3.1 hopup

[Stevesr]

Ok,I haven't chimmed in on this board for almost a year now,it has taken me this long to get my engine installed.
Some of you might remember the guy who was putting the 3.1 in a Porsche 914? Well,I've done it! And I know this has been hashed over and over but here goes anyway(again).I want to use late model 3100 heads and 3400 intakes on my rebuild.I have a 1991 genII from a Corsica.
What year heads and intake should I look for? Also,piston,cam recomendations?

Steve

[v6h.o.]

i'd look for a set of 3400 Heads Intakes and exhaust manifolds.
or the 2000 model year or newer 3100 heads/intakes/exh. they are the same now between the two engines, previous to this the 3400 3100 had different sized ports/ intake valve ect.

what are you looking for in a cam? performance goals.

[Stevesr]

I would like to get about 180hp,this car will be a weekend autoxer and boy racer.
It won't be driven everyday. As for exhaust,keep in mind the 914 is a rear drive mid-engine car so the transverse engine now sits lengthwise.
So custom headers are now in order.

Steve
94 Grandprix
93 F-150 4x4
71 Porsche 914 in pieces

[RacerX11]

Here is what I would recommend.

Mild combo:

3100 pistons (9.6 CR)
3400-style heads/intake (1996+ 3400, or 2000+ 3100)
Mild performance cam (Crane H260 or equivalent)
62mm TB
Headers

This should get you an easy 200 HP. The late 3100?s (2000+) with the 3400 top end stuff were rated 170-175 HP stock. Throw in the above parts (mainly heads) with a good ECM tune, and 200 should be easy. This combo would be very streetable.

For a more aggressive build, add the following:
3.1 Camaro iron-head pistons (~11.? CR)
More aggressive cam (Crane H272 or equivalent, maybe solid cam)
Ported heads and intake

Two of the biggest bottlenecks in the 3100/3400 engine are the roller cam (lack of aftermarket grinds), and the lack of headers. With your 3.1 bottom end with flat tappet cam, your options are plentiful, and you already plan on custom headers. With the more agressvie build, you should be able to get ~220 HP. This combo would still be very streetable, and would make a nice engine for the 914 chassis.

Marty

[Stevesr]

Marty,so you are saying that the 3100/3400 engines have roller cams and the 3.1 have flat tappets but there is no problem with using the 3100/3400 heads on my old style bottom end?
What about pushrods? Will mine work?
Also the 62MM throttle body is a aftermarket piece,is this readly available?
My fuel rail and injectors from the 3.1 will fit?


Steve

[v6h.o.]

Stevesr,

check out our site dedicated to the 3X00 engine "top end" swap and full on 3400 replacement.

http://www.domesticcrew.com/660

[RacerX11]

Yes. The 3100/3400 top end will work fine with the 3.1 bottom end. You will probably need custom length pushrods, depending on what cam and rockers you end up with.

The 62mm TB is a readily available aftermarket piece. The best place to get it is http://www.fdpperformance.com/ however, they are currently moving, so they aren't selling parts again until March 1st. There are several links on their site for other vendors who are carrying the FDP products in the interim.

You will need the entire 3100/3400 top end (heads, lower/upper intake, fuel rail (3.1 fuel rail will not fit), power steering pump. I think there may be more, but you should check out the other info posted at http://www.60degreev6.com/index.php?p=pages&pid=181 regarding the 3100 top end swap. There is lots of info their that I don't want to repeat.

Marty

Edit: I guess Colin beat me to the response

[Stevesr]

Thanks.Colin&Marty for your info,that gives me a good start.
I checked out the domesticcrew.com site,some of it will apply and some won't.
But now Iv'e got a direction to head.So now off to the bone yard!!

Steve

[geoffinbc]

Two of the biggest bottlenecks in the 3100/3400 engine are the roller cam (lack of aftermarket grinds), and the lack of headers. With your 3.1 bottom end with flat tappet cam, your options are plentiful, and you already plan on custom headers. With the more agressvie build, you should be able to get ~220 HP. This combo would still be very streetable, and would make a nice engine for the 914 chassis.

Marty

3100 and 3400 cams can be ditched if you are using it on an MPFI motor. You can then use and aftermarket roller cam ment for the 60* V6. Crane or Comp will make you one.

[RacerX11]

Like I said, with the 3.1 bottom end, options are plentiful. No need to spend the extra money on an aftermarket roller cam when many of the off-the-shelf flat-tappet performce cams will get him the power he is looking for.

Marty

[Stevesr]

I would almost be money ahead if I looked for a complete 3400 engine,then I would have the pistons(providing they were reusable),the upper and lower intakes,the fuel rail and the throttle body that could be swapped out later with the 62MM one.Then the only issue would be the custom push rods???

Steve