todd
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Old 11-15-2002, 02:45 PM
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Todd,

Your playing with fire. The type 4 rods are fine. If you want to do something get some metal crabide tips for a air grinder and debur your factory rods and have them balanced with the rest of the engine.

I promise there are less than 1% of the type 4 engines out there with Type 1 rods. It is not a bolt on procedure.

I actually see NO benefit.

B
Old 11-15-2002, 02:53 PM
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Well

I see. I was curious why the type 1 motor seems so much more peppy. I have a friend who has a bone stock 68 Vw bus and it's got a ton of low end get up and go. My other friend has a 74 bus 2.0 w/ hydros and mallory dist. and the 68 smokes him every time. Why is there such a power difference? Im sure the 74 would tow more and it has more power, but the 68 just gets right with it. I dont have much experience with the type 1 motor so I dont know the reason why it seems so much faster for a smaller engine.
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Actually,the 914 is a "Poor Man's Porsche". You buy one and you end up poor...Or it ends up covered with Por 15? Either way, something's poor...
Old 11-15-2002, 02:58 PM
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This is a VW guy question:

What year did VW stop using the gear reduction boxes on the buses ? (This may or may not contribute to your buddy's 68 bus being faster than the later bus)

B
Old 11-15-2002, 03:15 PM
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Todd,

you can't use type 1 rods without going to a crankshaft that is ground to the width and diameter of the rods, for one thing. Read over the post above to see all the changes which would have to be made.

PD
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Old 11-15-2002, 03:42 PM
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I kinda look at it this way:

If the type 4 stuff was soooo bad then why do all the top Type1 engine builders like to use Type4 main bearings in their cases ? All the aftermarket Type1 cases also ship with type 4 main bearings. Hummm. Maybe the type 4 isnt so bad.

B
Old 11-15-2002, 03:45 PM
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